Resin molded article

Abstract

The present invention is a resin molded article made of a resin material containing a resin and a fiber-reinforced material, wherein: the proportion of the fiber-reinforced material having a length of more than 0 and less than 3000 μm is 10-100%; a textured pattern including a plurality of protrusions is imparted to at least a portion of the surface; and the maximum length of the bases of the protrusions is more than 0 and less than Lcos(20°) μm, with L being the average fiber length of the fiber-reinforced material.

Description

Resin molded product

[0001] The present invention relates to a resin molded product.

[0002] There is known a resin panel which is produced by press molding a thermoplastic resin containing long glass fibers, has a squeezed pattern on its surface, the interval between corresponding valley portions between the convex portions constituting the squeezed pattern is 3 mm or less, and the depth of the valley portion is 50 μm or more (Patent Document 1). According to the resin panel, it is said that the long glass fibers are not exposed on the surface of the base material and the appearance of the panel is not impaired.

[0003] Japanese Utility Model Laid-Open No. 05-082513

[0004] In the above prior art, since relatively short glass fibers are unevenly distributed near the surface of the resin molded product, portions that appear relatively lighter in color due to the glass fibers appear on the surface of the resin molded product, and there is a problem that the color of the surface of the resin molded product becomes non-uniform.

[0005] The problem to be solved by the present invention is to provide a resin molded product capable of suppressing the surface color from becoming non-uniform due to a reinforcing material such as glass fibers.

[0006] In the present invention, it is made of a resin material containing a resin and a fiber reinforcing material, the ratio of the fiber reinforcing material having a length exceeding 0 and less than 3000 μm among the fiber reinforcing materials is 10 to 100%, and at least a part of the surface has a plurality of convex portions. In the resin molded product provided with a dimpled pattern, the maximum length of the base of the convex portion is made to exceed 0 and less than Lcos(20°) μm when the average fiber length of the fiber reinforcing material is L, thereby solving the above problem.

[0007] According to the present invention, it is possible to suppress the surface color of the resin molded product from becoming non-uniform due to a reinforcing material such as glass fibers.

[0008] This is a flowchart showing an example of the procedure for manufacturing a resin molded product according to the present invention. This is a schematic cross-sectional view showing an example of a textured pattern applied to the surface of a resin molded product according to the present invention. This is a schematic cross-sectional view showing another example of a textured pattern applied to the surface of a resin molded product according to the present invention. This is a front view showing an example of an inclined surface of a resin molded product according to the present invention. This is a schematic cross-sectional view showing yet another example of a textured pattern applied to the plan view showing an example of a mold made by the procedure shown in Figure 1. This is a photograph showing an example of a resin molded product according to the present invention. This is a photograph showing another example of a resin molded product according to the present invention. This is a photograph showing an example of a resin molded product according to a comparative example of the present invention. This is a cross-sectional view of the main part of the resin molded product shown in Figure 9A. This is a cross-sectional view of the main part of the resin molded product shown in Figure 9B. This is a cross-sectional view of the main part of the resin molded product shown in Figure 9C. This is a histogram showing the state of glass fibers in the thickness direction of the resin molded product shown in Figure 9C.

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] [Shape and Material of Resin Molded Products] The resin molded products according to the present invention are, for example, resin molded products for vehicles, and are interior parts of vehicles that are molded from resin material. Examples of interior parts include instrument panels, center console panels, door inner trims, and other interior parts that are installed in areas visible to the occupants. The shape of the resin molded products is not particularly limited, as long as they can be appropriately molded by injection molding or the like.

[0011] The resin material constituting a molded resin product includes a resin and a reinforcing material. The resin may be a thermoplastic resin or a thermosetting resin. Thermoplastic resins include crystalline resins and amorphous resins. Examples of resins include polypropylene (PP), polyurethane (PU), polyamide (PA), polyacetal (POM), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), and combinations thereof (polymer alloys).

[0012] Reinforcements are materials that improve the strength and elastic modulus of resin materials. Reinforcements include fiber reinforcements such as glass fibers and carbon fibers, plate-like reinforcements such as mica and talc, and granular reinforcements such as glass beads. Resin materials may also contain stabilizers such as antioxidants and UV absorbers, functional agents such as flame retardants and antistatic agents, and colorants such as carbon black. The reinforcements (and other additives) are uniformly mixed with the resin using a melting and kneading machine such as a Banbury mixer or kneader. The ratio of resin to reinforcements (and other additives) can be appropriately set depending on the application of the resin material.

[0013] [Procedure for Manufacturing Resin Molded Products] Figure 1 is a flowchart showing an example of the procedure for manufacturing resin molded products according to the present invention. As shown in Figure 1, the procedure for manufacturing resin molded products is divided into a mold manufacturing stage in which a mold is made, and an injection molding stage in which the resin molded product is molded using the mold. The mold is a mold made of steel material such as azured steel or pre-hardened steel.

[0014] In the mold making stage, a mold is designed according to the desired shape (step S1), cutting is performed using an NC machine tool or the like (step S2), and finishing processes such as electrical discharge machining and polishing are performed (step S3). In addition, a textured finish is applied to the part of the mold that corresponds to the surface of the resin molded product (hereinafter also called the cavity) (step S4), and finally the gloss is adjusted (step S5). Processing methods such as etching and sandblasting are used for the textured finish and gloss adjustment.

[0015] In the injection molding stage, the thermoplastic resin material is plasticized by a heating cylinder (step S11), the molten resin material is injected into the cavity (step S12), and holding pressure is applied to the resin material in the cavity until the gate portion into which the resin material flows into the cavity solidifies (step S13). The resin material filled into the cavity is cooled until the surface solidifies (step S14), and then removed from the mold (step S15).

[0016] Furthermore, the resin molded product according to the present invention may be manufactured by hot press molding or by RTM (Resin Transfer Molding) molding. Figure 1 shows, as an example, the procedure for molding a resin molded product by hot press molding. In hot press molding, first, the SMC (Sheet Molding Compound) material is placed in the cavity of the mold (step S21), the sheet softened by heating is pressed (step S22), and after cooling to a state where it can be removed from the mold, it is removed from the mold (step S23).

[0017] [Shape of the textured pattern] The surface of the resin molded product according to the present invention is given a textured pattern. The textured pattern is a pattern that imitates the leather pattern of real leather and consists of a collection of generally elliptical unit patterns. The unit patterns are elliptical or similarly elongated oval-shaped protrusions (e.g., frustums) and are formed to protrude from the surface of the resin molded product. Multiple unit patterns are randomly arranged in the parts of the resin molded product to which the textured pattern is given. In addition, the size of each unit pattern is also random.

[0018] A textured surface can be created, for example, by forming irregularities on the surface of the cavity of an injection molding die, and then filling the cavity with molten resin material to transfer the irregularities of the cavity to the surface of the molded resin product. A cavity is a hollow portion that has a shape corresponding to the shape of the molded resin product and is filled with molten resin material. The process of forming irregularities on the surface of the cavity that correspond to the textured surface is performed by the texturing process (step S4) shown in Figure 1. Alternatively, the textured surface may be directly applied to the smooth surface of the molded resin product by laser processing or the like.

[0019] The resin molded article according to the present invention is made of a resin material containing resin and fiber reinforcement, the proportion of fiber reinforcement having a length greater than 0 and less than 3000 μm is 10 to 100%, and at least a part of the surface of the resin molded article is given a textured pattern including a plurality of protrusions. The proportion of fiber reinforcement having a length greater than 0 and less than 3000 μm is determined, for example, from the distribution of fiber lengths measured according to the ISO 22314:2006 standard.

[0020] A convex portion refers to a projection that protrudes from the surface of a resin molded product, and a base portion refers to the root of the convex portion. The maximum length of the base portion refers to the longest distance between any two points on the circumference of the base portion (for example, on the outer circumference of the root of the convex portion). The maximum length of the base portion is measured using an optical microscope or an electron microscope. For example, the maximum length of the base portion is measured using a three-dimensional shape measuring machine such as the VR6000 (manufactured by Keyence Corporation). Alternatively, the maximum length of the base portion may be measured using a laser microscope (blue laser type) such as the LEXT OLS5100 (manufactured by Olympus Corporation). The maximum length of the base portion of the convex portion is greater than 0 and less than Lcos(20°) μm, where L is the average fiber length of the fiber-reinforced material, and may be greater than 0 and less than 2000 μm.

[0021] The above-mentioned cos(20°) is based on the fact that the inventors have confirmed that in resin molded products manufactured by injection molding, the inferior angle between the fiber reinforcing material and the flow direction is a maximum of 20° in a cross section parallel to the thickness direction of the resin molded product (hereinafter also simply referred to as the thickness direction) and the flow direction of the resin material (hereinafter also simply referred to as the flow direction) (or a cross section that is parallel to the thickness direction and along the flow direction). In other words, if the maximum length of the base of the protrusion is less than Lcos(20°) μm (where L is the average fiber length), even if the fiber reinforcing material is inclined with respect to the flow direction in a cross section parallel to the thickness direction and the flow direction (hereinafter also referred to as a specific cross section), it is possible to suppress the fiber reinforcing material from entering the interior of the protrusion.

[0022] The marginal angle between the fiber reinforcement and the flow direction in a specific cross-section can be determined, for example, by extracting the portion of the fiber reinforcement from an image taken of the specific cross-section using high-resolution X-ray CT (Computed Tomography), utilizing the color difference between the resin and the fiber reinforcement, and then calculating the marginal angle with the flow direction for each extracted portion. For example, a TM-1000 (manufactured by Hitachi High-Technologies Corporation) is used as the high-resolution X-ray CT device. The resolution is, for example, 0.9 μm. The process of extracting the portion of the fiber reinforcement from the image and the process of calculating the marginal angle with the flow direction are performed using image analysis software such as FiberShape (manufactured by IST AG).

[0023] The average fiber length of the fiber reinforcement material is calculated, for example, from the distribution of fiber lengths measured according to the ISO 22314:2006 standard. The average fiber length may be the number-average fiber length or the length-average fiber length. Alternatively, the average fiber length of the fiber reinforcement material may be calculated by taking a picture of a specific cross-section using high-resolution X-ray CT, extracting the portion of the fiber reinforcement material from the captured image using the color difference between the resin and the fiber reinforcement material, and calculating the average length of the extracted portion. In this case, in the image taken by high-resolution X-ray CT, the resin molded product may be divided into 14 layers along the thickness direction, and the length of approximately 200 fiber reinforcements contained in each of the 7 layers on one side may be measured. The average length of the fiber reinforcement material is measured, for example, from the relative relationship between the number of pixels of fiber length and the scale. For example, a TM-1000 (manufactured by Hitachi High-Technologies Corporation) is used as the high-resolution X-ray CT device. The resolution is, for example, 0.9 μm. The processes of extracting the fiber-reinforced material from the image and calculating the average length of the extracted portion are performed using image analysis software such as FiberShape (manufactured by IST AG).

[0024] Figure 2 is a schematic cross-sectional view showing an example of a textured pattern (hereinafter also simply referred to as the textured pattern) applied to the surface of a resin molded product according to the present invention. The X and Y axes shown in Figure 2 correspond to the horizontal and vertical axes, respectively, when the textured pattern is viewed in plan. The Z axis direction corresponds to the direction in which the resin molded product moves when it is released from the mold (hereinafter also referred to as the release direction). The cross-section shown in Figure 2 is a cross-section parallel to the XZ plane along the release direction. For explanatory purposes, in Figures 2-3 and 5-7, the length in the Z axis direction is exaggerated relative to the length in the X axis direction. Also, in Figures 2-7, if the same configuration is shown multiple times in one drawing, not all configurations are assigned reference numerals, and some of the duplicate reference numerals are omitted.

[0025] As shown in Figure 2, the surface of the resin molded product 10 according to the present invention is given a textured pattern including a plurality of first protrusions 11. The maximum length of the first base portion 11a of the first protrusion 11 is greater than 0 and less than 500 μm. Furthermore, in order to enable proper molding of the resin molded product 10, the lower limit of the maximum length of the first base portion 11a may be 50 μm or more, 100 μm or more, or 200 μm or more.

[0026] The maximum height H1 of the first protrusion 11, with the first base 11a as the reference position, can be set to an appropriate value within the range that allows the resin molded product 10 to be properly released from the mold, for example, 20 to 200 μm. The height of the protrusion is measured with the base or the surface of the resin molded product as the reference position. The maximum height of the protrusion refers to the longest distance in the release direction from the surface of the base or resin molded product to the tip of the protrusion. The maximum height of the protrusion is measured using an optical microscope or an electron microscope. For example, the maximum height of the protrusion is measured using a 3D shape measuring machine such as the VR6000 (manufactured by Keyence Corporation) or a laser microscope (blue laser type) such as the LEXT OLS5100 (manufactured by Olympus Corporation).

[0027] When the resin molded product is manufactured by injection molding, the maximum height H1 of the first protrusion 11 with the first base 11a as the reference position may be greater than 0 and less than Lcos(20°)tan(20°) when the average fiber length of the fiber reinforcing material is L. Even if the fiber reinforcing material is inclined with respect to the flow direction in a specific cross section, if the maximum height H1 of the first protrusion 11 is less than Lcos(20°)tan(20°), the fiber reinforcing material is prevented from entering the interior of the first protrusion 11.

[0028] The textured pattern may include a plurality of first protrusions and a plurality of second protrusions that are different from the first protrusions. The maximum length of the second base of the second protrusion is Lcos(20°) μm or more, where L is the average fiber length of the fiber-reinforced material, and the first protrusions may be formed on the surface of the second protrusions. In this case, the maximum height of the first protrusion with the first base as the reference position may be 10 to 100% of the maximum height of the second protrusion with the second base as the reference position.

[0029] Figure 3 is a schematic cross-sectional view showing another example of a textured pattern. As shown in Figure 3, a plurality of second protrusions 12 are formed on the surface of the resin molded product 10, and a first protrusion 13 is formed on the surface of the second protrusions 12. The maximum length of the second base 12a of the second protrusion 12 is 2000 to 3500 μm, and the maximum length of the first base 13a of the first protrusion 13 is greater than 0 and less than 500 μm. Furthermore, the maximum height H3 of the first protrusion 13 with the first base 13a as the reference position is 10 to 30% of the maximum height H2 of the second protrusion 12 with the second base 12a as the reference position.

[0030] If a first protrusion is formed on an inclined surface (hereinafter simply referred to as an inclined surface) that forms a less than predetermined angle relative to the depth direction of the resin molded product, the maximum height of the first protrusion provided on the inclined surface, with the first base as the reference position, may be lower than the maximum height of the first protrusion provided on a surface other than the inclined surface, with the first base as the reference position. The depth direction of the resin molded product is the height direction of the resin molded product and is the demolding direction. The predetermined angle can be set to an appropriate value within the range in which the resin molded product with a textured pattern can be smoothly demolded, for example, greater than 0 and 10°.

[0031] Figure 4 is a front view showing an example of a mold manufactured by the procedure shown in Figure 1. The mold 20 shown in Figure 4 is an injection molding die and comprises a fixed mold 21 fixed to a molding machine and a movable mold 22 that moves in the demolding direction relative to the fixed mold 21. When molten resin material is filled into the cavity formed between the fixed mold 21 and the movable mold 22 to form the resin molded product 10 shown in Figure 4, the surface 10a enclosed by the dashed line is the inclined surface. In the example shown in Figure 4, if a first protrusion is provided on the inclined surface 10a, the maximum height of the first protrusion on the inclined surface 10a is made lower than the maximum height of the first protrusion provided on surfaces other than the inclined surface 10a.

[0032] If a resin molded product is provided with a first protrusion and a second protrusion, at least one of a third protrusion and a recess may be formed between adjacent second protrusions. The maximum length of the third base of the third protrusion shall be greater than 0 and less than Lcos(20°) μm, where L is the average fiber length of the fiber-reinforced material, and the maximum length of the bottom surface of the recess facing the opening shall be greater than 0 and less than Lcos(20°) μm, where L is the average fiber length of the fiber-reinforced material. The maximum length of the bottom surface refers to the longest distance between any two points on the circumference of the bottom surface. The maximum length of the bottom surface is measured using an optical microscope or an electron microscope. For example, the maximum length of the bottom surface is measured using a three-dimensional shape measuring machine such as VR6000 (manufactured by Keyence Corporation) or a laser microscope (blue laser type) such as LEXT OLS5100 (manufactured by Olympus Corporation).

[0033] Furthermore, the maximum height of the third protrusion with the third base as the reference position may be 10 to 100% of the maximum height of the second protrusion with the second base as the reference position. Similarly, the maximum depth from the opening of the recess to the bottom surface opposite the opening may be 10 to 100% of the maximum height of the second protrusion with the second base as the reference position. The maximum depth of the recess refers to the longest distance in the demolding direction from the opening of the recess to the bottom surface opposite the opening. The maximum depth of the recess is measured using an optical microscope or an electron microscope. For example, the maximum depth of the recess is measured using a three-dimensional shape measuring machine such as the VR6000 (manufactured by Keyence Corporation) or a laser microscope (blue laser type) such as the LEXT OLS5100 (manufactured by Olympus Corporation).

[0034] Figure 5 is a schematic cross-sectional view showing yet another example of a textured pattern, illustrating a modified version of the textured pattern shown in Figure 3. As shown in Figure 5, a plurality of second protrusions 12 are formed on the surface of the resin molded product 10, and recesses 14 are formed between adjacent second protrusions 12. The maximum length of the bottom surface 14b of the recess 14, opposite the opening 14a, is greater than 0 and less than 500 μm. The maximum depth D1 of the recess 14 from the opening 14a to the bottom surface 14b is 10 to 30% of the maximum height H2 of the second protrusion 12 with the second base 12a as the reference position. Furthermore, if a third protrusion is provided instead of a recess 14 in the example shown in Figure 5, the maximum length of the third base of the third protrusion is greater than 0 and less than 500 μm, and the maximum height of the third protrusion with the third base as the reference position is 10 to 30% of the maximum height H2 of the second protrusion 12 with the second base 12a as the reference position.

[0035] The textured pattern may consist of relatively large protrusions with recesses formed therein. For example, if a textured pattern consisting of multiple protrusions is applied to at least a portion of the surface of a resin molded product, and the maximum length of the base of the protrusions is 2000 μm or more, then recesses may be formed in the protrusions where the maximum length of the bottom surface opposite the opening is greater than 0 and less than 2000 μm. Furthermore, the maximum depth of the recess with the opening as the reference position may be 10 to 100% of the maximum height of the protrusion with the base as the reference position.

[0036] Figure 6 is a schematic cross-sectional view showing yet another example of a textured pattern. As shown in Figure 6, a plurality of protrusions 15 are formed on the surface of the resin molded product 10, and a plurality of recesses 16 are formed in the protrusions 15. The maximum length of the base 15a of the protrusions 15 is 2000 to 3500 μm, and the maximum length of the bottom surface 16b opposite the opening 16a is greater than 0 and less than 500 μm. Also, the maximum depth D2 of the recess 16 with the opening 16a as the reference position is 50 to 90% of the maximum height H4 of the protrusions 15 with the base 15a as the reference position.

[0037] If the protrusion 15 shown in Figure 6 is formed on an inclined surface, then, similar to the example shown in Figure 4, the maximum depth D2 of the recess 16 of the protrusion 15 provided on the inclined surface, with the opening 16a as the reference position, may be made smaller than the maximum depth D2 of the recess 16 of the protrusion 15 provided on a surface other than the inclined surface, with the opening 16a as the reference position.

[0038] Furthermore, in the resin molded product 10 shown in Figure 6, at least one of a protrusion different from the protrusion 15 (hereinafter also referred to as a different protrusion) and a recess different from the recess 16 (hereinafter also referred to as a different recess) may be formed between adjacent protrusions 15. The maximum length of the base of the different protrusion shall be greater than 0 and less than 2000 μm, and the maximum length of the bottom surface of the different recess facing the opening shall be greater than 0 and less than 2000 μm. The maximum height of the different protrusion with the base of the different protrusion as the reference position may be 10 to 100% of the maximum height of the protrusion with the base of the protrusion as the reference position. Similarly, the maximum depth from the opening of the different recess to the bottom surface facing the opening may be 10 to 100% of the maximum height of the protrusion with the base of the protrusion as the reference position.

[0039] Figure 7 is a schematic cross-sectional view showing yet another example of a textured pattern, illustrating a modified version of the textured pattern shown in Figure 6. As shown in Figure 7, a plurality of protrusions 15 are formed on the surface of the resin molded product 10, and different protrusions 17 are formed between adjacent protrusions 15. The maximum length of the base 17a of the different protrusions 17 is greater than 0 and less than 500 μm. Furthermore, the maximum height H5 of the different protrusions 17 with the base 17a of the different protrusions 17 as the reference position is 10 to 30% of the maximum height H4 of the protrusions 15 with the base 15a of the protrusions 15 as the reference position. In addition, if different recesses are provided instead of different protrusions 17 in the example shown in Figure 7, the maximum length of the bottom surface opposite the opening of the different recess is greater than 0 and less than 500 μm, and the maximum depth from the opening of the different recess to the bottom surface is 10 to 30% of the maximum height H4 of the protrusions 15 with the base 15a of the protrusions 15 as the reference position.

[0040] The effect of the textured pattern according to the present invention will be explained with reference to examples. Figure 8 is a plan view showing an example of an injection molding die manufactured by the procedure shown in Figure 1. For illustrative purposes, Figure 8 shows only a cavity 30 having a shape corresponding to the shape of the resin molded product and into which molten resin material is filled, and a gate 31 into which the molten resin material flows into the cavity 30.

[0041] The cavity 30 is plate-shaped, with a length of 150 mm in the X-axis direction, a length of 105 mm in the Y-axis direction, and a length (thickness) of 3 mm in the Z-axis direction. The gate 31 is a fan gate, with a gate width (length in the Y-axis direction) of 40 mm and a gate thickness (length in the Z-axis direction) of 1.5 mm. The molten resin material flows in the direction of arrow 31a and enters the cavity 30.

[0042] In this embodiment, three molds as shown in Figure 8 were prepared, and the surface of the cavity 30 of each mold was etched to form irregularities corresponding to the textured pattern. Specifically, irregularities corresponding to the textured pattern shown in Figure 3 were formed on the surface of the cavity 30 of mold A, and irregularities corresponding to the textured pattern shown in Figure 6 were formed on the surface of the cavity 30 of mold B. In addition, irregularities corresponding to the textured pattern consisting of protrusions with a maximum base length of 2000 to 3500 μm were formed on the surface of the cavity 30 of mold C, as a comparative example of the present invention. Three types of resin molded products were then manufactured by injection molding using molds A to C.

[0043] The resin material used for injection molding was glass fiber reinforced polypropylene containing a propylene homopolymer (CAS registration number: 9003-07-0) as the base material, glass fibers (CAS registration number: 65997-17-3) as the fiber reinforcement, carbon black (CAS registration number: 1333-86-4) as the colorant, ethylene propylene polymer (CAS registration number: 9010-79-1) as the diluent, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione as the antioxidant. The glass fibers were present at 30% by weight when the total resin material is considered to be 100% by weight.

[0044] The injection molding machine used was the FN2000-25A (manufactured by Nissei Plastic Industrial Co., Ltd.), an electric molding machine with a maximum clamping force of 110 tons class. The maximum injection speed of the molding machine was 100 mm / s, the maximum injection pressure was 220 MPa, the clamping force was 1098 kN, and the screw diameter was 35 mm. The melting temperature of the resin material was set at 235 °C, and the temperature of the mold was set at 30 °C for both the fixed side and the movable side. The injection time, holding pressure, and holding time were set at 1 second, 30 MPa, and 2 seconds, respectively.

[0045] Photographs of the three types of resin molded products produced are shown in FIGS. 9A to 9C. FIGS. 9A to 9C show the portions corresponding to the range 30a in FIG. 8 among the photographs taken from the direction of the resin molded product in plan view. These photographs were taken using a VR6000 (manufactured by Keyence Corporation), a three-dimensional shape measuring machine. Also, schematic cross-sectional views showing the state of the glass fibers of the resin molded products shown in FIGS. 9A to 9C are shown in FIGS. 10A to 10C.

[0046] FIG. 9A is a photograph of a resin molded product produced using mold A. The surface of the resin molded product 10 shown in FIG. 9A is black and uniform, and the occurrence of bright portions that appear whiter than the surroundings is suppressed. Also, the embossed pattern applied to the resin molded product 10 shown in FIG. 9A is enlarged and shown at the lower right of FIG. 9A. FIG. 10A is a schematic cross-sectional view showing the state of the glass fibers GF of the resin molded product 10 shown in FIG. 9A. As shown in FIG. 10A, in the resin molded product 10 shown in FIG. 9A, since the glass fibers GF do not enter the inside of the first convex portion 13, the glass fibers GF do not unevenly distribute near the surface of the resin molded product 10 due to the first convex portion 13 formed on the surface of the second convex portion 12. Thereby, it is suppressed that the color of the surface of the resin molded product 10 becomes non-uniform.

[0047] Fig. 9B is a photograph of a resin molded product produced using the mold B. The surface of the resin molded product 10 shown in Fig. 9B is black and uniform, similar to the resin molded product 10 shown in Fig. 9A. The embossed pattern applied to the resin molded product 10 shown in Fig. 9B is enlarged and shown at the lower right of Fig. 9B. Fig. 10B is a schematic cross-sectional view showing the state of the glass fiber GF of the resin molded product 10 shown in Fig. 9B. As shown in Fig. 10B, in the resin molded product 10 shown in Fig. 9B, due to the recess 16 formed in the convex portion 15, the glass fiber GF does not enter the surface side from the bottom surface 16b of the recess 16, so the glass fiber GF does not unevenly distribute near the surface of the resin molded product 10. Thereby, it is suppressed that the color of the surface of the resin molded product 10 becomes non-uniform.

[0048] Fig. 9C is a photograph of a resin molded product produced using the mold C. On the surface of the resin molded product 10x shown in Fig. 9C, there are a dark portion A1 that appears black due to carbon black, which is a colorant, and a bright portion A2 that appears whiter than the surrounding dark portion A1 due to glass fibers unevenly distributed near the surface. The embossed pattern applied to the resin molded product 10x shown in Fig. 9C is enlarged and shown at the lower right of Fig. 9C. Fig. 10C is a schematic cross-sectional view showing the state of the glass fiber GF of the resin molded product 10x shown in Fig. 9C. As shown in Fig. 10C, in the resin molded product 10x shown in Fig. 9C, the glass fiber GF enters the inside of the convex portion 10y and unevenly distributes near the surface of the resin molded product 10x. In the portion where the glass fiber GF unevenly distributes near the surface, the color of the surface of the resin molded product 10x appears relatively light (or relatively white), so the color of the surface of the resin molded product 10x becomes non-uniform.

[0049] It has been confirmed by the inventors that the glass fiber GF tends to unevenly distribute near the surface when the injection speed of the resin material is set to a relatively slow speed, when the melting temperature of the resin material and / or the temperature of the mold is set to a relatively low temperature, when the flow length of the resin material is relatively long, and the like.

[0050] The state of the glass fibers in the thickness direction of the dark area A1 and the bright area A2 shown in Figure 9C was measured using a high-resolution X-ray CT scanner, the TM-1000 (manufactured by Hitachi High-Technologies Corporation). First, samples with a length of 10 mm in the X-axis direction and a length of 2.5 mm in the Y-axis direction (width direction) were cut from each of the dark area A1 and the bright area A2 of the resin molded product 10x shown in Figure 9C using an electric saw. The length (thickness) of the sample in the Z-axis direction was 3 mm. Next, the side surface of the sample (the surface parallel to the XZ plane) was polished with 800-grit emery paper and coated with Au-Pb using an ion sputtering device, the E-1010 (manufactured by Hitachi High-Technologies Corporation). Next, the side surface of the sample was photographed at 40x magnification from the positive Y-axis direction to the negative Y-axis direction using the TM-1000. Next, using the image analysis software FiberShape (manufactured by IST AG), the glass fiber portion was extracted from the side view image of the captured sample. The sample was then divided into 100 μm regions along the thickness direction, and the length of the glass fibers contained in each region was measured.

[0051] Figure 11 is a histogram showing the distribution of glass fiber lengths in the thickness direction of the resin molded product 10x, obtained from the glass fiber lengths measured by the method described above. The histograms on the left and right sides of Figure 11 show the state of the glass fibers in the light area A2 and the dark area A1 shown in Figure 9C, respectively. The histograms on the top, middle, and bottom of Figure 11 show the state of the glass fibers at a depth of 100 μm from the surface of the resin molded product 10x (the region from the surface to a depth of 100 μm), at a depth of 200 μm from the surface of the resin molded product 10x (the region from the surface to a depth of 100 to 200 μm), and at a depth of 400 μm from the surface of the resin molded product 10x (the region from the surface to a depth of 300 to 400 μm), respectively. In each histogram shown in Figure 11, the horizontal axis represents the fiber length of the glass fibers (in μm), and the vertical axis represents the frequency of detection of glass fibers per unit area (i.e., the number of glass fibers).

[0052] As shown in Figure 11, it was confirmed that glass fibers of a certain fiber length were more abundant in the bright area A2 than in the dark area A1 at the same depth. Furthermore, it was confirmed that in both the bright area A2 and the dark area A1, at all depths, glass fibers with a fiber length of 500 to 1000 μm were the most abundant. In addition, the glass fiber portion was extracted from the side view image of the captured sample using the image analysis software FiberShape (manufactured by IST AG), and the orientation of the glass fibers near the surface of the resin molded product 10x (in the range from the surface of the resin molded product 10x to a depth of 2000 μm) was observed. As a result, it was confirmed that the inferior angle α between the glass fibers and the flow direction (X-axis direction) on the side view parallel to the XZ plane, which is a specific cross-section, is 0 to 20°, as shown in Figure 10C.

[0053] Considering the state of the glass fibers shown in Figure 11, by setting the maximum length of the base (first base) of the convex portion (first convex portion) constituting the textured pattern to less than 500 μm, it is possible to suppress the penetration of glass fibers with a fiber length of 500 to 1000 μm, which are most abundant near the surface of the resin molded product, into the convex portion, and the occurrence of bright areas shown in Figure 9C can be particularly suppressed. Furthermore, the textured pattern according to the present invention exhibits similar effects and properties not only for fiber-reinforced materials but also for plate-shaped reinforcing materials such as talc and granular reinforcing materials such as glass beads. In other words, in resin molded products made of resin materials containing reinforcing materials such as plate-shaped reinforcing materials and granular reinforcing materials, it is possible to suppress the uneven distribution of reinforcing materials near the surface and the occurrence of bright areas on the surface.

[0054] [Embodiment of the Invention] According to this embodiment, a resin molded product is provided, comprising a resin material containing a resin and a fiber reinforcing material, wherein the proportion of the fiber reinforcing material having a length greater than 0 and less than 3000 μm is 10 to 100%, and a textured pattern including a plurality of first protrusions is provided on at least a part of the surface, and the maximum length of the first base of the first protrusions is greater than 0 and less than Lcos(20°) μm, where L is the average fiber length of the fiber reinforcing material. This makes it possible to suppress uneven coloration of the surface of the resin molded product due to resin reinforcing materials such as glass fibers.

[0055] In the resin molded product of this embodiment, the maximum length of the first base portion is greater than 0 and less than 2000 μm. This further suppresses the uneven coloration of the surface of the resin molded product caused by the resin reinforcing material.

[0056] In the resin molded product of this embodiment, the maximum length of the first base portion is greater than 0 and less than 500 μm. This further suppresses the uneven coloration of the surface of the resin molded product caused by the resin reinforcing material.

[0057] In the resin molded product of this embodiment, the maximum height of the first protrusion with respect to the first base is greater than 0, and less than Lcos(20°)tan(20°) when the average fiber length is L. This further suppresses the uneven coloration of the surface of the resin molded product due to the resin reinforcing material.

[0058] In the resin molded product of this embodiment, the textured pattern includes a plurality of first protrusions and a plurality of second protrusions, the maximum length of the second base of the second protrusion is Lcos(20°) μm or more when the average fiber length is L, and the first protrusions are formed on the surface of the second protrusions. As a result, resin molded products can be manufactured by modifying conventional molds, thus reducing the labor required to manufacture molds.

[0059] In the resin molded product of this embodiment, the maximum height of the first protrusion with respect to the first base is 10 to 100% of the maximum height of the second protrusion with respect to the second base. This allows the resin molded product to be smoothly released from the mold.

[0060] In the resin molded product of this embodiment, if the first protrusion is formed on an inclined surface that forms a less than predetermined angle with respect to the depth direction of the resin molded product, the maximum height of the first protrusion provided on the inclined surface, with the first base as the reference position, is lower than the maximum height of the first protrusion provided on a surface other than the inclined surface, with the first base as the reference position. This allows the resin molded product to be smoothly released from the mold.

[0061] In the resin molded product of this embodiment, at least one of a third protrusion and a recess is formed between adjacent second protrusions, the maximum length of the third base of the third protrusion is greater than 0 and less than Lcos(20°) μm when the average fiber length is L, and the maximum length of the bottom surface of the recess facing the opening is greater than 0 and less than Lcos(20°) μm when the average fiber length is L. This further suppresses the uneven coloration of the surface of the resin molded product due to the resin reinforcing material.

[0062] Furthermore, according to this embodiment, a resin molded product is provided which is made of a resin material containing a resin and a fiber reinforcing material, wherein the proportion of the fiber reinforcing material having a length greater than 0 and less than 3000 μm is 10 to 100%, a textured pattern consisting of a plurality of protrusions is applied to at least a part of the surface, the maximum length of the base of the protrusions is 2000 μm or more, and recesses are formed in the protrusions, the maximum length of the bottom surface facing the opening is greater than 0 and less than 2000 μm. This makes it possible to suppress uneven coloration of the surface of the resin molded product due to resin reinforcing materials such as glass fibers.

[0063] In the resin molded product of this embodiment, the maximum depth of the recess with respect to the opening is 10 to 100% of the maximum height of the protrusion with respect to the base. This allows the resin molded product to be smoothly released from the mold.

[0064] In the resin molded product of this embodiment, if the protrusion is formed on an inclined surface that forms a less than predetermined angle with respect to the depth direction of the resin molded product, the maximum depth of the recess of the protrusion provided on the inclined surface, with respect to the opening, is smaller than the maximum depth of the recess of the protrusion provided on a surface other than the inclined surface, with respect to the opening. This allows the resin molded product to be smoothly released from the mold.

[0065] In the resin molded product of this embodiment, at least one of a protrusion different from the protrusion and a recess different from the recess are formed between adjacent protrusions, the maximum length of the base of the different protrusion is greater than 0 and less than 2000 μm, and the maximum length of the bottom surface of the different recess facing the opening is greater than 0 and less than 2000 μm. This makes it possible to further suppress the uneven color of the surface of the resin molded product caused by the resin reinforcing material.

[0066] 10, 10x... Resin molded product 10a... Inclined surface 11, 13... First convex part 12... Second convex part 11a, 13a... First base part 12a... Second base part 14, 16... Recessed part 15, 17, 10y... Convex part 15a, 17a... Base part 14a, 16a... Opening 14b, 16b... Bottom surface 20... Molding mold 21... Fixed mold 22... Movable mold 30... Cavity 31... Gate A1... Dark area A2... Bright area D1, D2... Maximum depth GF... Glass fiber H1, H2, H3, H4, H5... Maximum height α... Lower angle

Claims

1. A resin molded product comprising a resin material containing a resin and a fiber reinforcing material, wherein the proportion of the fiber reinforcing material having a length greater than 0 and less than 3000 μm is 10 to 100%, and a textured pattern including a plurality of first protrusions is applied to at least a part of the surface, and the maximum length of the first base of the first protrusions is greater than 0 and less than Lcos(20°) μm, where L is the average fiber length of the fiber reinforcing material.

2. The resin molded article according to claim 1, wherein the maximum length of the first base is greater than 0 and less than 2000 μm.

3. The resin molded article according to claim 1 or 2, wherein the maximum length of the first base is greater than 0 and less than 500 μm.

4. The resin molded article according to any one of claims 1 to 3, wherein the maximum height of the first protrusion with respect to the first base is greater than 0, and less than Lcos(20°)tan(20°) when the average fiber length is L.

5. The resin molded article according to any one of claims 1 to 4, wherein the textured pattern includes a plurality of first protrusions and a plurality of second protrusions, the maximum length of the second base of the second protrusions is Lcos(20°) μm or more when the average fiber length is L, and the first protrusions are formed on the surface of the second protrusions.

6. The resin molded article according to claim 5, wherein the maximum height of the first protrusion with respect to the first base is 10 to 100% of the maximum height of the second protrusion with respect to the second base.

7. The resin molded product according to any one of claims 1 to 6, wherein the first protrusion is formed on an inclined surface that forms a less than predetermined angle with respect to the depth direction of the resin molded product, and the maximum height of the first protrusion provided on the inclined surface with respect to the first base is lower than the maximum height of the first protrusion provided on a surface other than the inclined surface with respect to the first base.

8. A resin molded article according to claim 5 or 6, wherein at least one of a third protrusion and a recess is formed between adjacent second protrusions, the maximum length of the third base of the third protrusion is greater than 0 and less than Lcos(20°)μm when the average fiber length is L, and the maximum length of the bottom surface of the recess facing the opening is greater than 0 and less than Lcos(20°)μm when the average fiber length is L.

9. A resin molded product comprising a resin material containing a resin and a fiber reinforcing material, wherein the proportion of the fiber reinforcing material having a length greater than 0 and less than 3000 μm is 10 to 100%, a textured pattern consisting of a plurality of protrusions is applied to at least a part of the surface, the maximum length of the base of the protrusions is 2000 μm or more, and recesses are formed in the protrusions, the maximum length of the bottom surface opposite the opening is greater than 0 and less than 2000 μm.

10. The resin molded article according to claim 9, wherein the maximum depth of the recess with respect to the opening is 10 to 100% of the maximum height of the protrusion with respect to the base.

11. If the protrusion is formed on an inclined surface that forms a sub-angle of less than a predetermined angle with respect to the depth direction of the resin molded product, the maximum depth of the recess of the protrusion provided on the inclined surface, with respect to the opening, is smaller than the maximum depth of the recess of the protrusion provided on a surface other than the inclined surface, with respect to the opening.

12. A resin molded article according to any one of claims 9 to 11, wherein at least one of a protrusion different from the protrusion and a recess different from the recess are formed between adjacent protrusions, the maximum length of the base of the different protrusion is greater than 0 and less than 2000 μm, and the maximum length of the bottom surface of the different recess facing the opening is greater than 0 and less than 2000 μm.

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