JP2022077948A - Polymer composition - Google Patents

Abstract

To provide a polymer composition excellent in biodegradability while sustaining combination of a low Young's modulus and a high tensile strength, and a molded body of the same.SOLUTION: A polymer composition includes: a dilactide/ε-caprolactone copolymer (C) (hereinafter referred to as a copolymer (C)) having a weight average molecular weight of 60,000 or more; and a dilactide/ε-caprolactone copolymer (D) (hereinafter referred to as a copolymer (D)) having a weight average molecular weight of less than 60,000, where the R value represented by formula (1) of each of the copolymer (C) and the copolymer (D) is 0.45 or more and 0.99 or less, the weight ratio of the copolymer (C) and the copolymer (D) is copolymer (C):copolymer (D)=71:29-99:1. R=[AB]/(2[A][B])×100 formula (1), where [A] is a mole fraction (%) of a dilactide residue in the dilactide/ε-caprolactone copolymer, [B] is a mole fraction (%) of an ε-caprolactone residue in the dilactide/ε-caprolactone copolymer, and [AB] is a mole fraction (%) of a structure (A-B and B-A) such that a dilactide residue and an ε-caprolactone residue are adjacent to each other in the dilactide/ε-caprolactone copolymer.SELECTED DRAWING: None

Description

The present invention relates to a polymer composition containing a high molecular weight dilactide / ε-caprolactone copolymer and a low molecular weight dilactide / ε-caprolactone copolymer and a molded product thereof.

Synthetic polymers are superior to natural polymers in terms of controlled degradation rates and mechanical properties. In particular, polyesters produced from ester bond-forming monomers represented by polylactic acid, polyglycolic acid, polycaprolactone or copolymers thereof are attracting attention as biodegradable or bioabsorbable polymers, for example, suture threads. It is used in various fields such as medical materials such as pharmaceuticals, pesticides, and sustained release materials such as fertilizers. Further, it is expected as a biodegradable general-purpose plastic and as a packaging material for containers and films.

However, in general, biodegradable polyesters and bioabsorbable polyesters produced from ester bond-forming monomers often have insufficient mechanical properties for the purpose of use. Therefore, various copolymers have been tried to be developed for the purpose of improving the mechanical properties and obtaining a biodegradable polymer having strength and moldability that can withstand practical use.

For example, as a method for improving flexibility, Patent Document 1 discloses a method for improving flexibility by controlling the randomness of a monomer sequence.

Attempts have also been made to improve mechanical properties by mixing biodegradable polymers. For example, a composition having improved strength, flexibility, elongation, toughness, etc., comprises at least one hard synthetic biodegradable polymer and at least one soft synthetic biodegradable polymer, which may be hard or soft. Biodegradable polymer blends (see, eg, Patent Document 2), poly, which have higher strength and / or elongation than each of the biodegradable polymers alone and are suitable for formation into at least one of the sheets or films. A resin composition containing lactic acid, an L-lactide / ε-caprolactone copolymer, and a filler (see, for example, Patent Document 3) has been proposed.

International Publication No. 2019/035357 Japanese Patent No. 5530072 Japanese Patent No. 6616724

An ideal bioabsorbable material is required to completely degrade and disappear from the transplant site over a period of time while satisfying time-dependent mechanical requirements. Therefore, it is important to control the decomposition rate of the bioabsorbable material without significantly affecting the mechanical properties. However, although the methods described in Patent Documents 1 to 3 are recognized for improving mechanical properties such as flexibility and strength, they do not mention both mechanical properties and biodegradability, and are used for medical purposes. Needed further improvement.

Therefore, an object of the present invention is to provide a polymer composition having excellent biodegradability and a molded product thereof while maintaining both a low Young's modulus and a high tensile strength.

The present invention for solving the above problems is as follows.

Dilactide / ε-caprolactone copolymer (C) having a weight average molecular weight of 60,000 or more (hereinafter referred to as copolymer (C)), and dilactide / ε- having a weight average molecular weight of less than 60,000. A polymer composition containing a caprolactone copolymer (D) (hereinafter referred to as a copolymer (D)).
The R value represented by the formula (1) of the copolymer (C) and the copolymer (D) is 0.45 or more and 0.99 or less.
A polymer composition in which the weight ratio of the copolymer (C) to the copolymer (D) is copolymer (C): copolymer (D) = 71: 29 to 99: 1.

R = [AB] / (2 [A] [B]) × 100 ・ ・ ・ Equation (1)
[A]: Mole fraction (%) of the dilactide residue in the dilactide / ε-caprolactone copolymer.
[B]: Mole fraction (%) of the ε-caprolactone residue in the dilactide / ε-caprolactone copolymer.
[AB]: Mole fraction (%) of the structure (AB and BA) in which the dilactide residue and the ε-caprolactone residue are adjacent to each other in the dilactide / ε-caprolactone copolymer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a polymer composition and a molded product thereof which are excellent in biodegradability or bioabsorbability and suitable for medical use and elastomer use while maintaining both low Young's modulus and high tensile strength.

The present invention comprises a dilactide / ε-caprolactone copolymer (C) having a weight average molecular weight of 60,000 or more (hereinafter referred to as a copolymer (C)) and a weight average molecular weight of less than 60,000. A polymer composition containing a dilactide / ε-caprolactone copolymer (D) (hereinafter referred to as a copolymer (D)), which is a polymer composition (C) and a copolymer (D), respectively. The R value represented by the formula (1) is 0.45 or more and 0.99 or less, and the weight ratio of the copolymer (C) to the copolymer (D) is the copolymer (C): copolymer. It is a polymer composition having a polymer (D) = 71: 29 to 99: 1.

R = [AB] / (2 [A] [B]) × 100 ・ ・ ・ Equation (1)
[A]: Mole fraction (%) of the dilactide residue in the dilactide / ε-caprolactone copolymer.
[B]: Mole fraction (%) of the ε-caprolactone residue in the dilactide / ε-caprolactone copolymer.
[AB]: Mole fraction (%) of the structure (AB and BA) in which the dilactide residue and the ε-caprolactone residue are adjacent to each other in the dilactide / ε-caprolactone copolymer.
<Dilactide / ε-caprolactone copolymer>
The copolymer (C) and the copolymer (D), which are dilactide / ε-caprolactone copolymers in the polymer composition of the present invention, each have an R value of 0.45 or more represented by the formula (1). It is 99 or less.

R = [AB] / (2 [A] [B]) × 100 ・ ・ ・ Equation (1)
[A]: Mole fraction (%) of the dilactide residue in the dilactide / ε-caprolactone copolymer.
[B]: Mole fraction (%) of the ε-caprolactone residue in the dilactide / ε-caprolactone copolymer.
[AB]: Mole fraction (%) of the structure (AB, and BA) in which the dilactide residue and the ε-caprolactone residue are adjacent to each other in the dilactide / ε-caprolactone copolymer.

The R value can be determined by quantifying the proportion of combinations (AA, BB, AB, BA) of two adjacent monomers by nuclear magnetic resonance (NMR) measurement. Specifically, the dilactide / ε-caprolactone copolymer was dissolved in deuterated chloroform, and the ratio of the dilactide residue to the ε-caprolactone residue in the dilactide / ε-caprolactone copolymer was determined by 1H ^- NMR analysis. calculate. In addition, by the 1H ^homospin decoupling method, the methine group of dilactide (around 5.10 ppm), the α-methylene group of ε-caprolactone (around 2.35 ppm), and the ε methylene group (around 4.10 ppm) are adjacent monomers. Residues are separated by a signal derived from lactide or ε-caprolactone and the peak area of each is quantified. [AB] of Equation 1 is calculated from each area ratio, and the R value is calculated. Here, [AB] is a mole fraction (%) of a structure in which a dilactide residue and a ε-caprolactone residue are adjacent to each other, and specifically, of AA, AB, BA, and BB. It is the ratio of the number of AB and BA to the total number.

The R value is used as an index showing the randomness of the sequence of the monomer residues in the dilactide / ε-caprolactone copolymer. For example, a random copolymer with a completely random monomer sequence has an R value of 1. When the R value is less than 0.45, the crystallinity is high, and the molded product of the copolymer becomes hard and the Young's modulus may increase. Therefore, the R value is preferably 0.45 or more, and from the same viewpoint. The R value is more preferably 0.50 or more. Further, when the R value exceeds 0.99, the copolymer molded product becomes too soft and exhibits adhesiveness, which may reduce the handleability. Therefore, the R value is preferably 0.99 or less. From the same viewpoint, the R value is more preferably 0.85 or less, and even more preferably 0.80 or less.

The bonding mode between the monomers of the dilactide / ε-caprolactone copolymer is not particularly limited and may be linear, branched or cyclic, but in order to achieve both low Young's modulus and high tensile strength, dilactide / ε -The caprolactone copolymer is preferably linear.

The weight average molecular weight of the dilactide / ε-caprolactone copolymer ((copolymer (C)) is preferably 60,000 or more from the viewpoint of further reducing the Young ratio of the polymer composition and further improving the tensile strength. 100,000 or more is more preferable, and 150,000 or more is even more preferable. On the other hand, the weight average molecular weight of the copolymer (C) is 500,000 or less from the viewpoint of the viscosity and solubility of the polymer composition described later. The weight average molecular weight of the dilactide / ε-caprolactone copolymer (copolymer (D)) is preferably less than 60,000, more preferably 40,000 or less, still more preferably 20,000 or less, on the other hand. The weight average molecular weight of the copolymer (D) is preferably 1,000 or more. Here, the weight average molecular weight of the dilactide / ε-caprolactone copolymer refers to a polystyrene-equivalent value, and is measured by gel permeation chromatography (GPC). Can be measured.

The glass transition temperature (Tg) of the copolymer (C) is preferably 0 ° C. or lower. When the glass transition temperature (Tg) of the copolymer (C) is 0 ° C. or lower, processability can be enhanced at room temperature and flexibility can be exhibited. Further, the glass transition temperature (Tg) of the copolymer (C) is more preferably −10 ° C. or lower. The lower limit is not particularly limited, but is preferably −30 ° C. or higher.

In the present invention, the dilactide / ε-caprolactone copolymer (C) and the dilactide / ε-caprolactone copolymer (D) have a gradient structure in which the dilactide residue and the ε-caprolactone residue form a composition gradient in the skeleton. It is preferable to have a structure in which two or more macromer units having the above are linked.

The gradient structure having a composition gradient in the skeleton means a structure in which the composition of the monomer residue continuously changes from the polymerization initiation end to the polymerization termination end along the molecular chain.
Schematically, for example, residue A and residue B are AAAAABAAABAABBABABBBBBABBBB
Line up like.

The dilactide / ε-caprolactone copolymer (C) and / or the copolymer (D) has a gradient structure in which the dilactide residue and the ε-caprolactone residue form a composition gradient in the skeleton. Compared with the case of having a structure, the degree of crystallization can be suppressed and flexibility can be obtained.

The randomness of the distribution of the monomer residues constituting the dilactide / ε-caprolactone copolymer (C) and the copolymer (D) changes depending on the difference in the reactivity of the monomers during polymerization. That is, at the time of polymerization, if one of dilactide and caprolactone is followed by the same monomer and the other monomer with the same probability, a random copolymer in which the monomer residues are completely randomly distributed can be obtained. However, if either monomer tends to bond after one monomer, a gradient copolymer with a biased distribution of monomer residues can be obtained.

Here, the reactivity of dilactide and ε-caprolactone is significantly different as described in the literature (D.W. Grijpmateal. Polymer Bulletin 25, 335, 341), and dilactide has a higher initial polymerization rate than ε-caprolactone. big. The initial polymerization rate _VA of dilactide is 3.6% / h in terms of reaction rate (%), and the initial polymerization rate VA of ε _- caprolactone is 0.88% / h. When dilactide and ε-caprolactone are copolymerized, dilactide tends to bind after dilactide. Therefore, a gradient structure is formed in which the proportion of dilactide units gradually decreases from the polymerization initiation end to the polymerization termination end.

That is, according to a copolymerization method in which a monomer of dilactide and ε-caprolactone are mixed and reacted, in general, the dilactide / ε-caprolactone copolymer tends to form a gradient structure over the entire skeleton of the polymer.

Further, in the present invention, it is preferable that the dilactide / ε-caprolactone copolymer (C) and the copolymer (D) have a gradient structure in macromer units and have a structure in which two or more macromer units are linked.

In general, macromer means a high molecular weight compound having a polymerizable functional group, and in the polymer, the macromer unit forms a part of the skeleton of the polymer. In a structure in which two or more macromer units having a gradient structure are connected, for example,
(AAABAABBBABBB) ・ (AAABAABBBABBB)
Line up like.

Hereinafter, the macromer having a gradient structure is also referred to as a "gradient macromer", and the unit of the gradient macromer in the polymer is also referred to as a "gradient macromer unit".

By having a structure in which two or more gradient macromer units are linked, even if the degree of polymerization is increased, the randomness-controlled dilactide / ε-caprolactone copolymer (C) is effectively as described in (1) above. ), And it can be a dilactide / ε-caprolactone copolymer (C) whose crystallinity is effectively suppressed. Therefore, according to such a preferred embodiment, a polymer composition having a low Young's modulus and a high tensile strength can be effectively obtained.

The number of macromer units in the structure in which the macromer units are connected is preferably 3 or more, and more preferably 6 or more, from the viewpoint of further improving the tensile strength. On the other hand, from the viewpoint of appropriately suppressing the viscosity and improving the handleability, the number of connected macromer units is preferably 20 or less.

In the present invention, the tensile strength when the dilactide / ε-caprolactone copolymer (C) is used as a film is preferably 5 MPa or more, more preferably 10 MPa or more. Further, the larger the tensile strength is, the more preferable it is, and there is no particular upper limit, but in reality, it is considered that the upper limit is about 500 MPa. Further, the Young's modulus of the dilactide / ε-caprolactone copolymer is preferably 0.1 MPa or more, more preferably 1.0 MPa or more. Further, 15 MPa or less is preferable, and 6.3 MPa or less is more preferable.

Keeping the tensile strength and Young's modulus of the dilactide / ε-caprolactone copolymer (C) within the above ranges means that two or more of the above-mentioned gradient macromer units are linked by a production method having a mulching step described later. By making it a structure, it can be effectively achieved.

<Method for producing dilactide / ε-caprolactone copolymer>
The dilactide / ε-caprolactone copolymer is an example.
When the polymerization of dilactide and ε-caprolactone is completed, the sum of the dilactide residue and the ε-caprolactone residue is 50 mol% or more of the total residue, and the dilactide residue and the ε-caprolactone residue are 20 mol of the total residue, respectively. Macromer synthesis step of blending and polymerizing to% or more;
A mulching step of linking the macromers obtained in the macromer synthesis step or adding dilactide and ε-caprolactone to the macromer solution obtained in the macromer synthesis step;
It can be manufactured by the manufacturing method having.

[Macromer synthesis process]
In the macromer synthesis step, the sum of dilactide and ε-caprolactone is theoretically 50 mol% or more of the total residue when the polymerization is completed, and the dilactide residue and ε-caprolactone residue. Is 20 mol% or more of each residue, and the polymerization is carried out. As a result, a dilactide / ε-caprolactone copolymer containing a dilactide residue and a ε-caprolactone residue as a main constituent unit can be obtained. From now on, the dilactide / ε-caprolactone copolymer obtained by this step will be referred to as "macromer".

In this step, due to the difference in the initial polymerization rate between dilactide and ε-caprolactone, a macromer having a gradient structure in which the dilactide residue and the ε-caprolactone residue form a composition gradient in the skeleton is obtained.

In the macromer synthesis step, in order to realize such a gradient structure, it is desirable to synthesize macromer by a polymerization reaction occurring in one direction from the start terminal. As such a synthetic reaction, it is preferable to use ring-opening polymerization or living polymerization.

An example of a method for synthesizing lactide / caprolactone macromer will be described more specifically. First, dilactide, ε-caprolactone and a catalyst are placed in a reaction vessel equipped with a stirrer and stirred while heating under a nitrogen stream. In order to remove the water content inside the reaction vessel, it is preferable to reduce the pressure of the reaction vessel and heat and stir.

As the stirrer, a stirrer provided with a propeller type stirring blade is preferable, and the rotation speed of the stirring blade is preferably 50 rpm or more and 200 rpm or less.

The heating temperature of the polymerization reaction is preferably 100 ° C. or higher and 250 ° C. or lower. The reaction time of the polymerization reaction is preferably 3 hours or more, more preferably 5 hours or more, still more preferably 7 hours or more, from the viewpoint of increasing the degree of polymerization. On the other hand, the reaction time of the polymerization reaction is preferably 24 hours or less from the viewpoint of further improving productivity.

Dilactide and ε-caprolactone are preferably used after being purified in advance in order to remove impurities.

Examples of the catalyst include tin octylate, antimony trifluoride, zinc powder, dibutyltin oxide, tin oxalate and the like. Examples of the method of adding the catalyst to the reaction system include a method of adding the catalyst dispersed in the raw material at the time of charging the raw material, and a method of adding the catalyst dispersed in the medium at the start of depressurization or immediately before the start of heating in the above-mentioned method. The method etc. can be mentioned. From the viewpoint of shortening the reaction time and further improving the productivity, the amount of the catalyst used is preferably 0.01 part by weight or more in terms of metal atom with respect to 100 parts by weight of the total of dilactide and ε-caprolactone. 04 parts by weight or more is more preferable. On the other hand, the amount of the catalyst used is 0.5 parts by weight in terms of metal atom with respect to the total amount of dilactide and ε-caprolactone from the viewpoint of further reducing the amount of metal remaining in the dilactide / ε-caprolactone copolymer. The following is preferred.

When water is used as the co-initiator, it is preferable to carry out a co-catalytic reaction at around 90 ° C. prior to the polymerization reaction.

The macromer obtained in this step has the dilactide / ε-caprolactone copolymer weight described in (1) above in order to facilitate the production of a dilactide / ε-caprolactone copolymer finally satisfying the R value shown in (1) above. Those having the same R value as coalescence, that is, the following formula R value = [AB] / (2 [A] [B]) × 100
[A]: Mole fraction (%) of dilactide residues in macromer
[B]: Mole fraction (%) of ε-caprolactone residue in macromer
[AB]: Mole fraction (%) of the structure (AB, and BA) in which the dilactide residue and the ε-caprolactone residue are adjacent to each other in the macromer.
The R value represented by is preferably 0.45 or more and 0.99 or less, and more preferably 0.50 or more and 0.80 or less.

The weight average molecular weight of the macromer synthesized in the macromer synthesis step is preferably 10,000 or more, more preferably 20,000 or more. Further, in order to further reduce the crystallinity and further improve the flexibility, it is preferably 150,000 or less, and more preferably 100,000 or less.

[Multi-layering process]
In the mulching step, the macromers obtained in the macromer synthesis step are linked to each other, or dilactide and caprolactone are added to the macromer solution obtained in the macromer synthesis step to mulch. In this step, macromers obtained in one macromer synthesis step may be linked to each other, or a plurality of macromers obtained in two or more macromer synthesis steps may be linked. In addition, "multiplying" means that by any of these methods, a dilactide residue and a caprolactone residue form a structure in which a plurality of molecular chains having a gradient structure having a composition gradient are repeated in the skeleton. do.

The number of linkages in macromer units can be adjusted by the catalyst used in the mulching process and the reaction time. When mulching by connecting macromers to each other, the number of macromer units can be obtained by dividing the weight average molecular weight of the finally obtained dilactide / ε-caprolactone copolymer by the weight average molecular weight of macromers. can.

The reaction temperature of the condensation reaction in the mulching step is preferably 20 ° C. or higher from the viewpoint of efficiently advancing the condensation reaction. On the other hand, the reaction temperature of the condensation reaction is preferably 50 ° C. or lower from the viewpoint of suppressing the volatilization of the solvent. The reaction time of the condensation reaction is preferably 15 hours or more from the viewpoint of keeping the number of macromer units to be mulched within the above-mentioned preferable range. On the other hand, the reaction time of the condensation reaction is preferably 24 hours or less from the viewpoint of narrowing the molecular weight distribution.

In the case of producing a linear dilactide / ε-caprolactone copolymer, for example, it can be synthesized by binding one molecule of the same gradient macromer to both ends of the gradient macromer via the ends.

When the gradient macromer has a hydroxyl group and a carboxyl group at each terminal, a mulched dilactide / ε-caprolactone copolymer can be obtained by condensing the ends with a condensing agent. Examples of the condensing agent include p-toluenesulfonic acid 4,4-dimethylaminopyridinium, N, N'-dicyclohexylcarbodiimide, N, N'-diisopropylcarbodiimide, N, N'-carbonyldiimidazole and the like. Two or more of these may be used.

If the polymerization reaction has a living property, that is, if the polymerization reaction can be started continuously from the end of the polymer, dilactide and ε-caprolactone are added to the gradient macromer solution after the polymerization reaction is completed. By repeating the operation, it can be multi-layered.

Alternatively, the gradient macromers may be mulched via a linker to the extent that they do not affect the mechanical properties of the polymer. In particular, a linker having multiple carboxyl groups and / or multiple hydroxy groups, for example 2,2-bis (hydroxymethyl) propionic acid, is used to synthesize a branched polyester copolymer in which the linker is a branch point. Can be done.

The dilactide / ε-caprolactone copolymer obtained by the above-mentioned production method is a copolymer having a structure in which two or more macromer units having a composition gradient in the skeleton of the dilactide residue and the caprolactone residue are linked. It is a preferred embodiment of the dilactide / ε-caprolactone copolymer of the present invention.

<Polymer composition>
The polymer composition of the present invention has a dilactide / ε-caprolactone copolymer (C) having a weight average molecular weight of 60,000 or more (hereinafter referred to as a copolymer (C)) and a weight average molecular weight of less than 60,000. Dilactide / ε-caprolactone copolymer (D) (hereinafter referred to as copolymer (D)) is contained.

Further, both the copolymer (C) and the copolymer (D) have an R value represented by the above formula (1) of 0.45 or more and 0.99 or less. The dilactide / ε-caprolactone satisfying the above formula (1) has a low crystallization rate, can reduce Young's modulus, and can improve the tensile strength, while the biodegradable behavior depends on the molecular weight.

The polymer composition of the present invention preferably contains the copolymer (C) and the copolymer (D) in a total of 50% by weight or more and 100% by weight or less in 100% by weight of the polymer composition. By containing the copolymer (C) and the copolymer (D) in a total of 50% by weight or more and 100% by weight or less in 100% by weight of the polymer composition, while maintaining both low Young's modulus and high tensile strength. , It is preferable because the biodegradability can be controlled. The total content of the copolymer (C) and the copolymer (D) in 100% by weight of the polymer composition is more preferably 70% by weight or more and 100% by weight or less, and 90% by weight or more and 100% by weight or less. Is particularly preferred. The biodegradability can be controlled according to the ratio of the copolymer (D) while maintaining both a low Young's modulus and a high tensile strength.

Further, the weight ratio of the copolymer (C) to the copolymer (D) is preferably copolymer (C): copolymer (D) = 71: 29 to 99: 1, and is low. The biodegradability can be controlled according to the ratio of the copolymer (D) while maintaining both the rate and the high tensile strength. The weight ratio of the copolymer (C) to the copolymer (D) is preferably copolymer (C): copolymer (D) = 80: 20 to 95: 5, and 85: 15 to 92. : 8 is particularly preferable.

In the polymer composition of the present invention, the Young's modulus measured according to JIS K6251 (2017) is preferably 0.1 MPa or more, more preferably 1.0 MPa or more. The upper limit is preferably 15.0 MPa or less, more preferably 6.3 MPa or less, and even more preferably 3.0 MPa or less. The Young's modulus of the polymer composition of the present invention measured according to JIS K6251 (2017) means the Young's modulus measured according to JIS K6251 (2017) when the polymer composition of the present invention is used as a film. .. This measuring method is as described in Measurement Example 4 described later.

The polymer composition of the present invention preferably has a tensile strength of 5 MPa or more, more preferably 10 MPa or more, as measured according to JIS K6251 (2017). Further, the larger the tensile strength is, the more preferable it is, and there is no particular upper limit, but in reality, it is considered that the upper limit is about 500 MPa. The tensile strength of the polymer composition of the present invention measured according to JIS K6251 (2017) means the tensile strength measured according to JIS K6251 (2017) when the polymer composition of the present invention is used as a film. do. This measuring method is as described in Measurement Example 4 described later.

In the polymer composition of the present invention, the elongation at break measured according to JIS K6251 (2017) is preferably 200% or more, more preferably 500% or more, still more preferably 1000% or more. .. The larger the elongation at break is, the more preferable it is, and there is no particular upper limit, but in reality, it is considered that the upper limit is about 2500%. The breaking elongation of the polymer composition of the present invention measured according to JIS K6251 (2017) is the breaking elongation when measured according to JIS K6251 (2017) when the polymer composition of the present invention is used as a film. Means degree. This measuring method is as described in Measurement Example 4 described later.

<Manufacturing method of polymer composition and molded product>
The polymer composition of the present invention can be obtained, for example, by stirring the above-mentioned copolymer (C) and the above-mentioned copolymer (D) in a molten state or a solution state. From the viewpoint of suppressing thermal decomposition, it is preferable to stir in a solution state. More preferably, each polymer constituting the polymer composition is put together in the same solvent and dissolved with stirring, and then the solvent is volatilized and removed.

Further, such a polymer composition can be molded by a melt molding method, a solvent molding method, an electrolytic spinning method, or a molding method using a 3D printer. The melt molding method is a method in which a polymer composition is heated and melted and molded using a mold, an extrusion molding machine, a press machine, or the like, and can be molded into a fibrous shape, a film shape, a tubular shape, or the like. For example, the polymer composition described in the present invention can be heated to 200 ° C. in an extruder set with a φ1 mm base and extruded to form a polymer into a thread shape, and the fibers can be woven or knitted. can. The solvent molding method is a method in which a polymer composition is dissolved in a solvent, injected into a mold or a coagulation bath, and the solvent and the solute are separated to form the polymer composition into a fibrous form, a film form, a tubular form, or the like. Can be done. As an example of the solvent molding method, a rod having a diameter of 0.5 to 20 mm is immersed in a polymer composition solution in which 20% is dissolved in chloroform, pulled up, waited for the solvent to volatilize, and then immersed again 5 to 50 times. It can be molded into a tube shape by repeating it to some extent and finally pulling out the core rod.

The electrolytic spinning method is a technique capable of producing a fiber structure composed of nanofibers having a diameter of several nanometers by applying a high voltage to a polymer solution in a spinning nozzle. The thickness can be adjusted to a desired range. For example, a tubular fiber structure can be produced by accumulating fibers made of a polymer composition while rotating a columnar collector and then pulling out the collector from the fiber structure.

Further, by using such a polymer composition as an ink material for a 3D printer, various custom-made structures can be produced.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Measurement Example 1: Measurement of mole fraction and R value of each residue by nuclear magnetic resonance (NMR))
The dilactide / ε-caprolactone copolymer to be measured was dissolved in deuterated chloroform, and the ratios of dilactide residue and caprolactone residue in the dilactide / ε-caprolactone copolymer were calculated by 1H ^- NMR under the following conditions. .. In addition, by the 1H ^homospin decoupling method, the methine group of lactide (around 5.10 ppm), the α-methylene group of caprolactone (around 2.35 ppm), and the ε-methylene group (around 4.10 ppm) are adjacent monomer residues. Was separated by a signal derived from lactide or caprolactone, and the peak area of each was quantified. [AB] of Equation 1 was calculated from each area ratio, and the R value was calculated. Here, [AB] is the mole fraction (%) of the structure in which the dilactide residue and the caprolactone residue are adjacent to each other, and specifically, the total number of AA, AB, BA, and BB. It is the ratio of the number of AB and BA to B.
The results are shown in Table 1.
Device name: JNM-EX270 (manufactured by JEOL Ltd.)
¹ H homospin decoupling irradiation position: 1.66ppm
Solvent: Deuterated chloroform Measurement temperature: Room temperature.

(Measurement Example 2: Measurement of weight average molecular weight by gel permeation chromatography (GPC))
The dilactide / ε-caprolactone copolymer to be measured was dissolved in chloroform and passed through a 0.45 μm syringe filter (DISMIC-13HP; manufactured by ADVANTEC) to remove impurities and the like. Then, the polystyrene-equivalent weight average molecular weights of the dilactide / ε-caprolactone copolymer and polylactic acid were calculated by GPC measurement under the following conditions. The results are shown in Table 1.
Device name: Prominence (manufactured by Shimadzu Corporation)
Mobile phase: Chloroform (for HPLC) (manufactured by Wako Pure Chemical Industries, Ltd.)
Flow velocity: 1 mL / min
Column: TSKgel GMHHR-M (φ7.8mmX300mm; manufactured by Tosoh Corporation)
Detector: The UV detector (254 nm) and the RI detector were activated, and the results from the RI detector were used to calculate the weight average molecular weight.
Column, detector temperature: 35 ° C
Standard material: Polystyrene.

(Measurement Example 3: Measurement of Tg by Differential Scanning Calorimetry (DSC))
The dilactide / ε-caprolactone copolymer to be measured was sampled on an aluminum PAN, and the glass transition temperature (Tg) was measured by the DSC method under the following conditions using a differential scanning calorimeter (EXTAR 6000; manufactured by Seiko Instruments Inc.). Calculated.
Device name: EXSTAR 6000 (manufactured by Seiko Instruments Inc.)
Temperature conditions: In order, temperature rises to 250 ° C at 25 ° C> 10 ° C / min> heat retention for 5 min at 250 ° C> lowers to -70 ° C at 10 ° C / min> temperature rises to 250 ° C at 10 ° C / min> 250 ° C Insulation for 5 min> 100 ° C / min to 25 ° C Standard substance: Aluminum. The results are shown in Table 2.

(Measurement example 4: Young's modulus, tensile strength, and breaking elongation measured by tensile test)
The high molecular weight polymer and the low molecular weight polymer are mixed in various ratios, dissolved in chloroform so that the concentration of the mixture is 5% by weight, the solution is transferred onto a Teflon chalet, and the solution is transferred to a Teflon chalet overnight at normal pressure and room temperature. It was dried. This was dried under reduced pressure at 50 ° C. overnight to obtain a polyester copolymer film.

The obtained polyester copolymer film (thickness 0.1 mm) was cut into strips (30 mm × 5 mm) and subjected to a tensile test under the following conditions according to JIS K6251 (2017) to calculate Young's modulus, tensile strength, and elongation at break. .. Table 2 shows the results of measuring 5 times each and calculating the average value of the numbers.

Device name: EZ-LX (manufactured by Shimadzu Corporation)
Initial length: 10 mm
Tensile speed: 500 mm / min
Load cell: 1kN
Number of tests: 5 times.

<Example 1>
[Synthesis of Polymer 1]
100.0 g of L-dilactide (manufactured by PURAC) and 79.2 g of εcaprolactone (manufactured by Wako Pure Chemical Industries, Ltd.) were collected in a separable flask as monomers. Using these as catalysts, 0.05 parts by mass (tin equivalent value) of tin octylate (II) (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 parts by mass of dilactide and ε-caprolactone in total. A solution dissolved in 5 mL of toluene (ultra-dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.) and hydroxypivalic acid in an amount such that the monomer / initiator ratio is 200 are added as an auxiliary initiator and heated to 145 ° C. Then, the mixture was stirred at a stirring speed of 50 rpm for 12 hours and subjected to a copolymerization reaction to obtain a crude copolymer. The obtained crude copolymer was dissolved in 300 mL of chloroform and added dropwise to 2.5 L of hexane in a stirred state to obtain a precipitate. The precipitate was dried under reduced pressure at 50 ° C. to obtain macromer. The weight average molecular weight of the obtained polymer was 21,000. 30.0 g of the macromer, 1.22 g of the catalyst 4,4-dimethylaminopyridinium p-toluenesulfonic acid (synthetic product), and 0.50 g of 4,4-dimethylaminopyridine (Wako Pure Chemical Industries, Ltd.) Made) was collected. These were placed in a nitrogen atmosphere and dissolved in 120 mL of dichloromethane (dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.). After 1 hour, 0.98 mL of N, N, N'-diisopropylcarbodiimide (Tokyo Kasei Kogyo Co., Ltd.) was added to the dissolved polymer, and condensation polymerization was carried out at room temperature for 1 day.

Add 300 mL of chloroform to the reaction mixture and wash with 300 mL of HCL (0.5 M) in a stirred state for about 20 minutes. The upper aqueous layer was removed and the lower organic layer was further washed with an equal volume of water at least 4 times until the pH was neutral. Finally, the upper aqueous layer was removed and the lower organic layer was precipitated in 2 L of MeOH.

The precipitate was dried under reduced pressure at 50 ° C. to obtain a purified polyester copolymer. The obtained polymer had a mole fraction of dilactide residues of 50%, a molar fraction of ε-caprolactone of 50%, a weight average molecular weight of 240,000, and an R value of 0.80. The Tg was -10.5 ° C.

[Synthesis of polymer 2]
48.4 g of L-lactide (PURASORB L; manufactured by PURAC) and 39.4 g of ε-caprolactone (manufactured by Wako Pure Chemical Industries, Ltd.) were collected in a separable flask as monomers. Using these as catalysts, 0.05 parts by mass (tin equivalent value) of tin octylate (II) (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 parts by mass of the total of dilactide and ε-caprolactone. A solution dissolved in 5 mL of toluene (ultra-dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.) and D, L-lactic acid in an amount such that the monomer / initiator ratio is 33 are added as an auxiliary initiator, and the temperature is 145 ° C. The copolymerization reaction was carried out for 9 hours to obtain a crude copolymer.

The obtained crude copolymer was dissolved in 100 mL of chloroform and added dropwise to 1 L of hexane in a stirred state to obtain a precipitate. The precipitate was dried under reduced pressure at 50 ° C. to obtain macromer. The mole fraction of the dilactide residue of the obtained polymer was 53%, the mole fraction of ε-caprolactone was 47%, the weight average molecular weight was 7,800, and the R value was 0.70.

980 mg of Polymer 1 and 20 mg of Polymer 2 are dissolved in chloroform to a concentration of 5% by weight, the solution is transferred onto a Teflon chalet, and dried at normal pressure and room temperature overnight. This was dried under reduced pressure, and a polymer film having a thickness of 0.1 mm was cut into strips (30 mm × 5 mm) and subjected to a tensile test. The tensile strength was 26.0 MPa, the Young's modulus was 2.7 MPa, and the elongation at break was 1057%. The Tg of the composition is -11.5 ° C.
Met.

<Example 2>
900 mg of polymer 1 and 100 mg of polymer 2 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 19.3 MPa, the Young's modulus was 2.5 MPa, and the elongation at break was 1059%. The Tg of the composition was -12.3 ° C.

<Example 3>
[Synthesis of Polymer 3]
50.0 g of L-dilactide (manufactured by PURAC) and 39.4 g of ε-caprolactone (manufactured by Wako Pure Chemical Industries, Ltd.) were collected in a separable flask as monomers. Using these as catalysts, 0.05 parts by mass (tin equivalent value) of tin octylate (II) (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 parts by mass of dilactide and ε-caprolactone in total. A solution dissolved in 5 mL of toluene (ultra-dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.) and hydroxypivalic acid in an amount such that the monomer / initiator ratio is 200 are added as an auxiliary initiator and heated to 145 ° C. Then, the mixture was stirred at a stirring rate of 50 rpm for 9.5 hours and subjected to a copolymerization reaction to obtain a crude copolymer.

The obtained crude copolymer was dissolved in 100 mL of chloroform and added dropwise to 1000 mL of hexane in a stirred state to obtain a precipitate. The precipitate was dried under reduced pressure at 50 ° C. to obtain macromer. The weight average molecular weight of the obtained polymer was 19,000, and the R value was 0.80.
980 mg of polymer 1 and 20 mg of polymer 3 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 25.7 MPa, the Young's modulus was 2.7 MPa, and the elongation at break was 1170%. The Tg of the composition was -10.9 ° C.

<Example 4>
900 mg of polymer 1 and 100 mg of polymer 3 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 16.3 MPa, the Young's modulus was 2.6 MPa, and the elongation at break was 1160%. The Tg of the composition was -11.0 ° C.

<Example 5>
[Synthesis of polymer 4]
100.0 g of L-dilactide (manufactured by PURAC) and 79.2 g of ε-caprolactone (manufactured by Wako Pure Chemical Industries, Ltd.) were collected in a separable flask as monomers. Using these as catalysts, 0.05 parts by mass (tin equivalent value) of tin octylate (II) (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 parts by mass of dilactide and ε-caprolactone in total. A solution dissolved in 5 mL of toluene (ultra-dehydrated) (manufactured by Wako Pure Chemical Industries, Ltd.) and hydroxypivalic acid in an amount such that the monomer / initiator ratio is 200 are added as an auxiliary initiator and heated to 150 ° C. Then, the mixture was stirred at a stirring rate of 50 rpm for 9.5 hours and subjected to a copolymerization reaction to obtain a crude copolymer.

The obtained crude copolymer was dissolved in 360 mL of chloroform and added dropwise to 2500 mL of hexane in a stirred state to obtain a precipitate. The precipitate was dried under reduced pressure at 50 ° C. to obtain macromer. The weight average molecular weight of the obtained polymer was 53,000, and the R value was 0.78.
980 mg of polymer 1 and 20 mg of polymer 4 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 13.9 MPa, the Young's modulus was 2.6 MPa, and the elongation at break was 1270%. The Tg of the composition was -11.1 ° C.

<Example 6>
900 mg of polymer 1 and 100 mg of polymer 4 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 11.1 MPa, the Young's modulus was 2.5 MPa, and the elongation at break was 1341%. The Tg of the composition was -11.9 ° C.

<Comparative Example 1>
1000 g of polymer 1 was dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 27.8 MPa, the Young's modulus was 3.6 MPa, and the elongation at break was 953%. The Tg of the composition was -10.5 ° C.

<Comparative Example 2>
700 mg of polymer 1 and 300 mg of polymer 2 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 14.8 MPa, the Young's modulus was 3.5 MPa, and the elongation at break was 1155%. The Tg of the composition was -13.8 ° C.

<Comparative Example 3>
500 mg of polymer 1 and 500 mg of polymer 3 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 8.4 MPa, the Young's modulus was 4.7 MPa, and the elongation at break was 961%. The Tg of the composition was -15.0 ° C.

<Comparative Example 4>
700 mg of polymer 1 and 300 mg of polymer 3 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 12.3 MPa, the Young's modulus was 3.1 MPa, and the elongation at break was 1290%. The Tg of the composition was -12.3 ° C.

<Comparative Example 5>
500 mg of polymer 1 and 500 mg of polymer 3 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 8.6 MPa, the Young's modulus was 5.3 MPa, and the elongation at break was 1339%. The Tg of the composition was -13.5 ° C.

<Comparative Example 6>
700 mg of polymer 1 and 300 mg of polymer 4 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 8.0 MPa, the Young's modulus was 2.4 MPa, and the elongation at break was 1101%. The Tg of the composition was -13.1 ° C.

<Comparative Example 7>
500 mg of polymer 1 and 500 mg of polymer 4 were dissolved in chloroform so as to have a concentration of 5% by weight, a polymer film was prepared by the same method as in Example 1, and a tensile test was performed. The tensile strength was 6.9 MPa, the Young's modulus was 2.7 MPa, and the elongation at break was 1203%. The Tg of the composition was -12.2 ° C.

<Example 7>
980 mg of Polymer 1 and 20 mg of Polymer 3 were dissolved in chloroform to a concentration of 10% by weight, the solution was transferred onto a Teflon chalet, and dried at normal pressure and room temperature overnight. This was dried under reduced pressure at 50 ° C. to obtain a polyester copolymer film.

The dried film was stripped from the petri dish, cut into rectangles (1.5 cm x 3 cm) and then the polymer film was incubated in 10 mL PBS at 37 ° C. At each of the 4th, 8th, and 12th weeks, the film was washed with distilled water, dried overnight in a vacuum oven at 50 ° C., and the molecular weight of the polymer film was measured by GPC as described in Measurement Example 2. .. Further, the rate of change in the molecular weight of the film at each time point was calculated from the following formula (2).

Rate of change in molecular weight of film (%) = Mwx × 100 / Mw0 ・ ・ ・ Equation (2)
Mwx: Weight average molecular weight at each time point of the 4th, 8th, and 12th weeks Mw0: Initial weight average molecular weight <Example 8>
A polymer film was prepared in the same manner as in Example 7 except that the polymer 1 was changed to 900 mg and the polymer 3 was changed to 100 mg. Further, the molecular weight of the polymer film was measured in the same manner as in Example 7, and the rate of change in the molecular weight of the film at each time point was calculated from the above formula (2).

<Comparative Example 8>
A polymer film was prepared in the same manner as in Example 7 except that the polymer 1 was changed to 1000 mg and the polymer 3 was changed to 0 mg. Further, the molecular weight of the polymer film was measured in the same manner as in Example 7, and the rate of change in the molecular weight of the film at each time point was calculated from the above formula (2).

<Comparative Example 9>
A polymer film was prepared in the same manner as in Example 7 except that the polymer 1 was changed to 700 mg and the polymer 3 was changed to 300 mg. Further, the molecular weight of the polymer film was measured in the same manner as in Example 7, and the rate of change in the molecular weight of the film at each time point was calculated from the above formula (2).

Tables 1 to 3 show various measurement results of the polymers and polymer films obtained in Examples 1 to 8 and Comparative Examples 1 to 9.

PDI in the table means a molecular weight distribution.

LA / CL means the mole fraction of lactic acid residues in the polymer / the mole fraction of caprolactone residues.

Mw means the weight average molecular weight.

The low molecular weight polymer means a polymer having a weight average molecular weight of less than 60,000.

The high molecular weight polymer means a polymer having a weight average molecular weight of 60,000 or more.

Specific uses of the polymer composition of the present invention include non-woven fabrics for fibers, disposable toiletry products and cosmetics for containers, packaging films, agricultural multi-films, tapes and the like for films. Other medical uses include sutures, artificial bones, artificial skins, wound dressings, DDS fields such as microcapsules, and scaffolding materials for tissue and organ regeneration. Further, other toners, binders for thermal transfer inks, and the like can be considered, but the use is not limited thereto.

Claims (7)

Dilactide / ε-caprolactone copolymer (C) having a weight average molecular weight of 60,000 or more (hereinafter referred to as copolymer (C)), and dilactide / ε- having a weight average molecular weight of less than 60,000. A polymer composition containing a caprolactone copolymer (D) (hereinafter referred to as a copolymer (D)).
The R value represented by the formula (1) of the copolymer (C) and the copolymer (D) is 0.45 or more and 0.99 or less.
A polymer composition in which the weight ratio of the copolymer (C) to the copolymer (D) is copolymer (C): copolymer (D) = 71: 29 to 99: 1.
R = [AB] / (2 [A] [B]) × 100 ・ ・ ・ Equation (1)
[A]: Mole fraction (%) of the dilactide residue in the dilactide / ε-caprolactone copolymer.
[B]: Mole fraction (%) of the ε-caprolactone residue in the dilactide / ε-caprolactone copolymer.
[AB]: Mole fraction (%) of the structure (AB and BA) in which the dilactide residue and the ε-caprolactone residue are adjacent to each other in the dilactide / ε-caprolactone copolymer. The copolymer (C) and the copolymer (D) both have a structure in which two or more macromer units having a gradient structure in which a dilactide residue and a ε-caprolactone residue form a composition gradient in the skeleton are linked. The polymer composition according to claim 1. The polymer composition according to claim 1 or 2, wherein the glass transition temperature (Tg) of the copolymer (C) is 0 ° C. or lower. The polymer composition according to any one of claims 1 to 3, wherein the copolymer (C) and the copolymer (D) are contained in an amount of 50% by weight or more and 100% by weight or less in total. The polymer composition according to any one of claims 1 to 4, wherein the Young's modulus measured according to JIS K6251 (2017) is 0.1 MPa or more and 15.0 MPa or less. The polymer composition according to any one of claims 1 to 5, wherein the tensile strength as measured according to JIS K6251 (2017) is 5 MPa or more. The polymer composition according to any one of claims 1 to 6, wherein the elongation at break as measured according to JIS K6251 (2017) is 200% or more.