Abstract:
An object of the present invention is to provide a process for producing an in-mold decorated molded article, which can eliminate the need for deburring after molding and the need for an extra allowance of the molded article. The process includes: clamping a first mold ( 1 ) and a second mold ( 2 ) to hold a decorative film ( 207 ) between the molds; cutting a transfer layer ( 302 ) of the decorative film ( 207 ) in the molds; injecting resin ( 5 ) into the cavity of the mold; cooling the resin ( 5 ); and opening the molds to remove the in-mold decorated molded article on which the transfer layer ( 302 ) is disposed.

Description:
TECHNICAL FIELD 
     The present invention relates to a process for producing an in-mold decorated molded article, in which a decorative film is inserted into molds and then resin is injected into the molds to perform injection molding, thereby decoratively transferring the pattern of a transfer layer provided in the decorative film onto a surface of the molded article. 
     BACKGROUND ART 
     Processes for decorating a surface of a resin molded article include insert molding and in-mold molding. 
     In insert molding, as illustrated in  FIG. 12(   a ), a decorative film  200  cut in a predetermined shape is set in a cavity  101  of a mold  100 . Then, as illustrated in  FIG. 12(   b ), resin  5  is injected into the cavity  101  from an injection hole  103   a . The resin  5  is cured and then is removed from the opened mold  100 , completing a molded article  300  having a surface decorated with the decorative film  200  as illustrated in  FIG. 12(   c ). The decorative film  200  is formed by stacking a UV hard coating layer  210 , an anchor layer  211 , a printing layer  210 , and an adhesive layer  213 . 
     In insert molding, it is difficult to locate the decorative film  200  in the mold  100 . Thus, it is difficult to precisely locate the decorative film  200  in the molded article  300 . As illustrated in  FIG. 13(   a ), an end of the decorative film  200  embedded into the article is fully covered with the resin  5  and thus the end of the decorative film  200  in a finished state is not exposed. The decorative film  200  appears to be firmly joined to the resin  5  but actually, the decorative film  200  easily peels off from the resin  5 .  FIG. 13(   b ) is a cross-sectional view taken along the arrows A-A of  FIG. 13(   a ), illustrating a state of the end of the decorative film  200 . 
     In a conventional process of in-mold molding, a long decorative film  207  in  FIG. 9  is used instead of the cut decorative film  200  that is set in the mold  100  in insert molding. 
     In in-mold molding, the decorative film is easily located and the productivity is higher than that of insert molding. An in-mold decorated molded article removed from an opened mold may have so-called “foil flash” that occurs when a transfer layer from the decorative film remains around the article. Foil flash is manually removed after the removal of the molded article or is removed with a special tool after molding. 
     The decorative film  207  used in in-mold molding includes a PET base film  208  that continuously supplies the decorative film  207  into the mold, a release layer  209  formed on the base film  208 , a UV hard coating layer  210  that is located on the outermost surface to protect the molded article from scratches, dust, etc. after being transferred onto the molded article, an anchor layer  211  formed on the UV hard coating layer  210 , a printing layer  212  formed on the anchor layer  211  to transfer designs such as patterns and figures onto the molded article, and an adhesive layer  213  that is formed on the printing layer  212  and adheres to resin. 
     In the decorative film  207 , a transfer layer  302  to be transferred onto a surface of the molded article is composed of the adhesive layer  213 , the printing layer  212 , the anchor layer  211 , and the UV hard coating layer  210 , and a carrier layer  301  not to be transferred onto the molded article is composed of the release layer  209  and the base film  208 . 
       FIG. 10  illustrates in-mold molding using the decorative film  207  according to patent literature 1. The mold includes a stationary mold  103  and a movable mold  104 . 
     In step (a), the decorative film  207  is inserted between the stationary mold  103  and the movable mold  104 . At this point, the decorative film  207  is supplied so as to locate the base film  208  near a cavity  104   b  of the movable mold  104 . 
     In step (b), the movable mold  104  is moved to clamp the decorative film  207 . 
     In step (c), resin  111  is injected from a cavity  103   a  of the stationary mold  103  to the adhesive layer  213  of the decorative film  207 , filling the cavities  103   a  and  104   b  in the molds with the resin  111 . 
     In step (d), a molded article  121  is cooled to a predetermined temperature after the completion of the injection of the resin  111 . 
     In step (e), the movable mold  104  is moved and opened. In the opening of the mold, the carrier layer  301  of the decorative film  207  is peeled off from the molded article  121  and the transfer layer  302  of the decorative film  207  is transferred onto the molded article  121 . Thus, the outermost surface of the molded article  121  is covered with the UV hard coating layer  210 . After that, protruding pins  7  on the stationary mold  103  are pressed to remove the molded article  121  from the mold. The molded article  121  includes a part serving as an end item  121   a  and a sprue  121   b  that is an unnecessary part of the item. 
     In such a process of in-mold molding, the transfer layer  302  can be located in the molds with higher accuracy than in insert molding. However, when the molded article  121  is peeled off from the decorative film  207 , a part of the transfer layer  302  may not be finely peeled off around the molded article  121 , so that the part having not been transferred onto the molded article  121  may be peeled off and remain on the molded article  121 , causing foil flash  303  to occur (see an enlarged view in  FIG. 10(   e )). 
     In the production of the in-mold decorated molded article, in the absence of an extra machine allowance other than the sprue  121   b , the formed foil flash  303  is manually cut off from the molded article  121  with a box cutter or the like in a downstream process after molding. 
     As illustrated in  FIG. 11(   a ), an extra machine allowance may be provided outside the required dimensions of the molded article. In this case, a cutting step is necessary for separating the molded article  121  into the end item  121   a  and the unnecessary sprues  121   b.    
     In the cutting step of  FIG. 11(   b ), the molded article  121  is cut with cutting tools  11 . The cutting tool  11  includes cutters  11   a  for cutting and a base  11   b  on which the cutters  11   a  are fixed. The cutters  11   a  vertically hold predetermined inclined faces  12   c  of the molded article  121  to cut off the sprues  121   b  from the molded article  121 , obtaining the end item  121   a.    
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Laid-Open No. 2001-260168 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the process of in-mold molding, the decorative film in the mold can be located with higher accuracy than in insert molding. However, as has been discussed, the foil flash  303  may occur. 
     In the production of the in-mold decorated molded article, in the absence of an extra machine allowance other than the sprue  121   b , the formed foil flash  303  is manually cut off from the molded article  121  with a box cutter or the like in a downstream process after molding. 
     As illustrated in  FIG. 11(   a ), an extra machine allowance may be provided outside the required dimensions of the molded article. In this case, a cutting step is necessary for separating the molded article  121  into the end item  121   a  and the unnecessary sprues  121   b.    
     In the cutting step of  FIG. 11(   b ), the molded article  121  is cut with the cutting tools  11 . The cutting tool  11  includes the cutters  11   a  and the base  11   b  on which the cutters  11   a  are fixed. The cutters  11   a  vertically hold the predetermined inclined faces  12   c  of the molded article  121  to cut off the sprues  121   b  from the molded article  121 , obtaining the end item  121   a.    
     In the conventional process of in-mold molding, the removal of the foil flash  303  requires a downstream process to remove foil flash from the molded article after molding. Moreover, in the case where it is difficult to remove only the foil flash  303 , an extra allowance is provided outside the dimensions of the molded article to enable cutting and deburring around the molded article. Hence, the manufacturing cost increases because of the cost of after treatment and a material loss. 
     An object of the present invention is to provide a process for producing an in-mold decorated molded article, which can eliminate the need for deburring after molding and the need for an extra allowance of the molded article. 
     Solution to Problem 
     A process for producing an in-mold decorated molded article according to the present invention, includes: locating a decorative film between a first mold and a second mold, the decorative film having a carrier layer and a transfer layer; cutting the transfer layer of the decorative film instead of the carrier layer in a state in which the decorative film is held between the first mold and the second mold by clamping the first mold and the second mold; injecting resin into a cavity formed by clamping the first mold and the second mold, cooling the resin, and then opening the first mold and the second mold to peel the transfer layer from the carrier layer of the decorative film; and removing the in-mold decorated molded article having the transfer layer on the surface of the resin. 
     The process further includes moving the nest of the second mold to the first mold to cut the transfer layer of the decorative film. 
     The process further includes sliding the cut surface of the transfer layer on the inner wall surface of the first mold when moving the nest of the second mold after clamping the first mold and the second mold and injecting the resin. 
     The process further includes sliding the cut surface of the transfer layer on a mirror surface formed on the inner wall surface of the first mold when moving the nest of the second mold after clamping the first mold and the second mold and injecting the resin. 
     The relationship between the edge of the nest on the contact surface of the decorative film and the inner edge of the first mold on the contact surface of the decorative film is expressed as R&gt;r where R is a radius for chamfering on the edge of the nest and r is a radius for chamfering on the inner edge of the first mold, and at least one of the edge of the nest and the inner edge of the first mold is chamfered. 
     The process further includes, when the resin is injected into the cavity formed by clamping the first mold and the second mold, injecting the resin into a recess formed inside the first mold so as to be aligned with the position of the cut surface of the transfer layer, and injecting the resin to the cut surface of the transfer layer so as to cover the cut surface with the resin. 
     An in-mold decorated molded article according to the present invention is an in-mold decorated molded article of resin, the molded article including a decorative film as a surface layer, wherein the decorative film includes a transfer layer having a cut surface, the cut surface being exposed on the end face of the in-mold decorated molded article, and the resin fills a crack on the cut surface of the transfer layer. 
     Advantageous Effects of Invention 
     With this configuration, the transfer layer of the decorative film is cut before molding. Thus, when the in-mold decorated molded article is peeled off from the carrier layer of the decorative film after molding, foil flash does not occur because of the cutting of the transfer layer, achieving an in-mold decorated molded article without the need for removing foil flash on the end face of the molded article. 
     Moreover, the transfer layer of the decorative film can be cut in the molds before molding, eliminating the need for an extra allowance of the molded article. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates cross-sectional views of molds, showing steps S 1  to S 3  of a process for producing an in-mold decorated molded article according to a first embodiment of the present invention. 
         FIG. 2  illustrates a cross-sectional view of the molds and an enlarged view of a principal part, showing step S 4  of the first embodiment. 
         FIG. 3  illustrates a cross-sectional view of the molds and an enlarged view of a principal part, showing step S 5  of the first embodiment. 
         FIG. 4  illustrates cross-sectional views of the molds, showing steps S 6  to S 9  according to the first embodiment. 
         FIG. 5  illustrates a cross-sectional view of molds and an enlarge view of a principal part according to a second embodiment of the present invention. 
         FIG. 6  is an enlarged view illustrating a principal part of molds according to a third embodiment of the present invention. 
         FIG. 7  is an enlarged view illustrating a principal part of molds according to a fourth embodiment of the present invention. 
         FIG. 8(   a ) is an enlarged view illustrating the end face of the in-mold decorated molded article according to the foregoing embodiments, and  FIG. 8(   b ) is a cross-sectional view taken along the arrows B-B of  FIG. 8(   a ). 
         FIG. 9  is a cross-sectional view illustrating a decorative film for in-mold molding. 
         FIG. 10  illustrates a process drawing of a conventional process for in-mold molding. 
         FIG. 11  illustrates explanatory drawings of steps and tools for deburring on the ends of a conventional in-mold decorated molded article. 
         FIG. 12  is a process drawing illustrating a conventional process for insert molding. 
         FIG. 13(   a ) is an enlarged view illustrating a decorative film on the end face of a conventional insert molded article, and  FIG. 13(   b ) is a cross-sectional view taken along the arrows A-A of  FIG. 13(   a ). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A process for producing an in-mold decorated molded article of the present invention will be described below in accordance with specific embodiments. 
     (First Embodiment) 
       FIGS. 1 to 4  are process drawings illustrating a process for producing an in-mold decorated molded article according to a first embodiment of the present invention. A decorative film  207  is identical in structure to that of  FIG. 9 . 
     The mold of the first embodiment includes a stationary mold  1  serving as a first mold and a movable mold  2  serving as a second mold. The movable mold  2  has a divided structure of a movable mold body  2   b  and a nest  2   a  disposed in the movable mold body  2   b  so as to move relative to the movable mold body  2   b . The nest  2   a  is separately movable. 
     In step S 1  of  FIG. 1 , the decorative film  207  drawn from a winding member is set on a film feeder  4  such that an adhesive layer  213  faces an injection hole  103   a  of the stationary mold  1 . The film feeder  4  has the function of feeding the decorative film  207  to the movable mold  2  and the function of positioning control of the patterns and figures of the decorative film  207  in the movable mold  2 . 
     In step S 2  of  FIG. 1 , the decorative film  207  is sucked by suction holes  3  formed on the nest  2   a  of the movable mold  2  to fix the position of the decorative film  207  in the movable mold  2 , and then the decorative film  207  is fixed by a clamping mechanism (not shown). In other words, the decorative film  207  is sucked and held along the shape of the mold surface of the movable mold  2 . 
     In step S 3  of  FIG. 1 , the movable mold  2  is closed. Thus, the decorative film  207  is held between the stationary mold  1  and the movable mold body  2   b.    
     In step S 4 , as illustrated in (S 4 - 1 ) of  FIG. 2 , the decorative film  207  is partially cut in the mold. (S 4 - 2 ) in  FIG. 2  is an enlarged view of principal part A of (S 4 - 1 ) in  FIG. 2 . The nest  2   a  is moved to the stationary mold  1  by a movable mechanism  2   c , so that the decorative film  207  has a shearing force on the boundary between a part held by the stationary mold  1  and the movable mold body  2   b  and a part driven by the nest  2   a  to the stationary mold  1 , thereby cutting a transfer layer  302 . At this point, the end of the cut transfer layer  302  has small gaps, asperities, cracks (fractures), and so on. The movable mechanism  2   c  is movable in a minimum distance range allowing cutting of a UV hard coating layer  210 , an anchor layer  211 , a printing layer  212 , and an adhesive layer  213  that constitute the transfer layer to be transferred to the molded article. The movable mechanism  2   c  is movable in a range that does not cut a base film  208 , so that only the transfer layer  302  of the decorative film  207  is cut. 
     To be specific, the movable mechanism  2   c  is moved to a distance shorter than the thickness of the base film  208  and longer than the thickest portion of the transfer layer  302 . The base film  208  is 20 μm to 50 μm in thickness, and the transfer layer  302  is 2 μm or 40 μm in thickness. In this case, the base film  208  is a PET film having a thickness of 38 μm and the thickest portion of the transfer layer  302  is 15 μm in thickness. 
     In step S 5 , as illustrated in (S 5 - 1 ) of  FIG. 3 , the injection of resin  5  is started from the injection hole  103   a  of the stationary mold  1  after the cutting of the UV hard coating layer, the anchor layer, the printing layer, and the adhesive layer that correspond to the transfer layer  302  of the decorative film  207  to be transferred to the molded article. 
     At this point, the heat of the resin  5  sufficiently propagates through the cut transfer layer  302  of the decorative film  207 , allowing the decorative film  207  to expand in principal part B 1  of (S 5 - 1 ) in  FIG. 3  as illustrated in (S 5 - 2 ) of  FIG. 3  and a partial enlarged view of (S 5 - 3 ) in  FIG. 3 . (S 5 - 3 ) illustrates principal part B 2  of (S 5 - 2 ) in  FIG. 3 . Thus, the rough cut surface of the transfer layer  302  is strongly pressed to the inner wall surface of the stationary mold  1 . As illustrated in a partial enlarged view of (S 5 - 4 ) in  FIG. 3 , the cut surface of the transfer layer  302  is strongly pressed to the inner wall surface of the stationary mold  1  so as to round the outer periphery of the transfer layer  302 , forming a smooth cut surface. In other words, foil flash is less likely to occur than in the conventional configuration. 
     As illustrated in  FIG. 8(   a ), the cut surface of the transfer layer  302  of the decorative film  207  is exposed on the end face of the in-mold decorated molded article, and small gaps of about several tens pm, asperities, and cracks (fractures)  400  appear on the cut surface of the transfer layer  302  of the decorative film  207 . As illustrated in  FIG. 8(   b ), the molding resin  5  enters the gaps, asperities, and cracks (fractures)  400  between the adhesive layer  213  and the printing layer  210 , between the printing layer  210  and the anchor layer  211 , and between the anchor layer  211  and the UV hard coating layer  210 , leading to a higher adhesion strength between the outer periphery of the transfer layer  302  and the molding resin after molding. Thus, even in the case where the end of the transfer layer  302  is exposed in a finished state, the decorative film does not peel off unlike in insert molding of  FIGS. 13(   a ) and  13 ( b ). 
     In insert molding, the decorative film  200  having an unexposed end in a finished state easily peels off. This is because the decorative film  200  is efficiently cut and separated using a cutter having extremely high cuttability and thus the end face of the decorative film  200  is a smooth cut surface free from the small gaps, asperities, and cracks (fractures)  400  illustrated in  FIG. 8(   b ), leading to a lower adhesion strength with the molding resin. 
     As illustrated in  FIG. 4 , the resin  5  is fully injected into the mold in step S 6 . In this state, the movable mechanism  2   c  having separately moved the nest  2   a  of the movable mold  2  is pressed back to the original position by the pressure of the resin  5  injected into the mold. At this point, the transfer layer of the decorative film is in sliding contact with the wall surface of the stationary mold  1  and the end of the transfer layer is finished to a smoother surface by sliding friction, thereby suppressing the occurrence of foil flash. 
     In step S 7  of  FIG. 4 , after the resin  5  is sufficiently cooled in the mold, the movable mold  2  is moved and opened to peel off a carrier layer  301  and the transfer layer  302  of the decorative film  207 , and the removal of an in-mold decorated molded article  6  from the mold is prepared. The UV hard coating layer, the anchor layer, the printing layer, and the adhesive layer have been transferred onto the surface of the resin  5 . In the present embodiment, the transfer layer  302  is cut beforehand in step S 4  and the cut surface of the transfer layer  302  is coated with the resin  5 . In this state, the transfer layer  302  is peeled off from the carrier layer  301 , hardly causing foil flash. 
     In step S 8  of  FIG. 4 , protruding pins  7  of the stationary mold  1  are moved to remove the in-mold decorated molded article  6  from the mold. 
     In step S 9  of  FIG. 4 , for the subsequent molding, the suction of the nest  2   a  of the movable mold  2  to the base film by the suction holes  3  is stopped, the base film serving as the carrier of the decorative film  207 , and the suction of the movable mold  2  to the release layer is stopped. The film feeder  4  feeds the decorative film  207  to a certain position where the transfer layer has printed patterns and figures used for the subsequent molding. 
     (Second Embodiment) 
       FIG. 5  shows a second embodiment of the present invention. 
     In step S 5  of the first embodiment, the nest  2   a  of the movable mold  2  is moved to the stationary mold  1  by the movable mechanism  2   c  to cut the transfer layer  302  (the UV hard coating layer, the anchor layer, the printing layer, the adhesive layer) of the decorative film  207 , and then the cut surface of the transfer layer  302  is slid on the inner wall surface of the stationary mold  1  by the expansion of the transfer layer  302  with heat from the injected resin  5  and the lowering of the nest  2   a  of the movable mechanism  2   c  returning to the original position, thereby rounding the cut surfaces of the adhesive layer  213 , the printing layer  212 , the anchor layer  211 , and the UV hard coating layer  210  that constitute the transfer layer  302 . 
     The second embodiment is different, as illustrated in (S 5 - 1 ) of  FIG. 5 , from the first embodiment in that a mirror surface  8  is formed on a part of the inner wall of a stationary mold  1  so as to extend around the opening of the stationary mold  1 . The mirror surface  8  is smoother than other parts of the inner surface of the stationary mold  1 . 
     Specifically, after a transfer layer  302  of a decorative film  207  is cut in step S 4 , as illustrated in (S 5 - 2 ) that is an enlarged view of principal part B 1  of (S 5 - 1 ) in  FIGS. 5  and (S 5 - 3 ) that is an enlarged view of principal part B 2  of (S 5 - 2 ) in  FIG. 5 , a rough surface on the end of the cut transfer layer  302  of the decorative film  207  is pressed to the mirror surface  8 , and then a nest  2   a  is moved by a movable mechanism  2   c . Thus, as illustrated in (S 5 - 4 ) of  FIG. 5 , the cut surface of the transfer layer  302  is rounded and mirror-finished. After that, resin  5  is injected, achieving an in-mold decorated molded article with little foil flash and a mirror-finished end. 
     In this configuration, the nest  2   a  is preferably moved up and down repeatedly by the movable mechanism  2   c  any number of times so as to mirror-finish the end of the transfer layer  302 . 
     (Third Embodiment) 
       FIG. 6  shows a third embodiment of the present invention. 
     In the first embodiment, the cut surface of the transfer layer  302  is slid and rounded on the inner wall of the stationary mold  1 . The third embodiment is, as illustrated in  FIG. 6 , different from the first embodiment in that a recess  9  is formed on the inner wall of a stationary mold  1  so as to extend around the inner wall of the stationary mold  1 . 
     (S 4 - 1 ) in  FIG. 6  is a partial enlarged view illustrating a state in which a transfer layer  302  (a UV hard coating layer, an anchor layer, a printing layer, an adhesive layer) of a decorative film  207  is cut by moving a movable mechanism  2   c  to the stationary mold  1  before molding. 
     The recess  9  is provided in the stationary mold  1  so as to be aligned with the cut surface of the transfer layer  302  of the decorative film  207  in the stationary mold  1 . Thus, as illustrated in a partial enlarged view in (S 4 - 2 ) of  FIG. 6 , resin  5  injected into the recess  9  in step S 6  covers the cut surface of the cut transfer layer  302  of the decorative film  207 . 
     Since the resin  5  covers the cut surface, an in-mold decorated molded article can have higher adhesion strength on the cut surface of the transfer layer  302  and between the layers of the transfer layer  302  than in the first embodiment. When the molded article is removed from the mold, foil flash hardly occurs because the transfer layer has been cut before the resin is injected into the mold and the transfer layer is peeled off from a carrier layer while the end of the transfer layer is coated with the resin. 
     The recess  9  has a dimensional tolerance allowing the molded article to be easily removed by protruding pins  7  in step S 8 , so that the recess  9  does not interfere with the removal of the molded article. 
     (Fourth Embodiment) 
       FIG. 7  shows a fourth embodiment of the present invention. 
     As has been discussed in the first embodiment, only the transfer layer  302  of the decorative film  207  is cut in step S 4 , the decorative film  207  including the carrier layer  301  and the transfer layer  302 . The fourth embodiment will discuss the relationship between a radius R for chamfering on the edge of a nest  2   a  of a movable mold  2  and a radius r for chamfering on the inner edge of a stationary mold  1 , the relationship enabling smooth cutting of a transfer layer  302  without cutting a carrier layer  301  even when the carrier layer  301  has an extremely small thickness. 
     As illustrated in  FIG. 7 , in the case where the carrier layer  301  in a decorative film  207  is extremely thin, the radius r for chamfering on the inner edge of the stationary mold  1  is set on the edge so as to facilitate cutting of the transfer layer  302  of the decorative film  207 . The radius R for chamfering on the edge of the nest  2   a  is set to R&gt;r, so that the carrier layer  301  is unlikely to be cut. Specifically, the value of the radius R for chamfering on the edge of the nest  2   a  was set to 0.05 mm as the decorative film having a thickness of 45 μm. At this point, r was 0.02 mm. This allowed only the transfer layer  302  of the decorative film  207  to be smoothly cut in the mold before molding even in the case where the carrier layer  301  has an extremely small thickness. 
     In this case, both of the edge of the nest  2   a  of the movable mold  2  and the inner edge of the stationary mold  1  are chamfered. The inner edge of the stationary mold  1  may form a right angle without being chamfered and only the nest  2   a  of the movable mold  2  may have a chamfered edge. This configuration was also found to be more effective than the conventional configuration. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to the production of a variety of in-mold decorated molded articles, e.g., exterior components for household appliances and exterior components for vehicles.