JP2008133952A - Office automation equipment roll coated with fluorine-based polymer powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an office automation equipment roll coated with fluorine-based polymer powder, whose coat having a nature of improved heat resistance, non-adhesiveness, low friction property and chemical resistance is obtained by electrostatic coating while achieving high coating efficiency. <P>SOLUTION: Fluorinating agent is put in contact with the fluorine-based polymer powder so that the total number of -CH<SB>2</SB>OH and -COF terminal groups is 7-50 per carbon number 10<SP>6</SP>. Then, the fluorine-based polymer powder is put in contact with ammonia gas to convert -COF into -CONH<SB>2</SB>so that the total number of -CH<SB>2</SB>OH and -CONH<SB>2</SB>terminal groups is 7-50 per carbon number 10<SP>6</SP>. Thereby, the office automation equipment roll is manufactured which is coated with the fluorine-based polymer powder having average particle sizes of 5-100 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a roll for office automation equipment coated with a fluoropolymer powder.

  Films formed from fluoropolymers have excellent properties such as heat resistance, wear resistance, non-adhesiveness, low friction, chemical resistance, and electrical insulation, especially heat-melting fluorine-based polymers Polymers are used as powder coatings in various applications such as cookers such as rice cookers and frying pans, rolls for OA equipment, piping and tanks for chemical plants.

However, a small amount of -COF group may be generated at the terminal of the fluoropolymer due to the polymerization mechanism. In addition, in the emulsion polymerization using a polymerization initiator such as ammonium persulfate, a —COOH group is generated, or when methanol is used as a molecular weight regulator, a group such as —COOH, —COOCH ₃ , —CH ₂ OH is generated at the terminal. Such end groups are thermally unstable and thus cause foaming during processing and generation of fluoric acid, and also deteriorate the excellent properties of the fluorine-based polymer film as described above. Therefore, a method is known in which a fluorinating agent such as fluorine gas is brought into contact with the fluoropolymer to convert unstable terminal groups to —CF ₃ (Japanese Patent Publication No. 8-30097).

By the way, in many cases, the powder coating is applied to an object by electrostatic coating. In the most common electrostatic powder coating by the corona charging method, a negative high voltage is first applied to the tip of the spray gun, and the surrounding air is negatively ionized. The powder particles sent together with air from the powder supply device are negatively charged when passing through the tip of the spray gun, and adhere to the grounded object by electrostatic attraction. At this time, almost all the unstable end groups because hardly negatively charged by fluorine-based polymer converted to -CF _3, there is a problem that is very low coating efficiency.

  An object of the present invention is to achieve high coating efficiency in electrostatic coating and to obtain a fluoropolymer powder having properties such as excellent heat resistance, non-adhesiveness, low friction and chemical resistance. It is to provide a roll for coated office automation equipment.

In order to achieve the above object, the present invention is such that the fluorinated polymer powder is contacted with a fluorinating agent so that the total number of —CH ₂ OH and —COF end groups is 7 to 50 per 10 ⁶ carbon atoms. Subsequently, the fluoropolymer powder is brought into contact with ammonia gas to convert —COF into —CONH ₂ , and the total number of —CH ₂ OH and —CONH ₂ end groups is ⁷ to 50 per 10 ⁶ carbon atoms. A roll for office automation equipment coated with a fluoropolymer powder having an average particle diameter in the range of 5 to 100 μm produced by

  Hereinafter, the fluoropolymer powder used in the present invention will be specifically described.

<Fluoropolymer>
In the present invention, the fluoropolymer includes tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer. Examples include coalesced and polyvinylidene fluoride. Of these, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is preferable in terms of excellent heat resistance.

(A) Conversion of unstable terminal groups -COOH, -COOCH ₃ and -CH ₂ OH, which are unstable terminal groups of the fluoropolymer powder, are converted to -COF when contacted with a fluorinating agent, and finally- the CF _3. In the present invention, contact with the fluorinating agent is stopped when the total number of —CH ₂ OH and —COF end groups reaches 7 to 50 per 10 ⁶ carbon atoms by this conversion. As the fluorinating agent, fluorine gas is most preferably used from the viewpoints of having no metal impurities and high fluorination efficiency, but other known fluorinating agents can also be used.

The fluoropolymer powder thus obtained may be used as it is, the -COF by further contact with ammonia gas by converted to -CONH _2, it is possible to obtain a more stable fluoropolymer powder. In this case, all —COF is converted to —CONH ₂ , and the total number of —CH ₂ OH and —CONH ₂ end groups is ⁷ to 50 per 10 ⁶ carbon atoms. The fluoropolymer powder thus obtained can contain fluorine ions in the form of ammonium fluoride.

  Specifically, in the first stage fluorination treatment, PFA is contacted with fluorine gas at a temperature of usually 150 to 250 ° C., preferably 200 ° C., for 1 to 10 hours, preferably 2 to 5 hours. Do. The pressure may be in the range of 1 to 10 atmospheres, and atmospheric pressure is usually employed. The fluorinating agent used may be pure fluorine gas, but from the viewpoint of safety, diluted fluorine gas obtained by diluting fluorine gas with an inert gas to 5 to 25% by volume, preferably 7 to 15% by volume is preferable. Examples of the inert gas include nitrogen gas, argon gas, and helium gas.

In the amidation process of the second stage, the PFA obtained in the first step is contacted with ammonia gas to convert the -COF into -CONH _2. Before passing ammonia gas, it is preferable to wash the PFA with an inert gas such as nitrogen gas. The ammonia gas to be contacted may be pure (100%) or diluted with an inert gas to about 5 to 50% by volume. The treatment time is not particularly limited, but is usually 0.5 to 5 hours, preferably 60 to 90 minutes. The temperature and pressure are not particularly limited, and are usually 0 to 100 ° C., preferably near room temperature (10 to 30 ° C.), and usually 0.5 to 10 atm, preferably atmospheric pressure.

  Such a fluorination treatment may be performed at any stage in the production process described in (B) below.

  In addition, the measurement of the number of each terminal group is demonstrated in the following Example.

Further, the fluoropolymer powder is contacted with a fluorinating agent until the total number of —CH ₂ OH and —COF end groups is 25 or less per 10 ⁶ carbon atoms, and then contacted with ammonia gas to form —COF. -CONH ₂ is converted, and the total number of -CH ₂ OH and -CONH ₂ end groups is 25 or less per 10 ⁶ carbon atoms and fluorinated polymer powder not subjected to fluorination treatment are mixed. Accordingly, the total number of terminal groups such as —COOH, —COOCH ₃ , —CH ₂ OH, —COF, and —CONH ₂ may be 50 or less per 10 ⁶ carbon atoms.

  However, in this case, in the production process described in (B), it is necessary to mix the fluoropolymer powder before compressing it into a sheet. When a fluorinated product and a non-fluorinated product are mixed after forming into a sheet, fluorinated particles and non-fluorinated particles are separately generated, which is not preferable.

(B) Production of fluoropolymer powder The fluoropolymer powder of the present invention has a specific gravity of 90% or more of the true specific gravity (specific gravity of the melt-molded product) using a roll of the fluoropolymer powder. After densification and pulverization under the obtained conditions, fine particles and fibrous particles in the range of 3 to 40% by weight of the entire particle size distribution of the pulverized product are removed by airflow classification, and further, 1 It is desirable to produce by a method that removes ~ 20 wt% coarse particles. Further, it is more desirable to heat-treat at or above the melting start temperature of the fluoropolymer powder after classification of the coarse particles.

  First, the raw material of the fluoropolymer is compressed into a sheet using a roll or the like under a condition that 90% or more, preferably 95 to 99% of the true specific gravity is obtained. When the specific gravity after compression is less than 90% of the true specific gravity, the apparent density of the particles obtained after pulverization is low and the fluidity of the powder is poor. When the specific gravity after compression exceeds 99% of the true specific gravity, the particles obtained after pulverization have a non-uniform shape, and the apparent density is low and the fluidity of the powder becomes poor.

  In forming a sheet with a roll, the sheet thickness is set to 0.05 to 5 mm, preferably 0.1 to 3 mm. The roll to be used is preferably one in which two or more rolls are arranged in a vertical type, an inverted L type, a Z type, and the like, and specifically includes a calendar roll, a mixing roll, a roller compactor, and the like. When such a roll is used, a strong shearing force is applied to the fluoropolymer bulk powder during sheeting, and pores and bubbles present in the bulk powder can be removed to obtain a uniform sheet. It becomes. It is preferable that the sheet is produced under the condition of milky white or transparent at a temperature of 0 to 250 ° C., preferably 5 to 150 ° C.

  In general, the sheet is pulverized by a pulverizer after pulverizing so that the average particle diameter becomes 0.1 to 10 mm by a pulverizer.

  As the crusher, the screen or mesh having a hole having a size of the crushing particle diameter is fixed and crushed, or the crushing machine is crushed by passing several stages of uneven rolls having grooves or undulations, The average particle size is preferably 0.1 to 10 mm.

  The pulverization is generally performed by a mechanical pulverizer. The mechanical pulverizer includes an impact type such as a cutter mill, a hammer mill, a pin mill, and a jet mill, and a grinding type in which the rotary blade and the outer peripheral stator are pulverized by a shearing force caused by unevenness. As the pulverizer, a high shearing method is preferable from the viewpoint of pulverization efficiency. The grinding temperature is -200 to 100 ° C. In the freeze pulverization, it is usually −200 to −100 ° C., but may be pulverized at room temperature (10 to 30 ° C.). Liquid nitrogen is generally used for freeze pulverization, but the equipment is enormous and the pulverization cost is high. It is appropriate to grind at room temperature (10 ° C.) to 100 ° C., preferably at a temperature close to room temperature (10 ° C. to 30 ° C.) in that the process becomes simple and the grinding cost can be suppressed. The obtained powder particles have a uniform particle size distribution rather than a non-uniform form obtained by pulverizing fine particle aggregates or pellets, and the average particle size is 5 to 100 μm.

  After removing fine particles and fibrous particles by airflow classification, coarse particles are further removed by classification.

  In the airflow classification, the pulverized particles are sent to a cylindrical classification chamber by reduced-pressure air, dispersed by a swirling airflow in the room, and fine particles are classified by centrifugal force. The fine particles are collected from the center to a cyclone and a bag filter and formed into a sheet again. In the classification chamber, a rotating body such as a conical cone or a rotor is installed so that the pulverized particles and the air can perform a swirl motion uniformly.

  When using a classification cone, the classification point is adjusted by adjusting the air volume of the secondary air and the gap between the classification cones. When using a rotor, adjust the air volume in the classification chamber according to the number of rotations of the rotor. The wind pressure of the blower is 0.1 to 1 MPa, preferably 0.3 to 0.6 MPa. The classification range is 3 to 40% by weight, preferably 5 to 30% by weight, and 3 to 40% by weight of fine particles and fibrous particles are removed. When the fine particles to be removed are less than 3% by weight, the fluidity of the powder cannot be improved, and the leveling property of the coating film is inferior because the particle size distribution is extremely wide. On the other hand, if the fine particles to be removed exceed 40% by weight, it is not suitable in terms of cost.

  Examples of the method for removing coarse particles include airflow classification using a mesh or vibrating sieve, but the former is preferable. The classification range depending on the particle size is 1 to 20% by weight, preferably 2 to 10% by weight of the entire particle size distribution of the pulverized product, and coarse particles in this range are removed.

  Fine particles and fibrous particles recovered in the airflow classification can be formed into a sheet again in the same manner as the raw powder. Moreover, the coarse particles classified by the airflow classification using a mesh or the vibrating sieve can be returned to the pulverizer and recycled.

  When the classified powder is momentarily brought into contact with an air flow above the melting start temperature of the fluoropolymer powder using a continuous air flow type heat dryer, the powder particle surface becomes rounded, the apparent density and powder The fluidity of the coating can be further improved, and a preferable coating powder can be obtained.

  The contact temperature of continuous air flow type heat drying is 1000 ° C. or less, preferably 200 to 800 ° C., and the contact time is 0.1 to 10 seconds. As the heat source, gas heating is preferable in terms of energy saving. The heat-treated powder can be further removed by classifying coarse particles by an air flow type sieve or a vibrating sieve to obtain a powder having a narrow particle size distribution.

  The powder thus obtained can be coated with an ultrathin film having a thickness of 5 to 30 μm. In order to obtain an ultra-thin film having excellent leveling properties, it is required that the powder has a well-shaped shape, that the apparent density is high, that the powder has excellent fluidity, and that it is easily meltable. The average particle size of the powder is 5 to 30 μm, preferably 10 to 25 μm. When the above conditions are not satisfied, pinholes may be generated in the film, or the surface may become bruised.

  In order to obtain a thin film having a thickness of 30 to 100 μm, heat treatment is not necessarily required. The powder for coating has a uniform powder shape, and the average particle size is 5 to 100 μm, preferably 30 to 60 μm.

  Examples of the powder coating method include spraying, electrostatic spraying, fluid immersion, electrostatic fluid immersion, and the like. It can also be used as a water-dispersed paint or organic solvent-dispersed paint.

As already described, in order to improve the heat resistance, non-adhesiveness, low frictional properties, chemical resistance, and other properties of the film formed from the fluoropolymer, the non-fluorescence of the fluoropolymer powder. method for converting stable end groups to -CF ₃ has been known. However, the fluoropolymer powder in which almost all unstable terminal groups have been converted is difficult to be negatively charged and therefore cannot adhere to the object to be coated, and the coating efficiency is extremely low. On the other hand, since the fluorine-based polymer powder which leaves such a small amount of end groups easily retains a negative charge, it can achieve high coating efficiency, and the resulting film is also made of a fluorine-based polymer. It is possible to sufficiently exhibit excellent properties.

Specifically, when the total number of unstable terminal groups of the fluoropolymer powder is 6 or less per 10 ⁶ carbon atoms, the coating efficiency is significantly reduced. On the other hand, when the total number of unstable terminal groups of the fluoropolymer powder exceeds 50 per 10 ⁶ carbon atoms, the non-adhesiveness of the coating is lowered.

  As shown in (A) above, when the fluorinated particles and non-fluorinated particles are produced separately, the non-fluorinated particles are selectively applied to the object to be coated. The coating efficiency is low because it is applied, and therefore the properties of the resulting film are not very good.

  As for the production of the fluoropolymer powder, a method of obtaining an emulsion polymerization dispersion by a so-called spray drying method (Japanese Patent Publication No. 53-11296) may be used. However, the pulverization method as shown in (B) above is preferred. Is desirable. The electric charge existing near the tip of the spray gun reaches the powder particles along the electric force lines, but the electric force lines are difficult to reach because the powder obtained by the spray drying method is spherical. On the other hand, the powder obtained by the pulverization method is non-spherical and has at least one point. Since the lines of electric force easily reach such a pointed portion, the powder obtained by the pulverization method can sufficiently retain electric charges, and can achieve high coating efficiency.

  Examples of the use of the fluoropolymer powder for electrostatic coating of the present invention include household appliances such as kitchen appliances, applications that require weather resistance, such as metal plates for construction, rolls for copying machines and printers. Applications that require heat resistance and non-adhesiveness such as industrial rolls and hoppers, and applications that require chemical resistance such as piping and tanks in chemical plants.

Hereinafter, the present invention will be specifically described with reference to examples.
In the following examples and comparative examples, various physical properties were measured as follows.

Average Particle Size The average particle size of various powders was measured with a laser diffraction / scattering particle size distribution analyzer SALD-1100 manufactured by Shimadzu Corporation using isopropyl alcohol as a dispersion.

Analysis of terminal groups Fluoropolymer powder was compression molded at 350 ° C. for 30 minutes to form a film having a thickness of 0.25 to 0.3 mm. The infrared absorption spectrum of this film was analyzed, the type was determined by comparison with the infrared absorption spectrum of a known film, and the number was calculated from the difference spectrum by the following formula.
Number of end groups (per 10 ⁶ carbon atoms) = I x K / t
(Here, I is absorbance, K is a correction factor, and t is film thickness (mm).)

The correction factors for the target end groups are as follows. This correction coefficient is determined from the infrared absorption spectrum of the model compound in order to calculate the terminal group per 10 ⁶ carbon atoms.

  Infrared absorption spectra were analyzed in 100 scans using a Perkin-Elmer Perkin-Elmer FTIR spectrometer 1760X and a Perkin-Elmer 7700 professional computer.

Coating efficiency Using an electrostatic powder coating apparatus Integral 2007A manufactured by Nippon Wagner Spray Tech Co., Ltd., a fluoropolymer powder was coated on a 10 cm square aluminum plate for 3 seconds. The coating weight can be calculated from the difference between the total weight of the aluminum plate after painting and the weight of the aluminum plate before painting. Further, using the above electrostatic powder coating apparatus, the fluorine-based polymer powder was discharged into a polyethylene bag for 3 seconds. The discharge weight can be calculated from the difference between the total weight of the polyethylene bag after discharge and the weight of the polyethylene bag before discharge. The coating efficiency was determined by “coating efficiency = coating weight / discharge weight”.

Release of rice from rice cooker Sandblasting was applied to the inner pot for RCK-X18Z rice cooker made by Toshiba Corporation, and EK-1909BKN (manufactured by Daikin Industries, Ltd. Main components: polytetrafluoroethylene and polyamideimide) After coating and drying, a fluoropolymer powder was applied and baked at 380 ° C. for 20 minutes. This inner pot was used for the above-mentioned rice cooker, and a single rice was cooked in the normal mode. Within 30 seconds after cooking, the inner pot was taken out and turned upside down and dropped from a height of 5 cm. At this time, a state where almost no rice remained as shown in Photo 1 in FIG. 1 was evaluated as ◯, a state where some rice remained as shown in Photo 2, and a state where much rice remained as shown in Photo 3 was evaluated as X. .

Example 1
According to the method described in JP-A No. 58-189210, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) (tetrafluoroethylene to perfluoroalkyl vinyl ether weight ratio = 97: 3) by an aqueous suspension polymerization method. Manufactured. This is designated as polymer bulk powder A (apparent specific gravity 0.65, true specific gravity 2.15, average particle size 350 μm).

  Polymer bulk powder A was compressed into a sheet having a width of 60 mm and a thickness of 5 mm using a roller compactor BCS-25 type manufactured by Shinto Kogyo Co., Ltd. to obtain a polymer sheet. The specific gravity of the sheet was 2.1. The polymer sheet was crushed to a diameter of about 2 mm with a crusher attached to the roller compactor to obtain a polymer crushed product B.

A fluorinated polymer crushed product C was obtained by contacting the polymer crushed product B with fluorine gas at 200 ° C. for 4 hours for fluorination treatment. Fluorine gas was used after being diluted to 20% by volume with nitrogen gas from the viewpoint of safety, and the pressure of this mixed fluorine gas was 1 kgf / cm ² .

Ammonia gas was brought into contact with the fluorinated polymer crushed product C at room temperature for 1 hour to obtain an amidated polymer crushed product D. The pressure of this ammonia gas was 1 kgf / cm ² .

  The amidated polymer pulverized product D was pulverized at 11,000 rpm at room temperature using a pulverizer Cosmomizer N-1 manufactured by Nara Machinery Co., Ltd. to obtain a polymer powder E.

  Polymer powder E was classified by a cyclone and a bag filter to remove fine particles and fibrous particles having a low apparent specific gravity using an air classifier Micron Classifier MC100 manufactured by Seishin Enterprise Co., Ltd. The amount removed was 15% by weight. Subsequently, polymer powder F from which coarse particles of 170 mesh (aperture 88 μm) or more were removed was obtained using a classifier Hi-Boulder 300SD type manufactured by Shin Tokyo Machine Co., Ltd. The amount removed was 4% by weight.

  The polymer powder F was subjected to a heat treatment by contacting a gas hot air of 550 ° C. exceeding the melting start temperature of PFA for about 1 second using a 4-inch type continuous air dryer manufactured by Seishin Enterprise Co., Ltd. Powder G was obtained.

  The polymer powder G was evaluated for end groups, coating efficiency, and rice releasability.

Example 2
The end groups, coating efficiency, and rice release properties of the polymer powder E obtained during the procedure of Example 1 were evaluated.

Comparative Example 1
The polymer crushed product B obtained in the middle in Example 1 was pulverized at 11000 rpm at room temperature using a pulverizer Cosmizer N-1 type manufactured by Nara Machinery Co., Ltd. without performing fluorination treatment.

  The pulverized product was classified by a cyclone and a bag filter to remove fine particles and fibrous particles having a low apparent specific gravity using an air classifier Micron Classifier MC100 manufactured by Seishin Enterprise Co., Ltd. Subsequently, coarse particles of 170 mesh (aperture 88 μm) or more were removed using a classifier Hi-Boulder 300SD type manufactured by Shin Tokyo Machine Co., Ltd.

  Next, using a 4-inch type continuous jet dryer manufactured by Seishin Co., Ltd., a hot gas of 550 ° C. exceeding the melting start temperature of PFA was contacted for about 1 second to obtain polymer powder H. .

  The polymer powder H was evaluated for end groups, coating efficiency, and rice releasability.

Comparative Example 2
The polymer crushed product B obtained in the middle in Example 1 was contacted with fluorine gas at 230 ° C. for 5 hours and sufficiently fluorinated, and then contacted with ammonia gas at room temperature for 1 hour to perform amidation. . The fluorine gas used was diluted to 20% by volume with nitrogen gas from the viewpoint of safety, and the pressure of the mixed fluorine gas was 1 kgf / cm ² . The pressure of ammonia gas was 1 kgf / cm ² .

  The amidated polymer pulverized product was pulverized at 11000 rpm at room temperature using a pulverizer Cosmizer N-1 type manufactured by Nara Machinery Co., Ltd. to obtain a polymer powder.

  The polymer powder was classified by a cyclone and a bag filter to remove fine particles and fibrous particles having a low apparent specific gravity using an air classifier Micron Classifier MC100 manufactured by Seishin Enterprise Co., Ltd. Subsequently, coarse particles of 170 mesh (aperture 88 μm) or more were removed using a classifier Hi-Boulder 300SD type manufactured by Shin Tokyo Machine Co., Ltd.

  Next, using a 4-inch type continuous air flow dryer flash jet dryer manufactured by Seishin Co., Ltd., a hot gas of 550 ° C. exceeding the melting start temperature of PFA was brought into contact for about 1 second to obtain polymer powder I. .

  The polymer powder I was evaluated for end groups, coating efficiency, and rice releasability.

Comparative Example 3
The polymer powder H obtained in Comparative Example 1 and the polymer powder I obtained in Comparative Example 2 are blended, and the total number of unstable terminal groups is in the range of 7 to 50 per 10 ⁶ carbon atoms. Got J.

  The end groups and coating efficiency of the polymer powder J were evaluated.

Example 3
A fluorinated polymer bulk K was obtained by contacting the polymer bulk A obtained in Example 1 with a fluorine gas at 200 ° C. for 5 hours for fluorination treatment. When this terminal group was analyzed, the total number of unstable terminal groups was 9 per 10 ⁶ carbon atoms.

Polymer bulk powder A and fluorinated polymer bulk powder K were blended to obtain polymer bulk powder L having a total number of unstable terminal groups in the range of 7 to 50 per 10 ⁶ carbon atoms.

  The polymer bulk L was compressed into a sheet having a width of 60 mm and a thickness of 5 mm using a roller compactor BCS-25 type manufactured by Shinto Kogyo Co., Ltd. to obtain a polymer sheet. The polymer sheet was crushed to a diameter of about 2 mm with a crusher attached to the roller compactor, and pulverized at 11000 rpm at room temperature using a pulverizer Cosmizer N-1 type manufactured by Nara Machinery Co., Ltd.

  The pulverized product was classified by a cyclone and a bag filter to remove fine particles and fibrous particles having a low apparent specific gravity using an air classifier Micron Classifier MC100 manufactured by Seishin Enterprise Co., Ltd. Subsequently, polymer powder M from which coarse particles of 170 mesh (aperture 88 μm) or more were removed was obtained using a classifier Hi-Boulder 300SD type manufactured by Shin Tokyo Machine Co., Ltd.

  The polymer powder M was evaluated for end groups, coating efficiency, and rice release properties.

Example 4
The fluorinated polymer crushed product C obtained in the middle in Example 1 was pulverized to 11000 rpm at room temperature using a pulverizer Cosmizer N-1 type manufactured by Nara Machinery Co., Ltd. to obtain a polymer powder N .

  The polymer powder N was evaluated for end groups, coating efficiency, and rice releasability.

Example 5
The end group, coating efficiency, and rice releasability of the polymer powder F obtained in the middle in Example 1 were evaluated.

Example 6
The polymer powder M obtained in Example 3 was subjected to gas hot air at 550 ° C. exceeding the melting start temperature of PFA for about 1 second using a continuous air dryer flash jet dryer 4 inch h type manufactured by Seishin Enterprise Co., Ltd. The polymer powder O was obtained by contact.

The polymer powder O was evaluated for end groups, coating efficiency, and rice release properties.
The results are shown in Table 2.

FIG. 1 is photographs 1, 2, and 3 showing the standard of releasability of rice from a rice cooker.

Claims (1)

A fluorine-containing polymer powder is brought into contact with a fluorinating agent so that the total number of —CH ₂ OH and —COF end groups is 7 to 50 per 10 ⁶ carbon atoms, and then the fluorine-based polymer powder is treated with ammonia gas. The average particle size produced by converting -COF to -CONH ₂ by contacting with 7 to 50 per 10 ⁶ carbon atoms with the total number of -CH ₂ OH and -CONH ₂ end groups being A roll for office automation equipment coated with a fluoropolymer powder in the range of 5 to 100 μm.

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