A method for preparing polyglycolic acid and the obtained polyglycolic acid

Abstract

The present invention discloses a preparation method of polyglycolic acid and the obtained polyglycolic acid, wherein the preparation method comprises: reacting raw materials including glycolide, a catalyst and an acid anhydride additive to obtain polyglycolic acid. The present invention introduces an acid anhydride additive to convert the hydroxyl functional groups in the impurities that affect polymerization into carboxyl functional groups that have little effect on polymerization, thereby reducing the requirements for the purity of glycolide, and obtaining high-viscosity PGA, thereby reducing the cost and further broadening the application range of PGA.

Description

Technical Field

[0001] The invention belongs to the field of polyglycolic acid preparation, and in particular relates to a method for preparing polyglycolic acid and the obtained polyglycolic acid. Background Art

[0002] Polyglycolic acid (PGA) is a type of linear aliphatic polyester. Generally, high molecular weight PGA is prepared from glycolide as raw material, and the molecular weight is adjusted to meet different application requirements. Due to its excellent gas barrier properties, excellent machining performance, and outstanding biodegradability, PGA is widely used in medical materials (surgical sutures and drug sustained-release capsules), packaging materials (bottle linings), membrane materials (ground membranes), and engineering plastics (petroleum fields).

[0003] Polyglycolic acid can be prepared by dehydration polycondensation of glycolic acid, but the molecular weight of the polyglycolic acid prepared by this method is generally not high. In order to prepare high molecular weight polyglycolic acid, the method of glycolide ring-opening polymerization is more often used.

[0004] The preparation of polyglycolic acid requires a lengthy preparation cycle, resulting in high manufacturing costs and limiting its further application. Among them, the purification process of glycolide takes the longest time and consumes a large amount of solvent, which is the key factor in the high cost of polyglycolic acid. This is because the acquisition of polyglycolic acid requires high-purity glycolide raw materials.

[0005] Taking patent CN1703439A as an example, it requires that the water content in the glycolide raw material is below 50 ppm, the α-hydroxycarboxylic acid content is below 100 ppm, and the α-hydroxycarboxylic acid oligomer content is below 1000 ppm.

[0006] Therefore, how to directly polymerize glycolide with high impurity content to obtain high-viscosity polyglycolic acid remains a difficult problem that needs to be solved. Summary of the invention

[0007] In order to overcome the problem in the prior art that high-impurity glycolide cannot be directly polymerized to obtain high-molecular-weight polyglycolic acid, the present invention provides a method for preparing polyglycolic acid, wherein the introduction of anhydride additives during the preparation process can reduce the requirement for the purity of the raw glycolide, thereby obtaining high-molecular-weight polyglycolic acid (PGA), thereby reducing costs and further broadening the application scope of PGA.

[0008] One aspect of the present invention is to provide a method for preparing polyglycolic acid, which is specifically embodied in the following aspects:

[0009] (1) A method for preparing polyglycolic acid, comprising: reacting raw materials including glycolide, a catalyst and anhydride additive to obtain polyglycolic acid.

[0010] (2) The preparation method according to the above (1), wherein the acid value of the glycolide is 1 to 200 mol / t, preferably 2 to 100 mol / t; and / or the water content is 20 to 2000 ppm, preferably 50 to 1000 ppm.

[0011] (3) The preparation method according to the above (1), wherein the catalyst is selected from at least one of stannous octoate, tetraphenyltin, tetrabutyl stannate, stannous chloride, stannic chloride, zinc oxide, diethylzinc, zinc acetate dihydrate, tin lactate, iron lactate, antimony trioxide, and titanium dioxide.

[0012] (4) The preparation method according to the above (1), wherein the amount of the catalyst is 5 to 500 ppm, preferably 10 to 300 ppm, based on the total weight of the raw materials being 100%.

[0013] (5) The preparation method according to the above (1), wherein the acid anhydride additive is selected from at least one of acetic anhydride, propionic anhydride, butyric anhydride, succinic anhydride, maleic anhydride and phthalic anhydride.

[0014] (6) The preparation method according to the above (5), wherein the amount of the acid anhydride additive is 50 to 10000 ppm, preferably 100 to 8000 ppm, based on the total weight of the raw materials being 100%.

[0015] (7) The preparation method according to any one of (1) to (6) above, wherein the reaction is carried out as follows: a preliminary reaction is first carried out, and then the temperature is raised to carry out a post-reaction.

[0016] (8) The preparation method according to (7) above, wherein

[0017] The pre-reaction temperature is 85-180°C and the reaction time is 10 min-10 h; and / or,

[0018] The temperature of the post-reaction is 130-230° C. and the time is 5 min-2 h.

[0019] (9) The preparation method according to (7) above, wherein the pre-reaction and the post-reaction are both carried out in the first reactor; or, the pre-reaction is carried out in the first reactor, and after the pre-reaction is completed, the material is transferred to the second reactor for post-reaction.

[0020] (10) The preparation method according to (9) above, wherein

[0021] The first reactor is selected from at least one of a kettle reactor, a static reactor, and a screw extruder; and / or,

[0022] The second reactor is selected from at least one of a kettle reactor, a static reactor, and a screw extruder.

[0023] The second aspect of the present invention is to provide polyglycolic acid obtained by the preparation method of the first aspect of the present invention, wherein the intrinsic viscosity of the polyglycolic acid is greater than 0.7 dL / g, preferably greater than 0.9 dL / g. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0025] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0026] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0027] One of the purposes of the present invention is to provide a method for preparing polyglycolic acid, comprising: reacting raw materials including glycolide, a catalyst and anhydride additives to obtain polyglycolic acid.

[0028] In a preferred embodiment, the acid value of the glycolide is 1 to 200 mol / t, and the water content is 20 to 2000 ppm.

[0029] In a further preferred embodiment, the acid value of the glycolide is 2-100 mol / t; and the water content is 50-1000 ppm.

[0030] In a preferred embodiment, the catalyst is selected from at least one of stannous octoate, tetraphenyltin, tetrabutyl stannate, stannous chloride, stannic chloride, zinc oxide, diethylzinc, zinc acetate dihydrate, tin lactate, ferric lactate, antimony trioxide, and titanium dioxide.

[0031] In a further preferred embodiment, based on 100% of the total weight of the raw materials, the amount of the catalyst is 5 to 500 ppm, preferably 10 to 300 ppm.

[0032] In a preferred embodiment, the acid anhydride additive is selected from at least one of acetic anhydride, propionic anhydride, butyric anhydride, succinic anhydride, maleic anhydride and phthalic anhydride.

[0033] In a further preferred embodiment, based on 100% of the total weight of the raw materials, the amount of the anhydride additive is 50-10000 ppm, preferably 100-8000 ppm.

[0034] Wherein, the dosage of the acid anhydride additive can be 50ppm, 80ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm or 8000ppm.

[0035] In the prior art, in the preparation of polyglycolic acid, if high molecular weight polyglycolic acid is to be obtained, high purity glycolide is required, and the polyglycolic acid obtained in the prior art contains a large amount of residual glycolide monomers. However, the present invention adds anhydride additives during polymerization to reduce the influence of impurities in glycolide, and the residual monomer content in the polyglycolic acid product is also reduced.

[0036] In a preferred embodiment, the reaction is carried out as follows: a pre-reaction is first carried out, and then the temperature is increased to carry out a post-reaction.

[0037] In a further preferred embodiment, the temperature of the pre-reaction is 85-180° C., and the time is 10 min-10 h.

[0038] For example, the temperature of the pre-reaction can be 85°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, and the time of the pre-reaction can be 10 min, 20 min, 30 min, 40 min, 50 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0039] In a further preferred embodiment, the post-reaction temperature is 130-230° C. and the time is 5 min-2 h.

[0040] For example, the pre-reaction temperature can be 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C or 230°C, and the pre-reaction time can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 1 h, 1.5 h or 2 h.

[0041] In a preferred embodiment, the pre-reaction and the post-reaction are both carried out in the first reactor; alternatively, the pre-reaction is carried out in the first reactor, and after the pre-reaction is completed, the materials are transferred to the second reactor for post-reaction.

[0042] In a further preferred embodiment, the first reactor is selected from at least one of a tank reactor, a static reactor, and a screw extruder; and / or the second reactor is selected from at least one of a tank reactor, a static reactor, and a screw extruder.

[0043] The second object of the present invention is to provide polyglycolic acid obtained by the preparation method described in the first object of the present invention.

[0044] In a preferred embodiment, the intrinsic viscosity of the polyglycolic acid is greater than 0.7 dL / g, preferably greater than 0.9 dL / g.

[0045] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the 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 regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0046] Compared with the prior art, the present invention has the following beneficial effects: In the prior art, high-viscosity polyglycolic acid (PGA) generally requires high-purity glycolide to be obtained through polymerization. Impurities in glycolide, such as glycolic acid dimers, glycolic acid oligomers, residual solvents, water, etc., will affect the polymerization reaction of polyglycolic acid, making it difficult to obtain high-viscosity PGA with application value. At the same time, it is time-consuming and labor-intensive to purify and remove these impurities through glycolide, which greatly increases the cost of raw materials. In response to this phenomenon, the present invention introduces anhydride additives to convert the hydroxyl functional groups in these impurities that affect polymerization into carboxyl functional groups that have little effect on polymerization, thereby reducing the requirements for the purity of glycolide and obtaining high-viscosity PGA. This reduces costs while further broadening the scope of application of PGA.

[0047] [Example and Comparative Example]

[0048] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0049] [Example 1]

[0050] Glycolide with an acid value of 2 mol / t and a water content of 100 ppm, stannous octoate and acetic anhydride were added to a tank reactor for pre-reaction, wherein the amount of stannous octoate was 100 ppm, the amount of acetic anhydride was 100 ppm, the pre-reaction temperature was 90°C, and the reaction time was 2 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 210°C, the reaction time was 8 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.6 dL / g.

[0051] [Example 2]

[0052] Glycolide with an acid value of 10 mol / t and a water content of 50 ppm, tetraphenyltin and propionic anhydride were added to a kettle reactor for pre-reaction, wherein the amount of tetraphenyltin was 10 ppm, the amount of propionic anhydride was 200 ppm, the pre-reaction temperature was 85°C, and the reaction time was 9 hours. After the pre-reaction, the materials were transferred to a static reactor for post-reaction, the reaction temperature was 140°C, the reaction time was 120 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.0 dL / g.

[0053] [Example 3]

[0054] Glycolide with an acid value of 10 mol / t and a water content of 200 ppm, stannous chloride and succinic anhydride were added to a static reactor for pre-reaction, wherein the amount of stannous chloride was 100 ppm, the amount of succinic anhydride was 300 ppm, the pre-reaction temperature was 110°C, and the reaction time was 45 minutes. After the pre-reaction, the materials were transferred to a tank reactor for post-reaction, the reaction temperature was 180°C, the reaction time was 90 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.1 dL / g.

[0055] [Example 4]

[0056] Glycolide with an acid value of 50 mol / t and a water content of 200 ppm, tin chloride and butyric anhydride were added to a static reactor for pre-reaction, wherein the amount of tin chloride was 50 ppm, the amount of butyric anhydride was 2000 ppm, the pre-reaction temperature was 130°C, and the reaction time was 30 minutes. After the pre-reaction, the material was transferred to a screw extruder for post-reaction, the reaction temperature was 220°C, the reaction time was 10 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.3 dL / g.

[0057] [Example 5]

[0058] Glycolide with an acid value of 50 mol / t and a water content of 800 ppm, diethyl zinc and maleic anhydride were added to a kettle reactor for pre-reaction, wherein the amount of diethyl zinc was 300 ppm, the amount of maleic anhydride was 4000 ppm, the pre-reaction temperature was 150°C, and the reaction time was 15 minutes. After the pre-reaction, the material was transferred to a screw extruder for post-reaction, the reaction temperature was 225°C, the reaction time was 15 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.1 dL / g.

[0059] [Example 6]

[0060] Glycolide with an acid value of 70 mol / t and a water content of 900 ppm, tin lactate and phthalic anhydride were added to a screw extruder for pre-reaction, wherein the amount of tin lactate was 200 ppm, the amount of phthalic anhydride was 6000 ppm, the pre-reaction temperature was 170°C, and the reaction time was 10 minutes. After the pre-reaction, the material was transferred to a screw extruder for post-reaction, the reaction temperature was 215°C, the reaction time was 30 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 0.9 dL / g.

[0061] [Example 7]

[0062] Glycolide with an acid value of 70 mol / t and a water content of 200 ppm, titanium dioxide and acetic anhydride were added to a screw extruder for pre-reaction, wherein the amount of titanium dioxide was 100 ppm, the amount of acetic anhydride was 5500 ppm, the pre-reaction temperature was 120°C, and the time was 5 hours. After the pre-reaction, the materials were transferred to a tank reactor for post-reaction, the reaction temperature was 200°C, the time was 60 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.1 dL / g.

[0063] [Example 8]

[0064] Glycolide with an acid value of 90 mol / t and a water content of 100 ppm, iron lactate and propionic anhydride were added to a tank reactor for pre-reaction, wherein the amount of iron lactate was 20 ppm, the amount of propionic anhydride was 8000 ppm, the pre-reaction temperature was 100°C, and the time was 4 hours. After the pre-reaction, the material was transferred to a screw extruder for post-reaction, the reaction temperature was 190°C, the time was 20 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.5 dL / g.

[0065] [Example 9]

[0066] Glycolide with an acid value of 90 mol / t and a water content of 400 ppm, antimony trioxide and butyric anhydride were added to a screw extruder for pre-reaction, wherein the amount of antimony trioxide was 250 ppm, the amount of butyric anhydride was 8000 ppm, the pre-reaction temperature was 110°C, and the reaction time was 7 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 230°C, the reaction time was 6 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.4 dL / g.

[0067] [Comparative Example 1]

[0068] Glycolide with an acid value of 2 mol / t and a water content of 100 ppm and stannous octoate were added to a tank reactor for pre-reaction, wherein the amount of stannous octoate was 100 ppm, the pre-reaction temperature was 90°C, and the reaction time was 2 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 210°C, the reaction time was 8 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.2 dL / g.

[0069] [Comparative Example 2]

[0070] Glycolide with an acid value of 90 mol / t and a water content of 400 ppm and antimony trioxide were added to a screw extruder for pre-reaction, wherein the amount of antimony trioxide was 250 ppm, the pre-reaction temperature was 110°C, and the reaction time was 7 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 230°C, the reaction time was 6 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 0.7 dL / g.

[0071] [Comparative Example 3]

[0072] Glycolide with an acid value of 10 mol / t and a water content of 200 ppm and stannous chloride were added to a static reactor for pre-reaction, wherein the amount of stannous chloride was 100 ppm, the pre-reaction temperature was 110°C, and the reaction time was 45 minutes. After the pre-reaction, the material was transferred to a tank reactor for post-reaction, the reaction temperature was 180°C, the reaction time was 90 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 0.85 dL / g.

[0073] [Comparative Example 4]

[0074] Glycolide with an acid value of 2 mol / t and a water content of 100 ppm, stannous octoate and acetic anhydride were added to a tank reactor for pre-reaction, wherein the amount of stannous octoate was 100 ppm, the amount of acetic anhydride was 50 ppm, the pre-reaction temperature was 90°C, and the reaction time was 2 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 210°C, the reaction time was 8 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 1.3 dL / g.

[0075] [Comparative Example 5]

[0076] Glycolide with an acid value of 2 mol / t and a water content of 100 ppm, stannous octoate and acetic anhydride were added to a kettle reactor for pre-reaction, wherein the amount of stannous octoate was 100 ppm, the amount of acetic anhydride was 10000 ppm, the pre-reaction temperature was 90°C, and the time was 2 hours. After the pre-reaction, the material was transferred to a static reactor for post-reaction, the reaction temperature was 210°C, the time was 8 minutes, and the intrinsic viscosity of the obtained polyglycolic acid resin was 2.0 dL / g, and the viscosity was too high to be suitable for subsequent processing.

[0077] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing polyglycolic acid, comprising: Polyglycolic acid is obtained by reacting raw materials including glycolide, a catalyst and anhydride additives; the reaction is carried out as follows: a pre-reaction is first carried out, and then the temperature is increased for a post-reaction, the pre-reaction temperature is 85-180°C, and the time is 10min-10h; the post-reaction temperature is 130-230°C, and the time is 5min-2h; the glycolide has an acid value of 1-200 mol / t and a water content of 20-2000ppm; the catalyst is selected from stannous octoate, tetraphenyltin, stannic acid At least one of tetrabutyl ester, stannous chloride, tin chloride, zinc oxide, diethyl zinc, zinc acetate dihydrate, tin lactate, ferric lactate, antimony trioxide, and titanium dioxide; based on the total weight of the raw materials being 100%, the amount of the catalyst is 5-500ppm; the anhydride additive is selected from at least one of acetic anhydride, propionic anhydride, butyric anhydride, succinic anhydride, maleic anhydride, and phthalic anhydride; based on the total weight of the raw materials being 100%, the amount of the anhydride additive is 100-8000ppm.

2. The preparation method according to claim 1, characterized in that: The acid value of the glycolide is 2-100 mol / t; and / or the water content is 50-1000 ppm.

3. The preparation method according to claim 1, characterized in that: Based on the total weight of the raw materials being 100%, the amount of the catalyst used is 10-300 ppm.

4. The preparation method according to claim 1, characterized in that: The pre-reaction and the post-reaction are both carried out in the first reactor; alternatively, the pre-reaction is carried out in the first reactor, and after the pre-reaction is completed, the materials are transferred to the second reactor for post-reaction.

5. The preparation method according to claim 4, characterized in that: The first reactor is selected from at least one of a kettle reactor, a static reactor, and a screw extruder; and / or, The second reactor is selected from at least one of a kettle reactor, a static reactor, and a screw extruder.