Pattern-forming object, injection-molded object, and method of manufacturing 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 on a mold for injection molding; the mold is clamped; forming an injection molded object; and discharging the injection molded object. The metal sheet has a first surface on which a pattern is formed and a second surface opposite the first surface. The sheet metal is secured to the mold with the first surface facing a cavity of the mold. And 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 discharged from the mold with the metal sheet remaining in the mold.

Description

[0001] Citation of Related Applications

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

[0003] Generally, it is known to prepare a mold surface molding sheet, which is a plastic film on which a pattern including fine lines with fine line spacing is formed by screen printing, and the mold surface molding sheet is arranged inside the mold to transfer the pattern to the surface of the 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. Deep creases are formed on the mold surface molding sheet at portions where the shape of the mold changes, such as at the boundary between the cavity and the parting line. There is a problem that the mold surface molding sheet becomes fragile at the deep creases and may cause the mold surface molding sheet to break.

[0004] On the other hand, the inventors of the present disclosure have invented a method for manufacturing an injection molded object, wherein a mold surface molding sheet made of an elastomer having a pattern formed of protrusions and depressions is disposed inside a mold to transfer the pattern to 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, the durability is increased compared to a plastic film. Summary of the invention

[0005] In the above-mentioned mold surface molding sheet, repeated injection molding causes deep creases to be formed in parts where there is a shape change, such as at the boundary between the cavity and the parting line, which may 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 used to transfer 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 the injection molded object; and ejecting 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 to 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, wherein the first surface faces 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 into 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 ejecting the injection molded object, after the molten plastic is solidified, the injection molded object is ejected from the mold with the metal sheet remaining inside the mold.

[0013] Because the flat metal sheet is plastically deformed in the step of forming the injection molded object, after the injection molded object is ejected, the metal sheet remains inside the mold, where the metal sheet is in close contact with the inner surface of the mold. After repeated production of the injection molded object, 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, a ridge pattern can be formed on the first surface 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 a pattern can be formed on a first surface by printing.

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

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

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

[0019] Since 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 may be made of sheet steel.

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

[0022] Since the thickness of the metal sheet made of the steel plate is 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 patterned object suitable for being manufactured in or for being used in the above-mentioned manufacturing method.

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

[0025] The changing 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 are positioned to be spaced apart 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 a length L in the first direction, and the second pattern unit is offset from the first pattern unit in the first width direction by a distance d1 shorter than a distance d.

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

[0029] The pattern units forming the first pattern may be offset from each other by a distance L2 in the second direction. The pattern units forming the second pattern may be offset from each other by a 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 a distance D in the first direction. In the area where 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. The length of each side of the rhombus may be equal to the length L2. A plurality of rhombuses may be arranged to be spaced apart from each other by a distance D in the first direction, and a plurality of rhombuses may be arranged to be spaced apart from each other by a distance D in the second direction.

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

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

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

[0033] Figure 1 (b) shows the formation of Figure 1 Illustration of patterns of a changing image in (a) and patterns in which the patterns overlap each other.

[0034] Figure 2 (a) in FIG. 1 is an enlarged view of the first pattern.

[0035] Figure 2 (b) in FIG. 1 is an enlarged view of the second pattern.

[0036] Figure 2 (c) in FIG. 1 is an enlarged view of the third pattern.

[0037] Figure 2 (d) in FIG. 1 is an enlarged view of a pattern in which the first pattern, the second pattern, and the third pattern overlap with each other.

[0038] Figure 3 is a partially enlarged cross-sectional view of a metal sheet having a pattern printed thereon.

[0039] Figure 4(a) is a diagram showing an injection molding step in which a metal sheet is fixed to a mold.

[0040] Figure 4 (b) in FIG. 1 is a diagram showing an injection molding step in which the mold is clamped.

[0041] Figure 4 (c) is a diagram showing the injection molding step, in which molten plastic is injected into a mold.

[0042] Figure 4 (d) in FIG. 1 is a diagram showing an injection molding step, in which the mold is opened and the injection-molded product is ejected. DETAILED DESCRIPTION

[0043] Next, embodiments of the present disclosure will be described in detail with reference to the drawings where appropriate.

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

[0045] The pattern M changes according to the angle of observation. This pattern is hereinafter referred to as a "changing image". Figure 1 As shown in (b) of FIG. 8 , the changing image includes a first pattern G1 , a second pattern G2 and a third pattern G3 .

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

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

[0048] The third pattern G3 is composed of a plurality of line segments 3 extending in a third direction different from the first direction and the second direction. 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) of FIG. 1 , the pattern M includes a triangular first image M1, a quadrilateral second image M2, and a third image M3 forming a background. The second image M2 overlaps 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 the first image M1 and the third image M3. Figure 1(b)), wherein 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 a 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) of FIG. 1 , the first pattern G1 is composed of a plurality of pattern units P1. The pattern unit P1 is composed of a pair of line segments 1 having the same length. The pair of line segments 1 are arranged side by side and are positioned to be spaced apart from each other by a distance d in a first width direction perpendicular to the first direction, and the distance d is equal to or less than the length L of the line segment 1. The line segments 1 of the pattern unit P1 are positioned to be spaced apart from each other by a distance D in the second direction. The plurality of pattern units P1 are arranged in the first direction and the plurality of pattern units P1 are arranged in the first width direction.

[0053] When one of two pattern units P1 adjacent to each other in the first direction is designated as a first pattern unit P11 and the other pattern unit is designated as a second pattern unit P12, the second pattern unit P12 is positioned to be spaced apart 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 may be shorter than the length L.

[0055] like Figure 2 As shown in (b) of the figure, the second pattern G2 is arranged to form a pattern inverted from the pattern unit P1 of the first pattern G1. Specifically, the second pattern G2 is composed of a plurality of pattern units P2. The pattern unit P2 is composed of a pair of line segments 2 having the same length. The length of the line segment 2 is equal to the length L of the line segment 1. A pair of line segments 2 are arranged side by side and positioned to be separated 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 to be separated by a distance D from each other in the first direction. A plurality of pattern units P2 are arranged in the second direction and a plurality of pattern units P2 are arranged in the second width direction.

[0056] When one of two pattern units P2 adjacent to each other in the second direction is indicated as a third pattern unit P23 and the other pattern unit is indicated as a fourth pattern unit P24, the fourth pattern unit P24 is positioned to be spaced apart from the third pattern unit P23 by a distance L1 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 area where the first pattern G1 overlaps with the second pattern G2, 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. A plurality of rhombuses R are arranged in the first direction and a plurality of rhombuses R are arranged in the second direction. The rhombuses R are arranged to be spaced apart from each other by a distance D in the first direction, and the rhombuses R are arranged 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. The two line segments 1B and 1C are two line segments on the inner side 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. The two line segments 2B and 2C are two line segments on the inner side of the four line segments 2A, 2B, 2C and 2D.

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

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

[0060] like Figure 2 As shown in (c) in FIG. 1 , the third pattern G3 is composed of a plurality of dotted line patterns PB, wherein the 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 dotted line patterns PB are arranged side by side and positioned to be spaced apart by a distance d3 longer than the distance d2 in the third width direction perpendicular to the third direction. When one of the two dotted line patterns PB adjacent to each other in the third width direction is designated as the first dotted line pattern PB1 and the other dotted line pattern is designated as the second dotted line pattern PB2, each of the line segments 3 forming the second dotted line pattern PB2 is not aligned with the line segments 3 forming the first dotted line pattern PB1 in the third direction. Specifically, the first dotted line pattern PB1 and the second dotted line pattern PB2 are arranged so that the line segment 3 forming the second dotted line pattern PB2 is located between the two line segments 3 forming the first dotted line pattern PB1 in the third direction.

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

[0062] Next, a method of manufacturing the injection molded object 50 will be described.

[0063] In the manufacturing method of this embodiment, first, Figure 3 As shown, a flat metal sheet 30 having a pattern MR formed by projections and depressions is prepared (metal sheet preparation step). Herein, the pattern MR is a pattern in which the projections and depressions of the above-mentioned pattern M are reversed. The metal sheet 30 has a first surface 31 and a second surface 32 opposite to 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, a raised pattern MR 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 a method for printing. The ink used for printing is an ultraviolet curing 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 relief printing. Alternatively, thermal imaging can be used, in which resin powder is applied to the ink (which is a normal ink) before the ink dries and the resin powder melts and fixes. The size of the protrusions and depressions forming the pattern MR in the thickness direction of the metal sheet 30 is 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 plate such as galvanized steel plate and stainless steel plate can be used. When the metal sheet 30 is made of aluminum or 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 steel plate, 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] like Figure 4 As shown in (a), after the metal sheet 30 is prepared, the metal sheet 30 is fixed to an injection mold 40 having a concave inner surface 42A, wherein the second surface 32 faces the inner surface 42A of the mold 40 and the first surface 31 faces the cavity of the mold 40 (fixing step).

[0067] Specifically, in one example, the mold 40 includes a fixed mold 41 and a movable mold 42, and the movable mold 42 has a concave inner surface 42A. The fixed mold 41 has a raised inner surface 41A corresponding to the concave inner surface 42A. Either the fixed mold 41 or the movable mold 42 may have a concave inner surface 42A. The movable mold 42 may have a pin PN for fixing the metal sheet 30. In this case, the hole 35 engaging the pin PN may 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 the flat portion 44 located outside the concave inner surface 42A. When the metal sheet 30 is fixed to the mold 40, an adhesive or a double-sided tape may be used. In a state where the metal sheet 30 is fixed to the mold 40, since the metal sheet 30 is a flat sheet, the metal sheet 30 does not closely contact the concave inner surface 42A (see the dotted line) only by being fixed to the movable mold 42.

[0069] like Figure 4 As shown in (b) in FIG. 4 , when the mold 40 is clamped (clamping step), the metal sheet 30 is extended by being pushed by the protruding inner surface 41A, but does not completely contact the concave inner surface 42A. In the mold 40 of this embodiment, the cavity filled with the material is the space between the metal sheet 30 and the raised inner surface 41A (the space filled with the molten plastic MP in the subsequent molding step).

[0070] like Figure 4 As shown in (c) in FIG. 1 , 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 concave inner surface 42A of the mold 40, and the pattern MR of the first surface 31 is transferred to the product surface PS of the molten plastic MP (forming step).

[0071] Next, if Figure 4As shown in (d) in FIG. 4 , 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 (discharging step). If the runner 59 and the like are left on the injection molded object 50, the runner 59 is removed. The projections 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 the subsequent second injection molded object 50 is manufactured, injection molding can be performed using the metal sheet 30 in close contact with the inner surface 42A.

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

[0074] Since the flat metal sheet 30 is plastically deformed in the forming step, the metal sheet 30 remains inside the movable mold 42 even after the injection molded object is ejected, and the metal sheet 30 is fitted with the inner surface 42A of the movable mold 42. After repeated production of the injection molded object 50, the metal sheet 30 is not easily broken. Therefore, the durability of the member for transferring a pattern to the 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 fall 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 problems such as cracking 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 closely contacts the inner surface 42A of the movable mold 42.

[0077] By forming the metal sheet 30 made of a steel plate having a thickness greater than or equal to 0.01 mm, it is possible to suppress problems such as cracking of the metal sheet 30 when the metal sheet 30 is plastically deformed. Likewise, by forming the metal sheet 30 made of a steel plate having 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 closely contacts the inner surface 42A of the movable mold 42.

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

[0079] For example, in the above-described embodiment, projections and depressions are formed on the metal sheet 30 by printing. However, in the metal sheet preparation step, projections and depressions may be formed on the first surface of the metal sheet by laser engraving, machining, or craftsman's work.

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

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

[0082] If the first mold having the concave inner surface of 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 concave inner surface of the first mold. In this case, when the molten plastic is injected, the second surface of the metal sheet is pressed against the raised inner surface of the second mold.

[0083] In order to form an image composed of a plurality of rhombuses arranged at a distance D from each other in the first direction and a plurality of rhombuses arranged at a distance D from each other in the second direction, the second pattern unit may not be offset relative to the first pattern unit in the first width direction. In other words, the second pattern unit and the first pattern unit may be arranged in a row and positioned at a distance from each other in the first direction. The same is true for 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-mentioned embodiment, the space between two adjacent rhombuses in the longitudinal direction of the rhombus can be made smaller.

[0084] The elements described in the above-mentioned embodiments and their modified examples may be implemented selectively and in combination.

Claims

1. A method for manufacturing an injection molded object, the method comprising: preparing a flat metal sheet, the 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 depressions; fixing the metal sheet to a mold for injection molding, wherein the first surface of the metal sheet faces a cavity of the mold and a space is provided between a portion of the second surface and an inner surface of the mold; Clamp the mold; forming the injection molded object by injecting molten plastic into the cavity, pressing the portion of the second surface against the inner surface of the mold so that the metal sheet is plastically deformed by the pressure of the molten plastic, and transferring the pattern formed on the first surface to a product surface of the molten plastic; as well as After the molten plastic solidifies, the injection molded object is ejected with the metal sheet remaining in the mold.

2. The method for producing an injection molded object according to claim 1, wherein: Preparing the metal sheet includes forming a pattern of ridges on the first surface by printing.

3. The method for producing an injection molded object according to claim 2, wherein: Preparing the metal sheet includes treating the first surface by flame treatment or primer treatment, and then forming the pattern on the first surface by printing.

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

5. The method for producing an injection molded object 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 producing an injection-molded object according to any one of claims 1 to 3, wherein: The metal sheet is made of steel plate.

7. The method for producing an injection molded object 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.

8. A pattern-forming object on which an image as a pattern is formed, the image being a changing image that changes according to an observation angle, wherein: The change image includes: a first pattern consisting of a plurality of line segments extending in a first direction; a second pattern consisting of a plurality of line segments extending in a second direction different from the first direction; and a third pattern consisting of a plurality of line segments extending in a third direction different from the first direction and the second direction, wherein 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 are positioned to be spaced apart from each other by a distance d shorter than a length L of the line segments in a first width direction perpendicular to the first direction, and 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, and Wherein, 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 equal to or less 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.

9. The patterned object according to claim 8, wherein: The second pattern is composed of a plurality of pattern units, each of which is composed of a pair of line segments having the same length, the pair of line segments being arranged side by side and positioned to be spaced apart from each other by the distance d in a second width direction perpendicular to the second direction, and the plurality of pattern units of the second pattern are arranged in the second direction, and the plurality of pattern units of the second pattern are arranged in the second width direction, and Wherein, when one of two pattern units adjacent to each other in the second direction is designated as a third pattern unit and the other of the two pattern units is designated as a fourth pattern unit, the fourth pattern unit is positioned to be separated from the third pattern unit by the distance L1 in the second direction, and the fourth pattern unit is offset from the third pattern unit by the distance d1 in the second width direction.

10. The patterned object according to claim 9, wherein: The pattern units forming the first pattern are offset from each other by a distance L2 in the second direction, and the pattern units forming the second pattern are offset from each other by a distance L2 in the first direction, Two line segments of the pattern unit forming the first pattern are positioned to be spaced apart from each other by a distance D in the second direction, Two line segments of the pattern unit forming the second pattern are positioned to be spaced apart from each other by a distance D in the first direction, and In the area where the first pattern and the second pattern overlap, two line segments included in two adjacent pattern units of the first pattern that are adjacent to each other in the first width direction and two line segments included in two adjacent pattern units of the second pattern that are adjacent to each other in the second width direction form a rhombus, the length of each side of the rhombus is equal to the length L2, and a plurality of the rhombuses are arranged to be spaced apart from each other by the distance D in the first direction, and a plurality of the rhombuses are arranged to be spaced apart from each other by the distance D in the second direction.

11. The patterned object according to claim 10, wherein: The third pattern includes a dotted line pattern in which line segments are arranged in a straight line and are positioned to be spaced apart from each other in the third direction.

12. The patterned object according to claim 8, wherein: The object is a metal sheet on which the changing image is formed by printing.

13. An injection molded object having an image formed thereon as a pattern, the image being a changing image that changes depending on an observation angle, wherein The change image includes: a first pattern consisting of a plurality of line segments extending in a first direction; a second pattern consisting of a plurality of line segments extending in a second direction different from the first direction; as well as a third pattern consisting of a plurality of line segments extending in a third direction different from the first direction and the second direction, wherein 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 are positioned to be spaced apart from each other by a distance d shorter than a length L of the line segments in a first width direction perpendicular to the first direction, and 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, and Wherein, 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 equal to or less 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.

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