Graft modified polyglycolic acid copolymer as well as preparation method and application thereof

Abstract

The invention relates to the field of high polymer materials, and discloses a graft modified polyglycolic acid copolymer as well as a preparation method and application thereof. The preparation method of the graft modified polyglycolic acid copolymer comprises the following steps: grafting and pre-polymerizing a mixed material containing a polyglycolic acid monomer, a grafting monomer, a free radical initiator, a ring-opening polymerization initiator, a ring-opening polymerization catalyst and an optional stabilizing aid, and then polymerizing, wherein the reaction temperature of grafting and prepolymerization is lower than the temperature of polymerization. The obtained copolymer is excellent in performance in all aspects, good in stability, good in toughness, good in compatibility and beneficial to subsequent processing, the prepared graft modified polyglycolic acid copolymer enables the process to be continuous and stable when being used for preparing corresponding products, and the products are basically free of crystal points and mist.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a graft-modified polyglycolic acid copolymer and a preparation method and application thereof. Background Art

[0002] Polyglycolic acid (PGA) is the simplest linear aliphatic polyester. PGA can be prepared through direct polycondensation of glycolic acid, dealcoholization polycondensation of glycolate, desalination polycondensation of glycolate, or ring-opening polymerization of glycolide. Due to its regular molecular structure, PGA is a typical highly crystalline polymer with a stable lattice and a high melting point. Furthermore, its thermal degradation temperature is close to its melting point, making it susceptible to degradation during molding and processing. The processing range is much narrower than that of other biodegradable materials, which has a negative impact on its use and promotion. PGA is easily hydrolyzed, has poor stability, and requires harsh storage and transportation conditions, which increases costs.

[0003] Polyglycolic acid (PGA) has excellent biodegradability. It can be completely absorbed and metabolized by the human circulatory system and can also be degraded in vitro. It is currently used in medical sutures, controlled-release drug delivery vehicles, fracture fixation materials, tissue engineering scaffolds, reinforcement materials, temporary plugging materials for oil and gas development, and downhole tools. Through solution spinning and melt spinning, PGA can be processed into surgical sutures with high tensile strength that can be maintained for a sufficient period of time, making it suitable for suturing deep tissue wounds.

[0004] CN111087581A discloses a method for preparing polyglycolic acid, which involves first melt-mixing glycolide and a catalyst at 82-95°C, then cooling and crushing them, and then adding them together with a stabilizer to a twin-screw extruder to complete polymerization. CN114478932A discloses graft-modified polyglycolic acid and its preparation method, which involves adding polyglycolic acid, a grafting monomer, a free radical initiator, etc. to an extruder, and obtaining graft-modified polyglycolic acid after mixed melt reaction and extrusion. CN107556536A discloses a low-cost, bio-based, fully degradable film of PGA / TPS / PBAT. In the prior art, PGA has poor compatibility with other biodegradable materials, resulting in the need to add a large amount of compatibilizer to the blending system. By graft-modifying PGA, its compatibility with other biodegradable materials can be significantly improved, thereby enhancing product performance. However, the products, especially the films, are prone to defects such as crystal points or fogging. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art PGA, such as the occurrence of crystal points or fog when preparing corresponding products, and to provide a graft-modified polyglycolic acid copolymer and its preparation method and application. The graft-modified polyglycolic acid copolymer prepared by the preparation method has excellent performance in all aspects, good stability, good toughness, good compatibility, and is conducive to subsequent processing.

[0006] To achieve the above objectives, the present invention provides, in a first aspect, a novel method for preparing a grafted modified polyglycolic acid copolymer, wherein the method comprises: grafting and prepolymerizing a mixture containing a polyglycolic acid monomer, a grafting monomer, a free radical initiator, a ring-opening polymerization initiator, a ring-opening polymerization catalyst, and optionally a stabilizing agent, and then polymerizing the mixture; wherein the reaction temperature of the grafting and prepolymerization is lower than the polymerization temperature.

[0007] The second aspect of the present invention provides a graft-modified polyglycolic acid copolymer prepared by the preparation method of the present invention.

[0008] The third aspect of the present invention provides the use of the graft-modified polyglycolic acid copolymer of the present invention in the fields of injection molding, casting and blown film processing.

[0009] The fourth aspect of the present invention provides the use of the graft-modified polyglycolic acid copolymer of the present invention in blown films, cast films, multilayer films, sheets, fibers and injection molded products.

[0010] Compared with the prior art, the present invention has at least the following beneficial effects:

[0011] Polyglycolic acid resins have a small temperature difference between their decomposition and melting temperatures, making them susceptible to thermal degradation during melt processing. This results in poor toughness and poor compatibility with other polymers, such as the biodegradable material PBAT, leading to poor performance. The polyglycolic acid graft copolymer resins of the present invention, however, incorporate grafting monomers for copolymerization during the synthesis phase, avoiding waste and degradation during secondary processing. Grafting and prepolymerization are performed prior to polymerization, resulting in a continuous and stable preparation process. The resulting copolymers exhibit excellent properties across the board, including stability, toughness, and compatibility, facilitating subsequent processing. They are suitable for use as polymer materials, such as sheets, films, fibers, blow-molded products, composite materials, and other molded products. DETAILED DESCRIPTION

[0012] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0013] As mentioned above, existing PGA may have defects such as crystal points or fog when preparing corresponding products. After extensive research, the present invention proposes a new method for preparing a grafted modified polyglycolic acid copolymer, wherein the preparation method comprises: grafting and prepolymerizing a mixture containing polyglycolic acid monomer, grafting monomer, free radical initiator, ring-opening polymerization initiator, ring-opening polymerization catalyst and optionally a stabilizing agent, and then polymerizing; wherein the reaction temperature of the grafting and prepolymerization is lower than the polymerization temperature.

[0014] The preparation method of the present invention avoids consumption and degradation in secondary processing. Grafting and prepolymerization are first performed, and then polymerization is performed. The preparation process is continuous and stable. The obtained copolymer has excellent performance in all aspects, good stability, good toughness, and good compatibility, and is conducive to subsequent processing. The prepared grafted modified polyglycolic acid copolymer is used to prepare corresponding products, so the process is continuous and stable, and the products are basically free of crystal points and fog.

[0015] In the present invention, grafting and prepolymerization refer to the simultaneous occurrence of a grafting reaction during prepolymerization. In some embodiments, the grafting and prepolymerization conditions include a reaction temperature of 80-160°C, for example, 80°C, 85°C, 90°C, 100°C, 120°C, 150°C, 160°C, or a range consisting of any two of the above values. The grafted modified polyglycolic acid copolymer prepared using the aforementioned embodiment has good stability, toughness, and compatibility, facilitating subsequent processing. When used to prepare corresponding products, the process is continuous and stable, and the products are substantially free of crystal points and fog.

[0016] According to the present invention, in some embodiments, the grafting and prepolymerization conditions include a reaction time of 0.5-5 hours, for example, 0.5 hours, 1 hour, 3 hours, 5 hours, or a range consisting of any two of the above values. The graft-modified polyglycolic acid copolymer prepared using the aforementioned embodiment has good stability, toughness, and compatibility, is convenient for subsequent processing, and is used to prepare corresponding products in a continuous and stable process. The products are substantially free of crystal points and fog.

[0017] According to the present invention, in some embodiments, the polymerization conditions include: a reaction temperature of 160-250°C, for example, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, or a range consisting of any two of the above values, preferably 200-240°C. The graft-modified polyglycolic acid copolymer prepared using the above embodiment has good stability, good toughness, and good compatibility, which is conducive to subsequent processing. When used to prepare corresponding products, the process is continuous and stable, and the products are substantially free of crystal points and fog.

[0018] According to the present invention, in some embodiments, the polymerization conditions include a reaction time of 0.5-60 min, for example, 0.5 min, 1 min, 2 min, 2.5 min, 3 min, 5 min, 8 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or a range consisting of any two of the above values, preferably 1-10 min. The graft-modified polyglycolic acid copolymer prepared using the above embodiment has good stability, good toughness, and good compatibility, is convenient for subsequent processing, and is used to prepare corresponding products, ensuring a continuous and stable process, and the products are substantially free of crystal points and fog.

[0019] According to the present invention, the viscosity of the system in the prepolymerization stage is low and the stirring requirement is not high. Under the premise of achieving the purpose of the present invention, the grafting and prepolymerization can be carried out in a reactor with heating and stirring mixing functions, such as a conventional reactor in the art.

[0020] According to the present invention, the viscosity of the system increases rapidly during the polymerization stage, and strong stirring and mixing capabilities are required. Under the premise of achieving the purpose of the present invention, the polymerization is carried out in a device with heating and strong stirring and mixing capabilities. Specifically, the devices that can be listed include a series combination of one or more of a kettle reactor, a tubular reactor, an internal mixer, a Farrel continuous mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder and a reciprocating single-screw extruder, preferably a multi-screw extruder (e.g., a twin-screw extruder).

[0021] In the present invention, a pipeline with a heat preservation function can be used to connect the reactor for grafting and prepolymerization and the reaction device for polymerization. Usually, the pipeline temperature is the same as the reaction temperature for grafting and prepolymerization. The prepolymer obtained by grafting and prepolymerization can be transferred to the device for polymerization by gravity or inert gas pressure.

[0022] In the embodiments of the present invention, a Labtech parallel co-rotating twin-screw extruder is used as the polymerization apparatus to further illustrate the advantages of the present invention, but the present invention is not limited thereto. During polymerization, the flow rate of the material melt entering the twin-screw extruder can be selected as needed, for example, 1-5 kg / hr; the screw speed can also be selected as needed, for example, 50-200 rpm. In addition, when polymerization is carried out using the Labtech parallel co-rotating twin-screw extruder, the polymerization reaction time is the residence time of the material in the Labtech parallel co-rotating twin-screw extruder.

[0023] In the present invention, after the polymerization is completed, the polymerized material can be made into a desired shape as needed. For example, after the polymerization, cylindrical particles can be obtained by extrusion, cooling, and pelletizing.

[0024] In the present invention, the optional stabilizing agent means that it can be added or not added as needed. As long as the purpose of the present invention can be achieved, the amount of each component in the mixture is not particularly limited. In some preferred embodiments, the mixture contains, by mass: 1000 parts of polyglycolic acid monomer, 10-200 parts of grafting monomer (for example, 10 parts, 20 parts, 30 parts, 50 parts, 70 parts, 100 parts, or a range consisting of any two of the above values), 0.1-10 parts of free radical initiator (for example, 0.1 part, 1 part, 2.5 parts, 5 parts, 10 parts, or a range consisting of any two of the above values), a ring-opening polymerization initiator 0.05-5 parts (for example, 0.05 parts, 0.5 parts, 1 parts, 3 parts, 5 parts, or a range consisting of any two of the above values), a ring-opening polymerization catalyst 0.01-5 parts (0.01 parts, 0.1 parts, 0.2 parts, 1 parts, 3 parts, 5 parts, or a range consisting of any two of the above values), and a stabilizing agent 0-50 parts (for example, 0 parts, 1 parts, 3 parts, 8 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, or a range consisting of any two of the above values). By adopting the above embodiment, the consumption and degradation of PGA secondary processing can be avoided, and the obtained copolymer has excellent performance in all aspects, good stability, good toughness, good compatibility, is conducive to subsequent processing, and is used to prepare corresponding products so that the process is continuous and stable, and the products are basically free of crystal points and fog.

[0025] According to the present invention, in some embodiments, the grafted monomer has at least one α-, β-unsaturated group. This embodiment avoids consumption and degradation of PGA during secondary processing, and the resulting copolymer exhibits excellent properties in various aspects, including stability, toughness, and compatibility, facilitating subsequent processing. The copolymer is used to prepare corresponding products, ensuring a continuous and stable process, and the products are essentially free of crystallinity and fog.

[0026] According to the present invention, in some preferred embodiments, the α- and β-unsaturated groups include at least one of vinyl groups, acrylate groups, methacrylate groups, allyl groups, and acetylene groups. Examples of grafting monomers include n-butyl methacrylate and dibutyl maleate, with n-butyl methacrylate being preferred. Using these embodiments, consumption and degradation of PGA during secondary processing can be effectively avoided. The resulting copolymers exhibit excellent properties in various aspects, including stability, toughness, and compatibility, facilitating subsequent processing. The process for preparing corresponding products is continuous and stable, and the products are substantially free of crystallinity and fog.

[0027] According to the present invention, polyglycolic acid monomers refer to polyglycolic acid segments obtained by polymerization. In some embodiments, the polyglycolic acid monomer is selected from at least one of methyl glycolate, glycolic acid and glycolide, preferably glycolide.

[0028] According to the present invention, in some embodiments, the ring-opening polymerization initiator is selected from a small molecule substance containing a hydroxyl group or an amino group and having a molecular weight of less than 1000 g / mol, with a boiling point greater than 160°C. The copolymer prepared using the aforementioned embodiment exhibits excellent properties in various aspects, including good stability, toughness, and compatibility, facilitating subsequent processing. The process for preparing the corresponding products is continuous and stable, and the products are substantially free of crystallinity and fog.

[0029] According to the present invention, in some preferred embodiments, the ring-opening polymerization initiator includes at least one of ethylene glycol, butanediol, glycerol, serinol, leucinol, pentaerythritol, sorbitol, xylitol, amino acids, phenol, hydroquinone, resorcinol, benzyl alcohol, aniline, benzylamine, p-phenylenediamine, m-phenylenediamine, hexamethylenediamine and dodecanediamine. In the embodiments of the present invention, butanediol, specifically 1,4-butanediol, is used as the ring-opening polymerization initiator to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0030] According to the present invention, in some embodiments, the ring-opening polymerization catalyst is selected from salt compounds corresponding to at least one of Group IIA metal elements, Group IIA metal elements, Group III metal elements, Group IVA metal elements, Group VA metal elements, and transition metal elements, or an organic guanidine catalyst. The copolymers prepared using the aforementioned embodiments exhibit excellent properties in various aspects, including good stability, toughness, and compatibility, facilitating subsequent processing. When used to prepare corresponding products, the process is continuous and stable, and the products are substantially free of crystallinity and fog.

[0031] According to the present invention, in some preferred embodiments, the catalyst is a salt compound corresponding to at least one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti, and Zn, preferably a Sn salt. The copolymer prepared using the aforementioned embodiment has excellent performance in all aspects, including good stability, good toughness, and good compatibility, and is easy to process subsequently. When used to prepare corresponding products, the process is continuous and stable, and the products are substantially free of crystal points and fog.

[0032] According to the present invention, the free radical initiator used is an organic compound that can decompose to produce free radicals under certain conditions, including but not limited to: at least one of acyl peroxides, alkyl (dialkyl) peroxides, aromatic hydrocarbon-substituted alkyl (aromatic hydrocarbon-substituted dialkyl) peroxides, peresters, alkyl hydroperoxides, ketone peroxides and azo compounds; for example, acyl peroxides, dibenzoyl peroxide, dioctanoyl peroxide, di(tert-butyl), di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, butyl peracetate, di-tert-butyl perglutarate, di-tert-butyl perphthalate, tert-butyl peroxyketal, tert-amyl peroxyketal, azobisisobutyronitrile, etc.

[0033] According to the present invention, the stabilizing aid includes a thermal stabilizer, including but not limited to at least one of phosphonates, phosphites and sulfur-containing compounds, preferably at least one of antioxidant 1010, antioxidant 1024, antioxidant 1076, antioxidant 168, antioxidant 608 and antioxidant 626.

[0034] According to the present invention, the stabilizing agent includes an anti-hydrolysis agent, including but not limited to carbodiimide compounds.

[0035] The second aspect of the present invention provides a graft-modified polyglycolic acid copolymer prepared by the preparation method of the present invention.

[0036] In the present invention, the grafted modified polyglycolic acid copolymer prepared by the preparation method of the present invention has good stability, good toughness, and good compatibility compared to the existing PGA, is conducive to subsequent processing, and is suitable for use as polymer materials such as sheets, films, fibers, blow-molded products, composite materials, and other molded products.

[0037] The graft-modified polyglycolic acid copolymer of the present invention has no particular application limitation, and has a wide range of applications, for example but not limited to, in medicine, daily necessities, packaging, and the like.

[0038] According to the present invention, in some embodiments, the weight average molecular weight of the grafted modified polyglycolic acid copolymer is 150,000-500,000 g / mol, for example, 150,000 g / mol, 160,000 g / mol, 170,000 g / mol, 180,000 g / mol, 190,000 g / mol, 220,000 g / mol, 270,000 g / mol, 300,000 g / mol, 400,000 g / mol, 550,000 g / mol, or a range consisting of any two of the above values.

[0039] According to the present invention, in some embodiments, the molecular weight distribution index of the graft modified polyglycolic acid copolymer is 1.1-2.5, for example, 1.1, 1.4, 1.5, 1.6, 1.8, 2.0, 2.3, 2.5, or a range consisting of any two of the above values.

[0040] According to the present invention, in some embodiments, the grafted modified polyglycolic acid copolymer has a melt index of 8-20 g / 10 min at 230° C. and 2.16 kg, for example, 8 g / 10 min, 13 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, 20 g / 10 min, or a range consisting of any two of the above values.

[0041] The third aspect of the present invention provides the use of the graft-modified polyglycolic acid copolymer of the present invention in the fields of injection molding, casting and blown film processing.

[0042] In the present invention, the graft-modified polyglycolic acid copolymer of the present invention has good stability, good toughness, and good compatibility, and is conducive to the processing methods of injection molding, casting and film blowing.

[0043] The fourth aspect of the present invention provides the use of the graft modified polyglycolic acid copolymer of the present invention in blown films, cast films, multilayer films, sheets, fibers and injection molded products.

[0044] In the present invention, the product prepared by using the graft-modified polyglycolic acid copolymer of the present invention is substantially free of crystal points and fog.

[0045] The present invention will be described in detail below by way of examples. In the following examples:

[0046] Glycolide (GA) was purchased from Shenzhen Boli Biomaterial Co., Ltd. with a purity of ≥99.5%;

[0047] Butyl methacrylate, dibutyl maleate, Chinese medicine reagent grade;

[0048] Benzoyl peroxide (BPO), azobisisobutyronitrile (AIBN), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, Chinese medicine reagent grade;

[0049] Stannous octoate (AR grade) and 1,4-butanediol (CP grade) were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0050] Antioxidant 1010 was purchased from BASF (China) Co., Ltd., and antioxidant 626 (THP-24) was purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with a purity of ≥95%.

[0051] The performance was measured as follows:

[0052] Gel permeation chromatography (GPC): The test was performed on a PL-GPC50 gel permeation chromatograph produced by Angilent, USA. The processing software was GPC offline. During the test, the mobile phase was hexafluoroisopropanol containing 5 mmol / L sodium trifluoroacetate, the flow rate was 1 mL / min, the column temperature was 40°C, the injection volume was 100 μL, the standard sample was PMMA, and the sample concentration was 1 mg / mL.

[0053] Melt Flow Index (MFR): measured in accordance with ISO 1133 using a Lloyd DAVENPORT™ MFI-10 / 230 melt indexer with a barrel temperature of 230°C, a load of 2.16 kg, a die diameter of 2.095 mm, a length of 8 mm, and a preheating time of 240 seconds. Samples were automatically cut at set intervals and the average of five samples was calculated. Results are expressed in grams per 10 minutes (g / 10 min).

[0054] Example 1

[0055] Glycol (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and azobisisobutyronitrile were added to a reactor with heating and stirring functions in a mass ratio of 1000:3:5:0.2:0.5:20:1. The set temperature of the reactor was 85°C. The materials were heated, stirred, mixed, and reacted in the reactor for 60 minutes. After that, the material melt was transferred to a Labtech parallel co-rotating twin-screw extruder through a conduit set at 85°C with the assistance of compressed nitrogen. By adjusting the compressed nitrogen The air flow rate was controlled to control the flow rate of the material melt entering the twin-screw extruder at about 2 kg / hr. The Labtech parallel co-rotating twin-screw extruder temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the spline was extruded from the die and air-cooled, it was cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer. These were grafted modified polyglycolic acid copolymers.

[0056] According to the method described above, the melt index was determined to be 18.2 g / 10 min, the weight average molecular weight was 163,000 g / mol, and the molecular weight distribution was 1.4.

[0057] Example 2

[0058] The method of Example 1 was followed, except that the material ratio was adjusted to: the mass ratio of glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and azobisisobutyronitrile was 1000:3:5:0.2:0.5:50:2.5, and a graft-modified polyglycolic acid copolymer was finally prepared.

[0059] According to the method described above, the melt index was determined to be 16.8 g / 10 min, the weight average molecular weight was 174,000 g / mol, and the molecular weight distribution was 1.5.

[0060] Example 3

[0061] The method of Example 1 was followed, except that the material ratio was adjusted to: the mass ratio of glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and azobisisobutyronitrile was 1000:3:5:0.2:0.5:100:5, and a graft-modified polyglycolic acid copolymer was finally prepared.

[0062] According to the method described above, the melt index was determined to be 15.8 g / 10 min, the weight average molecular weight was 191,000 g / mol, and the molecular weight distribution was 1.8.

[0063] Example 4

[0064] Glycol (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, dibutyl maleate, and dibenzoyl peroxide were added to a reactor with heating and stirring functions in a mass ratio of 1000:3:5:0.2:0.5:20:1. The set temperature of the reactor was 100°C. The materials were heated, stirred, mixed, and reacted in the reactor for 60 minutes. After that, the material melt was transferred to a Labtech parallel co-rotating twin-screw extruder through a conduit set at 100°C with the assistance of compressed nitrogen. By adjusting the compressed nitrogen The air flow rate was used to control the flow rate of the material melt entering the twin-screw extruder at about 2 kg / hr. The Labtech parallel co-rotating twin-screw extruder temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the splines were extruded from the die and air-cooled, they were cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer. They were grafted modified polyglycolic acid copolymers.

[0065] According to the method described above, the melt index was determined to be 17.8 g / 10 min, the weight average molecular weight was 171,000 g / mol, and the molecular weight distribution was 1.8.

[0066] Example 5

[0067] The method of Example 4 was followed, except that the material ratios were adjusted: the mass ratios of glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, dibutyl maleate, and dibenzoyl peroxide were 1000:3:5:0.2:0.5:50:2.5, and a graft-modified polyglycolic acid copolymer was finally prepared.

[0068] The melt index, weight average molecular weight, and molecular weight distribution were 16.5 g / 10 min, 178,000 g / mol, and 2.0, respectively.

[0069] Example 6

[0070] Glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane were added to a reactor with heating and stirring functions in a mass ratio of 1000:3:5:0.2:0.5:20:1. The set temperature of the reactor was 100°C. The materials were heated, stirred, mixed, and reacted in the reactor for 60 minutes. After that, the material melt was transferred to a Labtech parallel co-rotating twin-screw extruder through a conduit set at 100°C with the assistance of compressed nitrogen. The flow rate of the compressed nitrogen was controlled to be approximately 2 kg / hr. The Labtech parallel co-rotating twin-screw extrusion temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was approximately 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the splines were extruded from the die and air-cooled, they were cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer. These were grafted modified polyglycolic acid copolymers.

[0071] According to the method described above, the melt index was determined to be 17.2 g / 10 min, the weight average molecular weight was 176,000 g / mol, and the molecular weight distribution was 1.6.

[0072] Example 7

[0073] The method of Example 6 was followed, except that the material ratios were adjusted: the mass ratios of glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane were 1000:3:5:0.2:0.5:50:2.5, and a graft-modified polyglycolic acid copolymer was finally prepared.

[0074] The melt index, weight average molecular weight, and molecular weight distribution were 15.9 g / 10 min, 191,000 g / mol, and 2.0, respectively.

[0075] Example 8

[0076] The method of Example 6 was followed, except that the material ratios were adjusted: the mass ratios of glycolide (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, 1,4-butanediol, n-butyl methacrylate, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane were 1000:3:5:0.2:0.5:100:5, and a graft-modified polyglycolic acid copolymer was finally prepared.

[0077] According to the method described above, the melt index was determined to be 13.5 g / 10 min, the weight average molecular weight was 221,000 g / mol, and the molecular weight distribution was 1.5.

[0078] Comparative Example 1

[0079] Glycol (GA), antioxidant 1010, antioxidant THP-24, stannous octoate, and 1,4-butanediol were added to a reactor with heating and stirring functions in a mass ratio of 1000:3:5:0.2:0.5. The set temperature of the reactor was 100°C. The materials were heated, stirred, mixed, and reacted in the reactor for 60 minutes. After that, the material melt was transferred to a Labtech parallel co-rotating twin-screw extruder through a conduit set at 100°C with the assistance of compressed nitrogen. The flow rate of the compressed nitrogen was controlled to be approximately 2 kg / hr. The Labtech parallel co-rotating twin-screw extrusion temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the spline was extruded from the die and air-cooled, it was cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer, which were PGA particles.

[0080] According to the method described above, the melt index was determined to be 20.9 g / 10 min, the weight average molecular weight was 152,000 g / mol, and the molecular weight distribution was 1.7.

[0081] Comparative Example 2

[0082] The PGA particles prepared in Comparative Example 1 were thoroughly mixed with n-butyl methacrylate and azobisisobutyronitrile in a mass ratio of 1000:50:2.5, and then added to a Labtech parallel co-rotating twin-screw extruder at a rate of 2 kg / hr. The extruder temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the spline was extruded from the die and air-cooled, it was cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer, which were grafted modified polyglycolic acid copolymers.

[0083] According to the method described above, the melt index was determined to be 25.8 g / 10 min, the weight average molecular weight was 128,000 g / mol, and the molecular weight distribution was 1.8.

[0084] Comparative Example 3

[0085] The PGA particles prepared in Comparative Example 1 were thoroughly mixed with dibutyl maleate and dibenzoyl peroxide in a mass ratio of 1000:50:2.5, and then added to a Labtech parallel co-rotating twin-screw extruder at a rate of 2 kg / hr. The extruder temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the spline was extruded from the die and air-cooled, it was cut into cylindrical light yellow particles with a length of about 3 mm by a pelletizer, which were grafted modified polyglycolic acid copolymers.

[0086] According to the method described above, the melt index was determined to be 24.6 g / 10 min, the weight average molecular weight was 134,000 g / mol, and the molecular weight distribution was 1.8.

[0087] Comparative Example 4

[0088] The PGA particles prepared in Comparative Example 1 were thoroughly mixed with n-butyl methacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in a mass ratio of 1000:20:1, and then added to a Labtech parallel co-rotating twin-screw extruder at a rate of 2 kg / hr. The extruder temperatures were set to 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 220°C, 220°C, and 220°C, respectively. The screw speed was set to 100 rpm, and the residence time was about 2.5 min. The extruder was equipped with a circular die with a diameter of 3 mm. After the spline was extruded from the die and air-cooled, it was cut into cylindrical light yellow particles with a length of about 3 mm using a pelletizer, which were grafted modified polyglycolic acid copolymers.

[0089] According to the method described above, the melt index was determined to be 22.7 g / 10 min, the weight average molecular weight was 145,000 g / mol, and the molecular weight distribution was 1.6.

[0090] Application Examples

[0091] The graft-modified polyglycolic acid copolymers prepared in Examples 1-8 and Comparative Examples 2-4 were used to produce cast films (process performance is shown in Table 1) on a HAAKE™ Rheomex OS single-screw extruder manufactured by ThermoFisher Scientific Inc., USA. The extruder had a screw diameter of 19 mm, an aspect ratio of 25, and a standard 3:1 metering screw. The extruder was controlled by a HAAKE™ PolyLab™ OS torque rheometer platform. The extruder had three heating sections, numbered 1-3 from the feed inlet to the outlet, and was equipped with a casting die with a width of 150 mm and an opening height of 0.6 mm. The extruder and die temperatures were set at 200°C, 230°C, 230°C, and 230°C, respectively. Films were subsequently drawn and stretched using three 30°C guide rollers. The cast film thickness was controlled to approximately 80 μm by adjusting the extruder screw and guide roller speeds.

[0092] The present invention uses crystal points and mist appearing during film making to characterize product performance. If the number of crystal points in the film is small and the particles are small, it indicates that the grafted product has better performance. The less mist, the better the performance of the grafted product.

[0093] Table 1

[0094]

[0095]

[0096] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a graft-modified polyglycolic acid copolymer, wherein: The preparation method comprises: grafting and prepolymerizing a mixture containing polyglycolic acid monomer, grafting monomer, free radical initiator, ring-opening polymerization initiator, ring-opening polymerization catalyst and optionally a stabilizing auxiliary agent, and then polymerizing; Wherein, the reaction temperature of the grafting and prepolymerization is lower than the polymerization temperature.

2. The preparation method according to claim 1, wherein The grafting and prepolymerization conditions include: a reaction temperature of 80-160° C., and / or a reaction time of 0.5-5 hours; and / or The polymerization conditions include: a reaction temperature of 160-250° C., preferably 200-240° C., and / or a reaction time of 0.5-60 min, preferably 1-10 min; and / or The grafting and prepolymerization are carried out in a reactor with heating and stirring mixing functions; and / or The polymerization is carried out in a device with heating and strong stirring and mixing capabilities. Preferably, the device for carrying out the polymerization includes a series combination of one or more of a kettle reactor, a tubular reactor, an internal mixer, a Farrel continuous mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder and a reciprocating single-screw extruder, and more preferably a multi-screw extruder.

3. The preparation method according to claim 1 or 2, wherein The mixture contains, by mass, 1000 parts of polyglycolic acid monomer, 10-200 parts of grafting monomer, 0.1-10 parts of free radical initiator, 0.05-5 parts of ring-opening polymerization initiator, 0.01-5 parts of ring-opening polymerization catalyst, and 0-50 parts of stabilizing agent.

4. The preparation method according to any one of claims 1 to 3, wherein The grafting monomer has at least one α, β-unsaturated group; Preferably, the α, β-unsaturated group includes at least one of a vinyl group, an acrylate group, a methacrylate group, an allyl group and an acetylene group; and / or The polyglycolic acid monomer is selected from at least one of methyl glycolate, glycolic acid and glycolide, preferably glycolide.

5. The preparation method according to any one of claims 1 to 4, wherein The ring-opening polymerization initiator is selected from small molecules containing hydroxyl or amino groups with a boiling point greater than 160° C. and a molecular weight less than 1000 g / mol, preferably including at least one of ethylene glycol, butanediol, glycerol, serinol, leucinol, pentaerythritol, sorbitol, xylitol, amino acids, phenol, hydroquinone, resorcinol, benzyl alcohol, aniline, benzylamine, p-phenylenediamine, m-phenylenediamine, hexamethylenediamine and dodecanediamine; and / or The ring-opening polymerization catalyst is selected from salt compounds corresponding to at least one of Group IIA metal elements, Group IIA metal elements, Group III metal elements, Group IVA metal elements, Group VA metal elements and transition metal elements, or organic guanidine catalysts. Preferably, the catalyst is a salt compound corresponding to at least one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti and Zn, and is more preferably a Sn salt.

6. The preparation method according to any one of claims 1 to 5, wherein The free radical initiator is selected from at least one of acyl peroxides, alkyl (dialkyl) peroxides, aromatic hydrocarbon-substituted alkyl (aromatic hydrocarbon-substituted dialkyl) peroxides, peresters, alkyl hydroperoxides, ketone peroxides and azo compounds.

7. The preparation method according to any one of claims 1 to 6, wherein The stabilizing aid includes a heat stabilizer and / or an anti-hydrolysis agent; Preferably, the heat stabilizer comprises at least one of phosphonates, phosphites and sulfur-containing compounds, preferably at least one of antioxidant 1010, antioxidant 1024, antioxidant 1076, antioxidant 168, antioxidant 608 and antioxidant 626; and / or The anti-hydrolysis agent is selected from carbodiimide compounds.

8. A graft-modified polyglycolic acid copolymer prepared by the preparation method according to any one of claims 1 to 7; Preferably, the weight average molecular weight of the graft-modified polyglycolic acid copolymer is 150,000-500,000 g / mol; and / or The molecular weight distribution index of the graft modified polyglycolic acid copolymer is 1.1-2.5; and / or The graft modified polyglycolic acid copolymer has a melt index of 8-20 g / 10 min at 230° C. and 2.16 kg.

9. Use of the graft modified polyglycolic acid copolymer according to claim 8 in the fields of injection molding, casting and blown film processing.

10. Use of the graft modified polyglycolic acid copolymer according to claim 8 in blown films, cast films, multilayer films, sheets, fibers and injection molded products.

Images