JP5345483B2 - Polyglycolic acid resin, its production method and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-molecular weight polyglycolic acid-based resin having an amide linkage excellent in heat stability in the molecular chain, a process for producing the same, and its application. <P>SOLUTION: The polyglycolic acid-based resin having a constituting unit represented by formula (1) (wherein R is a polyisocyanate residue and a 1-20C aliphatic hydrocarbon group, a 3-20C hydrocarbon group including an alicyclic structure or a 6-20C hydrocarbon group including an aromatic ring) is obtained by reacting a glycolic acid oligomer having a content of a carboxyl group in the terminal functional group of more than 90% with a polyisocyanate compound. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a polyglycolic acid resin, a production method thereof, and an application thereof.

  With the recent increase in interest in environmental protection, expectations for biodegradable polymers with low environmental impact are also increasing. Polyglycolic acid, one of the biodegradable polymers, has the ability to be decomposed and absorbed in vivo, so research and development and use as medical materials such as surgical sutures have been promoted. ing. In addition, polyglycolic acid is attracting attention as a high-functional general-purpose resin because it is superior in heat resistance and mechanical strength as compared with aliphatic polyesters such as commercially available polylactic acid and has high gas barrier properties. Yes.

  Polyglycolic acid is generally synthesized by (1) ring-opening polymerization of glycolide, which is a cyclic dimer of glycolic acid, (2) dehydration of glycolic acid (aqueous solution) or glycolic acid ester, or dealcoholization polycondensation. Can do. In order to make polyglycolic acid into a molded body such as a film having sufficient mechanical strength, it is necessary to increase the molecular weight, but the method (1) is a monomer, although the high molecular weight body can be synthesized. There was a problem that the yield of glycolide was low, and a large amount of energy was required for purification of glycolide, leading to high cost. In the method of (2), in the case of melt polycondensation as described in Non-Patent Document 1, even if the reaction is carried out while maintaining the molten state, it reaches only a weight average molecular weight of about 50,000. As described in Document 1, it is necessary to raise the polymerization temperature stepwise, and there is a problem that a long time is required.

  As a method for solving the above-described problems, as a method used in polylactic acid and other polyester resins, there is a method of increasing the molecular weight by chain extension reaction using a polyisocyanate compound as disclosed in Patent Document 2. However, there are various problems in adapting to the method of chain extension of polyglycolic acid with a polyisocyanate compound. First, since polyglycolic acid is insoluble in a general general-purpose organic solvent, it is necessary to react at a temperature higher than the melting temperature of the glycolic acid oligomer (240 ° C. or higher). In such a reaction at a high temperature, the bond produced by the chain extension reaction with the polyisocyanate compound needs to be stable at 240 ° C. or higher, and it is necessary to suppress gelation due to side reactions. In general, polyisocyanate compounds can increase the molecular weight by forming a urethane bond by reaction with the hydroxyl group at the end of the polymer, but if the reaction with the hydroxyl group of polyglycolic acid is carried out in the molten state, Since the heat stability of the generated urethane bond is low, there is a problem that it is dissociated and decomposed during the melt reaction or melt molding. Patent Document 3 discloses a method in which a chain extension reaction is performed with a diisocyanate compound in a limited solubilizing solvent such as a hexafluoroisopropanol solvent or a phenol / trichlorophenol mixed solvent. However, since the solubilizing solvent is expensive, it is difficult to say that the solubilizing solvent is economical, and since the generated bond is a urethane bond, thermal decomposition is expected to occur during heat-melt molding.

Japanese Patent Laid-Open No. 11-130647 JP-A-5-148352 JP 2006-152196 A

Polymer 2000, 41, 8725.

  It is an object of the present invention to provide a high molecular weight polyglycolic acid resin that can be produced at low cost and has excellent moldability and thermal stability, a method for producing the same, and a use thereof.

  As a result of diligent studies to solve the above problems, the present inventors have found that a polyglycolic acid resin having an amide bond in a molecular chain obtained through a specific reaction step is excellent in thermal stability and moldability, and The present invention has been found out that it can be manufactured at low cost.

That is, the first invention comprises a glycolic acid oligomer proportion terminal functional group is a carboxyl group is more than 90%, obtained by reacting a di-isocyanate compound compound, a structural unit represented by the following formula (1) A polyglycolic acid-based resin.

In (Equation (1), R is a di-isocyanate residues, carbon atoms containing a hydrocarbon group or an aromatic ring having 3 to 20 carbon atoms include aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic structure Represents 6 to 20 hydrocarbon groups.)

  The polyglycolic acid resin having a weight average molecular weight (Mw2) of the polyglycolic acid resin of 3 times or more of the weight average molecular weight (Mw1) of the glycolic acid oligomer and Mw2 of 90,000 or more is moldable. This is a preferable aspect.

  In differential scanning calorimetry, the melting point (Tm) (second peak of melting peak) of second run when heated at a rate of temperature increase of 10 ° C./min is 200 ° C. ≦ Tm ≦ 220 ° C. and the temperature is raised to 240 ° C. The polyglycolic acid-based resin having a crystallization point (Tc) (peak top of crystallization peak) measured at a temperature decrease rate of 10 ° C./min is 90 ° C. ≦ Tc ≦ 150 ° C. is a preferable embodiment in terms of moldability.

The second invention is a proportion of glycolic acid oligomer than 90% terminal functional group is a carboxyl group, a method of manufacturing the polyglycolic acid resin comprising the step of reacting the presence of the amidation catalyst and di isocyanate compound It is.

  The method for producing a polyglycolic acid resin using an amidation catalyst containing at least one metal selected from the group of metals belonging to Group 1, Group 2 and Group 3 of the Periodic Table facilitates the generation of an amide bond. This is a preferred embodiment.

The method for producing a polyglycolic acid resin using an amidation catalyst containing magnesium or calcium is a preferred embodiment because the formation of an amide bond is facilitated.
The method for producing the polyglycolic acid resin in the molten state of the glycolic acid oligomer is a preferred embodiment in terms of productivity.
A third invention is a molded article containing the polyglycolic acid resin.

  The polyglycolic acid resin of the present invention has an amide bond in the molecular chain, has a practically sufficient high molecular weight, and is excellent in moldability and thermal stability, and is suitable for use in molded articles such as films and sheets. Can be used.

Polyglycolic acid-based resin of the present invention, the terminal functional groups and a glycolic acid oligomer proportion exceeds 90% is a carboxyl group, obtained by reacting a di-isocyanate compound, represented by the following formula (1) Configuration The unit is included.

In the formula (1), R is a di-isocyanate residues, carbon atoms containing a hydrocarbon group or an aromatic ring having 3 to 20 carbon atoms include aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic structure 6 Represents ~ 20 hydrocarbon groups. Specific examples of the aliphatic hydrocarbon group having 1 to 20 carbon atoms include methylene, ethylene, propylene, methylethylene, butylene, 1-methylpropylene, 2-methylpropylene, 1,2-dimethylpropylene, 1,3- Dimethylpropylene, 1-methylbutylene, 2-methylbutylene, 3-methylbutylene, 4-methylbutylene, 2,4-dimethylbutylene, 1,3-dimethylbutylene, pentylene, hexylene, heptylene, octylene, decylene, dodecylene, Examples include ethane-1,1-diyl, propane-2,2-diyl, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, etc., and any —CH ₂ — in the alkyl group is —O—. , -CO-, -COO- or -Si ₂ - may be substituted with. Specific examples of the hydrocarbon group having 3 to 20 carbon atoms including the alicyclic structure include cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,4-cyclohexylene, 1, 5-cyclooctylene, norbornylene, 1,3-cyclopentylene, 1,2-cyclohexylene, 1,4-dimethylcyclohexylene, 1,3-dimethylcyclohexylene, 1-methyl-2,4-cyclohexylene, 4,4'-methylene-biscyclohexylene and 3-methylene-3,5,5-trimethyl-cyclohexylene. Specific examples of the hydrocarbon group having 6 to 20 carbon atoms including the aromatic ring include m-phenylene, p-phenylene, 4,4′-diphenylene, 1,4-naphthalene and 1,5-naphthalene, 4 4,4'-methylenediphenylene, 2,4-tolylene, 2,6-tolylene, m-xylylene, p-xylylene, m-tetramethylxylylene, 4,4'-oxydiphenylene and chlorodiphenylene. . Of these, butylene, pentylene, hexylene, dodecylene, 3-methylene-3,5,5-trimethyl-cyclohexylene, 1,3-dimethylcyclohexylene, and 4,4'-methylene-biscyclohexylene are preferable, hexylene, m- Xylylene is more preferred.

  The structural unit represented by the formula (1) is 4 to 100 units, preferably 4 to 50 units, more preferably 6 to 30 units, and particularly preferably 10 per molecule of the polyglycolic acid resin. Includes ~ 20 units.

  The unit represented by the general formula (1) can be formed by a reaction between a terminal carboxyl group of a glycolic acid oligomer and an isocyanate group. By using an amidation catalyst described later, the carboxyl group can be efficiently converted to an amide. It is also possible to convert it to a group.

The amide bond in the polyglycolic acid resin can be identified by measuring ¹ H-NMR by the method described in Examples described later.
It is also possible to incorporate the copolymer component which reacts with di- isocyanates other than glycolic acid oligomer in the range not impairing the effect of the present invention, such a polyglycolic acid-based resin are also within the scope of the present invention .

[Glycolic acid oligomer with a terminal functional group being a carboxyl group exceeding 90%]
The terminal of the glycolic acid oligomer used in the present invention is a carboxyl group at a ratio exceeding 90%. The terminal carboxyl group ratio is more preferably 95% or more. In the present invention, as described below, to form an amide bond by reaction with the isocyanate group of the terminal carboxyl group and di isocyanate compound of the glycolic acid oligomer. The terminal functional group other than the carboxyl group of the glycolic acid oligomer is usually a hydroxyl group, but the urethane bond produced by the reaction of the hydroxyl group and the isocyanate group is inferior in thermal stability, so the terminal carboxyl group ratio needs to be increased. When the terminal carboxyl group ratio is 90% or less, in order to obtain a high-molecular-weight polyglycolic acid resin having good thermal stability, it is necessary to increase the molecular weight of the glycolic acid oligomer, which is not preferable because the productivity deteriorates.

  As will be described later, when a polyglycolic acid resin is produced by melt polymerization, it is preferable to carry out the polymerization at a temperature higher than the melting point of the glycolic acid oligomer, but the urethane bond is decomposed at a temperature higher than the melting point of the glycolic acid oligomer. Therefore, it is difficult to obtain a high molecular weight polyglycolic acid resin with a polyglycolic acid oligomer having a terminal carboxyl group ratio of 90% or less.

  The glycolic acid oligomer in the present invention contains glycolic acid as a main component. The main component here means that 95 mol% or more of the structural unit is derived from glycolic acid, and includes a copolymer component for making the proportion of the terminal carboxyl group 90% or more at less than 5 mol%, Moreover, as long as the objective of this invention is not impaired, the other copolymerization component unit may be included.

  Examples of the copolymer component unit other than glycolic acid include initiators described later, polycarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids other than glycolic acid, lactones, and the like. Specifically, succinic acid, Polyvalent carboxylic acids such as adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid or their derivatives, ethylene Glycol, propylene glycol, butanediol, hexanediol, octanediol, neopentylglycol, glycerin, trimethylolpropane, aromatic polyhydric alcohol obtained by adding ethylene oxide to bisphenol, diethylene glycol, triethyleneglycol Polyhydric alcohols such as polyethylene glycol and polypropylene glycol or derivatives thereof, hydroxycarboxylic acids such as lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid and 6-hydroxycaproic acid, lactide, ε- Examples include lactones such as caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, and δ-valerolactone.

[Method for producing glycolic acid oligomer in which the terminal functional group is a carboxyl group in excess of 90%]
The glycolic acid oligomer in which the ratio of the terminal functional group as a carboxyl group in the present invention is more than 90% is not particularly limited as long as it does not impair the object of the present invention. It is preferable to synthesize by a direct polycondensation method in which an acid or glycolic acid aqueous solution is directly dehydrated and condensed. For example, the raw glycolic acid or glycolic acid aqueous solution is heated in an inert gas atmosphere or in an air stream, the pressure is lowered to cause a polycondensation reaction, and finally the polycondensation reaction is performed under conditions of a predetermined temperature and pressure. Thus, a glycolic acid oligomer can be obtained. Further, the reaction can be allowed to proceed by solid state polymerization under reduced pressure or under an inert gas stream. In the direct polycondensation method, the proportion of the terminal functional group is a carboxyl group by adding a copolymer component such as polycarboxylic acid or acid anhydride together with glycolic acid, which is a raw material, at either the initial stage, midway or late stage Glycolic acid oligomers can be prepared in excess of 90%. The polycarboxylic acid component is preferably a dicarboxylic acid, and examples of the dicarboxylic acid component include succinic acid, phthalic acid, maleic acid, tetrabromophthalic acid, tetrahydrophthalic acid, dodecyl succinic acid, and the like. To preferred. Examples of the acid anhydride include succinic anhydride, phthalic anhydride, maleic anhydride, tetrabromophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride or dodecyl succinic anhydride, and succinic anhydride is preferable from the viewpoint of cost. . The addition amount when the polycarboxylic acid or acid anhydride is added in the latter stage of polymerization is preferably 1-fold mole relative to the number of moles of terminal hydroxyl groups of the glycolic acid oligomer before addition. Here, “fold mole” is a unit of a value calculated by “number of moles of polycarboxylic acid or acid anhydride / number of moles of hydroxyl group terminal”. The number of moles of the hydroxyl group terminal can be determined by measuring ¹ H-NMR with the amount used and the method described in the examples described later. When the polycarboxylic acid or acid anhydride is added at the start of polymerization or in the middle thereof, the addition amount is adjusted so that the glycolic acid oligomer described later has a target molecular weight. For example, as a specific example of adding succinic acid, when the number average molecular weight of the glycolic acid oligomer is 2500, the reaction may be performed so that the molar ratio of glycolic acid: succinic acid is 41: 1.
When adding at the start of polymerization or in the middle, usually 0.4 to 5 mol%, more preferably 0.5 to 3 mol% is used relative to the charged glycolic acid.

The polycondensation reaction may be performed without a catalyst or in the presence of a conventionally used polycondensation catalyst. The preparation time of the glycolic acid oligomer can be shortened by using a catalyst. Metals and metal salts as metal-based polycondensation catalyst conventionally used, a metal oxide, and the like, since the removal of metallic catalyst from the glycolic acid oligomer is difficult, and di isocyanate compound described later It is necessary to select a catalyst that does not inhibit this reaction. Examples of such metal catalysts include magnesium, calcium, and salts and oxides thereof. Moreover, the organic sulfonic acid type catalyst conventionally used as a polycondensation catalyst can be used. Examples of the organic sulfonic acid catalyst include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid and the like. Preferable examples include methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. When solid-phase polymerization is performed using an organic sulfonic acid-based catalyst, the reaction temperature is raised as the reaction proceeds, so that it is possible to eventually volatilize the catalyst and reduce the residual catalyst as much as possible. it can. When using a catalyst, the addition amount is 0.001-1 weight part with respect to 100 weight part of glycolic acid, Preferably it is 0.002-0.5 weight part.
In the method of ring-opening polymerization of glycoside, it can be adjusted using water or an initiator such as hydroxycarboxylic acid such as lactic acid or glycolic acid.

[Weight average molecular weight of glycolic acid oligomer <Mw1>]
The glycolic acid oligomer has a weight average molecular weight (Mw1) of preferably 5,000 to 50,000, particularly preferably 10,000 to 30,000. When the weight average molecular weight (Mw1) is within the above range, it is preferable in that the polymerization time is short and the process time can be shortened. Moreover, by making it into the said molecular weight range, the melting temperature of polyglycolic acid-type resin can be lowered | hung and the polyglycolic acid-type resin excellent in heat workability can be obtained.

  In addition, the weight average molecular weight (Mw) in this invention is a relative weight average molecular weight with respect to polymethyl methacrylate by the gel permeation chromatography (henceforth GPC) which used the hexafluoro isopropanol as a mobile phase by the method as described in the Example mentioned later. As measured.

[Method for producing polyglycolic acid resin]
Method for producing a polyglycolic acid resin comprises glycolic acid oligomer proportion terminal functional group is a carboxyl group exceeds 90%, the step of reacting a di- isocyanate compound. In the reaction, it is preferable to use an amidation catalyst described later. Although the following melt polymerization methods are mentioned as a specific example of this process, As long as the objective of this invention is not impaired, it is not limited to this at all.

First, the glycolic acid oligomer and, if necessary, an amidation catalyst described later are added, and these are heated to a temperature at which the glycolic acid oligomer melts. Furthermore the di-isocyanate compound is added, it is possible to obtain a polyglycolic acid-based resin is reacted at the melting temperature. Di isocyanate compound is preferably a diisocyanate compound.

  Although it is possible to use a solvent such as dimethyl sulfoxide, the above-described melt polymerization method is a preferred embodiment because post-treatment such as solvent removal is required.

[Reaction temperature]
The reaction temperature in the melt polymerization method is preferably equal to or higher than the melting temperature of the glycolic acid oligomer, and is preferably 230 ° C to 250 ° C. If the reaction temperature in the step exceeds the upper limit, side reactions may proceed and gelation may occur easily. If the reaction temperature is lower than the lower limit, the glycolic acid oligomer does not dissolve, and the polyglycolic acid resin in the present invention It may not be obtained. In the melt polymerization method, the viscosity rapidly increases with the increase in the molecular weight of the reaction product. Therefore, a method of extruding the product while reacting with an extruder, particularly a twin-screw kneading extruder is a preferred embodiment.

[Di isocyanate compound]
Di isocyanate compound used in the present invention are compounds that are two chromatic isocyanate group is not particularly limited unless impair the object of the present invention.

  As the diisocyanate compound, 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 1,3- (bisisocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, bis (Isocyanatomethyl) bicyclo- [2,2,1] -heptane or bis (4-isocyanatocyclohexyl) methane and the like, more preferred examples m-xylylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 1,3- (bisisocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, bis (Isocyanatomethyl) bicyclo- [2,2,1] -heptane, bis (4-isocyanatocyclohexyl) methane, and the like can be given. Of these, hexamethylene diisocyanate or m-xylylene diisocyanate is preferable from an economical viewpoint.

[Added in an amount of di-isocyanate]
The addition amount of the di-isocyanate compound is determined based on the number of moles calculated from the carboxyl group terminal number of the glycolic acid oligomer. The number of carboxyl group terminals of the glycolic acid oligomer is calculated from ¹ H-NMR. ¹ H-NMR is measured by the method described in Examples described later. The addition amount of the di-isocyanate compound is preferably 0.8 to 2.0 times by mole based on the mole number calculated from the carboxyl group terminal number of the glycolic acid oligomer, 0.8 to 1.5-fold molar More preferably. Here, the "fold molar" is a unit of a value calculated by the "number of moles / terminal carboxyl group of the isocyanate groups in the di-isocyanate compound".

If the amount of the di-isocyanate compound is less than the above lower limit, the effect of adding the di-isocyanate compound is small, it is difficult to obtain a high molecular weight polyglycolic acid resin. On the other hand, when the above upper limit is exceeded, the isocyanate may cause a side reaction such as a crosslinking reaction, and a gel-like polyglycolic acid resin may be generated.

[Amidation catalyst]
The amidation catalysts in the present invention, a terminal carboxyl group portion of the glycolic acid oligomer is reacted preferentially with the di isocyanate compound, it refers to a catalyst to form an amide bond.

  The amidation catalyst used in the step preferably contains at least one metal selected from the group of metals in Groups 1, 2 and 3 of the periodic table, and is selected from the group of potassium, magnesium, calcium and ytterbium. More preferably, it contains at least one metal, and particularly preferably contains magnesium or calcium. The inclusion of such a metal is preferable in terms of catalytic effect.

  Examples of the amidation catalyst containing Group 1 metal of the periodic table include organic metal compounds such as organic acid salts, metal alkoxides or metal complexes (acetylacetonate, etc.) of lithium, sodium, potassium, rubidium or cesium; Inorganic metal compounds such as compounds, metal hydroxides, carbonates, phosphates, sulfates, nitrates, chlorides or fluorides, and as amidation catalysts containing Group 2 metals of the above periodic table, Organometallic compounds such as organic acid salts, metal alkoxides or metal complexes (such as acetylacetonate) of beryllium, magnesium, calcium, strontium or barium; metal oxides, metal hydroxides, carbonates, phosphates, sulfates Inorganic metal compounds such as nitrates, chlorides and fluorides. Furthermore, as the amidation catalyst containing the Group 3 metal of the periodic table, organometallic compounds such as scandium, ytterbium, yttrium or other rare earth organic acid salts, metal alkoxides or metal complexes (acetylacetonate, etc.) Inorganic metal compounds such as metal oxides, metal hydroxides, carbonates, phosphates, sulfates, nitrates, chlorides or fluorides; These may be used alone or in combination. Among these metal compound catalysts, bis (acetylacetonato) magnesium, magnesium stearate, calcium stearate, magnesium chloride, ytterbium triflate, etc. are preferable, and magnesium compounds, particularly bis (acetylacetonato) magnesium, magnesium stearate. Is preferred. Two or more of these catalysts can be used in combination.

[Amount of addition of amidation catalyst]
The amount of the amidation catalyst added is 0.01 to 2 parts by weight, preferably 0.01 to 1 part by weight, more preferably 0.01 to 0.5 parts by weight, based on 100 parts by weight of the glycolic acid oligomer. It is.

[Weight average molecular weight of polyglycolic acid resin <Mw2>]
The weight average molecular weight (Mw2) of the polyglycolic acid resin in the present invention is preferably 90,000 or more, more preferably 90,000 to 500,000, and 120,000 to 300,000. Is more preferable. It is preferable in terms of moldability and mechanical strength that the weight average molecular weight (Mw2) of the polyglycolic acid resin is within the above range.

The weight average molecular weight of the polyglycolic acid resin in the present invention (Mw2) has a weight average molecular weight of the glycolic acid oligomer by reaction with di isocyanate (Mw1) of 3 times or more, more preferably 3 to 51 times, particularly preferably It is preferably 3 to 26 times. If it is 3 times or less, the thermal characteristics of the polyglycolic acid resin in the present invention described later may not be exhibited.

[Thermal properties of polyglycolic acid resins]
The polyglycolic acid-based resin of the present invention has a feature that the melting point is lower than the melting point (about 240 ° C.) of a conventional general polyglycolic acid homopolymer. When a conventional polyglycolic acid homopolymer is melted at a temperature higher than the melting point at the time of melt molding, thermal decomposition or the like occurs and there is a problem in processing stability. Since the melting temperature is lower than that of glycolic acid homopolymer, molding processing can be performed while suppressing a decrease in molecular weight due to thermal decomposition.

  That is, the polyglycolic acid resin of the present invention has a melting point (Tm) (second peak of melting peak) of second run when heated at a temperature rising rate of 10 ° C./min in a differential scanning calorimetry method described later at 190 ° C. ≦ Tm ≦ 230 ° C., preferably 200 ° C. ≦ Tm ≦ 220 ° C.

  Tm can be lowered by decreasing Mw1 of the glycolic acid oligomer within the above range, and can be increased by increasing Mw1, and Tm can be increased by controlling Mw1 of the oligomer. Can be adjusted to the range.

  In addition, polyglycolic acid homopolymer has a very high crystallization rate when the temperature is lowered from a molten state, that is, it has a high crystallization point and is difficult to control crystallization, and is transparent during extrusion molding of films, sheets, etc. There was a problem of impairing the performance. In order to lower the crystallization point, it is necessary to perform heat treatment at a high temperature as disclosed in, for example, Patent Document (WO2003-037956). The polyglycolic acid resin in the present invention has a crystallization point (Tc) (peak top of crystallization peak) of 90 measured at a temperature decrease rate of 10 ° C./min after receiving a thermal history of 240 ° C. in differential scanning calorimetry. Since the temperature can be set to ≦ Tc ≦ 150 ° C., further 110 ° C. ≦ Tc ≦ 140 ° C., the temperature difference between the melting temperature and the crystallization point can be increased, and the crystallization can be easily controlled. .

Crystallization point Tc, depending on the type of the di-isocyanate compound used, the Mw1 generally the glycolic acid oligomer is capable of low to be smaller within the range, increasing the Mw1 The Tc can be adjusted to the above range by controlling the oligomer Mw1.

[Molded body of polyglycolic acid resin and molding process and application]
The polyglycolic acid-based resin of the present invention can be molded by various molding processes, but as described above, it is excellent in melt processability. The molded product as used herein means various molded products such as films, sheets, fibers, injection molded products, extruded molded products, vacuum molded products, and foam molded products.

  The molding method is not particularly limited, and specific examples include injection molding, extrusion molding, inflation molding, extrusion hollow molding, foam molding, calendar molding, blow molding, balloon molding, vacuum molding, spinning, and the like. It is done.

  There is no restriction | limiting in particular about the use of the polyglycolic acid-type resin of this invention, It can be used in a wide range from general use to special uses, such as a medical device. In particular, the high gas barrier property characteristic of polyglycolic acid is equivalent to the polyglycolic acid homopolymer in the polyglycolic acid-based resin of the present invention, as described in Examples below. It is desirable to use for applications that require gas barrier properties. It can also be used in the suture field where conventional polyglycolic acid resins are widely used.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to these Examples at all.
Each measurement method in this example is shown below.

<Weight average molecular weight (Mw)>
Gel permeation chromatography (GPC, Waters, detector RI: Waters 2414, column: SHODEX HFIP-G, HFIP-806 2) (detector and column temperature 40 ° C., flow rate 0.6 mL / Min, 5 mM sodium trifluoroacetate (Wako Pure Chemicals) -containing hexafluoroisopropanol (manufactured by Central Glass Co., Ltd.), polymethyl methacrylate (molecular weights 520000, 267000, 158000, 93300, 54500, 10100, 2580, respectively) as standard It was obtained by comparison with a calibration curve prepared as a sample. The sample was dissolved in 5 mL of 5 mM sodium trifluoroacetate (Wako Pure Chemical Industries) containing hexafluoroisopropanol (manufactured by Central Glass Co., Ltd.) and measured.

<Measuring method of glass transition temperature (Tg), melting point (Tm), crystallization point (Tc), crystallinity>
It calculated | required by the scanning scanning calorimetry (DSC measurement) (DSC apparatus RDC220 by SII). A sample is weighed 5 to 6 mg, weighed into a nitrogen-sealed pan, charged in a DSC measuring section set at 30 ° C. that has been nitrogen-sealed in advance, and then heated to 240 ° C. at a rate of 10 ° C./min. did. Thereafter, the temperature was decreased to 0 ° C. at a temperature decreasing rate of 10 ° C./min. Furthermore, it heated up to 240 degreeC with the temperature increase rate of 10 degree-C / min.
As the glass transition temperature (Tg), the glass transition temperature at the second temperature increase (second run) was measured.

Melting point (Tm), crystallinity was measured by measuring peak melting point (Tm) and crystal melting enthalpy (ΔHm) at the melting exothermic peak at the second temperature rise, and [[(ΔHm) / (ΔH ₀ )] × 100] was determined as the crystallinity. Here, ΔH ₀ represents the complete ideal crystal melting enthalpy, and the value of polyglycolic acid 183.2 J / g (Polymer 2004, 45, 3583.) was used.

  As the crystallization point (Tc), the crystallization point (Tc) at the peak top of the crystallization exothermic peak when the temperature was lowered and cooled at a temperature lowering rate of 240 ° C. to 10 ° C./min was measured.

<Measurement method of ratio of terminal functional group of polyglycolic acid oligomer being carboxyl group>
ECA500 manufactured by JEOL Ltd. was used to measure ¹ H-NMR spectrum of glycolic acid oligomer and polyglycolic acid resin in a heavy dimethyl sulfoxide solvent at 100 ° C. Here, the chemical shift was based on dimethyl sulfoxide δ = 2.468 ppm.

  When the sample was difficult to dissolve, the sample was melted once in an inert gas atmosphere and then rapidly cooled to prepare a measurement sample.

In the ¹ H-NMR spectrum of the polyglycolic acid oligomer obtained by the above measurement,
δ = 4.10 ppm, singlet (integral value A):
Methylene proton at the hydroxyl group end of glycolic acid oligomer δ = 4.61 ppm, singlet (integral value B):
Methylene proton at the carboxyl group end of the glycolic acid oligomer δ = 4.74, −4.83 ppm, singlet (integral value C):
Glycolic acid oligomer main chain methylene proton, for example, glycolic acid oligomer prepared by initial addition of succinic anhydride,
δ = 2.70 ppm, singlet (integral value D):
Methylene proton succinate can be identified as described above.
From the integrated value of these peaks, the terminal carboxylic acid ratio is calculated from the following formula.
Ratio (%) where terminal functional group is carboxyl group = B / (A + B) × 100

<Mole number of carboxyl group terminal of glycolic acid oligomer (mol / g)>
Based on the spectrum obtained by the above measuring method, the number of moles (mol / g) of ruboxyl terminal is calculated by the following formula.
Carboxyl group terminal mole number (mol / g)
= B / (59 (OH terminal glycolic acid unit) x A + 75 (COOH terminal glycolic acid unit) x B + 58 (main chain glycolic acid unit) x C + 100 (acid anhydride or polycarboxylic acid unit (here succinic acid unit)) x D / 2)

<Identification of amide bond in polyglycolic acid resin>
For example using a glycolic acid oligomer succinic anhydride was prepared by initial addition, as an example polyglycolic acid-based resin obtained using hexamethylene diisocyanate as di-isocyanate, to identify the amide bond formation by ¹ H-NMR spectrum The method is described below. ¹ H-NMR measurement is performed in the same manner as the glycolic acid oligomer.
δ = 1.2-1.31 ppm, broad:
Methylene protons derived from hexamethylene diisocyanate δ = 1.35-1.45 ppm, broad:
Methylene protons derived from hexamethylene diisocyanate δ = 1.35-1.45 ppm, broad:
Amide bond adjacent α-position methylene proton derived from hexamethylene diisocyanate δ = 2.70 ppm, singlet:
Methylene proton derived from succinic acid δ = 4.10 ppm, singlet:
Methylene proton at the hydroxyl group terminal of the glycolic acid unit δ = 4.51 ppm, singlet:
Methylene proton at the α-position adjacent to the amide bond of the glycolic acid unit δ = 4.77 ppm, singlet:
Methylene proton at the β position adjacent to the amide bond of the glycolic acid unit δ = 4.83 ppm, singlet:
Methylene proton of polymer main chain glycolic acid unit δ = 7.60 ppm, broad:
Amide protons can be identified as above.

Here, the chemical shift of the hydroxyl group terminal methylene proton is the same as the hydroxyl group terminal methylene proton of the glycolic acid oligomer used, and the chemical shift of the carboxyl group terminal of the glycolic acid oligomer forms an amide bond to form a high magnetic field. A shift can be confirmed (δ = 4.61 ppm → δ = 4.51 ppm). Proton amide bond is chemical shift changes by di isocyanate species employed, but can be identified around δ = 7.5-8.5ppm.

<Oxygen transmission coefficient>
About oxygen permeability of press film of 150μm thickness of polyglycolic acid resin, oxygen permeability coefficient was measured under conditions of 23 ° C and 80% RH using OXTRAN equipment manufactured by MOCON according to JIS K-7126. It was measured.

[Production Example 1]
380 g (5.0 mol) of glycolic acid (Glypure 99) manufactured by DuPont and 12.17 g (0.1217 mol) of succinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), 1000 ml of Separa equipped with a Dean-Stark trap and a nitrogen introduction tube A bull flask was charged. After the atmosphere in the flask was replaced with nitrogen, the glycolic acid was dissolved by heating with an oil bath heated to 140 ° C. under a nitrogen flow of normal pressure and 30 L / min. The inside of the flask was gradually depressurized and maintained at 100 mmHg for 3 hours until the reaction mass became cloudy. Next, the oil bath temperature was raised to 180 ° C., and the reaction was continued for further 3 hours until it solidified. The obtained white solid was pulverized by a pulverizer and dried at 180 ° C. for 12 hours under a nitrogen stream to obtain 288 g of a white glycolic acid oligomer [oligomer A]. The weight average molecular weight (Mw1) of the oligomer A measured by GPC was 17600. Moreover, terminal functional groups which is calculated by ¹ H-NMR measurement ratio is a carboxyl group is 96%, the carboxyl group-terminated moles was ^{7.1065 × 10 -4 (mol / g} ). According to DSC measurement, the Tg was 29.6 ° C, the Tm was 209 ° C, and the crystallinity was 64%.

[Production Example 2]
1000 ml Separa equipped with a Dean-Stark trap and a nitrogen introduction tube containing 380 g (5.0 mol) of glycolic acid (Glypure 99) manufactured by DuPont and 5.94 g (0.0594 mol) of succinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) A bull flask was charged. After the atmosphere in the flask was replaced with nitrogen, the glycolic acid was dissolved by heating with an oil bath heated to 140 ° C. under a nitrogen flow of normal pressure and 30 L / min. The inside of the flask was gradually depressurized and maintained at 100 mmHg for 2.5 hours until the reaction mass became cloudy. Next, the oil bath temperature was raised to 180 ° C., and the reaction was continued until solidified for another hour. The obtained white solid was pulverized by a pulverizer and dried at 180 ° C. for 12 hours under a nitrogen stream to obtain 275 g of a white glycolic acid oligomer [oligomer B]. The weight average molecular weight (Mw1) of the oligomer B measured by GPC was 30000. Moreover, terminal functional groups which is calculated by ¹ H-NMR measurement ratio is a carboxyl group is 92%, the carboxyl group-terminated mole number was ^{4.726 × 10 -4 (mol / g} ). According to DSC measurement, Tg could not be observed, Tm was 219 ° C. and crystallinity was 52%.

[Production Example 3]
380 g (5.0 mol) of glycolic acid (Glypure 99) manufactured by DuPont was charged into a 1000 ml separable flask equipped with a Dean-Stark trap and a nitrogen inlet tube. After the atmosphere in the flask was replaced with nitrogen, the glycolic acid was dissolved by heating with an oil bath heated to 140 ° C. under a nitrogen flow of normal pressure and 30 L / min. The inside of the flask was gradually depressurized and maintained at 100 mmHg for 2.0 hours until the reaction mass became cloudy. Next, the oil bath temperature was raised to 180 ° C., and the reaction was continued until solidified for another hour. The obtained white solid was pulverized by a pulverizer to obtain 285 g of a white glycolic acid oligomer [oligomer C]. The oligomer C had a weight average molecular weight (Mw1) of 15000 as measured by GPC. Moreover, terminal functional groups which is calculated by ¹ H-NMR measurement ratio is a carboxyl group is 50%, the carboxyl group-terminated moles was ^{2.1739 × 10 -4 (mol / g} ). By DSC measurement, Tg could not be observed, Tm was 210 ° C. and crystallinity was 58%.

[Production Example 4]
380 g (5.0 mol) of glycolic acid (Glypure 99) manufactured by DuPont and 2.97 g (0.0297 mol) of succinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), 1000 ml of Separa equipped with a Dean-Stark trap and a nitrogen introduction tube A bull flask was charged. After the atmosphere in the flask was replaced with nitrogen, the glycolic acid was dissolved by heating with an oil bath heated to 140 ° C. under a nitrogen flow of normal pressure and 30 L / min. The inside of the flask was gradually depressurized and maintained at 100 mmHg for 3 hours until the reaction mass became cloudy. Next, the oil bath temperature was raised to 180 ° C., and the reaction was continued until solidified for another hour. The obtained white solid was dried at 180 ° C. for 1 hour under a nitrogen stream to obtain 288 g of a white glycolic acid oligomer [oligomer D]. The oligomer D had a weight average molecular weight (Mw1) of 23,300 as measured by GPC. Moreover, terminal functional groups which is calculated by ¹ H-NMR measurement ratio is a carboxyl group is 82%, the carboxyl group-terminated mole number was ^{4.56 × 10 -4 (mol / g} ). According to DSC measurement, Tg was 32 ° C., Tm 217 ° C., and the crystallinity was 50%.

[Example 1]
30 g of oligomer A synthesized in Production Example 1 (0.0213 mol as a carboxyl group) and 22 mg (0.0372 mmol) of magnesium stearate were charged into a 100 ml glass flask with a side tube equipped with a stirring rod. The interior of the flask was purged with nitrogen three times, and the temperature was raised to 240 ° C. in a nitrogen atmosphere to dissolve the oligomer. Next, 2.54 g of hexamethylene diisocyanate (0.0151) was added to the flask. mol, 1.42 moles of isocyanate group with respect to the terminal carboxyl group) and reacted for a total of 25 minutes, and then taken out on a Teflon (registered trademark) sheet to obtain a polyglycolic acid resin. With respect to the resin, the weight average molecular weight (Mw2) was measured by the above measurement method. As a result, it was 142000, and the weight average molecular weight increased to 8 times. ¹ H-NMR was measured by the above measurement method, and amide bond formation was confirmed. Various other thermal characteristic data are shown in Table 1.

  Further, about 4 g of the resin was sandwiched between polyimide films (trade name: Upilex (manufactured by Ube Industries)), inserted into a vacuum hot press machine heated to 250 ° C., depressurized over 5 minutes, and then vacuum hot pressed at 3 MPa for 20 seconds. . After quenching, the obtained film was peeled from the polyimide film to obtain a transparent film having a thickness of 150 μm. The results of measuring the oxygen permeability coefficient of the press film by the above measuring method are also shown in Table 1.

[Example 2]
A polyglycolic acid-based resin was obtained in the same manner as in Example 1 except that hexamethylene diisocyanate was changed to m-xylylene diisocyanate (isocyanate group was 1.30 times mol relative to the terminal carboxyl group). With respect to the resin, the weight average molecular weight (Mw2) was measured by the above measurement method. As a result, it was 188000, and the weight average molecular weight increased to about 11 times. ¹ H-NMR was measured by the above measurement method, and amide bond formation was confirmed. Assignments different from those in Example 1 are shown below.
δ = 4.30 ppm, doublet: benzylic proton δ = 4.60 ppm, singlet: methylene proton adjacent to amide bond of glycolic acid unit δ = 7.12-7.28 ppm, multiplet: benzene ring proton δ = 8 .20 ppm, broad: amide proton Other various thermal characteristics data are shown in Table 1.
Moreover, the press film was created similarly to Example 1 and the transparent film was obtained. The results of measuring the oxygen permeability coefficient of the press film by the above measuring method are also shown in Table 1.

[Example 3]
The oligomer A was changed to the oligomer B synthesized in Production Example 2, and m-xylylene diisocyanate was used in the same manner as in Example 2 except that the isocyanate group was used in an amount of 1.24 moles with respect to the terminal carboxyl group. A polyglycolic acid resin was obtained. With respect to the resin, the weight average molecular weight (Mw2) was measured by the above measurement method. As a result, it was 196,000, and the weight average molecular weight was increased to about 6.5 times. ¹ H-NMR was measured by the above measurement method, and amide bond formation was confirmed. Various other thermal characteristic data are shown in Table 1.

[Comparative Example 1]
The reaction was performed in the same manner as in Example 1 except that the oligomer A was changed to the oligomer C synthesized in Production Example 3. About this resin, when the weight average molecular weight (Mw2) was measured by the said measuring method, it was 18000 and the weight average molecular weight hardly increased.
Moreover, although the press film was created similarly to Example 1, it did not become a film.

[Comparative Example 2]
The reaction was carried out in the same manner as in Example 1 except that the oligomer A was changed to the oligomer C synthesized in Production Example 3, and hexamethylene diisocyanate was used so that the isocyanate group was 2.40 times moles relative to the terminal carboxyl group. went. About this resin, when the weight average molecular weight (Mw2) was measured by the said measuring method, it was 25500 and the weight average molecular weight hardly increased.
Moreover, although the press film was created similarly to Example 1, it did not become a film.

[Comparative Example 3]
The reaction was carried out in the same manner as in Example 1 except that the oligomer A was changed to the oligomer D synthesized in Production Example 4 and hexamethylene diisocyanate was further used so that the isocyanate group was 1.32 moles relative to the terminal carboxyl group. went. With respect to the resin, the weight average molecular weight (Mw2) was measured by the above measurement method. As a result, it was 68000, and the weight average molecular weight increased only to 2.9 times.
Moreover, although the press film was created similarly to Example 1, it did not become a strong film.

[Reference example]
After charging 116 g (1.0 mol) of glycolide (manufactured by Pulac) into a 200 mL glass reactor equipped with a stirrer, nitrogen substitution was performed three times. Under a nitrogen atmosphere, 5 mL of a toluene solution of tin octoate (1.0 M) and 220 mg (2.3 mmol) of glycolic acid were added, and then toluene was distilled off under reduced pressure. The mixture was heated and stirred at 200 ° C. for 3 hours, and a solidified white product was taken out. The product was pulverized and then dried at 180 ° C. for 3 hours under a nitrogen stream to obtain polyglycolic acid by ring-opening polymerization of glycolide.

  Table 1 shows analytical values of polyglycolic acid homopolymers synthesized by ring-opening polymerization of the polyglycolic acid resins of Example 1-3 and Comparative Example 1-3 and glycolide of Reference Example. It can be seen from the table that when a glycolic acid oligomer having a high terminal carboxyl group ratio is used, a polyglycolic acid resin having a high Mw is obtained. Moreover, Tc is low compared with a polyglycolic acid homopolymer, and it turns out that it is resin which is easy to control crystallization. A good film was obtained from the polyglycolic acid resin of Example 1-3, and the oxygen permeability coefficient was equivalent to that of the polyglycolic acid homopolymer.

Claims (8)

And glycolic acid oligomer proportion terminal functional group is a carboxyl group is more than 90%, obtained by reacting a di-isocyanate compound, polyglycolic acid which comprises a structural unit represented by the following formula (1) Resin.

In (Equation (1), R is a di-isocyanate residues, carbon atoms containing a hydrocarbon group or an aromatic ring having 3 to 20 carbon atoms include aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic structure Represents 6 to 20 hydrocarbon groups.)   The weight average molecular weight (Mw2) of the polyglycolic acid resin is at least three times the weight average molecular weight (Mw1) of the glycolic acid oligomer, and Mw2 is 90,000 or more. Polyglycolic acid resin. In differential scanning calorimetry, the melting point (Tm) (peak top of the melting peak) in the second run when heated at a heating rate of 10 ° C./min is 200 ° C. ≦ Tm ≦ 220 ° C., and the heat history at 240 ° C. 3. The polyglycol according to claim 1, wherein a crystallization point (Tc) (peak top of a crystallization peak) at a cooling rate of 10 ° C./min after receiving is 90 ° C. ≦ Tc ≦ 150 ° C. 4. Acid resin. And glycolic acid oligomer proportion terminal functional group is a carboxyl group is more than 90% in any one of claims 1 to 3, comprising the step of reacting the presence of the amidation catalyst and di isocyanate compound The manufacturing method of the polyglycolic acid-type resin of description. 5. The production of a polyglycolic acid resin according to claim 4 , wherein the amidation catalyst contains at least one metal selected from the group of metals belonging to Groups 1, 2 and 3 of the periodic table. Method. The method for producing a polyglycolic acid resin according to claim 4 , wherein the amidation catalyst contains magnesium or calcium. The method for producing a polyglycolic acid resin according to any one of claims 4 to 6 , wherein the reaction is performed in a molten state of the glycolic acid oligomer. The molded object containing the polyglycolic acid-type resin of any one of Claims 1-3 .