Resin member, mold for molding resin member, and method for manufacturing resin member

Abstract

To provide a resin member that has a high designability and high scratch resistance in a combination manner.SOLUTION: There is provided a resin member having a resin base material and a fine uneven shape consisting of a plurality of mountain-shapes and a plurality of valley-shapes. In any cross section of the fine uneven shape, mountain peaks for calculation include a plurality of first mountain peaks having a cross-sectional height of 15 μm or more and less than 30 μm, and a plurality of second mountain peaks having a cross-sectional height of 8 μm or more and less than 15 μm; and a presence ratio of the second mountain peaks to the first mountain peaks per unit length of the cross section is 50% or more and 100% or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a resin member, a mold for molding the resin member, and a method for manufacturing the resin member. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a fine uneven pattern has been formed on the surface of a resin member to improve the design of the appearance (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a resin member having a fine uneven pattern on its surface. The fine uneven pattern has a first convex portion and a second convex portion that is shorter in height than the first convex portion. The pitch between the convex portions is set within a predetermined range, thereby reducing the proportion of inclined surfaces formed, for example, at the transition portions from the concave portions to the convex portions of the fine uneven pattern. This increases the gloss and shading of the surface, improving the design of the appearance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-82498 A Summary of the Invention [Problem to be solved by the invention]

[0005] Although the resin part of Patent Document 1 can increase the surface gloss and shading, there is still room for improvement in terms of achieving both a sense of shading and a grainy feel (surface texture) in terms of design.

[0006] Specifically, there is a problem that it is difficult to ensure a sufficient sense of shading if the fine uneven shape (for example, a grain pattern) is made too fine. In particular, in the resin member of Patent Document 1, the number of second convex portions is greater than the number of first convex portions, and the fine uneven shape tends to be whitish overall and lack a sense of shading.

[0007] On the other hand, if too much emphasis is placed on the sense of shadow, and the fine unevenness is made coarse, it becomes difficult to ensure a sufficient graininess (surface texture). In addition, while it is possible to enhance the sense of shadow by adjusting the angle of the transition between the peak and bottom of the fine unevenness, there is a problem that fine adjustment of the angle is difficult to control in manufacturing.

[0008] Furthermore, it is important for resin components to have sufficient scratch resistance as well as high designability. In conventional resin components, if scratch resistance is insufficient due to prioritizing either design or appearance, a coating process is required to ensure scratch resistance, which increases the number of manufacturing steps and costs, and is also undesirable from an environmental standpoint.

[0009] Therefore, an object of the present disclosure is to provide a resin component that has excellent graininess and shading while also allowing the omission of a surface painting process, and that combines high designability and high scratch resistance, a mold for molding the resin component, and a method for manufacturing the resin component. [Means for solving the problem]

[0010] In order to solve the above problems, the resin member disclosed herein comprises: A resin member including a resin base material and a fine uneven shape formed on a surface of the resin base material and consisting of a plurality of peaks and a plurality of valleys, In any cross section of the fine unevenness, the height of the reference line at an average height obtained by averaging the heights of the three deepest valley bottom points included in the fine concave-convex shape is set to zero, and the shortest distance from the reference line to any point on the fine concave-convex shape is defined as a cross-sectional height; When a peak having a difference of 2.0 μm or more between the cross-sectional height of an arbitrary peak of the fine uneven shape and the cross-sectional heights of two valley bottom points adjacent to the peak is set as a peak for calculation, The calculation peak is A plurality of first apexes each having a cross-sectional height of 15 μm or more and less than 30 μm; a plurality of second apexes each having a cross-sectional height of 8 μm or more and less than 15 μm; The ratio of the second peaks to the first peaks per reference length of the cross section is 50% or more and 100% or less. It is characterized by:

[0011] The resin member of this configuration has a fine uneven shape with the above-mentioned first and second peaks having different cross-sectional heights in the above-mentioned ratio. This can enhance the graininess and the sense of shadow. When a contact such as a nail comes into contact with the surface of the resin member, the first convex portion, which is a mountain including the first peak having a relatively high cross-sectional height, is deformed by the load input from the contact. On the other hand, the contact of the contact is suppressed with the second convex portion, which is a mountain including the second peak having a smaller cross-sectional height than the first peak, and the deformation of the second convex portion is suppressed. Thus, scratches become intermittent and are less noticeable in appearance, and the scratch resistance of the resin member can be improved. Furthermore, even if scratches are formed on the surface of the first convex portion, scratches are not formed on the second convex portion, so that the second convex portion can maintain an excellent graininess and can suppress excessive deterioration of the design at the scratched portion and its surrounding area. In this way, a resin member having both high designability and high scratch resistance can be obtained.

[0012] The cross section may be, for example, any cross section perpendicular to the reference surface (ISO 25178) of the fine concave-convex shape.

[0013] In this specification, a "peak" is a point having a cross-sectional height higher than the cross-sectional height of an adjacent point on the fine unevenness in the cross-section, and a "valley point" is a point having a cross-sectional height lower than the cross-sectional height of an adjacent point on the fine unevenness in the cross-section.

[0014] Preferably, with respect to the Y value, which is the reflectance of light incident on the surface at an incident angle of 45°, the Y value at a light-receiving angle of 45° is 100 or more, and the Y value at a light-receiving angle of 60° is 70 or less.

[0015] According to this configuration, the maximum value of the Y value, which is the reflectance, is large and the peak width is small, so that the sense of shadow is improved.

[0016] Preferably, an average value of a distance between two adjacent first peaks in the reference line direction per reference length is not less than 200 μm and not more than 800 μm.

[0017] According to this configuration, the light is reflected by the peaks of the ridges, improving the sense of shadow. Also, the input load from the contact can be effectively dispersed by the first protrusions, improving scratch resistance.

[0018] Preferably, an average value of a distance between two adjacent second peaks in the reference line direction per reference length is not less than 200 μm and not more than 2000 μm.

[0019] According to this configuration, since the second convex portions are appropriately present between the first convex portions, the increase in the contrast difference between the scratched portion and its surrounding area caused by continuous deformation of the first convex portions is suppressed, thereby improving scratch resistance.

[0020] Preferably, the average value of the distance between two adjacent calculation mountain apexes in the reference line direction per reference length is not less than 200 μm and not more than 400 μm.

[0021] According to this configuration, the graininess is improved by the moderate presence of the calculation convex portion, which is a mountain including the calculation mountain apex.

[0022] Preferably, the cross section is a cross section obtained by measuring an arbitrary rectangular field of the surface with a laser microscope; The rectangular field of view is 18000 μm by 18000 μm; The scanning resolution of the laser microscope is 0.1 μm; The reference length is 18000 μm, The cross-sectional height of any point of the fine unevenness in the cross-section is a value obtained by averaging the cross-sectional height values ​​of actual measurement points measured at a distance of 1.4 μm in the reference line direction at every 71 μm.

[0023] This configuration is advantageous in providing a resin component that combines high design quality and high scratch resistance.

[0024] The molding die disclosed herein is a molding die for producing the above-mentioned resin member.

[0025] According to the present technology, it is possible to provide a resin component that combines excellent design and high scratch resistance.

[0026] The method for producing a resin part disclosed herein is characterized in that the resin part is produced by injection molding using the above-mentioned molding die.

[0027] According to the present technology, it is possible to provide a resin component that combines excellent design and high scratch resistance. Effect of the Invention

[0028] As described above, according to the present disclosure, it is possible to provide a resin component that combines high designability with high scratch resistance. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a diagram showing a resin member according to an embodiment. [Diagram 2] 2 is a schematic perspective view showing an enlarged view of a portion near a surface of the resin member shown in FIG. 1. [Diagram 3] 3 is a diagram showing a simplified schematic view of a part of a cross section perpendicular to a plane P of a surface of the resin member in FIG. 2. FIG. [Figure 4] FIG. 2 is a diagram for explaining a method for measuring reflectance (Y value). [Diagram 5] 4 is a flowchart for explaining a method for manufacturing a resin member according to an embodiment. [Figure 6] 1A and 1B are schematic front and side views of resin test pieces of Examples and Comparative Examples. [Figure 7]FIG. 2 is a diagram showing a cross-sectional profile of the fine concave-convex shape of the resin test piece in Example 1 and a shape profile of a mold for producing the resin test piece. [Figure 8] FIG. 8 is a partially enlarged view of the cross-sectional profile of FIG. [Figure 9] FIG. 4 is a partially enlarged view of the cross-sectional profile of the fine concave-convex shape of the resin test piece of Example 2. [Figure 10] 1 is a graph showing the results of optical measurements in an example and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0031] (Embodiment 1) <Resin parts> 1 shows an example of a resin member 1 according to this embodiment. The resin member 1 is, for example, a fender for an automobile C. The resin member 1 is not limited to automobile fenders, and is suitable for, for example, engine covers, bonnets, roofs, doors, front panels, side panels, rear panels, front bodies, lift gates, various members, various frames, bumpers, under covers, instrument panels, seat frames, door trims, pillar trims, and other vehicle parts for automobiles, motorcycles, and the like, landing gear pods, winglets, spoilers, edges, ladders, elevators, failings, ribs, and other aircraft parts, and electrical and electronic device parts such as housings for personal computers, mobile phones, tablets, audio equipment, air conditioners, and lighting equipment.

[0032] Fig. 2 is an enlarged schematic view of a portion of the surface of the fender in Fig. 1. As shown in Fig. 2, the resin member 1 according to this embodiment includes a resin base material 2 and a fine concave-convex pattern 3 formed on the surface of the resin base material 2.

[0033] Since the resin member 1 according to the present embodiment has excellent scratch resistance, painting can be omitted, but painting may still be performed. From the viewpoint of improving design and scratch resistance, various painting processes may be performed by a conventionally known method as necessary.

[0034] <Resin substrate> The resin base material 2 serves to form the skeleton of the resin member 1 .

[0035] The resin material of the resin base material 2 is not particularly limited, but may be, for example, a thermoplastic resin material, a thermosetting resin material, or a mixture thereof, as exemplified below.

[0036] Specific examples of thermoplastic resin materials include polypropylene resin, polyethylene resin, polycarbonate resin, polyamide resin, polyester resin, polyarylene sulfide resin, polyphenylene sulfide resin, polyether ketone, polyether ether ketone resin, polyether ketone ketone resin, polyether sulfone resin, polyimide resin, polyamide imide resin, polyether imide resin, polysulfone resin, and the like.

[0037] Specific examples of thermosetting resin materials include epoxy resin, vinyl ester resin, phenol resin, polyimide resin, polyurethane resin, urea resin, melamine resin, bismaleimide resin, unsaturated polyester resin, and urethane acrylate resin.

[0038] These thermoplastic resin materials and / or thermosetting resin materials can be used alone, or as a copolymer of one type of resin material with another resin material, a modified product, a resin material in which two or more types are blended, etc. When a mixture of a thermoplastic resin material and a thermosetting resin material is used as the resin material, the compounding ratio thereof can be appropriately determined depending on the type of resin material, moldability, strength of the resin member 1, etc.

[0039] In order to color the resin member 1, a coloring material such as a pigment, a dye, or a coloring masterbatch may be added to the resin material. From the viewpoint of improving the moldability, strength, design, functionality, and the like of the resin member 1, the resin material may further contain additives such as reinforcing fibers such as carbon fiber, glass fiber, or basalt fiber, fillers such as talc, impact modifiers, UV absorbers, or functional masterbatches. These coloring materials and additives may be added alone or in combination.

[0040] When a coloring material is contained in the resin part 1, the amount of the coloring material can be, for example, 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the resin material consisting of a thermosetting resin material and a thermoplastic resin material, from the viewpoint of obtaining excellent design while ensuring sufficient moldability and strength.

[0041] When additives, etc. are contained in the resin part 1, from the viewpoint of improving moldability, strength, design, functionality, etc., the content of the additives can be, for example, 40 volume % or more and 70 volume % or less if the additives are reinforcing fibers, and can be, for example, 5 mass % or less if the additives are other than reinforcing fibers.

[0042] ≪Minute uneven shape≫ As shown in FIG. 2, the fine unevenness 3 formed on the surface of the resin base material 2 is intended mainly to enhance the design of the resin member 1, and is made up of a plurality of peaks 3A and a plurality of valleys 3B.

[0043] Fig. 3 is a simplified schematic diagram of a part of a cross section perpendicular to the plane P of the surface of the resin member 1 in Fig. 2. The cross-sectional shape of the fine unevenness 3 can be observed, for example, by measuring an arbitrary rectangular field of view on the surface of the resin base material 2 with a laser microscope, an optical microscope, or the like.

[0044] -Cross-sectional height of fine uneven shape- When the fine concave-convex shape 3 is observed with a laser microscope, for example, as shown in Fig. 2, a plane P passing through the deepest valley bottom point 33d within a rectangular field of view is defined. The plane P is, for example, a plane that passes through the valley bottom point 33d and is parallel to a reference surface (ISO 25178).

[0045] 3, a reference line L is set at an average height obtained by averaging the heights from plane P of the three deepest valley bottom points 33a, 33b, and 33c included in the fine uneven shape 3. The reference line L is a straight line parallel to plane P. In this specification, the cross-sectional height H is defined as the shortest distance from the reference line L to any point on the fine uneven shape 3 when the height of the reference line L is set to zero.

[0046] - Calculation of the peak of fine unevenness - In the cross section of FIG. 3, any peak apex of the fine unevenness 3 where the difference between the cross-sectional height of the peak and the cross-sectional heights of the two valley bottom points adjacent to the peak apex is 2.0 μm or more is defined as a peak apex for calculation 30a.

[0047] At this time, the calculation mountain vertex 30a includes a first mountain vertex 31a and a second mountain vertex 32a.

[0048] The first peak 31a has a cross-sectional height H1 of 15 μm below the threshold H T The thickness is 15 μm or more and less than 30 μm, preferably 16 μm or more and less than 29 μm.

[0049] The second peak 32a has a cross-sectional height H2 of 8 μm or more and less than 15 μm, preferably 8.2 μm or more and less than 14.9 μm.

[0050] In this specification, the ratio of second peaks 32a to first peaks 31a per reference length of the cross section is 50% or more and 100% or less, and preferably 50% or more and 89% or less.

[0051] The resin member 1 of this configuration can effectively enhance the graininess and shadow feel by having the fine uneven shape 3 have the first mountain apex 31a and the second mountain apex 32a with different cross-sectional heights H described above in the above-mentioned proportions.

[0052] As shown in FIG. 3, when a contact 51 such as a claw comes into contact with the surface of the resin member 1, the mountain including the first mountain apex 31a having a relatively high cross-sectional height H, i.e., the first convex portion 31, is deformed by the load input from the contact 51. On the other hand, the contact 51 is suppressed from coming into contact with the mountain including the second mountain apex 32a having a smaller cross-sectional height H than the first mountain apex 31a, i.e., the second convex portion 32, and deformation of the second convex portion 32 is suppressed. Thus, scratches become intermittent and less noticeable in appearance, improving the scratch resistance of the resin member 1. Furthermore, even if scratches are formed on the surface of the first convex portion 31, scratches are not formed on the second convex portion 32, so that the second convex portion 32 can maintain an excellent graininess and suppress excessive deterioration of the design at the scratched portion.

[0053] In this way, the resin member 1 can have both high design quality and high scratch resistance.

[0054] If the cross-sectional height H1 of the first apex 31a is less than the above-mentioned lower limit, the difference with the cross-sectional height H2 of the second apex 32a will be too small, which may result in a decrease in the sense of shadow and scratch resistance. On the other hand, if the cross-sectional height H1 of the first apex 31a exceeds the above-mentioned upper limit, the fine uneven shape may become too coarse, which may result in a decrease in the graininess.

[0055] If the cross-sectional height H2 of the second peak 32a is less than the lower limit described above, the second protrusion 32 may become too small, resulting in a decrease in graininess. On the other hand, if the cross-sectional height H2 of the second peak 32a exceeds the upper limit described above, the contact may easily reach the second protrusion 32, resulting in a decrease in scratch resistance.

[0056] Furthermore, if the ratio of the second vertices 32a to the first vertices 31a is less than the lower limit, there will be fewer ridges between the first convex portions 31 that cause changes in light reflection, which may reduce the graininess. On the other hand, if the ratio exceeds the upper limit, the fine uneven shape 3 will be too fine, resulting in an overall white and blurred impression, which may reduce the sense of shadow.

[0057] -Pitch between the apexes of the mountains for calculation- The distance between two adjacent first apexes 31a, 31a in the direction of the reference line L, i.e., the average value per reference length of the pitch D1 of the first apexes 31a, is preferably 200 μm or more and 800 μm or less, and more preferably 400 μm or more and 700 μm or less.

[0058] According to this configuration, since light is reflected at the first peak 31a, the presence of the first convex portions 31 at the above pitch D1 ensures a sufficient amount of light in the highlighted portion, which contributes to improving the sense of shadow. Also, the presence of the first convex portions 31 at the above pitch D1 allows the input load from the contact 51 to be effectively dispersed by the first convex portions 31, improving scratch resistance.

[0059] In this specification, the reference length is the length of the measurement area in the cross section in the reference line L direction, and when the rectangular field of view is 18000 μm × 18000 μm, the reference length can be, for example, 18000 μm.) The distance in the reference line direction L between two adjacent second apexes 32a, 32a, i.e., the average value per reference length of the pitch D2 of the second apexes 32a, is preferably 200 μm or more and 2000 μm or less, more preferably 400 μm or more and 1000 μm or less, and particularly preferably 600 μm or more and 900 μm or less.

[0060] According to this configuration, since the second convex portions 32 are appropriately present between the first convex portions 31, it is possible to suppress an increase in the contrast difference between a scratched portion and its surrounding area caused by continuous deformation of the first convex portions 31, thereby improving scratch resistance. Even if a scratched portion is formed, the second convex portions 32 allow an excellent graininess to be maintained.

[0061] The distance between two adjacent calculation mountain apexes 30a in the direction of the reference line L, i.e., the average value per reference length of the pitch D of the calculation mountain apexes 30a, is preferably 200 μm or more and 400 μm or less, and more preferably 250 μm or more and 350 μm or less.

[0062] According to this configuration, the presence of the calculation convex portion 30, which is a mountain including an appropriate calculation mountain apex 30a, effectively improves the graininess, the sense of shadow, and the scratch resistance.

[0063] Although not intended to be limiting, the proportion of calculation apexes 30a among the apexes included per reference length can be, for example, 65% or more and 98% or less, preferably 71% or more and 95% or less, more preferably 72% or more and 94% or less, and may be 75% or more and 94% or less.

[0064] -Optical properties of resin components (Y value)- The sense of shadow on the surface of the resin member 1 having the fine unevenness 3 can be evaluated by irradiating light at a specific angle of incidence onto the surface and measuring the reflectance of the light reflected from the surface. When measuring optical characteristics, the surface is considered to be a flat surface such as a reference surface (ISO 25178).

[0065] The reflectance of reflected light is also called luminous reflectance and is expressed as the Y value in the XYZ color system of CIE 1931. Figure 4 shows an outline of the method for measuring the Y value.

[0066] 4, assuming that the normal to the measurement target point on the surface having the fine unevenness 3 is N, incident light 120 is incident from light source 200 at an incident angle α with respect to the normal N. Then, reflected light 130 reflected from the surface is detected by light receiver 300 disposed at a position with a light-receiving angle γ. The light-receiving angle γ of light receiver 300 is the angle of light receiver 300 with respect to the normal N.

[0067] The Y value can be measured, for example, by using a commercially available goniospectrophotometer. The goniospectrophotometer can automatically change the angles of the light source 200 and the light receiver 300, thereby arbitrarily setting the incident angle α of the incident light 120 and the receiving angle γ of the reflected light 130.

[0068] For example, if the incident angle α is 45°, the shadow effect is calculated by the reflectance Y of the regular reflected light with a light receiving angle γ of 45°. 45° and the reflectance Y of the reflected light with a receiving angle γ of 60° 60° It can be evaluated by the size of

[0069] In detail, the reflectance of specular light Y 45° The value of Y contributes to the highlights of the reflected light, so the larger this value is, the stronger the sense of gloss will be when the specular light enters the observer's field of vision. 60° The smaller the value of Y, the narrower the width of the reflectance peak that contributes to the highlights. In other words, while the specular reflected light gives a strong sense of gloss, even a slight change in the receiving angle (15° in this case) greatly reduces the amount of reflected light, so the observer feels a distinct sense of shadow. 45° The value of Y is large. 60° The smaller the value, the better the sense of shadow.

[0070] Y of reflected light from resin part 1 45° The value of Y of the reflected light of the resin member 1 is preferably 100 or more, and more preferably 110 or more and 200 or less. 60° The value of Y is preferably 70 or less, and more preferably 10 or more and 60 or less. 45°If the value is less than the lower limit, sufficient gloss may not be obtained, and the sense of shadow may be reduced. 60° If the value of Y exceeds the upper limit, the range of light-receiving angles that give gloss will be wider, resulting in an overall white and blurred impression and a reduced sense of shadow. 45° The value of Y 60° When the value of satisfies the above range, the sense of shadow is improved.

[0071] <Method of manufacturing resin components> The resin member 1 according to this embodiment is manufactured by injection molding using a molding die 5 as shown in the upper diagram of FIG.

[0072] 5, the method for producing the resin member 1 includes a mold preparation step S1, a first etching step S2, a second etching step S3, an optional blasting step S4, an optional polishing step S5, and a molding step S6. Each step will be described below.

[0073] <Mold preparation process S1> The molding die 5 includes a die base material 6 and an inverted shape 7 formed on the surface thereof. In the die preparation step S1, the die base material 6 is prepared.

[0074] The die substrate 6 of the molding die 5 can be any metal material used in general injection molding dies for resin materials, specifically, for example, steel, zinc alloy, aluminum alloy, etc. These metal materials are cut to obtain the die substrate 6 for molding the desired shape of the resin member 1.

[0075] <First etching process S2> An inverted shape 7 for forming the fine uneven shape 3 of the resin member 1 is formed on the molding surface of the mold substrate 6 by the first etching step S2, the second etching step S3, and the blasting step S4. The inverted shape 7 is an inverted uneven shape of the fine uneven shape 3, and is transferred to the surface of the resin member 1 by the subsequent molding step S6.

[0076] The first etching step S2 is a step for forming a rough uneven shape on the molding surface of the molding die 5 as a preparatory step for forming the inverted shape 7. The first etching step S2 is performed by treating the molding surface of the molding die 5 with an etching solution, and then washing the die substrate 6 with water or the like. As the etching solution, for example, a chemical polishing solution for steel or a ferric perchloride solution is used alone, or a mixture of water, nitric acid, hydrochloric acid, or the like is used. The ingredients and the mixing ratio of the etching solution and the etching treatment time are appropriately determined depending on the material of the die substrate 6 to be etched, the desired height H of the fine uneven shape 3, the desired pitch D, and the like.

[0077] <<Second etching process S3>> The second etching step S3 is a step for forming a finer uneven shape by further etching the molding surface on which the rough uneven shape was formed in the first etching step S2. The procedure of the second etching step S3 is the same as that of the first etching step S2, and is performed by treating the molding surface with an etching solution and then washing the mold with water or the like. The etching solution can be the same as that of the first etching step S2, and may be the same etching solution as that of the first etching step S2 or a different etching solution. When the same etching solution is used, it may have the same blending ratio or may have a different blending ratio. The blending components and blending ratio of the etching solution and the etching treatment time are appropriately determined according to the material of the mold substrate 6 to be etched, the desired cross-sectional height of the fine uneven shape 3, the desired pitch, etc., as in the first etching step S2.

[0078] <Blasting process S4> The blasting step S4 is a step in which a blasting treatment is performed on the molding surface of the mold substrate 6 after the second etching step S3 to obtain an inverted shape 7. When the inverted shape 7 is transferred to the surface of the resin substrate 2, a fine uneven shape 3 is formed. Examples of the blasting treatment include bead blasting and sand blasting, but from the viewpoint of obtaining an inverted shape 7 that provides the desired fine uneven shape 3, it is preferable to employ a bead blasting treatment using glass beads having an average particle size D50 of about 50 μm to 300 μm. Note that this blasting step S4 is an optional step and can be provided as necessary.

[0079] ≪Polishing process S5≫ The polishing step S5 is a step of polishing the molding surface of the mold substrate 6 having the inverted shape 7 formed thereon, thereby reducing the minute unevenness even more than that of the inverted shape 7. Specifically, the molding surface is polished with an abrasive such as a buff cloth. By appropriately adjusting the etching conditions in the first etching step S2 and the second etching step S3 and the blasting conditions in the blasting step S4, and by providing the polishing step S5, the minute unevenness formed on the surface of the inverted shape 7 is scraped off, the surface of the inverted shape 7 becomes smooth, and the surface roughness is reduced. In this way, the final molding die is obtained. Note that this polishing step S5 is an optional step and can be provided as necessary.

[0080] ≪Molding process S6≫ The molding die 5 is set in an injection molding device equipped with a fixed die and a movable die, and a resin material is injected into a cavity formed by a molding surface to perform molding. The injection molding conditions may be general conditions used in injection molding of resin materials, and may be appropriately changed depending on the resin material. After the resin material injected into the cavity solidifies, the molding die is released to obtain the resin member 1.

[0081] (Other embodiments) In the above embodiment, the resin member 1 is manufactured by injection molding, but the manufacturing method of the resin member 1 is not limited to injection molding, and may be, for example, extrusion molding, vacuum molding, blow molding, injection compression molding, decorative molding, gas-assisted injection molding, foam injection molding, low-pressure molding, ultra-thin injection molding (ultra-high speed injection molding), in-mold composite molding (insert molding, outsert molding), or a method of molding a precursor sheet obtained by laminating sheets of a resin material by press molding, etc. From the viewpoints of production stability, economy, etc., injection molding, injection compression molding, and molding methods that combine these with in-mold composite molding are preferable.

[0082] When forming a fine uneven shape on part of the surface of the resin component 1, this can be achieved by forming, for example, a corrosion-resistant coating on the molding surface of the molding die in areas where the formation of a fine uneven shape is not desired. EXAMPLES

[0083] Next, specific examples will be described.

[0084] (Resin test piece) <Example 1> <Mold manufacturing> As shown in Fig. 6, a molding die 5 was prepared for manufacturing a resin test piece 11 having a length (w1) of 100 mm × width (w2) of 80 mm × thickness (t) of 3.0 mm by injection molding as the resin member 1. Note that a fine uneven shape 3 is formed on the front surface indicated by reference numeral 12, and the fine uneven shape 3 is not formed on the back surface 13.

[0085] A commercially available steel material was cut as the mold substrate 6. A corrosion-resistant coating or the like was formed on the molding surface of the mold substrate 6 at a location where the formation of the inverted shape 7 was not desired. The molding surface was then immersed in an acidic etching solution in the air at room temperature to perform a first etching treatment to a depth of 30 μm. The mold substrate 6 was then washed with water. Thereafter, the mold substrate 6 was further immersed in the above mixed solution to perform a second etching treatment to a depth of 10 μm. The mold substrate 6 was then washed with water. The molding surface was then subjected to a bead blasting treatment using glass beads of a specified size. Thus, a molding die 5 having an inverted shape 7 formed on the molding surface was obtained.

[0086] <Production of resin test pieces> As the resin material, 98 parts by mass of polypropylene resin (manufactured by Japan Polypropylene Corporation) and 2 parts by mass of a colored master batch (manufactured by DIC Corporation) were used, and molding was performed using a 180-ton injection molding machine (manufactured by Fanuc Corporation) equipped with the above-mentioned molding die 5, to obtain a resin test piece 11.

[0087] <Examples 2 to 5> Resin test pieces of Examples 2 to 5 were obtained in the same manner as in Example 1, except that a corrosion-resistant coating or the like was formed on the molding surface of mold substrate 6 at locations different from those in Example 1.

[0088] <Comparative Example 1> A corrosion-resistant coating or the like was formed on the molding surface of the mold substrate 6 in a different location from that in Example 1, and a resin test piece was obtained in the same manner as in Example 1, except that the first etching treatment was performed to a depth of 15 μm and the second etching treatment was performed to a depth of 15 μm.

[0089] <Comparative Example 2> A corrosion-resistant coating or the like was formed on the molding surface of the mold substrate 6 in a different location from that in Example 1, and a resin test piece was obtained in the same manner as in Example 1, except that the first etching treatment was performed to a depth of 30 μm, the second etching treatment was performed to a depth of 10 μm, and a third etching treatment was performed to a depth of 10 μm.

[0090] <Comparative Example 3> A corrosion-resistant coating or the like was formed on the molding surface of the mold substrate 6 in a different location from that in Example 1, and a resin test piece was obtained in the same manner as in Example 1, except that the first etching treatment time was set to a depth of 30 μm, the second etching treatment was set to a depth of 10 μm, and a third etching treatment was set to a depth of 10 μm.

[0091] (Various measurements on resin test pieces) Table 1 shows the results of various tests on the resin test pieces of Examples 1 to 5 and Comparative Examples 1 to 3.

[0092] [Table 1]

[0093] <Surface shape observation test> The fine unevenness formed on the surface of the resin test piece was observed using a hybrid laser microscope (OPTELICS HYBRID L7-GA300, manufactured by Lasertec Corporation, scan resolution: 0.1 μm).

[0094] The size of the rectangular visual field was 18000 μm×18000 μm, and the reference length was 18000 μm.

[0095] The reference line L was determined by the above-mentioned method, and the cross-sectional height H was calculated. The information used to determine the reference line L in Example 1 and Comparative Example 1 is shown in Table 2.

[0096] [Table 2]

[0097] The cross-sectional height of any point on the fine unevenness 3 in the cross section was determined by averaging the shortest distance from the reference line L of the actual measurement points measured every 1.4 μm in the direction of the reference line L every 71 μm in the direction of the reference line L.

[0098] 7 and 8 show cross-sectional profiles of the fine concave-convex shape 3 of the resin test piece of Example 1. Note that Fig. 8 is a graph showing an enlarged region of measurement positions 8000 µm to 13000 µm in Fig. 7.

[0099] FIG. 9 shows a partially enlarged view of the cross-sectional profile of the fine concave-convex shape 3 of the resin test piece of Comparative Example 1.

[0100] 8 and 9, the height of the calculation mountain apex 30a from the plane P is shown as a numerical value. In addition, in the figures, the reference line L and the threshold value H of the cross-sectional height H T is shown by a dashed line. Note that the reference line L and the threshold value H T The height from plane P is shown in parentheses.

[0101] - Regarding the cross-sectional height, pitch, and ratio of the second peak to the first peak - 8 and 9, for example, in the reference length of the cross-sectional profile of the fine uneven shape 3, the cross-sectional height H1 (μm) of the first peak apex 31a, the cross-sectional height H2 (μm) of the second peak apex 32a, the average value per reference length of the pitch D1 of the first peak apex 31a, the average value per reference length of the pitch D2 of the second peak apex 32a, and the average value per reference length of the pitch D (μm) of the calculation peak apex 30a were calculated based on the height from the plane P. The results are shown in Table 1.

[0102] <Optical property measurement test> The Y value was measured using a goniospectrophotometer (3D goniospectrophotometer GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd.). The incident angle α was set to 45°, and the receiving angle γ was set to -80° to 80° (in 5° increments). The measurement results are shown in FIG. 10 and Table 1.

[0103] In the resin test piece of Comparative Example 1, Y 45° The value of is high, but Y 60° The value of Y is also high, and the sense of shadow is poor. 45° The value of Y is too low. Compared with the test pieces of Comparative Examples 1 to 3, the resin test pieces of Examples 1 and 2 have 45° If the value of is high enough, 60°The value of is sufficiently low. In fact, as shown in Table 1, it is clear that the sense of shadow is excellent.

[0104] <Visual Observation Test> Three testers observed the surface of the resin test piece with their eyes 30 cm away from the surface. The evaluation items were (1) shadow effect and (2) graininess. For each of the evaluation items (1) and (2), each tester rated the surface on a five-point scale: 5...very good, 4...good, 3...average, 2...bad, 1...very bad. The observation results were then calculated from the average of all testers' evaluation results, with ◎ being greater than 4 and less than 5, ○ being greater than 3 and less than 4, △ being greater than 2 and less than 3, and × being less than 2.

[0105] As shown in Table 1, the resin test pieces of Comparative Examples 1 to 3 were all rated as x in two or more items. On the other hand, the resin test pieces of Examples 1 to 5 were found to be excellent in all of the shadow effect, graininess, and scratch resistance. [Industrial Applicability]

[0106] INDUSTRIAL APPLICABILITY The present disclosure is extremely useful since it can provide a resin member that combines high designability and high scratch resistance. [Explanation of symbols]

[0107] 1 Plastic parts 2. Resin substrate 3 Fine unevenness shape 3A Mountain 3B Valley 30 Convex part for calculation 30a Calculation mountain top 31 First protrusion 31a First Peak 32 Second protrusion 32a The second summit 33a, 33b, 33c, 33d Valley bottom point 5 Molding mold 51 Contact 6 Mold Base Material 7 Inverted Shape C car D Pitch of the apex of the calculated mountain D1 (first peak) pitch D2 (2nd peak) pitch H1 (First peak) section height H2 (2nd peak) section height P plane L reference line S1 Mold preparation process S2 First etching process S3 Second etching process S4 Blasting process S5 Polishing process S6 Molding process α angle of incidence γ acceptance angle

Claims

1. A resin member including a resin base material and a fine uneven shape formed on a surface of the resin base material and consisting of a plurality of peaks and a plurality of valleys, In any cross section of the fine unevenness, a cross-sectional height is defined as the shortest distance from a reference line to any point on the fine concave-convex shape when the height of the reference line at an average height obtained by averaging the heights of the three deepest valley bottom points included in the fine concave-convex shape is set to zero; When a peak having a difference of 2.0 μm or more between the cross-sectional height of an arbitrary peak of the fine uneven shape and the cross-sectional heights of two valley bottom points adjacent to the peak is set as a peak for calculation, The calculation peak is A plurality of first peaks each having a cross-sectional height of 15 μm or more and less than 30 μm; A plurality of second peaks each having a cross-sectional height of 8 μm or more and less than 15 μm, The ratio of the second peaks to the first peaks per reference length of the cross section is 50% or more and 100% or less. A resin member characterized by:

2. In claim 1, Regarding the Y value, which is the reflectance of light incident on the surface at an incident angle of 45°, the Y value at a light receiving angle of 45° is 100 or more, and the Y value at a light receiving angle of 60° is 70 or less. A resin member characterized by:

3. In claim 1 or 2, The average value of the distance between two adjacent first peaks in the reference line direction per reference length is 200 μm or more and 800 μm or less. A resin member characterized by:

4. In claim 1 or 2, The average value of the distance between two adjacent second peaks in the reference line direction per reference length is 200 μm or more and 2000 μm or less. A resin member characterized by:

5. In claim 1 or 2, The average value of the distance between two adjacent calculation mountain apexes in the reference line direction per reference length is 200 μm or more and 400 μm or less. A resin member characterized by:

6. In claim 1 or 2, the cross section is a cross section obtained by measuring an arbitrary rectangular field of view of the surface with a laser microscope; The rectangular field of view is 18000 μm×18000 μm; The scanning resolution of the laser microscope is 0.1 μm; The reference length is 18000 μm, The cross-sectional height of any point of the fine uneven shape in the cross section is a value obtained by averaging the cross-sectional height values ​​of actual measurement points measured at a distance of 1.4 μm in the reference line direction at the same distance of 71 μm. A resin member characterized by:

7. A molding die for producing the resin member according to claim 1.

8. The resin member is manufactured by injection molding using the molding die according to claim 6. A method for producing a resin member comprising the steps of:

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