JP2018204091A - Method for forming film on resin molding - Google Patents

Abstract

To provide a method for forming a film excellent in adhesion, capable of easily removing abrasive grains without taking labor when the surface is roughened by the abrasive grains and easily performing hydrophilic treatment for improving the hydrophilicity of the resin molding surface after the surface is roughened by the abrasive grains.SOLUTION: The method for forming a film, capable of forming a metal film on a resin molding comprises: roughening the surface of the resin molding using sodium-bicarbonate powder as abrasive grains used to roughen the surface; and forming the film on the surface of the hydrophilized resin-molding.SELECTED DRAWING: None

Description

  The present invention relates to a film forming method for forming a metal film on the surface of a resin molded product. More specifically, the present invention relates to a film forming method for a resin molded product capable of forming a metal film having excellent adhesion even on a resin molded product formed by a 3D printer.

For the purpose of imparting various functions such as weather resistance, surface conductivity, electromagnetic wave shielding properties, and antibacterial properties to a resin molded product, a metal film is conventionally formed on the surface thereof. As the method, for example, a vacuum plating method such as vacuum deposition or sputtering, an electroless plating method, an electroless / electroplating method in which electroplating is performed after the electroless plating is known. Since the resin molded product is non-conductive and cannot be directly electroplated, these methods have been put to practical use in various fields.
And when forming a metal film on the surface of a resin molded product, for example, as disclosed in Patent Document 1 below, the surface of the resin molded product is roughened with abrasive grains in order to increase the adhesion of the film to the resin molded product. The metal coating is formed after the surface.

JP 2000-124583 A

However, in the case where the abrasive grains are non-conductive inorganic substances such as silicon carbide and alumina, the abrasive grains sink into the surface of the resin molded product, thereby adversely affecting the formation of the metal film. Therefore, it is necessary to remove those abrasive grains, but it is very difficult to remove the abrasive grains that have entered the surface.
Further, there has been a demand for a proposal of an abrasive treatment that facilitates a hydrophilic treatment for improving the hydrophilicity of the surface of the resin molded product performed after the roughening treatment using abrasive grains.
Therefore, the film forming method of the present invention can be easily removed without troublesome removal of the abrasive grains in the abrasive treatment, and the hydrophilicity of the surface of the resin molded product performed after the roughening treatment using the abrasive grains. It is an object of the present invention to provide a method for forming a film that is easy to perform a hydrophilic treatment for improving the property and has excellent adhesion.

As a result of earnest research to meet such demands, the present invention can use a baking soda powder as an abrasive grain used for the roughening treatment of a resin molded product, so that abrasive grains made of the baking soda powder can be easily removed after the roughening treatment. It was also found that the surface of the resin molded product can be easily hydrophilized due to the chemical properties of the baking soda powder.
The film forming method of the present invention is based on the above knowledge, and as described in claim 1, is a film forming method for forming a metal film on a resin molded product, wherein the resin molded product is roughened. A coating film is formed on the surface of the resin molded article that has been roughened by using baking soda powder as an abrasive used in the treatment and has been made hydrophilic.
A film forming method according to claim 2 is characterized in that, in the film forming method according to claim 1, baking soda powder is sprayed on the surface of the resin molded product.
The film forming method according to claim 3 is characterized in that, in the film forming method according to claim 2, the baking powder is sprayed in a wet manner.
The film forming method according to claim 4 is characterized in that, in the film forming method according to claim 2, spraying of the baking soda powder is performed in a dry manner.
The film forming method according to claim 5 is the film forming method according to any one of claims 1 to 4, wherein the average particle diameter of the baking soda powder is 60 to 300 µm.
The film forming method according to claim 6 is characterized in that, in the film forming method according to any one of claims 2 to 5, the spray pressure of the baking soda powder is 0.15 to 0.65 MPa. To do.
The film forming method according to claim 7 is the film forming method according to any one of claims 1 to 6, wherein the surface of the resin molded product is roughened to a Ra value of 0.5 to 3.0 μm. It is characterized by doing.
The film forming method according to claim 8 is the film method according to any one of claims 1 to 7, wherein the resin molded product is formed by a 3D printer.

  In the film forming method of the present invention, the surface of the resin molded product is roughened using baking soda powder, and a metal film is formed on the hydrophilic surface of the resin molded product. Unlike conventional abrasive grains made of metal or ceramic, baking soda powder can be easily removed after surface roughening of resin molded products, so it does not sink and is easy due to the chemical properties of baking soda powder. Since the surface of the resin molded product can be made hydrophilic and the subsequent plating process does not take much time, a metal coating with excellent adhesion on the surface of various resin molded products, including resin molded products by 3D printers, is not impaired. There is an effect that it can be easily formed. Moreover, when the metal coating is formed into a thick film due to excellent adhesion, an excellent effect is obtained that excellent mechanical properties can be imparted to various resin molded products including resin molded products by 3D printers.

Embodiments of the film forming method of the present invention will be described below, but the film forming method of the present invention is not limited to the following embodiments.
In the film forming method of the present invention, the surface of the resin molded article is roughened using baking soda powder, and a metal film is formed on the hydrophilic surface of the resin molded article.

  The surface roughening treatment using abrasive grains made of baking soda powder is not particularly limited, and examples thereof include a surface roughening method such as blasting for spraying abrasive grains and barrel treatment for rubbing with abrasive grains. However, it is preferable to carry out by blasting such as wet blasting or dry blasting. In particular, in the case of wet blasting, the baking soda powder dissolves in water simultaneously with the blasting treatment to make the surface of the resin molded product hydrophilic, so there is no need for a separate hydrophilization treatment and the subsequent formation of the metal film is not troublesome. Therefore, it is preferable. Also, in the case of dry blasting, the surface of the resin molded product can be easily made hydrophilic by washing with water after the blasting treatment as in the case of wet blasting. Therefore, the blasting treatment is suitable for the film forming method of the present invention.

  The average particle size of the baking soda powder is preferably 60 to 300 μm, particularly preferably 100 to 200 μm. This is because if the thickness is less than 60 μm, roughening is not sufficient and good adhesion of the metal film cannot be obtained, and if it exceeds 300 μm, the surface is too rough and adhesion to the metal film is deteriorated.

  Moreover, when spraying the said sodium bicarbonate powder on the surface of a resin molded product, the spraying pressure of the said sodium bicarbonate powder is preferably 0.15 to 0.65 MPa, particularly preferably 0.2 to 0.5 MPa. If it is less than 0.15 MPa, roughening is not sufficient, and good adhesion of the metal film cannot be obtained, and if it exceeds 0.65 MPa, it is too rough and adhesion to the metal film is deteriorated. It is.

  Further, in roughening using baking soda powder, it is preferable to roughen the surface of the resin molded product to 0.5 to 3.0 μm in terms of Ra value, and in particular to 1.0 to 2.7 μm in terms of Ra value. It is preferable to roughen the surface. This is because when the Ra value is less than 0.5 μm, roughening is not sufficient, and good adhesion of the metal film cannot be obtained, and when the Ra value exceeds 3.0 μm, the metal film is too rough. This is because the adhesion of the resin becomes worse.

The molding method of the resin molded product is not particularly limited, and includes injection molding, compression molding, blow molding, insert molding, FDM method (hot melt lamination method), SLS method (powder sintering additive manufacturing method), It is widely applicable to resin molded products by 3D printers such as SLA method (stereolithography method), but in the case of 3D printers using FDM method (hot melt lamination method) or SLS method (powder sintering lamination molding method), resin lamination Large irregularities are formed on the surface due to the stacking marks at the time, and two irregularities are formed by forming fine irregularities by roughening by blasting treatment, and a strong anchor effect at the time of metal film formation Has occurred. In addition, since the main resin used in the FDM method (hot melt lamination method) and the SLS method (sintered powder sintering method) has a hydrophilic chemical bond, the physical bond and the chemical Good adhesion to the metal coating can be obtained due to the synergistic effect of simple bonding.
Therefore, the method for forming a film of a resin molded product of the present invention is suitable for forming a metal film on a resin molded product by a 3D printer.

  The resin constituting the resin molded product is not particularly limited, but is not limited to polyamide resin such as nylon, polyester resin such as polylactic acid, epoxy resin, polyurethane resin, polyvinyl chloride resin, acrylic resin, polycarbonate resin, polystyrene resin. And ABS resin (acrylonitrile-butadiene-styrene copolymer resin).

  The hydrophilicity of the surface of the resin molded product is easily obtained from the chemical properties of the baking soda powder, and as described above, in the case of wet blasting, it is obtained simultaneously with the spraying of the baking soda powder on the surface of the resin molded product. In this case, it can be easily obtained by washing with water following the spraying of the baking soda powder onto the surface of the resin molded product. Hydrophilization due to the chemical properties of baking soda powder is not limited to the above blasting treatment, and the resin molded product can be easily hydrophilized also by immersion treatment using alkaline solution or barrel treatment using baking soda powder. Can do.

  Formation of the metal film on the surface of the roughened resin molded product is not particularly limited to formation of the metal film by plating. From the viewpoint of utilizing hydrophilization with sodium bicarbonate powder, the surface is then adjusted with a conditioner solution to give a catalyst such as palladium chloride and stannous chloride, and electroless nickel is formed to form a metal film. Electrolytic copper plating or electrolytic nickel plating may be performed.

Next, specific examples of the coating film forming method of the present invention will be described.
Example 1
First, a polylactic acid (PLA) resin molded product, which is a polyester-based thermoplastic resin having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, was prepared using a 3D printer (manufactured by Maker Bot Replicator 2) of the FDM method (heat melting lamination method).
Next, baking soda powder having an average particle size of 100 μm was sprayed onto the surface of the resin molded product at a pressure of 0.2 MPa using a blast machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Next, the surface was adjusted by dipping in a conditioner solution (Condizer SP manufactured by Okuno Pharmaceutical Co., Ltd.).
Subsequently, it was immersed in a mixed solution of palladium chloride, stannous chloride and concentrated hydrochloric acid (Catalyst C-7 manufactured by Okuno Pharmaceutical Co., Ltd.) to give a catalyst.
Next, activation was performed by dipping in a diluted hydrochloric acid solution.
Next, an electroless nickel plating film having a thickness of 1 μm was formed by plating with an alkaline electroless nickel plating solution (chemical nickel EXC manufactured by Okuno Pharmaceutical Co., Ltd.).
Next, electrolytic copper plating was performed with a solution of copper sulfate (ELECAPPER 25, manufactured by Okuno Pharmaceutical Co., Ltd.) to form a 37 μm thick copper plating film.
Finally, electrolytic nickel plating was performed in a solution mainly composed of nickel sulfate and nickel chloride to form a nickel plating film having a thickness of 15 μm.
The electroless nickel plating conditions were controlled at pH 8.5 to 9.5, solution temperature 25 to 35 ° C., and plating time 10 to 12 minutes. The conditions for electrolytic copper plating were a current density of 2 A / dm ² , a temperature of room temperature, and a plating time of 80 to 90 minutes. The conditions for electrolytic nickel plating were a current density of 2 A / dm ² , a temperature of 45 to 55 ° C., and a plating time of 20 to 30 minutes.

Example 2
Polylactic acid (PLA) resin molding, which is a polyester-based thermoplastic resin of 50 mm x 50 mm x 3 mm thickness, using a 3D printer (Qholia, manufactured by Kyuho Metals Co., Ltd.) with a high modeling accuracy FDM method (heat melting lamination method) An article was made.
Next, baking soda powder having an average particle size of 100 μm was sprayed at a pressure of 0.5 MPa using a blasting machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Example 3
Using a SLS method (powder sintering additive manufacturing method) 3D printer (RaFaEL manufactured by Aspect Co., Ltd.), a nylon 12 resin (ASPEX-PA) molded product, which is a polyamide resin having a length of 32 mm, a width of 35 mm and a thickness of 3 mm did.
Subsequently, baking soda powder having an average particle diameter of 100 μm was sprayed at a pressure of 0.2 MPa using a blasting machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Example 4
A nylon 12-based resin (PA2200) molded product, which is a polyamide-based resin having the same shape as that of Example 2, was prepared using a 3D printer (former P of EOS manufactured by SOS method).
Subsequently, baking soda powder having an average particle diameter of 100 μm was sprayed at a pressure of 0.2 MPa using a blasting machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Example 5
Using an SLA method (stereolithography method) 3D printer (ACCULAS (registered trademark) series manufactured by DEMEC Co., Ltd.), a molded product of epoxy resin (SCR (registered trademark) 737) having a length of 45 mm, a width of 20 mm, and a thickness of 4 mm is produced. did.
Next, baking soda powder having an average particle size of 100 μm was sprayed at a pressure of 0.5 MPa using a blasting machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Comparative Example 1
A molded product having a length of 50 mm, a width of 50 mm, and a thickness of 3 mm was produced in the same manner as in Example 1.
Next, alumina powder having an average particle size of about 100 μm was sprayed at a pressure of 0.2 MPa using a blast machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Comparative Example 2
In the same manner as in Example 2, a molded product having a length of 50 mm, a width of 50 mm, and a thickness of 3 mm was produced.
Next, alumina powder having an average particle size of about 100 μm was sprayed at a pressure of 0.5 MPa using a blast machine (SGK-3LD manufactured by Fuji Seisakusho Co., Ltd.).
Thereafter, the same treatment as in Example 1 was performed to form an electroless nickel plating film (1 μm), a copper plating film (37 μm), and a nickel plating film (15 μm) in this order on the surface of the resin molded product.

Next, evaluations of the appearance and adhesion of the metal coatings of the resin molded products of Examples 1 to 5 and Comparative Examples 1 and 2 are shown. The evaluation method was performed as follows.
The appearance and adhesion were evaluated at the stage where an electroless nickel plating film having a thickness of 1 μm was formed on each resin molded product.
(1) Appearance:
The appearance of the electroless nickel plating film was visually evaluated. At that time, the presence or absence of abnormalities such as no plating, pinholes, pits and blisters was confirmed.
(2) Adhesion test:
According to JIS H 8504, the surface of the electroless nickel plating film is cut with a cutter to reach the substrate, and after the adhesive tape is applied, the plating film is peeled off when the tape is pulled perpendicular to the plating surface. The presence or absence was examined.
The results obtained by the evaluation method are shown in Table 1 below.

  As shown in Table 1 above, an electroless nickel plating film excellent in adhesion with good appearance was formed on the entire surface of the sample surfaces of Examples 1 to 5 obtained by the film forming method of the present invention. On the other hand, in Comparative Example 1, almost the whole was unplated, and in Comparative Example 2, most of the end portions were unplated.

Next, bending strength and bending elastic modulus were tested as mechanical properties before and after plating of the resin molded product of Example 1 obtained by a 3D printer. In addition, bending strength and bending elastic modulus were performed as follows.
Using a universal material testing machine (AG-250kNI, manufactured by Shimadzu Corporation), bending strength and flexural modulus were determined according to JIS K7171. Specifically, a concentrated load is applied to the center of the resin molded product, and the resin molded product is deflected at a constant speed until it breaks or reaches the specified deflection, and the load applied to the resin molded product during that time is measured. Bending strength and flexural modulus were further calculated.
The values of bending strength and bending elastic modulus obtained by the above test are shown in Table 2 below.

  As shown in Table 2 above, the bending strength and the flexural modulus of the resin molded product formed with the metal film of Example 1 obtained by the coating film forming method of the present invention are compared with those of the resin molded product with no film formed. Thus, a value of 1.7 times in bending strength and 5.2 times in flexural modulus was obtained, and mechanical properties superior to those of a resin molded product having no film formed were provided.

  In the film forming method of the present invention, a baking soda powder, which is an environmentally friendly chemical substance, is used for abrasive grains, and a metal film having excellent adhesion on the surface of various resin molded products including resin molded products by 3D printers. This is industrially useful because it can be easily formed without impairing the thickness.

Claims (8)

A film forming method for forming a metal film on a resin molded product, wherein the resin molded product is roughened by using baking soda powder as abrasive grains used in the surface roughening treatment of the resin molded product, and is made hydrophilic. A method of forming a film, comprising forming a film on a surface. The film forming method according to claim 1, wherein baking soda powder is sprayed on a surface of the resin molded product. The film forming method according to claim 2, wherein the baking powder is sprayed in a wet process. The film forming method according to claim 2, wherein the baking powder is sprayed by a dry method. The film forming method according to any one of claims 1 to 4, wherein an average particle diameter of the baking soda powder is 60 to 300 µm. The film forming method according to any one of claims 2 to 5, wherein a spray pressure of the baking soda powder is 0.15 to 0.65 MPa. The film forming method according to claim 1, wherein the surface of the resin molded product is roughened to a Ra value of 0.5 to 3.0 μm. The film forming method according to any one of claims 1 to 7, wherein the resin molded product is molded by a 3D printer.