JP6888869B2 - Paint composition - Google Patents

Description

The present invention relates to a coating composition, and relates to a coating composition that can be used for a mold release treatment for a mold mainly used in a molding process.

Conventionally, a method of forming a coating film on the surface of an object by using a coating composition containing a solid lubricant in order to obtain lubricity has been known. In that case, as a typical solid lubricant, a fluorine-based resin such as polytetrafluoroethylene is widely used from the viewpoint of being able to form a coating film having a low friction coefficient and lubricity.

For example, Patent Document 1 discloses a coating composition containing a fluororesin as a solid lubricant. A coating composition containing a fluororesin as a solid lubricant is a coating composition capable of forming a coating film having lubricity.

Japanese Unexamined Patent Publication No. 2016-193968 Japanese Unexamined Patent Publication No. 2007-217448

By the way, the surface of the mold may be coated with a low-friction coating film by the coating composition, and the molded product may be molded by the mold coated with the coating film. By coating the surface of the mold with a coating film having lubricity, it is possible to improve the mold releasability of the molded product with respect to the mold.

However, the above-mentioned fluorine-based resin such as polytetrafluoroethylene and polyamide-imide resin are insulating materials. That is, the coating film formed by these compositions has a surface resistivity of more than 1 × 10 ¹³ Ω / □, which is extremely high. Therefore, the coating film formed by these compositions is liable to be charged with static electricity. When the electrostatic coating film and the molded product come into contact with each other, the molded product is charged with static electricity, which may reduce the mold releasability of the molded product.

In order to improve the conductivity of the coating film, for example, it is conceivable that the coating composition contains carbon black having conductivity. However, the coating film containing carbon black has a reduced lubricity on the surface of the coating film.

On the other hand, when a coating film is coated on the surface of a mold with a coating composition and a molded product is molded by a mold coated with the coating film, the coating film is also required to have abrasion resistance.

In order to improve the wear resistance of the coating film, for example, it is conceivable to include a hard filler in the coating composition. However, the peritoneum containing the hard filler has improved wear resistance, but the lubricity of the coating film surface is reduced.

As described above, since lubricity, abrasion resistance, and conductivity are in a trade-off relationship in the coating film, a coating film capable of simultaneously satisfying lubricity, abrasion resistance, and conductivity can be obtained. Development of a coating composition that can be formed is required.

Patent Document 2 discloses a molding resin composition containing a predetermined amount of a modified polyamide-imide resin obtained by modifying an aromatic polyamide-imide resin, which is excellent in the aromatic polyamide-imide resin. A composition that imparts mold releasability without impairing various properties such as abrasion resistance is shown. However, this composition is a resin composition for molding a molded product, and does not form a coating film that covers the surface of a mold used for molding, for example.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a coating composition capable of forming a coating film that simultaneously satisfies lubricity, abrasion resistance, and conductivity. And.

As a result of diligent research to achieve the above problems, the present inventors have found that the above problems can be solved if the coating composition contains carbon black and an inorganic filler in a predetermined ratio, and the present invention has been made. Has been completed. Specifically, the present invention provides the following.

(1) The first invention of the present invention contains a polyamide-imide resin, a solid lubricant, carbon black, an inorganic filler, and a solvent, and the content of the inorganic filler is 100 volumes of the solid lubricant. A coating composition having 5 parts by volume or more and 25 parts by volume or less with respect to parts, and the content of the carbon black is 1.7 parts by volume or more and 5.3 parts by volume or less with respect to 100 parts by mass of the polyamide-imide resin. ..

(2) The second invention of the present invention is a coating composition in which the inorganic filler is a plate-shaped iron oxide in the first invention.

(3) The third invention of the present invention is the coating composition used for the mold release treatment for the mold used for the molding process in the first or second invention.

(4) In the fourth invention of the present invention, in any one of the first to third inventions, the content of the solid lubricant is 20 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the polyamide-imide resin. A coating composition.

(5) A fifth invention of the present invention is a coating composition in which the solid lubricant is a fluororesin lubricant in any one of the first to fourth inventions.

According to the coating composition of the present invention, it is possible to form a coating film that simultaneously satisfies lubricity, abrasion resistance, and conductivity.

It is a graph which shows the change of the friction coefficient with respect to the measurement time in the measurement of the friction coefficient of the coating film formed by the coating composition of Example 1, Comparative Example 1, and Comparative Example 34.

Hereinafter, the coating composition of one embodiment of the present invention (hereinafter, referred to as the coating composition of the present invention) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

≪Paint composition≫
The coating composition of the present invention is a coating composition containing a polyamide-imide resin, a solid lubricant, carbon black, an inorganic filler, and a solvent. The content of the inorganic filler is 5 parts by volume or more and 25 parts by volume or less with respect to 100 parts by volume of the solid lubricant. Further, the content of carbon black is 1.7 parts by mass or more and 5.3 parts by mass or less with respect to 100 parts by mass of the polyamide-imide resin.

As described above, the coating composition of the present invention is a coating composition containing a solid lubricant. Therefore, lubricity can be imparted to the object by applying it to various metal products or objects such as metal molds.

Further, the coating composition of the present invention contains carbon black and an inorganic filler in a predetermined ratio. According to this coating composition, lubricity, abrasion resistance, and conductivity can be effectively imparted to the formed coating film. As described above, the coating composition of the present invention has a technical feature in that lubricity, abrasion resistance, and conductivity can be imparted to the coating film. Since this coating film has high lubricity and high conductivity, the mold releasability of the molded product to the mold is extremely high. Therefore, from the viewpoint of high mold releasability of the molded product to the mold, it can be particularly preferably used for the mold releasable treatment of the mold used in the molding process.

Hereinafter, the polyamide-imide resin, solid lubricant, carbon black, inorganic filler, and solvent contained in the coating composition of the present invention will be described.

[Polyamide-imide resin]
The coating composition of the present invention contains a polyamide-imide resin. Thereby, adhesion, lubricity, and heat resistance can be imparted to the coating film.

The polyamide-imide resin is not particularly limited, and a polyamide-imide resin that is soluble in a solvent in the coating composition can be used.

For example, commercially available polyamide-imide resins include Vilomax HR11NN, Vilomax 13NX, Vilomax 26NX (all manufactured by Toyobo Co., Ltd.), HI-405, HI-406, HPC-5020, HPC-6000, HPC- 7200, HPC-9000 (all manufactured by Hitachi Kasei Kogyo Co., Ltd.) and the like can be mentioned.

By containing the polyamide-imide resin in the coating composition, it is possible to impart adhesion, lubricity, and heat resistance to the coating film.

[Solid lubricant]
The solid lubricant is not particularly limited as long as it can be uniformly dispersed in the coating composition and can impart lubricity to the coating film, but among them, a fluororesin lubricant may be used. preferable.

Specifically, examples of the fluororesin lubricant include polytetrafluoroethylene (PTFE), fluorated ethylene polyethylene (FEP), perfluoroalkyl (PFA), ethylene tetrafluoroethylene (ETFE), and polychlorotrifluoroethylene. (PCTFE), polyvinyl fluoride (PVF), perfluoroalkoxy alkane resin (PFA), ethylene / ethylene tetrafluoride copolymer (ETFE) and the like, and these may be used alone or in combination of two or more. be able to. Among them, it is particularly preferable to use polytetrafluoroethylene (PTFE).

Fluororesin lubricants have stable viscoelasticity and have soft properties among solid lubricants. Further, the fluororesin lubricant is excellent in abrasion resistance and chemical resistance. Therefore, by incorporating the fluororesin lubricant as a solid lubricant in the coating composition, it is possible to form a coating film having excellent lubrication performance for various members over a very wide range.

The content of the solid lubricant is preferably 20 parts by mass or more with respect to 100 parts by mass of the polyamide-imide resin. When the content is 20 parts by mass or more, better lubricity can be imparted to the coating film. The content of the solid lubricant is preferably 60 parts by mass or less with respect to 100 parts by mass of the polyamide-imide resin. When the content is 60 parts by mass or less, the content of the polyamide-imide resin or the like is relatively large, so that the adhesion between the coating film and the object to be coated is improved.

[Carbon black]
Carbon black is not particularly limited as long as it can impart conductivity to the coating film and reduce the surface resistivity of the coating film, but for example, conductive carbon such as acetylene black or graphitized carbon black. It is preferably black.

Examples of carbon black include Raven 420 (manufactured by Colombian Carbon Japan), Special Black No. 5 (manufactured by Degussa Japan), Denka Black (manufactured by Denka), Ketjen Black 300J (manufactured by Lion Specialty Chemicals), Ketjen Black 600JD (manufactured by Lion Specialty Chemicals), Imerys 250P, etc. .. Among them, carbon black, which can reduce the surface resistivity of the coating film and has little effect on the lubricity of the coating film, is preferable. For example, Ketjen Black 600JD (manufactured by Lion Specialty Chemicals) is commercially available. And can be suitably used. The carbon black may be used alone or in combination of two or more.

The content of carbon black is 1.7 parts by mass or more and 5.3 parts by mass or less with respect to 100 parts by mass of the polyamide-imide resin. If the content of carbon black is less than 1.7 parts by mass, sufficient conductivity cannot be imparted to the coating film. On the other hand, when the content of carbon black exceeds 5.3 parts by mass, the lubricity of the coating film is lowered.

The carbon black content is preferably 1.9 parts by mass or more. The content of carbon black is preferably 4.5 parts by mass or less, more preferably 3.5 parts by mass or less, and further preferably 2.5 parts by mass or less.

[Inorganic filler]
The inorganic filler is not particularly limited as long as it can impart wear resistance to the coating film, and examples thereof include metal oxides such as iron oxide, aluminum oxide, zinc oxide, titanium oxide, and silicon oxide. Can be done. It is preferably iron oxide or aluminum oxide. In particular, plate-shaped iron oxide is particularly preferable from the viewpoint of further improving the wear resistance of the coating film. As the plate-shaped iron oxide, for example, BM-200P (plate-shaped iron oxide manufactured by Titan Kogyo Co., Ltd.) is commercially available.

The content of the inorganic filler is 5 parts by volume or more and 25 parts by volume or less with respect to 100 parts by volume of the solid lubricant. When the amount of the inorganic filler is 5 parts by volume or more and 25 parts by volume or less, a certain range of the inorganic filler is present in the coating film, and the wear resistance of the coating film can be improved.

If the content of the inorganic filler is less than 5 parts by volume, sufficient wear resistance cannot be imparted to the coating film. On the other hand, if the content of the inorganic filler is more than 25 parts by volume, the lubricity of the coating film is lowered.

[solvent]
As the solvent, a solvent capable of dissolving the polyamide-imide resin is used as the main solvent, and if necessary, it can be mixed with an arbitrary solvent and used. Specifically, examples of the main solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide and the like.

[Other additives]
The coating composition of the present invention may contain additives usually blended in the coating composition, if necessary. Examples of the additive include a surfactant, a dispersant, a surface conditioner, an antifoaming agent, a hard cake inhibitor and the like, and these additives can be arbitrarily selected and blended. In addition, the contents of these various additives can be arbitrarily determined according to the required performance.

≪Manufacturing method of paint composition≫
The method for producing the coating composition of the present invention is not particularly limited, and the coating composition can be produced by a known method. For example, it can be obtained by blending a predetermined amount of each of the above-mentioned components, that is, a solid lubricant, a polyamide-imide resin, carbon black, and an inorganic filler in a solvent, subjecting them to stirring treatment, and then uniformly dispersing them. Can be done.

The method for uniformly dispersing each component is not particularly limited, but each component is uniformly stirred in a solvent containing N-methyl-2-pyrrolidone as a main component, and then physically subjected to shearing force to disperse the components. It is preferable, and for example, a method of dispersing by a dispersing device such as a three-roll mill or a bead mill can be mentioned.

≪How to form a coating film≫
The method of forming the coating film using the coating composition is not particularly limited, but for example, a method of uniformly coating the coating film so that the dry film thickness is within a predetermined range by air spray coating. Can be mentioned.

The object on which the coating film is formed can be made of iron-based or non-ferrous metal, and its shape does not matter. From the viewpoint that the coating composition of the present invention can improve the mold releasability of a molded product with respect to the mold, it is preferable that the coating composition is a mold used for molding.

For example, when a coating composition is applied to an object by air spray coating or the like, the formed untreated coating film is cured by firing. The coating film can be fired by a normal method for firing a coating film, for example, hot air heating, infrared heating, high frequency heating, or the like.

The firing temperature is not particularly limited, but can be appropriately set in the range of, for example, 200 ° C. or higher and 400 ° C. or lower, preferably 360 ° C. or higher and 380 ° C. or lower. In particular, by setting the firing temperature to 360 ° C. or higher, a resin having a high melting point such as polytetrafluoroethylene (PTFE) can be melted. The firing time is not particularly limited, but can be appropriately set, for example, in the range of 10 minutes or more and 60 minutes or less, preferably 40 minutes or more and 60 minutes or less.

≪Tectorial membrane≫
The coating film formed by using the coating composition is a coating film containing a polyamide-imide resin, a solid lubricant, carbon black, and an inorganic filler. This coating film is a coating film that simultaneously satisfies lubricity, wear resistance, and conductivity.

The film thickness of the coating film is not particularly limited, but is preferably 0.5 μm or more, and more preferably 15.0 μm or more, from the viewpoint of imparting lubricity to the object. The upper limit is not particularly limited, but is preferably less than 50.0 μm from the viewpoint of processing time and processing cost.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<< Examples, Comparative Examples >>
(Manufacturing of carbon black base)
Polyamide-imide (PAI), carbon black (CB, manufactured by Lion Specialty Chemicals, Ketjen Black 600JD) (active ingredient 100%), and dispersant (alkyrol ammonium salt) are in the ratio shown in Table 1 below. As described above, the mixture was sufficiently stirred and dispersed in N-methyl-2-pyrrolidone (NMP), ethyl acetate (ethyl acetate), and isopropyl alcohol (IPA), respectively.

The stirring and dispersion was carried out using a bead mill. As the stirring and dispersing conditions by the bead mill, 80% of the vessel volume was filled with 1.4 L of φ1.5 mm steel beads as the dispersion medium, and 2-pass dispersion treatment was performed at a flow rate of 600 mL / min. As a result, carbon black bases 1 to 7 (denoted as "CB bases 1 to 7" in Table 1) were manufactured.

(Iron oxide / PTFE-based production)
Polyamide-imide (PAI), polytetrafluoroethylene as a solid lubricant, surfactant (fluorine-containing group-containing oligomer), and plate-shaped iron oxide (manufactured by Titanium Industry Co., Ltd., BM-200P) as an inorganic filler (effective) Ingredients 100%) and dispersant (alkyroleammonium salt) in the proportions shown in Table 2 below, N-methyl-2-pyrrolidone (NMP), ethyl acetate (ethyl acetate), and isopropyl alcohol (ethyl acetate), respectively. It was sufficiently stirred and dispersed in IPA).

The stirring and dispersion was carried out using a bead mill. As the stirring and dispersing conditions by the bead mill, 80% of the vessel volume was filled with 1.4 L of φ1.5 mm steel beads as the dispersion medium, and 1-pass dispersion treatment was performed at a flow rate of 600 mL / min. As a result, inorganic filler solid lubricant bases 1 to 6 (denoted as "filler lubrication bases 1 to 6" in Table 2) were manufactured.

(Manufacturing of paint composition)
Using the carbon black bases 1 to 7 and the inorganic filler solid lubricant bases 1 to 6 produced as described above, the coating compositions of Examples and Comparative Examples were produced. Specifically, it was produced by mixing the combinations shown in Tables 3 and 4 below so that the carbon black base: the inorganic filler solid lubricant base = 1: 1 and stirring with dissolver stirring.

Tables 3 and 4 below show the volume parts of the inorganic filler with respect to 100 parts by volume of the solid lubricant (denoted as "content of the inorganic filler" in Tables 3 and 4) and the polyamide-imide resin 100 in the produced coating composition. The parts by volume of carbon black with respect to the parts by volume (denoted as "CB content" in Tables 3 and 4) are shown respectively. In all the coating compositions, the content of the solid lubricant was 40 parts by mass with respect to 100 parts by mass of the polyamide-imide resin.

<Evaluation>
[Lubrication test]
A lubricity test was conducted using the prepared coating compositions of Examples and Comparative Examples. Specifically, a friction and wear tester (friction player) (Friction Player FRP-2100, manufactured by Reska Co., Ltd.) was used to measure the friction coefficient of the coating film formed by applying the coating composition.

As a method for forming the coating film, the coating composition was applied to the surface of SUS304 (surface # 2000 polishing) by an air spray method, and the coating film was formed at a firing temperature of 360 ° C. and a firing time of 40 minutes. The film thickness of the coating film was 20 μm.

The setting conditions for measuring the coefficient of friction are: sliding form: pin-on disk (pin: Φ5 mm SUS304 disc: SUS304), load: 29.4 N (3 kgf), embroidery speed: 0.8 m / s, rotating circle diameter: 30 mm, Test time: 60 minutes. Then, the lubricity of the coating film was evaluated according to the following evaluation criteria based on the change in the average friction coefficient with respect to the measurement time of the coating film. The evaluation results are also shown in Tables 3 and 4 below. Further, FIG. 1 shows a graph showing a change in the friction coefficient with respect to the measurement time in the measurement of the friction coefficient of the coating film formed by the coating compositions of Example 1, Comparative Example 1 and Comparative Example 34.

(Evaluation criteria for lubricity)
Lubricity was evaluated by measuring the friction coefficient of the coating film over time and confirming the change in the friction coefficient over time. Specifically, the evaluation was made according to the following criteria.
◯: The coefficient of friction is stable over time, and the increase is small.
Δ: The coefficient of friction is not stable over time and rises significantly.
X: The coefficient of friction is not stable over time, and the increase is extremely large.

As examples of the evaluation criteria, as shown in Tables 3 and 4 below, in the coating film formed by the coating composition of Example 1, the friction coefficient is stable over time and the increase in the friction coefficient is small. The lubricity could be evaluated as "○" (see also FIG. 1). Further, in the coating film formed by the coating composition of Comparative Example 34, the friction coefficient was not stable over time and the increase in the friction coefficient was extremely large, and the lubricity was evaluated as “x” (Fig.). See also 1). If the lubricity is evaluated as "Δ", for example, the friction coefficient is once stable at the initial stage, but it is not as stable as the friction coefficient of the coating film of Example 1, and the friction coefficient is not as stable as that of the coating film. This is the case when the rise is large.

[Abrasion resistance test]
Abrasion resistance tests were carried out using the prepared coating compositions of Examples and Comparative Examples. The wear depth of the coating film after the above-mentioned lubricity test was confirmed by measuring the wear depth with a surface roughness meter. Abrasion resistance was evaluated according to the following evaluation criteria. The evaluation results are also shown in Tables 3 and 4 below.

(Evaluation criteria for wear resistance)
The wear resistance was evaluated according to the following criteria based on the measurement results of the wear depth of the coating film.
◯: The wear depth of the coating film after the lubricity test was 1 μm or less.
Δ: The wear depth of the coating film after the lubricity test is larger than 1 μm, but the substrate is not exposed.
X: The exposure of the substrate was confirmed on the coating film after the lubricity test.

[Conductivity test]
A conductivity test was carried out using the prepared coating compositions of Examples and Comparative Examples. Specifically, the coating composition was applied onto a glass plate by an air spray method to form a coating film having a film thickness of 20 μm at a firing temperature of 360 ° C. and a firing time of 40 minutes. The surface resistivity was measured using a meter. The evaluation results are also shown in Tables 3 and 4 below.

(Evaluation criteria for conductivity)
The conductivity was evaluated according to the following criteria based on the measurement results of the surface resistivity of the coating film.
○: surface resistivity of 1.00 × 10 ⁹ Ω / □ under the applied voltage 10V.
Δ: The surface resistivity at an applied voltage of 10 V is 1.00 × 10 ⁹ Ω / □ or more and ^{less than 1.00 × 10 11} Ω / □.
X: The surface resistivity at an applied voltage of 10 V is 1.00 × 10 ¹¹ Ω / □ or more.

From Tables 3 and 4, the coating film formed by the coating composition of the example was evaluated as "○" in the lubricity test, the abrasion resistance test, and the conductivity test, and the lubricity and the abrasion resistance were evaluated. , And it can be seen that the coating film simultaneously satisfies the conductivity. Further, also from the friction coefficient with respect to the measurement time in FIG. 1, the coating film made of the coating composition of Example 1 was compared with the coating film of Comparative Example 34 having a large content of inorganic filler and carbon black. Therefore, it can be seen that the coating film exhibits stable and excellent lubricity with little blurring.

On the other hand, the coating composition of the comparative example was evaluated as "Δ" or "x" in any of the lubricity test, the abrasion resistance test, and the conductivity test, and did not have sufficient characteristics.

Further, the coating film made of the coating composition of Comparative Example 1 containing no inorganic filler and carbon black has improved lubricity as compared with the coating film made of the coating composition of Example 1, but has resistance to resistance. The wear resistance and conductivity were lowered, and the lubricity, wear resistance, and conductivity were not satisfied at the same time.

≪About selection of inorganic filler≫
The above carbon black base 1 (carbon black content 0% by mass) and the inorganic filler solid lubricant bases 1 to 18 are used and blended so that the carbon black base: the inorganic filler solid lubricant base = 1: 1. , The coating compositions of Test Examples 1 to 18 were produced by stirring with dissolver stirring.

Here, the inorganic filler solid lubricant bases 1 to 6 use plate-shaped iron oxide as the inorganic filler. The inorganic filler solid lubricant bases 7 to 12 use amorphous iron oxide (manufactured by LANXESS, Biferrox 303T) instead of the plate-shaped iron oxide in the inorganic filler solid lubricant bases 1 to 6. Is. The inorganic filler solid lubricant bases 13 to 18 use plate-shaped aluminum oxide (manufactured by Kinsei Matek Co., Ltd., Seraph 10030) instead of the plate-shaped iron oxide in the inorganic filler solid lubricant bases 1 to 6. is there.

Then, the "average friction coefficient" was measured by forming a coating film and performing a "lubrication test" in the same manner as the coating compositions of the above-mentioned Examples and Comparative Examples. In addition, the peritoneal hardness (4H-9H) was measured by performing "scratch hardness (pencil method)" based on a method based on JIS K5600-5-4. The measurement results are shown in Table 5 below. The "content" in Table 5 means the volume part of the inorganic filler with respect to 100 parts by volume of the solid lubricant.

From Table 5, as the coating film with the coating composition of Test Examples 1 to 6 using "plate-shaped iron oxide" as the inorganic filler, "atypical iron oxide" or "plate-shaped aluminum oxide" was used as the inorganic filler. It was found that the pencil hardness tended to be higher and the friction coefficient tended to be lower than that of the coating film made of the coating compositions of Test Examples 7 to 18. In particular, Test Example 6 (plate-shaped iron oxide) and Test Example 12 (atypical iron oxide) were contained so that the volume of the inorganic filler was 50 parts by volume with respect to 100 parts by volume of the solid lubricant. And, in comparison with Test Example 18 (plate-shaped aluminum oxide), according to the coating composition of Test Example 6 (plate-shaped iron oxide), the coating showing the highest pencil hardness and the lowest friction coefficient. A film was formed.

From the above test results, it was confirmed that it is particularly preferable to use plate-shaped iron oxide as the inorganic filler.

Claims (3)

A coating composition used for a mold release process for a mold used for a molding process.
Contains a polyamide-imide resin, a solid lubricant, carbon black, an inorganic filler, and a solvent.
The content of the inorganic filler is 5 parts by volume or more and 25 parts by volume or less with respect to 100 parts by volume of the solid lubricant.
Wherein Ri Der below 5.3 parts by mass or more 1.7 parts by content with respect to the polyamide-imide resin 100 parts by weight of carbon black,
A coating composition in which the content of the solid lubricant is 20 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the polyamide-imide resin. The coating composition according to claim 1, wherein the inorganic filler is a plate-shaped iron oxide. The coating composition according to claim 1 or 2 , wherein the solid lubricant is a fluororesin lubricant.

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