JP7015342B2 - Biodegradable copolymer and its manufacturing method and biodegradability improving method - Google Patents

Description

The present invention relates to a biodegradable copolymer containing 3-hydroxybutyric acid (3-hydroxybutanoic acid or 3HB) units and a method for producing the same, and a method for introducing 3HB into a part of a monomer to improve the biodegradability of the polymer.

From the viewpoint of environmental protection, the use of biodegradable plastics is advancing. Plastics released into the environment require hundreds of years to decompose, drifting over the ocean to form a marine polluted area called a plastic belt, and damaging the growth of birds and animals. Further, minute plastic pieces of 1 mm or less generated in the decomposition process thereof are called small microplastics, and there is a concern that they may cause endocrine disturbance when taken into a living body. Some of these tiny pieces of plastic are artificially added to products such as shampoo and toothpaste in advance, and some areas are beginning to be banned from use.

In addition, the use of biodegradable garbage bags is being promoted mainly in Europe. This garbage bag aims to prevent plastic from remaining when composting garbage. However, in the composting process, all biodegradable garbage bags become carbon dioxide, which is a warming gas. This is because most of the biodegradable garbage bags sold in the past cannot be biogasified under anaerobic conditions and can only be decomposed by the composting process under aerobic conditions.

General-purpose biodegradable plastics used for the garbage bags and the like include polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), and polylactic acid. (PLA) and the like are known. However, as described above, it does not have a sufficient decomposition rate in biogasification under anaerobic conditions, and has low biodegradability in the ocean, for example.

H. Yagi et al., Polymer Degradation and Stability 110 (2014) 278-283 (Non-Patent Document 1) evaluates the biodegradability of various biodegradable polyesters under anaerobic conditions, and PLA and PCL. , It is disclosed that polyhydroxybutyrate (PHB) exhibits higher biodegradability under anaerobic conditions as compared with PBS. As described above, polyhydroxyalkanoates (PHA) such as PHB are plastics having sufficient decomposition performance under anaerobic conditions, while biodegradable plastics other than PHA do not exist in the natural world, and thus are microorganisms existing in the natural world. It only has a structure that can be slowly decomposed by. However, PHA has not been widely used because it lacks the mechanical properties required for a general-purpose plastic molded product and is not economical.

Further, as a biodegradable polymer having excellent mechanical properties, JP-A-8-3296 (Patent Document 1) states that the aliphatic oxycarboxylic acid unit is 98 to 70 mol% and the aliphatic diol unit is 1 to 15 mol. % And an aliphatic polyester copolymer consisting mainly of 1 to 15 mol% of an aliphatic dicarboxylic acid unit and having a number average molecular weight of 10,000 to 100,000 are disclosed. In the examples of this document, copolyesters obtained using L-lactic acid, 1,4-butanediol and succinic acid are produced. However, even this aliphatic polyester copolymer had low biodegradability under anaerobic conditions.

Therefore, improvement in biodegradability of PBS, PBSA, PBAT, PLA, etc., which can be produced at low cost and can replace petroleum-based plastics, is expected.

JP-A-8-3296 (Claim 1, Example)

H. Yagi et al., Polymer Degradation and Stability 110 (2014) 278-283 (Table 1)

Therefore, an object of the present invention is to provide a biodegradable copolymer having excellent biodegradability and excellent mechanical properties, a method for producing the same, and a method for improving biodegradability.

Another object of the present invention is to provide a biodegradable copolymer capable of improving biodegradability under anaerobic conditions, a method for producing the same, and a method for improving biodegradability.

Still another object of the present invention is to provide a biodegradable copolymer which can be easily and inexpensively produced and whose biodegradability can be easily controlled, a method for producing the same, and a method for improving biodegradability.

The present inventors started the study focusing on the high biodegradability of polyhydroxyalkanoic acid, and at the beginning of the study, the oligomer structure of 3-hydroxybutyric acid (3HB) on the polymer chain of the biodegradable plastic. It was assumed that if (repeating unit) could be inserted, the binding portion between 3HBs would undergo microbial decomposition to improve biodegradability. However, as the study progressed, the present inventors surprisingly found that the 3HB monomer (monomer) did not form an oligomer structure, and the 3HB monomer units did not bind to each other alone in the polymer. It was found that the ester bonds between the 3HB monomer and other monomers are easily decomposed by microorganisms in the environment even if they are contained in each of them independently. That is, without preparing a copolymer containing a 3HB oligomer unit through oligomerization of a 3HB monomer, which requires a complicated synthesis process, the 3HB monomer can be added together with other monomers at the time of synthesis to produce a polymer. Succeeded in imparting degradability. Therefore, it has been found that the biodegradability can be imparted only by containing a few percent of the 3HB monomer, and the obtained copolymer can almost maintain the physical characteristics of the original biodegradable plastic. Furthermore, it was also found that the biodegradation rate can be easily adjusted only by adjusting the addition amount of 3HB. This technique is an epoch-making technique capable of imparting biodegradability by mixing a small amount of 3HB with a polymer such as polyester having an ester bond.

That is, the biodegradable copolymer of the present invention contains 3-hydroxybutyric acid units as a constituent unit of the copolymer, and the ratio of the 3-hydroxybutyric acid units is 1 to 20 mol% with respect to all the constituent units of the copolymer. .. The ratio of the 3-hydroxybutyric acid unit may be about 5 to 15 mol% with respect to all the constituent units of the copolymer. The 3-hydroxybutyric acid unit may be introduced at random. The biodegradable copolymer of the present invention may contain an oligomer unit in which both ends of the 3-hydroxybutyric acid unit are bonded to other constituent units. The biodegradable copolymer of the present invention may be a thermoplastic resin such as copolyester. The copolymer of the present invention may further contain a unit having a C _2-10 alkane skeleton. The copolymer of the present invention may further contain a unit having a fluorene skeleton.

The present invention also includes a method for producing the biodegradable copolymer in which a mixture of 3-hydroxybutyric acid or a reactive derivative thereof and another monomer is polymerized.

Further, the present invention also relates to a method for improving the biodegradability of a copolymer by introducing 3-hydroxybutyric acid units into the constituent units of the copolymer at a ratio of 1 to 20 mol% with respect to all the constituent units of the copolymer. included.

In the present invention, the "constituent unit (repeating unit or monomer unit)" of the copolymer means the skeleton or residue derived from the monomer (per monomer) in the copolymer, and for example, "3-hydroxybutyric acid unit (or 3-hydroxybutyric acid unit)". "Unit of hydroxybutyric acid)" means a skeleton or residue derived from 3-hydroxybutyric acid or a reactive derivative thereof in the copolymer. Further, the term "hydroxyalkanoic acid unit" may be used to include a unit derived from a lactone having the same skeleton in the copolymer.

In the present invention, 3-hydroxybutyric acid units (3-hydroxybutyric acid skeleton or 3-hydroxybutyric acid residue) are contained in a proportion of 1 to 20 mol% with respect to all the constituent units of the copolymer, so that they are biodegradable and mechanical. It can be compatible with the characteristics. In particular, not only aerobic conditions but also biodegradability under anaerobic conditions can be improved. In addition, a plastic having high biodegradability can be inexpensively produced by a simple method in which 3-hydroxybutyric acid or a reactive derivative thereof is collectively added and polymerized with another monomer. Furthermore, the biodegradability of the copolymer can be easily controlled by changing the proportion of 3-hydroxybutyric acid units.

FIG. 1 is a graph showing the biodegradability of a polymer under aerobic conditions in Examples. FIG. 2 is a graph showing the biodegradability of the polymer under anaerobic conditions in the examples.

[Biodegradable copolymer]
The biodegradable copolymer of the present invention may contain 3-hydroxybutyric acid units as a structural unit (repeating unit or monomer unit) of the copolymer in a ratio of 1 to 20 mol% with respect to all the structural units. In particular, since the biodegradability can be improved even with a small amount of 3-hydroxybutyric acid unit, the biodegradability and mechanical properties can be highly compatible with each other. Therefore, the 3-hydroxybutyric acid unit is, for example, 2 with respect to all the constituent units. It is about 18 mol%, preferably 3 to 16 mol% (for example, 5 to 10 mol%), and more preferably 5 to 15 mol% (particularly 8 to 12 mol%). Further, in the present invention, the biodegradation rate can be easily adjusted by adjusting the ratio of 3-hydroxybutyric acid units, so that the biodegradation rate can be selected from the range of 1 to 20 mol% depending on the purpose, for example, from the mechanical properties. However, in applications requiring a high degree of biodegradability, the 3-hydroxybutyric acid unit may be, for example, about 10 to 20 mol% (particularly 15 to 20 mol%) with respect to all the constituent units. If the proportion of 3-hydroxybutyric acid units is too low, the biodegradability of the copolymer will decrease, and if it is too high, the mechanical strength of the copolymer will decrease.

In the present invention, the ratio of 3-hydroxybutyric acid units can be measured by ¹ H-NMR spectrum, and in detail, it can be measured by the method described in Examples described later.

At least a part of the 3-hydroxybutyric acid unit may be oligomerized (block polymerization), but it is randomly introduced and polymerized (random polymerization) because it can improve biodegradability and mechanical strength with a small amount. It is preferable to have. That is, since the biodegradable copolymer of the present invention can improve biodegradability even with a small amount of 3-hydroxybutyric acid unit, an oligomer unit (copolymerized oligomer unit) in which both ends of the 3-hydroxybutyric acid unit are bonded to other constituent units. ) May be included. Although such a copolymer oligomer unit is not a homopolymerized oligomer unit in which 3-hydroxybutyric acid units are bonded to each other, it is excellent in biodegradability. Therefore, in the present invention, the proportion of the copolymer oligomer unit is increased. Therefore, the mechanical properties of the biodegradable copolymer can be improved. The molar ratio of the 3-hydroxybutyric acid unit constituting the copolymerized oligomer unit to the 3-hydroxybutyric acid unit constituting the homopolymerized oligomer unit is, for example, the former / the latter = 100/0 to 10/90, preferably 100/0 to 10/90. It is about 100/0 to 50/50, more preferably 100/0 to 70/30 (particularly 100/0 to 80/20), and may be formed only by the copolymerization oligomer unit. If the proportion of the copolymer oligomer unit is too small, the mechanical properties of the copolymer may deteriorate.

The biodegradable copolymer of the present invention may be a curable resin, but a thermoplastic resin is preferable from the viewpoint of excellent biodegradability. Examples of the thermoplastic resin include copolymers containing ester bonds and / or amide bonds, such as copolyesters and copolyamides. Of these, copolyester is preferable because it is excellent in biodegradability.

In copolyester, other structural units include hydroxycarboxylic acid units (other hydroxycarboxylic acid units including lactone units) other than 3-hydroxybutyric acid units, dicarboxylic acid units, and diol units.

(Other hydroxycarboxylic acid units)
Examples of other hydroxycarboxylic acid units include units such as hydroxyalkanoic acid, hydroxycycloalkanecarboxylic acid (hydroxycyclohexanecarboxylic acid and the like), hydroxybenzoic acid (hydroxyarene carboxylic acid and the like) and the like. These hydroxycarboxylic acid units can be used alone or in combination of two or more. Of these hydroxycarboxylic acid units, hydroxyalkanoic acid units are preferable because they are excellent in biodegradability.

Examples of the hydroxyalkanoic acid unit include glycolic acid, 2-hydroxypropanoic acid (lactic acid), 3-hydroxypropanoic acid, 2-hydroxybutanoic acid (2-hydroxybutyric acid), 4-hydroxybutanoic acid, and 3-hydroxy-3. -Methyl-butanoic acid, 2-hydroxypentanoic acid (2-hydroxyvaleric acid), 3-hydroxypentanoic acid, 5-hydroxypentanoic acid, 2-hydroxy-2-methyl-pentanoic acid, 3-hydroxyhexanoic acid, 6- Hydroxyheptanoic acid, 3-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 3-hydroxynanonic acid, 9-hydroxynanonic acid, 3-hydroxydecanoic acid, 10-hydroxydecane Units such as hydroxy C _2-15 alkanoic acid, which may have a C _1-6 alkyl group such as an acid, may be mentioned.

The hydroxyalkanoic acid unit may be the corresponding lactone unit. The lactone unit has a diC _1-12 alkyl group such as β-propiolactone, β-dimethylpropiolactone, γ-butyrolactone, γ-dimethylbutyrolactone, δ-valerolactone, and ε-caprolactone. Units such as C _3-15 lactone may be mentioned.

These hydroxyalkanoic acid units and lactone units can be used alone or in combination of two or more. Of these hydroxyalkanoic acid units, 3-hydroxypropanoic acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, and 3-hydroxyoctanoic acid are biodegradable. , 3-Hydroxynanonic acid, 3-hydroxydecanoic acid and other hydroxy C _3-10 alkanoic acid units (hydroxy C _3-10 alkanoic acid units other than 3-hydroxybutyric acid) or corresponding lactone units are preferred.

(Dicarboxylic acid unit)
Examples of the dicarboxylic acid unit include units such as aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, and aromatic dicarboxylic acid.

Examples of the aliphatic dicarboxylic acid unit include C _1-16 arcandi-carboxylic acids such as alcandicarboxylic acids (eg, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and decandicarboxylic acid). , Etc.), unsaturated aliphatic dicarboxylic acids (eg, C _2-10 alkene-dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, etc.) and the like.

Examples of the alicyclic dicarboxylic acid unit include cycloalcandicarboxylic acid (eg, C _{5-10 cycloalcan} -dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid), di or tricycloalkanodicarboxylic acid (eg, decalin). Dicarboxylic acid, norbornandicarboxylic acid, adamantandicarboxylic acid, tricyclodecanedicarboxylic acid, etc.), cycloalkendicarboxylic acid (eg, C- _{5-10cycloalkene} -dicarboxylic acid such as cyclohexenedicarboxylic acid), di or tricycloalkenedicarboxylic acid (eg, cyclohexenedicarboxylic acid). For example, a unit such as norbornnedicarboxylic acid) can be mentioned.

Examples of the aromatic dicarboxylic acid unit include monocyclic aromatic dicarboxylic acids [eg, phthalic acid, terephthalic acid, isophthalic acid, alkylisophthalic acid (eg, C _1-4 alkylisophthalic acid such as 4-methylisophthalic acid, etc.). C _6-10 allene-dicarboxylic acid, etc.], polycyclic aromatic dicarboxylic acid [eg, fused polycyclic aromatic dicarboxylic acid [eg, naphthalenedicarboxylic acid (eg, 1,5-naphthalenedicarboxylic acid, 1). , 6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, etc. Naphthalenedicarboxylic acid having two carboxyl groups on different rings; 1,2-naphthalene Condensed polycyclic _C10-24 arene-dicarboxylic acid such as dicarboxylic acid, naphthalenedicarboxylic acid having two carboxyl groups on the same ring such as 1,4-naphthalenedicarboxylic acid), anthracendicarboxylic acid, phenanthrangecarboxylic acid, etc. Preferred is a fused polycyclic C _10-16 allene-dicarboxylic acid, more preferably a condensed polycyclic C _10-14 allene-dicarboxylic acid], an arylarene dicarboxylic acid [eg, a biphenyldicarboxylic acid (eg, 2,2'. -C _{6-10aryl-C 6-10 allene} -dicarboxylic acid such as (biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, etc.)], diarylalcandicarboxylic acid [eg, diphenylalcandicarboxylic acid (eg 4,4). DiC _6-10aryl C _1-6 alkane-dicarboxylic acid such as 4'-diphenylmethane dicarboxylic acid], diarylketone dicarboxylic acid [eg, diphenylketone dicarboxylic acid (eg 4.4'-diphenylketone dicarboxylic acid) Etc.), such as diC _{6-10arylketone} -dicarboxylic acid), etc.], dicarboxylic acid having a fluorene skeleton, etc.] and the like.

Further, as the dicarboxylic acid unit having the fluorene skeleton, for example, dicarboxyfluorene (for example, 2,7-dicarboxyfluorene etc.); 9,9-bis (carboxyalkyl) fluorene [for example, 9,9-bis (for example). 2-carboxyethyl) fluorene, 9,9-bis (2-carboxypropyl) fluorene, etc. 9,9-bis (carboxyC _2-6alkyl ) fluorene, etc.]; 9- (carboxy-carboxyalkyl) fluorene [eg, 9- (1-carboxy-2-carboxyethyl) fluorene, 9- (2-carboxy-3-carboxypropyl) fluorene and other 9- (carboxy-carboxyC _2-6 alkyl) fluorene, etc.]; 9,9-bis (Carboxaryl) Fluorene [eg, 9,9-bis (3-carboxyphenyl) fluorene, 9,9-bis (4-carboxyphenyl) fluorene, 9,9-bis (5-carboxy-1-naphthyl) fluorene, 9,9-bis (carboxyC _6-12 aryl) fluorene such as 9,9-bis (6-carboxy-2-naphthyl) fluorene]; 9,9-bis (carboxyalkyl-aryl) fluorene [eg, 9 , 9-bis (4- (carboxymethyl) phenyl) fluorene, 9,9-bis (4- (2-carboxyethyl) phenyl) fluorene, 9,9-bis (3- (carboxymethyl) phenyl) fluorene, 9 , 9-bis (5- (carboxymethyl) -1-naphthyl) fluorene, 9,9-bis (6- (carboxymethyl) -2-naphthyl) fluorene and other 9,9-bis (carboxyC _1-6 alkyl) -C _6-12 aryl) Fluorene, etc.] and other units.

These dicarboxylic acid units can be used alone or in combination of two or more. These dicarboxylic acid units are aliphatic dicarboxylic acid units (C _2-6 alkane-dicarboxylic acid units such as succinic acid and adipic acid) because they can be selected according to the application and biodegradability can be improved. It may be an aromatic dicarboxylic acid unit (particularly, a dicarboxylic acid unit having a fluorene skeleton) from the viewpoint of improving heat resistance and the like.

(Glycol unit)
Examples of the diol unit include an aliphatic diol unit, an alicyclic diol unit, and an aromatic diol unit.

Examples of the aliphatic diol unit include alkanediols (eg, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diores, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, C _2-10 alkanediols such as neopentanediol), polyalkanediols (eg, diethylene glycol, dipropylene glycol, tri). Units such as di or tri-C _2-4 alkanediol such as ethylene glycol) can be mentioned.

Examples of the alicyclic diol unit include cycloalkanediol (for example, C _5-8 cycloalkanediol such as cyclohexanediol) and di (hydroxyalkyl) cycloalkane (for example, cyclohexanedimethanol) for di (hydroxy C _1- ). Units such as _4alkyl ) C _5-8 cycloalkane, etc.) and isosorbide can be mentioned.

Examples of the aromatic diol unit include dihydroxyarene (eg, hydroquinone, resorcinol, etc.) and di (hydroxyalkyl) arene (eg, 1,3-benzenedimethanol, 1,4-benzenedimethanol, etc.) (hydroxy C). _1-4 alkyl) C _6-10 arenes, etc.), bisphenols (eg, biphenol, bis (hydroxyphenyl) C _1-10 alkanes such as bisphenol A, etc.), alkylene oxide adducts of bisphenols, diols having a fluorene skeleton. Units such as.

Further, examples of the diol unit having a fluorene skeleton include a diol compound having a 9,9-bis (hydroxyaryl) fluorene skeleton, for example, a diol unit represented by the following formula (1).

(In the formula, ring Z is an arene ring, R ¹ is an alkylene group, R ² and R ³ are substituents, n is an integer of 0 or 1 or more, k is an integer of 0 to 4, and m is 0 or 1 or more. Is an integer of).

In the above formula (1), examples of the arene ring represented by the ring Z include a monocyclic arene ring such as a benzene ring, a polycyclic arene ring, and the like, and the polycyclic arene ring is a fused polycyclic arene. Rings [eg, fused dicyclic arenes (eg, fused dicyclic C _10-16 arenes such as naphthalene rings), fused two to tetracyclic arene rings, etc.], ring-assembled arene rings [via lane rings (eg, vialane rings, for example). Bi-C _6-12 arene rings such as biphenyl ring and binaphthyl ring)] and the like are included. The two rings Z may be the same or different rings. Preferred arene rings include a benzene ring, a naphthalene ring, a biphenyl ring and the like.

In the above formula (1), examples of the alkylene group R ¹ include a C _2-6 alkylene group such as an ethylene group, a propylene group, a trimethylene group and a 1,2-butanjiyl group. When m is an integer of 2 or more, the types of the alkylene group ^R1 may be the same or different. Further, the types of the alkylene group R ¹ may be the same or different in the same or different ring Z.

The number m of the oxyalkylene group (OR ¹ ) can be selected from the range of, for example, an integer of 0 to 15 (for example, an integer of 0 to 10), for example, an integer of 0 to 8 (for example, 1 to 8). It may be an integer of 0 to 4 (for example, 1 to 4), particularly an integer of about 0 to 3 (for example, 1 to 3), and usually an integer of 0 to 2 (for example, 0 or 1). There may be.

The group [HO- (R ¹ O) _m- ] can be substituted at an appropriate position on the ring Z, for example, when the ring Z is a benzene ring, the 2 to 4-position of the phenyl group (particularly 3-). It is often substituted at the 5-position or 4-position), and when the ring Z is a naphthalene ring, it is often substituted at the 5- to 8-position of the naphthyl group, for example, the 9-position of fluorene. The 1-position or 2-position of the naphthalene ring is substituted with respect to (replaced by the relationship of 1-naphthyl or 2-naphthyl), and the 1,5-position, 2,6-position, etc. are substituted with respect to this substitution position. In many cases, the group [HO- (R ¹ O) _m- ] is replaced due to the above. Further, in the ring-set arene ring Z, the substitution position of the group [HO- (R ¹ O) _m- ] is not particularly limited, and for example, the arene ring bonded to the 9-position of fluorene and / or this arene ring. It may be replaced with an adjacent arene ring. For example, the 3- or 4-position of the biphenyl ring Z may be attached to the 9-position of fluorene, and when the 4-position of the biphenyl ring Z is attached to the 9-position of fluorene, the group [HO] The substitution position of-(R ¹ O) _m- ] may be any of 2-, 3-, 2'-, 3'-, 4'-position, and usually 2-, 3'-, 4 It may be replaced with a'-position, preferably 2-, 4'-position (particularly 2-position).

In the formula (1), examples of the substituent R ² include an alkyl group (for example, a C _1-6 alkyl group such as a methyl group, an ethyl group and a propyl group) and a cycloalkyl group (a cyclohexyl group and the like). C _5-8 cycloalkyl group, etc.), aryl group (eg, C _6-10 aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, etc.), aralkyl group (C _6- such as benzyl group, phenethyl group, etc.) Hydrocarbon groups such as _10aryl -C _1-4 alkyl groups; alkoxy groups (C _1-6 alkoxy groups such as methoxy and ethoxy groups), cycloalkyloxy groups (C _5- such as cyclohexyloxy groups) ₈ cycloalkyloxy group, etc.), aryloxy group (C _6-10 aryloxy group such as phenoxy group), aralkyloxy group (C _6-10 aryl-C _1-4 alkyloxy group such as benzyloxy group); alkylthio Group (such as C _1-8 alkylthio group such as methylthio group); acyl group (such as C _1-6 alkyl-carbonyl group such as acetyl group); alkyloxycarbonyl group (such as C _1-4 alkyloxy- such as methoxycarbonyl group) Halogen group (such as carbonyl group); halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.); nitro group; cyano group; dialkylamino group (eg, diC _1-4 alkylamino group such as dimethylamino group); Examples thereof include a dialkylcarbonylamino group (for example, a diC _1-4 alkyl-carbonylamino group such as a diacetylamino group).

Typical substituents ^R2 include C _1-6 alkyl group (particularly methyl group), C _6-10 aryl group (particularly phenyl group), C _6-8 aryl-C _1-2 alkyl group, and C _1- . ₄ Alkoxy groups and the like can be mentioned. When the substituent R ² is an aryl group, the substituent R ² may form the ring-aggregated arene ring together with the ring Z. The type of substituent ^R2 may be the same or different in the same or different rings Z.

The substitution number n can be appropriately selected depending on the type of ring Z and the like, and may be an integer of about 0 to 8, for example, an integer of 0 to 4, preferably an integer of 0 to 3 (for example, 0 to 2). In particular, it may be 0 or 1. In particular, when n is 1, the ring Z may be a benzene ring, a naphthalene ring or a biphenyl ring, and the substituent ^R2 may be a methyl group.

Examples of the substituent R ³ include a cyano group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), an alkyl group (C _1-6 alkyl group such as a methyl group, an ethyl group, and a propyl group), and an aryl group (. C _6-10 aryl group such as phenyl group) and the like can be mentioned. The substituent R ³ is often an alkyl group (for example, a C _1-4 alkyl group, particularly a C _1-3 alkyl group such as a methyl group). The substitution number k is an integer of 0 to 4 (for example, 0 to 3), preferably an integer of 0 to 2 (for example, 0 or 1), particularly 0. The number of substitutions k may be the same or different from each other, and when k is 2 or more ^, the types of the substituents R3 may be the same or different from each other, and the two benzene rings of the fluorene ring are substituted. The type of substituent ^R3 may be the same or different. The substitution position of the substituent R ³ is not particularly limited, and may be, for example, the 2-position to the 7-position (2-position, 3-position and / or 7-position, etc.) of the fluorene ring.

In the above formula (1), examples of the compound in which m is 0 include 9,9-bis (hydroxyaryl) fluorenes {for example, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3). 9,9-bis (hydroxy C _6-12 ) such as -hydroxyphenyl) fluorene, 9,9-bis (6-hydroxy-2-naphthyl) fluorene, 9,9-bis (5-hydroxy-1-naphthyl) fluorene, etc. 9,9-bis (C _6-12 aryl) such as aryl) fluorene, 9,9-bis (3-phenyl-4-hydroxyphenyl) fluorene, 9,9-bis (4-phenyl-3-hydroxyphenyl) fluorene, etc. -Hydroxy C _6-12aryl ) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, 9,9-bis (4-methyl-3-hydroxyphenyl) fluorene and other 9,9-bis (C _1-4 alkyl-hydroxy C _6-12aryl ) fluorene and the like can be exemplified.

In the formula (1), examples of the compound in which m is 1 include 9,9-bis (hydroxyalkoxyaryl) fluorene {for example, 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9 , 9-bis [4- (2-hydroxypropoxy) phenyl] fluorene, 9,9-bis [6- (2-hydroxyethoxy) -2-naphthyl] fluorene, 9,9-bis [5- (2-hydroxy) Propoxy) -1-naphthyl] fluorene and other 9,9-bis (hydroxy C _2-4 alkoxy C _6-12 aryl) fluorene, 9,9-bis [4-phenyl-3- (2-hydroxyethoxy) phenyl] Fluorene, 9,9-bis [3-phenyl-4- (2-hydroxypropoxy) phenyl] fluorene, etc. 9,9-bis [C _6-12aryl -hydroxy C _2-4 alkoxy C _6-12 aryl] fluorene , 9,9-bis [3-methyl-4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4-methyl-3- (2-hydroxypropoxy) phenyl] fluorene, etc. 9,9- Examples thereof include bis [C _1-4 alkyl-hydroxy C _2-4 alkoxy C _6-12 aryl] fluorene and the like}.

In the formula (1), the compound having m of 2 or more corresponds to the compound having m of 0 or 1, and the repeating unit m of the oxyalkylene group (particularly the oxyC _2-4 alkylene group) is 2 to 5. Examples include compounds.

These diol units can be used alone or in combination of two or more. These diol units can be selected according to the application and can improve biodegradability. Therefore, they are aliphatic diol units [for example, C _2-6 alkane diols such as ethylene glycol and 1,4-butane diol (particularly C ₂ ). _-4 Alkanediol) unit, etc.], and may be an aromatic diol unit (particularly, a diol unit having a fluorene skeleton) from the viewpoint of improving heat resistance and the like.

(Characteristics of copolymer or copolyester)
The copolyester of the present invention is a combination of a 3-hydroxybutyric acid unit and another hydroxycarboxylic acid unit, a combination of a 3-hydroxybutyric acid unit, a dicarboxylic acid unit and a diol unit, a 3-hydroxybutyric acid unit and another hydroxycarboxylic acid. It may be formed by any combination of a unit, a dicarboxylic acid unit and a diol unit. Of these, a combination of a 3-hydroxybutyric acid unit, a dicarboxylic acid unit, and a diol unit is preferable because the properties of the copolymer can be easily controlled and the productivity is also excellent.

The copolymer of the present invention (particularly copolyester) has an aliphatic unit [for example, C _2-10 alkane skeleton (particularly C _2-6 alkane skeleton)) in addition to 3-hydroxybutyric acid unit because it can improve biodegradability. Units having] may be included. The proportion of aliphatic units including 3-hydroxybutyric acid units may be 1 mol% or more, preferably 10 mol% or more, preferably 50 mol% or more, still more preferably 80 mol% or more, based on all the constituent units of the copolymer. It may be% or more (particularly 90 to 100 mol%), and may be only an aliphatic unit (100 mol%) from the viewpoint of improving biodegradability. That is, the copolymer of the present invention (particularly copolyester) may be an aliphatic copolymer (particularly aliphatic copolyester) from the viewpoint of improving biodegradability. If the proportion of aliphatic units is too small, biodegradability may decrease.

Further, the copolymer of the present invention (particularly copolyester) may contain an aromatic unit (particularly a unit having a fluorene skeleton) in order to improve heat resistance, mechanical properties, optical properties and the like, and the aromatic unit may be contained. The ratio of the above may be 0.1 mol% or more with respect to all the constituent units of the copolymer, for example, 1 to 50 mol%, preferably 2 to 30 mol% (for example, 3 to 20 mol%), and more preferably. It may be 4 to 15 mol% (particularly 5 to 10 mol%).

The weight average molecular weight (Mw) of the copolymer (particularly copolyester) may be 1000 or more in terms of polystyrene when measured by gel permeation chromatography (GPC), for example, 2000 to 200,000 (for example, 3000 to 100,000), preferably. May be 4000 to 50,000, more preferably 5000 to 30000 (particularly 6000 to 10000). If the molecular weight is too small, the mechanical properties of the copolymer may deteriorate.

[Manufacturing method of biodegradable copolymer]
The biodegradable copolymer of the present invention is obtained by polymerizing 3-hydroxybutyric acid or a reactive derivative thereof and a mixture of other monomers. In the present invention, 3-hydroxybutyric acid or a reactive derivative thereof may be mixed with other monomers, and it is not necessary to provide a separate step for forming an oligomer unit in which 3-hydroxybutyric acid units are bonded to each other. , A biodegradable copolymer can be produced by a simple method of simply mixing and polymerizing. 3-Hydroxybutyric acid or a reactive derivative thereof and other monomers may be polymerized, for example, by adding both monomers all at once or separately and mixing them.

Examples of the reactive derivative of 3-hydroxybutyric acid include alkyl esters of 3-hydroxybutyric acid (eg, C _1-4 alkyl esters such as methyl ester and ethyl ester), acid halides (eg, acid chloride, acid bromide, etc.) and the like. Can be mentioned.

In the case of producing copolyester, the monomer for forming the hydroxyalkanoic acid unit includes, in addition to hydroxyalkanoic acid, a reactive derivative (ester-forming derivative) thereof. Examples of the reactive derivative include the alkyl ester and the acid halide.

In addition to the dicarboxylic acid, the monomer for forming the dicarboxylic acid unit also includes a reactive derivative thereof. Examples of the reactive derivative include acid anhydrides (succinic anhydride, maleic anhydride and the like saturated or unsaturated aliphatic dicarboxylic acid anhydrides; aromatic dicarboxylic acid anhydrides such as phthalic anhydride and the like), the alkyl esters, and the like. Examples thereof include the acid halide.

The reaction for producing the copolyester may be non-catalyst, and is not limited to a specific catalyst, and a conventional catalyst may be used. Examples of the catalyst include metal catalysts [for example, alkali metals (sodium, etc.), alkaline earth metals (magnesium, calcium, barium, etc.), transition metals (manganese, zinc, cadmium, lead, cobalt, titanium, etc.), periodic table. Group 13 metals (aluminum, etc.), Group 14 metals in the periodic table (germanium, tin, etc.), metal compounds containing Group 15 metals in the periodic table (antimon, etc.)], base catalysts (eg, tertiary amines) (Trialkylamines such as trimethylamine and triethylamine, quaternary ammonium salts (tetraalkylammonium halides such as tetraethylammonium chloride and tetraethylammonium bromide, benzyltrialkylammonium halides such as benzyltrimethylammonium chloride), etc.), acid catalysts [For example, inorganic acids (eg, sulfuric acid, hydrogen chloride (or hydrochloric acid), nitrate, phosphoric acid, etc.), organic acids (eg, sulfonic acid (eg, alkane sulfonic acid such as methane sulfonic acid, ethane sulfonic acid, trifluoromethane sulfonic acid), (Alane sulfonic acid such as p-toluene sulfonic acid)), etc.], etc.] Examples of the metal compound include organic acid salts (acetate, propionate, etc.) and inorganic acid salts (borate, carbonate). , Metal oxides (germanium oxide, etc.), metal chlorides (tin chloride, etc.), metal alkoxides (titaniumtetraalkoxide, titaniumtetra t-butoxide, aluminum isopropoxide, zinc t-butoxide, potassium t-butoxide, etc.) , Alkyl metals (trialkylaluminum, etc.) and the like can be exemplified. These catalysts can be used alone or in combination of two or more.

The amount of the catalyst used is, for example, 0.001 to 1 mol, preferably 0.005 to 0.5 mol, and more preferably 0.01 to 0.1 mol with respect to 100 mol of all the monomers.

The copolyester can be produced by condensation polymerization of the monomer. As the polymerization method (manufacturing method), a conventional method, for example, a melt polymerization method, a solution polymerization method, an interfacial polymerization method, or the like can be used.

The reaction may be carried out in the presence or absence of a solvent, depending on the polymerization method. Examples of the solvent include hydrocarbons (aliphatic hydrocarbons such as hexane, octane and cyclohexane, aromatic hydrocarbons such as toluene), halogenated hydrocarbons (dichloromethane, chloroform, carbon tetrachloride, etc.) and ethers. Classes (cyclic ethers such as dioxane and hydrocarbons), ketones (acetones, methyl ethyl ketones, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), amides (dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, etc.) ), Sulfoxides (dimethylsulfoxide, etc.), cellosolve acetates (C _1-4 alkyl cellosolve acetate such as ethyl cellosolve acetate, etc.) and the like. These solvents can be used alone or in combination of two or more.

The reaction can usually be carried out in an atmosphere of an inert gas (nitrogen, helium, etc.). Further, the reaction may be carried out at room temperature or under reduced pressure, or may be carried out while distilling the generated water or the like out of the reaction system.

The reaction temperature may be, for example, 70 to 250 ° C., preferably 150 to 240 ° C., and more preferably 180 to 230 ° C. The reaction time is not particularly limited, and may be, for example, 30 minutes to 48 hours, usually about 1 to 36 hours.

After completion of the reaction, the copolyester may be separated and purified by a conventional separation method, for example, a method of reprecipitating the reaction product with a poor solvent.

The obtained biodegradable copolymer (particularly copolyester) is not only excellent in biodegradation but also excellent in mechanical properties, so that it is molded by various molding methods (conventional molding methods such as extrusion molding method and injection molding method). You can make a body.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The characteristics and evaluation of the obtained copolymer were measured as follows.

(Molecular weight)
The weight average molecular weight (Mw) was measured in terms of polystyrene by dissolving the sample in chloroform using gel permeation chromatography (“HLC-8320GPC” manufactured by Tosoh Corporation).

(Ratio of 3-hydroxybutyric acid units)
The 3-hydroxybutyric acid unit was dissolved in CDCl ₃ using ¹ H-NMR (“AVANCE III HD 300 MHz” manufactured by Bruker Biospin Co., Ltd.), and the chemical shift change due to esterification near 5.2 ppm was observed. Quantified.

(Biodegradability under aerobic conditions)
For each polyester as a test body, the degradability (decomposition rate) after 28 days was measured under aerobic conditions in accordance with the JIS K 6950 plastic-activated sludge aerobic biodegradability test method.

(Biodegradability under anaerobic conditions)
0.5 g of each polyester as a test piece was added to 40 ml of methane fermented sludge, and the degradability (biogasification rate) after 20 days was measured under high temperature anaerobic conditions of 55 ° C. The processing time of "20 days" is the processing time adopted in a general biogasification plant.

Comparative Example 1 (PBS)
35.4 g (0.30 mol) of succinic acid, 28.4 g (0.32 mol) of 1,4-butanediol and 33 mg of GeO _were placed in a 200 mL flask and heated at 180 ° C. for 1 hour under a nitrogen flow. Then, the temperature was raised to 220 ° C. while gradually reducing the pressure, and the mixture was heated at 220 ° C. for 3 hours to obtain copolyester. The weight average molecular weight Mw of the obtained polyester was 8190.

Example 1 (PBS + 3HB 5%)
35.4 g (0.30 mol) of succinic acid, 28.4 g (0.32 mol) of 1,4-butanediol, 2.98 g (0.11 mol) of (R) -3-hydroxybutyric _acid , 33 mg of GeO It was placed in a 200 mL flask and heated at 180 ° C. for 1 hour under a nitrogen flow. Then, the temperature was raised to 220 ° C. while gradually reducing the pressure, and the mixture was heated at 220 ° C. for 3 hours to obtain copolyester. The weight average molecular weight Mw of the obtained copolyester was 6480. The proportion of the (R) -3-hydroxybutyric acid unit among the constituent units of copolyester was 4.6 mol%.

Example 2 (PBS + 3HB 10%)
Copolyester was obtained in the same manner as in Example 1 except that the blending ratio of (R) -3-hydroxybutyric acid was changed to 5.96 g (0.22 mol). The weight average molecular weight Mw of the obtained copolyester was 5790. The ratio of the (R) -3-hydroxybutyric acid unit to the constituent units of copolyester was 8.7 mol%.

Comparative Example 2 (PBSA)
A commercially available product of PBSA (“Bionore 3020MD” manufactured by Showa Denko KK) was used.

Example 3 (PBSA + 3HB 5%)
The same method as in Example 1 except that a mixture of 17.7 g (0.15 mol) of succinic acid and 21.9 g (0.15 mol) of adipic acid is used instead of 35.4 g (0.30 mol) of succinic acid. Polymerized in. The weight average molecular weight Mw of the obtained copolyester was 6820. The proportion of the (R) -3-hydroxybutyric acid unit among the constituent units of copolyester was 4.6 mol%.

Comparative Example 3 (BPEF)
9,9-Bis [4- (2-hydroxyethoxy) phenyl] fluorene (BPEF, manufactured by Osaka Gas Chemical Co., Ltd.) itself was subjected to a biodegradability test.

Example 4 (PBS + BPEF + 3HB 5%)
Except for using a mixture of 25.6 g (0.28 mol) of 1,4-butanediol and 13.8 g (0.03 mol) of BPEF instead of 28.4 g (0.32 mol) of 1,4-butanediol. The polymerization was carried out in the same manner as in Example 1. The weight average molecular weight Mw of the obtained copolyester was 6460. The proportion of the (R) -3-hydroxybutyric acid unit among the constituent units of copolyester was 4.6 mol%.

The results of biodegradability evaluation of the polyester or BPEF obtained in Examples and Comparative Examples under aerobic and anaerobic conditions are shown in FIGS. 1 and 2, respectively.

As is clear from the results of FIG. 1, in PBS, the decomposition rate was improved by 2.9 times by containing about 5% of 3HB, and the decomposition rate was increased by containing about 10% of 3HB under aerobic conditions. It improved three times. Further, in PBSA, the decomposition rate was improved 8.5 times by containing about 5% of 3HB, and in PBSA + BPEF, the degradability could be imparted to the non-degradable plastic by containing about 5% of 3HB.

On the other hand, as is clear from the results of FIG. 2, under anaerobic conditions, in PBS, the decomposition rate is increased by 1.8 times by containing about 5% of 3HB, and the decomposition rate is 3 by containing about 10% of 3HB. .3 times improved. Further, in PBSA, the decomposition rate was improved 10 times by containing about 5% of 3HB, and in PBSA + BPEF, the degradability could be imparted to the non-degradable plastic by containing about 5% of 3HB.

Since the biodegradable copolymer of the present invention has high biodegradability, it has various fields such as paints, antistatic agents, inks, adhesives, pressure-sensitive agents, electric / electronic materials (for example, carrier transport agents, luminescent materials). , Organic photoconductors, etc.), electrical / electronic parts or equipment (eg, optical lenses, optical films, optical disks, inkjet printers, digital paper, organic semiconductor lasers, dye-sensitized solar cells, etc.), mechanical parts or equipment (eg, dye-sensitized solar cells, etc.) It can be used for automobiles, aviation / space materials, sensors, etc.). In particular, because of its high mechanical properties, it can be easily molded by extrusion molding, injection molding, etc., and molding members (for example, molded bodies such as casings and housings), containers (food, daily necessities, electricity, electronic devices and parts) in various fields. Can be suitably used for containers such as), packaging materials such as films and sheets. In addition, the problem of microplastics, which has become a new problem in recent years, can be solved by taking advantage of its high biodegradability. Since the copolymer contains a skeleton derived from 3HB and has biocompatibility, it can also be used in the medical field (for example, medical equipment).

Claims (10)

A copolyester obtained by reacting 3-hydroxybutyric acid or a reactive derivative thereof with a dicarboxylic acid containing at least an aliphatic dicarboxylic acid or a reactive derivative thereof or a reactive derivative thereof , and a diol containing at least an aliphatic diol. , The biodegradable copolyester contains 3-hydroxybutyric acid unit as a constituent unit at a ratio of 1 to 15 mol% with respect to all the constituent units of copolyester, and the biodegradability under anaerobic conditions is improved. polyester. The biodegradable copolyester according to claim 1, wherein the ratio of 3-hydroxybutyric acid units is 2 to 8.7 mol% with respect to all the constituent units of copolyester. The biodegradable copolyester according to claim 1 or 2, wherein the 3-hydroxybutyric acid unit is randomly introduced. The biodegradable copolyester according to any one of claims 1 to 3, wherein both ends of the 3-hydroxybutyric acid unit contain an oligomer unit bonded to a dicarboxylic acid unit and a diol unit. The biodegradable copolyester according to any one of claims 1 to 4, wherein the 3-hydroxybutyric acid is (R) -3-hydroxybutyric acid. The biodegradable copolyester according to any one of claims 1 to 5, which is a thermoplastic resin. The biodegradable copolyester according to any one of claims 1 to 6, wherein the dicarboxylic acid unit and the diol unit have at least a C _2-10 alkane skeleton. The biodegradable copolyester according to any one of claims 1 to 7, further comprising a unit having a fluorene skeleton. Claims 1 to 8 for polymerizing a mixture of 3-hydroxybutyric acid or a reactive derivative thereof, at least a dicarboxylic acid containing an aliphatic dicarboxylic acid or a reactive derivative thereof or a reactive derivative thereof, and a diol containing at least an aliphatic diol. The method for producing a biodegradable copolyester according to any one of the above. A method for improving the biodegradability of copolyester obtained by reacting at least a dicarboxylic acid containing an aliphatic dicarboxylic acid or a reactive derivative thereof or a reactive derivative thereof with a diol containing at least an aliphatic diol under anaerobic conditions. There is a method of introducing 3-hydroxybutyric acid units into the copolyester at a ratio of 1 to 15 mol% with respect to all the constituent units.

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