Paramylon-based resin, its manufacturing method, molding resin composition, and molded body

Abstract

[Problem] To provide a method whereby a paramylon-based resin having improved mechanical properties can be easily produced at low cost. [Solution] A method for producing a paramylon-based resin which comprises: a step in which paramylon having a weight-average molecular weight of 220,000-500,000 is dispersed in a solvent comprising N-methylpyrrolidone and / or pyridine; a step in which a short-chain acylating agent, which is acetyl chloride and / or propionyl chloride, and a long-chain acylating agent, which is a chloride of a saturated fatty acid having 12 or more carbon atoms, are added to the paramylon dispersion to thereby acylate hydroxy groups of the paramylon; and a step in which a paramylon-based resin obtained in the acylation step is collected. In the acylation step, the weight ratio among the dry weight A of the paramylon, the overall weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent, (B+C) / A, is 17.5-60.0.

Description

[Technical Field]

[0001] The present invention relates to a paramylon-based resin made from paramylon as a raw material, a method for producing the same, a molding resin composition, and a molded article. [Background technology]

[0002] In recent years, the development of bioplastics made from plant materials has been progressing from the perspective of reducing environmental impact. Conventional bioplastics, such as polylactic acid, polyhydroxyalkanoates, and modified starch, are all made from starch-based materials, i.e., edible parts of plants. However, concerns about future food shortages have led to calls for the development of bioplastics made from inedible plant materials.

[0003] As for non-edible plant raw materials, attention is being focused on woody biomass such as wood and vegetation, as well as algal biomass. Algae, in particular, can be cultivated even on land unsuitable for farming, do not compete with food production, and can be cultivated repeatedly using CO2, nutrients, and sunlight, making them sustainable alternatives to fossil fuels. Furthermore, algae can also be used to efficiently produce useful organic components, particularly long-chain fatty acids and polysaccharides, which are effective as key components of bioplastics.

[0004] One such algae-derived polysaccharide known is β-1,3 glucan (paramylon). Paramylon is a polysaccharide in which glucose molecules are linked in a linear chain using only β-1,3 bonds. It has strong intermolecular forces due to hydrogen bonds derived from hydroxyl groups, and therefore does not exhibit thermoplasticity. For this reason, bioplastics that use paramylon are given thermoplasticity by adding various substituents to paramylon.

[0005] For example, Patent Document 1 describes a paramylon derivative in which paramylon is acylated using an acylating agent, which is a reaction product of a short-chain carboxylic acid and a short-chain carboxylic anhydride, and Patent Document 2 describes a paramylon derivative in which the hydroxyl groups of paramylon are substituted with long-chain acyl groups. However, these paramylon derivatives are substituted only with short-chain acyl groups or only with long-chain acyl groups, and therefore have insufficient thermoplastic and mechanical properties.

[0006] Patent Document 3 describes a method for producing paramylon derivatives substituted with long-chain acyl groups and short-chain acyl groups, in which a chloride of a long-chain aliphatic carboxylic acid having 13 or more carbon atoms is added to paramylon dissolved in a solvent to acylate some of the hydroxyl groups of the paramylon, and then acetic anhydride or propionic anhydride is added to acylate the remaining hydroxyl groups.

[0007] However, the above-mentioned method requires complicated procedures and a large amount of solvent to dissolve the paramylon, and therefore, a more improved production method is needed from the standpoint of cost and resource circulation. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-193667 [Patent Document 2] Japanese Patent Application Publication No. 2018-154723 [Patent Document 3] Patent No. 6029155 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a method for easily producing paramylon-based resin with improved mechanical properties at low cost. [Means for solving the problem]

[0010] According to one aspect of the present invention, A step of dispersing paramylon having a weight average molecular weight of 220,000 to 500,000 in a solvent containing N-methylpyrrolidone and / or pyridine; a step of adding a short-chain acylating agent, which is acetyl chloride and / or propionyl chloride, and a long-chain acylating agent, which is an acid chloride of a saturated fatty acid having 12 or more carbon atoms, to the paramylon dispersion to acylate the hydroxy groups of the paramylon; and A step of recovering the paramylon-based resin obtained by the acylation step. Including, A method for producing a paramylon-based resin is provided, wherein in the acylation step, the weight ratio (B+C) / A of the dry weight A of paramylon, the total weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent is 17.5 to 60.0. [Effects of the Invention]

[0011] According to the present invention, a method can be provided that can easily and inexpensively produce paramylon-based resins with improved mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] [1] Manufacturing method for paramylon resin The method for producing a paramylon-based resin of the present invention comprises the steps of: A step of dispersing paramylon having a weight average molecular weight of 220,000 to 500,000 in a solvent containing N-methylpyrrolidone and / or pyridine; a step of adding a short-chain acylating agent, which is acetyl chloride and / or propionyl chloride, and a long-chain acylating agent, which is an acid chloride of a saturated fatty acid having 12 or more carbon atoms, to the paramylon dispersion to acylate the hydroxy groups of the paramylon; and A step of recovering the paramylon-based resin obtained by the acylation step. Including, In the acylation step, the weight ratio (B+C) / A of the dry weight A of paramylon, the total weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent is 17.5 to 60.0.

[0013] [Dispersion process] (paramylon) Paramylon is a linear polymer formed by the polymerization of β-D-glucose molecules (β-D-glucopyranose) via β(1→3) glycosidic bonds, as shown in the following formula (1) (where n is a natural number). Each glucose unit that makes up paramylon has three hydroxyl groups.

[0014] [ka]

[0015] The weight-average molecular weight of the paramylon used in the method for producing a paramylon-based resin of the present invention, as measured by gel permeation chromatography (GPC), is 220,000 to 500,000, preferably 225,000 to 470,000, and more preferably 230,000 to 440,000.

[0016] (GPC measurement conditions for paramylon) Column: PLgel 20 μm MIXED-A (product name, manufactured by Agilent Technologies, Inc.) Eluent: Dimethylacetamide (DMAc) solution (0.1M LiCl) Flow rate: 0.5mL / min Detector: RI (differential refractive index) (Tosoh Corporation RI-71 type 201 (16X)) Temperature: 23.0℃ Standard sample: Pullulan standard

[0017] The dispersion step in the present invention involves dispersing paramylon in a solvent. This step involves an activation treatment to increase the reactivity of paramylon. The activation treatment involves contacting paramylon with a solvent to swell the paramylon. This treatment facilitates the penetration of reactants and catalysts between the paramylon molecular chains, thereby enhancing the reactivity of paramylon. The temperature of the dispersion step can be appropriately set within a range of, for example, 0 to 100°C. From the viewpoints of activation efficiency and reduced energy costs, a temperature of 10 to 40°C is preferred, with 15 to 35°C being more preferred. The duration of the dispersion step can be appropriately set within a range of, for example, 3 to 72 hours. From the viewpoints of sufficient activation and reduced processing time, a temperature of 5 to 48 hours is preferred, with 7 to 24 hours being more preferred. In the method of the present invention, paramylon does not need to be completely dissolved in the solvent; it is sufficient to disperse it, allowing for a reduced amount of solvent to be used. Generally, when using paramylon with a high molecular weight, a small amount of solvent can increase the viscosity of the reaction solution, leading to an inhomogeneous reaction and potentially reduced physical properties of the product. Alternatively, a method of pre-treating paramylon by hydrolyzing it with an acid or base to adjust its molecular weight is conceivable. However, the manufacturing method of the present invention does not require such a step of hydrolyzing paramylon with an acid or base.

[0018] Paramylon may be mixed with similar structures, such as cellulose, chitin, chitosan, hemicellulose, xylan, glucomannan, curdlan, etc. When such similar structures are mixed, the content of the similar structures is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, of the total mixture.

[0019] (solvent) The solvent used in the acylation step of the present invention contains N-methylpyrrolidone and / or pyridine. The solvent preferably contains 90% by weight or more of N-methylpyrrolidone and / or pyridine in total, and more preferably consists of N-methylpyrrolidone and pyridine. Pyridine acts as an acid scavenger and has the effect of accelerating the esterification reaction, so it is preferable to contain pyridine. The amount of pyridine is preferably 0.1 mol or more, more preferably 0.3 mol or more, and particularly preferably 0.5 mol or more, of the total weight of the short-chain acylating agent and the long-chain acylating agent.

[0020] [Acylation step] The acylation process in the present invention is a process in which short-chain acyl groups (acetyl groups and / or propionyl groups) and long-chain acyl groups (saturated aliphatic acyl groups with 12 or more carbon atoms) are simultaneously introduced into paramylon using these hydroxy groups.

[0021] (short-chain acylating agent) The short-chain acylating agent is acetyl chloride and / or propionyl chloride, and has at least one functional group capable of reacting with a hydroxy group in paramylon. It is more preferable that the short-chain acylating agent is propionyl chloride alone.

[0022] (long-chain acylating agent) The long-chain acylating agent is an acid halide of a saturated fatty acid having 12 or more carbon atoms and has at least one functional group capable of reacting with the hydroxyl group in paramylon. Specific examples of saturated fatty acids having 12 or more carbon atoms include lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, and melissic acid. Myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid are preferred, with stearic acid being particularly preferred. Furthermore, from the perspective of environmental friendliness, saturated fatty acids derived from natural sources are preferred. The long-chain acylating agent may be used alone or in combination.

[0023] By reacting the hydroxyl groups in paramylon with a short-chain acylating agent and a long-chain acylating agent, short-chain acyl groups and long-chain acyl groups can be introduced into paramylon. The short-chain organic group of the short-chain acyl group and the long-chain organic group of the long-chain acyl group can be bonded to the pyranose ring of paramylon via an ester bond.

[0024] [ka]

[0025] In the acylation step of the present invention, the weight ratio (B+C) / A, where A is the dry weight of paramylon, B is the total weight of the solvent, and C is the total weight of the short-chain acylating agent and the long-chain acylating agent, is 17.5 to 60.0, preferably 18.0 to 50.0, and particularly preferably 18.0 to 40.0. If the weight ratio (B+C) / A is less than 17.5, the reaction will be uneven, and if it exceeds 60.0, it is undesirable from the standpoints of cost and resource recycling.

[0026] In the acylation step of the present invention, the weight ratio B / C, where C is the total weight of the short-chain acylating agent and the long-chain acylating agent and B is the total weight of the solvent, is preferably 1.0 to 25.0, more preferably 2.0 to 15.0, and particularly preferably 3.0 to 12.0. If the weight ratio B / C is less than 1.0 or exceeds 25.0, the reaction may become non-uniform, which is undesirable from the viewpoints of cost and resource recycling.

[0027] In the acylation step, when the acylating agents (short-chain acylating agent and long-chain acylating agent) are added to the solvent containing dispersed paramylon, the solvent temperature is preferably maintained between -30°C and 30°C, more preferably between -10°C and 20°C. At temperatures above 30°C, the highly reactive short-chain acylating agent reacts preferentially with paramylon over the long-chain acylating agent, resulting in an inhomogeneous reaction and reduced physical properties of the paramylon ester. Furthermore, after adding the acylating agent, the reaction temperature between the acylating agent and paramylon is preferably 50°C to 100°C, more preferably 75°C to 95°C. The reaction time can be appropriately set according to the desired degree of substitution. The reaction time can be set between 2 and 10 hours, preferably between 3 and 6 hours. A sufficiently high reaction temperature increases the reaction rate, allowing the acylation reaction to be completed in a relatively short time, thereby improving reaction efficiency. Furthermore, maintaining the reaction temperature within the above range prevents a decrease in the molecular weight of paramylon due to heating.

[0028] [Recovery process] The paramylon-based resin (product) into which short-chain acyl groups and long-chain acyl groups have been introduced in the acylation step can be recovered from the reaction solution by a conventional method, and the method is not limited thereto. If the product is not dissolved in the reaction solution, a recovery method in which the reaction solution and the product are subjected to solid-liquid separation is preferred from the viewpoint of production energy. If the product dissolves in or has an affinity with the reaction solution, making solid-liquid separation difficult, the reaction solution can be distilled off and the product recovered as a residue. Alternatively, a poor solvent for the product can be added to the reaction solution, and the precipitated product can be recovered by solid-liquid separation.

[0029] When components other than the product, such as the solvent, are distilled off from the reaction solution, the distillation can be stopped when the product precipitates, and then the remaining reaction solution and the precipitated product can be subjected to solid-liquid separation to recover the product.

[0030] Examples of solid-liquid separation methods include filtration (natural filtration, reduced pressure filtration, pressure filtration, centrifugal filtration, and hot filtration of these), natural settling / floating, liquid separation, centrifugal separation, squeezing, etc., and these may be used in appropriate combinations.

[0031] The product (paramylon-based resin) dissolved in the filtrate after solid-liquid separation can be precipitated by adding a poor solvent for the product and then recovered by further solid-liquid separation. The solid content (paramylon-based resin) recovered from the reaction solution can be washed as necessary and dried by a conventional method.

[0032] [2] Paramylon resin The paramylon-based resin of the present invention is a paramylon-based resin in which at least some of the hydrogen atoms of the hydroxy groups of paramylon having a weight-average molecular weight of 220,000 to 500,000 are substituted with saturated aliphatic acyl groups having 12 or more carbon atoms and acetyl groups and / or propionyl groups, and in which short-chain acyl groups and long-chain acyl groups are introduced into the paramylon by utilizing the hydroxy groups of the paramylon.

[0033] The short-chain acyl group is an acyl group derived from a short-chain acylating agent that is introduced to replace the hydrogen atom of a hydroxy group in paramylon. Introducing a short-chain acyl group into paramylon reduces the intermolecular forces (intermolecular bonds) of paramylon, improving mechanical properties such as elastic modulus, chemical resistance, and surface hardness. The short-chain acyl group is an acetyl group and / or a propionyl group, and propionyl groups alone are particularly preferred.

[0034] Degree of substitution by short-chain acyl groups (DS Sh ), that is, the average number of hydroxyl groups substituted with short-chain acyl groups (acetyl groups and / or propionyl groups) per glucose unit of paramylon (hydroxyl group substitution degree) is not particularly limited, but is preferably in the range of 1.5 to 2.5. In order to fully obtain the effect of introducing short-chain components, DS SH is more preferably 1.8 or more, and particularly preferably 1.9 or more. In order to obtain the effect of introducing short chain components while fully obtaining the effect of long chain components, DS Sh is more preferably 2.4 or less, particularly preferably 2.3 or less.

[0035] Long-chain acyl groups are acyl groups derived from long-chain acylating agents that are introduced into paramylon to replace hydrogen atoms in hydroxyl groups. Introducing long-chain acyl groups into paramylon can modify its properties, improving, for example, its water resistance, thermoplasticity, and mechanical properties. The long-chain acyl groups are saturated aliphatic acyl groups with 12 or more carbon atoms, preferably saturated aliphatic acyl groups with 12 to 22 carbon atoms, more preferably dodecanoyl (C12), tetradecanoyl (C14), hexadecanoyl (C16), octadecanoyl (C18), icosanoyl (C20), or docosanoyl (C22), with octadecanoyl (C18) being particularly preferred. These long-chain acyl groups may be of one type or two or more types.

[0036] Degree of substitution by long-chain acyl groups (DS Lo ), i.e., the average number of hydroxyl groups substituted with long-chain acyl groups (saturated aliphatic acyl groups having 12 or more carbon atoms) per glucose unit of paramylon (degree of hydroxyl group substitution) is not particularly limited, but is preferably in the range of 0.1 to 0.8, more preferably in the range of 0.2 to 0.7, and particularly preferably in the range of 0.3 to 0.6. Introduction of long-chain acyl groups can improve thermoplasticity and water resistance, and having an appropriate ratio of long-chain acyl groups to short-chain acyl groups can improve mechanical properties such as tensile strength and elastic modulus.

[0037] [3] Resin composition for molding The paramylon-based resin of the present invention can be used as a base resin for molding resin compositions by adding additives according to the desired properties. Here, the term "base resin" refers to the main component of the molding resin composition, and means that other components can be contained within a range that does not interfere with the function of the main component. While the content of the main component is not particularly specified, it encompasses cases in which the main component accounts for 50% by mass or more of the composition, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0038] The molding resin composition of the present invention can be applied with various additives used in ordinary thermoplastic resins. For example, the addition of a plasticizer can further improve thermoplasticity and elongation at break. Examples of such plasticizers include phthalate esters such as dibutyl phthalate, diaryl phthalate, diethyl phthalate, dimethyl phthalate, di-2-methoxyethyl phthalate, ethylphthalylethyl glycolate, and methylphthalylethyl glycolate; tartaric acid esters such as dibutyl tartrate; adipic acid esters such as dioctyl adipate and diisononyl adipate; polyhydric alcohol esters such as triacetin, diacetylglycerin, tripropionitrile glycerin, and glycerin monostearate; phosphate esters such as triethyl phosphate, triphenyl phosphate, and tricresyl phosphate; dibutyl adipate, dioctyl adipate, Examples of suitable additives include dibasic fatty acid esters such as dibutyl azelate, dioctyl azelate, and dioctyl sebacate; citric acid esters such as triethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate; epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; castor oil and its derivatives; benzoic acid esters such as ethyl O-benzoylbenzoate; aliphatic dicarboxylic acid esters such as sebacate and azelaate; unsaturated dicarboxylic acid esters such as maleate; and N-ethyltoluenesulfonamide, triacetin, O-cresyl p-toluenesulfonate, and tripropionin. Adding plasticizers such as dioctyl adipate, benzyl 2-butoxyethoxyethyl adipate, tricresyl phosphate, diphenylcresyl phosphate, and diphenyloctyl phosphate not only improves thermoplasticity and elongation at break, but also impact resistance.

[0039] Other plasticizers include cyclohexanedicarboxylic acid esters such as dihexyl cyclohexanedicarboxylate, dioctyl cyclohexanedicarboxylate, and di-2-methyloctyl cyclohexanedicarboxylate; trimellitic acid esters such as dihexyl trimellitate, diethylhexyl trimellitate, and dioctyl trimellitate; and pyromellitic acid esters such as dihexyl pyromellitate, diethylhexyl pyromellitate, and dioctyl pyromellitate.

[0040] If necessary, inorganic or organic granular or fibrous fillers can be added to the molding resin composition of the present invention, which can further improve the strength and rigidity of the composition. Examples of fillers include mineral particles (talc, mica, calcined silica earth, kaolin, sericite, bentonite, smectite, clay, silica, quartz powder, glass beads, glass powder, glass flakes, milled fiber, wollastonite (or wollastonite), etc.), boron-containing compounds (boron nitride, boron carbide, titanium boride, etc.), metal carbonates (magnesium carbonate, heavy calcium carbonate, light calcium carbonate, etc.), metal silicates (calcium silicate, aluminum silicate, magnesium silicate, magnesium aluminosilicate, etc.), metal oxides (magnesium oxide, etc.), metal hydroxides (aluminum hydroxide, calcium hydroxide, magnesium hydroxide, etc.), metal sulfates (calcium sulfate, barium sulfate, etc.), metal carbides (silicon carbide, aluminum carbide, titanium carbide, etc.), metal nitrides (aluminum nitride, silicon nitride, titanium nitride, etc.), white carbon, and various metal foils. Examples of fibrous fillers include organic fibers (natural fibers, paper, etc.), inorganic fibers (glass fibers, asbestos fibers, carbon fibers, silica fibers, silica-alumina fibers, wollastonite, zirconia fibers, potassium titanate fibers, etc.), metal fibers, etc. These fillers can be used alone or in combination.

[0041] A flame retardant can be added to the molding resin composition of the present invention as needed. Addition of a flame retardant can impart flame retardancy. Examples of flame retardants include metal hydrates such as magnesium hydroxide, aluminum hydroxide, and hydrotalcite, basic magnesium carbonate, calcium carbonate, silica, alumina, talc, clay, zeolite, bromine-based flame retardants, antimony trioxide, phosphate-based flame retardants (e.g., aromatic phosphate esters, aromatic condensed phosphate esters), and compounds containing phosphorus and nitrogen (phosphazene compounds). These flame retardants can be used alone or in combination.

[0042] There are no particular limitations on the method for producing the molding resin composition of the present invention in which various additives have been added to the paramylon-based resin, and the composition can be produced, for example, by melt-mixing the various additives and the paramylon-based resin by hand mixing or in a known compounding device such as a tumbler mixer, ribbon blender, single-screw or multi-screw extruder, kneader, or kneading roll, and then granulating the composition into an appropriate shape as necessary. Another suitable production method involves mixing the various additives and the paramylon-based resin dispersed in a solvent such as an organic solvent, adding a solidification solvent as necessary to obtain a mixed composition of the various additives and the paramylon-based resin, and then evaporating the solvent.

[0043] [4] Molded body The molded article of the present invention is produced by molding a moldable resin composition using a paramylon-based resin as a base resin, using methods such as extrusion molding, injection molding, and blow molding.

[0044] The Izod impact strength of the molded product of the present invention is 5.0 kJ / m 2 or more, 7.0 kJ / m 2 It is preferable that the concentration is 8.0 kJ / m or more. 2 The MFR (melt flow rate at 210°C and a load of 5 kg) of the molded article of the present invention is 5.0 g / 10 min or more, preferably 7.0 g / 10 min or more, and particularly preferably 8.0 g / 10 min or more.

[0045] The use of the molded article of the present invention is not particularly limited, but it is suitable for example as a molded article such as a housing for an exterior of an electronic device. [Example]

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Synthesis of paramylon resin (paramylon propionate stearate)] (Synthesis Example 1) (1) Paramylon (Wako Pure Chemical Industries, Ltd., weight-average molecular weight: 239,000) was placed in a sample bottle and dried for 5 hours in a vacuum dryer set at 105°C. 9.1 g of dried paramylon was dispersed in a mixed solvent of 122.8 g (119.6 mL) of N-methylpyrrolidone and 16.3 g (16.6 mL) of pyridine, and the mixture was stirred overnight at room temperature under a nitrogen atmosphere. (2) After cooling the paramylon dispersion liquid (1) to -4°C, 8.5 g (28.0 mmol) of stearoyl chloride and 15.5 g (168 mmol) of propionyl chloride that had been mixed in advance were added to the paramylon dispersion liquid (1) while maintaining the temperature below 10°C, and the mixture was heated to 90°C and then stirred for 4 hours while heating. (3) The reaction solution was then cooled to 65°C, 58 mL of methanol was added dropwise, and the mixture was stirred for approximately 30 minutes. 13 mL of water was then added to precipitate the product. The product was collected by suction filtration, washed five times with 54 mL of a methanol / water mixture (9 / 1 v / v), and vacuum dried at 105°C for 5 hours to obtain a paramylon-based resin (yield: 19.2 g, 90%).

[0047] (Synthesis Example 2) Using 4.2 g of dried paramylon, 54.1 g (52.7 mL) of N-methylpyrrolidone, 7.2 g (7.3 mL) of pyridine, 10.3 g (34.0 mmol) of stearoyl chloride, and 5.6 g (60.5 mmol) of propionyl chloride, a paramylon-based resin was obtained in the same manner as in Synthesis Example 1 (yield: 7.1 g (79%)).

[0048] (Synthesis Example 3) Using 5.0 g of dried paramylon, 128.6 g (125.2 mL) of N-methylpyrrolidone, 17.0 g (17.3 mL) of pyridine, 5.3 g (17.6 mmol) of stearoyl chloride, and 8.1 g (87.9 mmol) of propionyl chloride, a paramylon-based resin was obtained in the same manner as in Synthesis Example 1 (yield: 9.2 g (79%)).

[0049] (Synthesis Example 4) Using 4.2 g of dried paramylon, 54.1 g (52.7 mL) of N-methylpyrrolidone, 7.2 g (7.3 mL) of pyridine, 3.7 g (12.3 mmol) of stearoyl chloride, and 6.8 g (73.9 mmol) of propionyl chloride, a paramylon-based resin was obtained in the same manner as in Synthesis Example 1 (yield: 7.5 g (86%)).

[0050] The paramylon-based resins obtained in Synthesis Examples 1 to 4 were measured and evaluated as follows. The results are shown in Table 1.

[0051] [Measurement of glass transition temperature (Tg)] The glass transition temperature was determined by differential scanning calorimetry (DSC) under the following conditions. The measuring equipment used was a Seiko Instruments EXSTAR2000 and DSC6200. The paramylon-based resin was heated from 20°C to 200°C at 10°C / min, and then rapidly cooled from 200°C to -30°C at 50°C / min. The glass transition temperature (Tg) of the paramylon-based resin was then measured when the temperature was raised from -30°C to 200°C at 20°C / min.

[0052] [Preparation of molded body] Using an injection molder (HAAKE MiniJet II, manufactured by Thermo Electron Corporation), molded bodies measuring 2.4 mm in thickness, 12.4 mm in width, and 80 mm in length were fabricated from the paramylon-based resin obtained above. The molding conditions were as follows: cylinder temperature of the molding machine was 200°C (Synthesis Examples 1 and 3) or 210°C (Synthesis Examples 2 and 4), mold temperature was 65°C, injection pressure was 1200 bar (120 MPa) for 5 seconds, and dwell pressure was 600 bar (60 MPa) for 20 seconds.

[0053] [Measurement of flexural strength, flexural modulus, and flexural strain at break] The obtained molded article was subjected to a bending test in accordance with JIS K7171 to measure the bending strength, bending modulus, and breaking strain.

[0054] [Measurement of Izod impact strength] The notched Izod impact strength of the obtained molded article was measured under the conditions specified in JIS K 7110. The obtained data was evaluated according to the following criteria. (Izod impact strength evaluation criteria) ○: 5.0 kJ / m 2 End ×:5.0kJ / m 2 less than

[0055] [Measurement of fluidity (melt flow rate (MFR))] The MFR of the obtained molded body was measured using a high-speed flow tester (Shimadzu Corporation, product name: CFT-500D) under the conditions of 210°C temperature, 5 kg load, die 2 mmφ x 10 mm (hole diameter 2 mm, hole length 10 mm), and 2 minutes of preheating (the time from filling the cylinder with the sample and inserting the piston to applying the load) in accordance with JIS 7210: 1990. The obtained data were evaluated according to the following criteria. (MFR evaluation criteria) ○: 5.0g / 10min or more ×: Less than 5.0g / 10min

[0056] [Table 1]

[0057] The results of various evaluations are shown in Table 1. In Synthesis Examples 1 to 3, where the weight ratio (B+C) / A of the dry weight of paramylon (A), the total weight of the solvent (B), and the total weight of the short-chain acylating agent and the long-chain acylating agent (C) was 18.0 to 60.0, the reaction proceeded uniformly, and the IZOD impact strength and heat flowability (MFR) were good.

[0058] In contrast, in Synthesis Example 4, where the weight ratio (B+C) / A of the dry weight A of paramylon, the total weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent was less than 18.0, the reaction was heterogeneous (lumps formed on the flask, making it impossible to stir), and the results were poor in breaking strain, IZOD impact strength, and thermal fluidity (MFR).

[0059] Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to the above-described embodiments and examples. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0060] (Appendix 1) A step of dispersing paramylon having a weight average molecular weight of 220,000 to 500,000 in a solvent containing N-methylpyrrolidone and / or pyridine; a step of adding a short-chain acylating agent, which is acetyl chloride and / or propionyl chloride, and a long-chain acylating agent, which is an acid chloride of a saturated fatty acid having 12 or more carbon atoms, to the paramylon dispersion to acylate the hydroxy groups of the paramylon; and A step of recovering the paramylon-based resin obtained by the acylation step. Including, A method for producing a paramylon-based resin, wherein in the acylation step, the weight ratio (B+C) / A of the dry weight A of paramylon, the total weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent is 17.5 to 60.0. (Appendix 2) The method according to Appendix 1, wherein a weight ratio B / C of the total weight B of the solvent to the total weight C of the short-chain acylating agent and the long-chain acylating agent is 1.0 to 25.0. (Appendix 3) The method according to any of the preceding claims, which does not substantially include a step of hydrolyzing paramylon with an acid or a base. (Appendix 4) 10. The method of any of the preceding statements, wherein the long-chain acylating agent is an acid chloride of at least one fatty acid selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. (Appendix 5) A paramylon-based resin in which at least some of the hydrogen atoms of the hydroxy groups of paramylon having a weight-average molecular weight of 220,000 to 500,000 are substituted with saturated aliphatic acyl groups having 12 or more carbon atoms and acetyl groups and / or propionyl groups. (Appendix 6) A molding resin composition comprising the paramylon-based resin described in Appendix 5. (Appendix 7) A molded article formed using the molding resin composition according to Appendix 6. (Appendix 8) Izod impact strength 5.0kJ / m 2 That's all, 8. The molded article according to claim 7, having an MFR (melt flow rate at 210°C and a load of 5 kg) of 5.0 g / 10 min or more.

Claims

1. A step of dispersing paramylon having a weight average molecular weight of 220,000 to 500,000 in a solvent containing N-methylpyrrolidone and / or pyridine; a step of adding a short-chain acylating agent, which is acetyl chloride and / or propionyl chloride, and a long-chain acylating agent, which is an acid chloride of a saturated fatty acid having 12 or more carbon atoms, to the paramylon dispersion to acylate the hydroxy groups of the paramylon; and A step of recovering the paramylon-based resin obtained by the acylation step. Including, A method for producing a paramylon-based resin, wherein in the acylation step, the weight ratio (B+C) / A of the dry weight A of paramylon, the total weight B of the solvent, and the total weight C of the short-chain acylating agent and the long-chain acylating agent is 18.4 to 60.

0.

2. 2. The method according to claim 1, wherein in the acylation step, a weight ratio B / C of the total weight B of the solvent to the total weight C of the short-chain acylating agent and the long-chain acylating agent is 1.0 to 25.

0.

3. The method according to claim 1 or 2, which does not include a step of hydrolyzing paramylon with an acid or a base.

4. 3. The method of claim 1 or 2, wherein the long-chain acylating agent is an acid chloride of at least one fatty acid selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid.

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