Patent Publication Number: US-2002006475-A1

Title: Marking method and marked molding

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a marking method of displaying characters and patterns on moldings by laser beam, electron beam, heat ray or other energy ray, and to marked moldings.  
       BACKGROUND OF THE INVENTION  
       [0002] The following methods have been known conventionally as the marking method on resin molding by using energy ray such as laser beam. As disclosed in Japanese Patent Publication No. 61-11771 and Japanese Patent Publication No. 62-59663, a resin is mixed with a filler which is deformed by the action of the laser beam or energy ray, and the mixture is injection-molded to obtain a resin molding. The resin molding is exposed to energy rays such as a laser beam to be partly discolored, so that a desired character or pattern is formed. As disclosed in Japanese Laid-open Patent No. 60-4094 and Japanese Laid-open Patent No. 1-267092, a plurality of coat films are formed on the surface of a resin molding by applying paints of different colors and only the surface layer or a plurality of coat films are partially removed by a laser beam, so that the desired color is left over.  
       [0003] Exemplary conventional methods are described below while referring to FIG. 12 and FIG. 13. FIG. 12 is a front view for explaining a method of discoloring the filler in the resin molding, and FIG. 13 is a sectional front view for explaining a method of removing the coat film of the paint on the resin molding. In FIG. 12, the surface layer containing a paint powder  4  which is discolored by the action of a laser beam is formed on the surface of a resin molding  3 . A laser beam  1  controlled by a deflection device  2  is emitted to the surface layer, and the portion exposed to the laser beam is changed in color, and a mark  5  is formed. As the laser beam  1  is emitted by deflection control according to the desired character or pattern, the mark  5  is formed on the surface layer of the resin molding  3 .  
       [0004] In FIG. 13, three color paints are applied sequentially on the surface of a resin molding  6 , and three layers of coat films  7 ,  8 ,  9  are formed. A laser beam  1  controlled by a deflection device  2  is controlled in reflection according to the emitting position corresponding to a desired character or pattern, and is also controlled in the amount of energy, and is emitted to the surface coat film  7  side of the resin molding  6 . Depending on the amount of energy, the coat film  7 , coat film  8  or coat film  9  having a different color is cut off, and characters and patterns having different colors are formed as required.  
       [0005] However, in the conventional marking method by making use of discoloration of the filler of the resin molding by laser beam, characters or patterns of different colors cannot be formed on one resin molding. On the other hand, in the conventional marking method by removing the coat film partly by irradiation with laser beam by preliminarily formed coat films on the surface of the resin molding, by forming coat film layers in multiple layers by different colors, combination of various color marks is possible, but it requires more steps in coating and drying.  
       [0006] It is hence an object of the invention to present a method of marking desired characters or patterns, and making the molding with different colors, not limited in mark color, at low cost.  
       SUMMARY OF THE INVENTION  
       [0007] The marking method of forming a mark on a molding of the present invention comprises (a) a step of feeding a film having a first surface and a second surface, (b) adhering, fixing, affixing or disposing a paint on the first surface of the film wherein the paint has a lower melting point than the film, (c) a step of positioning the film on the surface of a molding so that the paint contacts the surface of the molding, and (d) a step of forming a mark by emitting an energy ray from the second surface side of the film, and transferring and disposing the paint positioned on the first surface of the illuminated portion on the surface of the molding, thereby forming a mark.  
       [0008] The marked molding of the present invention is a molding manufactured by the above method.  
       [0009] Preferably, the molding is a resin molding formed of a material containing resin.  
       [0010] Preferably, the molding has at least one surface selected from the group consisting of (i) curved surface, (ii) concave surface, (iii) convex surface, (iv) convexo-concave surface, and (v) flat surface.  
       [0011] Preferably, the molding has a coarser surface roughness than the first surface of the film.  
       [0012] Preferably, the energy ray is controlled in emitting position by a deflection device.  
       [0013] Preferably, the energy ray is emitted on the paint by passing through the film without causing any effects on the film.  
       [0014] Preferably, the energy ray is a laser beam.  
       [0015] Preferably, the paint component has a specific color, and the mark has the specific color.  
       [0016] Preferably, the paint component contains at least one of dye and pigment.  
       [0017] Preferably, the paint can be melted by irradiation with the energy ray, and when the film is irradiated with the energy ray, the paint is melted and transferred to the surface of the molding.  
       [0018] Preferably, the paint can be sublimated when irradiated with the energy ray, and when the film is irradiated with the energy ray, the paint is sublimated and transferred to the surface of the molding.  
       [0019] In accordance with the present invention, a mark with a desired color can be formed on a molding. The mark is formed easily and inexpensively. A mark having an excellent wear resistance is formed. A mark having an excellent precision is easily formed on the surface of a molding having a complicated shape. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020]FIG. 1 is a front view for explaining a marking method on a molding in a first embodiment of the present invention.  
     [0021]FIG. 2 is a perspective view showing a marking execution state in the first embodiment.  
     [0022]FIG. 3 is a perspective view showing a marking finished state in the first embodiment.  
     [0023]FIG. 4 is a sectional view showing a marking finished state in the first embodiment.  
     [0024]FIG. 5 is a perspective view showing deflection of a film on a wide molding surface.  
     [0025]FIG. 6 is a perspective view showing a film adhering method to the wide molding surface in the first embodiment.  
     [0026]FIG. 7 is a front view showing a film adhering method to a molding having a convex surface in the first embodiment.  
     [0027]FIG. 8 is a sectional view showing a film adhering method to a molding having a convex surface in the first embodiment.  
     [0028]FIG. 9 is a sectional view showing a film adhering method on a molding having a concave surface in the first embodiment.  
     [0029]FIG. 10 is sectional view for explaining a marking method according to a second embodiment of the present invention.  
     [0030]FIG. 11 is a perspective view of a keyboard as an input device used in an electronic information appliance manufactured by a marking method of the present invention.  
     [0031]FIG. 12 is a front view for explaining a marking method on a resin molding in a prior art.  
     [0032]FIG. 13 is an essential sectional front view for explaining a marking method on a resin molding in other prior art. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0033] A marking method in an embodiment of the invention comprises a step of feeding a film made of a heat resistant resin having a paint placed on a first surface, a step of contacting the paint side to the surface of a molding as the object of transfer, a step of emitting an energy ray controllable in emitting position by a deflection device on a second surface at the back side of the film free from paint, and a step of transferring and fixing the paint only in the illuminated portion to the surface of the molding from the film surface. In this method, regardless of the molding as the object of transfer, the color of the mark can be changed by replacing the film made of heat resistant resin preliminarily coated with paint. As a result, moldings marked with desired colors are obtained easily and at low cost.  
     [0034] In accordance with the present invention, by using a sublimating dye as the paint, it is preferred to vaporize the dye by irradiation with energy ray, and mark by permeating the dye vaporized from the surface of the molding. In this method, the mark permeating to the surface layer of the molding is obtained. As a result, a mark having an excellent wear resistance is formed.  
     [0035] In accordance with the present invention, which utilizes a transparent or translucent film made of heat resistant resin, it is preferred to mark by emitting a YAG laser beam having a short wavelength. The YAG laser beam is a beam generated from an apparatus using yttrium-aluminum-garnet material. Since the YAG laser beam is short in wavelength, the beam penetrates through the film completely and the energy is concentrated on the surface layer of the molding, and therefore the texture of the surface layer is activated, and fixing of fused paint or permeation of vaporized paint is easier. As a result, a clearer mark, which is excellent in wear resistance is formed.  
     [0036] In addition, the thickness of the film is preferred to be about 10 micrometers to about 200 micrometers. In this method, since the film has an adequate strength, the film can be handled easily by a machine, and the transmissivity of energy ray is superior. Hence, melting or transfer of the paint disposed on the film, or vaporization of paint is easy.  
     [0037] In addition to the foregoing, the film of the present invention has a specified thickness and a specified folding and bending hardness. While holding both sides of the film so as to have a U-form deflection with the paint applied first surface on the outside, the first surface having the paint disposed thereon is pressed to contact tightly with the surface of the molding, and the energy ray is emitted from the back side of the film in this state. In this method, using a simple marking device, the film is tightly formed on the molding, and a desired mark is provided.  
     [0038] In another embodiment, when the surface of the molding to be marked has a convex part, while the first surface of the film having the paint disposed thereon is held in a state of covering the convex part of the molding, the film is pulled from both sides, so that the film contacts the surface of the convex part to be marked, and energy ray is emitted in this state. In this method, the film can be contacted tightly to the molding having a convex appearance, so that the desired mark can be formed at an appropriate position.  
     [0039] In another embodiment, when the surface of the molding to be marked has a convex part, while the first surface of the film having the paint disposed thereon is held in a state of covering the convex part, the surrounding of the molding is evacuated, so that the film contacts the surface of the convex part to be marked, and laser beam or energy ray is emitted in this state. The film can be contacted tightly to the molding having a convex appearance, so that the desired mark can be formed.  
     [0040] In yet another embodiment, the paint is a paint mixed with a peelable adhesive having a tacky adhesiveness. Using an elastic piece having a shape corresponding to the surface shape of the molding to be marked, by pressing the film which is coated with the paint on one side, the film tightly contacts the surface of the molding. An energy ray is then emitted. According to this embodiment, the side of the film having the tacky adhesive paint is contacted and held on the surface of the molding to be marked. Accordingly, on the surface of the molding having various shapes such as flat, convex, concave or other surface, the film can be appropriately adhered tightly, and therefore a desired mark can be formed, and then the film can be easily peeled off.  
     [0041] As a result of this marking method, marked moldings having various marks can be manufactured. Specifically, marks having various colors, desired characters and patterns, and moldings having excellent wear resistant marks can be obtained.  
     [0042] With regard to the molding, a thermoplastic resin is preferred. In this case, the degree of freedom of selection of materials for molding is large. Hence, it is possible to utilize various colors, shapes, colors, and patterns. The molding main body is used in the key top of a keyboard used as an input device of an electronic information appliance. In this constitution, key tops of different marks in a same shape, or one key top having colors in plural colors will provide marks of high quality and excellent wear resistance. Usable materials for the molding include thermoplastic resin, thermosetting resin, compound resin containing filler, ceramic materials, metal materials, and others. In particular, the resin is preferable for the molding, and the above effects will be further enhanced in this case.  
     [0043] In this constitution, as the energy ray, laser beam, electron beam, electron ray, heat ray, and other energy ray having high energy may be used.  
     [0044] Preferred embodiments of marking method and marked molding of the invention are described below while referring to the drawings.  
     Exemplary Embodiment 1  
     [0045]FIG. 1 is a front view for explaining a marking method on a resin molding in accordance with a first embodiment of the present invention. FIG. 2 is a perspective view showing a marking execution state. FIG. 3 is a perspective view showing a completed marking. FIG. 4 is a sectional view showing a finished marking and paint transferred state.  
     [0046] Referring to FIGS.  1 - 4 , a marking apparatus comprises a laser beam generator  16 , a deflector  15  for controlling deflection of a laser beam, a laser beam  14  controlled by the deflector  15 , a support stand  17  for positioning and supporting a resin molding  11 , and a paint  13  disposed to one side of a film  12  made of polyethylene terephthalate (PET). The upper surface of the resin molding  11  in this embodiment has a flat shape. The PET film  12  is made of a thermoplastic heat resistant resin. The PET film  12  is colorless and transparent. The thickness of the film  12  is preferred to be in a range of about 10 micrometer to about 200 micrometer. The PET film having this thickness has an adequate strength, and when marking by using the marking apparatus, it is easy to handle. The PET film of this thickness also has an excellent transmissivity to laser beam. If the thickness of the film  12  is less than 10 micrometer, the film may be torn. If the thickness of the film  12  exceeds 200 micrometer, the contact of the film  12  and the molding may be inferior. Further, the PET film has a fine or smooth surface of smaller surface roughness than the surface of the resin molding  11 . That is, the resin molding  11  has a surface roughness so as to receive the molten or sublimated paint. The deflector  15  controls the deflection of the laser beam by the numerical control (NC) data.  
     [0047] The marking procedure by such a marking apparatus is explained below. At a specified position beneath the deflector  15 , the resin molding  11  is placed and positioned. Next, a film coated with the paint  13  on one side is prepared. The surface of the paint  13  of the film  12  held parallel to the upper surface of the resin molding  11  is pressed so as to contact the upper surface of the resin molding  11 . Then, the laser beam  14  emitted from the laser beam source  16  is emitted with a specified intensity to the second surface opposite to the coating side of the paint  13  of the film  12  through the deflector  15 . The laser beam  14  generates heat locally by acting on the film  12  and the paint  13  at its lower side and the resin molding  11  beneath it.  
     [0048] By this heat, the paint  13  is melted, and is transferred and disposed onto the surface of the resin molding  11  having a coarser surface than the film  12 . Herein, the emitting position of the laser beam  14  is moved by the deflector  15  according to the NC data. The paint in the melted portion locally heated by the irradiation with the laser beam is cooled naturally, and is affixed to the surface of the resin molding  11 . In other portion after moving of the laser  14 , the paint is heated and changed similarly. By operating such action continuously, as shown in FIG. 3 and FIG. 4, the paint  13  is transferred from the film  12  to the surface of the resin molding  11 . In this method, a mark  18  such as desired character or pattern is formed on the surface of the resin molding  11 .  
     [0049] Thus, according to the first embodiment, the paint disposed on the film can be easily transferred to the surface of the resin molding. Moreover, plural films provided with paints of different colors at one side may be sequentially used as required. In this method, various color marks can be formed on the surface of individual resin moldings, and also a plurality of marks of different colors may be easily formed on the surface of one resin molding.  
     [0050] In the foregoing embodiment, the film  12  is held parallel to the surface of the resin molding  11 , but other methods as shown in FIG. 5 to FIG. 9 are also possible. As shown in FIG. 5, in which the marking area of the resin molding  21  is relatively wide, if the foregoing marking method of holding a film  22  parallel to the surface of a resin molding  21  is employed, deflection is caused on the surface of the resin molding  21 , and the contact between the film  22  and resin molding  21  is degraded. To prevent this, a marking method as shown in FIG. 6 is utilized. In FIG. 6, a film  23  having a thickness of about 75 microns is used. At a position above the resin molding  21 , the film  23  is deflected and held in a U-form such that the paint  24  applied to one side of film  23  contacts the resin molding. The film  23  is pressed only at the marking position of the resin molding  21 . The film  23  bent in a U-form maintains its U-form, and contacts with the surface of the molding  21 , so that the surface of the paint  23  contacts the surface of the molding  21 .  
     [0051] Alternatively, in FIG. 7, the surface of a resin molding  31  to be marked has a convex circle. In this case, the side of the film  32  to which paint  33  is applied is placed in contact with the resin molding  31 , and by pulling the film  32  from both sides with a proper force while maintaining this state, the film  32  tightly contacts the surface of the circular resin molding  31 .  
     [0052] In FIG. 8, the surface shape of a resin molding  41  is convex. A support stand  42  for positioning and holding the resin molding  41  has a plurality of through-pores  43 . A film  45  is put on the resin molding  41  placed on the support stand  42  so that the side of the film  45  to which paint is applied contacts the resin molding  41 , the covering film  45  is evacuated through the through-pores  43  on the outer circumference of the resin molding  41 . In this state, a laser beam  14  is emitted. In this method, the film  45  tightly contacts the resin molding  41  with a convex surface shape. In this case, it is recommended to use the film having a thickness of about 10 microns to about 25 microns. If the film thickness is less than 10 microns, the film may be torn. If the film thickness exceeds 25 microns, the contact between the film and molding may degrade.  
     [0053] Further, in FIG. 9, the surface of a resin molding  51  has a concave shape. In this case, a paint  53  disposed on a film  52  contains an acrylic resin, which acts as an adhesive having a peelable tacky adhesiveness. On the concave surface of the resin molding  51 , the surface of the film  52  to which the paint  53  is applied contacts the molding  51 . The opposite side of the film  52  is pressed by using an elastic piece  54  in a shape corresponding to the concave shape, and the film  52  and the paint  53  are adhered and held in the concave shape of the resin molding  51 . In this method, the surface of the paint  53  can be securely contacted to the surface of the resin molding  51 , and after finishing the marking, the film  52  can be easily peeled off.  
     [0054] According to the marking methods illustrated in FIG. 6 to FIG. 9, if the surface of the resin molding has a complicated shape such as spherical, convex, or concave shape or has an extremely wide area, the surface of the paint installed at one side of the film can be securely contacted to the surface of the molding. The paint fused by irradiation with laser beam is transferred and marked to the surface of the resin molding with excellent precision.  
     [0055] In the current embodiment, while a laser beam is used, the present invention is not limited to this. Any energy ray having high energy such as electron beam, electron ray or heat ray capable of melting the paint can be used.  
     Exemplary Embodiment 2  
     [0056]FIG. 10 is an sectional view illustrating a marking method in accordance with a second embodiment of the present invention. In FIG. 10, a sublimating paint  63  is disposed on one side of a PET colorless transparent film  62  which is a thermoplastic heat resistant resin. As the energy ray, a YAG layer beam  64  capable of obtaining a short wavelength is used. The YAG laser beam is a beam generated from an apparatus using yttrium-aluminum-garnet material. The other steps to the process are the same as in embodiment 1. In FIG. 10, the YAG laser beam  64  controlled by a deflector  15  completely penetrates through the film  62 , and is concentrated and emitted to the dye  63  and the surface layer of the resin molding  61  beneath it. At this time, the sublimating dye  63  is vaporized, the texture of the surface layer of the resin molding  61  is activated, and the vaporized dye  63  easily permeates into the surface layer of the molding. Thus, the dye  63  is disposed on the molding  61 , and a mark is formed on the surface of the molding  61 .  
     [0057] In this method, the mark is formed by permeating the vaporized dye  63  on the activated surface layer of the resin molding  61 , so that the mark having an excellent wear resistance is formed.  
     [0058] In the embodiment, while the resin molding  61  is flat, it is not limited to this shape. It may have a complicated shape as shown in FIG. 6 to FIG. 9, wherein the same contact is obtained as in embodiment 1, and the same effect as in embodiment 1 is obtained.  
     Exemplary Embodiment 3  
     [0059]FIG. 11 shows an embodiment of a resin molding forming a mark by using the marking method of the present invention. Specifically, FIG. 11 is a partial perspective view of a keyboard as an input device used in an electronic information appliance or the like. In FIG. 11, marks  72  are formed on the surface of key tops  71  which are a plurality of resin moldings of an operation unit. The key tops  71  are made of a thermoplastic resin excellent in processability, and marks  72  are formed on the operation surface (i.e., upper surface). The marks  72  are formed by a method of emitting YAG laser beam by the same method as in embodiment 2, by using a plurality of films coated with sublimating dyes of different colors on one side. Paints of different colors are vaporized and permeate into the surface layer of the key tops  71 , so that the plurality of marks  72  such as characters or patterns are clearly formed on the surface of the key tops  71  at high quality. The marks  72  have an excellent wear resistance.  
     [0060] In another variation, the present invention provides a method of forming a mark having a plurality of colors on the molding. The method comprises the following exemplary steps. Step (a): feeding a plurality of films, each of which has a first surface and a second surface. Step (b): disposing paints on the first surface of each of the plurality of films, wherein each film has a different color paint disposed thereon. Step (c): positioning one of the plurality of films on the surface of the molding so that the paint disposed on the film contacts the surface of the molding, and then emitting an energy ray form the second surface of the film. The energy ray causes the paint disposed on the first surface of the film to be transferred onto the surface of the molding, thereby forming one color on the molding. Step (d): positioning a second of the plurality of films, which has a different color than the first film, on the surface of the molding so that the paint disposed on the film contacts the surface of the molding, and then emitting an energy ray form the second surface of the film. The energy ray causes the paint disposed on the first surface of the film to be transferred onto the surface of the molding, thereby forming a second color on the molding. Step (e): repeating step (d) until all of the desired colors are transferred to the molding.  
     [0061] In the foregoing embodiments, while a colorless transparent film is used, the present invention is not limited to this. A colored translucent film may be used depending on the kind of the laser beam or the color of the applied paint.  
     [0062] Thus, according to the present invention, by the deflection control by NC data, desired characters or patterns can be marked on the surface of the molding. Marks of various colors can be also formed. Moreover, the marks can be formed on the molding at lower cost. Marks having excellent wear resistance can be further formed. In addition, marks of excellent precision can be formed on the surface of the molding having complicated shapes.