Polyglycolic acid foaming material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a polyglycolic acid foaming material as well as a preparation method and application thereof, and the polyglycolic acid foaming material is prepared by foaming a foaming composition containing a homogeneous continuous phase polyglycolic acid material with multimodal molecular weight distribution. Compared with an unfoamed polyglycolic acid material, the density of the obtained polyglycolic acid foaming material is remarkably reduced, the yield of products with the same quality is increased, the heat insulation property of the obtained products is improved, the use scene of PGA is widened, and more possible use markets are provided.

Description

Technical Field

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

[0002] Polyglycolic acid (PGA), also known as polyglycolic acid or polyglycolide, is a polymer material with excellent biocompatibility and unique biodegradability. Its high crystallinity gives it high strength, making it suitable for applications requiring high strength, such as surgical drug delivery, orthopedic fixation, and tissue repair. However, its high crystallinity also results in a high density, limiting its expanded use cases.

[0003] Methods for reducing material density include foaming modification of the material, adding low-density materials for blending, etc. Among them, there are foam materials prepared for low-density modification of PGA, including a preparation method using supercritical carbon dioxide for twin-screw extrusion. However, this method has problems such as expensive equipment and harsh production conditions, and its industrial application is relatively complicated.

[0004] In contrast, chemical foaming in a twin-screw extruder offers lower equipment requirements, higher effectiveness, and lower costs. However, it places higher demands on the foaming material itself, requiring sufficient melt strength to maintain pores. However, existing PGAs are linear in structure and have a low molecular weight, resulting in insufficient melt strength. These materials typically require chemical modification with chain extenders such as isocyanates and epoxides, or they may need to be combined with other materials to meet foaming requirements.

[0005] CN114045015 (Jiangsu Sailbon Petrochemical Co., Ltd., December 22, 2021) discloses a fully biodegradable foaming net and its preparation method. The foaming material is a blend, of which PGA accounts for only 30% at most, which will affect the mechanical properties and degradation properties of the product. In addition, PGA itself is a material with slow thermal conductivity. Pure PGA is expected to become a good thermal insulation material after foaming. Therefore, the thermal insulation performance of the foamed material after blending will be significantly reduced.

[0006] CN107541031 (Shanghai Pujing Chemical Technology Co., Ltd., June 29, 2016) and CN 115819740 (Shanghai Pujing Chemical Technology Co., Ltd., December 28, 2022) disclose methods for preparing PGA foam materials, but both methods require the additional addition of isocyanates or cross-linking agents for further chemical modification. Isocyanates are toxic and can cause certain harm to the human body and the environment during product preparation and use. The use of cross-linking agents may not only affect the degradation properties of PGA, but also, since chemical modification requires an additional thermal process, it is easy for PGA to be further oxidized and thermally decomposed during the modification process, thereby affecting the quality of the final product.

[0007] The density of the existing polyglycolic acid (PGA) is relatively high and difficult to reduce. In addition, the melt strength of the existing PGA is insufficient and cannot be directly used for the preparation of foaming materials through traditional foaming technology. Therefore, it is necessary to develop a low-density PGA foam material and a simple preparation method thereof to solve the corresponding technical problems. Summary of the Invention

[0008] The inventors have discovered that the polyglycolic acid materials in the prior art have a high density, are difficult to reduce in density, and cannot directly meet foaming requirements without chemical modification. The inventors of the present invention have discovered that a foaming composition comprising a homogeneous continuous phase polyglycolic acid material with a multimodal molecular weight distribution can be directly used to prepare a polyglycolic acid foam material. The resulting polyglycolic acid foam material has a lower density than the polyglycolic acid raw material, resulting in a higher yield of products of the same quality and better thermal insulation properties. It can be used in surgical drug carriers, orthopedic fixation, tissue repair, foamed disposable products, and thermal insulation materials.

[0009] In order to achieve the above objectives, the present invention provides a polyglycolic acid foam material in a first aspect. The polyglycolic acid foam material is prepared by foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution.

[0010] A second aspect of the present invention provides a method for preparing the polyglycolic acid foam material, comprising: extruding and foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution in the presence of a foaming agent.

[0011] The third aspect of the present invention provides a use of the polyglycolic acid foam material in surgical drug carriers, orthopedic fixation, tissue repair, foamed disposable products and thermal insulation materials.

[0012] Through the above technical solution, the present invention provides the above polyglycolic acid foam material and its preparation method and application, which can achieve at least the following beneficial effects:

[0013] (1) The polyglycolic acid foam material provided by the present invention is prepared by using a foaming composition containing a homogeneous continuous phase polyglycolic acid material with a multimodal molecular weight distribution. On the one hand, it can avoid the common industry practice of chemically modifying the conventional polyglycolic acid raw material before it can meet the foaming requirements, and does not require the addition of chain extenders such as isocyanates that may have an impact on the environment; on the other hand, it can avoid the common industry practice of melt blending and heating, and the preparation process requires less heat treatment, which can avoid the oxidation and thermal degradation problems caused by repeated heat treatment of PGA; more importantly, the polyglycolic acid foam material has lower heat resistance and better thermal insulation properties;

[0014] (2) The preparation of polyglycolic acid foam material can be directly carried out by extrusion foaming, which has low equipment requirements, low cost, and is simpler and easier to implement;

[0015] (3) Compared with the unfoamed polyglycolic acid material, the density of the obtained polyglycolic acid foamed material is significantly reduced, which not only increases the yield of products of the same quality, but also improves the thermal insulation of the obtained products, broadens the application scenarios of PGA, and provides more possible application markets. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of a cross section of the polyglycolic acid foam material in Example 1, with a magnification of 200 times;

[0017] Figure 2 This is a scanning electron microscope image of a cross section of the polyglycolic acid foam material in Example 2, with a magnification of 200 times;

[0018] Figure 3 This is a scanning electron microscope image of a cross section of the polyglycolic acid foam material in Example 3, with a magnification of 200 times;

[0019] Figure 4 This is a scanning electron microscope image of a cross section of the polyglycolic acid foam material in Comparative Example 2, with a magnification of 200 times;

[0020] Figure 5 This is a scanning electron microscope image of the surface of the polyglycolic acid foam material in Example 1, with a magnification of 500 times;

[0021] Figure 6 This is a surface scanning electron microscope image of the polyglycolic acid foam material in Comparative Example 2, with a magnification of 500 times. DETAILED DESCRIPTION

[0022] 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.

[0023] A first aspect of the present invention provides a polyglycolic acid foam material. The polyglycolic acid foam material is prepared by foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution.

[0024] The polyglycolic acid foam material provided by the present invention is prepared by foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution. On the one hand, it can eliminate the common industry requirement of chemically modifying conventional polyglycolic acid raw materials before meeting foaming requirements, and does not require the addition of chain extenders such as isocyanates that may have environmental impacts. On the other hand, it can avoid the common industry preparation processes of melt blending and heating, and the preparation process involves one less thermal processing, which can avoid the oxidation and thermal degradation problems caused by repeated thermal processing of PGA. More importantly, the polyglycolic acid foam material has a lower density and also has better thermal insulation properties.

[0025] Foaming composition

[0026] In the present invention, the foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution may further comprise conventional additives in the art as needed. Specifically, these conventional additives include, but are not limited to, at least one of an antioxidant, a foaming promoter, a foaming inhibitor, an anti-hydrolysis agent, an ester exchange inhibitor, and a dispersant. Relative to 100 parts by mass of the polyglycolic acid material: the antioxidant is preferably used in an amount of 0 to 2 parts by mass (preferably 0.5 to 1 part by mass), the foaming promoter is preferably used in an amount of 0 to 100 parts by mass (preferably 10 to 50 parts by mass), the foaming inhibitor is preferably used in an amount of 0 to 30 parts by mass (preferably 1 to 10 parts by mass), the anti-hydrolysis agent is preferably used in an amount of 0 to 2 parts by mass (preferably 0.3 to 1 part by mass), the ester exchange inhibitor is preferably used in an amount of 0 to 2 parts by mass (preferably 0.3 to 1 part by mass), and the dispersant is preferably used in an amount of 0 to 2 parts by mass (preferably 0.3 to 1 part by mass).

[0027] In the present invention, the antioxidant may be a conventional antioxidant in the art, including but not limited to hindered phenol antioxidants and / or phosphite antioxidants. Specific examples of antioxidants include antioxidant BHT, antioxidant TMBTB, antioxidant 2246, antioxidant 259, antioxidant 1010, antioxidant 1024, antioxidant 1098, antioxidant 1076, antioxidant 330, antioxidant TPP, antioxidant TBNPA, antioxidant DPIOP, antioxidant DPPA, antioxidant 1600, antioxidant BDIPP, antioxidant 1608, antioxidant 1600, antioxidant 168, antioxidant 686, antioxidant 626, and the like.

[0028] In the present invention, the foaming promoter refers to a substance that can reduce the decomposition temperature of the foaming agent, including but not limited to at least one of manganese oxide, barium stearate, calcium stearate, calcium hydroxide, diethylene glycol and dibutyltin dimaleate.

[0029] In the present invention, the foaming inhibitor refers to a substance that can deactivate the foaming agent and prolong the time of foaming onset, including but not limited to at least one of maleic acid, fumaric acid, stearyl chloride, phthaloyl chloride, maleic anhydride, phthalic anhydride, hydroquinone, naphthalene diol, glycerol, aliphatic amine, amide, oxime, mercaptan, thiophenol, thiourea, sulfide, phosphate, phosphite and cyclohexanone.

[0030] In the present invention, the anti-hydrolysis agent may be a conventional anti-hydrolysis agent in the art, including but not limited to at least one of monomeric carbodiimide, polymeric carbodiimide, and oxazoline compounds, preferably polymeric carbodiimide.

[0031] In the present invention, the transesterification inhibitor may be a conventional transesterification inhibitor in the art, such as a phosphorus-containing compound. Specific examples of transesterification inhibitors include phosphates, pyrophosphates, alkyl phosphates, phosphites, and the like.

[0032] In the present invention, the dispersant can be a conventional dispersant in the art, such as at least one of a mineral oil dispersant, a surfactant and an inorganic dispersant, specifically including but not limited to at least one of sodium lauryl sulfate, sodium dodecylbenzenesulfonate, dodecylacetic acid, dialkyl sulfosuccinate, polyoxyethylene alkylphenol ether, sorbitol alkylate, white oil, lubricating oil and polyphosphate.

[0033] According to a preferred embodiment of the present invention, the melt strength of the polyglycolic acid material at 235°C is 5 to 200 cN, for example, 5 cN, 8 cN, 9 cN, 15 cN, 20 cN, 25 cN, 30 cN, 35 cN, 50 cN, 60 cN, 70 cN, 80 cN, 100 cN, 150 cN, 200 cN, or any range thereof, preferably 8 to 100 cN. Using the above embodiment, the polyglycolic acid foam material has even better performance.

[0034] According to a preferred embodiment of the present invention, the melt flow rate of the polyglycolic acid material at 230°C / 2.16kg is not higher than 20.0g / 10min, for example, it can be 0.01-20.0g / 10min, 0.5g / 10min, 1.0g / 10min, 2.0g / 10min, 3.0g / 10min, 4.0g / 10min, 5.0g / 10min, 6.0g / 10min, 7.0g / 10min, 8.0g / 10min, 9.0g / 10min g / 10min, and any interval consisting of any of the foregoing values, preferably 0.01 to 20.0 g / 10min, and more preferably 0.5 to 10.0 g / 10min.

[0035] In the present invention, the term "homogeneous continuous phase" means that the volume proportion of the main phase of the polyglycolic acid material is not less than 95%, preferably not less than 99%, and its phase structure is continuous. The phase structure can be determined by methods well known in the art, for example: after the sample is quenched at low temperature, its cross-section is observed by scanning electron microscopy.

[0036] According to a preferred embodiment of the present invention, the polyglycolic acid material comprises a polyglycolic acid graft copolymer and a polyglycolic acid homopolymer. The polyglycolic acid foam material in the aforementioned embodiment has a lower density.

[0037] According to a more preferred embodiment of the present invention, the main chain of the polyglycolic acid graft copolymer contains at least a segment A1 represented by formula (IA1), and the side chain of the polyglycolic acid graft copolymer contains at least a segment B1 represented by formula (IB1), and the segment A1 and the segment B1 are connected through a linking site;

[0038]

[0039] In formula (IA1) and formula (IB1), * represents a linking site.

[0040] According to a more preferred embodiment of the present invention, the degree of polymerization p of segment B1 is not less than 40, preferably not less than 50, and preferably 70-2000.

[0041] According to a more preferred embodiment of the present invention, the sum of the degrees of polymerization of all segments on the main chain of the polyglycolic acid graft copolymer is not less than 50, for example, it can be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600 80, 390, 400, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, preferably 50-6000, more preferably 200-2500.

[0042] According to a more preferred embodiment of the present invention, the main chain of the polyglycolic acid graft copolymer further contains one or more of a segment A2 represented by formula (IA2), a segment A3 represented by formula (IA3), and a segment A4 represented by formula (IA4);

[0043]

[0044] According to a more preferred embodiment of the present invention, based on the total degree of polymerization of all segments on the main chain of the polyglycolic acid graft copolymer, the degree of polymerization of segment A4 may account for 0% to 50%.

[0045] According to a more preferred embodiment of the present invention, based on the total degree of polymerization of segment A1, segment A2 and segment A3, the degree of polymerization of segment A2 accounts for 0% to 32%.

[0046] In the present invention, the structural units in the main chain of the polyglycolic acid graft copolymer can be random copolymerization or block copolymerization. The specific copolymerization method is not particularly limited. Based on the difficulty of preparation, random copolymerization is generally used. According to an exemplary embodiment of the present invention, the polyglycolic acid graft copolymer has a structure shown in formula (I),

[0047]

[0048] In formula (I), x, y1, y2, z and p each independently represent the degree of polymerization. Specifically, x and p each independently represent a number greater than zero, y1, y2 and z each independently represent a number zero or greater than zero, the sum of x, y1, y2 and z is not less than 50, preferably 50 to 6000, more preferably 200 to 2500; p is not less than 40, preferably not less than 50, more preferably 70 to 2000; z accounts for 0% to 50% of the sum of x+y1+y2+z; y1 accounts for 0% to 32% of the sum of x+y1+y2.

[0049] In the present invention, when the polyglycolic acid graft copolymer contains a segment A4 (in formula (I), z is not 0), that is, the main chain of the polyglycolic acid graft copolymer contains an ethylene-vinyl alcohol copolymer segment, at this time, based on the sum of the polymerization degrees of all segments on the main chain of the polyglycolic acid graft copolymer, the polymerization degree of the segment A4 may account for 1% to 50% (in formula (I), the proportion of z to the sum of x+y1+y2+z), for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50%, preferably 20% to 45%, segment A The proportion of the degree of polymerization of 2 can be 0.1%-6.0% (the proportion of y1 to the sum of x+y1+y2 in formula (I), for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9% or 6.0%.

[0050] In the present invention, when the polyglycolic acid graft copolymer contains segment A2 (in formula (I), y1 is not 0) and does not contain segment A4 (in formula (I), z is 0), that is, the main chain of the polyglycolic acid graft copolymer contains a polyvinyl alcohol segment, in this case, based on the sum of the degrees of polymerization of all segments on the main chain of the polyglycolic acid graft copolymer, the proportion of the degree of polymerization of segment A2 (the ratio of y1 to the sum of x+y1+y2 in formula (I)) can be 1% to 32%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31% or 32%.

[0051] In the present invention, the sum of the degrees of polymerization of segments A1, A2, A3, and A4 (the sum of x+y1+y2+z in formula (I)) is the (total) degree of polymerization of the polyvinyl alcohol providing the polyethanol segment and / or the ethylene-vinyl alcohol copolymer providing the ethylene-vinyl alcohol copolymer segment. As known to those skilled in the art, the degree of polymerization can be obtained based on information such as the number average molecular weight of the polyvinyl alcohol or ethylene-vinyl alcohol copolymer and the alcoholysis degree of the raw material. The proportion of segment A4 (the proportion of z to the sum of x+y1+y2+z in formula (I)) is the content of the ethylene segment, which is generally a known parameter of the raw material product and can also be calculated by the integrated area of the corresponding characteristic peak in the nuclear magnetic resonance spectroscopy.

[0052] In the present invention, for polyvinyl alcohol, the ratio of the total degree of polymerization of segment A1 and segment A3 to the total degree of polymerization of segment A1, segment A2 and segment A3 (in formula (I), the ratio of x+y2 to the sum of x+y1+y2) is the alcoholysis degree of polyvinyl alcohol.

[0053] In the present invention, for the ethylene-vinyl alcohol copolymer, the ratio of the total degree of polymerization of segment A1 and segment A3 to the total degree of polymerization of segments A1, A2 and A3 (in formula (I), the ratio of x+y2 to the sum of x+y1+y2) is the alcoholysis degree of the ethylene-vinyl alcohol copolymer.

[0054] In the present invention, the alcoholysis degree is usually a known parameter of the raw material product, but can also be measured by nuclear magnetic resonance, infrared, near infrared and other detection methods.

[0055] In the present invention, segment B1 is a polyglycolic acid chain, and the degree of polymerization p of the polyglycolic acid chain can be calculated by the following formula (a):

[0056] p = (M2-M0) / (x*M m ) (a)

[0057] In the above formula (a), M2 and M0 are the number average molecular weight of the polyglycolic acid graft copolymer and the number average molecular weight of the raw material (e.g., polyvinyl acid and / or ethylene-vinyl alcohol copolymer) providing the segments of the polyglycolic acid graft copolymer main chain, respectively, in g / mol; x is the degree of polymerization of segment A1 (corresponding to x in formula (I)), which can be determined by detection methods such as nuclear magnetic resonance detection methods; M m To provide the molecular weight of segment B1, for example, when the monomer is glycolide, M m It is 58g / mol.

[0058] In the present invention, optionally, the lower limit of the p-value can be calculated by the following formula (b):

[0059] p > (M2-M0) / [(x+y2)*M m ] (b)

[0060] In the above formula (b), M2, M0 and M m As described above with respect to formula (a); x+y2 is the degree of polymerization of the hydroxyl-containing segments in the segments providing the main chain of the polyglycolic acid graft copolymer (in formula (I), the degree of polymerization of the hydroxyl-containing segments in segments A1 and A3 is provided), and its value can be calculated from the degree of alcoholysis, ethylene content and total degree of polymerization, and the calculation method is alcoholysis degree*(1-ethylene content)*total degree of polymerization.

[0061] In the present invention, when the polyglycolic acid material contains only polyglycolic acid graft copolymers, the value of p can optionally be obtained in the following manner: the polyglycolic acid material is fully hydrolyzed (i.e., the polyglycolic acid chains are completely hydrolyzed into small molecules), the raw materials providing the main chain are collected and their structures are characterized, and the value of p is then obtained in the manner disclosed in the present invention. For example, the polyglycolic acid material can be placed in water at 60-80°C until it is fully hydrolyzed (i.e., the polyglycolic acid chains are completely hydrolyzed into small molecules), and then the water is removed by means of reduced pressure distillation, vacuum freeze drying, or physical adsorption; the residue is dissolved in a solvent such as dimethyl sulfoxide, and then the raw materials providing the main chain are separated (e.g., by chromatography, etc.) and their structures are characterized; the number average molecular weight and hydroxyl content (x+y2 value) of the raw materials providing the main chain are obtained, and the value of p is obtained in the manner disclosed in the present invention.

[0062] According to the embodiments of the present invention, the p values of the obtained polyglycolic acid compositions calculated by formula (b) are all greater than 40.

[0063] According to a preferred embodiment of the present invention, the polyglycolic acid homopolymer has a structure shown in formula (II):

[0064]

[0065] In formula (II), i is directly connected to R The number of i is greater than or equal to 1, preferably any integer between 1 and 20, for example, it can be 1, 2, 3, 4, 5 or 6, more preferably 1 to 6; n2, ..., n i Each is the degree of polymerization, preferably n1, n2, ..., n i The sum of is 100 to 5000, preferably 1000 to 4000; M i For imino (-NH-), nitro or an ether bond (-O-); R is hydrogen, an aliphatic group or an aromatic group; R is hydrogen, a hydrocarbon group or an aromatic group, preferably hydrogen, an alkyl group with a molecular weight of 14 to 1000 g / mol or an aromatic hydrocarbon group with a molecular weight of 14 to 1000 g / mol.

[0066] In the present invention, in formula (II), when i>1, M1, M2, ..., M i Different or the same between n1, n2, ..., n i Different or the same.

[0067] In the present invention, formula (II), n1, n2, ..., n i The sum of the number average molecular weight of the polyglycolic acid homopolymer can be obtained by dividing the number average molecular weight of the polyglycolic acid homopolymer by the molecular weight of the repeating unit by GPC.

[0068] In the present invention, the degree of polymerization of each structural unit / segment is an average value, which is rounded off during calculation.

[0069] According to a preferred embodiment of the present invention, when the main chain of the copolymer contains segment A2, relative to 100 parts by mass of segment B1 in the polyglycolic acid graft copolymer and segment B2 in the polyglycolic acid homopolymer, The total amount of segment A1, segment A2 and segment A3 in the polyester graft copolymer is 0.001 to 5 parts by mass, for example, 0.001 part, 0.002 part, 0.003 part, 0.004 part, 0.005 part, 0.006 part, 0.007 part, 0.008 part, 0.009 part, 0.010 part, 0.011 part, 0.012 part, 0.013 part, 0.014 part, 0.015 part, 0.016 part, 0.017 part, 0.018 part, 0.019 part, 0.020 part, 0.021 part, 0.022 part, 0.023 part, 0.024 part, 0.025 part, 0.026 part, 0.027 part, 0.028 part, 0.029 part, 0.9 parts, 0.030 parts, 0.035 parts, 0.040 parts, 0.050 parts, 0.060 parts, 0.070 parts, 0.080 parts, 0.090 parts, 0.10 parts, 0.11 parts, 0.12 parts, 0.13 parts, 0.14 parts, 0.15 parts, 0.16 parts, 0.17 parts, 0.18 parts, 0.19 parts, 0.20 parts, 0.30 parts, 0.40 parts, 0.50 parts, 0.60 parts, 0.70 parts, 0.80 parts, 0.90 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts or 5.0 parts, preferably 0.005 to 3 parts by mass, preferably 0.005 to 1 part by mass, more preferably 0.01 to 1 part by mass.

[0070] According to a preferred embodiment of the present invention, when the main chain of the copolymer contains segment A4, relative to 100 parts by mass of segment B1 in the polyglycolic acid graft copolymer and segment B2 in the polyglycolic acid homopolymer, The total amount of segment A1, segment A3 and segment A4 in the polyester graft copolymer is 0.001 to 10 parts by mass, for example, 0.001 part, 0.002 part, 0.003 part, 0.004 part, 0.005 part, 0.006 part, 0.007 part, 0.008 part, 0.009 part, 0.010 part, 0.011 part, 0.012 part , 0.013 parts, 0.014 parts, 0.015 parts, 0.016 parts, 0.017 parts, 0.018 parts, 0.019 parts, 0.020 parts, 0.021 parts, 0.022 parts, 0.023 parts, 0.024 parts, 0.025 parts, 0.026 parts, 0.027 parts, 0.028 parts, 0.029 parts, 0.030 parts, 0.03 5 parts, 0.040 parts, 0.050 parts, 0.060 parts, 0.070 parts, 0.080 parts, 0.090 parts, 0.10 parts, 0.11 parts, 0.12 parts, 0.13 parts, 0.14 parts, 0.15 parts, 0.16 parts, 0.17 parts, 0.18 parts, 0.19 parts, 0.20 parts, 0.30 parts, 0.40 parts, 0.50 parts, 0. 60 parts, 0.70 parts, 0.80 parts, 0.90 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 5.0 parts, 6.0 parts, 7.0 parts, 8.0 parts, 9.0 parts or 10.0 parts, preferably 0.002 to 8 parts by mass, preferably 0.005 to 7 parts by mass, more preferably 0.01 to 5 parts by mass.

[0071] According to a preferred embodiment of the present invention, in the polyglycolic acid material, the content of the polyglycolic acid graft copolymer is 0.1 mass % to 80.0 mass %, relative to the total mass of the polyglycolic acid graft copolymer and the polyglycolic acid homopolymer, for example, it can be 1.0 mass %, 2.0 mass %, 3.0 mass %, 4.0 mass %, 5.0 mass %, 6.0 mass %, 7.0 mass %, 8.0 mass %, 9.0 mass %, 10 mass %, 11 mass %, 12 mass %, 13 mass %, 14 mass %, 15 mass %, 16 mass %, 17 mass %, 18 mass %, 19 mass %, 20 mass %, 21 mass %, 22 mass %, 23 mass %, 24 mass %, 25 mass %, 26 mass %, 27 mass %, 28 mass %, 29 mass %, 30.0 mass %, 35 mass %, 40 mass %, 45 mass %, 50 mass % or 55 mass %, preferably 0.5 mass % to 55.0 mass %, more preferably 1.0 mass % to 30.0 mass %.

[0072] According to a preferred embodiment of the present invention, in the polyglycolic acid material, parts by mass.

[0073] According to a preferred embodiment of the present invention, in the polyglycolic acid material, the content of the polyglycolic acid homopolymer is 20% to 99.9% by mass, relative to the total mass of the polyglycolic acid graft copolymer and the polyglycolic acid homopolymer, for example, 20% by mass, 25.0% by mass, 30.0% by mass, 35.0% by mass, 40.0% by mass, 45.0% by mass, 50.0% by mass, 55.0% by mass, 60.0% by mass, 65.0% by mass, 70.0% by mass, 71.0% by mass, 72.0% by mass, 73.0% by mass, 74.0% by mass, 75.0% by mass, 76.0% by mass, 77.0% by mass, %, 78.0 mass%, 79.0 mass%, 80.0 mass%, 81.0 mass%, 82.0 mass%, 83.0 mass%, 84.0 mass%, 85.0 mass%, 86.0 mass%, 87.0 mass%, 88.0 mass%, 89.0 mass%, 90.0 mass%, 91.0 mass%, 92.0 mass%, 93.0 mass%, 94.0 mass%, 95.0 mass%, 96.0 mass%, 97.0 mass%, 98.0 mass%, 99.0 mass% or 99.5 mass%, preferably 45.0 mass% to 99.5 mass%, more preferably 70.0 mass% to 99.0 mass%.

[0074] In the present invention, the mass content of each segment / structure / polymer chain in the polymer can be measured using methods known in the art, such as nuclear magnetic resonance and / or infrared methods. Alternatively, the mass content of each segment / structure / polymer chain can be calculated based on the amount of material added during the preparation process.

[0075] In the present invention, the term "multimodal molecular weight distribution" refers to that the GPC curve obtained when the polyglycolic acid material is subjected to GPC measurement has the characteristics of multimodal molecular weight distribution, indicating that it contains at least two polymer components with different molecular weights.

[0076] According to a preferred embodiment of the present invention, the number of peaks in the molecular weight distribution of the polyglycolic acid material is 2 to 4.

[0077] In the present invention, the peak molecular weight M in the molecular weight distribution curve is p Greater than 500,000 g / mol (i.e., the peak value in the GPC curve) w ) greater than 5.7) is at least 1, for example 1, 2 or 3, and the peak molecular weight M p Less than 500,000 g / mol (i.e., the peak value in the GPC curve) w ) is less than 5.7) is at least 1, for example 1.

[0078] According to the present invention, the molecular weight distribution curve and the number of peaks in the molecular weight distribution curve can be detected by gel permeation chromatography (GPC). The molecular weight distribution peak is the peak in the GPC curve at the weight average molecular weight (M w ) is greater than 10,000 g / mol (i.e. lg(M w ) is greater than 4.0) where the first derivative is zero and the second derivative is less than zero.

[0079] According to a preferred embodiment of the present invention, the molecular weight of the polyglycolic acid graft copolymer is higher than that of the polyglycolic acid homopolymer. That is, when the GPC curve has a bimodal molecular weight distribution, the higher molecular weight peak is the polyglycolic acid graft copolymer, and the lower molecular weight peak is the polyglycolic acid homopolymer.

[0080] In the present invention, when comparing the molecular weights of the polyglycolic acid graft copolymer and the polyglycolic acid homopolymer, the same type of molecular weight, such as the weight average molecular weight M w V s , weight average molecular weight M w Or number average molecular weight M n V s .Number average molecular weight M n .

[0081] According to a preferred embodiment of the present invention, the weight average molecular weight of the polyglycolic acid graft copolymer is 500,000 to 10 million g / mol, for example, it can be 500,000 g / mol, 1 million g / mol, 1.5 million g / mol, 2 million g / mol, 3 million g / mol, 4 million g / mol, 5 million g / mol, 6 million g / mol, 7 million g / mol or 10 million g / mol, preferably 1 million to 7 million g / mol, more preferably 1 million to 6 million g / mol.

[0082] According to a preferred embodiment of the present invention, the molecular weight polydispersity index of the polyglycolic acid graft copolymer is 1.0 to 3.0, for example, it can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, 2.0, 2.3, 2.4, 2.6, 2.8 or 3.0, preferably 1.1 to 1.5

[0083] According to a preferred embodiment of the present invention, the weight-average molecular weight of the polyglycolic acid homopolymer is 50,000 to 350,000 g / mol, for example, it can be 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 120,000 g / mol, 140,000 g / mol, 160,000 g / mol, 180,000 g / mol, 200,000 g / mol, 220,000 g / mol, 240,000 g / mol, 260,000 g / mol, 280,000 g / mol, 300,000 g / mol, 320,000 g / mol, 330,000 g / mol, 340,000 g / mol or 350,000 g / mol, preferably 100,000 to 200,000 g / mol.

[0084] According to a preferred embodiment of the present invention, the molecular weight polydispersity index of the weight average molecular weight of the polyglycolic acid homopolymer is 1.0 to 3.0, for example, it can be 1.0, 1.2, 1.4, 1.5, 1.6, 1.8, 2.1, 2.3, 2.6, 2.9 or 3.0, preferably 1.4 to 2.9.

[0085] According to a preferred embodiment of the present invention, the overall weight-average molecular weight of the polyglycolic acid material is 180,000 to 1.5 million g / mol, for example, 180,000 g / mol, 190,000 g / mol, 200,000 g / mol, 210,000 g / mol, 220,000 g / mol, 230,000 g / mol, 240,000 g / mol, 250,000 g / mol, 300,000 g / mol, 350,000 g / mol, 400,000 g / mol, 450,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, 800,000 g / mol, 900,000 g / mol, 1,000,000 g / mol, 1,100,000 g / mol, 1,200,000 g / mol, 1,300,000 g / mol, 1,400,000 g / mol or 1,500,000 g / mol, preferably 200,000 to 1,500,000 g / mol, and more preferably 250,000 to 500,000 g / mol.

[0086] According to a preferred embodiment of the present invention, the overall molecular weight polydispersity index of the polyglycolic acid material is 1.5 to 20.0, for example, it can be 1.5, 1.8, 2.0, 2.5, 3.6, 4.3, 5.3, 6.0, 8.2, 10.3, 12.0, 13.5, 14.5, 16, 18.2, 19.0, 20.0, preferably 2.0 to 12.0, preferably 2.0 to 6.0, and more preferably 2.0 to 3.5.

[0087] According to a preferred embodiment of the present invention, the density of the polyglycolic acid foam material is not greater than 1.45 g / cm 3 , for example 0.8 g / cm 3 , 0.83g / cm3 , 0.90g / cm 3 , 0.98g / cm 3 , 1.00g / cm 3 , 1.14g / cm 3 ,,1.20g / cm 3 , 1.31g / cm 3 , 1.45g / cm 3 , and the range of any two values above, preferably not more than 1.20g / cm 3 , further preferably not more than 1.00 g / cm 3 .

[0088] According to a preferred embodiment of the present invention, the pore size of the polyglycolic acid foam material is 5 to 500 μm, preferably 10 to 300 μm.

[0089] In the present invention, the cell size can be measured by photographing the cross section using a scanning electron microscope.

[0090] In the present invention, the total weight average molecular weight, overall number average molecular weight, overall molecular weight polydispersity index, number of molecular weight distribution peaks, mass fraction of each component in the polymer, etc. can be detected by gel permeation chromatography (GPC). The specific detection method is generally known in the art, and conventional detection parameters can be used. For example, the following method can be used: the testing instrument is a PL-GPC50 gel permeation chromatograph from Angilent, USA, and the processing software is GPC offline; during the test, the mobile phase is hexafluoroisopropanol containing 5 mmol / L sodium trifluoroacetate, the flow rate is 1 mL / min, the column temperature is 40°C, the injection volume is 100 μL, the standard sample is PMMA, and the sample concentration is 1 mg / mL. The specific values of the above parameters are obtained according to analytical methods known in the art.

[0091] There is no particular limitation on the preparation method of the polyglycolic acid material in the present invention. The raw materials capable of providing the various chain segments of the polyglycolic acid material in the present invention can be selected and prepared by the existing polymerization preparation method in the art.

[0092] According to a preferred embodiment of the present invention, the polyglycolic acid material is prepared by the following method: a monomer capable of polymerizing to obtain polyglycolic acid segments, polyvinyl alcohol and / or ethylene-vinyl alcohol copolymer as a macroinitiator, and optionally a small molecule co-initiator are melt polymerized in the presence of a catalyst and an optional antioxidant. The following examples of the present invention respectively illustrate two specific operating procedures using polyvinyl alcohol and ethylene-vinyl alcohol copolymer as macroinitiators, which should not be construed by those skilled in the art as limiting the present invention.

[0093] In the present invention, a homogeneous continuous phase polyglycolic acid material with multimodal molecular weight distribution can be formed in situ simultaneously.

[0094] According to the present invention, the monomer can be selected from a wide range. In a preferred embodiment of the present invention, the monomer includes at least one of methyl glycolate, glycolic acid, and glycolide, and more preferably glycolide.

[0095] According to a preferred embodiment of the present invention, the alcoholysis degree of the polyvinyl alcohol is 68-99%.

[0096] According to a preferred embodiment of the present invention, the degree of polymerization of the polyvinyl alcohol is 100 to 6000, preferably 300 to 2000.

[0097] According to a preferred embodiment of the present invention, the content of ethylene segments in the ethylene-vinyl alcohol copolymer is 0 mol%-50 mol%, and is not 0 mol%.

[0098] According to a preferred embodiment of the present invention, the degree of polymerization of the ethylene-vinyl alcohol copolymer is 50 to 6000, preferably 300 to 2000.

[0099] According to a preferred embodiment of the present invention, the melt flow rate of the ethylene-vinyl alcohol copolymer at 190° C. / 2.16 kg is 0.1 to 50.0 g / 10 min.

[0100] In the present invention, the small molecule co-initiator can be selected from a wide range. Preferably, the small molecule co-initiator is a compound having initiator function and capable of providing an imino group, a nitro group, or an ether bond. Preferably, the molecular co-initiator is a small molecule substance containing a hydroxyl group or an amino group with a boiling point greater than 160°C, preferably with a molecular weight of no more than 1000 g / mol, preferably 60 to 300 g / mol. Examples include, but are not limited to, 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.

[0101] According to a preferred embodiment of the present invention, the content of hydroxyl groups contained in the macroinitiator is 0.1 μmol / g monomer to 1.5 mmol / g monomer per gram of monomer, preferably 0.5 μmol / g monomer to 1.0 mmol / g monomer, and more preferably 1.0 μmol / g monomer to 0.5 mmol / g monomer.

[0102] According to a preferred embodiment of the present invention, the active hydrogen content of the small molecule co-initiator is 3.0 μmol / g monomer to 40.0 μmol / g monomer, preferably 10.0 μmol / g monomer to 30.0 μmol / g monomer, calculated as active hydrogen per gram of monomer.

[0103] According to a particularly preferred embodiment of the present invention, the total active hydrogen content of the macromolecular initiator and the small molecule co-initiator is 3.1 μmol / g monomer to 1.54 mmol / g monomer per gram of monomer, preferably 10.5 μmol / g monomer to 1.03 mmol / g monomer, and more preferably 11.0 μmol / g monomer to 530.0 μmol / g monomer, calculated as active hydrogen.

[0104] In the present invention, "active hydrogen" refers to hydrogen contained in water, hydroxyl groups (-OH), primary amino groups (-NH2) and secondary amino groups (-NH-). According to the present invention, each water molecule contains one "active hydrogen".

[0105] According to a preferred embodiment of the present invention, the amount of the macromolecular initiator used relative to 100 parts of monomers, when the macromolecular initiator contains polyvinyl alcohol, the polyvinyl alcohol is 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass, preferably 0.005 to 1 parts by mass, more preferably 0.01 to 1 parts by mass; when the macromolecular initiator contains ethylene-vinyl alcohol copolymer, the ethylene-vinyl alcohol copolymer is 0.001 to 10 parts by mass, preferably 0.002 to 8 parts by mass, preferably 0.005 to 7 parts by mass, more preferably 0.01 to 5 parts by mass.

[0106] According to a preferred embodiment of the present invention, the amount of the small molecule co-initiator is 0.001 to 1 part, preferably 0.01 to 0.1 part, relative to 100 parts of the monomer, by mass.

[0107] According to a preferred embodiment of the present invention, when preparing polyglycolic acid material, the conditions of melt polymerization include: temperature of 120-300°C, preferably 160-250°C, more preferably 200-240°C, and reaction time of 0.5-60 min, preferably 1-10 min.

[0108] In the present invention, when preparing the polyglycolic acid material, the apparatus for melt polymerization can be a conventional melt mixing apparatus in the art, such as a continuous twin-screw extruder. Preferably, when a continuous twin-screw extruder is used for melt polymerization, the conditions include: a temperature of 180 to 250°C, preferably 210 to 240°C; and / or a screw speed of 5 to 300 rpm, preferably 40 to 150 rpm; and / or an aspect ratio of 25 to 80, preferably 40 to 70.

[0109] In the present invention, the apparatus for performing melt polymerization may be a single apparatus or a plurality of apparatuses connected in series.

[0110] In the present invention, when preparing the polyglycolic acid material, the catalyst can be a conventional catalyst in the art that can promote melt polymerization, such as an organic guanidine catalyst, a Sn-based catalyst, a Bi-based catalyst, a Mg-based catalyst, an Al-based catalyst, a Ca-based catalyst, a Fe-based catalyst, a Mn-based catalyst, a Ti-based catalyst, and a Zn-based catalyst.

[0111] In the present invention, when preparing the polyglycolic acid material, the specific amount of the catalyst used is sufficient to effectively carry out melt polymerization. Preferably, the amount of the catalyst used is 0.005 to 1 part, preferably 0.01 to 0.2 parts, based on mass, relative to 100 parts of the monomer.

[0112] In the present invention, when preparing the polyglycolic acid material, the added antioxidant can be a conventional antioxidant in the art. For example, the antioxidant mentioned above in the present invention is also suitable for the preparation of polyglycolic acid materials. The amount of the antioxidant can be selected within a wide range. Preferably, the amount of the antioxidant is 0 to 2 parts by mass, preferably 0.01 to 1 part by mass, relative to 100 parts of the monomer (phr).

[0113] In the present invention, a macromolecular initiator is used to initiate monomer polymerization, which can obtain a homogeneous continuous phase polyglycolic acid material with a multimodal molecular weight distribution. This material can meet the foaming requirements without further chemical modification. Therefore, on the one hand, there is no need to add chain extenders such as isocyanates that may have an impact on the environment. On the other hand, the preparation process undergoes one less heat treatment, thereby avoiding the oxidation and thermal degradation problems caused by repeated heat treatment of PGA. The density of the foamed material obtained after foaming is significantly reduced relative to the raw material, which not only increases the yield of products of the same quality, but also improves the thermal insulation properties of the obtained products, broadens the application scenarios of PGA, and provides more possible use markets.

[0114] A second aspect of the present invention provides a method for preparing the polyglycolic acid foam material, comprising: extruding and foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution in the presence of a foaming agent.

[0115] When a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution is prepared into a polyglycolic acid foam material, a foaming agent is often required. In the present invention, extrusion foaming is performed, and the foaming agent is generally a chemical foaming agent, which has low equipment requirements, low cost, and is simpler and easier to use.

[0116] According to a preferred embodiment of the present invention, the foaming agent is a compound that can generate gas due to thermal decomposition, and the thermal decomposition temperature is preferably 160°C to 260°C, more preferably 180°C to 240°C.

[0117] According to a preferred embodiment of the present invention, the foaming agent includes at least one of an azo compound, a nitroso compound and a hydrazide compound, preferably an azo compound, and more preferably an azo compound having a thermal decomposition temperature of 180 to 240°C.

[0118] According to a preferred embodiment of the present invention, the azo compound includes at least one of azodicarbonamide, barium azodicarboxylate, barium azodicarboxylate and potassium azodicarbonamide formate.

[0119] According to a preferred embodiment of the present invention, the nitroso compound comprises at least one of dinitrosopentamethylenetetramine and trinitrosotrimethylenetriamine.

[0120] According to a preferred embodiment of the present invention, the hydrazide compound is at least one selected from oxalohydrazide, nitroguanidine, 4,4'-oxybisbenzenesulfonylhydrazide, p-toluenesulfonylsemicarbazide, 4,4'-oxybisbenzenesulfonylsemicarbazide and trihydrazine triazine.

[0121] The conditions for extrusion foaming in the present invention can be conventionally selected in the field, and the specific process is known to those skilled in the art. For example, the equipment for extrusion foaming is a single-screw extruder or a twin-screw extruder, and the screw speed is preferably 5 to 200 rpm, preferably 15 to 100 rpm, and the extrusion temperature is preferably 200 to 260° C., preferably 220 to 245° C.

[0122] The third aspect of the present invention provides the use of the polyglycolic acid foam material in surgical drug carriers, orthopedic fixation, tissue repair, foamed disposable products and thermal insulation materials.

[0123] In the present invention, the polyglycolic acid foam material of the present invention broadens the application scenarios of PGA compared to unfoamed raw materials and provides more possible application markets.

[0124] The present invention will be described in detail below by way of examples. The relevant data were obtained by the following test methods:

[0125] Gel Permeation Chromatography (GPC): Testing was performed on a PL-GPC50 gel permeation chromatograph (Angilent, USA), using GPC offline software. The mobile phase consisted of hexafluoroisopropanol containing 5 mmol / L sodium trifluoroacetate, at a flow rate of 1 mL / min, a column temperature of 40°C, and an injection volume of 100 μL. The standard sample was PMMA, with a sample concentration of 1 mg / mL.

[0126] Melt flow rate measurement: Tests were conducted on a CEAST MF20 melt flow tester (Instron, USA). The test temperature was 230°C, the load was 2.16 kg, and the preheating time was 4 minutes.

[0127] Melt strength testing: The test was conducted on a Rosand RH7 high-pressure capillary rheometer from Malvern Panalytical (China), using the Haul Off model (2.0 mm diameter, 20 mm length). The barrel push rod downward speed was 15 mm / min, the test temperature was 235°C, the initial draw-off speed of the winder was 3 m / min, and the final draw-off speed was 50 m / min. The speed increased at a constant rate over a 3-minute ramp-up period, and 30 data points were collected.

[0128] Particle density test method: The test is conducted using an electronic hydrometer SD-200L manufactured by Alfa Mirage, Japan. The test method utilizes the Archimedes principle and complies with JIS K6530 for rubber and JIS K7112 for plastics. The test method is as follows: First, measure the particle's weight in air (m1), then measure its weight in liquid (water or ethanol, etc.) (m2). The particle density is calculated using the following formula:

[0129]

[0130] The parts in the following examples and comparative examples are all parts by weight.

[0131] In the following examples and comparative examples, the materials used are as follows:

[0132] In the following examples, unless otherwise specified, all raw materials used are commercially available products.

[0133] Glycolide was purchased from Shenzhen Boli Biomaterial Co., Ltd. with a purity of ≥99.5%, a moisture content of ≤500 ppm, and an acid value of ≤3 mmol / kg.

[0134] Stannous octoate, 1,4-butanediol (BDO), and serinol were purchased from Sinopharm Chemical Reagent Co., Ltd. The purity of stannous octoate and serinol was AR grade, and the purity of 1,4-butanediol was CP grade.

[0135] Antioxidant 1010 was purchased from BASF (China) Co., Ltd., and antioxidant 626 was purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with a purity of ≥95%.

[0136] Polyvinyl alcohol (PVA) was purchased from Chongqing Chuanwei Chemical Co., Ltd. of Sinopec Group with a brand name of 0588, a degree of polymerization of about 500, and a degree of alcoholysis of about 88%.

[0137] Ethylene-vinyl alcohol copolymer (EVOH) was purchased from Kuraray Co., Ltd., Japan, under the designation EVAL™ H171B. Its ethylene content was 38 mol%, its melt flow rate at 190°C / 2.16 kg was 1.7 g / 10 min, its number-average molecular weight was approximately 18,000 g / mol, its total degree of polymerization was approximately 480, and its hydroxyl content was approximately 0.01 mol / g EVOH.

[0138] Polyglycolide (PGA) was purchased from Shenzhen Boli Biomaterial Co., Ltd., with a melt mass flow rate of 13 g / 10 min at 230°C / 2.16 kg.

[0139] White oil (brand: ISO VG 46) was purchased from SKALN Group Co., Ltd.; azodicarbonamide and p-toluenesulfonyl semicarbazide were purchased from Beijing Wokai Biotechnology Co., Ltd. with purities of 97% and 95%, respectively; 4,4'-Oxo-bis(phenylsulfonyl)semicarbazide and trihydrazino-s-triazine were purchased from Beijing Mairida Technology Co., Ltd. with purities of 98% and 95%, respectively.

[0140] Polyglycolic acid material preparation example 1

[0141] Glycol (moisture content 260 ppm), stannous octoate, polyvinyl alcohol (PVA), 1,4-butanediol (BDO), antioxidant 1010, and antioxidant 626 were uniformly mixed in a mass ratio of 100:0.1:0.015:0.035:0.5:0.3 and pelletized using a Labtech parallel, co-rotating twin-screw extruder (screw diameter: 20 mm, aspect ratio: 40). The extruder consisted of 11 sections, numbered 1-11, from the feed port to the die. Section 1 served only for feeding and was not heated. The temperatures in sections 2-11 were 160°C, 200°C, 220°C, 220°C, 220°C, 220°C, 230°C, 235°C, and 240°C, respectively. The feed rate was 3 kg / h, the screw speed was 150 rpm, and the average residence time was approximately 3 minutes.

[0142] The hydroxyl content from PVA in the raw material is 2.69 μmol / g glycolide, the active hydrogen content in the small molecule initiator 1,4-butanediol is 7.78 μmol / g glycolide, and the active hydrogen content of water in the raw material is 14.44 μmol / g glycolide. The total active hydrogen content of the small molecule initiator is about 22.22 μmol / g glycolide.

[0143] GPC test results showed that the molecular weight of the resulting polyglycolic acid material exhibited a bimodal distribution. The overall number-average molecular weight of the polyglycolic acid material was 84,765 g / mol, and the weight-average molecular weight was 187,008 g / mol. The number-average molecular weight and weight-average molecular weight of the polyglycolic acid graft copolymer were 1,159,029 g / mol and 1,495,459 g / mol, respectively. The number-average molecular weight and weight-average molecular weight of the polyglycolic acid homopolymer were 81,009 g / mol and 118,984 g / mol, respectively. The weight-average molecular weight of the polyglycolic acid graft copolymer accounted for 7.93% of the total weight. According to formula (b) in the specification, the degree of polymerization (p) of the polyglycolic acid in the graft copolymer was >44.

[0144] The melt flow rate test shows that the melt mass flow rate of the obtained polyglycolic acid material measured at 230°C / 2.16kg is 9.9g / 10min.

[0145] The melt strength test showed that the melt strength of the obtained polyglycolic acid material was 20 cN at 235°C.

[0146] Polyglycolic acid material preparation example 2

[0147] The method of preparing polyglycolic acid material in Example 1 is followed, except that polyvinyl alcohol (PVA) is replaced by ethylene-vinyl alcohol copolymer (EVOH), and the ratio of glycolide (water content 200 ppm), stannous octoate, EVOH, 1,4-butanediol, antioxidant 1010 and antioxidant 626 is set to 100:0.1:0.015:0.035:0.3:0.6.

[0148] The hydroxyl content from EVOH in the raw material is 2.46 μmol / g glycolide, the active hydrogen content in the small molecule initiator 1,4-butanediol in the raw material is 7.78 μmol / g glycolide, and the active hydrogen content of water in the raw material is 11.11 μmol / g glycolide. The total active hydrogen content of the small molecule initiator is about 18.89 μmol / g glycolide.

[0149] GPC test results showed that the molecular weight of the resulting polyglycolic acid material exhibited a bimodal distribution. The overall number-average molecular weight of the polyglycolic acid material was 128,236 g / mol, and the weight-average molecular weight was 268,237 g / mol. The number-average molecular weight and weight-average molecular weight of the polyglycolic acid graft copolymer were 1,805,926 g / mol and 2,011,475 g / mol, respectively, while the number-average molecular weight and weight-average molecular weight of the polyglycolic acid homopolymer were 124,956 g / mol and 199,216 g / mol, respectively. The weight proportion of the polyglycolic acid graft copolymer was 7.42%. According to formula (b) in the specification, the degree of polymerization (p) of the polyglycolic acid in the graft copolymer was >103.

[0150] The melt flow rate test showed that the melt mass flow rate of the obtained polyglycolic acid composition measured at 230° C. / 2.16 kg was 5.4 g / 10 min.

[0151] The melt strength test showed that the melt strength of the polyglycolic acid composition was 9 cN at 235°C.

[0152] Comparative Preparation Example 1 of Polyglycolic Acid Material

[0153] The method of Example 1 was followed, except that polyvinyl alcohol (PVA) was not used, and the ratio of glycolide (water content 180 ppm), stannous octoate, 1,4-butanediol, antioxidant 1010 and antioxidant 626 was changed to 100:0.1:0.05:0.3:0.6

[0154] The active hydrogen content of the small molecule initiator 1,4-butanediol in the raw material is 11.11 μmol / g glycolide, and the active hydrogen content of water in the raw material is calculated as 10.0 μmol / g glycolide. The total active hydrogen content of the small molecule initiator is about 21.11 μmol / g glycolide.

[0155] GPC test results showed that the molecular weight distribution of the obtained polyglycolic acid material was unimodal, and the number average molecular weight and weight average molecular weight were 124873 g / mol and 197798 g / mol, respectively.

[0156] Preparation Examples and Comparative Examples of Polyglycolic Acid Foam Materials

[0157] Example 1

[0158] The polyglycolic acid material (melt strength at 235°C: 20 cN) obtained in Polyglycolic Acid Material Preparation Example 1, azodicarbonamide, and white oil were mixed uniformly in a mass ratio of 100:1:1 and extruded using a Eurolab parallel co-rotating twin-screw extruder (screw diameter: 16 mm, aspect ratio: 40) to obtain a polyglycolic acid foam material. The extruder had 11 sections from the feed port to the die, numbered 1 to 11. Section 1 served only for feeding and was not heated. The temperatures of sections 2 to 11 of the extruder were: 200°C, 230°C, 230°C, 230°C, 230°C, 240°C, 240°C, 240°C, 230°C, and 230°C, respectively. The screw speed was 80 rpm, and the feed rate was 1.5 kg / h.

[0159] The cross section of polyglycolic acid foam material was magnified 200 times by scanning electron microscopy. Figure 1 As shown by Figure 1 It can be seen that the pore size of the polyglycolic acid foam material is roughly distributed between 10 and 150 μm, and there are more pores.

[0160] The surface of polyglycolic acid foam material was magnified by 500 times using scanning electron microscopy. Figure 5 As shown by Figure 5 It can be seen that the surface of the polyglycolic acid foam material is relatively smooth and has no obvious holes.

[0161] Example 2

[0162] The preparation method is similar to that of Example 1, except that the amount of azodicarbonamide is increased to 2 parts by mass, and 0.3 parts by mass of antioxidant 1010 and 0.3 parts by mass of antioxidant 626 are additionally added, that is, the mass ratio of polyglycolic acid material (melt strength at 235°C: 20 cN), azodicarbonamide, and white oil is changed to polyglycolic acid material (melt strength at 235°C: 20 cN), azodicarbonamide, white oil, antioxidant 1010, and antioxidant 626 in a mass ratio of 100:2:1:0.3:0.3, and finally a polyglycolic acid foam material is prepared.

[0163] The cross section of polyglycolic acid foam material was magnified 200 times by scanning electron microscopy. Figure 2 As shown by Figure 2 It can be seen that the pore size of the polyglycolic acid foam material is roughly distributed between 20 and 200 μm, and there are more pores.

[0164] Example 3

[0165] The preparation method is similar to that of Example 2, except that the foaming agent azodicarbonamide is replaced with p-toluenesulfonyl semicarbazide, and finally a polyglycolic acid foam material is prepared.

[0166] The cross section of the polyglycolic acid foam material was magnified 200 times by scanning electron microscopy. Figure 3 As shown by Figure 3 It can be seen that the pore size of the polyglycolic acid foam material is roughly distributed between 5 and 150 μm, and the number of pores is relatively small.

[0167] Example 4

[0168] The preparation method is similar to that of Example 2, except that the foaming agent azodicarbonamide is replaced with 4,4'-oxybis(benzenesulfonyl)amino urea, and the polyglycolic acid material is replaced with the polyglycolic acid material in Polyglycolic Acid Material Preparation Example 2, and finally a polyglycolic acid foam material is prepared.

[0169] The pore size of polyglycolic acid foam material is approximately distributed between 10 and 150 μm, with relatively few pores.

[0170] Example 5

[0171] The preparation method is similar to that of Example 4, except that the foaming agent is changed to trihydrazino-s-triazine, and finally a polyglycolic acid foam material is prepared.

[0172] The pore size of polyglycolic acid foam material is approximately distributed between 10 and 150 μm, with relatively few pores.

[0173] Comparative Example 1

[0174] The preparation method is similar to that of Example 1, except that the polyglycolic acid material is replaced with the polyglycolic acid material in the polyglycolic acid comparative preparation example 1 (melt strength at 235° C.: 1 cN), and finally a polyglycolic acid foam material is prepared.

[0175] The pore size of polyglycolic acid foam material is approximately distributed between 10 and 50 μm, and the number of pores is very small.

[0176] Comparative Example 2

[0177] The preparation method is similar to that of Example 1, except that the polyglycolic acid material is replaced with commercially available pure polyglycolide (purchased from Shenzhen Boli Biomaterial Co., Ltd., with a melt mass flow rate of 13 g / 10 min at 230°C / 2.16 kg and a melt strength of 4 cN at 235°C).

[0178] The cross-section of polyglycolic acid foam material was magnified 200 times by scanning electron microscopy. Figure 4 As shown by Figure 4 It can be seen that the pore size of the polyglycolic acid foam material is roughly distributed between 30 and 100 μm, and the number of pores is relatively small.

[0179] The surface of polyglycolic acid foam material was magnified by 500 times using scanning electron microscopy. Figure 6 As shown by Figure 6 It can be seen that the surface of the polyglycolic acid foam material is relatively rough, and there are a large number of holes caused by the rupture of surface cells. This indicates that the commercially available pure polyglycolide is not sufficient to maintain a large number of large-sized cells during the foaming process, and it is difficult to obtain a foam material with lower density under the same foaming conditions.

[0180] Comparative Example 3

[0181] The preparation method is similar to that of Example 2, except that the foaming agent azodicarbonamide is not added, and unfoamed modified PGA particles are obtained.

[0182] Test Example 1

[0183] Density tests were performed on all embodiments and comparative examples, and the results are shown in Table 1.

[0184] Table 1

[0185]

[0186] From the results in Table 1, it can be seen that the polyglycolic acid material in the present invention can meet the melt strength requirements of chemical foaming without further chemical modification. Compared with the prior art PGA, it has certain advantages in the application field of PGA foam materials.

[0187] 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 polyglycolic acid foam material, characterized in that: The polyglycolic acid foaming material is prepared by foaming a foaming composition containing a homogeneous continuous phase polyglycolic acid material with multimodal molecular weight distribution.

2. The polyglycolic acid foam material according to claim 1, wherein The polyglycolic acid material has a melt strength of 5 to 200 cN at 235° C., preferably 8 to 100 cN; and / or, The melt flow rate of the polyglycolic acid material at 230° C. / 2.16 kg is not higher than 20.0 g / 10 min, preferably 0.01 to 20.0 g / 10 min, and more preferably 0.5 to 10.0 g / 10 min.

3. The polyglycolic acid foam material according to claim 1 or 2, wherein: The polyglycolic acid material contains a polyglycolic acid graft copolymer and a polyglycolic acid homopolymer; Preferably, the main chain of the polyglycolic acid graft copolymer contains at least a segment A1 represented by formula (IA1), and the side chain of the polyglycolic acid graft copolymer contains at least a segment B1 represented by formula (IB1), and the segment A1 and the segment B1 are connected through a linking site; In formula (IA1) and formula (IB1), * represents a linking site; More preferably, the degree of polymerization p of segment B1 is not less than 40, preferably not less than 50, more preferably 70 to 2000; and / or The total polymerization degree of all segments on the main chain of the polyglycolic acid graft copolymer is not less than 50, preferably 50 to 6000, more preferably 200 to 2500.

4. The polyglycolic acid foam material according to claim 3, wherein The main chain of the polyglycolic acid graft copolymer further contains one or more of a segment A2 represented by formula (IA2), a segment A3 represented by formula (IA3), and a segment A4 represented by formula (IA4); Preferably, based on the total degree of polymerization of all segments on the main chain of the polyglycolic acid graft copolymer, the degree of polymerization of segment A4 accounts for 0% to 50%; and / or, Based on the total degree of polymerization of segments A1, A2, and A3, the degree of polymerization of segment A2 accounts for 0% to 32%; More preferably, the polyglycolic acid graft copolymer has a structure represented by formula (I), In formula (I), x, y1, y2, z and p each independently represent a degree of polymerization.

5. The polyglycolic acid foam material according to claim 3 or 4, wherein The polyglycolic acid homopolymer has a structure shown in formula (II), In formula (II): i is directly connected to R The number of i is greater than or equal to 1, preferably any integer between 1 and 20, more preferably 1 to 6; n1,n2,……,n i Each is the degree of polymerization, preferably n1, n2, ..., n i The sum of is 100 to 5000, preferably 1000 to 4000; M i is an imino group, a secondary amino group or an ether bond; R is hydrogen, a hydrocarbon group or an aryl group, preferably hydrogen, an alkyl group with a molecular weight of 14 to 1000 g / mol or an aromatic hydrocarbon group with a molecular weight of 14 to 1000 g / mol.

6. The polyglycolic acid foam material according to claim 4 or 5, wherein When the main chain of the copolymer contains segment A2, relative to 100 parts by mass of segment B1 in the polyglycolic acid graft copolymer and segment B2 in the polyglycolic acid homopolymer, The total amount of segment A1, segment A2 and segment A3 in the polyester graft copolymer is 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass, preferably 0.005 to 1 part by mass, more preferably 0.01 to 1 part by mass; and / or, When the main chain of the copolymer contains segment A4, relative to 100 parts by mass of segment B1 in the polyglycolic acid graft copolymer and segment B2 in the polyglycolic acid homopolymer, The total amount of segment A1, segment A3 and segment A4 in the polyester graft copolymer is 0.001 to 10 parts by mass, preferably 0.002 to 8 parts by mass, preferably 0.005 to 7 parts by mass, more preferably 0.01 to 5 parts by mass; and / or, In the polyglycolic acid material, the content of the polyglycolic acid graft copolymer is 0.1% to 80.0% by mass, preferably 0.5% to 55.0% by mass, and more preferably 1.0% to 30.0% by mass, relative to the total mass of the polyglycolic acid graft copolymer and the polyglycolic acid homopolymer; and / or the content of the polyglycolic acid homopolymer is 20% to 99.9% by mass, preferably 45.0% to 99.5% by mass, and more preferably 70.0% to 99.0% by mass.

7. The polyglycolic acid foam material according to any one of claims 3 to 6, wherein: The number of peaks in the molecular weight distribution of the polyglycolic acid material is 2 to 4; and / or, The molecular weight of the polyglycolic acid graft copolymer is higher than the molecular weight of the polyglycolic acid homopolymer; Preferably, The weight average molecular weight of the polyglycolic acid graft copolymer is 500,000 to 10 million g / mol, preferably 1 million to 7 million g / mol, more preferably 1 million to 6 million g / mol; and / or, The molecular weight polydispersity index of the polyglycolic acid graft copolymer is 1.0 to 3.0, preferably 1.1 to 1.5; and / or, The weight average molecular weight of the polyglycolic acid homopolymer is 50,000 to 350,000 g / mol, preferably 100,000 to 200,000 g / mol; and / or, The molecular weight polydispersity index of the polyglycolic acid homopolymer is 1.0 to 3.0, preferably 1.4 to 2.

9.

8. The polyglycolic acid foam material according to any one of claims 1 to 7, wherein: The total weight average molecular weight of the polyglycolic acid material is 180,000 to 1.5 million g / mol, preferably 200,000 to 1.5 million g / mol, more preferably 250,000 to 500,000 g / mol; and / or, The overall molecular weight polydispersity index of the polyglycolic acid material is 1.5 to 20.0, preferably 2.0 to 12.0, preferably 2.0 to 6.0, more preferably 2.0 to 3.5; and / or, The density of the polyglycolic acid foam material is not greater than 1.45 g / cm 3 , preferably not more than 1.20 g / cm 3 , further preferably not more than 1.00 g / cm 3 and / or The cell size of the polyglycolic acid foam material is 5 to 500 μm, preferably 10 to 300 μm.

9. A method for preparing the polyglycolic acid foam material according to any one of claims 1 to 8, characterized in that: The preparation method comprises: extruding and foaming a foaming composition comprising a homogeneous continuous phase polyglycolic acid material having a multimodal molecular weight distribution in the presence of a foaming agent; Preferably, the equipment for extrusion foaming is a single-screw extruder or a twin-screw extruder, preferably the screw speed is 5 to 200 rpm, preferably 15 to 100 rpm, and the extrusion temperature is preferably 200 to 260° C., preferably 220 to 245° C.; Preferably, the foaming agent is a compound that can generate gas due to thermal decomposition, and the thermal decomposition temperature is preferably 160°C to 260°C, more preferably 180°C to 240°C; Preferably, the foaming agent comprises at least one of an azo compound, a nitroso compound and a hydrazide compound; More preferably, The azo compound includes at least one of azodicarbonamide, barium azodicarboxylate, barium azodicarboxylate and potassium azodicarbonamide formate; and / or, The nitroso compound comprises at least one of dinitrosopentamethylenetetramine and trinitrosotrimethylenetriamine; and / or, The hydrazide compound is at least one selected from oxalohydrazide, nitroguanidine, 4,4'-oxy-bisbenzenesulfonylhydrazide, p-toluenesulfonylsemicarbazide, 4,4'-oxy-bisbenzenesulfonylsemicarbazide and trihydrazine triazine; and / or, The foaming agent is an azo compound.

10. Use of the polyglycolic acid foam material according to any one of claims 1 to 8 in surgical drug carriers, orthopedic fixation, tissue repair, foamed disposable products and thermal insulation materials.

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