JPH0510990B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method of forming a coating film of polycyanoaryl ether on the surface of various substrates, and more specifically, to a method of forming a coating film of polycyanoaryl ether on the surface of various substrates. The present invention relates to a method for forming a cyanoaryl ether coating. [Technical background of the invention and its problems] Metal substrates, particularly those made of steel, aluminum, and copper, are coated with various resins on their surfaces in order to impart corrosion resistance and electrical insulation. Forming a film is being carried out. The methods for forming resin coatings at this time can be roughly divided into two methods: one is to apply a resin liquid prepared by dissolving the resin in an appropriate solvent onto the surface of the substrate (solution coating method), and the other is to apply resin powder to the surface of the substrate. A method of coating by heating the entire surface and melting the resin (powder coating method)
is being put into practice. By the way, among resins, polycyanoaryl ether is relatively superior in heat resistance, solvent resistance, electrical insulation, mechanical strength, etc. compared to other resins, so polycyanoaryl ether is used as a base material as described above. Components coated with ether have superior functionality compared to components coated with other resin coatings, and can be expected to be widely used in industrial fields such as machinery and metals. However, the above-mentioned useful properties of this polycyanoaryl ether function as a disadvantageous factor when forming a coating film. That is, excellent solvent resistance means that it is difficult to dissolve in a solvent, which makes it difficult to apply the solution coating method described above. In addition, excellent heat resistance makes it difficult to apply the powder coating method described above. For these reasons, a practical method for forming a polycyanoaryl ether coating film having useful properties is still unknown. [Object of the Invention] The object of the present invention is to provide a method for forming a polycyanoaryl ether coating film on the surface of various substrates. [Summary of the Invention] As a result of intensive research to form a polycyanoaryl ether coating film by the powder coating method described above, the present inventors have discovered that a polycyanoaryl ether having a specific structure as described below is used as the polycyanoaryl ether. This book discovered the fact that by applying the coating conditions described below, it was possible to form a uniform and smooth coating film with excellent mechanical strength as well as heat resistance, solvent resistance, and electrical insulation properties. We have now developed an inventive method. That is, the method for forming the polycyanoaryl ether coating film of the present invention is as follows:

[Formula] (In the formula, Ar is

【formula】

【formula】

Contains 50 mol% or more of repeating units represented by [Formula] and p-
The reduced viscosity (ηsp/c) at 60℃ of a solution with a concentration of 0.2 g/dl using chlorphenol as a solvent is 0.3~
2.0 dl/g of polycyanoaryl ether powder with an average particle size of 10 to 300 μm is attached to the surface of the substrate, heated to a temperature of 360 to 450°C to melt and fluidize the powder, and then cooled. It is characterized by In the method of the present invention, first, polycyanoaryl ether powder, which will be described later, is uniformly adhered to the surface of the substrate. The polycyanoaryl ether used contains 50 mol% or more of the above repeating units, and the terminals are -H,
-Introduced from OH, halogen, or the molecular weight regulator described below

【formula】

【formula】

【formula】

It has a molecular structure blocked by a group such as [Formula]. If the content of the above-mentioned repeating units is less than 50 mol%, the heat resistance and solvent resistance will decrease, reducing the usefulness of the coating film. This polycyanoaryl ether has the above-mentioned repeating unit as a main component, but in addition,

If it is a repeating unit represented by the formula, it may be contained as long as it is less than 50 mol%. However, here, Ar′ is, for example,

【formula】

【formula】

【formula】

【formula】

【formula】

We can give something like [Formula]. In addition, the degree of polymerization of this polycyanoaryl ether is determined by dissolving this resin in p-chlorophenol to make a resin liquid with a concentration of 0.2 g/dl, and the reduced viscosity (ηsp/c) at 60°C of this resin liquid is 0.3~ 2.0
The degree of polymerization is such that dl/g. ηsp/c is 0.3
Polycyanoaryl ethers with less than dl/g are low molecules and the mechanical strength of the coating film is low, and polycyanoaryl ethers with ηsp/c of more than 2.0 dl/g are polymers. As a result, workability during coating film formation deteriorates, and it becomes extremely difficult to form a smooth coating film with uniform thickness. Such polycyanoaryl ethers include, for example, benzonitrile, hydroquinone, 4,
Divalent phenols represented by HO-Ar-OH (wherein Ar has the same meaning as above) such as 4'-biphenol and 2,7-dihydroxynaphthalene may be used alone or with HO-Ar'-OH (however, alkali metal salts such as sodium carbonate, potassium carbonate, and sulfolane, together with less than 50 mol % of other dihydric phenols, denoted by Ar′ has the same meaning as above);
The reaction is carried out in the presence of a solvent such as N-methyl-2-pyrrolidone, dimethylacetamide, dimethylsulfoxide, diphenylsulfone, and finally water,
It can be easily synthesized by treatment with alcohol. In this synthesis process, benzonitrile and dihydric phenol should be charged in approximately equimolar amounts, and in order to adjust the molecular weight, cumylphenol, p-tacybutylphenol, p-phenylphenol, Containing a certain amount of monovalent phenol such as cyanophenol,
Alternatively, reaction conditions such as reaction temperature and reaction time may be appropriately selected. This polycyanoaryl ether has an average particle size of 10
Used as a powder of ~300μm. Preferably 10
~200 μm. When used as a powder with an average particle diameter of less than 10 μm, the powder scatters and floats violently during the operation of adhering the powder to a substrate, resulting in extremely poor workability. On the other hand, if a powder with an average particle size larger than 300 μm is used, the series of phenomena of melting and fluidization of the powder will not proceed smoothly during the melt flow treatment described below, and the surface of the coating film formed will be damaged. Unevenness occurs and the surface is not smooth. The powder may be attached to the base material by spreading the powder to a predetermined thickness and placing it on the surface of the base material. Note that prior to this operation, it is effective to roughen the surface of the substrate by, for example, sandblasting, as this will improve the adhesion between the coating film to be formed and the surface of the substrate.
Furthermore, heating the substrate to a temperature below the melting point of the powder is advantageous in terms of handling, since the powder softens during adhesion. In the method of the present invention, next, the base material to which the powder has adhered is heated to 360 to 450°C to melt and fluidize the powder. If the temperature is less than 360℃, the powder will not melt properly and fluidity will deteriorate, resulting in a smooth coating film.If the temperature is higher than 450℃, the coating will be colored and its appearance will deteriorate. causing a decline. The preferred temperature is 380-430°C. Finally, the whole is cooled to solidify the molten fluid film on the surface of the base material. The cooling treatment may be either gradual cooling or rapid cooling. For example, when a slow cooling treatment such as cooling in air is performed, the crystallized structure of polycyanoaryl ether is sufficiently developed to form a coating film with high mechanical strength. On the other hand, when the material is rapidly cooled at a cooling rate of 50° C./second or higher, another advantage is obtained in that it becomes possible to form a coating film with excellent transparency because the crystallized structure is not sufficiently developed. [Examples of the invention] Example 1 (1) Production of polycyanoaryl ether In a separable flask with an internal volume of 5, 2,6
- Put 215 g of dichlorobenzonitrile, 136.3 g of hydroquinone, 207 g of potassium carbonate, 2.5 g of sulfolane, and 1 part of toluene, and heat at 160° C. for 1.5 hours while blowing argon gas.
Then, the temperature was raised to 200°C and the polymerization reaction was continued for 2 hours. After the reaction was completed, a large amount of water was added thereto to precipitate and collect the polymer powder. The repeating unit of this polymer is

[Formula] and its ηsp/c was 1.51 dl/g. The glass transition temperature (Tg) of this polymer is 180
The thermal decomposition temperature (Td) was 530°C (in air), and the volume resistivity was 2×10 ¹⁶ Ωcm. Additionally, this polymer was flame retardant and insoluble in acetone, ethanol, toluene, chloroform, and methylene oxide solvents. (2) Formation of coating film First, the surface of a 3 mm thick Al plate was subjected to sandblasting to roughen the surface with an average depth of undulations of 10 μm and an average period between undulations of 15 μm. On top of this, the above polymer powder having an average particle size of 40 μm was spread to a thickness of 5 mm, and the whole was kept in an oven at 390° C. for 20 minutes. Then, it was taken out of the oven and allowed to cool in the air. A smooth coating film was formed on the surface of the Al plate. (3) Properties of the paint film The paint film formed in (2) was visually observed to check for pinholes and surface smoothness.
The adhesion strength with the Al plate was measured. Adhesion strength is T
It was measured as mold peel strength. The results are shown in the table. In addition, the quality of workability during coating film formation is also noted in the table. Example 2 232.5 g of 4,4'-biphenol was used in place of 136.3 g of hydroquinone, and 200 g of 4,4'-biphenol was used during the polymerization reaction.
A polymer was synthesized in the same manner as in Example 1, except that the reaction time at °C was 1.5 hours. The repeating unit of this polymer is

[Formula], ηsp/c is 1.23dl/g, Tg is 216℃, Td is 520℃,
The volume resistivity was 2×10 ¹⁶ Ωcm. The solvent resistance and flame retardance were also equivalent to those of the polymer of Example 1. A coating film was formed in the same manner as in Example 1 using this polymer (average particle size: 30 μm). The properties of the coating film are shown in the table. Example 3 A polymerization reaction was carried out in the same manner as in Example 1, except that 233.2 g of 2,7-dihydroxynaphthalene, 1.3 g of sulfolane, and 0.7 g of toluene were used in place of 136.3 g of hydroquinone, 2.5 g of sulfolane, and 1 g of toluene. . The repeating unit of the obtained polymer is

[Formula] and ηsp/c was 0.8 dl/g. Tg215℃, Td524
℃, volume resistivity 3×10 ¹⁶ Ωcm. Moreover, both solvent resistance and flame retardancy were equivalent to those of Example 1. A coating film was formed in the same manner as in Example 1 using this polymer (average particle size: 30 μm). The properties of the coating film are shown in the table. Comparative Example 1 A polymer with ηsp/c of 0.28 dl/g was obtained by changing the reaction time at 200° C. in Example 1 to 0.5 hours. A coating film was formed in the same manner as in Example 1 using this polymer powder having an average particle size of 20 μm. The resulting coating film was so brittle that it was impossible to measure its peel strength. The properties are shown in the table. Comparative Example 2 A polymer with ηsp/c of 2.5 dl/g was obtained by changing the reaction time at 200° C. in Example 1 to 3 hours. A coating film was formed in the same manner as in Example 1 using this polymer powder having an average particle size of 100 μm. The resulting coating film had significant surface irregularities and was not a smooth coating film. Comparative Example 3 The polymer powder obtained in Example 1 was pulverized using a blender manufactured by Warning Co., Ltd., and the average particle size was
Formation of a coating film was attempted in the same manner as in Example 1 using a material with a diameter of 5 μm. In this case, the scattering of polymer particles was large and the coating workability was extremely poor. Comparative Example 4 In Example 1, the polymer was obtained in the form of a lump without injecting water into the polymerization reaction product, and then this was pulverized using a Warning blender to obtain a polymer with an average particle size of 350 μm. Particles were obtained. A coating film was formed in the same manner as in Example 1 using these polymer particles. In this case, the resulting coating film had many irregularities and pinholes, and was poor in practical use. Comparative Example 5 Using the polymer powder obtained in Example 1,
A coating film was formed in the same manner as in Example 1, except that the fluidization temperature during coating film formation was 350°C. In this case, the melting of the polymer particles did not proceed sufficiently, and a homogeneous coating film could not be obtained. Comparative Example 6 Using the polymer powder obtained in Example 1,
A coating film was formed in the same manner as in Example 1, except that the fluidization temperature during coating film formation was 470°C.
In this case, the color of the coating film was large and the appearance could not be said to be good.

【table】

[Table] [Effects of the invention] As is clear from the above explanation, the method of the present invention has the following effects:
Polycyanoaryl ether coatings with excellent heat resistance, solvent resistance, electrical insulation properties, and high mechanical strength can be formed on the surfaces of various substrates with good adhesion, making them suitable for use in various industrial fields, especially machinery. ,
The present invention is useful when manufacturing members that require various functions in the field of metals.

Claims (1)

[Claims] Primary formula: [Formula] (wherein Ar represents any one of [Formula] [Formula] [Formula]) containing 50 mol% or more of repeating units and p-
The reduced viscosity (ηsp/c) at 60℃ of a solution with a concentration of 0.2 g/dl using chlorphenol as a solvent is 0.3~
2.0 dl/g of polycyanoaryl ether powder with an average particle size of 10 to 300 μm is attached to the surface of the substrate, heated to a temperature of 360 to 450°C to melt and fluidize the powder, and then cooled. A method for forming a polycyanoaryl ether coating film characterized by: