Composite resin molded body having sustained drug release properties and its manufacturing method

Abstract

To provide a composite resin molding that has high elastic modulus, and sustained release properties of medicine.SOLUTION: A composite resin molding contains main agent resin and a plurality of fibrous fillers dispersed in the main agent resin, where the fibrous fillers contain volatile medicine. When the composite resin molding is 100 mass%, the content of fibrous filler containing medicine is 10 mass% or more and 99 mass% or less, a part of the fibrous fillers is exposed on a surface of the composite resin molding, and at least a part of the surface of the fibrous fillers is coated with hydrolyzable coating resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite resin molded article that has excellent mechanical properties and exhibits sustained drug release properties in a humid environment. [Background technology]

[0002] In agricultural applications, pesticides and fertilizer ingredients are used, while in daily necessities, ingredients are used as insect repellents, insecticides, fragrances, and deodorizing agents. However, these ingredients are sometimes required to be released gradually over a long period of time, i.e., to have sustained release properties.

[0003] Depending on the application, sustained-release agents are required to have such properties as rigidity suitable for use as structural members and biodegradability that allows them to decompose in the natural environment after sustained release.

[0004] Specific examples of sustained-release agents include those in which a drug component is supported on a porous substrate and those in which a drug component is dispersed in a degradable material.

[0005] For example, Patent Document 1 describes a method in which a drug is loaded into porous particles by impregnation with an organic solvent and the surface of the porous particles is coated with a polymer. In this case, the polymer coating the porous particles is destroyed by an external stimulus, releasing the drug.

[0006] Patent Document 2 describes a method in which a drug component is dispersed in a degradable polymer, causing the drug to volatilize as the polymer decomposes. In this method, the release rate of the drug component is controlled by the amount and decomposition rate of the degradable polymer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-12996 [Patent Document 2] Japanese Patent Application Publication No. 4-173746 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in Patent Document 1, the drug is released completely the moment the polymer coating the porous particles is destroyed, making it difficult to maintain continuous efficacy. On the other hand, in Patent Document 2, the rigidity and durability of the sustained-release agent are limited by the properties of the degradable polymer, so the applicable uses are limited.

[0009] The present invention is intended to solve the above-mentioned problems of the prior art, and has an object to provide a composite resin molding that maintains high rigidity during use and has sustained drug release properties. [Means for solving the problem]

[0010] The composite resin molding of the present invention is a composite resin molding containing a main resin and a plurality of fibrous fillers dispersed in the main resin, wherein the fibrous fillers contain a volatile chemical agent, and when the composite resin molding is taken as 100% by mass, the content of the fibrous fillers containing the chemical agent is 10% by mass or more and 99% by mass or less, a portion of the fibrous fillers is exposed on the surface of the composite resin molding, and at least a portion of the surface of the fibrous fillers is coated with a hydrolyzable coating resin. [Effects of the Invention]

[0011] The composite resin molding according to the present invention not only has a higher elastic modulus than a resin alone, but also has sustained drug release properties in a humid environment. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view showing the cross-sectional structure of a composite resin molded body according to a first embodiment. [Figure 2] 2 is a schematic cross-sectional view showing the cross-sectional structure of a fibrous filler that is a constituent member of the composite resin molded product according to the first embodiment. FIG. [Figure 3]1 is a schematic cross-sectional view showing the cross-sectional structure of a composite resin molding containing a fibrous filler having defibrated regions according to embodiment 1. FIG. [Figure 4] 1A to 1C are schematic diagrams illustrating a manufacturing process of a composite resin molded body according to the first embodiment. [Figure 5] 1A and 1B are diagrams showing the configurations and measurement results of composite resin molded bodies in examples and comparative examples according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The composite resin molding of the first aspect is a composite resin molding containing a main resin and a plurality of fibrous fillers dispersed in the main resin, wherein the fibrous fillers contain a volatile drug, and when the composite resin molding is taken as 100% by mass, the content of the fibrous fillers containing the drug is 10% by mass or more and 99% by mass or less, a portion of the fibrous fillers is exposed on the surface of the composite resin molding, and at least a portion of the surface of the fibrous fillers is coated with a hydrolyzable coating resin.

[0014] A composite resin molded product according to a second aspect may be the composite resin molded product according to the first aspect, wherein the moisture content of the fibrous filler is 5% or more as measured by the method specified in ASTM D 1909.

[0015] A composite resin molded product according to a third aspect is the composite resin molded product according to the first or second aspect, wherein the melting point of the coating resin may be in the range of not less than the melting point of the base resin but less than the carbonization temperature of the fibrous filler.

[0016] A composite resin molded article according to a fourth aspect is any one of the first to third aspects, wherein the fibrous filler may be a cellulose.

[0017] A composite resin molding according to a fifth aspect is the composite resin molding according to any one of the first to fourth aspects, wherein the fibrous filler may have defibrated portions at ends in the fiber length direction.

[0018] A method for manufacturing a composite resin molding according to the sixth aspect includes the steps of preparing a drug, a hydrolyzable coating resin, a fibrous filler, and a base resin; impregnating the fibrous filler with the drug; a coating resin melt-kneading step of melt-kneading the fibrous filler together with the coating resin, proceeding with defibration from the end of the fibrous filler in the fiber length direction, thereby increasing the surface area of ​​the defibrated portion at the end and coating at least a portion of the surface of the fibrous filler with the coating resin to form a coated fibrous filler; and a step of kneading the coated fibrous filler together with the base resin to form a composite resin molding in which the coated fibrous filler is dispersed in the base resin.

[0019] A seventh aspect of the method for producing a composite resin molded body is the same as the sixth aspect, and in the step of molding the composite resin molded body, the molding temperature may be set to a temperature that is 125% or less of the melting point of the coating resin.

[0020] Hereinafter, a composite resin molding and a manufacturing method thereof according to an embodiment will be described with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals and the description thereof will be omitted where appropriate.

[0021] (Embodiment 1) Fig. 1 is a schematic cross-sectional view showing the cross-sectional structure of a composite resin molded product 10 according to embodiment 1. Fig. 2 is a schematic cross-sectional view showing the cross-sectional structure of a fibrous filler 2 which is a constituent member of the composite resin molded product 10 according to embodiment 1. The composite resin molding 10 according to the first embodiment is made of a melt-kneaded mixture of a base resin 1 and fibrous filler 2 containing a drug coated with a coating resin 3. As shown in the cross-sectional schematic diagram of FIG. 1, the composite resin molding 10 has fibrous filler 2 containing a drug coated with a coating resin 3 dispersed in the base resin 1.

[0022] In this composite resin molding 10, some of the fibrous fillers 2 are exposed on the surface of the molding, and the fibrous fillers 2 have contact points with each other, so in addition to a high elastic modulus, the molding has high water absorption. In a humid environment, when the coating resin 3 is hydrolyzed due to the absorption of water by the fibrous fillers 2, the drug contained in the fibrous fillers 2 is released, and sustained release is promoted via the contact points between the fibrous fillers 2. Therefore, a composite resin molding 10 can be realized that maintains high rigidity during use and has sustained drug release properties in a humid environment.

[0023] Each of the components constituting this composite resin molded body will be described below.

[0024] <Main resin> In this embodiment, the base resin 1 is preferably a thermoplastic resin in order to ensure good moldability. Examples of thermoplastic resins include olefin resins (including cyclic olefin resins), styrene resins, (meth)acrylic resins, organic acid vinyl ester resins or derivatives thereof, vinyl ether resins, halogen-containing resins, polycarbonate resins, polyester resins, polyamide resins, thermoplastic polyurethane resins, polysulfone resins (such as polyethersulfone and polysulfone), polyphenylene ether resins (such as 2,6-xylenol polymers), cellulose derivatives (such as cellulose esters, cellulose carbamates, and cellulose ethers), silicone resins (such as polydimethylsiloxane and polymethylphenylsiloxane), rubber or elastomers (such as diene rubbers like polybutadiene and polyisoprene, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylic rubbers, urethane rubbers, and silicone rubbers), and biomass plastics (such as polylactic acid, polybutylene succinate, polyhydroxyalkanoic acid, and other biodegradable resins). These resins may be used alone or in combination. The base resin 1 is not limited to the above materials as long as it has thermoplastic properties.

[0025] Among these thermoplastic resins, the main resin 1 is preferably an olefin-based resin having a relatively low melting point. Examples of olefin-based resins include homopolymers of olefin-based monomers, copolymers of olefin-based monomers, and copolymers of olefin-based monomers with other copolymerizable monomers. Examples of olefin-based monomers include linear olefins (α-C2-20 olefins such as ethylene, propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, and 1-octene), and cyclic olefins. These olefin-based monomers may be used alone or in combination. Of the above olefin-based monomers, linear olefins such as ethylene and propylene are preferred. Other copolymerizable monomers include, for example, fatty acid vinyl esters such as vinyl acetate and vinyl propionate; (meth)acrylic monomers such as (meth)acrylic acid, alkyl (meth)acrylates, and glycidyl (meth)acrylate; unsaturated dicarboxylic acids or anhydrides such as maleic acid, fumaric acid, and maleic anhydride; vinyl esters of carboxylic acids (e.g., vinyl acetate and vinyl propionate); cyclic olefins such as norbornene and cyclopentadiene; and dienes such as butadiene and isoprene. These copolymerizable monomers may be used alone or in combination. Specific examples of olefin-based resins include copolymers of linear olefins (e.g., α-C2-4 olefins), such as polyethylene (e.g., low-density, medium-density, high-density, or linear low-density polyethylene), polypropylene, ethylene-propylene copolymers, and terpolymers such as ethylene-propylene-butene-1.

[0026] <Fiber filler> Next, the fibrous filler 2 will be described. The fibrous filler 2 (hereinafter, sometimes simply referred to as fiber) contained in the composite resin molded product 10 in this embodiment absorbs water in a humid environment. Therefore, the fibrous filler added to the composite resin molded product is used primarily for the first purpose of bringing the coating resin 3 into contact with water and hydrolyzing it. For this purpose, the fibrous filler 2 preferably has high water absorption, and the moisture content of the fibrous filler 2 is preferably 5% or more as determined by the method specified in ASTM D 1909. Specifically, rayon, vinylon, aramid, pulp, cellulose, cellulose nanofiber, lignocellulose, lignocellulose nanofiber, cotton, silk, hemp, chitosan fiber, wool, etc. are preferred.

[0027] The second purpose of adding the fibrous filler 2 is to improve mechanical properties and dimensional stability by reducing the linear expansion coefficient. For this purpose, the fibrous filler 2 preferably has a higher modulus of elasticity than the base resin 1. Specific examples include pulp, cellulose, cellulose nanofiber, lignocellulose, lignocellulose nanofiber, cotton, silk, hemp, chitosan fiber, and wool. Among these, celluloses are particularly preferred from the viewpoints of availability, high modulus of elasticity, and low linear expansion coefficient. However, the fibrous filler 2 is not limited to the above materials as long as it can improve mechanical properties and has water absorption.

[0028] The content of drug-containing fibrous filler 2 in composite resin molding 10 is preferably 10% by mass or more and 99% by mass or less, when composite resin molding 10 is taken as 100% by mass. If the content of drug-containing fibrous filler 2 is less than 10% by mass, the fibrous fillers 2 are unlikely to come into contact with each other inside composite resin molding 10, resulting in insufficient water absorption. On the other hand, if the content of drug-containing fibrous filler 2 is more than 99% by mass, the proportions of base resin 1 and coating resin 3 become smaller, which eliminates the effect of bonding the fibrous fillers 2 together and reduces moldability.

[0029] The form of the fibrous filler 2 in the composite resin molded product 10 will be described. The larger the bonding interface between the fibrous filler 2 and the coating resin 3, the more accelerated the hydrolysis of the coating resin 3 when the fibrous filler 2 absorbs water, so it is preferable that the specific surface area of ​​the fibrous filler 2 is high. On the other hand, to improve the water absorption of the composite resin molded product 10, it is preferable that the fibrous filler 2 is exposed on the surface of the composite resin molded product 10. When the fibrous filler 2 is exposed on the surface of the composite resin molded product 10, water is absorbed from the exposed portion and absorbed into the interior of the composite resin molded product 10 due to the capillary action of the fibers. The smaller the specific surface area of ​​the fibrous filler 2 exposed on the surface of the molded product, the higher the water absorption. This is because when the specific surface area of ​​the fibrous filler 2 exposed on the surface is large, the water repellency is enhanced due to the effect of fine unevenness. Furthermore, as shown in Figure 3, by having a defibrated area 4 at the end of the fibrous filler 2, the specific surface area of ​​the defibrated area 4 increases, and the number of contact points between the fibrous fillers 2 increases, making it possible to increase the water absorption rate through the contact points of the fibrous filler 2 in a humid environment.

[0030] The central portion of the undefibrated fibrous filler 2, which has a small specific surface area, is less entangled with the main resin 1 and is more likely to be exposed on the surface of the molded body depending on the molding conditions. Conversely, the tip portion of the defibrated fibrous filler 2 is more entangled with the main resin 1 and penetrates into the interior together with the main resin 1. This makes it possible to obtain a composite resin molded body 10 in which the central portion of the fibrous filler 2, excluding both end portions, is exposed on the surface.

[0031] The tip defibrated region 4 is preferably 5% or more and 50% or less of the entire fiber length L of the fibrous filler 2. If the defibrated region 4 is less than 5% of the entire fiber length L, the specific surface area is small and no improvement in the elastic modulus is observed, and if it is longer than 50%, the defibrated region 4 with a large aspect ratio is exposed on the surface of the molded body, resulting in a deterioration in water absorbency.

[0032] Next, the characteristics of the fibrous filler 2 will be described. The types of base resin 1 and fibrous filler 2 are as described above. However, if the fibrous filler 2 is too soft relative to the base resin 1, i.e., has a low elastic modulus, the composite resin molding 10 will have a low overall elastic modulus, resulting in reduced strength. On the other hand, if the fibrous filler 2 is too hard relative to the base resin 1, i.e., has a high elastic modulus, shock waves generated upon impact will not propagate but will be absorbed at the interface between the base resin 1 and the fibrous filler 2. This will result in cracks and crazes occurring near the interface, resulting in reduced impact strength. Therefore, in the relationship between the elastic moduli of the base resin 1 and the fibrous filler 2, it is preferable that the elastic modulus of the fibrous filler 2 be higher, and that the difference between them be as small as possible. The optimal relationship is calculated from simulation results, and it is preferable that the difference in elastic modulus between the base resin 1 and the fibrous filler 2 be within 20 GPa.

[0033] In addition, these fibrous fillers 2 may be surface-treated for the purpose of improving adhesion to the base resin 1 or the coating resin 3 or dispersibility in the composite resin molding 10, but if the surface treatment impairs the water absorption properties of the fibrous fillers 2, it is preferable not to perform the surface treatment in advance.

[0034] <Additives> Additives may be used as needed to improve the affinity between the base resin 1, the coating resin 3 and the fibrous filler 2, for example.

[0035] <Coating resin> Next, the coating resin 3 will be described. The coating resin 3 in this embodiment is used to protect the drug contained in the fibrous filler 2 and prevent the drug from being released from the composite resin molded product 10 during use. In a humid environment, the coating resin 3 must decompose to release the drug contained in the fibrous filler 2 in order to achieve sustained drug release. For this reason, the coating resin 3 is preferably a hydrolyzable resin that decomposes in an environment with a humidity of 50% or more. Specific examples include polyester resins such as polylactic acid, polybutylene terephthalate, and polycarbonate. Furthermore, to ensure good moldability, a thermoplastic resin is preferred, and the above resins may be used alone or in combination. The coating resin 3 is not limited to the above materials as long as they have hydrolysis properties.

[0036] Furthermore, in order for the coating resin 3 to maintain a state in which it coats at least a portion of the surface of the fibrous filler 2 in the composite resin molding 10, it is preferable that the melting point of the coating resin 3 be equal to or higher than the melting point of the main resin 1 and lower than the carbonization temperature of the fibrous filler 2. If the melting point of the coating resin 3 is equal to or higher than the melting point of the main resin 1, it will not melt during molding of the composite resin molding 10, and if the melting point is lower than the carbonization temperature of the fibrous filler 2, it can coat the fibrous filler 2 without degrading it.

[0037] The state of the coating resin 3 in the composite resin molding 10 will be described. By controlling the amount of the coating resin 3 coated on the fibrous filler 2, it is possible to delay the release of the drug contained in the fibrous filler 2 and control the sustained release rate.

[0038] <Drugs> Next, the chemical agent will be described. The chemical agent in this embodiment is used as a sustained-release component of the composite resin molding 10 in a humid environment. The chemical agent in this embodiment can be an insect repellent, insecticide, fragrance, deodorizer, pesticide, fertilizer component, or the like, depending on the purpose, and liquid or solid chemical agents can also be used depending on other purposes. In other words, the type of chemical agent is not particularly limited as long as it can be contained in the fibrous filler 2.Specifically, insect repellents and bio-repellents include hinokitiol, safrole, limonene, linalool, menthol, 1,8-cineole, citral, eugenol, capsaicin, camphor, vanillin, α-pinene, β-pinene, anethole, anisaldehyde, acetophenone, cinnamyl alcohol, leaf alcohol, geraniol, naphthalene, diethyltoluamide, lemongrass oil, synthetic musk, pine oil, and terpineol. , wood vinegar, hexanol, geranyl formate, gamma-lactone, angelica, cyclic terpene alcohol, N,N-diethyl-m-toluamide, ethyl ometone, isothionate, cresol, nonyl laritan, linalool, 2-butoxyethanol, bis ether, isophorone, spearmint oil, cinnamon alcohol, methyl nonyl ketone, eucalyptol, allyl isocyanate, cycloheximide, spearmint oil, orange oil, lemon oil, mandarin oil, lime Oil, camphor oil, cassia oil, linaloe oil, peppermint oil, clove oil, pimento oil, bay oil, star anise oil, fennel oil, jasmine oil, pepper, peppermint, perilla, clove, vanilla, thyme, tansy, rosemary, rosehip, bronze fennel, horseradish, borage, meadowsweet, black mallow, rose geranium, rhubarb, Italian parsley, bergamot, wild strawberry, rocket salad, ginger mint, Examples include extracts extracted from herbs and spices such as peppermint, cottage pink, moss cured parsley, salad burnet, marjoram, olive, curd, pineapple sage, lemon thyme, lemon balm, garden sage, Roman chamomile, English lavender, lemon bergamot, heartsea, hyssop, pennyroyal, cleansing thyme, garden sage, spearmint, bay, Greek oregano, and ribwort.Examples of aromatic or deodorizing agents include natural fragrances such as lemon oil, lime oil, spearmint oil, jasmine oil, orange oil, pine oil, peppermint oil, lavender oil, and musk oil, as well as synthetic fragrances made from these fragrances, such as limonene, linamol, eugenol, citranellol, vanillin, carvone, rose oxide, indole, geranyl acetate, and ethyl benzoate.

[0039] The above-mentioned chemicals may be used alone or in combination of two or more kinds. However, the chemicals are not limited to the above-mentioned materials, as long as they are volatile chemicals that can be used for insect repellent, insecticide, fragrance, deodorizer, pesticide, fertilizer component, or other purposes.

[0040] <Method of manufacturing composite resin molded body> Next, a description will be given of a method for manufacturing the composite resin molded body 10. Fig. 4 is a flow diagram illustrating an example of a manufacturing process for the composite resin molded body 10 according to this embodiment. (1) A drug is loaded in advance onto the fibrous filler 2. The ratio of the drug to be contained varies depending on the combination of the drug and the fibrous filler, and methods for loading the drug include physical adsorption by dry blending and impregnation using a dispersion solvent. The loading method is not limited to the above, as long as it can retain the drug on the fibrous filler 2.

[0041] (2) Fibrous filler 2 and coating resin 3 are placed in a melt-kneading treatment device and melt-kneaded within the device. This melts the coating resin 3, and the fibrous filler 2 is dispersed in the molten coating resin 3. At the same time, the shearing action of the device promotes defibration of agglomerates of fibrous filler 2, allowing the fibrous filler 2 to be finely dispersed in the coating resin 3. By adjusting the shearing conditions at this time, it is also possible to defibrate the ends of the fibrous filler 2, obtaining defibrated regions 4, as shown in Figure 3.

[0042] Conventionally, when fibers are composited into resins, fibers that have been defibrated in advance through pretreatment such as wet dispersion have been used. However, when fibrous fillers are defibrated in the solvent used in wet dispersion, the fibers swell due to the solvent. Therefore, in order for the fibrous filler to absorb water and expand sufficiently in the composite resin molding, it is necessary to dry the solvent in the fibrous filler before mixing it with the base resin. Furthermore, because defibration by wet dispersion is easier than defibration in a molten base resin, it is difficult to defibrate only the ends, and the entire fibrous filler ends up in a defibrated state. Furthermore, adding pretreatment increases the number of processes, resulting in reduced productivity.

[0043] In contrast, in the manufacturing process for the composite resin molding 10 in this embodiment, the fibrous filler 2 is melt-kneaded together with the coating resin 3 (all-dry method) without undergoing pretreatment by wet dispersion for the purpose of defibrating the fibrous filler. In this method, by not performing wet dispersion treatment of the fibrous filler 2, swelling of the fibrous filler 2 during the manufacturing process can be suppressed, and the water absorption rate of the fibrous filler 2 in the composite resin molding 10 can be improved. By drying the fibrous filler 2 beforehand or during kneading, the water absorption rate in the composite resin molding 10 in a humid environment can be further improved. Furthermore, since the fibrous filler 2 has the defibrated regions 4 as described above, there are many contact points between the fibers within the composite resin molding 10, and the water absorption rate of the composite resin molding 10 can be increased via the contact points between the fibers.

[0044] To produce the fibrous filler 2 of this embodiment using an all-dry method, it is preferable to apply high shear stress during kneading. Specific kneading techniques include kneading methods using a single-screw kneader, twin-screw kneader, roll kneader, Banbury mixer, or a combination thereof. From the viewpoint of being able to easily apply high shear and being highly suitable for mass production, continuous twin-screw kneaders and continuous roll kneaders are particularly preferred. Other kneading techniques may also be used as long as they can apply high shear stress.

[0045] (3) The composite resin composition of the fibrous filler 2 and the coating resin 3 extruded from the melt kneading apparatus can be pulverized by a cutter or a pulverizer to obtain the fibrous filler 2 at least partially coated on its surface with the coating resin 3 of the present embodiment. Specific methods include pulverization methods using a pulverizer such as a pelletizer, a ball mill, a roll mill, a hammer mill, a wonder crusher, a jet pulverizer, or a combination thereof. Any pulverization method other than those described above may be used as long as it can maintain the state in which at least a portion of the fibrous filler 2 is coated with the coating resin 3.

[0046] (4) By dry-blending the base resin 1 and the fibrous filler 2 coated with the coating resin 3 and then injection-molding the mixture, an injection-molded product can be produced as a composite resin molding 10. The molding temperature during injection molding is preferably 125% or less of the melting point of the coating resin 3. If the molding temperature is higher than 125% of the melting point of the coating resin 3, the coating resin 3 will melt and disperse into the base resin 1 during molding.

[0047] Hereinafter, examples and comparative examples of the experiments conducted by the inventors will be described.

[0048] Example 1 In Example 1, a cellulose-composite polypropylene resin molded article was produced by the following production method.

[0049] Softwood pulp (manufactured by Mitsubishi Paper Mills, product name: NBKP Celgar) was used as the starting material for the fibrous filler. Limonene (manufactured by Tokyo Chemical Industry Co., Ltd., L0047), a citrus fragrance component, was used as the volatile chemical. The softwood pulp was immersed in limonene and pulverized using a roll mill. The excess limonene was then removed to obtain a limonene-containing cellulose filler with a mass ratio of cellulose filler to limonene of 90:10.

[0050] Polylactic acid (manufactured by Unitika, product name: TE-2000) as a coating resin and the above-mentioned limonene-containing cellulose filler were weighed out in a mass ratio of 50:50 and dry-blended. Then, the mixture was melt-kneaded in a twin-screw kneader (KRC Kneader, manufactured by Kurimoto Iron Works). The screw was a medium shear type. The melt-kneading conditions were a material temperature of 200°C and a rotation speed of 50 min. -1 The composite resin composition discharged from the twin-screw kneader was hot-cut to prepare cellulose-composite polylactic acid resin pellets.

[0051] The cellulose-composite polylactic acid pellets were crushed in a Wonder Crusher (WC-3, manufactured by Osaka Chemical Co., Ltd.) at a rotation speed of 15,000 rpm to obtain cellulose fibers coated with polylactic acid resin.

[0052] The cellulose fibers coated with polylactic acid resin and polypropylene resin (manufactured by Prime Polymer, product name: J108M) as the main resin were weighed in a mass ratio of 50:50 and dry blended. Then, they were melt-kneaded in a twin-screw kneader (KRC Kneader, manufactured by Kurimoto Iron Works). The screw was a medium shear type. The melt-kneading conditions were a material temperature of 180°C and a rotation speed of 50 min. -1 The composite resin composition discharged from the twin-screw kneader was hot-cut to produce cellulose-composite polypropylene resin pellets with a mass ratio of base resin, drug-containing fibrous filler, and coating resin of 50:25:25.

[0053] Then, test specimens of cellulose-composite polypropylene resin molded bodies were prepared using an injection molding machine (180AD manufactured by Japan Steel Works, Ltd.). The test specimen preparation conditions were: base resin temperature 200°C, mold temperature 50°C, injection speed 100 mm / s, and holding pressure 100 Pa. Dumbbell-shaped test specimens of JIS K7139 Type A12 size were prepared.

[0054] (Evaluation of fiber water absorption) The water absorbency of the fibers was evaluated by measuring the moisture content of the fibers according to the method specified in ASTM D 1909. Specifically, the weight of the fibers dried at 80°C for 24 hours was measured and used as the reference weight. The weight of the fibers was then measured after being kept at a temperature of 20°C and a humidity of 65% for 24 hours. The moisture content was calculated by taking the increase in weight from the reference weight as the moisture content. A moisture content of less than 5% was rated as x, and a moisture content of 5% or more was rated as o. The moisture content of the softwood pulp was 6.5%, and was rated as o.

[0055] (Fiber end defibration) The obtained cellulose composite polypropylene resin molded body was immersed in chloroform solvent to dissolve the polypropylene and polylactic acid, and the shape of the remaining cellulose fibers was observed using a scanning electron microscope. The ends of the fibers were found to be in a defibrated state.

[0056] (Evaluation of elastic modulus of composite resin molding) A three-point bending test was carried out using the obtained test piece. Here, the elastic modulus was evaluated as follows: if the value was less than 200 MPa, it was marked as x; if it was 200 MPa or more, it was marked as o. The elastic modulus of the test piece was 326 MPa, and it was marked as o.

[0057] (Evaluation of sustained release properties of composite resin molded body) A sustained release test was conducted using the obtained test piece. The temperature was maintained at 60°C and humidity at 50% using a hot air dryer, and the release duration until the fragrance disappeared from the test piece was measured under that environment. The presence or absence of fragrance was measured by measuring the air near the surface of the test piece using an odor measuring device (OMU-Sn manufactured by Futaba Electronics) equipped with a light odor sensor, and the release duration was defined as the time from the start of measurement until the odor intensity fell below 1000. To evaluate sustained release, a release duration of 500 hours or more was marked as ○, and one less than 500 hours was marked as ×. The release duration of this test piece was 720 hours or more, and it was rated as ○.

[0058] Example 2 In Example 2, the mass ratio of the base resin, drug-containing fibrous filler, and coating resin was changed to 67.5:25:7.5, and the other material conditions and process conditions were the same as in Example 1 to produce a cellulose-composite polypropylene resin molded product. Evaluations similar to those in Example 1 were also carried out.

[0059] (Comparative Example 1) In Comparative Example 1, an uncoated drug-containing cellulose filler was used. The mass ratio of the base resin to the drug-containing cellulose filler was changed to 25:75, and the other material and process conditions were the same as in Example 1 to produce a cellulose-composite polypropylene resin molded product. The evaluation was also performed in the same manner as in Example 1.

[0060] (Comparative Example 2) In Comparative Example 2, a drug-containing PET fiber was produced using PET fibers with a fiber diameter of 20 μm and a fiber length of 100 μm instead of softwood pulp. The other material conditions and process conditions were the same as in Example 1, and a polypropylene composite resin molding was produced. The evaluation was also performed in the same manner as in Example 1.

[0061] (Comparative Example 3) In Comparative Example 3, the coating resin and the drug were melt-kneaded at a mass ratio of 95:5 without using a fibrous filler. The mass ratio of the base resin to the drug-containing polylactic acid resin was changed to 50:50, and the other material and process conditions were the same as in Example 1 to produce a polypropylene composite resin molded body. The same evaluation as in Example 1 was also carried out.

[0062] The structures and measurement results of the composite resin molded bodies in Examples 1 and 2 and Comparative Examples 1 to 3 are shown in FIG.

[0063] As is clear from Figure 5, in Examples 1 and 2, in which the drug contained in the fibrous filler was protected by a coating resin, the modulus of elasticity was high at 200 MPa or more, and in the sustained release test in a humid environment, sustained release was confirmed compared to Comparative Example 3. Furthermore, compared to Example 2, Example 1, which had a higher proportion of coating resin, showed sustained release for a longer period of time.

[0064] It was confirmed that when a fibrous filler containing a volatile drug is composited, at least a portion of the fiber surface of the fibrous filler is coated with a hydrolyzable resin, the fiber is exposed on the surface of the composite resin molding, and the water absorption rate of the fibrous filler is high, a composite resin with a high elastic modulus and sustained drug release properties can be obtained.

[0065] Comparative Example 1, which was produced without using a coating resin, had an improved elastic modulus due to the addition of a fibrous filler compared to Comparative Example 3. However, because the drug was not protected by a coating resin, the sustained release duration was shorter than in Example 1, and the product was evaluated as x.

[0066] In Comparative Example 2, which was produced using PET fiber as the fibrous filler, the moisture content of the PET fiber was low and it was not water-absorbent, so in the sustained release evaluation, hydrolysis of the polylactic acid resin did not progress, and the release duration was shorter than in Example 1, resulting in an evaluation of x.

[0067] Comparative Example 3, which was produced without using a fibrous filler, did not exhibit sustained release properties, and the sustained release property evaluation was poor.

[0068] From the above evaluations, it was confirmed that if a volatile drug is contained in an absorbent fibrous filler, at least a portion of the fiber surface is coated with a hydrolyzable coating resin, and the fiber is exposed on the surface of the composite resin molding, a composite resin molding with a high elastic modulus and sustained drug release properties can be obtained.

[0069] In addition, the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and can achieve the effects of each embodiment and / or example. [Industrial Applicability]

[0070] According to the composite resin molding of the present invention, it is possible to provide a fiber composite resin molding that has the ability to sustain the release of insect repellent or insecticidal ingredients, fragrance or deodorizing ingredients, pesticide or fertilizer ingredients, and other medicinal ingredients, and that has high rigidity that makes it applicable to structural components, thereby having the ability to sustain the release of medicinal ingredients. [Explanation of symbols]

[0071] 1. Base resin 2. Fibrous filler 3. Coating resin 4 Defibration site 10 Composite resin molding

Claims

1. A base resin, a plurality of fibrous fillers dispersed in the base resin; A composite resin molding comprising: The fibrous filler contains a volatile agent, When the composite resin molding is taken as 100% by mass, the content of the fibrous filler containing the drug is 10% by mass or more and 99% by mass or less, a portion of the fibrous filler is exposed on the surface of the composite resin molding, At least a portion of the surface of the fibrous filler is coated with a hydrolyzable coating resin, The composite resin molded product, wherein the fibrous filler is a cellulose.

2. 2. The composite resin molding according to claim 1, wherein the moisture content of the fibrous filler is 5% or more as measured by the method specified in ASTM D 1909.

3. 3. The composite resin molding according to claim 1, wherein the melting point of the coating resin is equal to or higher than the melting point of the base resin and is lower than the carbonization temperature of the fibrous filler.

4. The composite resin molding according to claim 1 , wherein the fibrous filler has defibrated portions formed at ends in the fiber length direction.

5. A step of preparing a volatile agent, a fibrous filler, a hydrolyzable coating resin, and a base resin; impregnating the agent into the fibrous filler; a coating resin melt-kneading step in which the fibrous filler is melt-kneaded together with the coating resin, and defibration proceeds from the end of the fibrous filler in the fiber length direction, thereby expanding the surface area of ​​the defibrated portion at the end and coating at least a part of the surface of the fibrous filler with the coating resin to form a coated fibrous filler; kneading the coated fibrous filler together with the base resin to form a composite resin molding in which the coated fibrous filler is dispersed in the base resin; Including, The method for producing a composite resin molded body, wherein the fibrous filler is a cellulose.

6. The method for producing a composite resin molded body according to claim 5 , wherein in the step of molding the composite resin molded body, the molding temperature is set to a temperature that is 125% or less of the melting point of the coating resin.

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