Patterned object, injection molded object, and method of manufacturing an injection molded object

Abstract

A pattern forming object, an injection molded object, and a method of manufacturing an injection molded object, the method comprising: preparing a flat metal sheet; fixing the metal sheet to a mold for injection molding; clamping the mold; forming an injection molded object; and ejecting the injection molded object. The metal sheet has a first surface having a pattern formed thereon and a second surface opposite the first surface. The metal sheet is fixed to the mold with the first surface facing a cavity of the mold. The mold is clamped. Molten plastic is injected inside the cavity. The metal sheet is plastically deformed under the pressure of the molten plastic and the pattern formed on the first surface is transferred onto the product surface. After the molten plastic solidifies, the injection molded object is ejected from the mold with the metal sheet remaining in the mold.

Description

[0001] REFERENCE TO RELATED APPLICATION

[0002] This application claims priority to Japanese Patent Application No. 2023-126955 filed on August 3, 2023. The entire contents of the priority application are incorporated herein by reference. BACKGROUND

[0003] Generally, a mold surface molding sheet is known to be prepared by screen printing a plastic film on which a pattern including fine lines having a fine line pitch is formed, and the mold surface molding sheet is disposed inside a mold to transfer the pattern onto the surface of an injection-molded object. The mold surface molding sheet is thermally deformed along the inner surface of the mold by heat during injection molding and remains in the mold so that it adheres to the inner surface of the mold. At portions where the mold shape changes, for example, at the boundary between a cavity and a parting line, a deep crease is formed on the mold surface molding sheet. There is a problem that the mold surface molding sheet becomes fragile at the deep crease and can cause the mold surface molding sheet to break.

[0004] On the other hand, the inventors of the present disclosure invented a method of manufacturing an injection-molded object in which a mold surface molding sheet made of an elastomer having a pattern formed by protrusions and depressions is disposed inside a mold to transfer the pattern onto the surface of the injection-molded object. In this method, the mold surface molding sheet made of an elastomer has higher elasticity and is not easily damaged compared to a conventional plastic film. Therefore, durability is increased compared to a plastic film. SUMMARY

[0005] In the above-described mold surface molding sheet, repeated injection molding causes a deep crease to be formed in a component where the shape changes, such as at the boundary between a cavity and a parting line, which can cause the mold surface molding sheet to break. Therefore, it is desirable to improve the durability of the mold surface molding sheet.

[0006] Therefore, an object of the present disclosure is to increase the durability of a member for transferring a pattern to an injection-molded object.

[0007] A method for manufacturing an injection-molded object according to the present disclosure includes preparing a metal sheet, fixing the metal sheet to a mold for injection molding, clamping the mold, forming an injection-molded object, and discharging the injection-molded object.

[0008] In the step of preparing the metal sheet, a flat metal sheet is prepared. The metal sheet includes a first surface and a second surface opposite the first surface. A pattern is formed on the first surface by protrusions and depressions.

[0009] In the step of fixing the metal sheet, the metal sheet is fixed to a mold for injection molding. Specifically, the metal sheet is fixed to the mold with the first surface facing the cavity.

[0010] In the step of clamping the mold, the mold is clamped.

[0011] In the step of forming the injection-molded object, molten plastic is injected inside the cavity, a portion of the second surface is pressed against the inner surface of the mold, so that the metal sheet is plastically deformed by the pressure of the molten plastic. The pattern on the first surface is transferred to the product surface of the molten plastic by the pressure of the molten plastic.

[0012] In the step of discharging the injection-molded object, the injection-molded object is discharged from the mold with the metal sheet remaining inside the mold after the molten plastic is solidified.

[0013] Because the flat metal sheet is plastically deformed in the step of forming the injection-molded object, the metal sheet remains inside the mold with the metal sheet in close contact with the inner surface of the mold after the injection-molded object is discharged. After the injection-molded object is repeatedly manufactured, the metal sheet is not easily broken. Therefore, the durability of the member for transferring the pattern to the injection-molded object can be increased.

[0014] In the step of preparing the metal sheet, the pattern capable of being formed on the first surface can be formed by printing.

[0015] In the step of preparing the metal sheet, the metal sheet can be treated by flame treatment or primer treatment, and then the pattern can be formed on the first surface by printing.

[0016] Because the first surface of the metal sheet is surface-treated by the flame treatment or the primer treatment, the ink is less likely to be peeled off from the first surface, and thus the frequency of replacing the metal sheet can be reduced.

[0017] The metal sheet can be made of aluminum or an aluminum alloy.

[0018] In this case, the thickness of the metal sheet can be equal to or greater than 0.05 mm and equal to or less than 2 mm.

[0019] Because the thickness of the metal sheet made of aluminum or an aluminum alloy is equal to or greater than 0.05 mm and equal to or less than 2 mm, the metal sheet can be plastically deformed to be in close contact with the inner surface of the mold.

[0020] The metal sheet can be made of a steel plate.

[0021] In this case, the thickness of the metal sheet can be equal to or greater than 0.01 mm and equal to or less than 0.7 mm.

[0022] Because the metal sheet made of the steel sheet has a thickness equal to or greater than 0.01 mm and equal to or less than 0.07 mm, the metal sheet can be plastically deformed to be in close contact with the inner surface of the mold.

[0023] In another aspect, the present disclosure is a pattern forming object suitable for manufacturing in the above manufacturing method or suitable for use in the above manufacturing method.

[0024] The pattern forming object is an object on which an image as a pattern is formed, the image being a change image that changes depending on an observation angle.

[0025] The change image includes a first pattern, a second pattern, and a third pattern. The first pattern is composed of a plurality of line segments extending in a first direction. The second pattern is composed of a plurality of line segments extending in a second direction different from the first direction. The third pattern is composed of a plurality of line segments extending in a third direction different from the first direction and the second direction.

[0026] The first pattern is composed of a plurality of pattern units. Each pattern unit is composed of a pair of line segments having the same length. The pair of line segments are arranged side by side and positioned to be separated from each other by a distance d shorter than the length L of the line segment in a first width direction perpendicular to the first direction. The plurality of pattern units of the first pattern are arranged in the first direction, and the plurality of pattern units of the first pattern are arranged in the first width direction.

[0027] When one of two pattern units adjacent to each other in the first direction is designated as a first pattern unit and the other of the two pattern units is designated as a second pattern unit, the second pattern unit is positioned to be separated from the first pattern unit by a distance L1 shorter than the length L in the first direction, and the second pattern unit is offset from the first pattern unit by a distance d1 shorter than the distance d in the first width direction.

[0028] The second pattern can be composed of a plurality of pattern units. Each pattern unit can be composed of a pair of line segments having the same length. The pair of line segments can be arranged side by side and positioned to be separated from each other by the distance d in a second width direction perpendicular to the second direction. The plurality of pattern units of the second pattern can be arranged in the second direction, and the plurality of pattern units of the second pattern can be arranged in the second width direction. One of two pattern units adjacent to each other can be designated as a third pattern unit, and the other of the two pattern units can be designated as a fourth pattern unit. The fourth pattern unit can be positioned to be separated from the third pattern unit by the distance L1 in the second direction, and the fourth pattern unit can be offset from the third pattern unit by the distance d1 in the second width direction.

[0029] The pattern units forming the first pattern can be offset from each other by a distance L2 in the second direction. The pattern units forming the second pattern can be offset from each other by the distance L2 in the first direction. Two line segments of the pattern units forming the first pattern can be positioned to be spaced apart from each other by a distance D in the second direction. Two line segments of the pattern units forming the second pattern can be positioned to be spaced apart from each other by the distance D in the first direction. In a region in which the first pattern and the second pattern overlap, two line segments included in two adjacent pattern units of the first pattern adjacent to each other in the first width direction and two line segments included in two adjacent pattern units of the second pattern adjacent to each other in the second width direction can form a rhombus. Each side of the rhombus can have a length equal to the length L2. A plurality of rhombuses can be arranged to be spaced apart from each other by the distance D in the first direction, and the plurality of rhombuses can be arranged to be spaced apart from each other by the distance D in the second direction.

[0030] The third pattern can include a dotted line pattern in which line segments are arranged in straight lines and positioned to be spaced apart from each other in the third direction.

[0031] The pattern forming object can be a metal sheet on which a change image is formed by printing. Specifically, the pattern forming object can be a metal sheet used in the above-described manufacturing method. In this case, the change image that is a pattern of the metal sheet is transferred to the injection-molded object. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 (a) of FIG. 1 is a front view of an injection-molded object manufactured by the manufacturing method of the disclosure.

[0033] Figure 1 (b) of FIG. 1 is a diagram showing a pattern of a change image of (a) of FIG. 1 and a pattern in which the patterns overlap each other. Figure 1

[0034] Figure 2 (a) of FIG. 2 is a magnified view of the first pattern.

[0035] Figure 2 (b) of FIG. 2 is a magnified view of the second pattern.

[0036] Figure 2 (c) of FIG. 2 is a magnified view of the third pattern.

[0037] Figure 2 (d) of FIG. 2 is a magnified view of a pattern in which the first pattern, the second pattern, and the third pattern overlap each other.

[0038] Figure 3 FIG. 3 is a partial magnified cross-sectional view of a metal sheet on which a pattern is printed.

[0039] Figure 4 ​(a) in the figure is a diagram showing the injection molding process in which a metal sheet is fixed to a mold.

[0040] Figure 4 (b) in the figure is a diagram showing the injection molding process, in which the mold is clamped.

[0041] Figure 4 (c) in the figure illustrates the injection molding process, in which molten plastic is injected into a mold.

[0042] Figure 4 (d) in the figure illustrates the injection molding process, where the mold is opened and the injection molded part is ejected. Detailed Implementation

[0043] The embodiments of this disclosure will now be described in detail where appropriate, with reference to the accompanying drawings.

[0044] like Figure 1 As shown in (a), as an example of an object on which a pattern is formed by the manufacturing method of this disclosure, the injection-molded object 50 has a pattern M formed by protrusions and depressions on its surface. The surface of the injection-molded object 50 on which the pattern M is formed is raised and the back is recessed. The pattern M is formed by lines formed by long depressions.

[0045] Pattern M changes depending on the viewing angle. This pattern will be referred to below as a "variable image." Figure 1 As shown in (b), the changing image includes a first pattern G1, a second pattern G2, and a third pattern G3.

[0046] The first pattern G1 consists of a plurality of line segments 1 extending in a first direction.

[0047] The second pattern G2 consists of multiple line segments 2 extending in a second direction different from the first direction.

[0048] The third pattern G3 consists of a plurality of line segments 3 extending upward in a third direction different from the first and second directions. In this embodiment, the angle between the first direction and the third direction is equal to the angle between the second direction and the third direction.

[0049] like Figure 1 As shown in (a), pattern M includes a first triangular image M1, a second quadrilateral image M2, and a third image M3 forming the background. The second image M2 overlaps with the first image M1.

[0050] The third image M3 is formed by the third pattern G3. The first image M1 is formed by the first pattern G1 and overlaps with the third image M3. The second image M2 is formed by the second pattern G2 and overlaps with both the first image M1 and the third image M3. The pattern GA is formed (see reference). Figure 1In (b) of the above, the first image M1, the second image M2 and the third image M3 overlap each other. The first pattern G1, the second pattern G2 and the third pattern G3 overlap each other in the pattern GA.

[0051] Because the first image M1 includes the first pattern G1, the first image M1 is more visible from a predetermined direction where the first pattern G1 has higher reflectivity. Because the second image M2 includes the second pattern G2, the second image M2 is more visible from a direction different from the predetermined direction.

[0052] like Figure 2 As shown in (a), the first pattern G1 is composed of a plurality of pattern units P1. Each pattern unit P1 consists of a pair of line segments 1 of the same length. These line segments 1 are arranged side-by-side and positioned to be spaced apart from each other by a distance d in a first width direction perpendicular to the first direction. This distance d is equal to or less than the length L of the line segments 1. The line segments 1 of the pattern unit P1 are positioned to be spaced apart from each other by a distance D in a second direction. The plurality of pattern units P1 are arranged in the first direction and in the first width direction.

[0053] When one of two adjacent pattern units P1 in a first direction is designated as the first pattern unit P11 and the other as the second pattern unit P12, the second pattern unit P12 is positioned such that it is separated from the first pattern unit P11 in the first direction by a distance L1 equal to or less than the length L, and the second pattern unit P12 is offset from the first pattern unit P11 in the first width direction by a distance d1 less than the distance d. The pattern units P1 forming the first pattern G1 are offset from each other by a distance L2 in the second direction.

[0054] In this embodiment, the distance L2 is equal to the length L. The distance L2 can be shorter than the length L.

[0055] like Figure 2 As shown in (b), the second pattern G2 is arranged as a reversed pattern of the pattern unit P1 forming the first pattern G1. Specifically, the second pattern G2 consists of a plurality of pattern units P2. Each pattern unit P2 consists of a pair of line segments 2 having the same length. The length of line segment 2 is equal to the length L of line segment 1. The pair of line segments 2 are arranged side by side and positioned apart by a distance d in a second width direction perpendicular to the second direction. The line segments 2 of the pattern unit P2 are positioned apart by a distance D in a first direction. The plurality of pattern units P2 are arranged in the second direction and in the second width direction.

[0056] When one of two adjacent pattern units P2 in the second direction is designated as the third pattern unit P23 and the other as the fourth pattern unit P24, the fourth pattern unit P24 is positioned at a distance L1 from the third pattern unit P23 in the second direction, and the fourth pattern unit P24 is offset from the third pattern unit P23 by a distance d1 in the second width direction. The pattern units P2 forming the first pattern G2 are offset from each other by a distance L2 in the first direction.

[0057] like Figure 2 As shown in (d), in the region where the first pattern G1 and the second pattern G2 overlap, two line segments 1B and 1C forming the first pattern G1 and two line segments 2B and 2C forming the second pattern G2 form a rhombus R. The length of each side of the rhombus R is equal to the distance L2. Multiple rhombus R are arranged in a first direction and multiple rhombus R are arranged in a second direction. The rhombus R are arranged to be spaced apart from each other by a distance D in the first direction and to be spaced apart from each other by a distance D in the second direction. Two pattern units P1 adjacent to each other in the first width direction include four line segments 1A, 1B, 1C, and 1D. Two line segments 1B and 1C are the two inner line segments of the four line segments 1A, 1B, 1C, and 1D. Two pattern units P2 adjacent to each other in the second width direction include four line segments 2A, 2B, 2C, and 2D. Two line segments 2B and 2C are the two inner line segments of the four line segments 2A, 2B, 2C, and 2D.

[0058] lie in Figure 2 In (d), the outermost line segment 1A of line segment 1B to the upper left (on one side in the first width direction) forms a rhombus R2, which is in Figure 2 In (d), it is located to the upper left of the rhombus R1 formed by line segments 1B and 1C. Figure 2 In (d), the outermost line segment 1D of line segment 1C to the lower right (on the other side in the first width direction) forms a rhombus R3, which in Figure 2 In (d), it is located to the lower right of the rhombus R1 formed by line segments 1B and 1C.

[0059] lie in Figure 2 In (d), the outermost line segment 2A of line segment 2B to the upper right (on one side in the second width direction) forms a rhombus R4, which is in Figure 2 In (d), it is located to the upper right of the rhombus R1 formed by line segments 2B and 2C. Figure 2 In (d), the outermost line segment 2D of line segment 2C to the lower left (on the other side in the second width direction) forms a rhombus R5, which in Figure 2 In (d), it is located to the lower left of the rhombus R1 formed by line segments 2B and 2C.

[0060] As shown in (c) of Figure 3 The third pattern G3 is composed of a plurality of broken line patterns PB in which line segments 3 are arranged in a straight line and positioned to be spaced apart from each other by a distance d2 in the third direction. The broken line patterns PB are arranged side by side and positioned to be spaced apart by a distance d3 that is longer than the distance d2 in a third width direction perpendicular to the third direction. When one of the two broken line patterns PB adjacent to each other in the third width direction is designated as a first broken line pattern PB1 and the other is designated as a second broken line pattern PB2, each of the line segments 3 forming the second broken line pattern PB2 is misaligned in the third direction from the line segments 3 forming the first broken line pattern PB1. Specifically, the first broken line pattern PB1 and the second broken line pattern PB2 are arranged such that the line segments 3 forming the second broken line pattern PB2 are positioned between the two line segments 3 forming the first broken line pattern PB1 in the third direction.

[0061] The line segments 3 of the third pattern G3 are positioned in locations connecting adjacent vertices of two adjacent rhombuses R. Specifically, the distance d2 is equal to the length of the shorter diagonal of the rhombus R. The distance d3 is longer than half the length of the longer diagonal of the rhombus R.

[0062] A method of manufacturing the injection-molded object 50 will be described below.

[0063] In the manufacturing method of the present embodiment, first, as shown in Figure 4 a flat metal sheet 30 (metal sheet preparation step) having a pattern MR of projections and depressions is prepared. Herein, the pattern MR is a pattern in which the projections and depressions of the above-described pattern M are reversed. The metal sheet 30 has a first surface 31 and a second surface 32 opposite the first surface 31.

[0064] In the metal sheet preparation step, first, the first surface 31 of the metal sheet 30 is treated by flame treatment or primer treatment. Next, the pattern MR of elevations is formed on the first surface 31 of the metal sheet 30 by printing. In this case, screen printing or inkjet printing can be used as the method for printing. The ink used for printing is ultraviolet-cured ink. After the ink is applied to the first surface 31 of the metal sheet 30, ultraviolet light can be irradiated on the ink to quickly complete the letterpress printing. Alternatively, thermal imaging can be used in which resin powder is applied to the ink (which is ordinary ink) before the ink dries and the resin powder melts and fixes. The dimensions of the projections and depressions forming the pattern MR in the thickness direction of the metal sheet 30 are smaller than the thickness of the metal sheet 30.

[0065] The material of the metal sheet 30 is not limited as long as the ink can be fixed, but for example, aluminum, aluminum alloy, and steel sheets such as galvanized steel sheets and stainless steel sheets can be used. When the metal sheet 30 is made of aluminum or an aluminum alloy, the thickness of the metal sheet 30 can be equal to or greater than 0.05 mm and equal to or less than 2 mm. When the metal sheet 30 is made of a steel sheet, the thickness of the metal sheet 30 can be equal to or greater than 0.01 mm and equal to or less than 0.7 mm.

[0066] As shown in (a) of FIG. 10, after the metal sheet 30 is prepared, the metal sheet 30 is fixed to an injection mold 40 having a recessed inner surface 42A with the second surface 32 facing the inner surface 42A of the mold 40 and the first surface 31 facing a cavity of the mold 40 (fixing step). Figure 4

[0067] Specifically, in one example, the mold 40 includes a fixed mold 41 and a movable mold 42, and the movable mold 42 has the recessed inner surface 42A. The fixed mold 41 has a protruding inner surface 41A corresponding to the recessed inner surface 42A. Either the fixed mold 41 or the movable mold 42 can have the recessed inner surface 42A. The movable mold 42 can have a pin PN for fixing the metal sheet 30. In this case, a hole 35 engaging the pin PN can be formed in the metal sheet 30.

[0068] When the metal sheet 30 is fixed to the mold 40, the metal sheet 30 is preferably but not necessarily fixed to a flat portion 44 located outside the recessed inner surface 42A. An adhesive or a double-sided tape can be used when the metal sheet 30 is fixed to the mold 40. In a state where the metal sheet 30 is fixed to the mold 40, because the metal sheet 30 is a flat sheet, the metal sheet 30 is in contact with the recessed inner surface 42A only by being fixed to the movable mold 42 (refer to the dotted line).

[0069] As shown in (b) of FIG. 10, when the mold 40 is clamped (clamping step), the metal sheet 30 is elongated by being pushed by the protruding inner surface 41A but does not completely contact the recessed inner surface 42A. In the mold 40 of the present embodiment, the cavity of the filling material is a space between the metal sheet 30 and the protruding inner surface 41A (a space in which the molten plastic MP is filled in the subsequent forming step). Figure 4 As shown in (c) of FIG. 10, the molten plastic MP is injected into the cavity, and the pressure of the molten plastic MP plastically deforms the metal sheet 30. The second surface 32 is pressed against the recessed inner surface 42A of the mold 40, and the pattern MR of the first surface 31 is transferred to a product surface PS of the molten plastic MP (forming step).

[0070] Figure 4 Next, as shown in (d) of FIG. 10, the mold 40 is opened, and the metal sheet 30 is removed from the mold 40 (removing step). The product 1 is obtained by the molten plastic MP being solidified in the mold 40.

[0071] Next, as shown in (d) of FIG. 10, the mold 40 is opened, and the metal sheet 30 is removed from the mold 40 (removing step). The product 1 is obtained by the molten plastic MP being solidified in the mold 40. ​ ​​After the molten plastic MP is solidified, the injection-molded object 50 is removed, and the metal sheet 30 is left in the mold 40 (ejection step) as indicated in (d) in FIG. 6. If runners 59 or the like remain on the injection-molded object 50, the runners 59 are removed. The protrusions and depressions of the first surface 31 of the metal sheet 30 are transferred to the surface of the injection-molded object 50, and a pattern M is formed. The pattern M is a pattern formed by the depressions 53.

[0072] After the first injection-molded object 50 is manufactured by the mold 40, the plastically deformed metal sheet 30 remains in the movable mold 42, and the metal sheet 30 is in close contact with the inner surface 42A of the movable mold 42. Therefore, when a subsequent second injection-molded object 50 is manufactured, injection molding can be performed using the metal sheet 30 that is in close contact with the inner surface 42A.

[0073] According to the above-described method for manufacturing the injection-molded object of the present embodiment, the following advantageous effects can be obtained.

[0074] Since the flat metal sheet 30 is plastically deformed in the molding step, the metal sheet 30 remains inside the movable mold 42 after the injection-molded object is ejected, and the metal sheet 30 cooperates with the inner surface 42A of the movable mold 42. After the injection-molded object 50 is repeatedly manufactured, the metal sheet 30 is not easily broken. Therefore, the durability of the member for transferring a pattern to an injection-molded object can be increased.

[0075] Since the first surface 31 of the metal sheet 30 is surface-treated by flame treatment or primer treatment, the ink is less likely to be peeled off from the first surface 31, and thus the frequency of replacing the metal sheet can be reduced.

[0076] By forming the metal sheet 30 made of aluminum or an aluminum alloy with a thickness equal to or greater than 0.05 mm, it is possible to suppress a problem such as breakage of the metal sheet 30 when the metal sheet 30 is plastically deformed. Likewise, by forming the metal sheet 30 made of aluminum or an aluminum alloy with a thickness equal to or less than 2 mm, the metal sheet 30 can be plastically deformed by the pressure of the molten plastic MP until the metal sheet 30 is in close contact with the inner surface 42A of the movable mold 42.

[0077] By forming the metal sheet 30 made of a steel sheet with a thickness greater than or equal to 0.01 mm, it is possible to suppress a problem such as breakage of the metal sheet 30 when the metal sheet 30 is plastically deformed. Likewise, by forming the metal sheet 30 made of a steel sheet with a thickness equal to or less than 0.7 mm, the metal sheet 30 can be plastically deformed by the pressure of the molten plastic MP until the metal sheet 30 is in close contact with the inner surface 42A of the movable mold 42.

[0078] While the embodiments of the present application have been described above, the present application is not limited to the above-described embodiments and can be modified and implemented in various forms.

[0079] For example, in the above-described embodiment, the protrusions and depressions are formed on the metal sheet 30 by printing. However, in the metal sheet preparation step, the protrusions and depressions can be formed on the first surface of the metal sheet by laser engraving, machining, or work of an artisan.

[0080] Further, the metal sheet can be made by another person.

[0081] The pattern is not limited to a changing image, and can be any pattern.

[0082] If the first mold having a recessed inner surface among the first mold and the second mold constituting the mold has an inlet for injecting molten plastic, the metal sheet can be placed in the mold with the first surface of the metal sheet facing the recessed inner surface of the first mold. In this case, when molten plastic is injected, the second surface of the metal sheet is pressed against the protruding inner surface of the second mold.

[0083] To form an image consisting of a plurality of diamonds arranged at a distance D from each other in a first direction and a plurality of diamonds arranged at a distance D from each other in a second direction, the second pattern unit can not be offset with respect to the first pattern unit in the first width direction. In other words, the second pattern unit and the first pattern unit can be arranged in a row and positioned at a distance from each other in the first direction. The same applies to the third pattern unit and the fourth pattern unit. When the first pattern unit and the second pattern unit are offset in the first width direction as in the above-described embodiment, the space between two diamonds adjacent in the longitudinal direction of the diamond can be made smaller.

[0084] The elements described in the above-described embodiment and its modified examples can be selectively and combinatively implemented.

Claims

1. A method for manufacturing an injection-molded object, the method comprising: Prepare a flat metal sheet having a first surface and a second surface opposite to the first surface, the first surface having a pattern formed by protrusions and indentations; The metal sheet is fixed to a mold for injection molding, wherein the first surface of the metal sheet faces the cavity of the mold, and a space is provided between a portion of the second surface and the inner surface of the mold; Clamp the mold; The injection-molded object is formed by injecting molten plastic into the cavity, pressing the portion of the second surface against the inner surface of the mold by the pressure of the molten plastic to plastically deform the metal sheet to make it in close contact with the inner surface of the mold, and transferring the pattern formed on the first surface to the product surface of the molten plastic. as well as After the molten plastic has solidified, the injection-molded object is ejected while the metal sheet remains in close contact with the inner surface of the mold.

2. The method for manufacturing injection-molded objects according to claim 1, wherein, The metal sheet is prepared by forming a raised pattern on the first surface through printing.

3. The method for manufacturing injection-molded objects according to claim 2, wherein, The preparation of the metal sheet includes treating the first surface by flame treatment or primer treatment, and then forming the pattern by printing on the first surface.

4. The method for manufacturing an injection-molded article according to any one of claims 1 to 3, wherein, The metal sheet is made of aluminum or an aluminum alloy.

5. The method for manufacturing injection-molded objects according to claim 4, wherein, The thickness of the metal sheet is equal to or greater than 0.05 mm and equal to or less than 2 mm.

6. The method for manufacturing an injection-molded article according to any one of claims 1 to 3, wherein, The metal sheet is made of steel plate.

7. The method for manufacturing injection-molded objects according to claim 6, wherein, The thickness of the metal sheet is equal to or greater than 0.01 mm and equal to or less than 0.7 mm.

Images