Method for manufacturing painted objects and method for treating painted edges

Abstract

This invention provides a method for manufacturing painted products that can stably produce painted products with excellent aesthetic appeal, reduce man-hours, shorten cycle times, reduce environmental impact, and suppress defects such as blistering. [Solution] A method for manufacturing a painted object, comprising: applying masking by placing a masking material on a part of the surface of the object to be painted; applying a first paint to the painted area on the surface of the object to be painted, excluding the masking area, extending beyond the boundary between the painted area and the masking area to the masking area to form a first paint film; removing the masking material when the first paint film is touch dry; applying a second paint to the surface of the object from which the masking material has been removed, so as to cover at least the boundary, to form a second paint film; and heating and curing the first paint film and the second paint film.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a painted object and a method for treating a painting cut-off part.

Background Art

[0002] For example, when performing two-color painting using two types of paints and it is necessary to partially paint the surface of the object to be painted, generally, masking is performed by arranging a masking material in the non-painted area along the boundary between the painted area and the non-painted area, and then painting is carried out.

[0003] Patent Document 1 discloses a painting method in which a diluted solvent mixed with the first-color paint is sprayed on the second-color painting range near the cut-off line between the first-color painting range and the second-color painting range, the first-color painting range is painted with the first-color paint, and after masking the first-color painting range, the second-color painting range is painted with the second-color paint. Patent Document 2 discloses a painting method in which the first paint is painted on the surface of the object to be painted to form a semi-dry first-color coating layer, a part of the first-color coating layer is masked, and then the second paint is painted to form a second-color coating layer, and the first-color coating layer and the second-color coating layer are cured.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in conventional methods such as those of Patent Documents 1 and 2, there may occur problems such as a part of the paint peeling off at the cut-off part and the base being visible. Furthermore, in painting, it is necessary to reduce the number of steps and shorten the cycle time as much as possible. It is also important to conserve resources by reducing the amount of paint used and to reduce the environmental impact by reducing energy consumption. In addition, if paint is heat-cured while masking is performed with masking tape, the adhesive of the masking tape may adhere to the surface of the object to be painted due to the effects of the solvent contained in the paint. If the removal of this adhesive is insufficient, blistering may occur after the top clear coat is applied.

[0006] The main objective of the present invention is to provide a method for manufacturing painted products and a method for treating painted edges that can stably produce painted products with excellent design, reduce man-hours, shorten cycle times, reduce environmental impact, and suppress defects such as blistering. [Means for solving the problem]

[0007] The present invention includes the following configuration. [1] A method for manufacturing a painted object, comprising partially applying a first paint to the surface of an object to be painted, and then applying a second paint to obtain the painted object, Masking is performed by placing masking material on a part of the surface of the object to be painted, To form a first coating film by applying the first paint to the coating area on the surface of the object to be coated, excluding the masking area, and extending the first paint beyond the boundary between the coating area and the masking area up to the masking area, The masking material is removed while the first coating film is touch-dry, The process involves applying a second paint to the surface of the object to be painted, from which the masking material has been removed, so as to cover at least the trimmed portion, thereby forming a second paint film. A method for manufacturing a painted product, comprising heating and curing the first coating film and the second coating film. [2] The method for manufacturing a coated product according to [1], wherein the first coating film is touch-dry at 50°C or below, and the first coating film and the second coating film are cured at 60°C or above. [3] The method for manufacturing a painted article according to [1] or [2], wherein the first paint is a colored paint and the second paint is a transparent or translucent paint. [4] A method for manufacturing a painted product according to any one of [1] to [3], wherein the thickness of the first coating film in a touch-dry state is less than the thickness of the masking material. [5] A method for manufacturing a coated product according to any one of [1] to [4], wherein the thickness of the second coating film before heat curing is 1.5 to 3.0 times the thickness of the first coating film. [6] A method for manufacturing a coated product according to any one of [1] to [5], wherein the thickness of the second coating film after heat curing is 50 to 80 μm. [7] The object to be painted has steps on the surface to be painted, A method for manufacturing a painted object according to any one of [1] to [6], wherein masking is applied to the lower surface of the step on the surface of the object to be painted so that the trim portion follows the inner corner of the step, and the first paint is applied to the upper surface of the step. [8] A method for manufacturing a painted product according to any one of [1] to [7], wherein the second coating film is only one layer. [9] A method for manufacturing a painted product according to any one of [1] to [8], wherein the first paint is a two-component paint.

[10] Masking is performed by placing a masking material on a part of the surface of the object to be painted, To form a colored coating film on the surface of the object to be painted, by applying colored paint to the painted area other than the masking area, extending beyond the boundary between the painted area and the masking area up to the masking area, The masking material is removed when the colored coating is touch-dry, On the surface of the object to be painted from which the masking material has been removed, a clear or translucent paint is applied to cover at least the trimmed area to form a clear coating. A method for treating a painted edge, comprising heating and curing the colored coating and the clear coating. [Effects of the Invention]

[0008] According to the present invention, a coating with excellent designability can be stably obtained, and it is possible to reduce man-hours, shorten cycle time, reduce environmental impact, and suppress defects such as blisters. A method for manufacturing a coating and a method for treating a coating cut-off portion are provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic cross-sectional view for explaining an example of step (i) according to an embodiment. [Figure 2] It is a schematic cross-sectional view for explaining an example of step (ii) according to an embodiment. [Figure 3] It is a schematic cross-sectional view for explaining an example of step (ii) according to an embodiment. [Figure 4] It is a schematic cross-sectional view for explaining an example of step (iv) according to an embodiment. [Figure 5] It is a schematic cross-sectional view for explaining an example of step (i) according to another example of an embodiment. [Figure 6] It is a schematic cross-sectional view for explaining an example of step (ii) according to another example of an embodiment. [Figure 7] It is a schematic cross-sectional view for explaining an example of step (ii) according to another example of an embodiment. [Figure 8] It is a schematic cross-sectional view for explaining an example of step (iv) according to another example of an embodiment. [Figure 9] It is a photograph of the cut-off portion of the coating obtained in Example 1 taken from the second coating film side. [Figure 10] It is a photograph of the cut-off portion of the coating obtained in Comparative Example 1 taken from the top clear side.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a method for manufacturing a coating according to an embodiment will be described with reference to the drawings. In the following description, the dimensions and the like of the figures exemplified are merely examples, and the present invention is not necessarily limited thereto, and it can be appropriately changed and implemented within the range not changing the gist thereof.

[0011] [Method of manufacturing painted objects] The method for manufacturing a painted product according to the embodiment is a method for obtaining a painted product by partially applying a first paint to the surface of a workpiece and then applying a second paint, and includes the following (i) to (v). (i) Applying masking by placing masking material on a portion of the surface of the object to be painted. (ii) Applying the first paint to the painted area on the surface of the object to be painted, excluding the masking area, beyond the boundary between the painted area and the masking area, up to the masking area, thereby forming a first paint film. (iii) Remove the masking material after the first coating film has been allowed to dry to the touch. (iv) Applying a second paint to the surface of the object to be painted from which the masking material has been removed, so as to cover at least the trimmed portion, thereby forming a second paint film. (v) Heating and curing the first coating film and the second coating film.

[0012] <Object to be painted> The objects to be painted are not particularly limited and include, for example, the bodies and exterior panels of automobiles, motorcycles, etc., and the exteriors of electrical products. The shape of the object to be painted is not particularly limited; it may be flat or have a three-dimensional shape depending on its application. The object to be painted may have a base coat, clear coat, or other surface treatment applied to the substrate.

[0013] The materials constituting the object to be painted are not particularly limited, and examples include metal materials such as steel, and fiber-reinforced composite materials (FRP) containing a reinforcing fiber base material and a matrix resin. Examples of reinforcing fiber base materials include UD sheets (unidirectional sheets) in which multiple reinforcing fibers are aligned in one direction, cloth materials made by weaving reinforcing fibers into fabrics, and nonwoven fabrics. From the viewpoint of design, cloth materials are preferred. The cloth material may be a cloth material with any weave structure, such as a unidirectional fabric in which reinforcing fibers are arranged in the required direction, a bidirectional fabric such as plain weave, satin weave, or twill weave, or a triaxial weave or non-crimped fabric. The reinforcing fiber base material used in the fiber-reinforced composite material may be one type or two or more types.

[0014] Examples of reinforcing fibers include carbon fibers, aramid fibers, silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide fibers, and glass fibers. In the case of a painted object made of a fiber-reinforced composite material, carbon fiber reinforced composite material (CFRP) using carbon fibers as reinforcing fibers is preferred due to its superior specific strength, specific modulus of elasticity, and design. The reinforcing fibers used in the reinforcing fiber base material may be one type or two or more types.

[0015] The matrix resin may be a thermosetting resin or a thermoplastic resin. Thermosetting resins are preferred because they readily exhibit mechanical properties. Examples of thermosetting resins include epoxy resins, phenolic resins, unsaturated polyester resins, urethane resins, and urea resins. The matrix resin used in the fiber-reinforced composite material may be one type or two or more types. The matrix resin may contain additives such as flame retardants, weathering modifiers, antioxidants, heat stabilizers, UV absorbers, plasticizers, lubricants, colorants, compatibilizers, non-fibrous fillers, conductive fillers, mold release agents, and surfactants, as needed.

[0016] <Paint> The first and second coatings used in this invention are not particularly limited. The first and second coatings may each be one-component or two-component. The first and second paints are different from each other, and both may be colored paints, or one may be a colored paint and the other a transparent or translucent paint. For example, if the object to be painted is CFRP, the aesthetic appeal of the painted object can be enhanced by making one of the first and second paints a transparent or translucent paint, allowing the CFRP to be partially visible from the outside. Typically, a colored paint can be used as the first paint and a transparent or translucent paint as the second paint, but this is not limited to this.

[0017] As for colored paints, various paints that can be used as a color base for topcoats can be used, and film-forming resin components, hardeners, pigments, and solvents may be incorporated. Examples of resin components include resins having functional groups, such as acrylic resins, vinyl resins, polyester resins, alkyd resins, and urethane resins. Examples of functional groups include hydroxyl groups, carboxyl groups, silicon-containing groups, epoxy groups, and potentially blocked isocyanate groups. The resin components contained in the paint may be one type or two or more types.

[0018] Examples of curing agents include melamine resins, urea resins, polyisocyanate compounds (which may be blocked), carboxyl group-containing compounds, and epoxy group-containing compounds that react with functional groups in the resin component. The paint may contain one or more curing agents.

[0019] Examples of pigments include black pigments, blue pigments, and red pigments. Examples of black pigments include carbon black, acetylene black, lamp black, bone black, graphite, black iron oxide (iron(II,III) oxide), black titanium oxide, copper manganese black, copper chromium black, cobalt black, cyanine black, and aniline black. Examples of blue pigments include phthalocyanine-based pigments, indanthrone-based pigments, and indigo-based pigments. Examples of red pigments include azo pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, and iron oxides. The paint may contain one type of pigment or two or more types.

[0020] Examples of solvents include water, aromatic solvents, aliphatic solvents, ester solvents, ketone solvents, and alcohol solvents. Examples of aromatic solvents include xylene. Examples of aliphatic solvents include mineral spirits. Examples of ester solvents include ethyl acetate, butyl acetate, propyl propionate, butyl propionate, 1-methoxy-2-propyl acetate, 2-ethoxyethyl propionate, 3-methoxybutyl acetate, ethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate. Examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone. Examples of alcohol-based solvents include isopropanol, n-butanol, isobutanol, and 2-ethylhexanol. The paint may contain one type of solvent, or two or more types.

[0021] Colored paints may contain various additives such as viscosity modifiers, flow regulators, light stabilizers, UV absorbers, extender pigments, and pigment dispersants. The colored paint may be a colored clear paint obtained by adding pigment to a transparent or translucent paint. Known colored clear paints can be used, for example, paints obtained by dissolving or dispersing resin components such as acrylic resin, polyester resin, alkyd resin, urethane resin, and epoxy resin, a curing agent such as blocked polyisocyanate, melamine resin, and urea resin, a pigment, and additives as needed, in an organic solvent.

[0022] As for transparent or translucent paints, known clear paints can be used, such as paints in which a resin component such as acrylic resin, polyester resin, alkyd resin, urethane resin, or epoxy resin, a curing agent such as block polyisocyanate, melamine resin, or urea resin, and additives used as needed are dissolved or dispersed in an organic solvent.

[0023] The following explains each step using an example. <Process (i)> For example, as shown in Figure 1, masking is performed by placing a masking material 20 on a part of the surface 10a of the object to be painted 10. More specifically, the masking material 20 is placed along the boundary C between the painted area A and the masking area B on the masking area B of the surface 10a of the object to be painted 10, excluding the painted area A of the first paint. As the masking material 20, known materials can be used, such as masking tape and masking sheets.

[0024] In this example, the object to be painted 10 has a base material 11 made of CFRP, a primer layer 12 formed on the surface of the base material 11, and a clear coating 13 formed on the surface of the primer layer 12. The clear coating 13 is cured and dried. The object to be painted 10 is not limited to this form. The clear coating 13 may be a single layer or a multi-layered layer of two or more layers.

[0025] <Process (ii)> As shown in Figure 2, the first paint is applied to the painted area A on the surface 10a of the object to be painted, excluding the masking area B, and extends beyond the dividing line C between painted area A and masking area B to masking area B, thereby forming the first paint film 30. The method of applying the first paint is not particularly limited, and one example is to spray the first paint in a paint booth where the temperature and humidity are controlled.

[0026] The first paint is typically a desired colored paint, but is not limited to that. In step (iii) described later, when removing the masking material 20, it is preferable that the first paint be a two-component paint, as this makes it easier to suppress defects such as stringing of the first paint film 30. Furthermore, if a colored paint such as red, which is difficult to produce a vibrant color, is used as the first paint, a primer coat may be applied before the first paint to improve the color development.

[0027] <Step (iii)> As shown in Figure 3, the masking material 20 is removed when the first coating 30 is touch-dry. If the first coating 30 is hardened and dry when the masking material 20 is removed, the edge of the first coating 30 on the border C side will easily peel off following the masking material 20. In contrast, if the first coating 30 is touch-dry, the edge of the first coating 30 on the border C side will be less likely to curl up following the masking material 20 when the masking material 20 is removed, thus suppressing peeling. As a result, the appearance of the border C of the first coating 30 becomes cleaner.

[0028] In this invention, "touch-dry" refers to the state defined in JIS 5600-1-1:1999, where the center of the coated surface can be lightly touched with a fingertip without soiling the fingertip. The first coating film 30 in the touch-dry state is a state in which the first paint is uncured but does not flow, and there is no dripping of the first paint. In contrast, "cured dry" refers to the state in which the center of the coated surface can be firmly pinched between the thumb and index finger without leaving fingerprints on the surface, without feeling any movement of the coating film, and without leaving scratches on the surface when the center of the coated surface is rapidly and repeatedly rubbed with a fingertip. In the first coating film 30, which is in a touch-dry state, volatile components such as solvents have evaporated.

[0029] In the trim section C, it is preferable that the thickness D1 of the first coating film 30 in a touch-dry state is less than the thickness D2 of the masking material 20. This makes it even more difficult for the edge of the first coating film 30 on the trim section C side to peel off when the masking material 20 is removed. The ratio of D1 to D2 (D1 / D2) is preferably less than 1.0, more preferably 0.8 or less, even more preferably 0.5 or less, and particularly preferably 0.4 or less. Furthermore, in terms of the coating surface of the first coating film 30, D1 / D2 is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.4 or more. The preferred lower and upper limits of D1 / D2 can be arbitrarily combined.

[0030] The thickness D1 of the first coating film 30 in a touch-dry state is preferably 13 μm or more, more preferably 15 μm or more, even more preferably 17 μm or more, and particularly preferably 19 μm or more. If the thickness D1 is equal to or greater than the lower limit, the desired color tone can be achieved. The thickness D1 of the first coating film 30 in a touch-dry state is preferably 40 μm or less, more preferably 35 μm or less, even more preferably 30 μm or less, and particularly preferably 25 μm or less. If the thickness D1 is equal to or less than the upper limit, it is easy to smooth the transition step after applying the top clear coat. The preferred lower and upper limits of the thickness D1 can be arbitrarily combined. The thickness D1 of the first coating film 30 is determined as the average value of measurements taken at any three locations.

[0031] The thickness D2 of the masking material 20 is preferably 30 μm or more, more preferably 35 μm or more, even more preferably 40 μm or more, and particularly preferably 45 μm or more. If the thickness D2 is equal to or greater than the lower limit, the trim C can be painted to have a good appearance. The thickness D2 of the masking material 20 is preferably 90 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and particularly preferably 60 μm or less. If the thickness D2 is equal to or greater than the upper limit, the handling of the masking removal work will not be impaired. The preferred lower and upper limits of the thickness D2 can be arbitrarily combined. The thickness D2 of the masking material 20 is determined as the average value of measurements taken at any three locations.

[0032] A preferred method for drying the first coating 30 to a touch-dry state is to leave the first coating 30 standing in an environment of 50°C or lower. By allowing it to touch-dry at 50°C or lower, the adhesive of the masking material 20 is less likely to be affected by the solvent and adhere to the product, thus making it easier to suppress the occurrence of blisters after the top clear coat.

[0033] Whether the first coating film 30 is touch-dry can be confirmed, for example, by the following method. Another confirmation masking material is placed on top of a portion of the masking material 20, and when applying the first paint, the first paint is also applied to the confirmation masking material. The first paint film 30 is then checked to see if it is touch-dry by lightly touching the painted surface of the confirmation masking material with a fingertip to see if the fingertip gets dirty. With this method, it is not necessary to touch the painted surface of the first paint film 30, so fingerprints can be prevented from being left on the surface of the first paint film 30.

[0034] <Process (iv)> For example, as shown in Figure 4, the second paint is applied to the entire surface 10a of the object to be painted after the masking material 20 has been removed to form a second coating film 40. Note that the second paint only needs to be applied so as to cover at least the trim C, and is not limited to being applied to the entire surface 10a of the object to be painted. The method of applying the second paint is not particularly limited, and one example is to spray the second paint in a paint booth where the temperature and humidity are controlled.

[0035] The second coating is typically a transparent or translucent coating, but is not limited to that. The second coating 40 can be a single layer of clear coating (top clear). If the second coating 40 is only one layer, the amount of paint used can be reduced, contributing to cost reduction and reduced environmental impact. When the second coating 40 is a clear coating, the CFRP of the object to be coated 10 can be shown as an aesthetic feature in the areas where the first coating 30 is not applied when viewed from the painted surface side. As a second coating, a transparent or translucent coating may be applied to the entire surface 10a of the object to be coated 10 two or more times.

[0036] The thickness D3 of the second coating film 40 before heat curing, that is, the thickness D3 from the surface 10a of the workpiece 10 in a touch-dry state to the upper surface of the second coating film 40, is preferably 1.5 to 3.0 times the thickness D1 of the first coating film 30. If the ratio of the thickness D3 of the second coating film 40 to the thickness D1 of the first coating film 30 is within the above range, the step difference between the surface 10a of the workpiece 10 and the first coating film 30 at the border C is easily absorbed, and the surface of the second coating film 40 near the border C tends to become smoother. The ratio of the thickness D3 of the second coating film 40 to the thickness D1 of the first coating film 30 (D3 / D1) is preferably 1.5 or more, more preferably 2.0 or more, even more preferably 2.5 or more, and also preferably 3.0 or less, more preferably 2.8 or less, and even more preferably 2.6 or less. The preferred lower and upper limits of D3 / D1 can be any combination. The thickness D3 of the second coating 40 is determined as the average value of measurements taken at any three locations.

[0037] <Process (v)> In step (v), the first coating film 30 and the second coating film 40, both of which are uncured, are heat-cured (baked). The method for heat-curing the first coating film 30 and the second coating film 40 is not particularly limited and includes, for example, a method of heating them in a heating furnace or a method of heating them by applying hot air with a heat gun.

[0038] The heating temperature should be such that the first coating film 30 and the second coating film 40 are cured and dried, preferably 60°C or higher, more preferably 80°C or higher, even more preferably 95°C or higher, preferably 110°C or lower, and more preferably 105°C or lower. The preferred lower and upper limits of the heating temperature can be combined in any way. In the manufacturing method according to this embodiment, it is more preferable to dry the first coating film 30 to the touch at 50°C or below, and then cure the first coating film 30 and the second coating film 40 at 60°C or above.

[0039] The heat curing time is preferably 30 minutes or more, more preferably 40 minutes or more, even more preferably 50 minutes or more, and preferably 90 minutes or less, more preferably 80 minutes or less, and even more preferably 70 minutes or less. The preferred lower and upper limits of the heat curing time can be arbitrarily combined.

[0040] The thickness of the second coating film after heat curing, that is, the thickness from the surface 10a of the workpiece to the upper surface of the second coating film 40 after heat curing, is preferably 50 μm or more, more preferably 60 μm or more, preferably 80 μm or less, and more preferably 70 μm or less. If the thickness of the second coating film after heat curing is above the lower limit, the first coating film 30 is more easily protected, and the painted surface is easier to make smooth. If the thickness of the second coating film after heat curing is below the upper limit, the increase in product weight can be suppressed. The preferred lower and upper limits for the thickness of the second coating film after heat curing can be arbitrarily combined, for example, 50 to 80 μm is preferred. The thickness of the second coating film after heat curing is determined as the average value of measurements taken at any three locations.

[0041] In the method described above, by removing the masking material 20 while the first coating 30 is touch-dry, the edge of the first coating 30 on the border C side is less likely to peel up together with the masking material 20, thus suppressing peeling. As a result, the appearance of the border C becomes cleaner, and a painted product with excellent design can be consistently obtained. Furthermore, by making the thickness D1 of the first coating 30 in the touch-dry state less than the thickness D2 of the masking material 20, the edge of the first coating 30 on the border C side becomes even less likely to peel, and the appearance of the border C can be made even more consistently clean.

[0042] Furthermore, in the method according to this embodiment, the first coating 30 is not heat-cured before removing the masking material 20, and the first coating 30 and the second coating 40 are heat-cured simultaneously. This reduces the number of steps required, shortens the cycle time, reduces the amount of paint used to conserve resources, and contributes to reducing environmental impact by reducing energy consumption. In addition, since heat curing is not performed while the masking material 20 is present, the risk of defects such as blister formation can be avoided.

[0043] <Variation> The method for manufacturing the painted product according to the embodiment is not limited to the embodiments shown in Figures 1 to 4 above. For example, the method for manufacturing a painted object according to this embodiment may be applied to painting an object that has steps on its surface. When the boundary between the area to be painted with the first coating and the masked area not to be painted is set to follow the inner corner of a step, and the lower surface of the step is masked and the first coating is painted on the upper surface of the step, the edges of the first coating tend to peel off particularly easily when the masking material is removed. However, in this invention, peeling of the edges of the coating can be stably suppressed even in this case.

[0044] For example, as shown in Figure 5, in the case of a workpiece 10A having a step on its surface 10a, masking is performed by placing the masking material 20 in the masking area B below the step on the surface 10a of the workpiece 10A so that the trim C follows the inner corner of the step (step (i)). Next, as shown in Figure 6, the first paint is applied to the painted area A other than the masking area B on the surface 10a of the workpiece 10A, extending beyond the trim C between the painted area A and the masking area B to the masking area B, thereby forming the first paint film 30 (step (ii)).

[0045] Next, as shown in Figure 7, the masking material 20 is removed while the first coating 30 is touch-dry (step (iii)). Then, as shown in Figure 8, the second coating is applied to the surface 10a of the object to be coated from which the masking material 20 has been removed, so as to cover at least the trim C, to form the second coating 40 (step (iv)). Finally, the first coating 30 and the second coating 40 are heat-cured (baked) (step (v)).

[0046] Thus, even when painting a surface 10a of the object to be painted 10A that has steps, painting can be performed in the same way as the example object to be painted 10 shown in Figures 1 to 4 above, and the preferred embodiment is the same. In this case as well, by removing the masking material 20 when the first coating 30 is touch-dry, peeling of the edge of the first coating 30 on the border C side can be suppressed, and the appearance of the border C becomes cleaner. Furthermore, by making the thickness D1 of the first coating 30 in the touch-dry state less than the thickness D2 of the masking material 20, the appearance of the border C can be made more stable and cleaner. In addition, since the first coating 30 and the second coating 40 are heat-cured simultaneously, effects such as reduced man-hours, shortened cycle time, resource conservation, and reduced environmental impact can be obtained, as well as the effect of avoiding the risk of non-conformity such as blister formation.

[0047] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate.

[0048] <How to treat the paint edge> The method for treating the paint edge according to the embodiment is a method comprising the following (1) to (5). (1) Masking is performed by placing masking material on a part of the surface of the object to be painted. (2) A colored paint film is formed on the surface of the object to be painted, by applying colored paint to the painted area other than the masking area, extending beyond the boundary between the painted area and the masking area up to the masking area. (3) Remove the masking material when the colored coating is touch dry. (4) A clear coating is formed on the surface of the object to be painted from which the masking material has been removed by applying a transparent or translucent paint so as to cover at least the trimmed portion. (5) The colored coating and the clear coating are heated and cured.

[0049] In one example, as shown in Figure 1, masking is performed by placing masking material 20 in a masking area B on the surface 10a of the object to be painted 10A that is not to be painted with colored paint (step (1)). Next, as shown in Figure 2, colored paint is applied to the painted area A on the surface 10a of the object to be painted 10A, excluding the masking area B, and extending beyond the boundary C between painted area A and masking area B to the masking area B to form a colored paint film 30A (step (2)). Next, as shown in Figure 3, the masking material 20 is removed when the colored paint film 30A is touch dry (step (3)). Also, as shown in Figure 4, a clear or translucent paint is applied to the surface 10a of the object to be painted 10 from which the masking material 20 has been removed, so as to cover at least the boundary C, to form a clear paint film 40A (top clear) (step (4)). Finally, the colored paint film 30A and the clear paint film 40A are heat-cured (baked) (step (5)).

[0050] In another example, as shown in Figure 5, masking is performed by placing the masking material 20 in the masking area B below the step on the surface 10a of the object to be painted 10A, so that the trim C follows the inner corner of the step on the surface 10a of the object to be painted 10A (step (1)). Next, as shown in Figure 6, a colored paint is applied to the painted area A of the surface 10a of the object to be painted 10A, excluding the masking area B, extending beyond the trim C between the painted area A and the masking area B to the masking area B, thereby forming a colored paint film 30A (step (2)). Next, as shown in Figure 7, the masking material 20 is removed when the colored paint film 30A is touch-dry (step (3)). After that, as shown in Figure 8, a transparent or translucent paint is applied to the surface 10a of the object to be painted 10 from which the masking material 20 has been removed, so as to cover at least the trim C, thereby forming a clear paint film 40A (step (4)). Then, the colored coating 30A and the clear coating 40A are heat-cured (baked) (step (5)).

[0051] Thus, the method for treating the paint edge portion, including (1) to (5) above, can be carried out similarly in steps (i) to (v) of the manufacturing method of the painted product according to the above embodiment, using a colored paint as the first paint and a transparent or translucent paint as the second paint, and the preferred embodiment is the same.

[0052] By removing the masking material 20 while the colored coating 30A is touch-dry, peeling of the edge of the colored coating 30A on the trim C side can be suppressed, resulting in a cleaner appearance of the trim C. Furthermore, by making the thickness D1 of the touch-dry colored coating 30A less than the thickness D2 of the masking material 20, the appearance of the trim C can be made more stable and cleaner. In addition, since the colored coating 30A and the clear coating 40A are heat-cured simultaneously, effects such as reduced man-hours, shorter cycle times, resource conservation, and reduced environmental impact can be obtained, as well as the avoidance of non-conformity risks such as blister formation. [Examples]

[0053] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0054] [Example 1] A three-dimensional CFRP molded product was used as the object to be painted. The surface of this CFRP molded product was pre-treated with a primer coat and two coats of clear paint. Masking tape (50 μm thick) was applied to a portion of the surface of the molded product to mask it. Solid dark gray, a colored paint, was used as the first paint and sprayed onto the painted area of ​​the molded product's surface, excluding the masked area, extending beyond the dividing line to the masked area using a spray gun. After drying at room temperature (22.7°C) for 15 minutes, a first paint film (colored paint film) with a thickness of 19 μm was formed after it was touch-dry. After confirming that the painted surface of the first paint film did not stain the fingertip when lightly touched, the masking tape was removed. Next, clear paint was used as the second paint and sprayed onto the entire surface of the molded product using a spray gun, forming a second paint film (clear paint film) with a thickness of 60 μm when touch-dry. Subsequently, the first and second coatings were cured by heating at 80°C for 60 minutes. Figure 9 shows a photograph of the edge of the resulting painted object, taken from the second coating side. As shown in Figure 9, in Example 1, where the masking material was removed after the colored coating had dried to the touch, peeling of the edges of the colored coating on the trimming side was suppressed, resulting in a clean appearance at the trimming.

[0055] [Comparative Example 1] A three-dimensional CFRP molded product was used as the object to be painted. The surface of this CFRP molded product was prepped with a primer coat and two coats of clear paint. Masking tape (50 μm thick) was applied to a portion of the surface of the molded product to mask it. Using a colored paint, gray primer and solid red were spray-painted onto the painted area of ​​the molded product's surface, excluding the masked area, extending beyond the boundary line to the masked area. Furthermore, clear paint was spray-painted using a spray gun to form a 40 μm thick clear film on top of the colored paint film. After that, it was dried in an oven (80°C) for 40 minutes, and after heat curing, a 53 μm thick colored paint film was formed. After the colored paint film and clear paint film had cured, the masking tape was removed. After polishing the surface of the clear coating, the clear paint was spray-coated over the entire surface of the molded product using a spray gun to form a clear coating (top clear) with a thickness of 44 μm that was touch-dry, and then cured by heating at 80°C for 40 minutes. Figure 10 shows a photograph of the edge of the resulting coated product taken from the top clear side. As shown in Figure 10, in Comparative Example 1, where the masking material was removed after the colored coating and clear coating had hardened, the edges of the colored coating on the border side peeled off, exposing the underlying primer layer at the border, resulting in a poor appearance. [Explanation of Symbols]

[0056] 10,10A Object to be painted 10a surface 11 Base material 12. Primer layer 13 Clear coating 20 Masking materials 30 First coating 30A colored coating 40 Second coating 40A Clear Coating A Painting area B Masking area C Trim section

Claims

1. A method for manufacturing a painted object, comprising partially applying a first paint to the surface of an object to be painted, and then applying a second paint to obtain a painted object, Masking is performed by placing masking material on a part of the surface of the object to be painted, To form a first coating film by applying the first paint to the coating area on the surface of the object to be coated, excluding the masking area, extending beyond the boundary between the coating area and the masking area up to the masking area, The masking material is removed while the first coating film is touch-dry, On the surface of the object to be painted from which the masking material has been removed, a second paint is applied so as to cover at least the trimmed portion to form a second paint film. A method for manufacturing a painted product, comprising heating and curing the first coating film and the second coating film.

2. A method for manufacturing a coated product according to claim 1, comprising drying the first coating film to the touch at 50°C or below, and curing the first coating film and the second coating film at 60°C or above.

3. A method for manufacturing a painted article according to claim 1, wherein the first paint is a colored paint and the second paint is a transparent or translucent paint.

4. A method for manufacturing a painted product according to claim 1, wherein the thickness of the first coating film in a touch-dry state is less than the thickness of the masking material.

5. The method for manufacturing a coated product according to claim 1, wherein the thickness of the second coating film before heat curing is 1.5 to 3.0 times the thickness of the first coating film.

6. The method for manufacturing a coated product according to claim 1, wherein the thickness of the second coating film after heat curing is 50 to 80 μm.

7. The object to be painted has steps on the surface to be painted. A method for manufacturing a painted object according to claim 1, wherein masking is applied to the lower surface of the step on the surface of the object to be painted so that the trim portion follows the inner corner of the step, and the first paint is applied to the upper surface of the step.

8. The method for manufacturing a coated article according to claim 1, wherein the second coating film is only one layer.

9. The method for manufacturing a painted article according to claim 1, wherein the first paint is a two-component paint.

10. Masking is performed by placing masking material on a part of the surface of the object to be painted, To form a colored coating film on the surface of the object to be painted, by applying colored paint to the painted area other than the masking area, extending beyond the boundary between the painted area and the masking area up to the masking area, The masking material is removed when the colored coating is touch-dry, On the surface of the object to be painted from which the masking material has been removed, a clear or translucent paint is applied to cover at least the trimmed area to form a clear coating. A method for treating a painted edge, comprising heating and curing the colored coating and the clear coating.

Images