JP2008290414A - Die for coating molding in die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for coating molding in a die capable of coating homogeneously with forming a homogenous space between a die surface on a coating surface side and a molding article and of obtaining a coated molding article having no stain by preventing leaking of a coating agent outside the die upon coating molding in a die. <P>SOLUTION: The die for coating molding in a die for molding a synthetic resin is equipped with means for introducing a coating agent into a molding die for conducting surface coating on a synthetic resin molded article in the molding die, wherein the die for coating molding in a die comprises a part combining a main die cavity constructed by a male die and a female die which can be divided into at least two parts with a shear edge, a cavity extended in an opening-closing direction of the die is formed on a whole peripheral part, a ditch part is formed in the cavity having extended male and female dies and the ditch part on a coating surface side is formed continuously around the whole peripheral part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, after molding a synthetic resin in a mold, a coating agent is injected between the resin molded product and the mold cavity surface in the mold and cured, thereby coating the surface of the resin molded product. The present invention relates to a mold for in-mold coating molding used in an in-mold coating molding method.

  Conventionally, the surface of a molded product has been coated in order to improve the durability and appearance quality of the synthetic resin molded product.

  In a conventional coating method, a molded product molded in a mold is taken out from the mold and then coated by a spray method or the like.

  However, in recent years, there has been an active movement to regulate environmental problems, in particular, the discharge of volatile organic solvents called VOCs. Therefore, in-mold coating molding methods have been proposed in which molding and painting are performed in the same mold. It was.

  The in-mold coating molding method was originally an improvement in quality when adopting a glass fiber reinforced plastic with an unsaturated polyester resin as a matrix, called “SMC” as a molding material, especially in the automotive industry with a high demand for appearance quality. It has been developed for the purpose of shortening the painting process. Japanese Patent No. 1858686 is known as a typical in-mold coating forming method.

  According to this method, when the in-mold coating agent is injected into the mold, the coating agent is injected at a pressure substantially exceeding the pressure in the mold while the mold is held in the molded position, and the molded product is lifted. It is characterized by preventing.

  In general, a mold for compression molding is used in such an in-mold coating method. This is a mold having a shear edge structure portion, and “SMC”. The molding material, which has a good flowability and a very small property of shrinkage in curing, can seal the shear edge structure portion with the molding material during molding, and the coating agent during the subsequent filling of the coating agent This is because it is possible to prevent outflow from the cavity.

  Attempts have been made to apply such an in-mold coating method to a reaction injection molding method of dicyclopentadiene or an injection molding method of thermoplastics (Japanese Patent No. 3617807, Japanese Patent No. 3798436, Japanese Patent Laid-Open No. 2001). -038783 etc.).

  When the coating agent is injected into the mold, a method of slightly opening the mold or reducing the mold clamping pressure is taken in order to facilitate the injection of the paint. However, at this time, the space between the mold surface and the molded product, which is generated by increasing the distance between the male mold and the female mold, is in a vacuum state or a reduced pressure state. Normally, since the ejector pin is not provided on the coated surface side mold, the pressure is reduced between the coated surface side mold surface and the molded product, the molded product is pulled by the coated surface side mold, and the molded product is placed in the mold. By floating, the formation of the gap between the coated surface side mold and the molded product becomes non-uniform, preventing uniform coating.

  Further, these molding materials have a molding shrinkage ratio larger than that of the “SMC”, and it is difficult to completely seal with the molding material formed on the shear edge portion.

  In order to solve these problems, Patent Document 1 proposes a mold for in-mold coating molding that has a shear edge structure and is provided with an elastic sealing material such as an O-ring at the shear edge portion.

  However, in the in-mold coating mold described in Patent Document 1, it is possible to prevent leakage of the coating material at the O-ring portion, but the coating material that has entered the O-ring groove is cured, The effect of the elastic seal was weakened, and the O-ring had to be replaced frequently, which had the problem of hindering continuous molding. In addition, when injecting the coating agent into the mold, it is easy to inject the paint, so the mold is slightly opened by the O-ring when the mold is slightly opened or the clamping pressure is reduced. It had the problem of preventing uniform coating.

  Further, Patent Document 2 proposes an in-mold coating mold in which an auxiliary cavity is provided over the entire circumference of the mold cavity and the auxiliary cavity is filled with resin to prevent paint leakage.

  However, there is a problem that paint leakage may occur due to shrinkage of the resin filled in the auxiliary cavity.

  Patent Document 3 proposes an in-mold coating mold in which an auxiliary cavity is provided over the entire circumference of the mold cavity, and a groove portion formed over the entire circumference of the auxiliary cavity is provided on the coating surface side of the auxiliary cavity. Yes.

  Although this mold can prevent the coating material from leaking, when injecting the coating material into the mold, it is easier to inject paint, so the mold can be opened slightly or the clamping pressure can be reduced. In addition, the molded product floats in the mold, so that no space for injection of the coating material is generated, a high pressure is required for the injection of the coating material, and the molded product with a shape such as a rib or boss only prevents uniform coating. In addition, there was a problem that cracks and deformation occurred at the bases of the ribs and bosses.

  4 and 5 schematically explain the above problem. As shown in FIG. 4 (a), the resin molded body filled with the grooves provided in the auxiliary cavity and formed with the protrusions is formed of the resin molded body at the protruding portion when the mold is opened as shown in FIG. 4 (b). Thus, the entire molded product is pulled together with the coating side mold. At this time, if there is a rib structure, the rib portion is left behind in the uncovered mold, and deforms as shown in FIG. 4B, causing cracks and deformation at the base of the rib.

  Fortunately, if the rib part is removed from the uncoated mold, it does not fit in the original position when re-clamping due to shrinkage of the molding resin as shown in FIG. ), It is difficult to coat with a uniform film thickness.

  On the other hand, Patent Documents 4 to 7 propose a structure of a mold for in-mold coating molding using a so-called parting structure that does not have a shear edge structure.

  In Patent Document 4, an auxiliary cavity communicating with the main cavity is provided on the parting surface over the entire circumference of the main cavity. Further, the auxiliary cavity is provided with a coating material on the mold surface on which the coating agent is injected. There has been proposed a mold characterized in that a groove for preventing outflow is provided. However, in such a mold structure, when trying to inject the coating material into the mold, it is easy to inject the coating material. When the sealing surface is opened, the coating material gets over the protruding portion of the groove and the coating material leaks out of the mold.

  Patent Document 5 discloses a subcavity that is connected to the main cavity over the entire circumference of the main cavity on the parting surface, and an inverted trapezoidal protrusion having a large tip protruding into the subcavity inside the outer peripheral portion on the coating surface side of the subcavity. In addition, a technique is disclosed in which the inverted trapezoidal protrusion is provided with a high-temperature portion, and in particular, prevents leakage of the coating material during re-clamping after the coating material is injected. However, in such a mold structure, when the coating agent is injected into the mold, it is described in such a manner that a predetermined interval is opened. Further, in the specification [0013], the mold is slightly opened to form a gap for coating agent injection. In this state, the space is in a vacuum state. In such a state, unless a force (resistance) that overcomes the vacuum state is applied to the core side (non-painted surface side), the molded product is struck to the cavity side, and a predetermined space cannot be obtained. In addition to requiring a large amount of pressure for the injection, there was a problem that a uniform coating could not be obtained because the gaps were not uniform.

  Patent Document 6 discloses a subcavity communicating with the main cavity over the entire circumference of the main cavity on the parting surface, a movable core that advances and retreats into the subcavity on the inner side of the subcoating surface side of the subcavity, There has been disclosed a technique for providing a high temperature portion at a position facing the movable core and preventing leakage of the coating material particularly during re-clamping after the coating material is injected. However, in this mold structure, for the same reason as in Patent Document 5, a predetermined space cannot be obtained, and not only a large pressure is required for injecting the coating material, but also the gap is non-uniform, so that it is uniform. The fact that the coating cannot be obtained and the movable core that prevents the coating agent from leaking over the entire circumference of the subcavity requires a considerable processing accuracy in the case of a molded product having a complicated three-dimensional shape. Become.

  Patent Document 7 discloses a main cavity for molding a resin molded product having a desired shape, and a fixed mold that forms the main cavity and a subcavity that is formed so as to be connected to the dividing surface of the movable mold and surround the dividing surface. And a mold in which a plurality of groove portions surrounding the entire circumference of the split surface along the shape of the subcavity are formed on the cavity surfaces of the fixed mold and the movable mold that form the subcavity. . However, in this mold structure, when the mold is slightly opened to inject the coating agent, a predetermined space is obtained for the same reason as in Patent Document 5, depending on the resistance and shape of the fixed side groove and the movable side groove. In addition, not only does it require a great deal of pressure to inject the coating material, but the gaps are non-uniform, so that a uniform coating cannot be obtained. There was a problem of leaking out of the mold.

In Patent Document 1 to Patent Document 7, when the coating agent is cured, the mold is opened, and when the coated molded product is taken out of the mold, a vacuum state is temporarily generated between the coated surface side cavity and the coated molded product. Therefore, burrs and dust around the mold are sucked between the coated surface side cavity and the coated molded product, and these dust adheres to the surface of the molded product to reduce the product value or adhere to the coated surface side cavity. There was a problem of surface defects in the next shot.
JP-A-6-328505 JP 2001-138334 A JP 2003-191286 A JP 9-48044 A JP 2002-172656 A JP 2002-172657 A JP 2006-256088 A

  An object of the present invention is to make it easier to inject paint when injecting a coating material into a mold, so that the molded product floats in the mold when the mold is slightly opened or when the clamping pressure is reduced. In order to achieve a uniform in-mold coating by forming a uniform space between the coated surface side mold surface and the molded product, and during the in-mold coating molding, It is an object of the present invention to provide a mold for in-mold coating molding which can prevent a leakage to the surface and can obtain a coated molded product without adhesion of dust or the like.

As a result of intensive studies in order to solve the above problems, the present inventors have found that the above problems can be achieved by the following configuration, and have reached the present invention. That is, the mold for in-mold coating molding according to the present invention is:
1. A mold for in-mold coating molding for synthetic resin molding, comprising a means for injecting a coating agent into a molding die in order to apply a surface coating to the synthetic resin molded product in the molding die, A cavity extending in the opening and closing direction of a mold in an in-mold coating mold having a mold main cavity composed of a male mold and a female mold separable into two and a fitting portion of a shear edge structure Is provided in the cavity extending in both the male mold and the female mold, and the groove section of the covering surface side cavity is a continuous groove section over the entire circumference.

  2. In the first aspect, the cavity extending in the opening / closing direction is a part of the mold main cavity, or is provided in an auxiliary manner in communication with the mold main cavity.

  3. In the above 1 or 2, an air vent is provided on the coating surface side of the mold main cavity.

  According to the mold for in-mold coating molding of the present invention, for example, the resin filled in the mold cavity by reaction injection molding of dicyclopentadiene or injection molding of thermoplastics such as ABS resin is cured or solidified and contracted, Even when a gap is formed between the mold and the mold, the resin filled in the groove provided in the cavity portion of the non-coated surface extending in the mold opening and closing direction becomes a protrusion, and the coating agent is placed in the mold. In order to make it easy to inject paint when injecting, the mold is prevented from being slightly lifted in the mold when the mold is slightly opened or the clamping pressure is reduced, and a uniform in-mold coating is achieved. In addition, when filling the coating material into the mold, the resin filled in the groove provided in the cavity portion on the coating surface side extending in the mold opening / closing direction becomes a protrusion to prevent the coating material from leaking out of the mold. Effectively prevent.

  Also, when removing the coated molded product from the mold, release the mold clamping force of the molding machine and operate the air vent just before releasing to send air into the mold to make the pressure in the mold higher than atmospheric pressure. In this way, dust can be prevented from entering the mold, and dust can be effectively prevented from adhering to the coated molded product and from the coated surface side mold cavity.

  Hereinafter, embodiments of an in-mold coating mold according to the present invention will be described in detail with reference to the drawings. 1, 2 and 3 relate to a preferred example of an embodiment according to the present invention. FIG. 1 is a cross-sectional view for explaining the structure of an in-mold coating molding die, and FIG. 2 is an in-mold coating molding. The protrusion formed by the groove formed in the mold for the mold is uncovered without the molded product floating up against the mold displacement when the mold is opened in a small amount to inject the coating agent or the mold clamping pressure is released FIG. 3 is a conceptual diagram for explaining a behavior that is fixed to a surface side mold, forms a predetermined space, and further prevents leakage of the coating agent to the outside of the mold. FIG. In order to prevent galling, this is an example in which the cutting direction of the biting structure portion is tapered. Moreover, in order to prevent the protrusions formed on the non-covered surface side from interfering when the molded product is removed, the slide structure is provided.

  A preferred example of the in-mold coating mold according to the present invention will be described in detail below with reference to FIG.

  The mold according to the present invention includes a mold main cavity (hereinafter referred to as “main cavity”) 1 and an auxiliary cavity 2 formed by a movable mold 5 and a fixed mold 6. A fitting portion having a shear edge structure (cut-off structure) is formed, and the fixed mold is provided with a molded resin injection machine 8 and a coating material injection machine 9.

  The mold shown in FIG. 1 is configured to form an auxiliary cavity 2 extending in the opening / closing direction of the mold over the entire circumference of the main cavity 1. In addition, the fitting portion of the biting structure and the main cavity 1 communicate with each other through the auxiliary cavity 2.

  Further, in the embodiment shown in FIG. 1, a groove having a rectangular cross section that is continuous over the entire circumference of the auxiliary cavity 2 on the outer peripheral side (covered surface side) and the inner peripheral side (non-coated surface side) of the auxiliary cavity 2. 3 and 4 were provided.

  The grooves 3 and 4 formed in the in-mold coating mold shown in FIG. 1 have a rectangular cross section, but the shape of the grooves 3 and 4 is not limited to this. For example, as shown in FIG. It may be a triangle or trapezoid. Further, the groove 3 and the groove 4 may have different shapes.

  Moreover, the groove part 4 formed in the non-coating surface side does not need to form a groove part over the auxiliary cavity whole periphery. On the other hand, it is essential that the groove portion 3 formed on the coated surface side is formed as a continuous groove portion over the entire circumference of the auxiliary cavity.

  The depth of the groove 3 (the length in the direction perpendicular to the mold opening / closing direction) is related to the thickness of the auxiliary cavity in which the groove 3 is formed, and more specifically with respect to the thickness direction of the resin molded in the auxiliary cavity. Related to mold shrinkage. That is, it is necessary to have a depth that can sufficiently form a protrusion enough to prevent leakage of the coating material even when the resin in the auxiliary cavity portion contracts.

  The depth of the groove 3 is preferably (t × s × 1/100 + 0.05) mm or more and (t × s × 1/100 + 1.0) mm or less. Here, t is the thickness of the auxiliary cavity, and s is the molding shrinkage [%] in the thickness direction.

  The width of the groove 3 is preferably in the range of 0.3 to 1 mm, but is not limited thereto.

  The width of the auxiliary cavity in the opening / closing direction may be 0.5 mm or more.

  The thickness of the auxiliary cavity is preferably in the range of 0.2 to 3 mm, but is not limited thereto.

  The size of the groove portion 4 is related to the size of the groove portion 3 for the purpose of preventing the molded body from being lifted when the mold is opened at the time of injecting the coating agent. The size of the groove portion 4 is preferably larger than that of the groove portion 3. The size of the groove on the coated surface side and the non-coated surface side is preferably in the range of the total volume ratio of 1 / 1.1-1 / 100, but is not limited thereto.

  Further, the grooves 3 and 4 are not necessarily formed in the auxiliary cavity, but may be provided in the main cavity extending in the opening / closing direction.

  In addition, the travel length in the fitting portion of the shear edge structure depends on the mold opening amount when the coating agent is injected into the mold, but may be (mold opening amount + 1) mm or more.

  Further, an air vent may be provided on the coated surface side of the main cavity.

A commercially available injector can be used as the coating agent injector. Examples include, but are not limited to, manufactured by MORRELL, manufactured by EMC ² , manufactured by Claus Maphi Japan, and manufactured by Met Japan.

  In addition, although the injection machine 9 in this Embodiment was comprised so that a coating agent might be inject | poured from a movable side in FIG. 1, it is not limited to a movable side, Between a coating surface side mold surface and a molded article What is necessary is just to comprise so that a coating | coated agent can be inject | poured into the clearance gap part produced in this. Further, the number of injection machines is not limited to one, and a plurality of injection machines may be used depending on the shape and size of the molded product.

  FIG. 1 shows two temperature control pipes for adjusting the mold temperature, that is, 10 for heating medium and 11 for cooling medium. This is a high temperature of, for example, 100 ° C. or higher when the coating is cured. To shorten the curing time of the coating agent and to remove the molded product from the mold, for example, cool it to 60 ° C. or less, and use it to keep the deformation and appearance of the coated molded product in good condition. But it ’s okay.

  As for the heating medium pipe (heating temperature control pipe), the main cavity end portion is likely to be low temperature, and the coating material in this portion is liable to cause poor curing. preferable. Alternatively, an electric heater may be used as an auxiliary.

  Although not shown, it is preferable to provide a heel block on the mold in order to prevent galling at the cut-off portion when the movable mold and the stationary mold are opened and closed.

  Hereinafter, the present invention will be described in more detail with reference to FIGS. 1 and 2, but the scope of the present invention is not limited to these examples.

A mold for molding an automobile spoiler part having a surface area of about 0.5 m ² was used, and the mold temperature was set to 90 ° C. for the movable mold (coated surface side) and 50 ° C. for the fixed mold (non-coated surface side).

  First, as a first step, the mold is clamped by a mold clamping device of a RIM molding machine (not shown). Then, "Meton" (made by RIMTEC), which is a molding resin, is injected and reaction-cured in the mold. FIG. 2A shows a state in which the main cavity 1 is filled with resin. Next, as shown in FIG. 2 (b), the movable mold 5 is opened by about 1 mm at a stage (after 70 seconds from the injection of the molding resin) when the methone, which is a molding resin, is cured to the extent that it does not deform even when the mold is opened. . At this time, the resin molded body is held at that position by the fixed mold (non-coated surface side) because the resin molded body protrusion formed in the non-coated surface side groove 4 becomes a resistance. Therefore, a space for injecting the coating agent is formed between the movable mold (covering surface side) surface and the molded body.

  At this time, the protrusion formed in the groove 3 is crushed on the movable mold (covering surface side) surface to fill a gap due to shrinkage of the molding resin.

  Next, 100 cc of the coating agent was injected into the space through a coating agent injector.

  Immediately after the coating agent was injected, the mold was re-clamped to spread the coating agent injected into the space part over the entire space part and at the same time hold the coating material under pressure for 180 seconds to cure the coating agent.

  When the in-mold coating is performed using the in-mold coating molding die of the present invention, as shown in FIG. 2C, a uniform in-mold molded product having no leakage of the coating agent can be continuously molded.

  The composition of the coating material used in this example is shown in Table 1.

It is typical sectional drawing which shows one Example of the metal mold | die for in-mold coating forming of this invention. It is a fragmentary sectional view explaining operation | movement of the said Example. It is a fragmentary sectional view of the example which provided the slide structure in which the biting structure part was tapered in the said Example. It is a fragmentary sectional view explaining the problem of the conventional metal mold | die for in-mold coating molding. It is a fragmentary sectional view explaining the problem of the conventional metal mold | die for in-mold coating molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main cavity 2 Auxiliary cavity 3 Covering surface side groove part 4 Non-coating surface side groove part 5 Movable type (covering surface side)
6 Fixed type (non-coated surface side)
7 Ejector pin 8 Molding resin injection machine 9 Coating material injection machine 10 Heating medium pipe 11 Cooling medium pipe 12 Air vent

Claims (3)

  A mold for in-mold coating molding for synthetic resin molding, comprising a means for injecting a coating agent into a molding die in order to apply a surface coating to the synthetic resin molded product in the molding die, A cavity extending in the opening and closing direction of a mold in an in-mold coating mold having a mold main cavity composed of a male mold and a female mold separable into two and a fitting portion of a shear edge structure For the in-mold coating, characterized in that a groove is provided in the cavity extending in both the male and female molds, and the groove of the cavity on the coated surface side is a continuous groove over the entire circumference. Mold.   The cavity extending in the opening / closing direction is a part of the mold main cavity, or is provided in an auxiliary manner in communication with the mold main cavity. Mold for in-mold coating molding.   The mold for in-mold coating molding according to claim 1 or 2, wherein an air vent is provided on the coating surface side of the mold main cavity.

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