Preparation method of polyglycolic acid composition, composition and application

Abstract

The invention discloses a preparation method of a polyglycolic acid composition, the composition and application, and relates to the technical field of polymer synthesis, the preparation method of the polyglycolic acid composition comprises the following steps: step 1) carrying out normal pressure condensation polymerization on components including a hydroxy acid monomer, a small molecule initiator, a large molecule initiator and a catalyst; and step 2) continuously performing reduced pressure polycondensation reaction on the reaction system in the step 1) to prepare the polyglycolic acid composition. The polyglycolic acid composition provided by the invention can be prepared in a simple, green and low-cost manner by introducing a macromolecular initiator into a polymerization system, the overall molecular weight and melt viscosity of the polyglycolic acid composition are greatly improved compared with those of an existing one-step polyglycolic acid preparation technology, and the application requirements in the fields of injection molding, film bags, foaming and the like can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer synthesis, and more particularly to a preparation method, a composition and an application of a polyglycolic acid composition. Background Art

[0002] Polyglycolic acid has excellent mechanical properties, is non-toxic, harmless, green and environmentally friendly, and has effective barrier properties against O2 and CO2. At the same time, polyglycolic acid is also a completely biodegradable material. Its preparation methods mainly include: (1) using glycolic acid (or its derivatives) to directly remove small molecules by polycondensation, which is called a one-step method. Since the polycondensation process is an equilibrium reaction, in order to move the reaction in the direction of molecular chain growth as much as possible, it is necessary to continuously remove the small molecules generated by the reaction. However, as the reaction proceeds, the viscosity of the system becomes higher and higher, and the removal of small molecules becomes more and more difficult. Therefore, the molecular weight of the polyglycolic acid obtained by this method is not high, usually with a weight average molecular weight of less than 20,000, and the melt strength during molding processing is low, and its application is limited; (2) firstly polycondensing glycolic acid (or its derivatives) to obtain a low molecular weight polyglycolic acid prepolymer, and then heating and controlling the decomposition of the prepolymer to obtain a six-membered cyclic glycolide formed by removing small molecules from two molecules of glycolic acid (or its derivatives), and then using the refined glycolide to ring-opening polymerization to obtain polyglycolic acid with a weight average molecular weight greater than 100,000, which is also called a two-step method. The application range of the polyglycolic acid obtained by this method is significantly expanded.

[0003] The current mainstream method is a two-step process to prepare polyglycolic acid, but the two-step process has high requirements for equipment and complex technology, especially the difficulty in obtaining polymerization-grade high-purity glycolide monomer. This has brought great limitations to the expansion of the scale and cost reduction of the polyglycolic acid industry.

[0004] Chinese patent CN111087580 discloses a method for preparing polyglycolic acid. Using glycolic acid as the raw material, a two-step dehydration process yields relatively high molecular weight polyglycolic acid. Compared to the weight-average molecular weight of less than 20,000 obtained through conventional one-step polycondensation of glycolic acid, this method achieves a weight-average molecular weight of approximately 80,000, representing a significant technological advancement. However, this weight-average molecular weight is still relatively low, resulting in insufficient melt strength and toughness, limiting its processing and application areas.

[0005] In summary, the problems existing in the two technical routes for preparing polyglycolic acid in the prior art are as follows: (1) the polyglycolic acid obtained by the one-step route has a low molecular weight, low melt strength during molding, and is difficult to use for subsequent processing; (2) the two-step route is technically complex and has high requirements for equipment, especially the difficulty in obtaining polymerization-grade high-purity glycolide monomer. In this field, how to prepare polyglycolic acid with performance that meets application requirements in a simple, green, and low-cost manner is an urgent problem to be solved. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a method for preparing a polyglycolic acid composition, a composition, and applications thereof. The polyglycolic acid composition provided by the present invention can be prepared simply, environmentally friendly, and cost-effectively by introducing a macroinitiator into the polymerization system. Its overall molecular weight and melt viscosity are significantly improved compared to existing one-step polyglycolic acid preparation technologies, meeting application requirements in injection molding, film bagging, foaming, and other fields.

[0007] One of the objects of the present invention is to provide a method for preparing a polyglycolic acid composition.

[0008] The method for preparing the polyglycolic acid composition of the present invention comprises:

[0009] Step 1) subjecting components including a hydroxy acid monomer, a small molecule initiator, a macromolecular initiator, and a catalyst to atmospheric compression polymerization;

[0010] Step 2) The reaction system of step 1 is further subjected to a reduced pressure polyurethane reaction to obtain the polyglycolic acid composition.

[0011] Preferably,

[0012] The hydroxy acid monomer is at least one of α-hydroxy acid and β-hydroxy acid; preferably, the hydroxy acid monomer is at least one of glycolic acid and lactic acid; more preferably, the hydroxy acid monomer is glycolic acid; and / or,

[0013] The small molecule initiator described in the present invention can be selected from a wide range. In a preferred embodiment of the present invention, the small molecule initiator is a small molecule substance containing hydroxyl and / or amino groups with a boiling point greater than 160°C; and / or,

[0014] The macroinitiator is a polymer containing hydroxyl groups in the repeating unit; preferably at least one of polyvinyl alcohol and ethylene-vinyl alcohol copolymer; and / or,

[0015] The catalyst described in the present invention can be selected from a wide range. In a preferred embodiment of the present invention, the catalyst is at least one of a salt compound of a Group IIA-VA metal element or a transition metal element, or an organic guanidine catalyst. Preferably, the catalyst is a salt compound of at least one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti, and Zn; more preferably, a Sn salt. For example, the catalyst can be selected from stannous octoate, stannous chloride dihydrate, tetra-n-butyl titanate, and the like.

[0016] Preferably,

[0017] The molecular weight of the small molecule initiator is not greater than 1000 g / mol; preferably 60-300 g / mol, including but not limited to 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,

[0018] The alcoholysis degree of the polyvinyl alcohol described in the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the alcoholysis degree of the polyvinyl alcohol is 68-99%. And / or, the polymerization degree of the polyvinyl alcohol described in the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the polymerization degree of the polyvinyl alcohol is 100-6000, preferably 300-2000, for example, 300, 500, 1000, 1500, 2000, and any value within the limited range and the interval between any two values; and / or,

[0019] The ethylene-vinyl alcohol copolymer described in the present invention can be selected from a wide range. In a preferred embodiment of the present invention, the content of ethylene segments in the ethylene-vinyl alcohol copolymer is 0 mol% to 50 mol%, preferably 25-50 mol%, for example, 25 mol%, 35 mol%, 45 mol%, 50 mol%, and any numerical value and any interval within the limited interval; and / or the degree of polymerization of the ethylene-vinyl alcohol copolymer is 50-6000, preferably 300-2000, for example, 300, 500, 1000, 1500, 2000, and any numerical value and any interval within the limited interval; and / or the melt flow rate of the ethylene-vinyl alcohol copolymer described in the present invention can be selected from a wide range. In a preferred embodiment of the present invention, the melt flow rate of the ethylene-vinyl alcohol copolymer at 190°C / 2.16kg is 0.1-50 g / 10min.

[0020] Preferably,

[0021] Based on 100 parts by weight of the hydroxy acid monomer:

[0022] Since the hydroxy acid monomer itself can play the role of a small molecule initiator, a small molecule initiator may not be added. However, in order to better design and control the structure of the final product, a certain amount of a small molecule initiator is usually added. The amount of the small molecule initiator described in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the small molecule initiator is 0-10 parts by weight, preferably 0.001-1 parts by weight, more preferably 0.01-0.5, and most preferably 0.025-0.1 parts by weight.

[0023] The amount of the macroinitiator used in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the macroinitiator used is 0.01-10 parts by weight, preferably 0.1-6 parts by weight, and more preferably 0.5-2 parts by weight.

[0024] Since the catalytic reaction can also be initiated by heat, no catalyst is required. However, in order to increase the reaction efficiency, a certain amount of catalyst is usually added. The amount of the catalyst used in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, the amount of the catalyst is 0-1 part by weight, preferably 0.001-0.5 part by weight, and more preferably 0.01-0.2 part by weight.

[0025] During the preparation of the polyglycolic acid composition of the present invention, an antioxidant may be added. The antioxidant may be selected from a wide range. In a preferred embodiment of the present invention, the antioxidant is selected from hindered phenol antioxidants and / or phosphite antioxidants, that is, it may be hindered phenols and phosphite antioxidants and any combination thereof, including but not limited to 2,6-di-tert-butyl-p-cresol, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), hexanediol bis[β-(3,5-dibutyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (such as BASF's antioxidant Irganox). 1010), N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (such as antioxidant 1024), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (such as antioxidant 1098), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester (such as BASF's antioxidant Irganox 1076), at least one of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, triphenyl phosphite, tris(4-nonphenyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl di(2-ethylhexyl) phosphite, phenyl diisodecyl phosphite, tris(2-ethylhexyl) phosphite, triisodecyl phosphite, tridodecyl phosphite, pentaerythritol diisodecyl diphosphite, tris[2,4-di-tert-butylphenyl] phosphite (such as antioxidant 168), bis(2,4-dicumylphenyl) pentaerythritol diphosphite (such as antioxidant 686) and bis(2,4-di-tert-butylphenyl) propionic acid] pentaerythritol diphosphite (such as antioxidant 626).

[0026] The amount of the antioxidant used in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, based on 100 parts by weight of the hydroxy acid monomer, the amount of the antioxidant is 0-2 parts by weight, preferably 0.01-1 part by weight.

[0027] Preferably,

[0028] The conditions for the atmospheric compression polyurethane reaction described in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, the reaction temperature of the atmospheric compression polyurethane reaction is 110-220° C., and / or the reaction time is 1-24 hours; and / or,

[0029] The conditions for the reduced pressure polyurethane reaction described in the present invention can be selected within a wide range. In a preferred embodiment of the present invention, the reaction temperature of the reduced pressure polyurethane reaction is 160-240°C, and / or the reaction time is 5-100 hours, and / or the vacuum degree is 10-10000 Pa.

[0030] In the present invention, after the normal compression polymerization reaction and the reduced compression polymerization reaction, the molecular weight of the polyglycolic acid can be further increased and the melt index can be further reduced by strengthening means such as solid phase viscosity enhancement.

[0031] The second object of the present invention is to provide a method for preparing a polyglycolic acid composition and the polyglycolic acid composition obtained.

[0032] The polyglycolic acid composition of the present invention comprises a polyester graft copolymer and a polyester homopolymer; the molecular weight distribution thereof is multimodal, comprising a polyester graft copolymer with a higher molecular weight and a polyester homopolymer with a lower molecular weight; wherein the molecular weight of the polyester graft copolymer is higher than that of the polyester homopolymer; the structural formula of the polyester graft copolymer is:

[0033]

[0034] wherein x, y1, y2 and z each independently represent a degree of polymerization, PM represents a polyester chain and the degree of polymerization of the polyester chain is p, wherein x and p each independently represent a positive integer, and y1, y2 and z each independently represent an integer of zero or greater than zero.

[0035] Preferably,

[0036] The polyester graft copolymer and the polyester homopolymer are formed simultaneously in situ; and / or,

[0037] The sum of x, y1, y2 and z is not less than 50, preferably 50-6000, more preferably 200-2500; and / or,

[0038] The p is not less than 33, preferably 35-2000; and / or,

[0039] The ratio of z to the sum of x, y1, y2 and z is 0%-50%; and / or,

[0040] The ratio of y1 to the sum of x, y1 and y2 is 0%-32%.

[0041] Preferably,

[0042] The polyester homopolymer and the polyester chain are independently derived from hydroxy acid monomers; preferably, the polyester homopolymer and the polyester chain are independently derived from at least one of α-hydroxy acid and β-hydroxy acid; more preferably, the polyester homopolymer and the polyester chain are independently derived from at least one of glycolic acid and lactic acid.

[0043] Preferably,

[0044] Based on 100 parts by weight of the total weight of the polyester homopolymer and the polyester chains in the polyester graft copolymer, the copolymer main chain derived from the macroinitiator in the polyester graft copolymer is 0.01-10 parts by weight, preferably 0.1-6 parts by weight, and more preferably 0.5-5 parts by weight; and / or

[0045] Based on the total weight of the polyester graft copolymer and the polyester homopolymer as 100%, the content of the polyester graft copolymer is 0.1wt%-90.0wt%, preferably 1.0wt%-80.0wt%; the content of the polyester homopolymer is 10wt%-99.9wt%, preferably 20.0wt%-99.0wt%.

[0046] Preferably,

[0047] The total weight average molecular weight of the polyglycolic acid composition is 80,000-1.5 million g / mol, preferably 100,000-500,000 g / mol; and / or,

[0048] The polyglycolic acid composition has an overall molecular weight polydispersity index of 1.5-20.0, preferably 2-15; and / or,

[0049] The polyglycolic acid composition has a molecular weight distribution with at least 2 peaks; and / or

[0050] The weight average molecular weight of the polyester graft copolymer is 500,000-10 million g / mol, preferably 800,000-6 million g / mol; and / or,

[0051] The weight average molecular weight of the polyester homopolymer is 5,000-150,000 g / mol, preferably 10,000-100,000 g / mol.

[0052] Preferably,

[0053] The polyester graft copolymer is a polyglycolic acid graft copolymer, and the structural formula of the polyglycolic acid graft copolymer is:

[0054]

[0055] In formula (I), x, y1, y2, z and p each independently represent a degree of polymerization, wherein x and p each independently represent a positive integer, and y1, y2 and z each independently represent an integer of zero or greater.

[0056] Preferably,

[0057] The sum of x, y1, y2 and z is not less than 50, preferably 50-6000, more preferably 200-2500; and / or,

[0058] In the present invention, the selection range of the p value is relatively wide. In a preferred embodiment of the present invention, the p is not less than 33, preferably 35-2000; and / or,

[0059] The ratio of z to the sum of x, y1, y2 and z is 0%-50%; and / or,

[0060] The ratio of y1 to the sum of x, y1 and y2 is 0%-32%.

[0061] Preferably,

[0062] When the main chain of the polyglycolic acid graft copolymer is an ethylene-vinyl alcohol copolymer segment, the ratio of z to the sum of x+y1+y2+z is 1%-50%, preferably 20%-45%, and the ratio of y1 to the sum of x+y1+y2 is 0.1%-6%; and / or,

[0063] When the main chain of the polyglycolic acid graft copolymer is a polyvinyl alcohol segment, z is 0, and the proportion of y1 to the sum of x+y1+y2 is 1%-32%.

[0064] In the present invention, the sum of x+y1+y2+z is the degree of polymerization of polyvinyl alcohol and ethylene-vinyl alcohol copolymer, which can be calculated based on the number average molecular weight of the raw materials polyvinyl alcohol and ethylene-vinyl alcohol copolymer; and the proportion of z in the sum of x+y1+y2+z can be calculated based on the integrated area of the corresponding characteristic peaks of the hydrogen nuclear magnetic spectrum.

[0065] In the present invention, the ratio of x+y2 to the sum of x+y1+y2 (i.e., the ratio of 100% - y1 to the sum of x+y1+y2) is the alcoholysis degree of the ethylene-vinyl alcohol copolymer, which is a known parameter of the raw materials before leaving the factory and can also be detected by various detection methods known in the art such as nuclear magnetic resonance and near infrared.

[0066] According to the present invention, if the structure of the starting ethylene-vinyl alcohol copolymer macroinitiator is known, then p = (number average molecular weight of the high molecular weight PGA fraction - number average molecular weight of the macroinitiator) / (number of vinyl alcohol structures in an ethylene-vinyl alcohol copolymer molecule * molecular weight of the PGA repeating unit). To directly obtain the high molecular weight PGA with the graft copolymer structure described herein, the graft copolymer can be fully hydrolyzed, the initiator collected, and its structure analyzed. Calculations show that the p value for the resulting polymer is greater than 33. The GPC curve of the polyglycolic acid composition of the present invention exhibits a multimodal molecular weight distribution, containing two polyglycolic acid components with different chemical structures: a higher molecular weight polyglycolic acid graft copolymer and a lower molecular weight polyglycolic acid homopolymer.

[0067] Preferably,

[0068] The polyester homopolymer is a polyglycolic acid homopolymer, and the structural formula of the polyglycolic acid homopolymer is:

[0069]

[0070] Where n1, ..., ni are the degrees of polymerization; i is the number of atoms directly connected to R. , i≥1; Mi is an imino group, a secondary amino group or an ether bond; R is at least one of hydrogen, an aliphatic group or an aromatic group; when i>1, M1, M2, ..., Mi are different or the same, and n1, n2, ..., ni are different or the same;

[0071] Preferably, i is any integer from 1 to 20, preferably any integer from 2 to 6, for example, 2, 3, 4, 5, or 6; the selection range of n on each branch is relatively wide, and it is difficult to calculate the respective values. In a preferred embodiment of the present invention, the sum of all n values can be calculated by dividing the number average molecular weight of the lower molecular weight peak in the GPC results by the molecular weight of the PGA repeating unit. After calculation, the sum of all n values is not less than 66; R is an alkane group or an aromatic hydrocarbon group with a molecular weight of 14 to 1000 g / mol.

[0072] In the present invention, the average degree of polymerization (x, y1, y2, z, p and n) obtained by calculation must be rounded off during calculation.

[0073] Preferably,

[0074] The content of each polymer segment in the polyglycolic acid composition of the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the content of each polymer segment in the polyglycolic acid composition is selected in a wide range. For 100 parts by weight ( Present in polyglycolic acid graft copolymer and polyglycolic acid homopolymer middle),

[0075] The polyglycolic acid composition 0.01-10 parts by weight, preferably 0.1-6 parts by weight;

[0076] The polyglycolic acid composition The content of the active ingredient is 0.001-10 parts by weight, preferably 0.01-1 part by weight.

[0077] The weight content of each of the above segments can be determined by methods known in the art, or calculated based on the amount of material added during the preparation process.

[0078] Preferably,

[0079] The total weight average molecular weight of the polyglycolic acid composition of the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the total weight average molecular weight of the polyglycolic acid composition is 80,000-1,500,000 g / mol, preferably 100,000-500,000 g / mol, for example, 100,000 g / mol, 150,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, and any other value or interval within the specified range; and / or,

[0080] The overall molecular weight distribution index of the polyglycolic acid composition of the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the overall molecular weight polydispersity index of the polyglycolic acid composition is 1.5-20.0, preferably 2-15; and / or,

[0081] The polyglycolic acid composition of the present invention has a wide range of selection of the number of molecular weight distribution peaks. In a preferred embodiment of the present invention, the polyglycolic acid composition has at least 2 molecular weight distribution peaks, for example, including but not limited to 2, 3, and / or peak molecular weights M p Greater than 500,000 (i.e., the peak value in the GPC curve lg (M w ) greater than 5.7) and the peak molecular weight M p Less than 500,000 (i.e., the peak value in the GPC curve lg (M w ) is less than 5.7) is at least 1; and / or,

[0082] The number of the molecular weight distribution peaks can be detected by gel permeation chromatography (GPC), and the molecular weight distribution peak can be detected by looking for the peaks at the weight average molecular weight (M w ) is greater than 5000 g / mol (i.e. lg(M w ) is greater than 3.7) and the first derivative is zero and the second derivative is less than zero;

[0083] The weight average molecular weight of the polyglycolic acid graft copolymer described in the present invention can be selected in a wide range. In a preferred embodiment of the present invention, the weight average molecular weight of the polyglycolic acid graft copolymer is 500,000-10 million g / mol, preferably 800,000-6 million g / mol. For example, it can be 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, and any other value and interval within the specified range; and / or,

[0084] The weight-average molecular weight of the polyglycolic acid homopolymer described in the present invention has a wide range of selection. In a preferred embodiment of the present invention, the weight-average molecular weight of the polyglycolic acid homopolymer is 5,000-150,000 g / mol, preferably 10,000-100,000 g / mol. For example, it can be 10,000 g / mol, 20,000 g / mol, 30,000 g / mol, 50,000 g / mol, 80,000 g / mol, 100,000 g / mol, or any other value or interval within the specified range.

[0085] Preferably,

[0086] The content of the polyglycolic acid graft copolymer and the polyglycolic acid homopolymer in the polyglycolic acid composition of the present invention can be selected within a wide range. In a preferred embodiment of the present invention, based on the total weight of the polyglycolic acid composition as 100%, the content of the polyglycolic acid graft copolymer is 0.1 wt%-90.0 wt%, preferably 1.0 wt%-80.0 wt%; the content of the polyglycolic acid homopolymer is 10 wt%-99.9 wt%, preferably 20.0 wt%-99.0 wt%. The proportion of the polyglycolic acid graft copolymer in the whole composition can be calculated from the ratio of the peak area of the portion with a molecular weight greater than 500,000 in the GPC curve to the total peak area; and / or,

[0087] The total weight average molecular weight of the polyglycolic acid composition, the overall molecular weight distribution index of the polyglycolic acid composition, the number of molecular weight distribution peaks of the polyglycolic acid composition, the weight average molecular weight of the polyglycolic acid graft copolymer, the molecular weight polydispersity index of the polyglycolic acid graft copolymer, the molecular weight polydispersity index of the polyglycolic acid homopolymer, the mass fraction of the polyglycolic acid graft copolymer, the mass fraction of the polyglycolic acid homopolymer and other parameters can be detected by gel permeation chromatography (GPC). The specific detection method can adopt conventional detection parameters in the art, for example, but not limited to, the following method is used: the test instrument is a PL-GPC50 gel permeation chromatograph of 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. According to the analytical methods known in the art, the specific values of the above parameters are obtained;

[0088] In a preferred embodiment of the present invention, the melt flow rate (MFR) of the polyglycolic acid composition at 230°C / 2.16kg is 0.5-50 g / 10min, preferably 1-20 g / 10min, for example, 1 g / 10min, 1.5 g / 10min, 2.0 g / 10min, 3.0 g / 10min, 4.0 g / 10min, 5.0 g / 10min, 6.0 g / 10min, 7.0 g / 10min, 8.0 g / 10min, 9.0 g / 10min, 10.0 g / 10min, 12.0 g / 10min, 15.0 g / 10min, 20.0 g / 10min, and any value and any interval within the limited range.

[0089] The melt flow rate can be measured using methods known in the art, such as, but not limited to, the following method: The test is conducted on a CEAST MF20 melt flow tester (Instron, USA). The test temperature is 230°C, the load is 2.16 kg, and the preheating time is 4 minutes.

[0090] A third object of the present invention is to provide a polyglycolic acid composition for use in tableware, lunch boxes, film bags, temporary blocking balls, foaming materials, and barrier materials.

[0091] Compared with the prior art, the present invention has the following advantages:

[0092] The polyglycolic acid composition of the present invention is prepared by a one-step process. The raw material hydroxy acid monomer is more primary, easily available, and has lower cost. The process route is short and the equipment requirements are low. In addition, the polyglycolic acid composition has a high overall molecular weight, a low melt flow rate and high toughness, and can meet the application requirements in the fields of film bags, injection molding, foaming, etc., overcoming the problems of the existing technology and having extremely high promotion and application value.

[0093] The inventors of the present invention believe that the above advantages are due to the following reasons:

[0094] (1) The present invention uses polyhydroxylated polyvinyl alcohol or ethylene-vinyl alcohol copolymer as an initiator to initiate the ring-opening polymerization of the monomers, thereby increasing the hydroxyl content and improving the reaction efficiency. Furthermore, since most of the excess hydroxyl groups are located on the same main chain, the problem of molecular weight reduction caused by excessive initiator in conventional preparation methods is avoided, and an ultra-high molecular weight polyglycolic acid that is difficult to directly obtain using conventional preparation methods can be obtained.

[0095] (2) The presence of the polyglycolic acid homopolymer in the present invention improves the processability of the obtained product, while obtaining a polymer with a wide molecular weight distribution, thereby making it have better mechanical properties.

[0096] (3) The polyglycolic acid composition of the present invention comprises at least two polyglycolic acids of different molecular weights. The high molecular weight portion provides higher melt strength and good mechanical properties, while the low molecular weight portion provides higher toughness and sufficient processing performance. Therefore, the two components of the present invention have a synergistic effect, and obtain comprehensive properties that are difficult for a single-component polyglycolic acid to have.

[0097] (4) Compared with the prior art thickening process using chain extenders such as isocyanates for post-chain extension modification, the polyglycolic acid composition of the present invention is an in-situ synthesized multimodal molecular weight distribution polyglycolic acid material, the preparation process is a one-step process, and the raw materials do not contain highly toxic substances such as isocyanates, thus being more environmentally friendly, efficient, and low-cost. DETAILED DESCRIPTION

[0098] The present invention is described in detail below with reference to the embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0099] 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.

[0100] The raw materials used in the examples and comparative examples of the present invention are all commercially available products, and their specific information is as follows:

[0101] Glycolic acid was purchased from Henan Xingding Chemical Products Co., Ltd. with a purity of 99%.

[0102] Stannous chloride dihydrate, stannous octoate, 1,4-butanediol (BDO, molecular weight 90 g / mol, boiling point approximately 228 °C), glycerol (molecular weight 92 g / mol, boiling point approximately 290 °C), pentaerythritol (molecular weight 136 g / mol, boiling point approximately 380 °C at normal pressure), and tetra-n-butyl titanate were all purchased from Sinopharm Chemical Reagent Co., Ltd., and all were reagent grade.

[0103] Polyvinyl alcohol (PVA) was purchased from Chongqing Chuanwei Chemical Co., Ltd. of Sinopec Group with a brand name of 0388, a degree of polymerization of about 300, a degree of alcoholysis of about 88%, and a number average molecular weight of about 13,200.

[0104] Ethylene-vinyl alcohol copolymer (EVOH) was purchased from Kuraray Co., Ltd., Japan, with the brand name EVAL TM H171B has an ethylene segment content of 38 mol%, a melt flow rate of 1.7 g / 10 min at 190°C / 2.16 kg, and a number average molecular weight of approximately 18,000 g / mol and a degree of polymerization of approximately 480, as determined by GPC. EVOH is typically prepared by alcoholysis of vinyl acetate units in ethylene-vinyl acetate copolymers, with the degree of alcoholysis generally exceeding 99%. Therefore, the number of vinyl acetate units per EVOH molecule used in the present invention (i.e., the value of y1 in formula (I)) is an integer between 0 and 4. For ease of calculation, the value of y1 in the present invention is assumed to be 1.

[0105] The performance of the examples and comparative examples of the present invention was measured according to the following method:

[0106] 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.

[0107] 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.

[0108] [Example 1]

[0109] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of BDO, 12 g of PVA, and 2 g of stannous octoate were added. The mixture was heated to 90°C under normal pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 210°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0110] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M w The molecular weight distribution is 109,000 g / mol, and the molecular weight distribution is 9.8, among which the M w is 9400 g / mol, accounting for about 45%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 788300 g / mol, accounting for about 55%. The result obtained by the melt flow rate determination method described above is 19.2 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 51.

[0111]

[0112] [Example 2]

[0113] To a 5 L reactor, 1200 g of glycolic acid, 2.4 g of BDO, 24 g of PVA, and 2 g of stannous octoate were added. The mixture was heated to 90°C under atmospheric pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which the generated water was distilled off. The temperature was then raised to 220°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 8 hours to produce a polyglycolic acid composition.

[0114] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M wThe molecular weight distribution is 138,000 g / mol, and the molecular weight distribution is 11.3, among which the M w is 8600 g / mol, accounting for about 33%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 543900 g / mol, accounting for about 67%. The result obtained by the melt flow rate determination method described above is 16.5 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 35.

[0115] [Example 3]

[0116] To a 5 L reactor, 1200 g of glycolic acid, 0.6 g of BDO, 12 g of EVOH, and 2 g of stannous octoate were added. The mixture was heated to 90°C under normal pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 220°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0117] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M w The molecular weight distribution is 153,000 g / mol, and the molecular weight distribution is 8.1, among which the M w is 7700 g / mol, accounting for about 47%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 1208700 g / mol, accounting for about 53%. The melt flow rate obtained by the above method is 11.4 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 297, y1 is 1, z is 182, and p is about 69.

[0118] [Example 4]

[0119] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of BDO, 24 g of EVOH, and 2 g of stannous octoate were added. The mixture was heated to 90°C under normal pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 180°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 210°C, and the system pressure was evacuated to 800 Pa. The reaction was continued for 15 hours to produce a polyglycolic acid composition.

[0120] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M wThe molecular weight distribution is 201,000 g / mol, and the molecular weight distribution is 10.2, among which the molecular weight of the low molecular weight part is M w is 5300 g / mol, accounting for about 39%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 893100 g / mol, accounting for about 61%. The result obtained by the melt flow rate determination method described above is 5.6 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 297, y1 is 1, z is 182, and p is about 51.

[0121] [Example 5]

[0122] To a 5 L reactor, 1200 g of glycolic acid, 0.3 g of BDO, 6 g of EVOH, and 2 g of stannous octoate were added. The mixture was heated to 90°C under atmospheric pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which the generated water was distilled off. The temperature was then raised to 220°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 24 hours to produce a polyglycolic acid composition.

[0123] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M w The molecular weight distribution is 117,000 g / mol, and the molecular weight distribution is 9.2, among which the molecular weight of the low molecular weight part is M w is 12000 g / mol, accounting for about 64%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 1598700 g / mol, accounting for about 36%. The result obtained by the melt flow rate determination method described above is 18.3 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 297, y1 is 1, z is 182, and p is about 92.

[0124] [Example 6]

[0125] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of BDO, and 12 g of PVA were added. The mixture was heated to 90°C under atmospheric pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 220°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 48 hours to produce a polyglycolic acid composition.

[0126] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M wThe molecular weight distribution is 95,000 g / mol, and the molecular weight distribution is 12.8, among which the M w is 6600 g / mol, accounting for about 43%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 673200 g / mol, accounting for about 57%. The result obtained by the melt flow rate determination method described above is 17.3 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 43.

[0127] [Example 7]

[0128] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of glycerol, 12 g of PVA, and 2 g of stannous octoate were added. The mixture was heated to 90°C under normal pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The temperature of the system was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which the generated water was distilled off. The temperature was then raised to 210°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0129] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M w The molecular weight distribution is 101,000 g / mol, and the molecular weight distribution is 12.1, among which the M w is 8800 g / mol, accounting for about 44%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 765400 g / mol, accounting for about 56%. The result obtained by the melt flow rate determination method described above is 18.5 g / 10 min. According to the structural formula shown in formula (I), it can be calculated that in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 49.

[0130] [Example 8]

[0131] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of BDO, 12 g of PVA, and 2 g of stannous chloride dihydrate were added. The mixture was heated to 90°C under normal pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which the generated water was distilled off. The temperature was then raised to 210°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0132] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M wThe molecular weight distribution is 92,000 g / mol, and the molecular weight distribution is 10.5, among which the M w is 7800 g / mol, accounting for about 45%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 704200 g / mol, accounting for about 55%. The result obtained by the melt flow rate determination method described above is 19.9 g / 10 min. According to the structure shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 45.

[0133] [Example 9]

[0134] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of pentaerythritol, 12 g of PVA, and 2 g of tetra-n-butyl titanate were added. The mixture was heated to 90°C under atmospheric pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The temperature of the system was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 210°C, and the system was evacuated to a pressure of 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0135] The GPC results obtained according to the above gel permeation chromatography method showed that it had two molecular weight distribution peaks, and the overall M w The molecular weight distribution is 96,000 g / mol, and the molecular weight distribution is 10.5, among which the M w is 8500 g / mol, accounting for about 45%, and the high molecular weight part of M w The melt flow rate of the product of this embodiment is 732100 g / mol, accounting for about 55%. The result obtained by the melt flow rate determination method described above is 18.2 g / 10 min. According to the structural formula shown in formula (I), in the high molecular weight portion of the product of this embodiment, x+y2 is about 264, y1 is about 36, z is 0, and p is about 47.

[0136] [Comparative Example 1]

[0137] To a 5 L reactor, 1200 g of glycolic acid, 1.2 g of BDO, and 2 g of stannous octoate were added. The mixture was heated to 90°C under atmospheric pressure to melt the glycolide. The other materials were thoroughly stirred and mixed. The system temperature was then raised from 90°C to 200°C over 2 hours, and the reaction was continued at this temperature for 2 hours, during which time the generated water was distilled off. The temperature was then raised to 210°C, and the system pressure was evacuated to 1000 Pa. The reaction was continued for 10 hours to produce a polyglycolic acid composition.

[0138] The GPC results obtained by the gel permeation chromatography method showed that there was only one molecular weight distribution peak, M wThe melt flow rate was 8300 g / mol and the molecular weight distribution was 1.9. The melt flow rate was >100 g / 10 min according to the above method.

[0139] A total of 10 pellets from Examples 1-9 and Comparative Example 1 were used in an injection molding feasibility test on an M55 injection molding machine from German company BOY. The injection molding process was as follows: fully dried materials were added to the injection molding machine, melted, injected, and cooled to obtain the target part. The temperatures of sections 1 to 3 and the injection port of the injection molding machine were 200°C, 230°C, 240°C, and 240°C, respectively, and the mold temperature was 60°C. The results showed that during the backward feeding process of the injection screw, the melt viscosity of the pellets from Comparative Example 1 was too low, resulting in a large amount of melt flowing out of the nozzle, making it difficult to complete the entire injection molding process. However, the 9 pellets from Examples 1-9 were able to complete the injection molding process well and obtain the target part.

Claims

1. A method for preparing a polyglycolic acid composition, comprising: Step 1) subjecting components including a hydroxy acid monomer, a small molecule initiator, a macromolecular initiator, and a catalyst to atmospheric compression polymerization; Step 2) The reaction system of step 1 is further subjected to a reduced pressure polyurethane reaction to obtain the polyglycolic acid composition.

2. The preparation method according to claim 1, wherein: The hydroxy acid monomer is at least one of α-hydroxy acid and β-hydroxy acid; preferably, the hydroxy acid monomer is at least one of glycolic acid and lactic acid; more preferably, the hydroxy acid monomer is glycolic acid; and / or, The small molecule initiator is a small molecule substance containing hydroxyl and / or amino groups with a boiling point greater than 160° C.; and / or, The macroinitiator is a polymer containing hydroxyl groups in the repeating unit; preferably at least one of polyvinyl alcohol and ethylene-vinyl alcohol copolymer; and / or, The catalyst is at least one of a salt compound of a metal element of Group IIA-VA or a transition metal element, or an organic guanidine catalyst; preferably a salt compound of at least one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti, and Zn; more preferably a Sn salt.

3. The preparation method according to claim 2, wherein: The molecular weight of the small molecule initiator is not greater than 1000 g / mol; preferably 60-300 g / mol; and / or, The polyvinyl alcohol has an alcoholysis degree of 68-99%, and / or a polymerization degree of 100-6000, preferably 300-2000; and / or, The content of ethylene segments in the ethylene-vinyl alcohol copolymer is 0 mol% to 50 mol%; and / or the degree of polymerization of the ethylene-vinyl alcohol copolymer is 50-6000, preferably 300-2000; and / or the melt flow rate of the ethylene-vinyl alcohol copolymer at 190°C / 2.16kg is 0.1-50g / 10min.

4. The preparation method according to claim 1, wherein: Based on 100 parts by weight of the hydroxy acid monomer: The amount of the small molecule initiator is 0-10 parts by weight, preferably 0.001-1 parts by weight; and / or, The amount of the macroinitiator is 0.01-10 parts by weight, preferably 0.1-6 parts by weight; and / or, The amount of the catalyst used is 0-1 part by weight, preferably 0.001-0.5 part by weight.

5. The preparation method according to claim 1, wherein: The reaction temperature of the atmospheric compression polymerization reaction is 110-220° C., and / or the reaction time is 1-24 hours; and / or, The reaction temperature of the reduced pressure polyurethane reaction is 160-240° C., and / or the reaction time is 5-100 hours, and / or the vacuum degree is 10-10000 Pa.

6. A polyglycolic acid composition prepared by the method according to any one of claims 1 to 5; The polyglycolic acid composition comprises a polyester graft copolymer and a polyester homopolymer; the structural formula of the polyester graft copolymer is: wherein x, y1, y2 and z each independently represent a degree of polymerization, PM represents a polyester chain and the degree of polymerization of the polyester chain is p, wherein x and p each independently represent a positive integer, and y1, y2 and z each independently represent an integer of zero or greater than zero; in, The molecular weight of the polyester graft copolymer is higher than that of the polyester homopolymer.

7. The polyglycolic acid composition according to claim 6, wherein: The sum of x, y1, y2 and z is not less than 50, preferably 50-6000, more preferably 200-2500; and / or, The p is not less than 33, preferably 35-2000; and / or, The ratio of z to the sum of x, y1, y2 and z is 0%-50%; and / or, The ratio of y1 to the sum of x, y1 and y2 is 0%-32%.

8. The polyglycolic acid composition according to claim 6, wherein: The polyester homopolymer and the polyester chain are independently derived from hydroxy acid monomers; preferably, the polyester homopolymer and the polyester chain are independently derived from at least one of α-hydroxy acid and β-hydroxy acid; more preferably, the polyester homopolymer and the polyester chain are independently derived from at least one of glycolic acid and lactic acid.

9. The polyglycolic acid composition according to claim 6, wherein: The polyester graft copolymer is a polyglycolic acid graft copolymer, and the structural formula of the polyglycolic acid graft copolymer is: In the formula, x, y1, y2, z and p each independently represent the degree of polymerization, wherein x and p each independently are positive integers, and y1, y2 and z each independently are integers zero or greater than zero.

10. The polyglycolic acid composition according to claim 9, wherein: The sum of x, y1, y2 and z is not less than 50, preferably 50-6000, more preferably 200-2500; and / or, The p is not less than 33, preferably 35-2000; and / or, The ratio of z to the sum of x, y1, y2 and z is 0%-50%; and / or, The ratio of y1 to the sum of x, y1 and y2 is 0%-32%.

11. The polyglycolic acid composition according to claim 6, wherein: The polyester homopolymer is a polyglycolic acid homopolymer, and the structural formula of the polyglycolic acid homopolymer is: Where n1, ..., ni are the degrees of polymerization; i is the number of atoms directly connected to R. , i≥1; Mi is an imino group, a secondary amino group or an ether bond; R is at least one of hydrogen, an aliphatic group or an aromatic group; when i>1, M1, M2, ..., Mi are different or the same, and n1, n2, ..., ni are different or the same; Preferably, i is any integer from 1 to 20, preferably any integer from 2 to 6; the sum of all n values is not less than 66; and R is an alkane group or an aromatic hydrocarbon group having a molecular weight of 14 to 1000 g / mol.

12. The polyglycolic acid composition according to claim 11, wherein: The polyglycolic acid composition For 100 parts by weight, The polyglycolic acid composition 0.01-10 parts by weight, preferably 0.1-6 parts by weight; The polyglycolic acid composition The content of the active ingredient is 0.001-10 parts by weight, preferably 0.01-1 part by weight.

13. Use of the polyglycolic acid composition prepared by the preparation method according to any one of claims 1 to 5 or the polyglycolic acid composition according to any one of claims 6 to 12 in tableware, lunch boxes, film bags, temporary blocking balls, foam materials, and barrier materials.

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