JPH069918B2 - Fluorine-containing resin coated body and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fluorine-containing resin coating, which has a surface having lubricity, releasability and water / oil repellency on various material substrates. It was done.

[Prior Art] Fluorine-containing resins such as tetrafluoroethylene resin (PTFE) have excellent properties such as lubricity, non-adhesiveness, water repellency, and oil repellency. Although it is used for various purposes, it has been attempted to impart these excellent physical properties to the surface of various other materials.
As a means therefor, a method of forming a film by means such as vacuum vapor deposition, a method of baking powder, a method of coating or the like are performed. However, each of these methods has problems. That is, since the material substrate is placed at a high temperature by means such as vacuum deposition of a fluorine-containing resin, this method cannot be applied unless it is a heat-resistant material.
Also in the method of baking the fluorine-containing resin powder, the material substrate is similarly limited. Further, in the method of coating, since a fluororesin which is easily dissolved in a solvent is selected, the lubrication performance, which is a characteristic of the fluororesin, is deteriorated.

[Means for Solving Problems] The present inventors have found that in order to obtain a product without problems by these conventional methods, it can be solved by selecting a fluororesin having a molecular weight as low as possible. The invention has been reached. That is, the present invention has an average molecular weight of 60 on the substrate.
A fluorine-containing resin coated body obtained by coating a fluorine-containing resin in the range of 0 to 1500, and its production method has an average molecular weight of
A method for producing a fluororesin-coated body characterized by coating the fluororesin on a substrate by a vacuum plating method using a fluororesin in the range of 600 to 1500 and an average molecular weight in the range of 600 to 1500 A method for producing a fluororesin-coated body, which comprises forming a coating film on a substrate with a solution prepared by dissolving a fluororesin in an organic solvent, and volatilizing the organic solvent.

The fluorine-containing resin in the present invention has a molecular weight of 600 to 1500.
Is a low molecular weight substance in the range of, and the present inventors have already proposed a method for producing a low molecular weight fluororesin powder of the submicron order, a fluororesin is heated and reacted in the presence of a fluorinated material, and a reaction occurs. A low molecular weight fluororesin obtained by a method of cooling and precipitating a lower molecular weight fluororesin contained therein from the produced gas (Japanese Patent Application No. 61-285962) can be preferably used. Hereinafter, the production of this fluororesin low molecular weight product will be described in more detail.

As the fluorine-containing resin as a raw material, PTFE, tetrafluoroethylene-hexafluoropropylene copolymer (FE
P), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVdF), polyvinyl fluoride (PV
A general-purpose fluorine-containing resin such as F) is preferably used, and powder,
Any shape such as pellets, sheets, scraps or fillers can be used, but it is faster to use those having a low molecular weight by a means such as a fluorinating agent, radiation or heating in advance.
The target low molecular weight product can be obtained in high yield. As the fluorinating agent, fluorine (F ₂ ) and nitrogen trifluoride (N
F ₃ ), chlorine trifluoride (ClF ₃ ), etc. are used, and the reaction conditions are different depending on the resin used, but the fluorine-containing resin of the raw material is heated more than fusion, and the ambient temperature is slightly lower than the raw material temperature of 200- It is performed at 550 ℃. When the ambient temperature is 200 ° C or lower, the low molecular weight fluoropolymer does not easily turn into a gas. Further, when the raw material temperature is 600 ° C. or higher and the atmospheric temperature is 550 ° C. or higher, the low molecular weight substance of the fluororesin in the reaction product gas is decomposed, so that the low molecular weight substance of the fluororesin cannot be obtained in good yield. The amount of the fluorinating agent used depends on the type and shape of the fluororesin, but as a fluorine atom relative to 100 parts by weight of the fluororesin.
It may be supplied (present) in an amount of 0.01 parts by weight or more, and if it is less than 0.01 parts by weight, the reaction for lowering the molecular weight does not easily proceed. On the other hand, when it is present in excess, the molecular weight of the fluorine-containing resin is too low, and the desired low molecular weight product cannot be obtained in good yield, so it is generally selected within a range of up to about 10 parts by weight. preferable. In this case, it is diluted with an inert gas such as nitrogen, argon, helium or carbon tetrafluoride.

Any reactor can be used as long as it is in a form in which gas and solid are in contact with each other.For example, a gas-solid contact such as a forced circulation type reactor equipped with a multi-stage reaction shelf and a fluidized bed can be used. A reactor that works well is preferred.

In order to obtain the low molecular weight product of the fluororesin in good yield, the high-temperature reaction product gas containing the low molecular weight product of the fluororesin in a gaseous state is cooled to 100 ° C or lower, preferably room temperature or lower, and the low molecular weight of the fluororesin Coolers and separators or collectors for depositing, separating or collecting material are needed. As a cooling method, air, water, a refrigerant, a liquefied gas, etc. are considered, and it is possible to control the particle size of the precipitated particles by controlling the cooling rate of the reaction product gas. As the method, a sedimentation chamber type utilizing gravity, a collision plate type utilizing inertial force, a cyclone utilizing centrifugal force, a back filter, etc. are adopted.
Further, the higher the pressure in the reactor, the faster the reaction proceeds, but at normal pressure it has a sufficient reaction rate. The low molecular weight substance of the fluorine-containing resin obtained by such a method is a fine spherical or flaky powder, and the particle diameter can be further reduced by increasing the cooling rate. In addition, since the product is decomposed in the presence of active fluorine radicals, the terminal is converted into CF ₃ and is extremely stable.

The molecular weight of the fluororesin obtained by this method can be easily adjusted by selecting the reaction temperature and the cooling temperature. Further, the low molecular weight fluororesin thus obtained is further vaporized by heating, and the heating temperature and cooling temperature are selected to obtain a fluororesin powder having a narrower molecular weight distribution.

As a method of coating the surface of various substrates with such a low molecular weight fluororesin powder, in the present invention, vacuum plating is performed using a fluororesin having an average molecular weight of 600 to 1500 as a target material. Various means such as vacuum deposition, sputtering, and ion plating can be used as the vacuum plating means, and the case of forming the fluorine-containing resin coating on the substrate by the vacuum deposition method will be specifically described below. Place the fluorine-containing resin powder whose molecular weight has been adjusted in advance in the vacuum vapor deposition device, and set the degree of vacuum in the device to 10 ^-6 ~
After setting to 10 ^-1 torr, the fluorine-containing resin powder is heated by a heating source such as a resistance heater. If the degree of vacuum in the equipment is lower than 10 ^-1 torr, the residual gas has a small mean free path of the fluorine-containing resin molecules and repeats collisions before reaching the substrate to be coated, growing into large particles and generating energy. Loses and falls. The higher the degree of vacuum, the better the vapor deposition, but it is difficult to reduce it to 10 ^-6 torr or less, and the average free path of air at 10 ^-4 torr is about 50 cm, so industrial vapor deposition is performed. 10 ^-4 torr is enough. The temperature of the vapor deposition source is in the range of 50 ~ 300 ℃, depending on the molecular weight of the fluororesin used, but if it is lower than 50 ℃,
Since the fluorine-containing resin is hard to vaporize and the molecular density in the device is low, vapor deposition takes time. Further, when the temperature is higher than 300 ° C., the fluorine-containing resin is easily vaporized, the molecular energy is large, and the vapor deposition proceeds rapidly. However, if the temperature is too high, the substrate may be deformed or deteriorated, or the control of the film thickness may become difficult, depending on the distance to the substrate and the vapor deposition time.

The distance between the fluororesin and the substrate depends on the device but is 5 to 50c.
A range of m is preferred. If it is larger than 50 cm, the fluorine-containing resin molecule loses energy and falls because the distance is too large as compared with the mean free path. The shorter the distance, the better, but if the distance is shorter than 5 cm, the substrate cannot withstand the radiant heat of the evaporation source, and is easily deformed or deteriorated. The material of the substrate targeted by the present invention is not particularly limited and may be any type of material, but the effect of the present invention is most exerted when the substrate is a material having no heat resistance. That is, when a low molecular weight fluorine-containing resin within the scope of the present invention is used, a uniform fluorine-containing resin film can be formed with the temperature of the substrate kept at about room temperature. A film excellent in various physical properties can be formed without being accompanied. As such a material, generally, there is a plastic material, and even if the base material itself is a heat-resistant material, it is a material having various functional thin films formed on the surface thereof, and the heat history is disliked. It is particularly effective for materials such as magnetic disks.

The vapor deposition time is in the range of several seconds to several tens of minutes. If the time is shorter than this, the formation of a film cannot be achieved, and if it is longer than this, crystals grow and a uniform film cannot be obtained.

By performing vapor deposition under the above conditions, a film thickness of several nm
A smooth film with a thickness of several μm can be obtained. The film thickness can of course be controlled by the vapor deposition time, but in order to perform strict control, the fluorine-containing resin should be vaporized by evaporating the entire amount, and the desired film thickness should be set appropriately according to the substrate area. Obtainable.

Although the method of coating by vacuum plating has been described above, the second method of the present invention, that is, the average molecular weight is 600
It is also possible to form a good coating film by a method of forming a coating film on a substrate with a solution prepared by dissolving a fluororesin in the range of to 1500 in an organic solvent and volatilizing the organic solvent. Fluorine-containing resins having an average molecular weight in this range can be dissolved in various solvents, but among them, 1,1,2-trichloro, which is a solvent that has excellent physical properties such as nonflammability and low toxicity, and is easily volatilized
-1,2,2-Trifluoroethane (CFC113) is one of the most preferred solvents. For example, in the case of a fluorine-containing resin having an average molecular weight of 700, this fluorocarbon 113 has 5 g /
About 100-100 g of Freon is dissolved, and a liquid film is formed by various means such as dipping, spraying, coating, and spin coating on various substrates using this solution, and naturally drying or, if necessary, heat drying. Thus, the solvent is volatilized, and the low molecular weight fluororesin dissolved in the solution is obtained as a uniform transparent film in close contact with the substrate. In this case, the CFC 113 is easily dried by volatilization naturally, so especially in the case of a material in which heat drying is inconvenient,
It is preferable to perform natural drying. The film thickness of the obtained fluororesin coating varies depending on the liquid film forming means, but is basically determined by the type of solvent and the amount of the fluororesin dissolved. For example, when a solution in which 0.3 g of Freon 113 is dissolved in 100 g is used, a film of about 0.2 μm can be obtained by the dipping method.

The coating film thus obtained is a film having excellent adhesion to the base material, and provides a transparent surface having various physical properties such as lubricating performance and water / oil repellency.

As described above, examples of using the fluororesin obtained by the method of Japanese Patent Application No. 61-285962 proposed by the present inventors have been described, but the fluororesin low molecular weight product obtained by such a method is not necessarily used. However, it is also possible to use other means, for example, a commercially available low molecular weight fluororesin organic solvent dispersion. That is, "Vydax AR" (tetrafluoroethylene telomer dispersed in Freon 113) manufactured by DuPont is used to remove non-dissolved components by means such as centrifugal sedimentation or filtration, and a fluorocarbon resin low molecular weight Freon 113 solution is obtained. Obtainable. This product can be used as it is in the second method of the coating method of the present invention, and a fluororesin coating film can be formed by forming a liquid film on various substrates and drying it. Also,
The solvent (Freon 113) of the fluorocarbon low molecular weight Freon 113 solution can be volatilized to obtain a solid fluororesin. This has an average molecular weight of 70
It is about 0 and can be used as a target material in the vacuum plating method which is the first method of the coating method of the present invention.

Hereinafter, the present invention will be specifically described with reference to examples.

Reference Example 1 A low molecular weight fluorine-containing resin fine powder was obtained in the same manner as in Japanese Patent Application No. 61-285962. That is, 5 mm square PTFE pellets were charged into a nickel reactor, fluorine gas diluted with nitrogen gas was introduced, and the reaction was carried out at 450 ° C. to cut the main chain of PTFE. The wax thus obtained was roughly pulverized and then finely pulverized with a jet mill to obtain a powder having a melting point of 315 ° C., a molecular weight of 8500 and an average particle diameter of 3 μm. This coarsely pulverized wax was reacted at 550 ° C. in fluorine gas diluted with nitrogen to 10%, and the reaction product gas was sucked and cooled to about 30 ° C. by a cooler to deposit and collect low molecular weight substances. A powder having an average molecular weight of 2000 (Comparative Example 1) thus obtained was obtained. Using this powder, the average molecular weight is about 700, with various evaporation and cooling temperatures.
Three kinds of fluorine-containing resin powders 1000 and 1500 were obtained.

The molecular weight was determined from the relationship between the known melting point of perfluorocarbon and the melting point and molecular weight shown in US Pat. No. 3,067,262.

Example 1 A magnetic disk (aluminum substrate)% substrate having a coated surface of γ-Fe ₂ O ₃ as magnetic powder was used, and the fluorine-containing resin having an average molecular weight of 700 obtained in Reference Example 1 was used as an evaporation source and heated to 150 ° C. ,
Vapor deposition was performed in a vacuum vapor deposition apparatus maintained at a vacuum degree of 3 × 10 ⁻⁴ torr. The vapor deposition time is 3 seconds, and the distance between the vapor deposition source and the substrate is 15 cm. The temperature of the substrate was 30 ° C. at the end of vapor deposition. The obtained film was evaluated. The contact angle was measured by a projection method after dropping one drop of n-exadecane. Friction coefficient is α-alumina slider 20 m circumferential speed
/ Sec, the load was 20 g. The durability was measured by the number of times of sliding until the film was damaged and the magnetic layer surface was scratched. The results are shown in Table 1.

Examples 2 to 4 Vapor deposition was performed in the same manner as in Example 1, except that the type of substrate, the type of fluororesin and the reaction conditions were as shown in Table 1. The results are shown in Table 1.

Example 5 "Vydax AR" manufactured by DuPont was subjected to a centrifugal sedimentation machine to obtain a solution containing no solid content. This solution was heated to volatilize the freon 113 as a solvent to obtain a white solid. This product was confirmed to have a melting point of 82 ° C by DTA analysis,
The average molecular weight was about 700 as in the reference example. This solid content was vapor-deposited in the same manner as in Example 1. The results are shown in Table 1.

Examples 6, 7 and 8 Various fluorine-containing resins obtained in Reference Example 1 (average molecular weight 700)
The fluororesin (Example 7) obtained in (Example 6) and Example 5 was dissolved in Freon 113 to obtain a solution.
3 g / Freon 113-100 g concentration). This solution was spin-coated on the same substrate as in Example 1 and naturally dried to obtain a film. In addition, a solution containing no solid content (Example 8) obtained by centrifugal sedimentation in Example 5 was used as it was, and a film was similarly obtained. The evaluation of this film is shown below.

Film thickness Contact angle Friction coefficient Durability Example 6 0.03μ 81 ° 0.23 29000 Example 7 0.03 80 0.25 30000 Example 8 0.51 75 0.35 10000 Comparative Example 1 Using the fluorine-containing resin having an average molecular weight of 2000 obtained in Reference Example 1, Vapor deposition was carried out in the same manner as in Example 1, but no film was obtained and powder was deposited. The same was true at 70 ° C. Therefore, vapor deposition was performed at a substrate temperature of 100 ° C. The results are shown in Table 1.

[Effects of the Invention] The fluororesin coating of the present invention is coated with a low molecular weight substance in a specific range, and has various physical properties, in particular, its lubricating performance is excellent. Since it does not require a step below, it exhibits an excellent effect for surface modification of a material having no heat resistance or a material which is susceptible to deterioration due to heat history.

Claims (3)

[Claims] 1. A fluorine-containing resin is heated and reacted on a substrate in the presence of a fluorinating agent, and a lower-molecular-weight fluorine-containing resin contained therein is cooled and precipitated from the generated reaction product gas. The average molecular weight obtained by the method is 600-1
A fluororesin-coated body obtained by coating a fluororesin in the range of 500. 2. Obtained by a method of heating and reacting a fluororesin in the presence of a fluorinating agent, and cooling and precipitating a lower molecular weight fluororesin contained therein from the generated reaction product gas. A method for producing a fluororesin-coated body, which comprises coating the fluororesin on a substrate by vacuum plating using a fluororesin having an average molecular weight in the range of 600 to 1500 as a target material. 3. A method in which a fluororesin is heated and reacted in the presence of a fluorinating agent, and a lower molecular weight fluororesin contained therein is cooled and precipitated from the generated reaction product gas. The average molecular weight is 600 ~ 1500 to form a coating film on a substrate by a solution of a fluororesin dissolved in an organic solvent, the production of a fluororesin coating characterized by volatilizing the organic solvent Law.