JP2006289794A - Mold for in-mold coating molding and in-mold coating molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-mold coating molding means constituted so as to enable multi-impression molding, capable of injecting coating in a cavity through a runner even if a cavity has a rising surface part and capable of coating a resin molded product with a coating film having a uniform thickness. <P>SOLUTION: A mold 10 comprises the fixed mold part 3 and the movable mold part 4. A plurality of cavities 5 and 6 being the molding spaces of the resin molded product 14, runners 7 and 8 for injecting a molten resin in a plurality of the cavities 5 and 6 and a coating material injection passage for injecting a coating into a plurality of the cavities 5 and 6 are formed to the mold 10 by the fixed mold part 3 and the movable mold part 4. The mold 10 is characterized in that the runners 7 and 8 are respectively connected to a plurality of the cavities 5 and 6 and a recessed part 17 is formed to the surface excepting the coating material flowing surface of the surfaces forming the runners 7 and 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, after molding a plurality of resin molded products in the cavity of the mold, the resin molded products are coated (painted) with a paint without taking out the resin molded products from the mold. The present invention relates to a coating molding method and a mold for in-mold coating molding used therein.

  Generally, in order to improve the decorativeness of the resin molded product, a means for coating the surface by painting and decorating is employed. In recent years, in-mold coating molding methods (in-mold molding) in which molding using a resin and surface coating of the obtained resin molded product are performed in the same mold for the purpose of omitting the process by painting. This is called a coating method.

  In-mold coating molding method involves injecting and filling resin into a clamped mold, solidifying by cooling to obtain a resin molded product, and then holding the resin molded product while holding the resin molded product in the mold. Slightly open and inject the coating material (coating material) into the gap formed between the resin molded product and the cavity forming surface. Then, the mold is clamped again and the coating material injected on the surface of the resin molded product. It is a method of obtaining a resin molded product whose surface is coated with a coating film by uniformly spreading and curing the paint.

  According to such an in-mold coating molding method, since the molding using the resin and the coating to the obtained resin molded product are performed in the same mold, the process is omitted and the process is suspended. It is possible to obtain a high-quality product at a low cost with almost no problems such as dust adhering to the uncured coating film resulting in a defective product. In particular, the use of the in-mold coating forming method is suitable for many parts such as automobile parts, such as bumpers, door mirror covers, and fenders, which require high quality in appearance.

In addition, Patent Literature 1 and Patent Literature 2 are cited as prior literature on the in-mold coating molding method. Patent Document 1 proposes a means that can effectively prevent leakage of molten resin from the mold parting surface of the mold. Further, Patent Document 2 discloses a means capable of preventing paint leakage over a long period of time by providing a groove over the entire circumference of the auxiliary cavity extending in the opening / closing direction of the mold.
JP-A-9-52257 JP 2003-191286 A

  However, in order to mold a plurality of resin molded products at once (also referred to as a large number), an in-mold coating molding method is performed using a mold having a plurality of cavities as molding spaces for the resin molded products. In some cases, it is impossible to satisfactorily coat the surface of a part of the rising surface portion of the resin molded product molded at the rising surface portion of the cavity. The in-mold coating method is a means that can eliminate the process and obtain a product at a low cost. However, if the quality is not stable, the yield is lowered when high quality is required for the appearance. This leads to an increase in product costs. On the other hand, in order to improve production efficiency in the manufacture of resin molded products, it is assumed that it is further desired to take a large number in the future. Therefore, there has been a demand for an in-mold coating forming means that can apply a high-quality coating more stably even when a large number are taken.

  On the other hand, as a result of repeated research, when the mold is opened slightly, there is a case where a uniform gap does not occur between the resin molded product and the cavity forming surface of the mold at the rising surface of the cavity. It was thought that this led to the quality deterioration concerning coating. This problem will be described with reference to FIGS.

  5-7 is a figure which shows an example of the conventional metal mold | die used for multi-cavity in-mold coating molding. 5 is a cross-sectional view showing the parting line, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, that is, a parting surface of the movable mold part, and FIG. 7 is a diagram when the mold is opened slightly. 5 is an enlarged cross-sectional view of an E portion surrounded by an ellipse in FIG. 5, that is, a standing surface portion of a cavity. The illustrated mold 50 is composed of a fixed mold part 53 and a movable mold part 54, and two cavities 55 and 56 are formed by these mold split surfaces. A sprue 59 for injecting molten resin into the cavities 55 and 56 is formed in the fixed mold part 53, and the sprue 59 and the cavity 55 are formed by the mold dividing surfaces of the fixed mold part 53 and the movable mold part 54. , And a runner 58 that connects the sprue 59 and the cavity 56 are formed. The runners 57 and 58 diverge from the spru 59 as flow paths of the molten resin and are connected almost vertically to the cavities 55 and 56, respectively. The runners 57 and 58 also communicate with each other. Further, a coating material injection path 51 for injecting paint into the cavities 55 and 56 from the coating material injection port 61 using the injection machine 52 is provided through the runners 57 and 58.

  In the mold 50 for in-mold coating that can be obtained in large numbers, the fixed mold portion 53 and the movable mold portion 54 are clamped, and molten resin is injected from the spru 59 into the cavity 55 through the runner 57. When filled, cooled and solidified, the molten resin contracts with cooling and solidification and is molded as a resin molded product 64 without opening the mold 50 while the mold is clamped (see FIG. 7). Due to this contraction, a tensile force acts in the longitudinal direction (in the direction of the arrow in FIG. 7) in the resin molded product main body portion 64 a formed by the main body portion 66 of the cavity 55 and the molded body 65 formed by the runner 57. The resin molded product standing surface portion 64b molded by the standing surface portion 62 (see FIG. 7) is pulled and deformed from both directions. Therefore, even if the movable mold part 54 is slightly separated from the fixed mold part 53 and the mold 50 is opened, the resin molded product standing surface part 64 b formed by the standing surface part 62 is fixed on the body part 66 side of the cavity 55. The gap 63 is formed in close contact with the mold 53 while being separated from the movable mold 54. On the runner 57 side, the resin molded product standing surface portion 64b is in close contact with the movable mold portion 54, while being separated from the fixed mold portion 53. Further, the molded body 65 in the runner 57 is moved to the movable mold portion 54. (F portion in FIG. 7). Therefore, in the state shown in FIG. 7, even if the coating material is injected from the coating material injection port 61 using the injection device 52, the coating material flow path is not formed in the runner 57 and the standing surface portion 62, and the coating material is removed from the cavity 55. It cannot be introduced inside. Such a phenomenon can occur on the cavity 56 (runner 58) side as well.

  When the mold 50 is further opened from the state shown in FIG. 7, a gap is formed in the runner 57 between the molded body 65 and the movable mold part 54, and a paint flow path is secured. However, the gap between the resin molded product standing surface portion 64b and the movable mold portion 54 in the similarly formed standing surface portion 62 is not uniform and does not have the same size as the gap 63. It was inferred that the thickness of the coating film formed on the molded product 64 was not uniform, and the quality of the coating was reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an in-mold coating forming means that solves the conventional problems. More specifically, a large number of pieces can be taken, and even if there are standing surfaces in the cavity, the paint can be injected into the cavity through the runner, and a resin molded product can be formed with a uniform film thickness. It is an object to provide an in-mold coating molding means that can be coated. The present invention achieves the above object by providing the means described below.

  That is, according to the present invention, first, a fixed mold part and a movable mold part are configured, and the fixed mold part and the movable mold part are used to form a plurality of cavities that are molding spaces of the resin molded product, and a plurality of them. A mold for in-mold coating molding in which a runner for injecting molten resin into the cavities and a coating material injection path for injecting coating materials into the plurality of cavities are formed, A mold in which a runner is connected to each of a plurality of cavities, and at least one recess is formed on a surface of each of the surfaces forming the runners connected to the plurality of cavities except for a surface through which a covering material flows. An inner coating mold is provided.

  In the present specification, the coating material refers to a fluid coating material, and is usually a paint. The coating material injection path is a flow path of the coating material from the coating material injection port (opening through which the coating material is injected from the outside of the mold) to the runner.

  In the in-mold coating mold according to the present invention, the recess may be formed on any of the surfaces on which the runner is formed, and the surface on which the coating material flows is a flow for injecting the coating material into the cavity. It is excluded because it needs to be secured as a road. In the mold for in-mold coating molding according to the present invention, for example, when the coating material is injected into the gap formed by the movable mold part being separated from the resin molded product and the fixed mold part, the runner is used. Of the surfaces to be formed, the surface through which the coating material flows is a surface that is substantially perpendicular to the opening and closing direction of the mold among the surfaces (inner surface) where the movable mold part forms the runner. Of the surface (inner surface) on which the movable mold part forms a runner, the surface is substantially parallel to the opening and closing direction of the mold, and the surface on which the fixed mold part forms the runner (inner surface).

  Further, in the mold for in-mold coating molding according to the present invention, the runner is connected to the cavity, but the runner that is a space formed by the fixed mold part and the movable mold part is connected to the cavity. Such an angle (the angle formed by both) is not particularly limited. In the in-mold coating mold according to the present invention, the runner is formed in a direction substantially perpendicular to the opening and closing direction of the mold by the mold splitting surface of the fixed mold part and the mold splitting face of the movable mold part. The aspect connected to the standing surface part (part formed in the surface of the mold in the opening and closing direction) of the cavity is included.

  In the in-mold coating mold according to the present invention, the number, shape, depth, and other aspects of the recesses are not limited, but the recesses are surfaces on which the covering material flows among the surfaces forming the runners. It is preferable that it is formed in a step shape on the surface excluding.

  Moreover, it is preferable that a plurality of recesses are formed.

  Furthermore, it is preferable that the recess is formed in the vicinity of the cavity. When a plurality of recesses are formed, it is desirable that at least one of the recesses is formed in the vicinity of the cavity. For example, when two concave portions are formed, it is preferable that one of them is formed in a step shape near the cavity, and the other one is formed as a concave portion that is smoothly recessed at a position away from the cavity. (The same applies to the in-mold coating forming method according to the present invention described later).

  Next, according to the present invention, each mold connected to a plurality of cavities is inserted into a plurality of cavities formed by the mold using a mold composed of a fixed mold part and a movable mold part. After filling the molten resin through the runner and solidifying the molten resin to obtain a plurality of resin molded products, the movable mold with respect to the fixed mold part while holding the resin molded products in each cavity The part is separated and the mold is opened slightly, and the coating material is injected through the runner into the gap formed between the surface of the movable mold part or the fixed mold part forming the cavity and the resin molded product. And covering the surface of the resin molded product in the mold, at least on the surface of the mold that forms the respective runners connected to the plurality of cavities except the surface through which the coating material flows. Forming one recess and solidifying the molten resin in the recess By delaying, suppressing type coating forming method a tensile force to the resin molded article to be molded in the cavity is provided.

  To delay the solidification of the molten resin in the recess means that at least the solidification of the molten resin in the recess of the runner is delayed from the other runner portions. It is more preferable that solidification of the molten resin in the recesses of the runner including the cavity portion solidify most late. The molten resin shrinks as it cools and solidifies, and in the molded body formed by the runner, even if a tensile force is applied in the longitudinal direction first from where it solidifies, the solidification of the molten resin in the recess is delayed, so the tensile force is The rising surface portion of the resin molded product that is absorbed and molded at the rising surface portion of the cavity is not deformed.

  In the in-mold coating molding method according to the present invention, the number, shape, depth, and other aspects of the recesses are not limited, but the recesses exclude the surface on which the covering material flows out of the surfaces forming the runner. It is preferable that the surface is formed in a step shape.

  Moreover, it is preferable that a plurality of recesses are formed.

  Furthermore, it is preferable that the recess is formed in the vicinity of the cavity.

  In the mold for in-mold coating molding according to the present invention, at least one recess is formed on a surface excluding a surface through which a coating material flows among surfaces forming respective runners connected to a plurality of cavities, By delaying the solidification of the molten resin in the concave portion, it is possible to suppress the tensile force with respect to the resin molded product molded in the cavity. That is, the in-mold coating molding die according to the present invention is suitably used for the implementation of the in-mold coating molding method according to the present invention.

  Since the pulling force on the resin molded product molded in the cavity is suppressed, the resin molded product standing surface part molded at the cavity standing surface part is not deformed due to condensation accompanying molding, and the resin molded product standing surface part is a mold. A uniform gap can be formed with respect to the movable mold part or the fixed mold part on both the main body side and the runner side of the cavity while being held inside. Then, for example, the coating material can be introduced from the coating material injection port into the cavity through the runner (more strictly, to the gap between the cavity forming surface and the resin molded product), and the coating material with a uniform thickness can be introduced. It is possible to coat the resin molded product with a film. Therefore, a high-quality resin molded product can be produced with high efficiency.

  In a preferred embodiment of the mold for in-mold coating molding according to the present invention, the concave portion is formed in a step shape. When the concave portion is in such a form, when the molten resin in the concave portion of the runner is solidified, the molded body molded in the concave portion of the runner is fitted into the concave portion as a convex portion, and the molded body molded in the entire runner Even if a shrinkage occurs due to molding of the portion other than the recess of the runner and a tensile force acts in the longitudinal direction, the resin molded product standing surface portion formed by the cavity's standing surface portion resists the pulling force. To prevent deformation.

  FIG. 1, FIG. 2, and FIG. 10 are views showing an embodiment of an in-mold coating mold of the present invention used in a multi-cavity in-mold coating forming method according to the present invention. FIG. 1 is a sectional view showing a parting line, and FIG. 2 is an enlarged sectional view of a portion B surrounded by an ellipse in FIG. 1, that is, a rising surface portion of a cavity. It is the same mode. FIG. 10 is a view showing an XX cross section in FIG. 1, that is, a parting surface of the movable mold part. A mold 10 shown in the figure is composed of a fixed mold part 3 and a movable mold part 4 in the same manner as a conventional mold, and two cavities 5 and 6 are formed by these split surfaces. is there. In the present specification, the mold dividing surface means a dividing surface as a mold, and indicates a surface where the fixed mold part and the movable mold part face each other. The standing surface portion of the cavity refers to a portion of the cavity formed by the surface in the mold opening / closing direction, and is not limited, but generally, the longitudinal direction of the cavity corresponds to the mold opening / closing direction. The portion corresponds to the standing surface portion. A part of the resin molded product formed at the standing surface portion of the cavity is called a resin molded product standing surface portion. Moreover, although it expresses with a main-body part with respect to a standing surface part, it is a word which points out parts other than a standing surface part.

  The mold 10 is a component of a molding apparatus used in the in-mold coating molding method. For example, in a molding apparatus including a mold clamping device, a mold device incorporated in the mold clamping device, an injection device, and a control device. This constitutes a mold apparatus. The mold 10 is incorporated in a mold clamping device (not shown), and opens and closes when the movable mold part 4 is separated from the fixed mold part 3. A sprue 9 for injecting molten resin into the cavities 5 and 6 is formed in the fixed mold portion 3, and a runner 7 that connects the sprue 9 and the cavity 5, and the sprue 9 and the cavity 6 are connected. A runner 8 to be connected is formed. The runners 7 and 8 are formed by the parting surfaces of the fixed mold part 3 and the movable mold part 4 in the same manner as the cavities 5 and 6, and the flow path of the molten resin is branched from the spru 9 and is formed in the cavity 5. (6) is connected to the standing surface portion 12 substantially vertically. The runners 7 and 8 communicate with each other. Further, a coating material injection path 21 for injecting a coating material (paint) from the coating material injection port 11 into the cavities 5 and 6 using the injection machine 2 is provided through the runners 7 and 8. In the mold shown in the embodiment, the sprue is a part of the flow path of the molten resin to the cavity, and the molten resin injection port of the mold (opening through which the molten resin is injected from the outside of the mold) It refers to the part from to the runner and generally has a conical shape. In the mold for in-mold coating molding according to the present invention, the flow path of the molten resin is not limited to the one containing sprue and may be sprueless, or from the hot runner to the runner shown in the present specification. A mode in which a molten resin is supplied may be used and is not particularly limited. In the mold shown in the embodiment, the runner is a part of the flow path of the molten resin to the cavity, refers to a portion from the sprue to the cavity, and is provided for each cavity by branching from the sprue.

  The mold 10 is not the surface through which the covering material flows, but the surface on which the runners 7 and 8 are formed, and the surface facing the die 10, and the surface on which the fixed mold portion 3 forms the runners 7 and 8, each has one recess 17 Is different from the conventional mold (see FIG. 5). The concave portion 17 is not a stepped form, but is formed as a smooth concave on the cavity 5 (6) side.

  In performing molding by the in-mold coating molding method, first, the stationary mold part 3 and the movable mold part 4 are clamped by using an injection apparatus (not shown) constituting the molding apparatus, and the sprue 9 to the runner 7, The molten resin is injected and filled into the cavities 5 and 6 through 8 and solidified by cooling to obtain a resin molded product 14. Next, with the resin molded product 14 held in the cavities 5 and 6 of the mold 10, the movable mold portion 4 is separated from the fixed mold portion 3 to slightly open the mold 10, and the resin molded product 14 and A coating material (paint) is injected into the gap 13 formed between the surfaces forming the cavities 5 and 6. The covering material is injected through the gap 18 between the surface of the movable mold portion 4 on which the runners 7 and 8 are formed and the molded body through the covering material injection port 11 through the covering material injection path 21. This is done by entering the gap 13 between the surface of the movable mold part 4 forming the cavities 5 and 6 and the resin molded product 14.

  In the above process, the molten resin injected / filled into the cavities 5 and 6 shrinks with cooling and solidification, and is molded as a resin molded product 14 (see FIG. 2). Due to this shrinkage, a tensile force acts in the longitudinal direction (the arrow direction in FIG. 2) in the resin molded product main body portion 14a formed by the main body portion 16 of the cavity 5 (6), and the standing surface portion 12 (see FIG. 2) of the cavity 5 (6). 2), the resin molded product standing surface portion 14b is pulled.

  On the other hand, a recess 17 is formed in the runner 7 (8), and solidification of the molten resin is delayed in the recess 17, so that the tensile force in the longitudinal direction generated in the molded body 15 formed by the runner 7 (8) is Then, it is absorbed by the molten resin that has not yet been solidified, and the pulling force on the resin molded product standing surface portion 14b is suppressed. Therefore, when the movable mold part 4 is slightly separated from the fixed mold part 3 and the mold 10 is opened, the resin molded product main body part 14 a and the movable mold part 4 formed by the main body part 16 of the cavity 5 (6). Between the resin molded product standing surface portion 14b molded with the standing surface portion 12 of the cavity 5 (6) and the movable mold portion 4, and between the molded body 15 molded with the runner 7 (8) and the movable mold portion. 4, gaps 13 and 18 having a uniform size are formed. Accordingly, the coating material can be introduced from the coating material injection port 11 through the runners 7 and 8 into the gap 13 between the surface on which the cavities 5 and 6 are formed and the resin molded product 14. The resin molded product 14 can be covered, and a high-quality resin molded product can be produced with high efficiency.

  3, FIG. 4 and FIG. 11 are views showing another embodiment of the mold for in-mold coating molding of the present invention. FIG. 3 is a cross-sectional view showing the parting line, and FIG. 4 is an enlarged cross-sectional view of a portion C surrounded by an ellipse in FIG. 3, that is, a rising surface portion of the cavity. It is the same mode. FIG. 11 is a view showing a YY section in FIG. 3, that is, a parting surface of the movable mold part. The illustrated mold 30 is different from the mold 10 in that a concave portion 37 is formed instead of the concave portion 17 of the mold 10, and other than that, the mold 30 is a mold having the same form as the mold 10 (see FIG. 1). is there. Similar to the mold 10, the surface on which the recess 37 is formed is not the surface through which the covering material flows, but is the surface facing the runner 27, 28, and the fixed mold portion 23 is the runner 27, 28. It is a surface which forms. The recess 37 is formed in a step shape in the vicinity of the cavity 25 (26), not a smooth recess.

  In performing molding by the in-mold coating molding method using the mold 30, first, the fixed mold portion 23 and the movable mold portion 24 are clamped using an injection device (not shown) constituting the molding apparatus. The molten resin is injected and filled from the sprue 29 into the cavities 25 and 26 through the runners 27 and 28, and solidified by cooling to obtain a resin molded product 34. Next, with the resin molded product 34 held in the cavities 25 and 26 of the mold 30, the movable mold portion 24 is separated from the fixed mold portion 23, and the mold 30 is slightly opened. A coating material (paint) is injected into the gap 33 formed between the surfaces on which the cavities 25 and 26 are formed. The covering material is injected from the covering material injection port 31 by the injector 22, passes through the covering material injection path 41, and the surface forming the runners 27 and 28 of the movable mold part 24 and the molded body. This is performed by entering the gap 33 between the surface of the movable mold part 24 where the cavities 25 and 26 are formed and the resin molded product 34 through the gap 38 therebetween.

  In the above process, the molten resin injected / filled into the cavities 25 and 26 contracts with cooling and solidification, and is molded as a resin molded product 34 (see FIG. 4). As a result of this contraction, a tensile force acts in the longitudinal direction (in the direction of the arrow in FIG. 4) in the resin molded product main body 34a formed by the main body 36 of the cavity 25 (26), and the standing surface 32 (see FIG. 4), the resin molded product standing surface 34b is pulled.

  On the other hand, the runner 27 (28) has a stepped recess 37, and since the solidification of the molten resin is delayed in the stepped recess 37, the runner 27 (28) is formed in the molded body 35 formed by the runner 27 (28). The tensile force in the longitudinal direction is absorbed by the molten resin that has not yet solidified, and the tensile force on the resin molded product standing surface portion 34b is suppressed. Further, in the mold 30, since the concave portion 37 is formed in a step shape, when the molten resin in the concave portion 37 of the runner 27 (28) is solidified, a molded body (molded) formed by the concave portion 37 of the runner 27 (28). Part of the body 35 fits into the concave portion 37 as a convex portion and restrains the entire molded body 35, so that after the molten resin is solidified in the concave portion 37, shrinkage occurs due to molding of the portion other than the concave portion 37. Even if a tensile force is applied in the longitudinal direction of the runner 27 (28), it resists the tensile force, and the resin molded product standing surface portion 34b formed by the standing surface portion 32 of the cavity 25 (26) is deformed. Absent. Therefore, when the movable mold part 24 is slightly separated from the fixed mold part 23 and the mold 30 is opened, the resin molded product main body part 34 a and the movable mold part 24 formed by the main body part 36 of the cavity 25 (26). Between the resin molded product standing surface portion 34b molded with the standing surface portion 32 of the cavity 25 (26) and the movable mold portion 24, and between the molded body 35 molded with the runner 27 (28) and the movable mold portion. 24, the gaps 33 and 38 having a uniform size are formed. Therefore, the coating material can be introduced from the coating material injection port 31 into the gap 33 between the surface forming the cavities 25 and 26 and the resin molded product 34 via the runners 27 and 28, and the coating film has a uniform thickness. The resin molded product 34 can be covered.

  8 and 9 are views showing still another embodiment of the in-mold coating mold of the present invention. FIG. 8 is a sectional view showing a parting line, and FIG. 9 is a view showing a DD section in FIG. 8, that is, a parting surface of a movable mold part. A mold 80 shown in FIG. 8 is different from the molds 10 and 30 in that a recess 87 is formed instead of the recess 17 of the mold 10 and the recess 37 of the mold 30. Otherwise, the mold 10 ( This is a mold in the same manner as the mold 30 (see FIG. 1) and the mold 30 (see FIG. 3). Unlike the molds 10 and 30, the surface on which the recess 87 is formed is a surface substantially parallel to the opening and closing direction of the mold 80 among the surfaces (inner surfaces) on which the movable mold part 74 forms the runners 77 and 78. (See FIG. 9). This is not the surface where the covering material flows among the surfaces forming the runners 77, 78, nor the surface facing the surface where the covering material flows among the surfaces forming the runners 77, 78. Two recesses 87 are formed in a step shape in the vicinity of the cavities 75 and 76, like the recesses 37.

  When performing molding by the in-mold coating molding method using the mold 80, first, the fixed mold portion 73 and the movable mold portion 74 are clamped using an injection device (not shown) constituting the molding apparatus. The molten resin is injected and filled from the sprue 79 into the cavities 75 and 76 through the runners 77 and 78, and solidified by cooling to obtain a resin molded product (not shown). Next, with the resin molded product held in the cavities 75 and 76 of the mold 80, the movable mold part 74 is separated from the fixed mold part 73 to slightly open the mold 80, and the resin molded product and the cavity 75 are opened. , 76 is injected into a gap (not shown) formed between the surfaces forming the coatings 76. The coating material is injected from the coating material injection port 81 by the injector 72, passes through the coating material injection path 71, and forms the runners 77 and 78 of the movable mold portion 74 and the molded body. This is performed by entering a gap between the surface of the movable mold portion 74 forming the cavities 75 and 76 and the resin molded product via a gap (not shown).

  In the above process, the molten resin injected and filled in the cavities 75 and 76 contracts with cooling and solidification, and is molded as a resin molded product. Due to this shrinkage, a tensile force acts in the longitudinal direction in the resin molded product main body (not shown) formed by the main body (not shown) of the cavities 75 and 76, and molding is performed at the standing surfaces (not shown) of the cavities 75 and 76. The formed resin molded product standing surface portion is pulled.

  On the other hand, each of the runners 77 and 78 is formed with two stepped recesses 87, and the solidification of the molten resin is delayed in the stepped recesses 87. The tensile force in the longitudinal direction generated in (No) is absorbed by the molten resin that has not yet been solidified, and the tensile force on the standing surface portion of the resin molded product is suppressed. Further, in the mold 80, since the concave portion 87 is formed in a step shape, when the molten resin in the concave portion 87 of the runners 77 and 78 is solidified, the molded body formed by the concave portion 87 of the runners 77 and 78 becomes the convex portion. Since it fits into the concave portion 87 and restrains the entire molded body, temporarily, after solidification of the molten resin in the concave portion 87, shrinkage occurs due to molding of portions other than the concave portion 87, and pulling force is generated in the longitudinal direction of the runners 77 and 78. Even if the works, it resists the pulling force, and deformation does not occur in the standing surface portion of the resin molded product molded by the standing surface portions of the cavities 75 and 76. Therefore, when the movable mold part 74 is slightly separated from the fixed mold part 73 and the mold 80 is opened, a gap between the resin molded product main body formed by the main body parts of the cavities 75 and 76 and the movable mold part 74 is obtained. In either of the resin molded product standing surface portion molded at the standing surface portions of the cavities 75 and 76 and the movable mold portion 74, or between the molded body molded by the runners 77 and 78 and the movable mold portion 74. A gap having a uniform size is formed. Accordingly, the coating material can be introduced from the coating material injection port 81 into the gap between the surface on which the cavities 75 and 76 are formed and the resin molded product through the runner 77.78, and the resin molding is performed with a uniform thickness coating film. It is possible to coat the product.

  The embodiments of the in-mold coating mold and the in-mold coating forming method of the present invention have been described above, but the present invention should not be construed as being limited thereto, and does not depart from the scope of the present invention. Insofar as various changes, modifications and improvements can be made based on the knowledge of those skilled in the art. For example, the drawings show preferred embodiments of the present invention, but the present invention is not limited by the information shown in the drawings. In practicing or verifying the present invention, means similar to or equivalent to those described in the present specification may be applied, but preferred means are those described above.

  The mold for in-mold coating molding and the in-mold coating molding method according to the present invention include forming at least one concave portion on a surface excluding a surface on which a coating material flows among surfaces forming respective branched runners in the mold. Since it is possible to suppress the tensile force on the resin molded product molded in the cavity by delaying the solidification of the molten resin, instead of forming the recess, a heating means such as a heater may be provided in that place, Means such as a place where the place is made of a material having a low thermal conductivity and hardly dissipates heat may be used.

  The mold for in-mold coating molding and the in-mold coating molding method of the present invention may be used as molding means for any resin molded product. In particular, it can be suitably used for molding products that require high quality in appearance, such as motorcycle parts, automobile parts, home appliances, and housing equipment.

It is sectional drawing which shows one Embodiment of the metal mold | die for in-mold coating shaping | molding of this invention. It is sectional drawing to which the B section enclosed by the ellipse in FIG. 1 was expanded. It is sectional drawing which shows other embodiment of the metal mold | die for in-mold coating forming of this invention. It is sectional drawing to which the C section enclosed by the ellipse in FIG. 3 was expanded. It is sectional drawing which shows an example of the conventional metal mold | die for in-mold coating molding. It is the figure showing the AA cross section in FIG. It is sectional drawing to which the E section enclosed by the ellipse in FIG. 5 was expanded. It is sectional drawing which shows other embodiment of the metal mold | die for in-mold coating forming of this invention. It is a figure showing DD section in FIG. It is the figure showing the XX cross section in FIG. It is the figure showing the YY cross section in FIG.

Explanation of symbols

2, 22, 52, 72 ... injection machine, 3, 23, 53, 73 ... fixed mold part, 4, 24, 54, 74 ... movable mold part, 5, 6, 25, 26, 55, 56, 75 76, cavity, 7, 8, 27, 28, 57, 58, 77, 78 ... runner, 9, 29, 59, 79 ... sprue, 10, 30, 50, 80 ... mold, 11, 31, 61, 81 ... Covering material injection port, 12, 32, 62 ... Standing surface part (of cavity), 15, 35, 65 ... Molded body, 16, 36, 66 ... (Main part of cavity), 14, 34, 64 ... Resin molding 14a, 34a, 64a ... resin molded product main body, 14b, 34b, 64b ... resin molded product standing surface, 21, 41, 51, 71 ... coating material injection path.

Claims (8)

Consists of a fixed mold part and a movable mold part. By the fixed mold part and the movable mold part, a plurality of cavities, which are molding spaces for resin molded products, and molten resin are injected into the cavities. A mold for in-mold coating molding in which a runner for performing and a coating material injection path for injecting a coating material into the plurality of cavities are formed,
The runner is connected to each of the plurality of cavities, and at least one recess is formed on a surface of each of the surfaces forming the runners connected to the plurality of cavities except for the surface through which the covering material flows. In-mold coating mold.   The mold for in-mold coating molding according to claim 1, wherein the concave portion is formed in a step shape.   The mold for in-mold coating molding according to claim 1 or 2, wherein a plurality of the recesses are formed.   The mold for in-mold coating molding according to any one of claims 1 to 3, wherein the recess is formed in the vicinity of the cavity. A mold composed of a fixed mold part and a movable mold part is used, and molten resin is filled into a plurality of cavities formed by the mold through respective runners connected to the plurality of cavities. Then, after the molten resin is solidified to obtain a plurality of resin molded products, the movable mold portion is separated from the fixed mold portion while the resin molded products are held in the cavities. The mold is opened slightly, and the covering material is injected through the runner into the gap formed between the surface of the movable mold part or the fixed mold part forming the cavity and the resin molded product. , A method of coating the surface of the resin molded product in a mold,
By forming at least one recess on the surface of the mold that forms the respective runners connected to the plurality of cavities except the surface through which the covering material flows, and delaying the solidification of the molten resin in the recess An in-mold coating molding method that suppresses a tensile force applied to a resin molded product molded in a cavity.   The in-mold coating forming method according to claim 5, wherein the recess is formed in a step shape.   The in-mold coating forming method according to claim 5 or 6, wherein a plurality of the concave portions are formed.   The in-mold coating forming method according to any one of claims 5 to 7, wherein the recess is formed in the vicinity of the cavity.

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