Method for controlling marine biodegradation rate of biodegradable resin

Abstract

To develop a technique for accelerating the marine biodegradation rate of a biodegradable resin.SOLUTION: The present invention provides a marine biodegradation rate accelerator for a biodegradable resin, the accelerator comprising 16-hydroxyhexadecanoic acid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for controlling the marine biodegradation rate of biodegradable resins using 16-hydroxyhexadecanoic acid (16HHD), etc.

Background Art

[0002] Many chemically synthesized aliphatic polyesters such as polybutylene succinate-co-adipate (PBSA) and polybutylene succinate (PBSu) are biodegradable materials having excellent physical properties and processability. On the other hand, their biodegradability varies greatly depending on the environment, and particularly the biodegradation rate in the marine environment is low.

[0003] Against such a background, methods for accelerating the decomposition of biodegradable resins in the marine environment have been proposed. For example, Patent Documents 1 and 2 disclose methods of adding polyhydroxyalkanoic acid (PHA) or polycaprolactone (PCL) having high marine biodegradability to materials such as PBSA and PBSu having low marine biodegradability. Patent Documents 3 and 4 disclose methods of increasing the decomposition rate by adding the resin hydrolytic enzyme to resin articles. Patent Document 5 discloses a method of adding nitrogen compounds and phosphorus compounds to increase the decomposition rate in the marine environment. However, further development of methods for accelerating the decomposition of biodegradable resins in the marine environment has been demanded.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above situation, an object of the present invention is to develop a technology for accelerating the marine biodegradation rate of biodegradable resins.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the marine biodegradation rate of biodegradable resins can be accelerated by contacting 16-hydroxyhexadecanoic acid with biodegradable resins. Based on such findings, the present invention has been completed. That is, the gist of the present invention relates to the following.

[0007] [1] An accelerator for promoting the marine biodegradation rate of biodegradable resins, containing 16-hydroxyhexadecanoic acid. [2] The accelerator for promoting the marine biodegradation rate, wherein the biodegradable resin is a polyester resin. [3] The accelerator for promoting the marine biodegradation rate, wherein the biodegradable resin is one or more selected from polybutylene succinate and polybutylene succinate / adipate. [4] A marine biodegradable resin composition having an accelerated marine biodegradation rate, containing the biodegradable resin, and the accelerator for promoting the marine biodegradation rate. [5] A molded article formed from the marine biodegradable resin composition. [6] A method for accelerating the biodegradation rate of a biodegradable resin in a marine environment, by contacting the biodegradable resin with the accelerator for promoting the marine biodegradation rate. [7] A method for biodegrading a biodegradable resin in a marine environment, by contacting the biodegradable resin with the accelerator for promoting the marine biodegradation rate.

[0008] In addition, the present invention can also adopt the following configurations. [8] Use of 16-hydroxyhexadecanoic acid for accelerating the marine biodegradation rate of biodegradable resins. [9] 16-Hydroxyhexadecanoic acid for use in accelerating the marine biodegradation rate of biodegradable resins.

[10] Use of 16-hydroxyhexadecanoic acid in the production of an accelerator for accelerating the marine biodegradation rate of biodegradable resins.

[11] Use of 16-hydroxyhexadecanoic acid in the production of a marine biodegradable resin composition with an accelerated marine biodegradation rate.

[12] A method for producing an accelerator for accelerating the marine biodegradation rate of biodegradable resins, including formulating 16-hydroxyhexadecanoic acid.

[13] A method for producing a marine biodegradable resin composition with an accelerated marine biodegradation rate, including mixing a biodegradable resin composition and 16-hydroxyhexadecanoic acid.

Advantages of the Invention

[0009] According to the present invention, the marine biodegradation rate of biodegradable resins can be accelerated. That is, the present invention provides an accelerator for accelerating the marine biodegradation rate of biodegradable resins, a marine biodegradable resin composition with an accelerated marine biodegradation rate, a molded article formed from the marine biodegradable resin composition, a method for accelerating the biodegradation rate of biodegradable resins in a marine environment, a method for biodegrading biodegradable resins in a marine environment, and the like. That is, according to the present invention, by coexisting a biodegradable resin with a low marine biodegradation rate and 16-hydroxyhexadecanoic acid, the marine biodegradation rate of the biodegradable resin can be accelerated. Therefore, it is possible to inexpensively provide a composite material that maintains mechanical properties under normal use conditions but has enhanced biodegradability when it leaks into the environment after use and is placed in a situation with few microorganisms such as in the ocean.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described. <Marine Biodegradation Rate Accelerator> One aspect of the present invention relates to a marine biodegradation rate accelerator for biodegradable resins containing 16-hydroxyhexadecanoic acid (hereinafter, sometimes referred to as "the marine biodegradation rate accelerator of the present invention").

[0012] In the present invention, by bringing 16-hydroxyhexadecanoic acid into contact with a biodegradable resin, the biodegradation rate of the biodegradable resin in a marine environment such as seawater or the ocean can be accelerated. The marine biodegradation rate accelerator of the present invention can accelerate the biodegradation rate of a biodegradable resin in a marine environment, for example, by mixing the marine biodegradation rate accelerator of the present invention with a biodegradable resin, laminating the marine biodegradation rate accelerator of the present invention on a biodegradable resin, or the like, and bringing them into contact. Regarding the method of using the marine biodegradation rate accelerator of the present invention, such as the method of bringing the marine biodegradation rate accelerator of the present invention into contact with a biodegradable resin and the amount used, reference can be made to the matters described in the sections of <Marine biodegradable resin composition>, <Molded article>, and <Biodegradation rate acceleration method and biodegradation method> described later.

[0013] ≪Biodegradable resin≫ The "biodegradable resin" which is the target substance for accelerating the marine biodegradation rate of the marine biodegradation rate accelerator of the present invention is not particularly limited as long as it is a polymer biodegradable by biodegradable polymer-decomposing bacteria. Biodegradable resins include those derived from organisms and those obtained by chemical synthesis, and any of them can be used. Examples of biodegradable resins include, but are not limited to, polyester resins, natural polymers and their derivatives, etc. Polyester resins include, for example, aliphatic polyesters, aromatic polyesters, etc., natural polymers include, for example, cellulose, starch, etc., and derivatives of natural polymers include, for example, cellulose esters, cellulose ethers, cellulose ether esters, etc. and can be selected therefrom.

[0014] Aliphatic polyesters may be, for example, polylactic acid (PLA), polyhydroxyalkanoic acid (PHA), polyethylene succinate (PESu), polybutylene succinate (PBSu), polyethylene succinate adipate (PESA), polybutylene succinate adipate (PBSA), polycaprolactone (PCL), polybutylene succinate carbonate (PEC), a polylactic acid / polycaprolactone copolymer, a polylactic acid / polyether copolymer, etc.

[0015] Aromatic polyesters may be, for example, polybutylene adipate terephthalate (PBAT), polytetramethylene adipate terephthalate, polyethylene terephthalate succinate (CPE), etc.

[0016] Polyhydroxyalkanoic acid (PHA) may be, for example, a poly-3-hydroxyalkanoate resin containing 3-hydroxyalkanoate, specifically, it may be a poly-3-hydroxybutyrate (PHB) resin containing 3-hydroxybutyrate, more specifically, it may be poly-3-hydroxybutyrate (PHB), poly(3-hydroxybutyrate / 3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate / 3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate / 4-hydroxybutyrate), etc.

[0017] Cellulose esters may be, for example, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, etc. Cellulose ethers may be, for example, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, cyanoethyl cellulose, etc. Cellulose ether esters may be, for example, hydroxypropyl methyl cellulose acetate, hydroxypropyl methyl cellulose acetate succinate, etc. (In this specification, cellulose ether esters are intended to be included in the concepts of both cellulose ethers and cellulose esters.)

[0018] Although not limited, among these, preferably polyester resins are mentioned, more preferably aliphatic polyester resins are mentioned, still more preferably polyethylene succinate, polybutylene succinate, polyethylene succinate / adipate, polybutylene succinate / adipate are mentioned, and particularly preferably, polybutylene succinate, polybutylene succinate / adipate are mentioned. The biodegradable resin may contain one kind or two or more kinds. The biodegradable resin can be prepared, for example, by ordinary polymer preparation methods. It is also possible to use commercially available products.

[0019] The molecular weight of the biodegradable resin used in the present invention is not particularly limited as long as the effects of the present invention are not impaired. For example, in terms of the number average molecular weight (Mn), it may be 20,000 to 10,000,000. In terms of the weight average molecular weight (Mw), it may be 20,000 to 10,000,000. The molecular weight can be measured by gel permeation chromatography (GPC) or the like.

[0020] Here, the biodegradability of the biodegradable resin means the property that the biodegradable resin is cleaved and fragmented into low molecules by the action of hydrolytic enzymes of biodegradable polymer-decomposing bacteria and then mineralized. The biodegradability (marine biodegradability) of the biodegradable resin in the marine environment can be confirmed, for example, by immersing a sample in seawater and observing that the weight after the seawater immersion test decreases from the initial weight and the biochemical oxygen demand (BOD) during the test.

[0021] ≪16-Hydroxyhexadecanoic acid≫ The marine biodegradation rate accelerator of the present invention contains 16-hydroxyhexadecanoic acid as an active ingredient.

[0022] 16-Hydroxyhexadecanoic acid is an aliphatic hydroxycarboxylic acid having 16 carbon atoms, and it is also possible to use those synthesized by known chemical synthesis methods and purified as necessary, or commercially available products such as 16HHD manufactured by Sigma-Aldrich or Fujifilm Wako Pure Chemical Corporation.

[0023] The blending ratio of 16-hydroxyhexadecanoic acid in the marine biodegradation rate accelerator is not limited, but for example, it can be about 0.001 to 100% by weight, 0.01 to 90% by weight, 0.1 to 80% by weight, 1 to 70% by weight, 10 to 60% by weight, or 20 to 50% by weight based on the total amount of the marine biodegradation rate accelerator.

[0024] The marine biodegradation rate accelerator may be composed of the above 16-hydroxyhexadecanoic acid, but optionally, it may contain additives for formulation, such as solvents, excipients, stabilizers, etc. That is, the marine biodegradation rate accelerator can also be paraphrased as a "composition for promoting marine biodegradation rate". The additives can be used alone or in combination of two or more. Optionally, it may also contain a nutrient source necessary for the growth of biodegradable resin-degrading microorganisms.

[0025] The dosage form of the marine biodegradation rate accelerator is not particularly limited, and it may be in the form of powder, pellet, solid in film form, or dissolved or dispersed in a hydrophilic or lipophilic liquid, sol, or gel. The formulation of the marine biodegradation rate accelerator can be carried out based on conventional methods.

[0026] <Marine biodegradable resin composition> Another aspect of the present invention relates to a marine biodegradable resin composition (hereinafter sometimes referred to as "the marine biodegradable resin composition of the present invention") containing a biodegradable resin and the marine biodegradation rate accelerator of the present invention. Note that the matters described in the section of <Marine biodegradation rate accelerator> above are all applicable to the description of the marine biodegradable resin composition of the present invention.

[0027] The marine biodegradable resin composition of the present invention contains the above biodegradable resin and the marine biodegradation rate accelerator. Even if the marine biodegradation rate accelerator is in a small proportion with respect to the biodegradable resin, the biodegradability can be greatly promoted. Therefore, the biodegradability of the biodegradable resin can be improved or promoted without significantly impairing the mechanical properties, etc. of the biodegradable resin. Also, the biodegradability of the biodegradable resin can be controlled by the amount of the marine biodegradation rate accelerator used.

[0028] The blending ratio of the marine biodegradation rate accelerator in the marine biodegradable resin composition is not limited. For example, it may be 1 to 500 parts by weight, 10 to 100 parts by weight, or 1 to 50 parts by weight as 16-hydroxyhexadecanoic acid with respect to 100 parts by weight of the biodegradable resin.

[0029] The marine biodegradable resin composition may, if necessary, contain various additives commonly used in biodegradable resin compositions, such as plasticizers, stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), surfactants, lubricants, colorants, fillers, antistatic agents, silane coupling agents, dispersants, dispersion aids, release agents, etc. of the biodegradable resin. The additives can be used alone or in combination of two or more.

[0030] The marine biodegradable resin composition may be in the form of a mixture of a biodegradable resin and a marine biodegradation rate accelerator, or may be in a form in which the biodegradable resin and the marine biodegradation rate accelerator are kneaded and integrated (for example, in the form of powder, granules, or pellets).

[0031] As the form of the mixture of the biodegradable resin and the marine biodegradation rate accelerator, the marine biodegradation rate accelerator may be laminated on the biodegradable resin by film forming or coating on the surface of the biodegradable resin, etc. The lower limit value of the thickness of the laminated layer may be, for example, 0.75 μm or more, 1 μm or more, or 3 μm or more. The upper limit value may be, for example, 100 μm or less, 50 μm or less, or 10 μm or less.

[0032] The production of the marine biodegradable resin composition can be carried out based on conventional methods. For example, a coating liquid in which a marine biodegradation rate accelerator, a binder, etc. are dissolved or dispersed in a liquid such as water is used to form and laminate a film on one or both surfaces of the biodegradable resin by a lamination method. Specific examples include an extrusion lamination method in which a coating liquid melted from a T-die is extruded into a film shape and then cooled and pressure-bonded to the biodegradable resin laminated on a separately fed base material using a cooling roll, and a thermal lamination method in which a film formed by a previously prepared coating liquid is heated and pressure-bonded to the biodegradable resin laminated on a base material. Also, a method of forming by applying a coating liquid in which a marine biodegradation rate accelerator is dissolved or dispersed in a liquid such as water on one or both surfaces of the biodegradable resin, heating, drying, and forming a film can be mentioned.

[0033] As a form in which the biodegradable resin and the marine biodegradation rate accelerator are kneaded and integrated, the marine biodegradation rate accelerator may be in a form kneaded and integrated with the biodegradable resin or the like.

[0034] The production of the marine biodegradable resin composition can be carried out based on conventional methods. For example, at least the biodegradable resin and the marine biodegradation rate accelerator can be introduced into an extruder and melt-kneaded. In the melt-kneading process, the biodegradable resin, the marine biodegradation rate accelerator, and, if necessary, additives and the like may be individually introduced into the extruder, or each component may be mixed and then introduced into the extruder. The melt-kneading in the melt-kneading process can be carried out using, for example, an extruder (single-screw extruder, twin-screw extruder), a kneader, or the like.

[0035] The marine biodegradable resin composition can be produced in the same manner as the production method of a normal polymer composition, except that it contains a marine biodegradation rate accelerator together with the biodegradable resin.

[0036] <Molded article> Another aspect of the present invention relates to a molded article formed of the marine biodegradable resin composition of the present invention (hereinafter sometimes referred to as "the molded article of the present invention"). Note that all matters described in the sections of <marine biodegradation rate accelerator> and <marine biodegradable resin composition> are all applicable to the description of the molded article of the present invention.

[0037] The marine biodegradable resin composition of the present invention can be made into molded articles such as films, sheets, and the like, appliances and containers having shapes suitable for use, and non-woven fabrics by molding.

[0038] There is no particular limitation on the method for obtaining a film or sheet made of the marine biodegradable resin composition of the present invention, and it is formed into a film shape or a sheet shape by a known molding method. For example, methods of forming into a film shape or a sheet shape by a T-die molding method, an inflation molding method, a calendar molding method, a hot press molding method, etc. can be mentioned. Further, these films and sheets may be stretched in at least one direction. There is no particular limitation on the stretching method, and examples include a roll stretching method, a tenter method, an inflation method, etc.

[0039] There is no particular limitation on the method for obtaining a molded article having a shape suitable for use and made of the marine biodegradable resin composition of the present invention, and it can be manufactured by a known method. For example, methods such as performing extrusion molding or injection molding on a mold can be mentioned. The thickness of the molded article of the marine biodegradable resin composition of the present invention is preferably made thin in order to enhance its water disintegration property and biodegradability, but it can be freely adjusted so as to satisfy strength, flexibility, etc. The preferable thickness of the film is 5 to 300 μm, and more preferably 10 to 100 μm. The thickness of the sheet or the container-shaped molded article is preferably 0.1 to 5 mm, and more preferably 0.2 to 2 mm. Further, the tensile elastic modulus is not particularly limited in its value, but usually, those of 1200 MPa or less are preferable, and those of 600 MPa or less are more preferable. The tensile strength is not particularly limited in its value, but the range of 10 to 100 MPa is preferable, the range of 15 to 70 MPa is more preferable, and the range of 20 to 50 MPa is even more preferable.

[0040] There is no particular limitation on the method for obtaining the nonwoven fabric of the marine biodegradable resin composition of the present invention, and it is manufactured by a known method, for example, a dry method, a spunbond method, a meltblown method, a wet method, etc. That is, after spinning the marine biodegradable resin composition of the present invention, or a composition containing the marine biodegradable resin composition and an additive, a web is formed, and the web is bonded by a known method.

[0041] The molded article containing the marine biodegradable resin composition of the present invention is not particularly limited in its use, and can be used, for example, as a member (part) constituting a sanitary product, agricultural and horticultural materials, civil engineering and construction materials, fishing materials, etc. That is, it is possible to manufacture sanitary products, agricultural and horticultural materials, civil engineering and construction materials, fishing materials, etc. using a material containing the marine biodegradable resin composition of the present invention.

[0042] As a manufacturing method for sanitary products, agricultural and horticultural materials, civil engineering and construction materials, fishing materials, etc., it can be manufactured by molding a composition containing the marine biodegradable resin composition of the present invention into a desired shape, and further, the molded articles can be adhered and fixed to each other by known methods such as hot melt adhesion or thermal adhesion.

[0043] Examples of the sanitary products include disposable paper diapers, incontinence pads, sanitary napkins, etc. Examples of the agricultural and horticultural materials include mulch film, seedling pots, gardening tape, fruit cultivation bags, stakes, fumigation sheets, films for greenhouses, etc. Examples of the civil engineering and construction materials include vegetation nets, vegetation pots, three-dimensional net-like bodies, civil engineering fibers, stakes, heat insulating materials, etc. Examples of the fishing materials include fishing nets, aquaculture equipment, fishing tackle, mooring ropes, fenders, sea anchors, floating bodies, etc.

[0044] <Method for accelerating biodegradation rate and biodegradation method> Another aspect of the present invention relates to a method (hereinafter sometimes referred to as "the method for accelerating the biodegradation rate of the present invention") of contacting a biodegradable resin with the marine biodegradation rate accelerator of the present invention to accelerate the biodegradation rate of the biodegradable resin in a marine environment. In another aspect, it relates to a method (hereinafter sometimes referred to as "the biodegradation method of the present invention") of contacting a biodegradable resin with the marine biodegradation rate accelerator of the present invention to biodegrade the biodegradable resin in a marine environment. As described above, by bringing the biodegradable resin into contact with the marine biodegradation rate accelerator of the present invention, the biodegradation rate of the biodegradable resin in the marine environment can be accelerated, and the biodegradable resin can be biodegraded. The step of bringing the biodegradable resin in the biodegradation rate acceleration method and biodegradation method of the present invention into contact with the marine biodegradation rate accelerator of the present invention can be carried out under the conditions and methods described in the <marine biodegradation rate accelerator> and <marine biodegradable resin composition> of the present invention. That is, for example, by adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin (it may also be by adding, mixing, or blending the biodegradable resin to the marine biodegradation rate accelerator of the present invention), when the biodegradable resin is placed in the marine environment, the biodegradation of the biodegradable resin can be promoted, and the biodegradable resin can be biodegraded. That is, the biodegradation rate acceleration method of the present invention may be a method for promoting the biodegradation of a biodegradable resin in a marine environment, including, for example, the step of adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin. Also, the biodegradation method of the present invention may be a method for biodegrading a biodegradable resin in a marine environment, including, for example, the step of adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin.

[0045] As a form of adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin, the marine biodegradation rate accelerator may be formed into a film on the biodegradable resin, or may be laminated by being coated on the surface of the biodegradable resin, etc. Also, as a form of adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin, the marine biodegradation rate accelerator may be kneaded with the biodegradable resin to be integrated, etc. Also, as a form of adding, mixing, or blending the marine biodegradation rate accelerator of the present invention to the biodegradable resin, the biodegradable resin and the marine biodegradation rate accelerator may be brought into contact with each other during use.

[0046] Usage amount of the marine biodegradation rate accelerator in the biodegradation rate acceleration method and biodegradation method of the present invention Although not limited, for example, it can be applied in an amount of about 1 to 500 parts by weight, 10 to 100 parts by weight, or 30 to 50 parts by weight as 16-hydroxyhexadecanoic acid with respect to 100 parts by weight of the biodegradable resin.

[0047] Another aspect of the present invention may be a method for producing the marine biodegradable resin composition of the present invention, which includes, for example, a step of adding, mixing, or compounding the marine biodegradation rate accelerator of the present invention to the biodegradable resin.

[0048] Note that the matters described in the sections of <marine biodegradation rate accelerator>, <marine biodegradable resin composition>, and <molded article> are all applicable to the description of the biodegradation rate acceleration method and biodegradation method of the present invention.

[0049] Here, "accelerating the biodegradation rate of the biodegradable resin in the marine environment" means, although not limited, that compared with the biodegradation rate of the biodegradable resin without the addition of the marine biodegradation rate accelerator of the present invention in the marine environment, the biodegradation rate of the biodegradable resin added with the marine biodegradation rate accelerator of the present invention is increased. Although not limited, for example, the biodegradation rate of the biodegradable resin added with the marine biodegradation rate accelerator of the present invention is 1.25 times or more, 1.5 times or more, 2 times or more, or 5 times or more the biodegradation rate of the biodegradable resin without the addition of the marine biodegradation rate accelerator of the present invention. Whether the biodegradation rate of the biodegradable resin has increased can be confirmed by a decomposition test as shown in the following examples. For example, from the difference between the initial weight of the sample and the weight after the seawater immersion test, the weight loss amount is calculated, and using the weight loss rate obtained by dividing the weight loss amount by the surface area of the sample and the immersion period as an index, when the biodegradation rate of the biodegradable resin added with the marine biodegradation rate accelerator of the present invention is faster than that of the biodegradable resin without the addition of the marine biodegradation rate accelerator of the present invention, it can be determined that the biodegradation rate of the biodegradable resin has increased.

Examples

[0050] Hereinafter, the present invention will be specifically described by way of examples. However, these are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

[0051] <Experimental method> ≪Preparation of samples≫ Poly(butylene succinate-co-adipate) (PBSA) (Mw = 1.5×10 6 ) and poly(butylene succinate) (PBSu) (Mw = 1.8×10 6 ) were purchased from Mitsubishi Chemical Corporation. 16HHD was used which was purchased from Sigma-Aldrich and Fujifilm Wako Pure Chemical Corporation.

[0052] ≪Environmental samples≫ Seawater was collected from the Yokosuka Branch of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in Yokosuka City, Kanagawa Prefecture (N35°31’27.63”, E139°65’43.83”). Seafloor mud was collected from the Marine Science Station affiliated with the Graduate School of Integrative Life Sciences, Hiroshima University in Onomichi City, Hiroshima Prefecture (N34°21’54”, E133°13’0”).

[0053] ≪Biodegradation rate test≫ 10 wt / % of 16HHD was added to PBSA and PBSu respectively. Using MiniLab 3, they were kneaded at 150 °C and 50 rpm. As a comparative sample, the same operation was performed without adding anything to PBSA and PBSu. The strands after kneading were put into a stainless steel mold with a thickness of 0.5 mm and sandwiched with a polyimide film (Toray DuPont Co., Ltd., Kapton). After further sandwiching with stainless steel plates, using a press machine (Mini Test Press MP-SCH, TOYOSEIKI), it was pressed at 150 °C, 5 MPa for 1 min and 15 MPa for 1 min. After slow cooling, it was removed from the mold to obtain a film.

[0054] (Test in shallow sea) One piece of each film (2 cm × 2 cm) was placed in a polystyrene petri dish with a plurality of holes drilled in the upper and lower parts. They were placed one by one. The sides of the petri dishes were wrapped with vinyl chloride tape. These petri dishes were fixed to a nylon trical net with binding bands. Ropes were passed through both sides of the trical net, and concrete blocks were attached to the ends of the ropes. This was installed at a position 2 - 3 m above the seabed of the quay wall of JAMSTEC Yokosuka Headquarters (Natsushima-cho, Yokosuka City, Kanagawa Prefecture, N35°31’27.63”, E139°65’43.83”). The installation periods were from November 2019 to January - March 2020 for PBSA and from March to May - July 2020 for PBSu.

[0055] (Tests in the deep sea) Each film (4 cm × 4 cm) was placed one by one in a plastic container with many holes, protected by a polyethylene mesh (mesh 24#, opening 924 μm). The container was covered with a net and installed in the deep seabed off Misaki (N35°04.21’, E139°33.20’, water depth 757 m) and the deep - sea plain west of KEO (N32°34.79’, E143°46.15’, water depth 5502 m). The Shinkai 6500 was used for installation and recovery in the deep sea. The installation period was from June to November 2022.

[0056] (Tests in the water tank) Seawater (35 L) was put into a water tank (Reglass Flat F - 3050, Shougei Co., Ltd.) and circulated using an electric pump (Mega Power 2045, Jex Co., Ltd.). Each film (2 cm × 2 cm) was placed one by one in a bag (3 cm×3 cm) made of stainless - steel mesh (mesh size 90) and suspended from the upper part of the water tank with nylon tags. 0.175 g of ammonium chloride was added to the seawater in the water tank every two weeks. The test temperature was set at 20°C. The installation period was from December 2019 to January - March 2020.

[0057] (Tests using sterilized artificial seawater) Artificial seawater (200 mL) was prepared in accordance with ASTM D1141-98 and placed in a polypropylene bottle. The artificial seawater was sterilized using an autoclave (manufactured by Hirayama Seisakusho). A film (1 cm × 1 cm) wrapped with a polyethylene mesh that had been sterilized with methanol and washed with sterilized distilled water was immersed in the artificial seawater. The film was recovered every two weeks.

[0058] The number of tests was set to N = 5. Each recovered film was washed with methanol and distilled water, dried under reduced pressure, and then weighed. The weight loss rate of the film was calculated using the following formula from the weight loss amount, surface area, and immersion period of each film.

[0059]

Number

[0060] ≪Observation of Film Surface Morphology≫ The film was immersed in a 2.5% glutaraldehyde solution for 1 hour. This film was immersed in solutions (50, 60, 70, 80, 90, 99.5%) with sequentially changing ethanol concentrations for 20 minutes each to dehydrate it. Then, the film was immersed in tert-butyl alcohol for 1 hour and then freeze-dried. The film was gold-coated using a DII-29010SCTR Smart Coater (manufactured by JEOL Ltd.) and observed with a scanning electron microscope (JCM-7000 NeoScope (trademark), manufactured by JEOL Ltd.).

[0061] ≪BOD Biodegradability Test and TOC Test≫ In accordance with ASTM D6691-17, using a BOD tester OxiTOP (manufactured by WTW), each sample in seawater The biodegradability based on the BOD of the loop was measured. For 600 mL of seawater, 100 g of marine mud was added, and ultrasonic waves were irradiated for 10 seconds using an ultrasonic cleaner (manufactured by AS ONE Corporation). Then, it was filtered using qualitative filter paper (No. 2 manufactured by ADVANTEC) to prepare a marine mud extract. A medium was prepared by adding ammonium chloride (0.5 g / L), potassium dihydrogen phosphate (0.1 g / L), and an aqueous solution of allylthiourea (5 g / L, 200 μL) to the soil extract (200 mL). Media (200 mL), samples, and a stir bar were placed in a 250 mL Erlenmeyer flask. A carbon dioxide absorbent (manufactured by Yabashi Lime (registered trademark)-f, manufactured by Yabashi Kogyo Co., Ltd.) was installed at the upper part of the Erlenmeyer flask to absorb the carbon dioxide generated by the respiration of microorganisms. A BOD tester OxiTOP was attached and stirred in a constant temperature bath at 30 °C. A sample-free one was used as a negative control. Cellulose and PHBV were used as positive controls. The chemical composition of the sample was determined by performing elemental analysis using a carbon, hydrogen, and nitrogen simultaneous analyzer (manufactured by J-Science Lab Co., Ltd., MICRO CORDER JM 10). The BOD biodegradability was calculated by the following formula.

[0062]

Equation

[0063] Here, BOD b , BOD t , ThOD represent the BOD of the blank (15 minutes after medium preparation), the BOD of the test solution, and the theoretical oxygen demand, respectively.

[0064] ≪Measurement of DNA / RNA amount≫ The test solution after the BOD test was filtered using a membrane filter with a pore size of 0.45 μm manufactured by ADVANTEC to recover microorganisms. Using ZymoBIOMICS DNA / RNA Miniprep Kits, DNA / RNA was extracted from the membrane filter according to the product protocol. The concentration of DNA / RNA was measured using an ultra-micro spectrophotometer Nabi.

[0065] <Result> <<Biodegradation rate test in shallow sea>> Figure 1 shows the weight loss rates of each film installed in the coastal sea area (shallow sea). The addition of 16HHD increased the weight loss rate of PBSA. Also, the addition of 16HHD increased the weight loss rate of PBSu.

[0066] <<Biodegradation rate test in deep sea>> Figure 2 shows the weight loss rates of each film installed in the deep sea (Miura and KEO). The addition of 16HHD increased the weight loss rate of PBSA. Also, the addition of 16HHD increased the weight loss rate of PBSu.

[0067] <<Biodegradation rate test using sterilized artificial seawater>> The weight loss rates of each sample in sterilized artificial seawater are shown in Figures 3 and 4. In all samples, the weight loss rate in sterilized artificial seawater was smaller than the weight loss rate in the shallow sea or in the water tank. From this, it was suggested that the degradation of PBSA and PBSu added with 16HHD was caused by biological action.

[0068] <<Observation of film surface morphology>> Figures 5 and 6 show the SEM images of the surface of each film before and after the shallow sea immersion test. The surface of the film after seawater immersion became rough. Especially for PBSA and PBSu added with 16HHD, the surface roughness increased.

[0069] <<BOD biodegradability test and TOC test>> Figure 7 shows the BOD biodegradation degree curves of PBSA-based resin, PBSu-based resin, and each 16HHD-added resin, respectively. On the 90th day, PBSA and PBSu did not show a biodegradation degree. On the 90th day, PBSA + 16HHD showed a biodegradation degree of 80% or more, and PBSu + 16HHD showed a biodegradation degree of 90% or more.

[0070] Table 1 shows the results of the TOC test of the samples after 90 days of the BOD test of the 16HHD-added resin. By comparing the TOC value of the Blank solution after the BOD test without adding the sample with the TOC value of the sample, the proportion of the carbon amount derived from the resin in the BOD test solution was calculated, and all were less than 1%. From this, it was shown that the 16HHD-added resin was completely mineralized.

[0071]

Table 1

[0072] ≪DNA / RNA Measurement≫ Figure 8 shows the amounts of DNA / RNA in the BOD test systems of the PBSA-based resin and the PBSu-based resin, respectively. In PBSA + 16HHD and PBSu + 16HHD after the test, an increase in the amount of DNA / RNA was observed compared to before the test. From this, it was suggested that the addition of 16HHD to the resin caused the resin to be metabolized by microorganisms and the amount of microorganisms in the system increased.

[0073] From the above results, it was found that by bringing 16HHD into contact with the biodegradable resin, the marine biodegradation rate of the biodegradable resin is promoted.

Industrial Applicability

[0074] According to the method of the present invention, it is possible to accelerate the marine biodegradability rate of the biodegradable resin by bringing 16-hydroxyhexadecanoic acid into contact therewith. By bringing the biodegradable resin into contact with 16-hydroxyhexadecanoic acid, it is considered that the biodegradable resin-degrading microorganisms accumulate on the surface of the biodegradable resin, and the marine biodegradation rate of the biodegradable resin is promoted. The present invention can be preferably applied to materials that are expected to be used and flow out in the environment, such as fishing gear, fishing tackle, agricultural multifilms, and coating materials for fertilizers, although it can be used in various fields as a biodegradable resin product.

Claims

1. An accelerator for the marine biodegradation rate of a biodegradable resin, comprising 16-hydroxyhexadecanoic acid.

2. The accelerator for the marine biodegradation rate according to Claim 1, wherein the biodegradable resin is a polyester resin.

3. The accelerator for the marine biodegradation rate according to Claim 1, wherein the biodegradable resin is one or more selected from polybutylene succinate and polybutylene succinate / adipate.

4. A biodegradable resin, and the accelerator for the marine biodegradation rate according to any one of Claims 1 to 3, comprising a marine biodegradable resin composition with an accelerated marine biodegradation rate.

5. A molded article formed from the marine biodegradable resin composition according to Claim 4.

6. A method for accelerating the biodegradation rate of a biodegradable resin in a marine environment by bringing the biodegradable resin into contact with the accelerator for the marine biodegradation rate according to any one of Claims 1 to 3.

7. A method for biodegrading a biodegradable resin in a marine environment by bringing the biodegradable resin into contact with the accelerator for the marine biodegradation rate according to any one of Claims 1 to 3.

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