Composite resin molded body containing plant fibers with sustained fragrance release properties

Abstract

To provide a composite resin molding having aroma sustained release properties for a long period of time without depending on a surrounding environmental condition.SOLUTION: A vegetable fiber-containing composite resin molding having aroma sustained release properties includes a main agent resin, vegetable fibers, and dispersant. The vegetable fibers contain aroma components. The main agent resin comprises a crystalline resin. The content of the vegetable fibers is 50-90 mass% when the total amount of the main agent resin, the vegetable fibers and the dispersant is 100 mass%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a plant fiber-containing composite resin molded body having aroma slow-release properties.

Background Art

[0002] So-called "general-purpose plastics" such as polyethylene (PE) and polypropylene (PP) are relatively inexpensive, have a weight that is a fraction of that of metals or ceramics, and are easy to process such as molding. Therefore, general-purpose plastics are used as materials for various daily necessities such as bags, various packages, various containers, sheets, etc., and also for industrial parts such as automotive parts and electrical parts, as well as daily necessities and miscellaneous goods.

[0003] In recent years, for products close to daily life such as daily necessities and household products using resin, and for appearance parts such as home appliance housings and interior and exterior parts of automobiles, functional characteristics are required as added values other than basic performance. Examples of functional characteristics include texture and touch such as feel, color, and fragrance. In particular, fragrance is suitable for imparting to products close to daily life because it has effects such as improving mood and relaxation effects. Examples of methods for imparting fragrance include methods of supporting or containing an aromatic component in a resin.

[0004] On the other hand, even if the fragrance is a good fragrance, a large amount of it will make people feel uncomfortable. Therefore, it is necessary to release an appropriate amount of fragrance. Also, since fragrance is due to volatile aromatic components, it is difficult to sustain the effect of fragrance for a long time, that is, to impart aroma slow-release properties. Therefore, simply supporting or containing an aromatic component in a resin cannot control the release amount and release rate of the aromatic component, and conversely, it may make people feel uncomfortable or the fragrance cannot be sustained for a long time. In Patent Document 1, an appropriate amount of aromatic component is slowly released over a long period by supporting the aromatic component in a composite resin containing cellulose-based particles.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-201811 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the composite resin described in Patent Document 1, the release rate of the fragrance component is controlled solely by the rate of repeated moisture absorption and drying (breathing rate) of the cellulose particles in the composite resin, so the release rate changes significantly depending on the surrounding environmental conditions. Therefore, there is a problem that it can only stably maintain fragrance release over a long period of time under specific environmental conditions. In addition, there is a problem that a separate process is required to support the fragrance component on the composite resin.

[0007] The present invention aims to solve the aforementioned conventional problems and to provide a composite resin molded article that has sustained fragrance release properties over a long period of time, regardless of the surrounding environmental conditions. [Means for solving the problem]

[0008] The composite resin molded article according to the present invention comprises a main resin, plant fibers, and a dispersant. The aforementioned plant fiber contains aromatic components, The main resin is a crystalline resin, When the total amount of the main resin, the plant fibers, and the dispersant is taken as 100% by mass, the content of the plant fibers is 50% by mass or more and 90% by mass or less. [Effects of the Invention]

[0009] The composite resin molded article according to the present invention uses plant fibers containing aromatic components and a crystalline resin as the main resin, and contains plant fibers at a high concentration of 50% to 90% by mass. As a result, the degree of crystallinity around the plant fibers and the entire resin is high, and the release rate of aromatic components volatilized from the plant fibers is suppressed. Therefore, this composite resin molded article has long-term sustained fragrance release properties. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the structure of a plant fiber-containing composite resin molded body according to Embodiment 1. [Figure 2] This is a schematic diagram showing the orientation and crystalline state of plant fibers in the skin layer and core layer of a composite resin molded body according to Embodiment 1. [Figure 3A] This figure shows the conditions in Examples 1-8 and Comparative Examples 1-4. [Figure 3B] This figure shows the measurement results for Examples 1-8 and Comparative Examples 1-4. [Modes for carrying out the invention]

[0011] The composite resin molded article according to the first embodiment comprises a main resin, plant fibers, and a dispersant. The aforementioned plant fiber contains aromatic components, The main resin is a crystalline resin, When the total amount of the main resin, the plant fibers, and the dispersant is taken as 100% by mass, the content of the plant fibers is 50% by mass or more and 90% by mass or less.

[0012] The composite resin molded article according to the second embodiment is the composite resin molded article according to claim 1, wherein the average particle size of the plant fibers is 1 μm or more and 3 mm or less, in the first embodiment described above.

[0013] In the third embodiment, the composite resin molded article may have a crystallinity of 30% or more of the main resin, as in the first or second embodiment described above.

[0014] In the fourth embodiment, the composite resin molded article may have a crystallinity of 1.05 times or more of the crystallinity of the main resin around the plant fibers in the composite resin molded article compared to the portion consisting only of the main resin, in any of the first to third embodiments described above.

[0015] In the composite resin molded body according to the fifth aspect, in any of the first to fourth aspects, in the particle size distribution of the plant fiber, the particle size d90 at which the ratio of particles below that numerical value is 90%, and the particle size d10 at which the ratio of particles below that numerical value is 10% are used, and the variation Δd in particle size represented by Δd = d90 / d10 may be 6 or more.

[0016] In the composite resin molded body according to the sixth aspect, in any of the first to fifth aspects, the fiber length direction of the plant fiber in the skin layer of the composite resin molded body may be oriented at an angle of 0° or more and 30° or less with respect to the surface of the composite resin molded body.

[0017] In the composite resin molded body according to the seventh aspect, in any of the first to sixth aspects, the thickness of the skin layer on the surface of the composite resin molded body may be 600 μm or less.

[0018] Hereinafter, the plant fiber-containing composite resin molded body according to the embodiment will be described with reference to the drawings. In the following description, the same reference numerals are given to the same components, and the description thereof is omitted as appropriate.

[0019] (Embodiment 1) FIG. 1 is a schematic view showing the configuration of a plant fiber-containing composite resin molded body 10 according to Embodiment 1. FIG. 2 is a schematic view showing the orientation and crystal state of the plant fiber in the skin layer and the core layer of the composite resin molded body 10 according to Embodiment 1. The composite resin molded body 10 according to Embodiment 1 is composed of a main resin 1 composed of a matrix of an amorphous portion 11 and a crystalline portion 12, a plant fiber 2, an aromatic component 3, and a dispersant 4. As shown in FIG. 1, in the composite resin molded body 10, the plant fiber 2, the aromatic component 3, and the dispersant 4 are dispersed in the matrix of the main resin 1. The aromatic component 3 exists inside the plant fiber 2 and in the matrix of the main resin 1, and the dispersant 4 exists at the interface between the plant fiber 2 and the main resin 1. Further, as shown in FIG. 2, the composite resin molded body is roughly composed of two layers: a surface skin layer 13 and an inner core layer 14. When the molten resin enters the mold during molding, the surface of the resin in contact with the mold surface is rapidly cooled, and the rest of the resin inside is slowly cooled. Since the cooling rate is different between the surface and the inside, characteristics such as the degree of crystallinity are different, and it is possible to distinguish the skin layer and the core layer by microscopic observation or the like. In this specification, the layer on the surface of the molded body that is rapidly cooled during molding is defined as the skin layer, and the layer inside the molded body that is slowly cooled during molding is defined as the core layer. According to this composite resin molded body 10, for example, a plant fiber 2 containing an aromatic component and a crystalline main resin 1 are used, and the plant fiber 2 is contained at a high concentration of 50% by mass or more and 90% by mass or less. Therefore, the degree of crystallinity around the plant fiber 2 and the degree of crystallinity of the entire resin are high, and the release rate of the aromatic component 3 volatilized from the plant fiber 2 is suppressed. Therefore, this composite resin molded body 10 has long-term aromatic sustained release properties.

[0020] Hereinafter, the members constituting the composite resin molded body  10 will be described.

[0021] <Main resin> In the embodiment, the main resin 1 is preferably a crystalline resin in order to suppress the release of volatile components, and more preferably a thermoplastic resin in order to ensure good moldability. Examples of crystalline resins include olefin resins (including cyclic olefin resins), polyamide resins, polyphenylene ether resins (such as polymers of 2,6-xylenol), crystalline polyester resins, halogen-containing resins, and liquid crystal polymer resins. The above resins may be used alone or in combination of two or more types. The main resin is not limited to the above materials as long as it is crystalline. Furthermore, when using two or more types of resins, it is sufficient that at least one of the resins is crystalline.

[0022] Of these crystalline resins, the main resin is preferably an olefin-based resin with a relatively low melting point. 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 (such as ethylene, propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, and 1-octene, which are α-C2-20 olefins), and cyclic olefins. These olefin-based monomers may be used individually or in combination of two or more. Among the above olefin-based monomers, linear olefins such as ethylene and propylene are preferred. Specific examples of olefin resins include polyethylene (low-density, medium-density, high-density, or linear low-density polyethylene, etc.), polypropylene, ethylene-propylene copolymers, terpolymers such as ethylene-propylene-butene-1, and copolymers of linear olefins (especially α-C2-4 olefins).

[0023] The main resin 1 is preferably a crystalline resin. The crystalline portion has a denser structure than the amorphous portion. Therefore, the diffusion rate of liquids and gases is significantly lower in the crystalline portion compared to the amorphous portion. Since the aromatic components diffuse as gaseous or liquid components in the composite resin molded body, the diffusion rate is greatly reduced in the crystalline portion compared to the amorphous portion. The presence of crystalline portions in the resin reduces the diffusion rate of aromatic components, thereby maintaining the release of aromatic components from the composite resin molded body for a long period of time, that is, allowing for the gradual release of aromatic components. For this reason, the main resin 1 is preferably a crystalline resin.

[0024] <Plant Fiber> Examples of natural materials that can be used as raw materials for plant fiber 2 in the embodiment include pulp, wood (coniferous trees, hardwoods), cotton linters, kenaf, Manila hemp (abaca), sisal hemp, jute, sabaigrass, esparto grass, bagasse, rice straw, wheat straw, wheat, reeds, bamboo, and tea leaves. Plant waste materials discarded after commercial use, such as sake barrels, may also be used. Alternatively, natural materials modified with functional monomers containing acids, amines, epoxy, etc. may be used. Plant fiber 2 is preferably in the form of fibers or particles obtained by crushing the above-mentioned natural materials.

[0025] <Aromatic ingredients> In the embodiment, the aromatic component 3 is preferably a component derived from natural materials or a component generated when a component derived from natural materials is altered during the manufacturing process of the material, and is more preferably volatile. Examples of aromatic components include pinene, cadinol, and hinokiol. However, the aromatic component is not limited to the above components as long as it is a component contained in plant fibers.

[0026] <Dispersant> Examples of the dispersant 4 in the embodiment include various titanate coupling agents, silane coupling agents, unsaturated carboxylic acids, maleic acid, maleic anhydride, or modified polyolefins grafted with the anhydride, fatty acids, fatty acid metal salts, and fatty acid esters. The silane coupling agent is preferably unsaturated hydrocarbon or epoxy-based. The surface of the dispersant may be modified by treatment with a thermosetting or thermoplastic polymer component. The dispersant 4 is appropriately selected based on the combination of the main resin 1 and the plant fiber 2.

[0027] The plant fiber 2 is preferably a plant fiber containing aromatic components, and it is preferable that the aromatic components are derived from the plant fiber. If a plant fiber that does not contain aromatic components is used, a separate process for supporting the aromatic components will be required. For example, when supporting aromatic components in a composite resin composition, a post-process such as immersing the composite resin composition in an oil containing aromatic components will be required. Furthermore, since the composite resin molded body containing plant fibers will have the texture of plant fibers in its appearance, if the aromatic components are components other than those derived from the plant fiber, an incongruity in appearance and scent may occur, potentially reducing the overall sensory appeal of the composite resin molded body. For this reason, the plant fiber is preferably a plant fiber containing aromatic components, and it is preferable that the aromatic components are derived from the plant fiber.

[0028] The main resin 1, plant fibers 2, and dispersant 4 in the composite resin molded product are in amounts totaling 100% by mass. Since the aromatic component 3 is contained in plant fibers 2, it is included in the amount of plant fibers 2.

[0029] The plant fiber content in the composite resin molded article is preferably 50% by mass or more and 90% by mass or less, and more preferably 55% by mass or more and 75% by mass or less, from the viewpoint of the content of aromatic components and the degree of crystallinity of the main resin.

[0030] As shown in Figure 1, the composite resin molded body is composed of a main resin 1, plant fibers 2, fragrance components 3, and a dispersant 4. The main resin 1 functions as a matrix, with the plant fibers 2, fragrance components 3, and dispersant 4 dispersed within it. In the composite resin molded body, the plant fibers 2 not only act as a source for the release of fragrance components 3 but also function as a crystal nucleating agent, thereby improving the crystallinity of the main resin. Because the plant fibers 2 function as a crystal nucleating agent, the proportion of crystalline portions around the plant fibers 2 increases. In other words, it has a pseudo-core-shell structure in which the plant fibers 2 can be considered as the core and the crystalline portions as the shell structure. This structure significantly suppresses the diffusion rate of fragrance components 3 from inside the plant fibers 2 to the main resin 1.

[0031] If the plant fiber content is less than 50%, the total amount of aromatic components decreases, making it impossible to maintain the sustained release of the aromatic fragrance for a long period of time. In addition, the overall crystallinity of the main resin decreases, reducing the inhibitory effect on the diffusion rate of aromatic components. If the plant fiber content is 90% or more, the main resin content is too low compared to the plant fiber content, making it impossible to encapsulate the plant fibers 2 within the main resin 1. As a result, a large amount of plant fibers 2 are exposed on the surface of the main resin, making it impossible to suppress the release of aromatic components 3. Furthermore, the low main resin content significantly reduces the fluidity of the composite resin composition, making it impossible to stably perform kneading and injection molding. For this reason, it is preferable that the plant fiber content in the composite resin molded article be within the aforementioned range.

[0032] The average particle size of the plant fibers 2 is preferably 1 μm or more and 3 mm or less, and more preferably 20 μm or more and 1 mm or less. If the average particle size is less than 1 μm, the size of the plant fibers is small, resulting in a small amount of aromatic components being held per fiber. Also, the surface area per fiber becomes very large, making it impossible to add it to the main resin at a high concentration. If the average particle size is greater than 3 mm, the plant fibers cannot be uniformly dispersed in the main resin, resulting in variations in the sustained release of aromatic components in the composite resin molded article. Therefore, it is preferable that the average particle size of the plant fibers 2 is within the above range.

[0033] The crystallinity of the main resin 1 is preferably 30% or more, and more preferably 60% or more. If the crystallinity of the main resin 1 is less than 30%, the proportion of amorphous parts is large, so the diffusion rate of the aromatic components cannot be suppressed to a sufficient extent, and the composite resin molded product cannot maintain sustained release over a long period of time. For this reason, it is preferable that the crystallinity of the main resin 1 be within the above range.

[0034] Preferably, the degree of crystallinity of the main resin 1 around the plant fibers in the composite resin molded body is 1.05 times or more than that of the portion consisting only of the main resin 1, and more preferably 1.10 times or more. If the crystallinity of the main resin surrounding the plant fibers is less than 1.05 times that of the portion containing only the main resin, a pseudo-core-shell structure cannot be formed by the plant fibers and the surrounding resin due to the low crystallinity of the main resin surrounding the plant fibers. In other words, aromatic components cannot be trapped within the plant fibers, and their release rate cannot be suppressed. Therefore, it is preferable that the crystallinity of the main resin 1 surrounding the plant fibers in the composite resin molded product is within the aforementioned range compared to the portion containing only the main resin 1.

[0035] The particle size variation of the plant fiber 2 is preferably Δd ≥ 6, and more preferably Δd ≥ 8. In this specification, Δd is defined as an index representing the particle size variation. Δd is the value obtained by dividing the d90 value of the particle size distribution by d10, and is defined by the following formula. Δd = d90 / d10 Note that d90 is a particle size where 90% of the particles in the particle size distribution are below this value, and d10 is a particle size where 10% of the particles in the particle size distribution are below this value.

[0036] Since the amount of aromatic compounds contained within plant fibers varies depending on their size, the release rate of aromatic compounds changes depending on the fiber size. When the particle size variation is Δd < 6, the variation in plant fibers is small, so the release rate of aromatic compounds from the plant fibers becomes constant, and the sustained release property decreases. For this reason, it is preferable that the particle size variation of the plant fiber 2 is Δd ≥ 6.

[0037] It is preferable that the fiber length direction of the plant fibers 2 in the skin layer of the composite resin molded article is oriented at an angle of 0° to 30° with respect to the composite resin surface. During the kneading process in the manufacturing of the composite resin molded article, the ends of the plant fibers 2 in the fiber length direction within the fiber surface are particularly defibrated. Compared to the non-defibrated portion, the defibrated portion has a larger surface area, and the release of aromatic components is accelerated. If the fiber length direction of the plant fibers in the surface skin layer is oriented at an angle greater than 30° with respect to the skin layer, the release of aromatic components in the direction of the skin layer is accelerated, and the sustained release of the aroma decreases. Therefore, it is preferable that the fiber length direction of the plant fibers 2 in the skin layer is oriented at an angle within the aforementioned range with respect to the surface of the composite resin molded article.

[0038] The thickness of the skin layer on the surface of the composite resin molded article is preferably 600 μm or less. When molded by injection molding, molten resin is injected into the mold, and the surface portion in contact with the mold is rapidly cooled, forming the skin layer. On the other hand, the internal core layer is formed while being slowly cooled. Since crystals grow as they cool slowly, the skin layer formed by rapid cooling has a low degree of crystallinity, while the core layer formed by slow cooling has a high degree of crystallinity. If the thickness of the skin layer is greater than 600 μm, the proportion of the skin layer portion with a low degree of crystallinity increases, making it difficult to suppress the release rate of fragrance components, and thus reducing the fragrance release properties. Therefore, the thickness of the skin layer on the surface of the composite resin molded article is preferably within the aforementioned range.

[0039] Preferred kneading equipment for the manufacturing method of composite resin molded articles includes kneaders, Banbury mixers, extruders, and roll kneaders. Among these, twin-screw kneaders and roll kneaders are more preferred. However, the kneading equipment is not limited to the above-mentioned equipment as long as it has a rotating body as a kneading means. Furthermore, since the aromatic components contained in plant fibers are volatile, it is preferable to knead at the lowest possible temperature. [Examples]

[0040] Figure 3A shows the conditions for Examples 1-8 and Comparative Examples 1-4, and Figure 3B shows the measurement results for Examples 1-8 and Comparative Examples 1-4.

[0041] (Example 1) A plant fiber-containing composite resin composition was produced by the following manufacturing method. As mentioned above, kneaders, Banbury mixers, extruders, roll kneaders, etc. can be used as the kneading equipment, but in this example, a twin-screw kneader was used.

[0042] Polypropylene was used as the main resin, and cypress powder, which was crushed using a pulverizer and had an average particle size of 50 μm with a particle size variation Δd of 6, was used as the plant fiber. These were weighed together in a mass ratio of 43:55:2 and dry-blended.

[0043] The dry-blended raw materials were supplied to the mixing device at a rate of 2 kg / h using a weight feeder. As mentioned above, a twin-screw mixer (JSW TEX30a) was used as the mixing device. The screw was of the medium-shear type. The composite resin discharged from the twin-screw mixer was hot-cut to produce plant fiber-containing composite resin pellets.

[0044] Test specimens of composite resin molded products were prepared using the prepared plant fiber-containing composite resin pellets and an injection molding machine (Japan Steel Works 180AD). The test specimen preparation conditions were: resin temperature 200°C, mold temperature 40°C, injection speed 60 mm / s, and holding pressure 80 MPa. The pellets were fed into the molding machine's screw via a hopper, and the rate of penetration was measured by the amount of pellets lost per unit time, confirming that it was constant. The shape of the test specimens was changed according to the evaluation items described below. A No. 1 dumbbell test specimen was prepared for elastic modulus measurement, and cup test specimens were prepared for sensory evaluation of aroma and sustained release evaluation. The obtained test specimens of plant fiber-containing composite resin molded products were evaluated by the following method.

[0045] [Evaluation criteria for composite resin molded products] (Aromatic sensory evaluation) Using the obtained cup-shaped test pieces, a sensory evaluation of the fragrance (aromatic sensory evaluation) test was conducted. Testers were asked to actually smell the fragrance of the test pieces and evaluate the pleasantness of the fragrance on a 7-point scale from 1 to 7 (1=very unpleasant, 2=unpleasant, 3=slightly unpleasant, 4=average, 5=slightly pleasant, 6=pleasant, 7=very pleasant), and the intensity of the fragrance on a 7-point scale from 1 to 7 (1=very weak, 2=weak, 3=slightly weak, 4=just right, 5=slightly strong, 6=strong, 7=very strong). Here, as a method for evaluating the sensory perception of fragrances, fragrances with a pleasantness rating of 1-4 were marked with ×, those with a rating of 5 with △, those with a rating of 6 with ○, and those with a rating of 7 with ◎. Fragrance strength ratings were marked with × for 1-2 and 6-7, △ for 3 and 5, and ○ for 4. Fragrances with a pleasantness rating of × were marked with × regardless of their strength. Fragrances with a pleasantness rating of △ and strength rating of × were marked with ×, and those with strength ratings of △ or ○ were marked with △. Fragrances with a pleasantness rating of ○ and strength rating of × were marked with ×, those with strength ratings of △ were marked with △, and those with strength ratings of ○ were marked with ○. Fragrances with a pleasantness rating of ◎ and strength rating of × were marked with ×, those with strength ratings of △ were marked with ○, and those with strength ratings of ○ were marked with ◎. The evaluation of the same test piece in Example 1 was a score of 6 for pleasantness of scent and 4 for scent intensity, and the evaluation result was ○.

[0046] (Evaluation of sustained aroma release) Using the obtained cup-shaped test pieces, a sustained-release fragrance evaluation test (fragrance sustained-release evaluation) was conducted. While normally left at room temperature, to conduct an accelerated test, the samples were placed in a small 60°C hot air dryer, and the fragrance intensity of the samples was evaluated every 24 hours. Testing in an environment with 60°C hot air is approximately 50 times more accelerated than testing in a normal room temperature environment. After 90 hours or more, fragrance intensity evaluations of 1-2 and 6-7 were marked as ×, 3 and 5 were marked as △, and 4 was marked as ○. The evaluation of the test specimen was 4, and the rating was ○. A rating of ◎ was given for samples with a fragrance intensity of 4 after 120 hours or more.

[0047] (Elastic modulus of composite resin molded articles) Tensile tests were conducted using the obtained dumbbell-shaped test specimen No. 1. Here, the elastic modulus was evaluated as follows: values ​​less than 1.9 GPa were marked with ×, values ​​between 1.9 GPa and 2.7 GPa were marked with △, values ​​between 2.7 GPa and 3.6 GPa were marked with ○, and values ​​of 3.6 GPa or higher were marked with ◎. The elastic modulus of the test specimen was 4.2 GPa, and its evaluation was excellent (◎).

[0048] (Degree of crystallinity of composite resin molded products) (Degree of crystallinity of composite resins) The melting (crystallization) peak was measured using differential scanning calorimeter (DSC) and the heat of fusion was calculated. The degree of crystallinity was calculated using the following formula. Crystallinity = (Measured heat of fusion / Heat of fusion of perfect crystal) × 100 Here, as a method for evaluating the degree of crystallinity, samples with less than 30% were marked with ×, samples with 30% or more but less than 60% were marked with ○, and samples with 60% or more were marked with ◎. The composite resin molded product had a crystallinity of 53%, and its evaluation was positive (○).

[0049] (Degree of crystallinity around the fiber) A portion of the obtained dumbbell-shaped test piece (No. 1) was cut out and observed using Raman spectroscopy. Samples where the degree of crystallinity of the resin around the plant fibers was less than 1.05 times that of the crystalline portion were marked with ×, and samples where it was 1.05 times or more were marked with ○. The degree of crystallinity of the resin surrounding the plant fibers in the test specimen was 1.12 times higher than that of the crystalline portion, and this was evaluated as "○".

[0050] (Orientation of fibers in the skin layer) A portion of the obtained dumbbell-shaped specimen (No. 1) was cut out, and polarized light microscopy measurements were performed on the cross-section. On the obtained polarized light microscopy image, the angle of the plant fibers in the skin layer in the direction of fiber length was measured, with the specimen surface set to 0°. An angle of 70° or more in the direction of fiber length of the plant fibers was marked with ×, 30° or less than 70° was marked with △, and 0° or more but less than 30° was marked with ○. The angle of the plant fibers in the skin layer of the test specimen was 10° in the direction of the fiber length, and its evaluation was positive (○).

[0051] (Thickness of the skin layer) A portion of the obtained dumbbell-shaped test specimen (No. 1) was cut out and subjected to polarized light microscopy measurements. The thickness of the skin layer was measured on the obtained polarized light microscopy image. If the skin layer thickness was greater than 600 μm, it was marked with an "X," and if it was 600 μm or less, it was marked with a "○." The skin layer thickness of the test specimen was 430 μm, and its evaluation was positive (○).

[0052] (Example 2) In Example 2, the amount of plant fiber was increased, and the weight ratio of main resin:plant fiber:dispersant was changed to 27:70:3. Plant fiber-containing composite resin pellets and molded articles were produced under the same conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0053] (Example 3) In Example 3, plant fibers with an average particle size of 1 mm, which is larger than that used in Example 1, were used. Cellulose fiber-containing composite resin pellets and molded articles were produced using the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0054] (Example 4) In Example 4, the injection molding conditions were changed to increase the mold temperature during injection molding compared to Example 1. All other material and process conditions were the same as in Example 1 to produce cellulose fiber-containing composite resin pellets and molded articles. The evaluation was also performed in the same manner as in Example 1.

[0055] (Example 5) In Example 5, plant fibers with a larger variation in fiber particle size Δd (Δd = 10) were used compared to Example 1. Cellulose fiber-containing composite resin pellets and molded articles were produced using the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0056] (Example 6) In Example 6, plant fibers with a particle size variation of Δd=2, which is smaller than in Example 1, were used. Plant fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0057] (Example 7) In Example 7, the injection molding conditions were changed compared to Example 1, with a higher resin temperature and a faster injection speed during injection molding. Cellulose fiber-containing composite resin pellets and molded articles were produced using the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0058] (Example 8) In Example 8, the injection molding conditions were changed to lower the resin temperature and slower the injection speed compared to Example 1. For all other material and process conditions, the plant fiber-containing composite resin pellets and molded articles were produced in the same manner as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0059] (Comparative Example 1) In Comparative Example 1, pulp was used that had been bleached for a sufficiently long time as a plant fiber to remove almost all residual components such as lignin and hemicellulose. Composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same way as in Example 1.

[0060] (Comparative Example 2) In Comparative Example 2, polystyrene (PS), an amorphous resin, was used as the main resin component. Cellulose fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0061] (Comparative Example 3) In Comparative Example 3, the amount of plant fiber was reduced compared to Example 1, and the weight ratio of main resin:plant fiber:dispersant was changed to 89:10:1. Plant fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also carried out in the same manner as in Example 1.

[0062] (Comparative Example 4) In Comparative Example 4, the amount of plant fiber was increased compared to Example 1, and the weight ratio of main resin:plant fiber:dispersant was changed to 2.5:95:2.5. The plant fiber-containing composite resin pellets and molded articles were produced under the same material and process conditions as in Example 1. The evaluation was also performed in the same manner as in Example 1.

[0063] The measurement results for each of Examples 1-8 and Comparative Examples 1-4 are shown in the table in Figure 3B.

[0064] In Example 2, where the amount of plant fiber was increased, the fiber reinforcement effect by the plant fiber was greater than in Example 1, resulting in an elastic modulus of 5.1 GPa. The increased amount of plant fiber also increased the degree of crystallinity to 63%. Furthermore, the increased amount of plant fiber increased the amount of aromatic components, resulting in a positive result in both the aromatic sensory evaluation and the sustained-release evaluation.

[0065] In Example 3, which used fibers with an average particle size of 1 mm, the fiber size was larger compared to Example 1, and the amount of aromatic components contained inside each fiber increased, resulting in improved sustained release properties and an excellent rating for aromatic sustained release.

[0066] In Example 4, where the mold temperature during injection molding was increased, the composite resin cooled more slowly compared to Example 1, resulting in an increased degree of crystallinity to 64%, and its aroma release performance was evaluated as excellent (◎).

[0067] In Example 5, which used plant fibers with a particle size variation Δd=10, the amount of aromatic components contained varied depending on the fiber size. Consequently, the release period of aromatic components from fibers of each size differed, resulting in improved sustained fragrance release and an excellent evaluation result.

[0068] In Example 6, which used plant fibers with a fiber particle size variation Δd=2, the fragrance sustained-release evaluation result was △ because the fiber size was almost the same and the release period of the fragrance components was also almost the same.

[0069] In Example 7, where the resin temperature during injection molding was increased and the injection speed was increased, the thickness of the skin layer was reduced compared to Example 1, and the core layer increased accordingly. As a result, the release rate of the fragrance components decreased, and the evaluation result for sustained release was excellent.

[0070] In Example 8, where the resin temperature during injection molding was lowered and the injection speed was reduced, the skin layer thickness increased compared to Example 1. As a result, the proportion of the core layer relative to the total resin decreased, and the release of fragrance components could not be suppressed, resulting in a △ evaluation result for sustained release. Based on the above, Examples 2, 3, 4, 5, and 7 achieved results equivalent to or better than Example 1 in all tests.

[0071] Comparative Example 1, which used pulp from which residual components such as lignin and hemicellulose had been almost completely removed as plant fibers, contained almost no aromatic components. Therefore, in the aromatic sensory evaluation, the pleasantness of the scent was rated as 5, and the intensity of the scent was rated as 1, resulting in an evaluation result of ×.

[0072] In Comparative Example 2, which used polystyrene (PS), an amorphous resin, as the main resin component, the release rate of the fragrance components could not be suppressed due to the absence of crystalline components in the resin, resulting in a negative (×) evaluation result for sustained release.

[0073] In Comparative Example 3, where the weight ratio of plant fibers to all raw materials was reduced, the amount of cellulose fiber was small, resulting in a low degree of crystallinity and a low total amount of aromatic components. Consequently, the sensory evaluation of the fragrance was unsuccessful. Furthermore, the fiber reinforcement effect on the composite resin was reduced, and the modulus of elasticity was 2.0 GPa.

[0074] In Comparative Example 4, where the weight ratio of plant fiber to the total raw materials was increased, the viscosity became too high due to the large amount of fiber, placing a heavy load on the equipment and making stable kneading and molding impossible. As a result, test specimens could not be prepared and evaluation could not be performed.

[0075] Based on the above evaluation, the use of amorphous resin resulted in reduced long-term sustained release properties. When the plant fiber concentration was low, the amount of aromatic components decreased, resulting in insufficient fragrance. When the plant fiber concentration was too high, stable kneading and molding were not possible. From the above, it was found that by using plant fibers containing aromatic components and crystalline resin, and by ensuring that the plant fiber content is between 50% and 90% by mass, composite resin molded articles can be produced stably, exhibit high mechanical strength, and have long-term aromatic sustained-release properties.

[0076] Furthermore, this disclosure includes appropriately combining any of the various embodiments and / or examples described above, and the effects of each embodiment and / or example can be achieved. [Industrial applicability]

[0077] The composite resin molded article according to the present invention has superior mechanical strength compared to conventional general-purpose resins, possesses sensory characteristics such as color, texture, and fragrance derived from plant materials, and provides a molded article with long-term fragrance release properties. Because the composite resin molded article according to the present invention can have long-term fragrance release properties that are less affected by the environment, it can impart a relaxation effect to everyday items. Furthermore, due to its superior mechanical strength, it can be used in home appliance casings, building materials, and automotive components. [Explanation of Symbols]

[0078] 1. Main resin 2. Plant Fibers 3 Aromatic ingredients 4. Dispersant 10 Composite resin molding 11 Amorphous part 12 Crystal part 13 Skin Layers 14 Core Layers

Claims

1. It contains a main resin, plant fibers made from coniferous trees, and a dispersant. The aforementioned plant fiber contains aromatic components including volatile pinene, cadinol, or hinokiol. The main resin is a crystalline resin, When the total amount of the main resin, the plant fibers, and the dispersant is 100% by mass, the content of the plant fibers is 50% by mass or more and 90% by mass or less, A composite resin molded article wherein, in the particle size distribution of the plant fibers, the particle size variation Δd, expressed as Δd = d90 / d10 using particle size d90 where the proportion of particles less than or equal to that value is 90%, and particle size d10 where the proportion of particles less than or equal to that value is 10%, is 6 or more.

2. The composite resin molded article according to claim 1, wherein the average particle size of the plant fibers is 1 μm or more and 3 mm or less.

3. The composite resin molded article according to claim 1 or 2, wherein the crystallinity of the main resin is 30% or more.

4. The composite resin molded article according to any one of claims 1 to 3, wherein the degree of crystallinity of the main resin around the plant fibers in the composite resin molded article is 1.05 times or more than that of the portion consisting only of the main resin.

5. The composite resin molded article according to any one of claims 1 to 4, wherein the fiber length direction of the plant fibers in the skin layer of the composite resin molded article is oriented at an angle of 0° to 30° with respect to the surface of the composite resin molded article.

6. The composite resin molded article according to any one of claims 1 to 5, wherein the thickness of the skin layer on the surface of the composite resin molded article is 600 μm or less.

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