JPH0314043B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for forming a fluorine-containing polymer compound coating with excellent durability. Conventionally, in order to form a fluorine-containing organic polymer film on the surface of inorganic and organic substrates such as various metals, glass, and organic polymer compounds, the substrate is placed in a fluoroalkene or fluoroalkane atmosphere and glow discharge is performed. Plasma polymerization is carried out by this method. For example, as disclosed in JP-A-55-99932, surface hardness and hydrophobicity can be improved by introducing fluorine into the surface of an organic polymer compound by bringing it into contact with fluorine-containing plasma. , aiming to improve chemical resistance, etc. However, when the hardness of the fluorine-containing organic polymer coating formed by the above conventional method was tested using a loaded steel ball, the coating was easily damaged, and when the contact angle with water was measured after being immersed in an organic solvent or water. It was found that the durability was extremely poor. An object of the present invention is to provide a method for forming a fluorine-containing polymer compound coating with improved coating strength. Another object of the present invention is that not only the solvent resistance and water resistance are superior to conventional coatings at the initial value, but also that the contact angle of water after the test is only slightly reduced by about 97 to 98%. It is an object of the present invention to provide a method for forming a fluorine-containing polymer compound film that is extremely durable and can maintain such a high contact angle. The present invention comprises (a) forming a fluorine-containing polymer compound film on the substrate by placing the substrate in an atmosphere of fluoroalkene and/or fluoroalkane and performing glow discharge, and (b) optionally, Subsequently, the thickness of the formed coating is increased by placing the substrate on which the coating has been formed in a higher pressure atmosphere of fluoroalkene and/or fluoroalkane, and (c)
The present invention relates to a method for forming a highly durable fluorine-containing polymer compound coating on a substrate, which is characterized by heat-treating the substrate on which the coating has been formed. In the present invention, the coating strength is improved by carrying out an extremely simple operation of bringing the substrate into contact with fluorine-containing plasma to form a fluorine-containing polymer compound coating on the surface, and then heat-treating the substrate. Not only is the solvent resistance and water resistance improved by a few percent compared to the initial value without heat treatment, but also
Surprisingly, it was revealed that the properties hardly deteriorated even after solvent resistance and water resistance tests, and that it had an extremely high retention rate of 97 to 98% or more. The reason for this is not yet fully understood, but it is probably because relatively low molecular weight substances in the fluorine-containing polymer compound are removed by heat treatment, or the crosslinking reaction of the formed fluorine-containing compound is induced and completed. This is thought to be due to the disappearance of free radicals or the disappearance of free radicals. In the present invention, inorganic and organic base materials are used as the base material. Examples of the former include all inorganic base materials such as metals or alloys such as iron, copper, aluminum, and stainless steel, glass, and ceramics. Examples of the latter include various base materials such as polyolefin, polyacrylate, polyamide, polyimide, polyester, epoxy resin, polyvinyl chloride, polycarbonate, polyvinyl alcohol, and polystyrene. A preferable example of the fluoroalkene used in the present invention is a compound in which one or more hydrogens of a linear, branched, or cyclic alkene having 2 to 15 carbon atoms is replaced with fluorine, preferably half or more of the hydrogens. Examples include compounds in which is replaced with fluorine, most preferably all hydrogens are replaced. A part of hydrogen may be replaced with chlorine, bromine, or iodine. Specific _examples include _C2F4 (tetrafluoroethylene), _{C3F6 , C4F8 , C2H3F , C2HF3 , C2ClF3 ,}
Examples include CF ₂ =CH ₂ . In the present invention, preferred fluoroalkane is a compound in which one or more hydrogens of a linear, branched, or cyclic alkane having 1 to 10 carbon atoms is replaced with fluorine, preferably half or more of the hydrogens are replaced with fluorine. Substituted compounds, most preferably the number of hydrogens is 0
~2 and the others are fluorine-substituted compounds. A part of hydrogen may be replaced with chlorine, bromine, or iodine. Specific examples include CF ₄ , CBrF ₃ ,
_{CCl2F2 , CCl3F} , _CHClF2 , _CHCl2F , _CHF3 ,
C ₂ F ₆ , CCl ₂ FCCl ₂ F, CCl ₂ FCClF ₂ , CH ₃ CClF ₂ ,
_{CH3CHF2 , C3F8 , C4F10} , _{cyclo - C4F8} , _{C5F12 ,}
Examples include C ₆ F ₁₄ , C ₈ F ₁₈ , C ₁₀ F ₂₂ and the like. It is also possible to use the above-mentioned fluoroalkenes and fluoroalkanes in combination, and each can be used alone or in a mixture of two or more. In the present invention, glow discharge is performed by placing a base material in an atmosphere of the above-mentioned fluoroalkene and/or fluoroalkane. There is no particular limit to the flow rate of the fluoroalkene and/or fluoroalkane, but it is usually about 0.1 to 20 STP cm ³ / per volume of the discharge area.
It is preferable to set it to min. It is also optional to mix an inert gas into the glow discharge region. Glow discharge can be performed according to a known method, for example -10 to 80
℃, preferably a temperature of 0 to 40℃, 0.05 to 2 Torr,
Preferably, an atmosphere of 0.1 to 0.5 Torr is placed under a high frequency electric field of 0.1 to 100 MHz with a discharge power of 2 to 50 W per container. Although both an external electrode type and an internal electrode type can be used as the apparatus, the former is more preferable since no polymer is produced on the electrodes. Next, in the present invention, if necessary, the thickness of the formed coating can be increased by subsequently placing the substrate on which the coating has been formed in a higher pressure atmosphere of fluoroalkene and/or fluoroalkane. Higher pressure is preferably 1-2 atm
The film thickness can be increased approximately 2 to 10 times by applying this pressure for approximately 0.5 to 10 hours. In the present invention, the strength and durability of the coating can be significantly improved by heat-treating the substrate on which the coating has been formed. The conditions for heat treatment can be selected depending on the heat resistance of the base material and the heat resistance of the fluorine-containing polymer compound, and the temperature can generally be selected in the range of 50 to 700℃, and the treatment time can be selected at lower temperatures within this temperature range. It is appropriate to shorten it as the temperature increases, and usually
It is preferable to set it as the range of about 0.5 seconds - 7 days. Heat resistance of the base material For example, when the softening point or decomposition temperature is below about 200℃, it is best to determine according to the heat resistance of the base material, and when the heat resistance of the base material is about 200℃ or above, it is better to determine according to the heat resistance of the base material. The heat treatment temperature and time are preferably selected according to the heat resistance of the compound. Specifically, if the base material is steel, it will be about 200 to 400℃, and if the base material is glass, it will be about 150 to 300℃.
℃, about 100-200℃ for polyester, about 150-300℃ for polyamide, about 50-300℃ for polyacrylate
The temperature is preferably about 150°C, and about 80 to 200°C for polyolefins. Although the heat treatment process can be performed in air, it is preferable to perform it in an inert gas such as nitrogen, helium, or argon. A polymer compound coating can be obtained. As described above, the present invention improves the properties of a fluorine-containing polymer compound coating formed by glow discharge, and it is possible to improve the properties of the fluorine-containing polymer compound coating by changing the raw materials and glow discharge polymerization conditions for forming the fluorinated polymer compound coating. It can be applied regardless of the type of substrate, and can be applied regardless of the type of substrate, except that the treatment temperature, treatment time, and if necessary, the treatment atmosphere are adjusted depending on the type of substrate. Next, the present invention will be explained with reference to Examples and Comparative Examples. In the following, the hardness, solvent resistance, and water resistance of the coating were measured by the following methods. 1. Hardness of the film: A base material on which a film with a thickness of 0.5 ± 0.1 μm has been formed is placed horizontally with the film side facing up, and placed on top of it so as not to move horizontally or rotate. A load of 200 g is applied to a polished steel ball with a diameter of 8 mm, which is fixed and whose weight including accessories is offset. Next, the coating surface was moved along a straight line in a horizontal plane for 20 mm at an average speed of 160 mm/min, and then it was visually observed whether the coating was damaged or not. The evaluation was based on the following criteria. 〇...There may be no scratches on the coating, or there may be scratches on the coating, but the coating will not be damaged.
The base material surface has not yet appeared. ×...The coating is damaged and the base material surface is exposed. 2 Solvent resistance The test object was exposed to the test liquid carbon tetrachloride or 1,
Sufficient contact is made using ultrasound for a predetermined time in 1,2-trichloro-1,2,2-trifluoroethane. Next, remove the test object from the test liquid,
After drying at 70-80°C for 1 hour, the contact angle of the film with water was measured. Ultrasonic contact was carried out using Pet Cleaner (manufactured by Ultrasonic Industry Co., Ltd.) at a frequency of 41 kHz and 35 W. The thickness of the coating was measured using Talystep (manufactured by Taylor Hobson), and the contact angle was measured using a goniometer (manufactured by Elma Optical Co., Ltd.). 3 Water resistance After immersing the test object in water for 24 hours, 70-80℃
After drying for 1 hour, the contact angle with water was measured. The contact angle was measured in the same manner as described above. Examples 1 to 8 and Comparative Example 1 A stainless steel plate (SUS-
304, length 100mm, width 50mm, thickness 1mm),
10STP _{of C2F4} gas after pumping down to 0.05Torr
Adjust the flow pressure to 0.15 Torr at cm ³ /min,
When 50W of 13.56MHz high-frequency power was applied to the electrode to generate plasma and treated for 30 minutes, the thickness
A film of 0.4 μm was formed. Next, the plasma reaction tube was filled with C ₂ F ₄ to atmospheric pressure and after 30 minutes, the thickness of the film became 0.6 μm. The stainless steel plate treated in this way was
Heat treatment was performed at a predetermined temperature and time in the atmosphere listed in the table. The results are shown in Table 1. Note that solvent resistance indicates the contact angle with water after washing in carbon tetrachloride for 15 minutes. Furthermore, as Comparative Example 1, the results were also shown where no heat treatment was performed.

[Table] Test Example 1 The film-formed stainless steel plates obtained in Example 3 and Comparative Example 1 were treated with 1,1,2-trichloro-1,
Solvent resistance was measured by immersing the sample in 2,2-trifluoroethane for 30 minutes. The results are shown in Table 2.

[Table] Examples 9 to 11 and Comparative Example 2 Films were formed and tested in the same manner as in Examples 1 to 8. However, the difference is that instead of the stainless steel plate, a glass plate (1 mm thick, length
50mm, width 20mm) are placed side by side and subjected to plasma treatment.
The difference is that the duration was changed to 45 minutes instead of 30 minutes. Note that (a) the thickness of the film after the process is 0.4 μm, and (b) the thickness of the film after the process is
It was 0.6 μm. The results are shown in Table 3.

[Table] Example 12 and Comparative Example 3 Polymethyl methacrylate sheet (length 50 mm,
(width 20mm, thickness 8mm), high frequency power of 30W,
Examples 1 to 8 except that the plasma treatment was changed to 45 minutes
A film was formed in the same manner as above, and its water resistance (24 hours) was measured. The results are shown in Table 4.

[Table] Example 13 A film-formed stainless steel plate obtained in the same manner as in Example 1 except that the film thickness increasing step corresponding to step (b) of the present invention was omitted had a film thickness of 0.3μ.
The coating hardness, solvent resistance, and water resistance were the same as in Example 1, except that m.

Claims (1)

[Scope of Claims] 1 (a) A film of a fluorine-containing polymer compound is formed on a base material by placing the base material in an atmosphere of fluoroalkene and/or fluoroalkane and performing glow discharge, (b) Necessary (c) increasing the thickness of the formed coating by subsequently placing the coated substrate in a higher pressure atmosphere of fluoroalkenes and/or fluoroalkanes; A method for forming a highly durable fluorine-containing polymer compound coating on a substrate, which comprises heat-treating the formed substrate. 2. The method according to claim 1, wherein the base material is an inorganic base material. 3. The method according to claim 1, wherein the base material is an organic base material. 4 Claim No. 1 in which heat treatment is performed in an inert gas
The method described in section.