JP2019119840A - Aliphatic polyester resin composition - Google Patents

Abstract

To provide a resin composition containing polyhydroxyalkanoate, and having improved solidification rate, and a molded body by molding the same.SOLUTION: There is provided a polyester resin composition containing polyhydroxyalkanoate and nucleic acid bases. Content of the nucleic acid bases may be 0.01 to 10 pts.wt. based on 100 pts.wt. of the polyhydroxyalkanoate, and the nucleic acid bases may be orotic acid. The polyhydroxyalkanoate may be poly(3-hydroxyalkanoate).SELECTED DRAWING: None

Description

  The present invention relates to an aliphatic polyester resin composition containing polyhydroxyalkanoate (eg, poly (3-hydroxyalkanoate)), and a molded article obtained by molding the same.

  In the past, plastics have been disposable in view of ease of processing and use, difficulty of reuse, and hygiene problems. However, as plastics are used and disposed in large quantities, the problems associated with their landfill and incineration are being highlighted. Such problems include, for example, the shortage of landfills, the impact on ecosystems due to non-degradable plastics remaining in the environment, the generation of harmful gases during combustion, global warming due to large amounts of combustion heat, etc. There is a large burden on the environment.

  In recent years, development of biodegradable plastics has been promoted as a solution to the above-mentioned problems of plastic waste. Generally, biodegradable plastics are 1) microbial polyesters such as polyhydroxyalkanoates, 2) chemically synthesized aliphatic polyesters such as polylactic acid and polycaprolactone, and 3) natural highs such as starch and cellulose acetate It is roughly divided into three types such as molecules. Many of the chemically synthesized aliphatic polyesters do not undergo anaerobic decomposition, and therefore there are restrictions on decomposition conditions at the time of disposal. In addition, starch is non-thermoplastic and brittle, and has problems such as poor water resistance.

  On the other hand, among polyhydroxyalkanoates, poly (3-hydroxyalkanoate) (hereinafter sometimes abbreviated as P3HA) is excellent in both aerobic and anaerobic decomposability and generates toxic gas at the time of combustion. It is a plastic that can be produced by microorganisms using plant materials, has high characteristics of high molecular weight, and is carbon neutral without increasing carbon dioxide on the earth. The P3HA is classified into aliphatic polyesters, but the properties of the polymer are significantly different from those of the chemically synthesized aliphatic polyesters and natural polymers described above, and they have the property of being degraded under anaerobic and excellent moisture resistance, The point that high molecular weight can be achieved is a remarkable performance.

  On the other hand, P3HA still has room for improvement in terms of processability. The main need for improvement is the poor processability stemming from the slow crystallization rate. Various studies have been conducted as a method of increasing such crystallization rate (see, for example, Patent Document 1).

JP, 2010-47732, A

  However, the prior art concerning the nucleating agent of polyhydroxyalkanoate (for example, poly (3-hydroxyalkanoate)) is currently at present still a room for improvement in terms of improvement of crystallization rate and hence improvement of formability. is there. Further, from the viewpoint of preventing contamination of the molding machine at the time of molding processing, development of a crystal nucleating agent which is as difficult as possible to sublimation or bleed out is desired.

  Accordingly, the present invention provides a composition comprising a polyhydroxyalkanoate (for example, poly (3-hydroxyalkanoate)), wherein the resin composition has an improved solidification rate, and a molded article obtained by molding the same. Intended to be provided.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that, by blending a specific compound with polyhydroxyalkanoate (for example, poly (3-hydroxyalkanoate)), It has been found that polyhydroxyalkanoate can be solidified at a high solidification rate, and nucleic acid bases are difficult to sublimate and bleed out, and the present invention has been completed.

  That is, the present invention provides, for example, the following inventions.

[1] A polyester resin composition containing polyhydroxyalkanoate and nucleic acid bases.

[2] The polyester resin composition according to [1], wherein the nucleobases are at least one selected from the group consisting of uracil, thymine and derivatives thereof.

[3] The polyester resin composition according to [2], wherein the nucleic acid base is orotic acid.

[4] The polyester resin composition according to any one of [1] to [3], wherein the content of nucleic acid bases is 0.01 to 10 parts by weight with respect to 100 parts by weight of polyhydroxyalkanoate. .

[5] The polyester resin according to any one of [1] to [4], wherein polyhydroxyalkanoate is at least one selected from the group consisting of poly (3-hydroxyalkanoate) and polylactic acid Composition.

[6] The polyester resin composition according to any one of [1] to [4], wherein the polyhydroxyalkanoate is poly (3-hydroxyalkanoate).

[7] Poly (3-hydroxyalkanoate) is poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3) The polyester resin composition according to [6], which is at least one selected from the group consisting of -hydroxyhexanoate) and poly (3-hydroxybutyrate-co-4-hydroxybutyrate).

  Since the polyester resin composition of the present invention has the above constitution, the solidification speed is high, and the processability and processing speed in various processes such as injection molding, film forming, blow molding, fiber spinning, extrusion foaming, bead foaming are improved. The molded product can be produced with excellent productivity. Moreover, by using nucleic acid bases as a crystal nucleating agent, there is also an effect that sublimation and bleed out in the composition are suppressed.

  The polyester resin composition of the present invention contains polyhydroxyalkanoate and nucleic acid bases as essential components.

(Polyhydroxyalkanoate)
The polyhydroxyalkanoates used in the present invention are polyesters containing hydroxyalkanoic acid units as monomer units. Examples of the hydroxyalkanoic acid include glycolic acid, lactic acid, 6-hydroxycaproic acid, 3-hydroxyalkanoic acid described later, 4-hydroxyalkanoic acid and the like. Specific examples of polyhydroxyalkanoate include polyglycolic acid, polylactic acid, polycaprolactone, poly (3-hydroxyalkanoate) (hereinafter sometimes referred to as "P3HA"), and the like. Among them, P3HA and polylactic acid are preferable, and P3HA is more preferable, in that the effect of the present invention is more remarkably exhibited.

(P3HA)
The P3HA used in the present invention is a polyester containing a 3-hydroxyalkanoic acid unit as a monomer unit, and in particular, the formula: [-CHR-CH ₂ -CO-O-] (wherein R is C _n H A linear or branched alkyl group represented by _{2n + 1} is shown, and n is an integer of 1 or more and 15 or less. The polyester may be a homopolymer, or may be a copolymer containing two or more of the repeating units. Such a copolymer is preferable because the melting point can be lowered as compared with a homopolymer, so that the temperature at the time of melting can be lowered, and deterioration of the composition can be suppressed.

  P3HA may be a polyester containing only 3-hydroxyalkanoic acid units as monomer units, but other hydroxyalkanoic acid units (for example, 4-hydroxyalkanes) may be used together with 3-hydroxyalkanoic acid units as monomer units. It may be a copolyester containing an acid unit). The content ratio of 3-hydroxyalkanoic acid units among all hydroxyalkanoic acid units in the above copolymerized polyester is not particularly limited, but for example, 50 mol% or more is preferable, 60 mol% or more is more preferable, and 70 mol% or more 80 mol% or more is especially preferable, 90 mol% or more is the most preferable.

  Specific examples of P3HA in the present invention include, for example, PHB [poly (3-hydroxybutyrate) or poly 3-hydroxybutyric acid], PHBH [poly (3-hydroxybutyrate-co-3-hydroxyhexanoate)] Or poly (3-hydroxybutyrate-co-3-hydroxyhexanoic acid) !, PHBV [poly (3-hydroxybutyrate-co-3-hydroxyvalerate), or poly (3-hydroxybutyrate-co-3-) Hydroxyvaleric acid]], P3HB4HB [poly (3-hydroxybutyrate-co-4-hydroxybutyrate), or poly (3-hydroxybutyric acid-co-4-hydroxybutyric acid)], poly (3-hydroxybutyrate-) Co-3-hydroxyoctanoate) or poly (3-hydroxybutyrate-co-3-hydroxyoc) Decanoate), and the like. Among these, PHB, PHBH, PHBV, and P3HB4HB are preferable as being industrially easy to produce, and PHBH is more preferable.

  P3 HA is preferably a homopolymer or copolymer containing 3-hydroxybutyrate units from the viewpoint of flexibility and strength. Among them, from the viewpoint of balance between flexibility and strength, it is more preferable that the average composition ratio of 3-hydroxybutyrate units contained in P3HA is 80 mol% to 99 mol%, and 85 mol% to 97 mol%. Those shown are more preferred. If the average composition ratio of 3-hydroxybutyrate units is less than 80 mol%, the rigidity tends to be insufficient, and if it is more than 99 mol%, the flexibility tends to be insufficient.

  In the present invention, P3HA may be used alone or in combination of two or more. Moreover, when using copolymers, such as PHBH, as P3HA, 2 or more types of copolymers from which the average composition ratios of monomer units, such as a 3-hydroxy butyrate unit, differ can also be mixed and used.

  The molecular weight of P3HA used in the present invention is not particularly limited as long as it exhibits substantially sufficient physical properties in the intended use of the final molded product. However, if the molecular weight is low, the strength of the molded article tends to decrease, and if it is high, the processability may decrease and processing may become difficult. Therefore, the molecular weight may be determined in consideration of them. From this viewpoint, the range of the weight average molecular weight of P3HA used in the present invention is preferably 50,000 to 3,000,000, and more preferably 100,000 to 1,500,000. In addition, the weight average molecular weight here refers to what was measured as a molecular weight of polystyrene conversion using the gel permeation chromatography (GPC) using a chloroform eluent. As a column in the said GPC, a column suitable for measuring the said molecular weight may be used.

  Although the glass transition temperature of P3HA used by this invention is not specifically limited, -30-10 degreeC is preferable. In the present invention, the glass transition temperature is measured by differential scanning calorimetry at a heating rate of 10 ° C./min.

  Although it does not specifically limit as a method to manufacture P3HA, For example, the method to which P3HA is produced by the microorganism which has P3HA production ability is mentioned. Such microorganisms are not particularly limited. For example, as PHB-producing bacteria, in addition to Bacillus megaterium discovered in 1925, Capriavidus necator (old classification: Alka And U.S. eutropha (Ralstonia eutropha), Alkaligenes latus (Alcaligenes latus), etc. Moreover, as a copolymer producing bacteria of 3-hydroxybutyrate and other hydroxyalkanoates, Aeromonas which is PHBV and PHBH producing bacteria.・ Cerpent (Aeromonas caviae), P3HB4HB producing bacteria Alkaline Genes Yu Alphagenes eutrophus AC32 strain (Alcaligenes eutrophus AC32, FERM BP-6038), in which a gene of PHA synthetic enzyme group was introduced to increase PHBH productivity, is particularly mentioned as PHHB producing bacteria. (T. Fukui, Y. Doi, J. Bacteriol., 179, p4821-4830 (1997)).

  P3HA can be produced by culturing these microorganisms under appropriate conditions to accumulate P3HA in the cells and recovering the P3HA. Culture conditions including the type of substrate can be optimized according to the microorganism used. In addition to the above-mentioned microorganisms, P3HA can also be produced by culturing genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced, in accordance with the P3HA to be produced.

  The content of polyhydroxyalkanoate (for example, P3HA) in the polyester resin composition of the present invention is not particularly limited, but 10 to 99% by weight is preferable, more preferably 30 to 96% by weight, still more preferably 50 to 96% %. By setting the content of polyhydroxyalkanoate (for example, P3HA) to 10% by weight or more, the degree of biobase and biodegradability as the whole composition tends to be further improved. On the other hand, by setting the content of polyhydroxyalkanoate (for example, P3HA) to 99% by weight or less, the amount of nucleic acid bases is relatively secured, the solidification rate is improved, and the composition is increased by increasing other resins. There is a tendency to further improve the mechanical properties as a whole of the object.

  The polyester resin composition of the present invention may contain a resin (polymer) other than polyhydroxyalkanoate. As resins other than polyhydroxyalkanoate, for example, those having biodegradability such as polybutylene adipate terephthalate copolymer (PBAT), polyprebutylene succinate (PBS), polybutylene succinate adipate copolymer (PBSA), etc. Polyester resin; natural polymers such as starch and cellulose can also be blended. Moreover, thermoplastic resins other than the above can also be blended as needed.

(Nucleic acid bases)
The polyester resin composition of the present invention contains nucleic acid bases as an essential component. The nucleic acid bases are presumed to act as an effective nucleating agent in the polyester resin composition of the present invention. Nucleobases refer to adenine, guanine, thymine, cytosine, uracil and derivatives thereof. Among them, uracil, thymine and derivatives thereof are preferable in view of the crystallization promoting effect and the solidification rate, and orotic acid (alias: olotic acid, uracil-6) which is a derivative in which C-6 position of uracil is substituted by a carboxyl group. -Carboxylic acid, vitamin B ₁₃ ) is more preferred.

  The effect as a nucleating agent can be further enhanced by adding nucleic acid bases after reducing the average particle size (d50) in advance by grinding or the like. The average particle size is preferably 0.1 to 500 μm, more preferably 0.5 to 50 μm. The average particle size can be measured by a laser diffraction / scattering type particle size distribution measuring apparatus.

  As a method of reducing the particle size of nucleic acid bases, conventionally known methods such as collision plate type or powder collision type jet mill, bead mill, hammer mill, etc. can be used besides grinding with a mortar.

  The content of the nucleic acid bases in the polyester resin composition of the present invention is not particularly limited, but from the viewpoint of improving the crystallization rate and the balance of physical properties of the obtained resin composition, polyhydroxyalkanoate (for example, P3HA) 100 0.01 to 10 parts by weight is preferable, more preferably 0.3 to 5 parts by weight, and still more preferably 0.5 to 3 parts by weight with respect to the parts by weight.

  The polyester resin composition of the present invention may further contain other components in addition to the components described above. Other components include various additives such as antioxidants, UV absorbers, colorants such as dyes and pigments, plasticizers, lubricants, mold release agents, inorganic fillers (for example, carbon black, calcium carbonate, silicon oxide , Silicate, zinc flower, high site clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, kieselguhr, dolomite powder, titanium oxide, zinc oxide, antimony oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, Calcium silicate, boron nitride, ammonium chloride, glass fiber, whisker, carbon fiber etc., organic filler (crosslinked polymer polystyrene, rosin metal salt etc .; human hair, wool, bamboo fiber, pulp fiber organic fiber etc) And antistatic agents, fungicides, water repellents, antibacterial agents, foaming agents, flame retardants, crystal nucleating agents and the like. The content of the other components is not particularly limited, and can be appropriately adjusted. The other components may be used alone or in combination of two or more.

  The polyester resin composition of the present invention may contain a plasticizer. The plasticizer is not particularly limited, but, for example, ether plasticizers, ester plasticizers, phthalic acid plasticizers and phosphorus plasticizers are preferable, and from the viewpoint of excellent compatibility with polyhydroxyalkanoate, particularly P3HA, Ether plasticizers and ester plasticizers are more preferable. Examples of ether plasticizers include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol. Examples of ester plasticizers include esters of aliphatic dicarboxylic acids and aliphatic alcohols, and examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, sebacic acid, adipic acid, etc. As aliphatic alcohols, for example, monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-hexanol, n-octanol, 2-ethylhexanol, n-dodecanol, stearyl alcohol, etc .; ethylene glycol, 1, 2 -Propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, dihydric alcohols such as polyethylene glycol, etc. glycerin, Trimethylolpropane, it may be mentioned polyhydric alcohols pentaerythritol and the like. In addition, copolymers (di-copolymers, tri-copolymers, tetra-copolymers, etc.) containing combinations of two or more of the above aliphatic dicarboxylic acids and / or aliphatic alcohols, or homopolymers and copolymers thereof are selected. Two or more blends are mentioned. Furthermore, esters of hydroxycarboxylic acids are also mentioned. The above plasticizers may be used alone or in combination of two or more. The content of the plasticizer can be selected appropriately.

  A fatty acid amide may be added to the resin composition of the present invention as long as the effects of the present invention are not inhibited. In the resin composition of the present invention, it is considered that the fatty acid amide can act as a nucleating agent or as an internal lubricant and an external lubricant.

Examples of fatty acid amides include compounds represented by the formula: R ¹ -C (= O) -NR ² R ³ . Here, R ¹ , R ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. The hydrocarbon group may be saturated or unsaturated. The hydrocarbon group may have no substituent, or may have a substituent such as a hydroxyl group, an alkoxy group, a halogen group, a carboxyl group, an amino group, an amido group and the like. Furthermore, R ¹ and R ² or R ³ may combine to form a cyclic structure.

  Specific examples of fatty acid amides include palmitic acid amide, stearic acid amide, erucic acid amide (EA), behenic acid amide (BA), ricinoleic acid amide, hydroxystearic acid amide, N-oleylpalmitic acid amide, N-stearyl eruka Acid amide, methylene bis lauric acid amide, methylene bis stearic acid amide, methylene bis hydroxy stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid An amide, ethylenebiscaprylic acid amide, ethylenebishydroxystearic acid amide, N, N'-distearyl sebacic acid amide, hexane methylene bis stearic acid amide, etc. are mentioned. One type of fatty acid amide may be used alone, or two or more types may be used in combination.

  As the fatty acid amide, a compound having a melting point of about 100 to 150 ° C. (particularly 100 to 120 ° C.) is preferable. When a fatty acid amide exhibiting such a melting point is blended to P3 HA having a melting point of 90 ° C. or higher, the crystallization speed is improved in molding processing at a temperature 10 to 30 ° C. higher than the melting point of the P3 HA, and molding processability Can be improved.

Among fatty acid amides, preferred are primary amides in which R ¹ represents an aliphatic hydrocarbon group having 1 to 30 carbon atoms (particularly 10 to 20 carbon atoms), and R ² and R ³ each represent a hydrogen atom. Among them, behenic acid amide (melting point 114 ° C.), stearic acid amide (melting point 102 ° C.), ethylenebisstearic acid amide (melting point 147 ° C.), hydroxystearic acid amide (107 ° C.), methylol behenic acid amide (melting point 110 ° C.) Is preferred.

  The content of fatty acid amide in the resin composition of the present invention is not particularly limited, but it is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of polyhydroxyalkanoate (eg P3HA) It is 5 parts by weight, more preferably 0.5 to 1 part by weight. By controlling the content of the fatty acid amide in the above range, the moldability of the resin composition tends to be further improved.

  After melt-kneading as described above, the resin composition of the present invention is extruded into strands and then cut into pellets of particle shape such as columnar, elliptical columnar, spherical, cubic or rectangular solid. be able to. The obtained pellet can be sufficiently dried at 40 to 80 ° C. to remove moisture, and then molded and processed by a known molding method to obtain an arbitrary molded body. Examples of the molding method include film molding, sheet molding, injection molding, blow molding, blow molding, fiber spinning, extrusion foaming, bead foaming and the like.

  Examples of the method for producing a film molded body include T-die extrusion molding, calendar molding, roll molding, and inflation molding. However, the film forming method is not limited to these. The film obtained from the resin composition of the present invention can be thermoformed by heating, vacuum formed, or press formed.

  As a method for producing an injection-molded article, for example, injection molding such as injection molding, gas assist molding, injection compression molding and the like generally employed when molding thermoplastic resin can be adopted. In addition to the above methods, in-mold molding method, gas press molding method, two-color molding method, sandwich molding method, PUSH-PULL, SCORIM, etc. may be adopted according to other purposes. However, the injection molding method is not limited to these.

  The resin composition of the present invention may be processed into a pellet, or a film-like, sheet-like or fiber-like molded article using an extrusion molding machine, or may be processed into a molded article of a predetermined shape by injection molding. It is also possible.

  When the resin composition of the present invention contains a foaming agent, the molded article of the present invention may be a foamable molded article or may be formed into a molded foam by foaming after processing.

  The resin composition of the present invention can be processed into molded articles of various shapes. Examples of the molded body include paper, film, sheet, tube, plate, rod, container, bag, and part. Moreover, in order to improve the physical properties of the molded article of the present invention, a molded article composed of a material different from the resin composition of the present invention (for example, fiber, yarn, rope, woven fabric, knitted fabric, non-woven fabric, paper, Films, sheets, tubes, plates, rods, containers, bags, parts, foams, etc.) can also be combined. The application of the molded article of the present invention is not particularly limited, and can be suitably used in the fields of agriculture, fishery, forestry, horticulture, medicine, hygiene products, clothing, non-clothing, packaging, automobiles, building materials and the like.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<P3HA>
In each example or comparative example, PHBH: poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) was used as P3HA. This PHBH is obtained by recovering PHBH-producing bacteria and then recovering the resin component from the cells, and the HH ratio: the molar fraction (mol%) of 3-hydroxyhexanoate in PHBH is 11 mol%, Mw is 67.2 thousand. In addition, Alcaligenes eutrophus AC32 (J. Bacteriol., 179, 4821 (1997)) which introduce | transduced the PHA synthetic enzyme gene derived from Aeromonas caviae into Alcaligenes eutrophus was used as PHBH production microbe.

<Molecular weight measurement>
The weight average molecular weight Mw of PHBH was determined by GPC measurement. The GPC apparatus used LC-10A system (made by Shimadzu Corp.), the column used GPCK-806M (made by Showa Denko), and column temperature was 40 degreeC. 10 μl of a solution of 3 mg of the target substance in 2 ml of chloroform was injected to determine Mw by polystyrene conversion.

<Additives>
A product from Wako Pure Chemical Industries, Ltd. (special grade reagent) was used as orotic acid monohydrate (hereinafter referred to as orotic acid). The other reagents used were products manufactured by Wako Pure Chemical Industries, Ltd. (special grade reagents).

<Poly lactic acid>
As polylactic acid, crystalline polylactic acid (Ingeo 3251D, manufactured by Nature Works Inc.) was used.

Example 1
The polyester resin composition was manufactured using a small-sized kneader XPlore series MC5 manufactured by DSM. First, as shown in Table 1, 1.5 parts by weight of orotic acid was dry-blended with 100 parts by weight of P3HA (PHBH) to obtain a powder mixture. The powder mixture is melt-kneaded under conditions of a set temperature of 180 ° C., screw rotation speed of 100 rpm, and a kneading time of 3 minutes, and then the melt immediately after being discharged from the kneader is charged into a warm bath of about 55 ° C. It solidified and manufactured the polyester resin composition.

  When manufacturing a polyester resin composition, the time which it took for a molten material to solidify after being injected | thrown-in to a warm water bath was measured as "solidification time." The faster the crystallization, the shorter the solidification time, and the shorter the solidification time, the better the solidification characteristics. Being excellent in solidification characteristics means that it can be solidified quickly during molding processing, and molded articles can be produced with excellent productivity (that is, excellent in moldability). The measurement of solidification time was performed three times in the same procedure and the average value is shown in the table.

<Evaluation of presence or absence of bleed-out>
1 kg of the powder mixture obtained above (obtained by dry blending 1.5 parts by weight of orotic acid with 100 parts by weight of PHBH) with a twin-screw kneading extruder TEM-26SS manufactured by Toshiba Machine Co., Ltd. Melt processing was performed at 150 ° C. to obtain resin pellets. The pellets were melt-processed again at 140 ° C. using a Labo Plastomill Model 30C150 manufactured by Toyo Seiki Co., Ltd. to obtain a T-die sheet having a thickness of about 100 μm. The T-die sheet was left in an oven at 60 ° C. (dry oven DSV602 manufactured by Yamato Scientific Co., Ltd.) for 1 day, and the surface of the sheet was visually observed to determine the presence or absence of bleed-out. The polyester resin composition obtained in Example 1 resulted in no bleed out.

(Examples 2-4, comparative examples 1-5)
The production of the polyester resin composition and the measurement of the setting time were carried out in the same manner as in Example 1 except that the types and amounts of additives were changed as shown in Table 1.

(Comparative example 6)
Solidification test and resin composition in the same manner as in Example 1 except that 1.5 parts by weight of orotic acid is used as an additive with respect to 100 parts by weight of crystalline polylactic acid, and the temperature of the bath for solidification is 80.degree. Production of

(Comparative example 7)
A solidification test and production of a resin composition were carried out in the same manner as in Comparative Example 6 except that the types of additives were changed to those shown in Table 2.

Claims (7)

  A polyester resin composition comprising polyhydroxyalkanoate and nucleic acid bases.   The polyester resin composition according to claim 1, wherein the nucleobases are at least one selected from the group consisting of uracil, thymine and derivatives thereof.   The polyester resin composition according to claim 2, wherein the nucleic acid bases are orotic acid.   The polyester resin composition according to any one of claims 1 to 3, wherein the content of the nucleic acid bases is 0.01 to 10 parts by weight with respect to 100 parts by weight of polyhydroxyalkanoate.   The polyester resin composition according to any one of claims 1 to 4, wherein the polyhydroxyalkanoate is at least one selected from the group consisting of poly (3-hydroxyalkanoate) and polylactic acid.   The polyester resin composition according to any one of claims 1 to 4, wherein the polyhydroxyalkanoate is poly (3-hydroxyalkanoate). Poly (3-hydroxyalkanoate) is poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), poly (3-hydroxybutyrate-co-3-hydroxyhexa) The polyester resin composition according to claim 6, which is at least one selected from the group consisting of (noate) and poly (3-hydroxybutyrate-co-4-hydroxybutyrate).