In-mold coating method

Abstract

To provide an in-mold coating method that can position a multi-layer coating film having a base coating film and a clear coating film on the surface of a thermosetting resin in a simple process.SOLUTION: The in-mold coating method includes: the material preparation step for preparing a thermosetting resin, base coating component particles containing a base coating component in microcapsule having a lower specific gravity than the thermosetting resin, clear coating component particles containing a clear coating component in microcapsule having a lower specific gravity than the thermosetting resin and having a lower specific gravity than the base coating component particles; the dispersing step for dispersing the base coating component particles and the clear coating component particles in the molten thermosetting resin; the feeding step for feeding the molten thermosetting resin in which the base coating component particles and the clear coating component particles are dispersed into the mold; the heating and molding step for heating a molten thermosetting resin, in which the base coating component particles and the clear coating component particles dispersed therein are charged into a mold, to a semi-curing temperature for molding; and the coating film forming step of heating the thermosetting resin, which contains base coating component particles and clear coating component particles formed in the heating and molding step, to a curing temperature to form a coating film containing base coating components and clear coating components on the surface of the thermosetting resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an in-mold coating method.

Background Art

[0002] Patent Document 1 includes a gun body facing a cavity formed by a mold, a paint shaft slidably provided inside the gun body, and a gas shaft slidably provided inside the paint shaft. In the gun body, a paint supply passage and a paint discharge passage through which paint flows are formed, and in the gun body and the paint shaft, a gas flow passage through which gas flows is formed. On the outer peripheral surface of the paint shaft, a recess is formed from the penetration position of the paint supply passage to the penetration position of the paint discharge passage in a state where the tip of the paint shaft has advanced to the tip of the gun body. On the tip side of the paint shaft, an injection gun having a gas flow hole that can be opened and closed by the tip of the gas shaft is used to form a coating film on the surface of a molded product. The in-mold coating method includes a supply step of supplying molten thermoplastic resin into the cavity, a gas discharge step of discharging gas into the cavity using the injection gun before the resin supplied in the supply step is completely solidified to form a gap between the mold surface of the mold and the surface of the resin, a gas degassing step of degassing the gas in the gap between the mold surface of the mold and the surface of the resin using the injection gun, and a paint discharge step of discharging paint into the gap formed in the gas discharge step using the injection gun to form a coating film on the surface of the resin.

[0003] Patent Document 2 describes a method for manufacturing a functional sheet having a step (A) of forming a pattern layer on a base material A and / or a base material B, a step (B) of coating a curable resin composition containing a functional material and a curable resin on the side of the pattern layer provided on the base material A and / or the base material B in step (A) and / or on the base material A or the base material B on which the pattern layer is not provided to form a functional layer, and a step (C) of laminating the base material A and the base material B via an adhesive so that the pattern layer and the functional layer are between the base material A and the base material B. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-17906 [Patent Document 1] Japanese Patent Publication No. 2010-82819 [Overview of the project] [Problems that the invention aims to solve]

[0005] Thermosetting resins have poor weather resistance. Therefore, techniques for applying a coating or film to the surface of thermosetting resins to create a protective layer are known. However, when a protective layer is laminated to the surface of a thermosetting resin using an adhesive, delamination and / or expansion of the adhesive interface may occur. Furthermore, contamination of the adhesive interface between the molding of the thermosetting resin and the adhesion of the protective layer may occur, potentially leading to poor adhesion.

[0006] In response to these challenges, the in-mold coating method described in Patent Document 1 has attracted attention. In the in-mold coating method, paint is injected into the gap between the surface of the semi-cured thermosetting resin and one side of the mold during the molding process of the thermosetting resin, thereby forming a coating film on the surface of the thermosetting resin. However, in the case of the conventional in-mold coating method, complex process control is required, such as controlling the gap for injecting paint into the surface of the semi-cured thermosetting resin and controlling the timing of paint injection, which can lead to increased manufacturing costs and / or decreased productivity. Furthermore, in the case of the conventional in-mold coating method, there is a problem in that it is difficult to form a multi-layer coating film in which a clear coating film is placed on top of the base coating film.

[0007] Therefore, the present invention aims to provide an in-mold coating method that enables the placement of a multilayer coating having a base coating and a clear coating on the surface of a thermosetting resin in a simple process. [Means for solving the problem]

[0008] The inventors of the present invention have investigated various means to solve the above-mentioned problems. The inventors of the present invention have prepared a thermosetting resin, base coating component particles containing base coating components in microcapsules with a specific gravity lower than that of the thermosetting resin, and clear coating component particles containing clear coating components in microcapsules with a specific gravity lower than that of the thermosetting resin and with a specific gravity lower than that of the base coating component particles. By dispersing the base coating component particles and clear coating component particles in molten thermosetting resin, and then heating and molding at a semi-curing temperature followed by heating and molding at a curing temperature, a thermosetting resin layer, a base coating component particle layer, and a clear coating component particle layer are formed based on the difference in specific gravity, and as a result, a coating film containing base coating components and clear coating components is formed on the surface of the thermosetting resin. Based on the above findings, the inventors of the present invention have completed the present invention.

[0009] In other words, the present invention encompasses the following aspects and embodiments. (Embodiment 1) A material preparation step comprising: preparing a thermosetting resin; base coating component particles in which base coating components are encapsulated in microcapsules having a lower specific gravity than the thermosetting resin; and clear coating component particles in which clear coating components are encapsulated in microcapsules having a lower specific gravity than the thermosetting resin and having a lower specific gravity than the base coating component particles. Dispersion step: Dispersing base paint component particles and clear paint component particles in molten thermosetting resin. A filling step involves pouring a molten thermosetting resin, in which base paint component particles and clear paint component particles are dispersed, into a mold. A heat molding process involves heating a molten thermosetting resin containing dispersed base paint component particles and clear paint component particles, which has been placed in a mold, to a semi-curing temperature to form the resin. A coating film forming step involves heating a thermosetting resin containing base paint component particles and clear paint component particles, which has been molded in a heat molding step, to a curing temperature to form a coating film containing base paint components and clear paint components on the surface of the thermosetting resin. An in-mold coating method, including [a specific method]. [Effects of the Invention]

[0010] The present invention provides an in-mold coating method that allows for the placement of a multilayer coating having a base coating and a clear coating on the surface of a thermosetting resin in a simple process. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below.

[0012] One aspect of the present invention relates to an in-mold coating method.

[0013] The method according to this embodiment includes a material preparation step, a dispersion step, a feeding step, a heat molding step, and a coating film formation step. Each step will be described in detail below.

[0014] [1. Material preparation process] This process includes preparing a thermosetting resin, base coating component particles, and clear coating component particles.

[0015] The thermosetting resin, base coating component, and clear coating component can be appropriately selected from resins and coating components commonly used in the relevant art.

[0016] The base paint component particles prepared in this process encapsulate the base paint component in microcapsules with a specific gravity lower than that of the thermosetting resin. In addition to the base paint component, the base paint component particles also encapsulate a gas such as air, nitrogen, helium, or argon within the microcapsules. By encapsulating a predetermined concentration of gas, the base paint component particles can have a specific gravity lower than that of the thermosetting resin.

[0017] The clear coating component particles prepared in this process contain the clear coating component in microcapsules with a specific gravity lower than that of the thermosetting resin, and also have a specific gravity lower than that of the base coating component particles. In addition to the clear coating component, the clear coating component particles contain a gas such as air, nitrogen, helium, or argon within the microcapsules. By containing a predetermined concentration of gas, the specific gravity of the clear coating component particles can be made lower than that of the base coating component particles.

[0018] The microcapsules constituting the base coating particle and the clear coating particle preferably contain a thermoplastic resin as the main component. Thermosetting resins commonly used in this art typically have a specific gravity in the range of 1.6 to 2.3. Base coating components commonly used in this art typically have a specific gravity in the range of 0.8 to 1.3, including the solvent. Clear coating components commonly used in this art typically have a specific gravity in the range of 1.2 to 1.3, including the solvent. The gas exemplified above typically has a specific gravity of about 0.001. In contrast, the main component of the microcapsule exemplified above typically has a specific gravity in the range of 0.9 to 1.2. Therefore, both the base coating particle and the clear coating particle have a specific gravity lower than that of the thermosetting resin. Furthermore, by encapsulating a predetermined concentration of gas within the microcapsules of the base coating particle and the clear coating particle, the clear coating particle can have a specific gravity lower than that of the base coating particle.

[0019] The thermosetting resin, the base paint component particles, and the clear paint component particles may be prepared by purchasing those having the characteristics described above. Alternatively, the thermosetting resin, the base paint component particles, and the clear paint component particles may be prepared by producing them by oneself. The base paint component particles and the clear paint component particles can be produced, for example, by adding a base paint component or a clear paint component and the gas exemplified above to a gel composed of the components exemplified above, dispersing them, and forming microcapsules encapsulating the base paint component or the clear paint component and the gas. As a method for producing the base paint component particles and the clear paint component particles, for example, the method described in Fumio Takemura, AIST TODAY, 2007, Vol. 1, p. 28-29 can be referred to.

[0020] [2. Dispersion Step] This step includes dispersing the base paint component particles and the clear paint component particles in the molten thermosetting resin.

[0021] In this step, it is preferable to put the base paint component particles and the clear paint component particles into the molten thermosetting resin and knead these materials. Kneading of the materials can be carried out using a kneading device such as a mixer or a kneader commonly used in the art.

[0022] [3. Injection Step] This step includes injecting the molten thermosetting resin in which the base paint component particles and the clear paint component particles are dispersed into a mold.

[0023] In this step, it is preferable to use an injection device commonly used in the art to inject the molten thermosetting resin in which the base paint component particles and the clear paint component particles are dispersed into a mold.

[0024] [4. Heat Molding Step] This step includes heating and molding the molten thermosetting resin in which the base paint component particles and the clear paint component particles are dispersed and injected into a mold to a semi-curing temperature.

[0025] In this process, when the molten thermosetting resin containing dispersed base paint component particles and clear paint component particles, which has been placed in the mold, is heated to a semi-curing temperature, the molten thermosetting resin begins to harden. At this time, a thermosetting resin layer, a base paint component particle layer positioned above the thermosetting resin layer, and a clear paint component particle layer positioned above the base paint component particle layer are formed based on the difference in specific gravity.

[0026] In this process, the semi-curing temperature can be appropriately set based on the type of thermosetting resin used. For example, the semi-curing temperature is preferably 5°C or less, and more preferably 10°C or less, than the curing temperature of the thermosetting resin used. If this process is carried out at a temperature exceeding the above upper limit, the layer arrangement based on the difference in specific gravity may not proceed sufficiently, and it may not be possible to form a coating film containing base paint components and a coating film containing clear paint components in the desired arrangement. Therefore, by carrying out this process under the above conditions, a thermosetting resin having a coating film containing base paint components and a coating film containing clear paint components in the desired arrangement can be obtained.

[0027] [5. Paint film formation process] This process includes heating a thermosetting resin containing base paint component particles and clear paint component particles, which has been molded in a heat molding process, to a curing temperature to form a coating film containing the base paint component and clear paint component on the surface of the thermosetting resin.

[0028] As described above, the thermosetting resin containing base paint component particles and clear paint component particles, which is molded in the heat molding process, has a thermosetting resin layer, a base paint component particle layer positioned above the thermosetting resin layer, and a clear paint component particle layer positioned above the base paint component particle layer, based on the difference in specific gravity. In this process, when the thermosetting resin having the layer structure is heated to the curing temperature, the resin in the thermosetting resin layer hardens, and the microcapsules contained in the base paint component particle layer and the clear paint component particle layer melt, forming a coating film containing the base paint component and a coating film containing the clear paint component. As a result, the interface between the thermosetting resin and the coating film containing the base paint component, and the interface between the coating film containing the base paint component and the coating film containing the clear paint component become mixed phases, improving adhesion.

[0029] In this process, the curing temperature should be set appropriately based on the type of thermosetting resin used.

[0030] As described in detail above, by implementing the method of this embodiment, a thermosetting resin having a coating film containing a base coating component and a multi-layer coating film containing a clear coating component laminated on its surface can be manufactured in a simple process. Therefore, by implementing the method of this embodiment, a thermosetting resin having a coating film containing a base coating component and a multi-layer coating film containing a clear coating component laminated on its surface can be manufactured at a low manufacturing cost and / or with high productivity.

Claims

[Claim 1] A material preparation step comprising: preparing a thermosetting resin; base coating component particles in which base coating components are encapsulated in microcapsules having a lower specific gravity than the thermosetting resin; and clear coating component particles in which clear coating components are encapsulated in microcapsules having a lower specific gravity than the thermosetting resin and having a lower specific gravity than the base coating component particles. Dispersion step: Dispersing base paint component particles and clear paint component particles in molten thermosetting resin. A filling step involves pouring a molten thermosetting resin, in which base paint component particles and clear paint component particles are dispersed, into a mold. A heat molding process involves heating a molten thermosetting resin containing dispersed base paint component particles and clear paint component particles, which has been placed in a mold, to a semi-curing temperature to form the resin. A coating film forming step involves heating a thermosetting resin containing base paint component particles and clear paint component particles, which has been molded in a heat molding step, to a curing temperature to form a coating film containing base paint components and clear paint components on the surface of the thermosetting resin. An in-mold coating method, including [a specific method].