Coated molded article and method for producing the same

Abstract

Provided is a coated molded article which improves adhesion between a primary resin and a coating film and which can be produced without requiring additional facilities which contribute to a longer takt time. The coated molded article comprises: a non-woven fabric; a primary resin which is solidified and provided to one surface of the non-woven fabric; and a coating film which is made of a reactive coating material and provided to the other surface of the non-woven fabric.

Description

Painted molded product and its manufacturing method

[0001] The present disclosure relates to a painted molded product and a method for producing a painted molded product by forming a paint film on a resin molded product in a mold.

[0002] Conventionally, when forming a paint film on a resin molded product, the resin molded product is formed by injection molding in a mold, and then the resin molded product is removed from the mold and painted with paint by spray painting or the like, and then dried.In contrast to this, an in-mold coating (IMC) technology is becoming popular, in which a resin molded product is formed by injection molding in a mold, and then the cavity mold is changed and a paint film is formed inside the mold.

[0003] As with painting outside the mold, when the primary resin used for painting inside the mold is a poorly adhesive resin such as olefin (PP) or polystyrene (PS), the paint and the primary resin are incompatible, the paint film does not adhere well, and olefin etc. cannot be used as the primary resin.

[0004] In order to use these poorly adhesive resins as the primary resin, it is necessary to develop a primer (undercoat) treatment method suited to the poorly adhesive resin, and a paint composition tailored to the resin. This has led to problems such as a lengthy development routine, the need to use different primers and paints for each resin, which makes manufacturing more complicated, and the low versatility of the primers and paints, which increases material costs.

[0005] Furthermore, since paints for inside-mold coating are solvent-free, they do not have the effect of roughening the surface of the primary resin with a solvent, and tend to rely on chemical interactions between the paint and the resin, which makes it difficult to achieve better adhesion than conventional coatings.

[0006] Japanese Patent Application Laid-Open No. 2002-225075

[0007] In in-mold painting that does not use solvent-containing paint, one method for improving adhesion between the primary resin and the paint is to corrode the surface of the primary resin molded product with a corrosive gas such as ozone after the primary resin molding, and then pour the paint onto the surface of the primary resin molded product to improve adhesion (see, for example, Patent Document 1).

[0008] However, the above method requires equipment such as an ozone generator and a recovery mechanism, and the takt time from ozone injection to ozone recovery is long, which results in high production costs for molded products.

[0009] Therefore, an object of the present disclosure is to provide a painted molded product that can be manufactured without requiring additional equipment that increases the tact time, and that has improved adhesion between the primary resin and the paint film.

[0010] The coated molded product according to the present disclosure comprises a nonwoven fabric, a solidified primary resin provided on one side of the nonwoven fabric, and a coating film made of a reactive paint provided on the other side of the nonwoven fabric.

[0011] The method for manufacturing a painted molded product according to the present disclosure includes the steps of preparing a resin molded product having a nonwoven fabric on the surface of a primary resin, clamping a core mold for a paint film in which the resin molded product is placed and a cavity mold for a paint film, filling a paint cavity defined between the nonwoven fabric of the resin molded product and the cavity mold for a paint film with a reactive paint to form a paint film made of the reactive paint on the nonwoven fabric, and opening the core mold for a paint film and the cavity mold for a paint film to obtain a painted molded product having the nonwoven fabric, a solidified primary resin provided on one side of the nonwoven fabric, and a paint film provided on the other side of the nonwoven fabric.

[0012] The coated molded article according to the present disclosure can be manufactured without requiring additional equipment that increases the tact time, and has high adhesion between the primary resin and the coating film.

[0013] 1 is a flowchart of a method for manufacturing a coated molded product according to embodiment 1. FIG. 2 is a specific flowchart of a series of steps for obtaining the resin molded product of FIG. 1. FIG. 3 is a specific flowchart of a series of steps for obtaining the coated molded product of FIG. 1. FIG. 4 is a schematic cross-sectional view showing a step of clamping a primary resin molding cavity mold having a nonwoven fabric arranged on a surface facing the primary resin molding core mold, and the primary resin molding core mold. FIG. 5 is a schematic cross-sectional view showing a step of injection molding a primary resin into a molding cavity defined between the primary resin molding core mold and the nonwoven fabric arranged in the primary resin molding cavity mold. FIG. 6 is a schematic cross-sectional view showing a step of opening the primary resin molding core mold and the primary resin molding cavity mold to obtain a resin molded product having nonwoven fabric on the surface of solidified primary resin. FIG. 7 is a schematic cross-sectional view showing a step of clamping a paint film core mold having a resin molded product arranged thereon, and the paint film cavity mold. 5A , 5B, and 5C are schematic cross-sectional views showing a process of filling a coating cavity defined between the nonwoven fabric of a resin molded product and a cavity mold for a coating film with a reactive coating material to form a coating film made of the reactive coating material on the nonwoven fabric. FIG. 5B is a schematic cross-sectional view showing a process of opening the core mold for a coating film and the cavity mold for a coating film to obtain a coated molded product having a nonwoven fabric, a solidified primary resin provided on one side of the nonwoven fabric, and a coating film provided on the other side of the nonwoven fabric. FIG. 5C is a schematic cross-sectional view showing the cross-sectional structure of a coated molded product according to Embodiment 1. FIG. 5A is an enlarged cross-sectional view of portion A of FIG. 5A . FIG. 5B is a schematic cross-sectional view showing a schematic cross-sectional structure of a coated molded product according to Example 1. FIG. 5C is an optically enlarged photograph (a) and an optically enlarged photograph (b) of the coating film surface of the coated molded product according to Example 1 at 50x magnification and an optically enlarged photograph (b) of the coating film surface of the coated molded product according to Example 1. FIG. 5C is an optically enlarged cross-sectional photograph showing a cross-sectional structure of the coated molded product according to Example 1 at 200x magnification. FIG. 5D is a schematic cross-sectional view showing a schematic cross-sectional structure of a coated molded product according to Comparative Example 1. 1A is a 50x optical magnification photograph and FIG. 1B is a 200x optical magnification photograph of the coating film surface of the coated molded article according to Comparative Example 1. FIG. 1B is a 200x optical magnification photograph of the cross section of the coated molded article according to Comparative Example 1.

[0014] The coated molded product of the first aspect comprises a nonwoven fabric, a solidified primary resin provided on one side of the nonwoven fabric, and a coating film made of a reactive paint provided on the other side of the nonwoven fabric.

[0015] A coated molded article according to a second aspect is the coated molded article according to the first aspect, wherein the nonwoven fabric is made of two or more materials having different melting points.

[0016] In a third aspect of the coated molded product, in the second aspect, the nonwoven fabric may be such that part or all of the material having a relatively low melting point dissolves between the other fibers of the nonwoven fabric as the fiber shape is deformed and melts, filling some of the gaps in the nonwoven fabric and smoothing the surface of the nonwoven fabric.

[0017] A coated molded article according to a fourth aspect is any one of the first to third aspects, wherein the nonwoven fabric may be a color similar to that of the primary resin.

[0018] A coated molded article according to a fifth aspect is any one of the first to fourth aspects, wherein the reactive paint may contain a dye or a pigment.

[0019] A sixth aspect of the coated molded article is any one of the first to fifth aspects, wherein the coating film may have a grain or texture on the surface opposite to the primary resin side.

[0020] The coated molded article according to the seventh aspect is any one of the first to sixth aspects, wherein the surface roughness of the nonwoven fabric at the interface with the coating film may be smoother than the surface roughness at the interface with the primary resin.

[0021] The coated molded article according to an eighth aspect is any one of the first to seventh aspects, wherein the coating film may have a thickness of 70 μm or more.

[0022] The method for manufacturing a painted molded product according to the ninth aspect includes the steps of preparing a resin molded product having a nonwoven fabric on the surface of a primary resin, clamping a core mold for a paint film in which the resin molded product is placed and a cavity mold for a paint film together, filling a paint cavity defined between the nonwoven fabric of the resin molded product and the cavity mold for a paint film with reactive paint to form a paint film made of the reactive paint on the nonwoven fabric, and opening the core mold for a paint film and the cavity mold for a paint film to obtain a painted molded product having the nonwoven fabric, a solidified primary resin provided on one side of the nonwoven fabric, and a paint film provided on the other side of the nonwoven fabric.

[0023] In the method for manufacturing a painted molded product according to the tenth aspect, in the above-mentioned ninth aspect, the step of preparing a resin molded product having a nonwoven fabric on the surface of the primary resin may include the steps of clamping a cavity mold for primary resin molding, having a nonwoven fabric arranged on the surface facing the core mold for primary resin molding, and the core mold for primary resin molding, injection molding the primary resin into a molding cavity defined between the core mold for primary resin molding and the nonwoven fabric arranged in the cavity mold for primary resin molding, and opening the core mold for primary resin molding and the cavity mold for primary resin molding to obtain a resin molded product having a nonwoven fabric on the surface of the solidified primary resin.

[0024] The method for producing a coated molded product according to the eleventh aspect may, in the tenth aspect, include a step of shaping or smoothing the surface of the nonwoven fabric before placing the nonwoven fabric in the core mold for primary resin molding.

[0025] A twelfth aspect of the method for producing a coated molded article is the method of the ninth or tenth aspect, wherein the nonwoven fabric is made of two or more materials having different melting points.

[0026] The method for producing a coated molded product according to the thirteenth aspect may be the same as the tenth or eleventh aspect, in which, in the step of injection molding a primary resin into a molding cavity, part or all of the material of the nonwoven fabric having a relatively low melting point dissolves between the fibers of the other nonwoven fabric as the fiber shape is deformed and melts, filling some of the gaps in the nonwoven fabric and smoothing the surface of the nonwoven fabric.

[0027] The method for producing a painted molded product according to the fourteenth aspect may be the same core mold as the core mold for the primary resin molding and the core mold for the paint film in either of the tenth or eleventh aspects.

[0028] The method for producing a painted molded product according to the fifteenth aspect is the same as the fourteenth aspect, in which the cavity mold for primary resin molding and the cavity mold for paint film may be capable of changing their positions by sliding or rotating.

[0029] The method for producing a painted molded product according to the sixteenth aspect may be the same as the tenth or eleventh aspect, in which a cavity mold is used as both the cavity mold for the primary resin molding and the cavity mold for the paint film, and the cavity mold is moved to define a paint cavity between the nonwoven fabric and the cavity mold by leaving a gap between the nonwoven fabric and the cavity mold.

[0030] A coated molded article and a method for manufacturing the same according to an embodiment of the present disclosure will be described below with reference to the accompanying drawings. In the drawings, identical components are designated by the same reference numerals.

[0031] (Embodiment 1) <Coated Molded Product> Figure 5A is a schematic cross-sectional view showing the cross-sectional structure of coated molded product 20 according to embodiment 1. Figure 5B is an enlarged cross-sectional view of portion A in Figure 5A. Coated molded product 20 according to embodiment 1 includes shaped nonwoven fabric 10, solidified primary resin 12 applied to one side of nonwoven fabric 10, and coating film 14 made of reactive paint applied to the other side of nonwoven fabric 10. According to coated molded product 20 according to embodiment 1, primary resin 12 penetrates into gaps in the mesh structure on back side 13 of nonwoven fabric 10, providing an anchor effect, and coating film 14 made of reactive paint adheres to front side 11 of nonwoven fabric 10. This improves adhesion between primary resin 12 and coating film 14 via nonwoven fabric 10. Specifically, by using nonwoven fabric 10, unlike the method of providing a grained pattern on the surface of primary resin 12, the voids inside the nonwoven fabric have an undercut structure, which makes it possible to obtain a strong anchor effect between primary resin 12 and coating film 14. For example, in a nonwoven fabric originally having a thickness of 0.25 mm, the thickness of a nonwoven fabric containing no low-melting point component is 0.25 mm, whereas the thickness of a nonwoven fabric containing a low-melting point component is thinned and smoothed to about 0.1 mm.

[0032] Each of the components that make up this painted molded product will be described below.

[0033] <Nonwoven Fabric> The nonwoven fabric contains two types of materials with different melting points: a relatively low-melting-point material and a high-melting-point material. The blending ratio of the low-melting-point material to the total nonwoven fabric (100% by weight) is, for example, in the range of 10% by weight or more and 90% by weight or less. By making it 10% by weight or more, the low-melting-point material melts, making it easier to smooth the nonwoven fabric and reducing the likelihood of nonwoven fabric fuzz appearing on the surface of the paint film. By making it 90% by weight or less, excessive melting of the nonwoven fabric on the surface of the primary resin is suppressed, ensuring an undercut structure sufficient for bonding with the paint and achieving sufficient adhesion. Note that the melting point of the low-melting-point material is, for example, lower than that of the primary resin. On the other hand, a material with a higher melting point than that of the primary resin may be used.

[0034] For example, when the nonwoven fabric is made of polyethylene terephthalate, it may be made of polyethylene terephthalate staple fibers with an average fineness of 0.6 to 3.3 dtex (decitex) and heat-fusible polyester staple fibers with a core-sheath structure containing a low-melting point component, in a weight ratio of 10 / 90 to 90 / 10 (Example 1).

[0035] In the manufacturing process of the nonwoven fabric, fibers spun from a carding machine are folded obliquely crosswise to form a web, and after entangling the fibers using a needle punch machine, the heat-fusible polyester staple fibers are melted in a heat treatment device to form a nonwoven fabric sheet. The heat-fusible polyester staple fibers having a core-sheath structure are composite fibers having a core-sheath structure in which the core is made of polyethylene terephthalate, a material with a high melting point, and the sheath is made of a copolymer polyester, a material with a low melting point. The melting point of the low-melting-point material of the sheath in the heat-fusible polyester staple fibers is preferably in the range of 100°C to 160°C so that molding can be performed even at a relatively low mold temperature.

[0036] Furthermore, the nonwoven fabric forms a multilayer structure in which each layer can deform in the shear direction. This allows the nonwoven fabric layers to deform in the shear direction against each other during tensile and compressive deformation during hot press processing, thereby acting as a buffer and suppressing wrinkling and tearing in molded products containing the nonwoven fabric. The number of layers in the multilayer structure is preferably 5 to 30. If the number of layers is less than 5, the range of shear deformation is narrowed, reducing the effectiveness in preventing wrinkling and tearing in molded products. On the other hand, if the number of layers is more than 30, the molded product itself becomes too thick, resulting in large circumferential differences during bending, making it difficult to adequately conform to the product shape. Considering the effectiveness against wrinkling and tearing and bending processability, the number of layers in the multilayer structure is more preferably 10 to 20. However, the number of layers in the multilayer structure is not limited as long as the above-mentioned effects are obtained.

[0037] When the nonwoven fabric is heat-pressed, the copolymer polyester, which is a low-melting material in the sheath portion of the heat-fusible polyester staple fibers 21 having a core-sheath structure, is thermally melted and fused to other heat-fusible polyester staple fibers or polyethylene terephthalate staple fibers to form a crosslinked structure. Note that, in the entire nonwoven fabric, it is not necessary for all of the copolymer polyester, which is a low-melting material, to be thermally melted, and fused portions and non-fused portions may exist.

[0038] Furthermore, the weight ratio of fibers used in the nonwoven fabric described above in Example 1 is, for example, polyethylene terephthalate staple fiber / core-sheath-bondable polyester staple fiber = 10 / 90 to 90 / 10, and more preferably 30 / 70 to 70 / 30. When the weight ratio of the core-sheath-bondable polyester staple fiber is within the above range, the texture maintains a moderate hardness, good mold conformability, and sufficient molding precision can be obtained. Furthermore, since the processing temperature in the heat treatment device also affects the texture of the nonwoven fabric, processing at 100°C to 160°C is preferred, but as long as good mold conformability and sufficient molding precision can be obtained, the processing temperature is not necessarily limited to this range.

[0039] In Example 1, a hybrid combination of polyethylene terephthalate staple fibers, which are a high-melting-point material, and heat-fusible polyester staple fibers having a sheath-core structure, including a core made of a high-melting-point material and a sheath made of a low-melting-point material, was described as a polyethylene terephthalate-based material. However, the present invention is not limited to this. The heat-fusible polyester staple fibers having a sheath-core structure are so-called composite fibers that include a high-melting-point material and a low-melting-point material in a single fiber. The fibers contained in the nonwoven fabric may be a combination of a basic low-melting-point material and a high-melting-point material, rather than a composite fiber having a sheath-core structure. As described above, the material and structure may be selected according to the application. For example, nylon, polypropylene, polyethylene-based fibers, etc. may be used as raw materials, or different raw materials may be used in combination. Furthermore, the fiber structure of the composite fiber may be formed into an island-sea structure or a side-by-side structure instead of a sheath-core structure. Furthermore, a combination of multiple types of composite fibers may be used. Furthermore, the method of thermocompression bonding is not limited as long as it can improve the strength of the coated molded article itself and allow the coated molded article to maintain its predetermined processed shape.

[0040] <Primary Resin> The primary resin may be any resin that can be used in injection molding. For example, the primary resin may be ABS, polycarbonate (PC), or ABS, as well as poorly adhesive resins such as polypropylene (PP), polyphenylene sulfide (PPS), and polystyrene (PS). Furthermore, materials that contribute to improving the physical properties of the primary resin material, such as glass fiber, cellulose fiber, and carbon fiber, may be added to the above resins. Furthermore, other materials that contribute to improving the physical properties of the primary resin material may be added, without being limited to the above materials. Furthermore, the primary resin may contain waste materials (e.g., coffee grounds, wood powder, and inorganic waste materials) that are used in recent environmentally friendly projects to reduce the use of petroleum-derived resin materials. It may also be a recycled resin containing multiple primary resin materials. There are no particular restrictions on the primary resin used.

[0041] <Coating film> The coating film may have a grain or texture on the surface opposite to the primary resin side. The grain or texture can make the nonwoven fabric below the coating film less visible. The thickness of the coating film may be 70 μm or more. It may also be 100 μm or more. It may also be 400 μm or more. The coating film is formed by curing a reactive paint.

[0042] <Reactive Paint> Any reactive paint commonly used in in-mold coating can be used. The reactive paint may be, for example, a two-component mixed type. In this case, the base agent may be, for example, a polyol, and the curing agent may be, for example, an isocyanate. The reactive paint may also contain a dye or a pigment.

[0043] <Method for manufacturing a coated molded article> Fig. 1 is a flowchart of a method for manufacturing a coated molded article according to embodiment 1. Fig. 2A is a specific flowchart of a series of steps S01 for obtaining the resin molded article of Fig. 1. Fig. 2B is a specific flowchart of a series of steps S02 for obtaining the coated molded article of Fig. 1. As shown in Fig. 1, the method for manufacturing a coated molded article according to embodiment 1 includes a series of steps S01 for obtaining a resin molded article by injection molding a primary resin onto one surface of nonwoven fabric 10, and a series of steps S02 for filling the other surface of nonwoven fabric 10 with a reactive paint to obtain a coated molded article on which a coating film made of the reactive paint is formed. As shown in FIG. 2A, the series of steps S01 for obtaining a resin molded product includes a step S11 of clamping the primary resin molding core mold 24, which has nonwoven fabric 10 arranged on the surface facing the primary resin molding core mold, with the primary resin molding cavity mold 24; a step S12 of injection molding primary resin 2 into a molding cavity 25 defined between the primary resin molding core mold 22 and the nonwoven fabric 10 arranged in the primary resin molding cavity mold 24; and a step S13 of opening the primary resin molding core mold 22 and the primary resin molding cavity mold 24 to obtain a resin molded product 18 having nonwoven fabric 10 on the surface of the solidified primary resin 12. The series of steps S02 for obtaining a coated molded product includes a step S21 of clamping the core mold 22 for the paint film in which the resin molded product is placed and the cavity mold 26 for the paint film together, a step S22 of filling the paint cavity 27 defined between the nonwoven fabric 10 of the resin molded product and the cavity mold 26 for the paint film with reactive paint 4 to form a coating film 14 made of the reactive paint on the nonwoven fabric 10, and a step S23 of opening the core mold 22 for the paint film and the cavity mold 26 for the paint film to obtain a coated molded product 20 having the nonwoven fabric 10, solidified primary resin 12 provided on one side of the nonwoven fabric 10, and the coating film 14 provided on the other side of the nonwoven fabric 10.

[0044] <Series of steps for obtaining a resin molded product> As shown in Figure 2A, the series of steps S01 for obtaining a resin molded product includes the following steps: (1) A primary resin molding cavity mold 24, on the surface facing the primary resin molding core mold 22, is clamped together with the primary resin molding core mold 22 (S11, Figure 3A). (2) A primary resin 2 is injection molded into a molding cavity 25 defined between the primary resin molding core mold 22 and the nonwoven fabric 10 placed in the primary resin molding cavity mold 24 (S12, Figure 3B). (3) The primary resin molding core mold 22 and the primary resin molding cavity mold 24 are opened to obtain a resin molded product 18 having nonwoven fabric 10 on the surface of the solidified primary resin 12 (S13, Figure 3C).

[0045] Before injection molding the primary resin, a nonwoven fabric made of a polyester alloy resin is set in the mold in the coating area, and molten primary resin 2 is injected into the molding cavity 25 in the mold. This causes a portion of the primary resin 2 to penetrate into the back side of the nonwoven fabric 10, creating an anchor effect for adhesion. Furthermore, the front side of the nonwoven fabric 10 opposite the primary resin 2 is smoothed by the injection pressure.

[0046] <Series of steps for obtaining a coated molded product> As shown in Figure 2B, the series of steps S02 for obtaining a coated molded product includes the following steps: (4) The core mold 22 for a paint film, in which the resin molded product is placed, is clamped together with the cavity mold 26 for a paint film (S21, Figure 4A). A paint cavity 27 is defined between the nonwoven fabric 10 of the resin molded product and the cavity mold 26 for a paint film. (5) The reactive paint 4 is filled into the paint cavity 27 defined between the nonwoven fabric 10 of the resin molded product and the cavity mold 26 for a paint film, and a paint film made of the reactive paint 4 is formed on the nonwoven fabric 10 (S22, Figure 4B). (6) The core mold 22 for the coating film and the cavity mold 26 for the coating film are opened to obtain a coated molded product 20 having the nonwoven fabric 10, the solidified primary resin 12 provided on one side of the nonwoven fabric 10, and the coating film 14 provided on the other side of the nonwoven fabric 10 (S23, Figure 4C).

[0047] In the series of processes for obtaining a coated molded product, for example, a die slide (DSI) mold may be used to slide the primary resin molding cavity mold 24 into the coating film cavity mold 26. In this case, the primary resin molding core mold used to produce the resin molded product and the coating film core mold used to produce the coated molded product may be a common core mold. This defines a coating cavity 27 between the surface of the nonwoven fabric 10 on the surface of the primary resin 12 placed in the core mold 22 and the coating film cavity mold 26. A highly fluid reactive paint 4 is poured into this coating cavity 27. This allows the reactive paint 4 to flow onto the surface side of the nonwoven fabric 10, penetrating the gaps in the mesh structure of the nonwoven fabric 10, thereby creating an anchor effect that bonds the coating film 14 formed by the reactive paint 4 to the nonwoven fabric layer 10. This allows the poorly adhesive primary resin 12 and the coating film 14 made of reactive paint for in-mold coating to adhere via the nonwoven fabric 10, making it possible to adhere the primary resin and the coating film together regardless of the type of primary resin.

[0048] Furthermore, a common cavity mold may be used for both the primary resin molding and the coating film. In this case, the cavity mold may be moved to define a coating cavity between the nonwoven fabric and the cavity mold by leaving a gap between the nonwoven fabric and the cavity mold. The cavity mold may be movable, for example, by having a movable nesting structure.

[0049] <Regarding the nonwoven fabric> For example, a nonwoven fabric containing a low-melting point and a high-melting point (regular) polyester resin is used. As a result, during injection molding of the primary resin, part or all of the low-melting point polyester resin melts and dissolves into the nonwoven fabric between the nonwoven fabric made of the high-melting point polyester resin (regular nonwoven fabric), making the nonwoven fabric itself thin and forming a smooth surface. If only a normal high-melting point (regular) nonwoven fabric is used, the surface of the nonwoven fabric opposite the primary resin will remain fuzzy even after injection molding, and when a reactive paint for in-mold coating is poured in, pilling may appear on part of the surface of the coating film, reducing the appearance quality of the coating film surface.

[0050] The nonwoven fabric may be one having a color similar to that of the primary resin. This makes it possible to make the color of the nonwoven fabric difficult to see when viewed from the surface of the coating film after in-mold coating. Note that nonwoven fabric does not need to be provided in areas where a coating film is not provided. In other words, nonwoven fabric is provided in areas that will be the underlying layer of the coating film where it is provided.

[0051] The reactive paint for in-mold coating may contain a dye or pigment of a desired color, which makes it difficult to see the nonwoven fabric behind the coating film when viewed from the coating surface of the coated molded article, thereby producing a high-quality coated molded article.

[0052] The surface of the coating film may be provided with a design-oriented grain or texture, which makes the shape and pattern of the grain or texture on the surface of the coating film more easily recognizable and makes it more difficult to visually recognize the nonwoven fabric underneath the coating film, making it easier to obtain a high-quality coated molded product.

[0053] When it is desired to paint the back surface of a coated molded product, the nonwoven fabric may be preformed into a complex three-dimensional product shape using press molding or vacuum / pressure molding, etc. The shaped nonwoven fabric is then set in a die-slide mold, a primary resin is molded, the shaped nonwoven fabric is formed into the surface that will be coated with the primary resin, and then a reactive paint is poured onto the surface of the shaped nonwoven fabric to obtain a coated molded product. Alternatively, a mold for integrating the nonwoven fabric and the primary resin and a mold for pouring the reactive paint onto the surface of the nonwoven fabric opposite the primary resin may be separately processed in separate processes. Alternatively, the mold for integrating the nonwoven fabric and the primary resin and the mold for pouring the reactive paint onto the surface of the nonwoven fabric opposite the primary resin may be continuously processed using a common mold.

[0054] The surface roughness of the nonwoven fabric at the interface with the coating film may be smoother than the surface roughness of the interface with the primary resin. As described above, as shown in FIG. 5B , when the primary resin 12 is injection molded on the back side 13 of the nonwoven fabric, the primary resin 12 penetrates into the gaps in the mesh structure of the back side 13 of the nonwoven fabric 10, creating an anchor effect, and the coating film 14 made of reactive paint adheres to the front side 11 of the nonwoven fabric 10. Note that the front side 11 of the nonwoven fabric 10 is smoothed by the injection pressure of the primary resin. In other words, the front side of the nonwoven fabric may be smoother than the back side.

[0055] According to the method for manufacturing a coated molded product of the first embodiment, a nonwoven fabric is used to form undercut structures at the interface between the primary resin and the nonwoven fabric, and at the interface between the paint film and the nonwoven fabric, thereby physically bonding the primary resin and the paint via the nonwoven fabric. This method for manufacturing a coated molded product does not require additional capital investment for ozone generators or ozone recovery. Furthermore, even when the primary resin is changed, coated molded products can be produced at low cost using the same reactive paint, without changing the type of primer or paint to match the type of primary resin. In other words, the series of processes of ozone injection, ozone corrosion, and ozone recovery is unnecessary, shortening the manufacturing takt time and enabling the production of coated molded products using in-mold coating with high productivity.

[0056] Example 1 Figure 6A is a schematic cross-sectional view showing the cross-sectional structure of a coated molded article 20a according to Example 1. Figure 6B shows a 50x magnification photograph (a) and a 200x magnification photograph (b) of the coating film surface of the coated molded article 20a according to Example 1. Figure 6C is a 200x magnification cross-sectional photograph showing the cross-sectional structure of the coated molded article 20a according to Example 1. The coated molded article 20a according to Example 1 has a nonwoven fabric 10 containing a high-melting-point material and a low-melting-point material in a weight ratio of 60:40. As shown in the schematic cross-sectional view of Figure 6A, when a primary resin (polypropylene: PP or polyphenylene sulfide: PPS) 12 is injection molded onto the back side of the nonwoven fabric 10, the low-melting-point material is partially melted, smoothed, and thinned to a thickness of approximately 0.1 mm. Therefore, no naps due to the nonwoven fabric 10 are observed in the enlarged photograph of the coating film surface in Figure 6B. 6C, no naps were observed from the nonwoven fabric 10 to the coating film 14. The adhesion between the coating film 14 and the primary resin 12 was good.

[0057] (Comparative Example 1) Figure 7A is a schematic cross-sectional view showing the cross-sectional structure of a coated molded article 50 according to Comparative Example 1. Figure 7B is a 50x optical magnification photograph (a) and a 200x optical magnification photograph (b) of the coating film surface of the coated molded article 50 according to Comparative Example 1. Figure 7C is a 200x optical magnification cross-sectional photograph showing the cross-sectional structure of the coated molded article 50 according to Comparative Example 1. The coated molded article 50 according to Comparative Example 1 has a weight ratio of high-melting point material:low-melting point material in the nonwoven fabric 10 of 100:0, i.e., is composed only of high-melting point material and does not contain any low-melting point material. As shown in the schematic cross-sectional view of Figure 7A, when the primary resin (polypropylene: PP or polyphenylene sulfide: PPS) 12 is injection molded onto the back side of the nonwoven fabric 10, the nonwoven fabric does not contain a low-melting-point material. Therefore, some of the nonwoven fabric is not smoothed sufficiently, and some of the naps of the nonwoven fabric are not completely flattened, resulting in naps (fibers) 15 protruding from the surface of the coating film, with a thickness of approximately 0.25 mm. Therefore, numerous naps 15 originating from the nonwoven fabric 10 are observed in the enlarged photograph of the coating film surface of Figure 7B. Furthermore, numerous naps 15 extending from the nonwoven fabric 10 to the coating film 14 are also observed in the cross-sectional photograph of Figure 7C at 200x optical magnification. Furthermore, the adhesion between the coating film 14 and the primary resin 12 was good.

[0058] Comparing Example 1 and Comparative Example 1, in both cases, adhesion between the coating film 14 and the primary resin 12 was good due to the presence of the nonwoven fabric 10. On the other hand, in Comparative Example 1, in which the nonwoven fabric 10 did not contain a low-melting-point material, numerous naps 15 caused by the nonwoven fabric 10 were observed on the surface of the coating film. In contrast, in Example 1, in which the nonwoven fabric contained 40% by weight of a low-melting-point material, no naps were observed on the surface of the coating film. This shows that by including a low-melting-point material in the nonwoven fabric, when the primary resin (polypropylene: PP or polyphenylene sulfide: PPS) 12 is injection molded on the back side of the nonwoven fabric 10, the low-melting-point material is partially melted, smoothed, and thinned, thereby suppressing the generation of naps on the coating film side.

[0059] The coated molded article and manufacturing method thereof according to the present disclosure can bond the primary resin and the paint via the nonwoven fabric, eliminating the need to use corrosive gases such as ozone and to optimize the paint composition or primer composition for the primary resin.

[0060] 2 Primary resin (molten state) 4 Reactive paint 10 Nonwoven fabric 11 Front side 12 Primary resin (after solidification) 13 Back side 14 Coating film 15 Raised nonwoven fabric 18 Resin molded product 20 Coated molded product 20a Coated molded product (Example 1) 22 Core mold 24 Cavity mold for primary resin molding 25 Molding cavity 26 Cavity mold for coating film 27 Coating cavity 50 Coated molded product (Comparative example 1)

Claims

1. A coated molded product comprising: a nonwoven fabric; a solidified primary resin provided on one side of the nonwoven fabric; and a coating film made of a reactive paint provided on the other side of the nonwoven fabric.

2. The coated molded product according to claim 1, wherein the nonwoven fabric is made of two or more materials with different melting points.

3. The coated molded product according to claim 2, wherein the nonwoven fabric is such that part or all of the material with a relatively low melting point dissolves between the other fibers of the nonwoven fabric as the fiber shape changes and melts, filling some of the gaps in the nonwoven fabric and smoothing the surface of the nonwoven fabric.

4. A coated molded product according to any one of claims 1 to 3, wherein the nonwoven fabric is of a color similar to that of the primary resin.

5. The coated molded product according to any one of claims 1 to 3, wherein the reactive paint contains a dye or a pigment.

6. A coated molded product according to any one of claims 1 to 3, wherein the coating film has a grain or texture on the surface opposite to the primary resin side.

7. A coated molded product according to any one of claims 1 to 3, wherein the surface roughness of the interface between the nonwoven fabric and the coating film is smoother than the surface roughness of the interface between the nonwoven fabric and the primary resin.

8. A coated molded product according to any one of claims 1 to 3, wherein the thickness of the coating film is 70 μm or more.

9. A method for manufacturing a coated molded product, comprising: a step of preparing a resin molded product having a nonwoven fabric on the surface of a primary resin; a step of clamping a core mold for a paint film in which the resin molded product is placed and a cavity mold for a paint film; a step of filling a paint cavity defined between the nonwoven fabric of the resin molded product and the cavity mold for a paint film with a reactive paint to form a paint film made of the reactive paint on the nonwoven fabric; and a step of opening the core mold for a paint film and the cavity mold for a paint film to obtain a coated molded product having the nonwoven fabric, the solidified primary resin provided on one side of the nonwoven fabric, and the paint film provided on the other side of the nonwoven fabric.

10. A method for manufacturing a coated molded product according to claim 9, wherein the step of preparing a resin molded product having a nonwoven fabric on the surface of the primary resin comprises: a step of clamping a cavity mold for primary resin molding, having a nonwoven fabric arranged on the surface facing the core mold for primary resin molding, and the core mold for primary resin molding; a step of injection molding a primary resin into a molding cavity defined between the core mold for primary resin molding and the nonwoven fabric arranged in the cavity mold for primary resin molding; and a step of opening the core mold for primary resin molding and the cavity mold for primary resin molding to obtain a resin molded product having the nonwoven fabric on the surface of the solidified primary resin.

11. A method for producing a coated molded product according to claim 10, comprising a step of shaping or smoothing the surface of the nonwoven fabric before placing the nonwoven fabric in the core mold for primary resin molding.

12. The method for producing a coated molded product according to claim 9 or 10, wherein the nonwoven fabric is made of two or more materials with different melting points.

13. A method for producing a coated molded product as described in claim 10 or 11, wherein, in the step of injection molding the primary resin into the molding cavity, part or all of the material with a relatively low melting point of the nonwoven fabric dissolves between the other fibers of the nonwoven fabric as the fiber shape changes and melts, filling some of the gaps in the nonwoven fabric and smoothing the surface of the nonwoven fabric.

14. The method for producing a painted molded product according to claim 10 or 11, wherein the core mold for the primary resin molding and the core mold for the paint film are a common core mold.

15. A method for producing a coated molded product according to claim 14, wherein the positions of the cavity mold for primary resin molding and the cavity mold for coating film can be changed by sliding or rotating.

16. A method for producing a coated molded product as described in claim 10, wherein a common cavity mold is used as both the cavity mold for the primary resin molding and the cavity mold for the coating film, and the cavity mold is moved to define the coating cavity between the nonwoven fabric and the cavity mold by leaving a gap between the nonwoven fabric and the cavity mold.

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