Ethylenically unsaturated compounds and their uses

Abstract

To provide a novel ethylenically unsaturated compound that allows the preparation of a high-molecular-weight resin while having a 3HB-derived skeleton, and a resin (polymer) containing a constitutional unit derived from the ethylenically unsaturated compound, and methods for producing the same and applications therefor.SOLUTION: The present invention discloses a compound represented by formula (1), which may be an R form (1R) thereof (where R1 is a hydrogen atom or an alkyl group). A thermoplastic resin according to the present invention includes a constitutional unit of formula (4). The constitutional unit of formula (4) may include an R form (4R) thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel ethylenically unsaturated compound having a skeleton derived from 3-hydroxybutyric acid (also known as 3HB), a resin (polymer) containing structural units derived from this ethylenically unsaturated compound, and methods for producing and using these. [Background technology]

[0002] From the perspective of environmental conservation and the realization of a sustainable society, efforts are being made to convert some or all of plastic raw materials into biomass, and the use of bio-based or biodegradable plastics is increasing. Although plastic is an essential material in human life, once released into the environment, it drifts in the ocean and is broken down and fragmented by ultraviolet rays, producing microplastics with diameters of 5 mm or less. There are concerns that these microplastics may cause endocrine disruption if ingested by the living organisms of birds, fish, and other animals.

[0003] In recent years, efforts have been made to address the microplastic problem by, for example, imparting biodegradability to garbage bags. Examples of biodegradable plastics include polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), and polycaprolactone (PCL). However, these biodegradable plastics have low biodegradability under anaerobic conditions (or are difficult to biogasify), resulting in low biodegradability in the ocean. Because these biodegradable plastics are highly dense and sink in water (such as the ocean), solving the microplastic problem requires the development of plastics that are highly biodegradable even under anaerobic conditions, such as the ocean (or that do not remain in the ocean as microplastics).

[0004] H. Yagi et al., Polymer Degradation and Stability, 110, (2014), 278-283 (Non-Patent Document 1) evaluated the biodegradability of various biodegradable polyesters under anaerobic conditions and disclosed that poly-3-hydroxybutyrate (PHB) exhibits higher biodegradability under anaerobic conditions than PLA, PCL, and PBS. However, poly-3-hydroxyalkanoates such as PHB, which are produced (biosynthesized) by microorganisms, lack the mechanical properties required for general-purpose plastic molded bodies and are also economically unviable, and therefore have not been widely used.

[0005] Meanwhile, Japanese Patent Laid-Open Publication No. 2017-025138 (Patent Document 1) discloses a biodegradable copolymer in which the proportion of 3-hydroxybutyric acid (3HB) units is 1 to 20 mol% relative to all constituent units, as a biodegradable plastic into which 3HB has been introduced by chemical synthesis. Patent Document 1 describes that biodegradable copolymers in which 3HB units have been randomly introduced have high biodegradability under aerobic and anaerobic conditions, and that the biodegradation rate can be controlled by changing the proportion of 3HB units in the copolymer.

[0006] Nihed Ben Halima, RSC Adv., 6, 2016, 39823-39832 (Non-Patent Document 2) describes that highly biocompatible polyvinyl alcohol (PVA) is biodegradable under both aerobic and anaerobic conditions. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-025138 [Non-patent literature]

[0008] [Non-Patent Document 1] H.Yagi et al., Polymer Degradation and Stability, 110, (2014), 278-283(Table 1) [Non-patent document 2] Nihed Ben Halima, RSC Adv., 6, 2016, 39823-39832 Summary of the Invention [Problem to be solved by the invention]

[0009] In the examples of Patent Document 1, it is described that a copolyester containing 3HB units at a ratio of 4.6 or 8.7 mol % was prepared by adding monomers that form PBS, PBSA, etc., and (R)-3HB all at once and polymerizing them, and that the weight average molecular weight Mw was 5790 to 6820.

[0010] However, 3-hydroxyalkanoic acids (3HA) such as 3HB have a highly reactive carboxyl group and a less reactive secondary alcohol hydroxyl group. Therefore, when preparing a resin using 3HA as a polymerization component (resin raw material or monomer), not only is the polymerization reaction difficult to proceed due to the secondary alcohol, but intramolecular dehydration occurs between the hydrogen atom at the α-position of the carboxyl group and the hydroxyl group (secondary alcohol) at the β-position due to heating or acid, making it susceptible to decomposition into unsaturated monocarboxylic acids such as crotonic acid, making it difficult to synthesize high-molecular-weight polymers containing 3HA units.

[0011] Therefore, the biodegradable copolymer described in Patent Document 1 is difficult to produce because the monomer has low reactivity and is easily decomposed. Even if it can be produced, it is difficult to increase the molecular weight, and the resin properties may be insufficient, which may limit its applications.

[0012] Furthermore, as shown in Non-Patent Document 2, PVA is highly biocompatible and biodegradable, but its applications are limited because it is a water-soluble polymer, and in order to control its water solubility, it is necessary to adjust the degree of saponification or perform crosslinking.

[0013] Therefore, an object of the present invention is to provide a novel ethylenically unsaturated compound that can be used to prepare a high molecular weight resin even though it has a skeleton derived from 3HB, a resin (polymer) containing structural units derived from this ethylenically unsaturated compound, and methods for producing the same and uses thereof.

[0014] Another object of the present invention is to provide an ethylenically unsaturated compound from which a resin can be prepared that is water-insoluble during use but is biodegradable under anaerobic conditions such as in water (e.g., in the ocean) after use; a resin (polymer) containing structural units derived from this ethylenically unsaturated compound; and methods for producing the same and uses thereof. [Means for solving the problem]

[0015] Therefore, the present inventors conducted extensive research to solve the above-mentioned problems, and as a result, they found that a specific ethylenically unsaturated compound having a 3HB skeleton can be easily made to have a high molecular weight, despite having a 3HB skeleton, and thus completed the present invention.

[0016] That is, the ethylenically unsaturated compound of the present invention is represented by the following formula (1): The compound represented by the formula (1) may be a compound represented by the following formula (1R) (R configuration or R form).

[0017] [ka]

[0018] (In the formula, R 1 indicates a hydrogen atom or an alkyl group).

[0019] In the formula (1), R 1 is a hydrogen atom or C 1-4 It may be an alkyl group.

[0020] The present invention includes a method for producing the compound represented by formula (1) by reacting 3-hydroxybutyric acid represented by formula (2) below with a compound represented by formula (3) below.

[0021] [ka]

[0022] (In the formula, R 2 represents a hydrogen atom or an alkyl group, and R 1 is the same as the above formula (1).

[0023] The present invention also encompasses a thermoplastic resin containing a structural unit represented by the following formula (4): The structural unit represented by formula (4) may contain a structural unit represented by the following formula (4R):

[0024] [ka]

[0025] (In the formula, R 1 is the same as the above formula (1).

[0026] The proportion of the structural units represented by formula (4) may be about 5 to 100 mol % relative to all structural units of the thermoplastic resin. The weight average molecular weight Mw of the thermoplastic resin may be about 5,000 to 2,000,000. The thermoplastic resin may be a water-insoluble resin. The thermoplastic resin may be a biodegradable resin. The thermoplastic resin may have a biogasification rate of about 2% or more after 7 days under anaerobic conditions.

[0027] The present invention relates to a polymerizable composition comprising a step of polymerizing a polymerization component containing a compound represented by formula (1); The present invention also encompasses a method for producing the thermoplastic resin, which includes at least one step selected from the group consisting of a step of reacting a polymer containing the compound represented by formula (3) as a polymerization component or a saponified product thereof with 3-hydroxybutyric acid represented by formula (2).

[0028] The present invention also encompasses a method for improving (or imparting) biodegradability to a thermoplastic resin by introducing a constitutional unit represented by the above formula (4) into the thermoplastic resin.

[0029] Furthermore, the present invention also encompasses a method for decomposing the thermoplastic resin by exposing the thermoplastic resin to aerobic or anaerobic conditions, in which the thermoplastic resin may be immersed in water (e.g., in the ocean) or buried in soil, particularly under anaerobic conditions.

[0030] The present invention also includes a molded article containing the thermoplastic resin.

[0031] In this specification and claims, unless otherwise specified, a skeleton derived from 3-hydroxybutyric acid (or 3HB skeleton) means a chemical structure (or monovalent group) represented by the following formula in which OH (hydroxyl group) is removed from the carboxyl group of 3HB.

[0032] [ka] [Effects of the Invention]

[0033] By using the specific ethylenically unsaturated compound represented by formula (1) of the present invention as a polymerization component, a high molecular weight resin can be prepared, even if it has a skeleton derived from 3HB. Furthermore, resins containing the structural unit represented by formula (4) can be used in applications requiring water insolubility (water resistance or hot water resistance) (even if they are water insolubility during use), and after use, the 3HB skeleton can be biodegraded relatively quickly under anaerobic conditions, such as in water (e.g., in the ocean). Furthermore, because the resin can be primarily composed of a chemical structure that exhibits biodegradability, it can be a resin that does not become microplastics in the ocean or other environments. DETAILED DESCRIPTION OF THE INVENTION

[0034] [Compound represented by formula (1) and its production method] The ethylenically unsaturated compound having a 3HB skeleton of the present invention is represented by the following formula (1).

[0035] [ka]

[0036] (In the formula, R 1 indicates a hydrogen atom or an alkyl group).

[0037] In the formula (1), R 1 The alkyl group represented by the formula (I) is, for example, a C methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, etc. 1-12 The alkyl group may be an alkyl group. Preferred alkyl groups are as follows, in order of decreasing order: 1-8 Alkyl group, C 1-6 Alkyl group, C 1-4 Alkyl group, C 1-2 It is preferably an alkyl group, more preferably a methyl group.

[0038] Preferred R 1 is a hydrogen atom or C 1-4 is an alkyl group, more preferably a hydrogen atom or C 1-2 The alkyl group is an alkyl group (such as a hydrogen atom or a methyl group), and a hydrogen atom is particularly preferred in terms of improving biodegradability.

[0039] In the formula (1), the configuration of the 3HB skeleton (configuration at the asymmetric carbon atom) may be either the R configuration (R-form) or the S configuration (S-form), but from the viewpoint of improving biodegradability, the R configuration (R-form) is preferred. That is, the compound represented by the formula (1) is preferably a compound (R-form) represented by the following formula (1R):

[0040] [ka]

[0041] (In the formula, R 1 is the same as the above formula (1), including preferred embodiments.

[0042] (Method for producing the compound represented by formula (1)) The method for producing the compound represented by formula (1) is not particularly limited, but a representative method includes reacting (transesterification) 3-hydroxybutyric acid (3HB) represented by the following formula (2) with a compound represented by the following formula (3) (carboxylic acid alkenyl ester).

[0043] [ka]

[0044] (In the formula, R 2 represents a hydrogen atom or an alkyl group, and R 1 is the same as the above formula (1).

[0045] The 3HB represented by formula (2) may be an optical isomer (R- or S-isomer) or a racemate. However, from the viewpoint of biodegradability, it preferably contains at least the R-isomer ((R)-3-hydroxybutyric acid). The proportion of the R-isomer in 3HB, i.e., the optical purity (enantiomer or optical isomer excess), is, for example, about 50% ee or more (e.g., 80% ee or more), preferably 90% ee or more (e.g., 95 to 100% ee), and more preferably 98 to 100% ee (e.g., 99 to 100% ee, particularly essentially 100% ee). If the optical purity is too low, biodegradability may be reduced. The 3HB represented by formula (2) may be a commercially available product, or may be derived from biomass raw materials (biological resources).

[0046] In the formula (3), R 2 Examples of the alkyl group represented by the formula (I) include C methyl group, ethyl group, propyl group, isopropyl group, and butyl group. 1-12 It may also be an alkyl group. 2 The following steps are taken: 1-8 Alkyl group, C 1-4 Alkyl group, C 1-2 It is preferably an alkyl group, more preferably a methyl group.

[0047] Examples of the compound (alkenyl ester) represented by the formula (3) include C vinyl formate, vinyl acetate, isopropenyl acetate, vinyl propionate, and isopropenyl propionate. 1-4 Alkanoic acid C 2-4 Alkenyl esters and the like are preferred. 2-3 Alkanoic acid C 2-3 Alkenyl esters are exemplified, and vinyl acetate is more preferred.

[0048] The compound represented by formula (3) may be a commercially available product or may be synthesized by a conventional method. In particular, vinyl acetate is generally synthesized by the ethylene method, which involves reacting ethylene, oxygen (or air), and acetic acid. However, since ethylene is widely present in nature (e.g., in plants as a plant hormone), and acetic acid can also be produced using acetic acid bacteria, it can also be synthesized from biomass raw materials (biological resources). Furthermore, since biomass raw materials can also be used for 3HB represented by formula (2), the compound represented by formula (1) obtained by reacting these can be synthesized without using petroleum-derived raw materials, thereby effectively reducing the environmental impact.

[0049] The proportion of the compound represented by the formula (3) may be, for example, about 1 to 20 moles, preferably about 5 to 15 moles, and more preferably about 8 to 12 moles relative to 1 mole of 3HB represented by the formula (2).

[0050] The reaction may be carried out in the presence of a conventional transesterification catalyst. The transesterification catalyst is not particularly limited and may be a mercury compound (e.g., mercury acetate, mercury sulfate, etc.) or a ruthenium compound, but a palladium compound is preferred from the viewpoint of safety. Examples of palladium compounds include palladium carboxylates (e.g., palladium acetate, palladium propionate, palladium pivalate, etc.), palladium halides (e.g., palladium chloride, palladium bromide, etc.), palladium nitrate, and palladium complexes.

[0051] These catalysts can be used alone or in combination. Among these catalysts, palladium carboxylates such as palladium acetate are preferred. The proportion of the catalyst (main catalyst) may be, for example, about 0.0001 to 0.1 mol, preferably about 0.001 to 0.02 mol, and more preferably about 0.003 to 0.01 mol per 1 mol of 3HB represented by the formula (2).

[0052] The reaction may be carried out in the presence of a co-catalyst together with a transesterification catalyst (main catalyst), if necessary, or without a co-catalyst. Examples of the co-catalyst include alkali metal compounds [e.g., alkali metal carbonates (lithium carbonate, etc.), alkali metal hydrogen carbonates (e.g., lithium hydrogen carbonate, sodium hydrogen carbonate, etc.), alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal halides (lithium chloride, sodium chloride, potassium chloride, lithium bromide, sodium bromide, potassium bromide, lithium iodide, sodium iodide, potassium iodide, etc.), alkali metal carboxylates (lithium acetate, sodium acetate, potassium acetate, lithium propionate, etc.]. 1-20 carboxylates, etc.), alkali metal phosphates (lithium triphosphate, sodium triphosphate, lithium diphosphate, sodium diphosphate, etc.), alkali metal nitrates (lithium nitrate, sodium nitrate, potassium nitrate, etc.), alkali metal nitrites (lithium nitrite, sodium nitrite, potassium nitrite, etc.), alkaline earth metal compounds (e.g., alkaline earth metal carbonates such as magnesium carbonate, alkaline earth metal bicarbonates such as magnesium bicarbonate, alkaline earth metal hydroxides such as magnesium hydroxide, alkaline earth metal carboxylates such as magnesium acetate, etc.), copper compounds (copper halides such as copper bromide, copper carboxylates such as copper acetate, etc.), alkyl nitrite esters (nitrous acid C such as propyl nitrite, etc.) 1-10 alkyl esters, etc.

[0053] These co-catalysts can be used alone or in combination of two or more. Among these co-catalysts, alkali metal hydroxides such as potassium hydroxide are preferred, from the viewpoints that the reaction can proceed easily or efficiently even at room temperature, possibly due to their buffering action, and that decomposition of the compound represented by formula (1) can be suppressed.

[0054] When a co-catalyst (particularly an alkali metal hydroxide such as potassium hydroxide) is used, the proportion thereof may be, for example, 0.1 to 10 mol (e.g., 1 to 8 mol), preferably 1.5 to 7 mol (e.g., 2 to 6 mol), and more preferably 2.5 to 5 mol (e.g., 3 to 4 mol), relative to 1 mol of the catalyst (main catalyst).

[0055] The reaction may be carried out in the presence of a transesterification catalyst and, if necessary, a redox agent, such as iron compounds including iron chloride, iron bromide, iron sulfate, and iron nitrate.

[0056] The reaction may be carried out in an atmosphere of an inert gas (e.g., nitrogen gas; a rare gas such as helium gas or argon gas) or in air, with an inert gas atmosphere such as argon gas being preferred. The reaction temperature may be, for example, 20 to 150°C, preferably 30 to 100°C (e.g., 40 to 80°C), and more preferably about 50 to 70°C. When a cocatalyst (particularly an alkali metal hydroxide such as potassium hydroxide) is used, the reaction temperature may be about room temperature, for example, 10 to 40°C, and preferably about 20 to 30°C. If the reaction temperature is too high, the compound represented by formula (1) may be decomposed. The reaction time is not particularly limited and may be, for example, about 1 to 48 hours, preferably about 12 to 36 hours, and more preferably about 16 to 24 hours.

[0057] After the reaction is complete, the product can be separated and purified by a conventional separation method, such as neutralization, filtration, concentration, drying, extraction, crystallization, recrystallization, reprecipitation, column chromatography, distillation (e.g., reduced pressure distillation), or a combination thereof. Since the compound represented by formula (1) is easily decomposed by heat, it may be stored in a low-temperature environment (e.g., refrigerated, particularly frozen).

[0058] The compound represented by formula (1) may be an optical isomer (R or S isomer) or a racemate, but from the viewpoint of biodegradability, it preferably contains at least the R isomer ((R)-3HB). The proportion of the R isomer in the compound represented by formula (1), i.e., the optical purity (or enantiomeric excess), is, for example, about 50% ee or more (e.g., 80% ee or more), preferably 90% ee or more (e.g., 95 to 100% ee), and more preferably 98 to 100% ee (e.g., 99 to 100% ee, particularly substantially 100% ee). If the optical purity is too low, biodegradability may be reduced.

[0059] [Thermoplastic resin containing a structural unit represented by formula (4)] The ethylenically unsaturated compound represented by formula (1) can be used as a polymerization component (monomer) for forming a polymer (thermoplastic resin or chain or linear polymer) containing a structural unit having a 3HB skeleton. By using the compound represented by formula (1) as a polymerization component, it is possible to easily and efficiently prepare a thermoplastic resin with a relatively high molecular weight while effectively suppressing decomposition of 3HB. That is, the thermoplastic resin of the present invention contains at least a structural unit represented by formula (4) below.

[0060] [ka]

[0061] (In the formula, R 1 is the same as the above formula (1), including preferred embodiments.

[0062] From the viewpoint of improving biodegradability, the constitutional unit represented by the formula (4) preferably contains at least a constitutional unit represented by the following formula (4R) (i.e., a constitutional unit derived from the R-configuration of the compound represented by the formula (1)):

[0063] [ka]

[0064] (In the formula, R 1 is the same as the above formula (1), including preferred embodiments.

[0065] The proportion of the structural units represented by the formula (4) may be selected, for example, from a range of about 10 to 100 mol % relative to all structural units (units derived from polymerization components) of the thermoplastic resin, and may be preferably 50 to 100 mol % (e.g., 70 to 100 mol %), more preferably 80 to 100 mol % (e.g., 90 to 100 mol %), and particularly 95 to 100 mol % (e.g., 98 to 100 mol %, or substantially 100 mol % (homopolymer)).

[0066] Furthermore, the proportion of the structural units represented by the formula (4R) may be selected from a range of, for example, about 5 to 100 mol% (e.g., 10 to 100 mol%) relative to all structural units represented by the formula (4), and from the viewpoint of improving biodegradability, it may be preferably 50 to 100 mol% (e.g., 70 to 100 mol%), more preferably 80 to 100 mol% (e.g., 90 to 100 mol%), and particularly 95 to 100 mol% (e.g., 98 to 100 mol%, or essentially 100 mol%).

[0067] If the proportion of the constitutional unit represented by the formula (4) (particularly (4R)) is too low, biodegradability may decrease.

[0068] (copolymerization unit) The thermoplastic resin of the present invention may be a homopolymer of the structural unit represented by the formula (4) (particularly (4R)), or may be a copolymer further containing, as a copolymerization unit, a structural unit other than the formula (4). The copolymer may be a random copolymer, a block copolymer, an alternating copolymer, or the like, with a random copolymer being preferred.

[0069] The copolymerization unit is not particularly limited, and may be, for example, a structural unit derived from a compound having an ethylenically unsaturated bond [for example, a conventional polymerizable compound having an alkenyl group such as a vinyl group, an allyl group, or an isopropenyl group, or a (meth)acryloyl group]. A representative copolymerization unit (other structural unit) may be a structural unit represented by the following formula (5).

[0070] [ka]

[0071] [In the formula, R 3 represents a hydrogen atom or an alkyl group, and R 4 is a hydrogen atom or a group [-C(=O)-A 1 -R 4a ](In the formula, A 1 represents a linear or branched alkylene group (or alkylidene group), and R 4a represents a hydrogen atom or a hydroxyl group.

[0072] In the formula (5), R 3 The alkyl group represented by the formula (I) is, for example, a C methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, etc. 1-12 The alkyl group may be an alkyl group. Preferred alkyl groups are as follows, in order of decreasing order: 1-8 Alkyl group, C 1-6 Alkyl group, C 1-4 Alkyl group, C 1-2 It is preferably an alkyl group, more preferably a methyl group.

[0073] Preferred R 3is a hydrogen atom or C 1-4 is an alkyl group, more preferably a hydrogen atom or C 1-2 The alkyl group is an alkyl group (such as a hydrogen atom or a methyl group), and a hydrogen atom is particularly preferred from the viewpoint of improving biodegradability and water solubility after decomposition.

[0074] R 4 A group represented by [-C(=O)-A 1 -R 4a ], A 1 Examples of the linear or branched alkylene group (or alkylidene group) represented by the formula (I) include C groups such as a methylene group (or methylidene group), an ethylene group, an ethylidene group, an n-propylene group, an isopropylene group, an n-butylene group, and an isobutylene group. 1-12 An alkylene group (or an alkylidene group) is preferred. 1 The following steps are taken: 1-8 Alkylene group (or alkylidene group), C 1-6 Alkylene group (or alkylidene group), C 1-4 It may be an alkylene group (or alkylidene group).

[0075] R 4 A group represented by [-C(=O)-A 1 -R 4a ], R 4a Examples of the acyl group (or alkanoyl group) in which is a hydrogen atom include C groups such as an acetyl group and a propionyl group. 2-12 Preferred acyl groups include the following in the order listed below: 2-8 Acyl group, C 2-6 Acyl group, C 2-4 Acyl group, C 2-3 It is preferably an acyl group, more preferably an acetyl group.

[0076] R 4 A group represented by [-C(=O)-A 1 -R 4a ], R 4aExamples of the hydroxyacyl group (or hydroxyalkylcarbonyl group) in which is a hydroxyl group include a glycoloyl group (a hydroxyacetyl group or a hydroxymethylcarbonyl group), a lactoyl group [a 2-hydroxypropionyl group or a (1-hydroxyethyl)carbonyl group], a 3-hydroxypropionyl group [or a (2-hydroxyethyl)carbonyl group], a 2-hydroxybutyryl group, a 4-hydroxybutyryl group, a 2-hydroxyvaleryl group, a 2-hydroxy-3-methylbutyryl group, a 3-hydroxyvaleryl group, and a 3-hydroxy-2-methylbutyryl group. , 3-hydroxy-3-methylbutyryl group, 5-hydroxyvaleryl group, 2-hydroxyhexanoyl group, 2-hydroxy-2-methyl-valeryl group, 2-hydroxy-4-methyl-valeryl group, 3-hydroxyhexanoyl group, 3-hydroxy-3-methyl-valeryl group, 6-hydroxyhexanoyl group, 3-hydroxyheptanoyl group, 7-hydroxyheptanoyl group, 3-hydroxyoctanoyl group, 8-hydroxyoctanoyl group, 3-hydroxynonanoyl group, 9-hydroxynonanoyl group, 3-hydroxydecanoyl group, 10-hydroxydecanoyl group, etc. 1-6 Hydroxy C optionally having an alkyl group 2-15 alkanoyl groups, etc. (excluding 3-hydroxybutyryl groups [or (2-hydroxypropyl)carbonyl groups]). Preferred hydroxyacyl groups include lactoyl groups, C 1-4 3-hydroxy C optionally containing an alkyl group 3-12 Examples include an alkanoyl group.

[0077] The structural unit represented by the formula (5) may be introduced into the thermoplastic resin by copolymerizing a compound having a corresponding ethylenically unsaturated bond, or may be converted from a different structural unit by a chemical reaction.

[0078] In addition, in the formula (5), R 4 is the group [-C(=O)-A 1 -R 4a In the case of a structural unit having a structure of R4a is a hydrogen atom (R 4a is an acyl group), for example, vinyl acetate, isopropenyl acetate, vinyl propionate, etc. 2-12 Alkanoic acid C 2-6 Alkenyl, preferably C such as vinyl acetate 2-6 Alkanoic acid C 2-3 Alkenyl may also be used as a copolymerization component; R 4a is a hydroxyl group (R 4a is a hydroxyacyl group), for example, hydroxyalkanoic acids corresponding to the examples of the hydroxyacyl group, i.e., glycolic acid, 2-hydroxypropanoic acid (or lactic acid), 3-hydroxypropanoic acid, 2-hydroxybutanoic acid (or 2-hydroxybutyric acid), 4-hydroxybutanoic acid, 2-hydroxypentanoic acid (2-hydroxyvaleric acid), 2-hydroxy-3-methyl-butanoic acid, 3-hydroxypentanoic acid, 3-hydroxy-2-methyl-butanoic acid, 3-hydroxy-3-methyl -butanoic acid, 5-hydroxypentanoic acid, 2-hydroxyhexanoic acid, 2-hydroxy-2-methyl-pentanoic acid, 2-hydroxy-4-methyl-pentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxy-3-methyl-pentanoic acid, 6-hydroxyheptanoic acid, 3-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 9-hydroxynonanoic acid, 3-hydroxydecanoic acid, 10-hydroxydecanoic acid, etc. 1-6 Hydroxy C optionally having an alkyl group 2-15 Alkanoic acid (preferably lactic acid), or 3-hydroxyalkanoic acid (e.g., C 1-4 3-hydroxy C optionally containing an alkyl group 3-12 A compound having an ethylenically unsaturated bond obtained by transesterification of an alkanoic acid, etc. (excluding 3HB), with a compound represented by the formula (3) (alkenyl carboxylic acid ester) may also be used as a copolymerization component.

[0079] In addition, the hydroxyalkanoic acid (or R 4When ) has an asymmetric carbon atom, the configuration may be either the R configuration (R form) or the S configuration (S form), but from the viewpoint of improving biodegradability, the R configuration (R form) is preferred.

[0080] These structural units represented by the formula (5) may be contained alone or in combination of two or more kinds. 3 is a hydrogen atom or a methyl group (preferably a hydrogen atom), R 4 is a hydrogen atom or a group [-C(=O)-A 1 -R 4a ](In the formula, A 1 is a linear or branched alkylene group (or alkylidene group), R 4a represents a hydroxyl group.) is preferred. From the viewpoint of procurement (ease of procurement or reduction of environmental load), 3 is a hydrogen atom or a methyl group (preferably a hydrogen atom), R 4 is the group [-C(=O)-A 1 -R 4a ](In the formula, A 1 is a linear or branched alkylene group (or alkylidene group), R 4a represents a hydrogen atom.) is preferred.

[0081] The thermoplastic resin may or may not contain copolymer units other than the copolymer units represented by the formula (5). From the viewpoint of improving biodegradability, the copolymer units represented by the formula (5) are preferred.

[0082] The proportion (total proportion) of copolymerization units may be selected from the range of, for example, about 0 to 99 mol% (e.g., 0 to 90 mol%) relative to all structural units of the thermoplastic resin, and may be preferably about 70 mol% or less (e.g., 10 to 60 mol%), and more preferably about 50 mol% or less (e.g., 20 to 30 mol%). Depending on the application, the proportion (total proportion) of copolymerization units may be, for example, about 30 to 99 mol% (e.g., 50 to 97 mol%), and preferably about 70 to 95 mol% (e.g., 80 to 93 mol%) relative to all structural units of the thermoplastic resin. If the proportion of copolymerization units is too high, biodegradability may decrease, and conversely, if it is too low, a copolymer may not be obtained efficiently.

[0083] In addition, when the thermoplastic resin contains copolymerization units, the ratio of the structural units represented by the formula (5) [particularly, R 3 is a hydrogen atom or a methyl group (preferably a hydrogen atom), R 4 is a hydrogen atom or a group [-C(=O)-A 1 -R 4a ](In the formula, A 1 is a linear or branched alkylene group (or alkylidene group), R 4a represents a hydroxyl group.) may be selected, for example, from a range of about 0 to 100 mol % (e.g., 10 to 100 mol %) relative to the total copolymerization units, and may be preferably 50 mol % or more (70 to 100 mol %), more preferably 80 mol % or more (90 to 100 mol %), and particularly 95 mol % or more (e.g., substantially 100 mol %, i.e., the copolymerization units are only the structural units represented by formula (5)). If the proportion of the structural units represented by formula (5) in the copolymerization units is too low, biodegradability may be reduced.

[0084] (Method of manufacturing thermoplastic resin) The method for producing the thermoplastic resin is not particularly limited, and the thermoplastic resin may be prepared, for example, by a production method including at least one step selected from the group consisting of a step of polymerizing a polymerization component containing the compound represented by formula (1) (polymerization step) and a step of reacting 3HB with a side chain of a polymer by a polymer reaction (3HB side chain introduction step).

[0085] Polymerization process The polymerization method is not particularly limited as long as it can polymerize the compound represented by formula (1) and, if necessary, a compound having an ethylenically unsaturated bond for introducing a copolymerization unit such as a unit represented by formula (5), and may be, for example, radical polymerization, ionic polymerization (anionic polymerization, etc.), coordination polymerization, etc., with radical polymerization being preferred. Radical polymerization may be bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., with solution polymerization or suspension polymerization being preferred, with suspension polymerization being more preferred in that it is easy to adjust the molecular weight distribution to a narrow value (low Mw / Mn), and solution polymerization being more preferred in that it is easy to adjust the Mw to a large value.

[0086] The radical polymerization may be carried out in the presence or absence of a polymerization initiator, which may be a polymerization initiator capable of generating radicals by heat and / or light.

[0087] Examples of the thermal polymerization initiator include organic peroxides and azo compounds. Examples of the organic peroxides include dialkyl peroxides such as di-t-butyl peroxide; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; peracids (or peresters) such as t-butyl hydroperoxide, cumene hydroperoxide, and t-butyl peracetate; ketone peroxides; peroxycarbonates; and peroxyketals. Examples of the azo compounds include azonitrile compounds such as 2,2'-azobis(isobutyronitrile), azoamide compounds, and azoamidine compounds.

[0088] Examples of photopolymerization initiators include benzoins, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones, etc. The photopolymerization initiators may be combined with conventional photosensitizers such as tertiary amines, and the photosensitizers may be used alone or in combination of two or more.

[0089] The polymerization initiator may be an oil-soluble polymerization initiator, but a water-soluble polymerization initiator may also be used depending on the polymerization method, etc., and for example, peroxides such as hydrogen peroxide, persulfates (e.g., potassium persulfate, ammonium persulfate (APS or ammonium peroxodisulfate)), aqueous azo compounds, redox polymerization initiators, etc. may also be used.

[0090] These polymerization initiators can be used alone or in combination of two or more. Among these polymerization initiators, thermal polymerization initiators are preferred, and among these, water-soluble polymerization initiators such as APS are preferred.

[0091] The ratio of the polymerization initiator may be appropriately selected depending on the application, etc., and may be, for example, 0.01 × 10 -3 ~50×10 -3 moles (e.g., 0.05 x 10 -3 ~10×10 -3 mol), preferably 0.1 × 10 -3 ~5×10 -3 moles (e.g., 0.5 × 10 -3 ~3×10 -3 mole, specifically 0.5 x 10 -3 ~1×10 -3 It may be on the order of 1 mole.

[0092] In the radical polymerization, a chain transfer agent, such as an organic peroxide, an organic azo compound, a halogenated hydrocarbon (carbon tetrachloride, etc.), a mercaptan, or a thiol, which is soluble in the polymerization components, may be used to adjust the molecular weight of the thermoplastic resin. The amount of the chain transfer agent used may be, for example, 5% by mass or less based on the thermoplastic resin.

[0093] The radical polymerization may be carried out in the presence or absence of a solvent (or dispersion medium). Examples of the solvent (or dispersion medium) include water, alcohols (C 100 such as methanol, ethanol, and 2-propanol), and the like. 1-6Examples of suitable solvents include alcohols, ethers (for example, chain ethers such as diethyl ether, and cyclic ethers such as tetrahydrofuran and 1,4-dioxane), ketones (chain ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone), and esters (acetic acid esters such as ethyl acetate and butyl acetate). Among these, aqueous solvents such as water, alcohols, ethers, and acetone are preferred, and water is particularly preferred when preparing a liquid composition such as an emulsion, as will be described later.

[0094] These solvents can be used alone or in combination as a mixed solvent of two or more kinds, for example, a mixed solvent of water and an alcohol such as methanol is preferred. The ratio of the solvent may be appropriately selected depending on the application, and may be, for example, 10 to 10,000 parts by mass (e.g., 50 to 3,000 parts by mass), preferably about 100 to 1,000 parts by mass, per 100 parts by mass of the total amount of the polymerization components.

[0095] The radical polymerization reaction is preferably carried out in an atmosphere of an inert gas, for example, nitrogen gas or a rare gas such as helium gas or argon gas. The reaction temperature (polymerization temperature) may be, for example, 10 to 150°C (e.g., 30 to 120°C), preferably 60 to 100°C, more preferably about 70 to 90°C, for example, 40 to 80°C, and particularly preferably about 50 to 70°C. If the reaction temperature (polymerization temperature) is too high, it may be difficult to improve the molecular weight. The reaction time may be, for example, 0.5 to 24 hours, preferably 1 to 12 hours, and more preferably about 2 to 8 hours.

[0096] After the reaction is complete, the reaction mixture can be separated and purified by a conventional separation method, such as filtration, concentration, drying, extraction, reprecipitation, column chromatography, or a combination thereof. Furthermore, the reaction mixture after the reaction may be used as an adhesive or pressure-sensitive adhesive (or glue), paint, coating agent, or the like in the form of a liquid composition (solution, dispersion, emulsion, or the like) containing a thermoplastic resin without any particular purification.

[0097] 3HB side chain introduction process Furthermore, the thermoplastic resin does not necessarily have to be prepared through the polymerization step, but may be prepared through a 3HB side chain introduction step in which 3HB is reacted with the side chain of the resin through a polymer reaction.

[0098] A representative method may be a method in which a polymer containing the compound represented by formula (3) as a polymerization component (e.g., a polymer containing structural units derived from an alkenyl alkanoate such as vinyl acetate) or a saponified product of this polymer [partially or completely saponified product (e.g., polyvinyl alcohol, which is a saponified product of polyvinyl acetate)] is reacted (transesterification or esterification) with 3-hydroxybutyric acid represented by formula (2). For example, the transesterification reaction may be carried out under reaction conditions (catalyst, temperature, etc.) similar to those described in the above section (Method for producing the compound represented by formula (1)), and the esterification reaction may also be carried out under conventional reaction conditions.

[0099] (Characteristics of thermoplastic resin) Although thermoplastic resins have a skeleton (3HB units) derived from 3HB, their molecular weight can be easily and efficiently increased, resulting in excellent resin properties, moldability (productivity), etc. Although the compound (monomer) represented by the formula (1) is heat-sensitive and easily decomposed, its polymer, the thermoplastic resin, appears to be stable against heat.

[0100] The average molecular weight of the thermoplastic resin can be measured in terms of polystyrene by gel permeation chromatography (GPC) or the like. The weight-average molecular weight Mw may be, for example, about 5,000 to 2,000,000 (e.g., 10,000 to 1,000,000), preferably about 30,000 to 300,000 (e.g., 50,000 to 100,000), and more preferably about 40,000 to 200,000 (e.g., 60,000 to 150,000). The number-average molecular weight Mn may be, for example, about 5,000 to 1,000,000 (e.g., 7,000 to 100,000), preferably about 10,000 to 50,000 (e.g., 10,000 to 40,000), or about 30,000 to 80,000. The molecular weight distribution (polydispersity) Mw / Mn may be, for example, about 1 to 30 (e.g., 1.2 to 10), and preferably about 1.5 to 6 (e.g., 2 to 4). If the average molecular weight, such as the weight average molecular weight Mw or the number average molecular weight Mn, is too low, the resin characteristics (physical properties as a polymer) and moldability (productivity) may be easily reduced.

[0101] In this specification and claims, the weight average molecular weight Mw, number average molecular weight Mn and molecular weight distribution Mw / Mn can be measured by the method described in the examples below.

[0102] The thermoplastic resin may also be a water-insoluble resin that does not dissolve in water or aqueous solvents (e.g., alcohols such as methanol) at, for example, about 20 to 30°C, and preferably does not dissolve even at about 50 to 90°C (e.g., 60 to 80°C), and may be used in applications requiring a certain degree of water resistance (hot water resistance or water insolubility).

[0103] Furthermore, the thermoplastic resin may be a biodegradable resin that is biodegradable under specified conditions such as anaerobic conditions, and the biogasification rate (carbon mole % based on the carbon in the thermoplastic resin (test piece)) after 7 days under anaerobic conditions may be 2% or more (e.g., 5 to 70%), preferably 10% or more (e.g., 20 to 50%), and more preferably about 25% or more (e.g., 30 to 45%, preferably 35 to 40%).

[0104] In this specification and claims, the biogasification rate can be measured by the method described in the examples below.

[0105] Thus, because the thermoplastic resin of the present invention can be biodegraded relatively quickly under certain conditions due to the 3HB skeleton, the present invention encompasses a method for improving (or imparting) the biodegradability of a thermoplastic resin by introducing a structural unit represented by formula (4) into the thermoplastic resin (e.g., by using a compound represented by formula (1) as a polymerization component as in the polymerization step, or by introducing a 3HB skeleton into a side chain as in the 3HB side chain introduction step), as well as a method for decomposing the thermoplastic resin by exposing it to anaerobic conditions. In particular, by introducing a structural unit represented by formula (4) into a thermoplastic resin, it appears that decomposition can be easily and efficiently improved (promoted or induced) even if the thermoplastic resin contains other structural units that are difficult to decompose.

[0106] Although the conditions for biodegrading a thermoplastic resin may be either aerobic or anaerobic, biodegradable resins that are generally anaerobic are valuable. Therefore, the thermoplastic resin of the present invention, which can be effectively decomposed even under anaerobic conditions, is highly useful. Therefore, the thermoplastic resin of the present invention may be, for example, immersed in water (e.g., in a natural environment (the natural world) such as the ocean, rivers, or lakes, or in an artificially controlled environment such as an anaerobic tank), or buried in soil (or soil). It may also be left in a natural environment (in water or soil), particularly in the ocean (seabed). Even when the thermoplastic resin is used for applications requiring water insolubility (even if it is water insolubility during use), the 3HB skeleton of the structural unit represented by formula (4) can be biodegraded relatively quickly after use under anaerobic conditions in a natural environment (e.g., the ocean). When the 3HB skeleton, which is the side chain portion, biodegrades, the main chain portion contains PVA units (R in formula (5)). 4 Although PVA itself is water-soluble and a biodegradable resin as described in Non-Patent Document 2, it can be a resin that does not become microplastics in the ocean, etc., because it leaves behind units of PVA (each unit corresponds to a unit where PVA is a hydrogen atom).

[0107] The present invention also encompasses molded articles containing at least a thermoplastic resin. The molded articles can be used for a variety of purposes, taking advantage of the excellent resin properties and productivity, and can also be effectively used for disposable products, etc., because they are particularly biodegradable.

[0108] The molded article may or may not contain other thermoplastic resins different from the thermoplastic resin, conventional additives, etc. Examples of additives include fillers or reinforcing agents, colorants such as dyes and pigments, conductive agents, flame retardants, plasticizers, lubricants, mold release agents, antistatic agents, dispersants, flow control agents, leveling agents, antifoaming agents, surface modifiers, hydrolysis inhibitors, carbon materials, stabilizers, and stress-reducing agents. Examples of stabilizers include antioxidants, ultraviolet absorbers, and heat stabilizers. Examples of stress-reducing agents include silicone oil, silicone rubber, various plastic powders, and various engineering plastic powders. These additives may be used alone or in combination.

[0109] The total proportion of other thermoplastic resins and conventional additives in the molded article may be, for example, 50% by mass or less (e.g., 0 to 30% by mass), preferably about 10% by mass or less (e.g., 0 to 5% by mass). If the proportion of other thermoplastic resins and conventional additives is too high, biodegradability may decrease.

[0110] The shape of the molded body is not particularly limited, and examples thereof include one-dimensional structures such as linear, fibrous, and thread-like structures, two-dimensional structures such as film-like, sheet-like, and plate-like structures, and three-dimensional structures such as rod-like, hollow (tubular), container-like, and bag-like structures.

[0111] The method for producing the molded body is not particularly limited, and the molded body may be produced by, for example, injection molding, injection compression molding, extrusion molding, transfer molding, blow molding, pressure molding, casting molding, or the like, or may be formed into a film or membrane by coating or applying in the form of a liquid composition (such as a solution, dispersion, or emulsion). [Example]

[0112] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Evaluation methods are described below.

[0113] [Evaluation method] ( 1 H-NMR) In Examples 1 to 3, a nuclear magnetic resonance spectrometer (JASCO Corporation, "JNM-GSX270") was used to dissolve a sample in CDCl3, 1 The H-NMR spectrum (270 MHz) was measured.

[0114] In Examples 4 and 5, a nuclear magnetic resonance apparatus ("AVANCE III HD 300 MHz" manufactured by Bruker Biospin) was used, and the sample was dissolved in CDCl3, 1 The H-NMR spectrum (300 MHz) was measured.

[0115] (GC / MS) Measurements were performed using a gas chromatograph mass spectrometer (GC / MS) (JEOL "JMSQ1050GC Ultra Quad GC / MS") under conditions of an ionization temperature of 250°C, an ionization current of 100 μA, and an ionization energy of 70 eV.

[0116] (GPC (gel permeation chromatography)) Using a GPC measurement device (JASCO Corporation, "GL-7400 Series"), the sample was dissolved in tetrahydrofuran (THF) and measured at a flow rate of 1 mL / min using RI detection, and the number-average molecular weight Mn and weight-average molecular weight Mw were calculated in terms of standard polystyrene.

[0117] (Biodegradation test) The polymer obtained in the Examples or Comparative Examples (125 mg in dry weight equivalent) was mixed with 30 mL of methane fermentation sludge and incubated in an anaerobic atmosphere at 55°C. The amount of methane gas produced by this methane fermentation treatment was measured, and the biogasification rate (or biodegradation rate) was calculated according to the following formula. In this test, sludge collected from a fermentation tank in a methane fermentation facility operated at a fermentation temperature of 55°C was used as the methane fermentation sludge.

[0118] (Biogasification rate or biodegradation rate) [%] = 100 × (COD equivalent of methane generated) / (COD equivalent of polymerized matter)

[0119] [Example 1] Synthesis of (R)-3-hydroxybutyric acid vinyl ester 1

[0120] [ka]

[0121] 30.3 g (291 mmol) of (R)-3-hydroxybutyric acid ((R)-3HB) with a 99% ee or higher, represented by formula (2-1), was dissolved in 279.6 g (3247 mmol) of vinyl acetate (VAc) represented by formula (3-1), and 0.91 g (1.96 mmol) of palladium acetate was added. This mixture was heated and stirred in an oil bath set at 60 °C for 17 hours. The resulting reaction solution was concentrated under reduced pressure using an evaporator set at 60 °C to remove unreacted vinyl acetate, yielding 37.4 g of crude product. This crude product was then distilled under reduced pressure at 0.4 to 0.6 kPa and a top temperature (the temperature at the top of the distillation apparatus (distillation column)) of 63 to 73 °C, yielding a total of 19.33 g of a transparent liquid (51% yield). 1 H-NMR and GC / MS measurements confirmed that this transparent liquid was (R)-3-hydroxybutyric acid vinyl ester (hereinafter also referred to as (R)-VHB) represented by formula (1-1). 1 The results of H-NMR spectrum measurement are shown below.

[0122] 1 H-NMR(270MHz,CDCl3):δ(ppm)=1.27(d,3H,CH3 -), 2.50-2.68(d,2H,-CH-C H2 -C(=O)-O-), 3.10-3.70(br,1H,-O H ), 4.27(m, 1H, CH3-C H -), 4.78(dd,2H,-O-CH=C H2 ), 7.28(t,1H,-OC H =CH2).

[0123] [Example 2] Synthesis of poly(R)-3-vinyl hydroxybutyrate 1

[0124] [ka]

[0125] 5.23 g (40.2 mmol) of (R)-VHB obtained in Example 1 was suspended in 50 mL of water. The (R)-VHB did not completely dissolve in water, resulting in phase separation. 0.01 g (0.04 mmol) of ammonium peroxodisulfate (hereinafter also referred to as APS) was added to this suspension, and the mixture was heated and stirred at an oil bath temperature of 80°C for 5 hours under an argon stream. The reaction solution was not a homogeneous solution, but rather phase-separated (i.e., the polymer was water-insoluble). The reaction solution was concentrated under reduced pressure to obtain the polymer. 1 H-NMR spectroscopy confirmed that the resulting polymer was poly(R)-3-vinyl hydroxybutyrate (hereinafter referred to as Poly((R)-VHB) or P((R)-VHB)) having the repeating unit represented by formula (4-1). GPC analysis also revealed that the number-average molecular weight Mn of this polymer was 18,532 and the weight-average molecular weight Mw was 61,597. 1 The results of H-NMR spectrum measurement are shown below.

[0126] 1 H-NMR(270MHz,CDCl3):δ(ppm)=1.10-1.32(3H,C H3 -), 1.70-1.95(2H,-C H2 -CH(-O-)-), 2.32-2.73(2H,-CH-CH2 -C(=O)-O-), 4.15-4.31(1H,CH3-C H -), 4.70-5.10(1H,-CH2-C H (-O-)-), 6.70-6.88(1H,-O H ).

[0127] [Example 3] Synthesis of poly(R)-3-vinyl hydroxybutyrate 2 10.42 g (80.1 mmol) of (R)-VHB obtained in Example 1 was dissolved in 10 mL of methanol. Next, 0.0268 g (0.12 mmol) of APS was dissolved in 10 mL of water. These two solutions were mixed and heated and stirred under an argon atmosphere at an oil bath temperature of 80°C for 6 hours, resulting in a highly viscous, transparent liquid. The mixture was homogeneous before the reaction, but separated into two layers after the reaction. 8.64 g of this reaction solution was separated and concentrated under reduced pressure using an evaporator set to 60°C, and the concentrate was added dropwise to 50 mL of toluene. The supernatant of this mixture was removed and dried under reduced pressure using an evaporator set to 60°C, yielding 0.31 g of a concentrate. 1 H-NMR confirmed that the polymer was Poly((R)-VHB). GPC analysis revealed that the number-average molecular weight Mn of this polymer was 11,029 and the weight-average molecular weight Mw was 80,054. 1 The results of the H-NMR spectrum measurement were the same as in Example 2.

[0128] [Example 4] Synthesis of (R)-3-hydroxybutyrate vinyl-vinyl acetate copolymer 1

[0129] [ka]

[0130] 0.4 g (3.08 mmol) of the (R)-VHB obtained in Example 1 and 2.39 g (27.72 mmol) of vinyl acetate were dissolved in 0.4 mL of methanol. Next, 0.014 g (0.064 mmol) of APS was dissolved in 3 mL of water. These two solutions were mixed and heated and stirred under a nitrogen stream at an oil bath temperature of 80°C for 7 hours, resulting in a highly viscous, transparent liquid. 30 mL of toluene was added to the reaction solution, and the resulting white precipitate was collected by suction filtration. This was then dried under vacuum at 60°C to obtain 1.8 g of a concentrate (polymer). GPC analysis revealed that the number-average molecular weight Mn of this polymer ((R)-VHB-vinyl acetate copolymer) was 34,962 and the weight-average molecular weight Mw was 946,989, indicating that it was water-insoluble. When 500 mg of the dried copolymer was added to 10 mL of distilled water and heated to 70°C for 1 hour, it did not dissolve in the distilled water and remained solid, demonstrating high water resistance (hot water resistance). 1 The results of H-NMR spectroscopy are shown below. The molar ratio of the (R)-VHB-derived units to the vinyl acetate-derived units in the copolymer was approximately 10 / 90 (the same as the feed ratio).

[0131] 1 H-NMR(300MHz,CDCl3):δ(ppm)=1.15-1.35(3H,C H3 -C(-OH)-CH2-), 1.70-1.98(2H,-C H2 -CH(-O-)-), 1.98-2.15(3H,C H3 -C(=O)-O-), 2.35-2.55(2H,-CH-C H2 -C(=O)-O-), 4.15-4.32(1H,CH3-C H -), 4.75-5.15(1H,-CH2-C H (-O-)-), 3.20-3.70(1H,-O H ).

[0132] [Example 5] Synthesis of (R)-3-hydroxybutyrate vinyl-vinyl acetate copolymer 2 2.00 g (15.38 mmol) of (R)-VHB obtained in Example 1 and 1.32 g (15.33 mmol) of vinyl acetate were dissolved in 0.4 mL of methanol. Next, 0.014 g (0.064 mmol) of APS was dissolved in 3 mL of water. These two solutions were mixed and heated and stirred in a nitrogen stream at an oil bath temperature of 80°C for 7 hours, resulting in a highly viscous, transparent liquid. 30 mL of toluene was added to the reaction solution, and the resulting white precipitate was collected by suction filtration. This was dried in vacuo at 60°C to obtain 2.5 g of a concentrate (polymer). The resulting polymer ((R)-VHB-vinyl acetate copolymer) 1 The results of H-NMR spectroscopy are shown below. The copolymer was water-insoluble, and when 500 mg of the dried copolymer was added to 10 mL of distilled water and heated to 70°C for 1 hour, it did not dissolve in the distilled water and remained solid, demonstrating high water resistance (hot water resistance). The molar ratio of (R)-VHB-derived units to vinyl acetate-derived units in the copolymer was approximately 50 / 50 (the same as the feed ratio).

[0133] 1 H-NMR(300MHz,CDCl3):δ(ppm)=1.12-1.37(3H,C H3 -C(-OH)-CH2-), 1.65-2.00(2H,-C H2 -CH(-O-)-), 2.00-2.15(3H,C H3 -C(=O)-O-), 2.32-2.57(2H,-CH-C H2 -C(=O)-O-), 4.13-4.37(1H,CH3-C H -), 4.71-5.16(1H,-CH2-C H (-O-)-). Note that -O H was broad and difficult to attribute.

[0134] [Example 6] A biodegradation test of the Poly((R)-VHB) obtained in Example 2 revealed that 36.8% had been converted into biogas after 7 days. Furthermore, after 7 days, most of the Poly((R)-VHB) had dissolved, but some remained in solid form.

[0135] [Comparative Example 1] A biodegradation test was conducted on commercially available polyvinyl alcohol (PVA) (Kanto Chemical Co., Ltd. "Polyvinyl Alcohol 500," degree of polymerization 500, degree of saponification = 86.5-89.0%). After 7 days, the biogasification rate was 4.1%, indicating slow decomposition. After 7 days, all of the polyvinyl alcohol had dissolved, and no solid matter was observed.

[0136] Based on the biodegradability evaluation results of Example 6 and Comparative Example 1, it is believed that under anaerobic conditions, Poly((R)-VHB) is preferentially biodegraded, starting with the 3HB skeleton of the highly biodegradable side chain, as shown in the following formula, with PVA corresponding to the main chain being produced as the remainder. It is believed that this PVA gradually biodegrades as it dissolves in water, and therefore would not become microplastics even if released into the ocean.

[0137] [ka]

[0138] [Example 7] A biodegradation test was conducted on the (R)-VHB-vinyl acetate copolymer (copolymerization ratio (molar ratio) = 50 / 50) obtained in Example 5, and the biogasification rate after 210 days was 67%.

[0139] Comparative Example 2 In a biodegradation test of polyvinyl acetate (PVAc), no decomposition was observed even after 210 days. The PVAc used was prepared as follows.

[0140] Specifically, 2.8 g of vinyl acetate monomer was dissolved in 4 mL of methanol, and then a mixed solution of 0.01 g of ammonium peroxodisulfate and 4 mL of distilled water was added and reacted for 8 hours at 80 °C. The resulting reaction product was filtered, washed with 20 mL of toluene, and vacuum dried at 60 °C to obtain PVAc.

[0141] In Comparative Example 2, PVAc did not decompose, whereas in Example 7, more than half of the copolymer was decomposed. This suggests that the (R)-VHB units in the copolymer promote (or induce) the decomposition of the vinyl acetate units.

[0142] Comparative Example 3 A biodegradation test was conducted on commercially available polyvinyl alcohol (PVA) (Kanto Chemical Co., Ltd.'s "Polyvinyl Alcohol 500," polymerization degree 500, saponification degree = 86.5-89.0%), and the biogasification rate after 210 days was 24%.

[0143] [Example 8] Synthesis of (R)-3-hydroxybutyric acid vinyl ester 2 61.11 g (587 mmol) of (R)-3HB (>99% ee) was dissolved in 536 g (6226 mmol) of vinyl acetate. 0.51 g (2.27 mmol, 0.0039 eq.) of palladium acetate and 0.43 g (7.66 mmol, 0.013 eq.) of potassium hydroxide were added. The reaction mixture was stirred at room temperature under an argon atmosphere. After 17 hours, the reaction mixture was sampled and analyzed by GC-MS. (R)-3HB was almost completely consumed. Saturated aqueous NaHCO3 was added to the reaction mixture and stirred. Further NaHCO3 was added until the effervescence subsided. The organic phase was separated, dried over anhydrous MgSO4, and concentrated under reduced pressure at room temperature. The concentrated residue was distilled under reduced pressure. (R)-VHB was obtained with a GC purity of >99% and a total yield of 48%.

[0144] [Example 9] Synthesis of poly(R)-3-hydroxyvinyl butyrate 3 An APS solution was prepared by dissolving 50.0 mg of APS (10-hour half-life temperature: 62°C) in 10.0 mL of water. Separately, an (R)-VHB solution was prepared by dissolving 7.0005 g of the (R)-VHB obtained in Example 8 in 7.00 mL of 50% MeOHaq. The entire (R)-VHB solution was degassed with argon for 5 minutes, and 1.75 mL of APS solution was added to prepare a reaction solution (APS / (R)-VHB ≈ 0.0007 mol / mol). The reaction solution was heated to 60°C under an argon atmosphere. After 6 hours, it became a viscous liquid. GPC analysis of the resulting reaction solution revealed a number-average molecular weight (Mn) of 55,006 and a weight-average molecular weight (Mw) of 139,860. The reaction mixture was dried under reduced pressure at 60°C, and 500 mg of the dried product [Poly((R)-VHB)] was added to 10 mL of distilled water, heated to 70°C, and maintained for 1 hour. The product did not dissolve in the distilled water and remained solid, demonstrating high water resistance (hot water resistance). [Industrial Applicability]

[0145] The ethylenically unsaturated compound of the present invention can be suitably used as a resin raw material (or polymerization component) [particularly as a resin raw material for biodegradable resins], and even when 3HB units are introduced into a resin by chemical synthesis, the molecular weight of the resulting thermoplastic resin can be effectively or easily (or efficiently) increased, thereby improving the resin properties and moldability (or productivity).

[0146] Therefore, they can be used in a variety of fields, such as adhesives or pressure-sensitive adhesives (or glue), paints, inks, paper processing agents (sizing agents, coating agents, etc.), chewing gum bases, abrasives (scrubbing agents such as toothpaste, facial cleansers, and body washes), antistatic agents, electric and electronic materials (e.g., carrier transport agents, light-emitting bodies, organic photoconductors, etc.), electric and electronic parts or devices (e.g., optical lenses, optical films, optical disks, inkjet printers, digital paper, organic semiconductor lasers, dye-sensitized solar cells, etc.), and machine parts or devices (e.g., automobiles, aerospace materials, sensors, etc.).

[0147] Furthermore, because the 3HB-derived skeleton is biodegradable under aerobic and anaerobic conditions (particularly preferably under anaerobic conditions), it can be suitably used in disposable products (disposable products) such as tableware (straws, cups, plates, chopsticks, spoons, forks, etc.) and packaging materials (e.g., containers for food, daily necessities, electrical and electronic devices, and their components; bags such as shopping bags, Eco Bags (registered trademark), garbage bags, and paper bags), particularly as adhesives or pressure-sensitive adhesives (or glues) used in these disposable products (e.g., glues used in paper containers (e.g., tableware such as paper cups)). Therefore, it is useful for solving environmental issues such as microplastics, which have become increasingly important in recent years. It can also be used in applications requiring biocompatibility, such as the medical field (e.g., medical devices, medical disposable products, etc.) and the cosmetics field.

Claims

1. The following formula (1) 【Chemistry 1】 (In the formula, R １ represents a hydrogen atom or an alkyl group.) A method for producing a compound represented by the formula: The following formula (2) 【Chemistry 2】 and 3-hydroxybutyric acid represented by the following formula (3): 【Transformation 3】 (wherein R 2 represents a hydrogen atom or an alkyl group, and R 1 is the same as in formula (1) above.) and a compound represented by the formula:

2. The formula (1) is represented by the following formula (1R): 【Chemistry 4】 (In the formula, R １ is the same as the above formula (1). The method according to claim 1, wherein

3. In the formula (1), R １ is a hydrogen atom or C １－４ 3. The method according to claim 1, wherein the alkyl group is an alkyl group.

4. The method of any one of claims 1 to 3, wherein the reaction is carried out at 20 to 100°C in the presence of at least one compound selected from a mercury compound, a ruthenium compound and a palladium compound.

5. The following formula (4) 【Transformation 5】 (In the formula, R １ is the same as formula (1) in claim 1. A thermoplastic resin containing a structural unit represented by the formula:

6. The constitutional unit represented by the formula (4) is represented by the following formula (4R): 【Transformation 6】 (In the formula, R １ is the same as formula (1) in claim 1. The thermoplastic resin according to claim 5, which contains a structural unit represented by the formula:

7. 7. The thermoplastic resin according to claim 5, wherein the proportion of the structural unit represented by formula (4) is 5 to 100 mol % based on all structural units.

8. The thermoplastic resin according to any one of claims 5 to 7, having a weight average molecular weight Mw of 5,000 to 2,000,000.

9. The thermoplastic resin according to any one of claims 5 to 8, which is a water-insoluble resin.

10. The thermoplastic resin according to any one of claims 5 to 9, which is a biodegradable resin.

11. The thermoplastic resin according to any one of claims 5 to 10, wherein the biogasification rate after 7 days under anaerobic conditions is 2% or more.

12. A step of polymerizing a polymerization component containing the compound represented by formula (1) according to any one of claims 1 to 3; and A method for producing the thermoplastic resin according to any one of claims 5 to 11, comprising at least one step selected from the group consisting of a step of reacting a polymer of a polymerization component containing a compound represented by formula (3) according to claim 1 or a saponified product thereof with 3-hydroxybutyric acid represented by formula (2) according to claim 1.

13. A method for improving the biodegradability of a thermoplastic resin by introducing a constitutional unit represented by formula (4) according to any one of claims 5 to 7 into the thermoplastic resin.

14. A method for decomposing a thermoplastic resin, comprising exposing the thermoplastic resin according to any one of claims 5 to 11 to aerobic or anaerobic conditions.

15. 15. The method of claim 14, wherein the plant is immersed in water or buried in soil.

16. A molded article comprising the thermoplastic resin according to any one of claims 5 to 11.

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