CA1306326C - Powders of tetrafluoroethylene copolymer and process for preparing the same - Google Patents
Powders of tetrafluoroethylene copolymer and process for preparing the sameInfo
- Publication number
- CA1306326C CA1306326C CA000554918A CA554918A CA1306326C CA 1306326 C CA1306326 C CA 1306326C CA 000554918 A CA000554918 A CA 000554918A CA 554918 A CA554918 A CA 554918A CA 1306326 C CA1306326 C CA 1306326C
- Authority
- CA
- Canada
- Prior art keywords
- powder
- copolymer
- tetrafluoroethylene
- average particle
- particle size
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B9/00—Making granules
- B29B9/02—Making granules by dividing preformed material
- B29B9/04—Making granules by dividing preformed material in the form of plates or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B9/00—Making granules
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
- C08J3/122—Pulverisation by spraying
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
Abstract
ABSTRACT
Powders of tetrafluoroethylene copolymer having a non-spherical particle shape, a frictional packing ration of 20 to 100 % and an average particle size of 5 to 500 µm, and the tetrafluoroethylene copolymer is a tetrafluoroethylene/
hexafluoropropylene copolymer or a tetrafluoroethylene/
fluoro(vinyl ether) copolymer, and the powders are userful for powder coatings, particularly roto-molding, roto-lining and electrostatic coating, and can provide coatings having a good appearance and no bubble.
Powders of tetrafluoroethylene copolymer having a non-spherical particle shape, a frictional packing ration of 20 to 100 % and an average particle size of 5 to 500 µm, and the tetrafluoroethylene copolymer is a tetrafluoroethylene/
hexafluoropropylene copolymer or a tetrafluoroethylene/
fluoro(vinyl ether) copolymer, and the powders are userful for powder coatings, particularly roto-molding, roto-lining and electrostatic coating, and can provide coatings having a good appearance and no bubble.
Description
32~
POWDERS OF TETRAFLUOROETHYLENE COPOLYMER
AND PROCESS FOR PREPARING THE SAME
BACKGROUND
The present invention relates to powders of tetrafluoroethylene (TFE) copolymer useful for powder coating, and a process for preparing the same.
Study and development for powders oE TFE
copolymer used for powder coating have proceeded on the basis of the theory that such powders preferably have a spherical particle shape in a viewpoint of flowability ~Japanese Tokkyo Kokai No. 240713/1985).
To roto-molding or roto-lining which has been recently utilized as a method of powder coatings, however, the above theory could not be fully applied.
For instance, there are some problems such that a coating formed on a mold surface partially falls off to yield coating defects on a surface of the molded article, that a coating surface largely undulates and has continuous ball-like projections, and that a coating contains bubbles or cells because its gas content cannot be sufficiently removed.
As a result of the inventor ' intensive study, it has been found out that the above-mentioned problems can be solved by using powders of TFE copolymer having particular powder properties.
SUMMARY OF THE INVENTION
According to the present invention, there can be provided powders of TFE copolymer having a non-spherical particle shape, a frictional packing ratio of 20 to 100 %, and an average particle size of 5 to 500 ~m.
BRIEF EXPLANATION OF THE D~AWING
~ . ~
Fig. 1 is a scanning-type electron microscope photograph (100 magnitudee) of a powder prepared in Preparation Example 4.
~ ` ~
~3~ 2~
`\ -- 2 DETAILED DESCRIPTION
In the present invention, the powders should have a non-spherical particle shape. This property i5 important for obtaining an appropriate friction in the powder coating step, as explained hereinbelow.
Film forming operation of the roto-molding and roto-lining is carried out by externally heating a mold charged with a powder in such an amount to give a desired thickness while rotating the mold biaxially or uniaxially. In the course of the film formation, the powder is heated by contacting with the inner surface of the heated mold, and gradually adheres onto the mold surface to form a molten thin film, from which air present between the powder particles is released by itself. The adhesion and melting of the remaining heated powder is gradually and continuously effected to produce a film having a desired thickness without bubbles or cells. For performing such a good film formation~ it is necessary to contact a powder with a heated mold surface for an appropriate period of time. Namely, when the contacting time is shorter, an adherent powder partially falls of from a mold surface, or on the contrary a powder is wholely and homogeneously heated, and then the homogeneously heated powder wholely adheres onto the mold surface and is melted for a very short time to form a film without releasing bubbles.
Such an appropriate contacting time cannot be obtained by using spherical particles, but can be obtained by using non-spherical particles which have a large friction. The word "non-spherical shape" as used in the specification means a shape having at lea~t a linear profile when a particle is cut along an optional line, even if the remaining profile is round. The sectional profile should not be a smooth circle.
The frictional packing ratio of the powder of the invention defined by the ollowing equation (I) must be within a range from 20 to 100 ~.
~` ~ ~5, ~3~3~i - 3 p Frictional Packing Ratio ~) =l 2-1) x 100 (I) wherein Pl: bulk density of powder measured according to JIS K 6891 P2: bulk density of packed powder measured aecording to JIS K 6891. Packing operation is as follows: a 100 m~ SUS container (diameter: 40 mm, height: 79.6 mm) is charged with a powder, and the container is vibrated by touching a vibrator IPanabrator EV234 available from Matsushita Electric Industrial Co., Ltd.) on a central side portion of the container for one minùte~ This vibration operation is repeated by adding a powder to the container until the reducing volume b~comes lower than 5 ~ by volume of the container.
Finally the container is filled with an addi-tional powder, and then the bulk density of the packed powder is measured.
This frictional packing ratio shows the degrees of both friction and packing density of the powder. A small value means a low friction of a powder, and a large value means a high friction of a powder.
A frictional packing ratio of the powder according to the invention is 20 to 100 ~. When the ratio is less than 20 ~, the above-mentioned problems cannot be solved due to its low friction. A TFE
copolymer powder having a spherical shape generally has a frictional packing ratio of 5 to 15 ~. When more than 100 ~, a uniform coating cannot be obtained due to its high friction.
An average particle size of the powder according to the invention is 5 to 500 ~m. In case of a powder for roto-molding and roto-lining, the powder preferably has an average particle size of 100 to 150 ~m, and in case for electrostatic powder coating the powder preferably ha~ an average particle size of 5 to 150 ~m.
Average particle sizes of powder~ are measured ~ 7 ~' - 130~3~
" -- 4 accolding to ASTM D-1457-69. Sieves of 16 to 400 mesh are provided on the basis of wet sieve method. Among them, by using five sieves 50 that a sieve having a pore opening size almost the same as an expected average particle size of a powder to be measured is a central sieve, the powder is sieved. The average particle size is determined by using a logarithm probability paper described in the ASTM on the basis of relationship be-tween the cumulative residual percentage and pore opening size of the sieve. A powder having an average particle size of not more than 400 mesh (not more than 33 um) is measured as follows: a beaker of 100 mQ is charged with 50 m~ of Daifloil S-519 (chlorotrifluoroethylene telomer oil available from Daikin Industries, Ltd.), and 0.1 g of a powder to be measured is added thereto. After dispersing the powder with a supersonic dispersing apparatus for one minute, a sample is introduced to a spectral cell, and then the average particle size is measured by centrifugal transmittance method with CAPA-500 manufactured by HORIBA, LTD.
Particle size distribution as well as particleshape influences the packing density of powder. For instance, when a particIe size distribution is wide, the amount of air between particles can be reduced because the packing state becomes near closest packing. However, even in such a case, it is necessary to regulate the frictional packing ratio within the above-mentioned range.
The powder having a preferable flowability satisfies the following equation (II):
log ~ ~ 2.45 P1 ~ 0.75 wherein ~: average particle size Pl: bulk density as defined in the equation (I).
The TFE copolymer used in the invention is a TFE/hexafluoropropylene copolymer or a TFE/fluoro(vinyl ether) copolymer. ~ach of the copolymers preferably .
~3~63~
contains TFE unit in an amount o~ 85 to 99.5 % by mole.
Preferred fluoro(vinyl ether) is a compound of the formula:
CF2 = CF(OCF2CF(CF3))mO(CF2)nCF2X
wherein x is hydrogen atom or fluorine atom, m is 0 or an integer of 1 to 4, n is 0 or an integer of 1 to 7.
Examples of the fluoro(vinyl ether) are, for instance, perfluoro(methyl vinyl ether), pe~fluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), CF2 = CFOCF2CF(CF3)OCF2CF3, CF2 = CFOCF2cF(cF3)O(c~2)2cF3 CF2 = CFOCF2CF(CF3)O(CF2)3CF3 CF2 = CF(0cF2cF(cF3))2ocF2~F
CF2 = CF(OCF2cF(cF3))2O(cF2)2cF3~
POWDERS OF TETRAFLUOROETHYLENE COPOLYMER
AND PROCESS FOR PREPARING THE SAME
BACKGROUND
The present invention relates to powders of tetrafluoroethylene (TFE) copolymer useful for powder coating, and a process for preparing the same.
Study and development for powders oE TFE
copolymer used for powder coating have proceeded on the basis of the theory that such powders preferably have a spherical particle shape in a viewpoint of flowability ~Japanese Tokkyo Kokai No. 240713/1985).
To roto-molding or roto-lining which has been recently utilized as a method of powder coatings, however, the above theory could not be fully applied.
For instance, there are some problems such that a coating formed on a mold surface partially falls off to yield coating defects on a surface of the molded article, that a coating surface largely undulates and has continuous ball-like projections, and that a coating contains bubbles or cells because its gas content cannot be sufficiently removed.
As a result of the inventor ' intensive study, it has been found out that the above-mentioned problems can be solved by using powders of TFE copolymer having particular powder properties.
SUMMARY OF THE INVENTION
According to the present invention, there can be provided powders of TFE copolymer having a non-spherical particle shape, a frictional packing ratio of 20 to 100 %, and an average particle size of 5 to 500 ~m.
BRIEF EXPLANATION OF THE D~AWING
~ . ~
Fig. 1 is a scanning-type electron microscope photograph (100 magnitudee) of a powder prepared in Preparation Example 4.
~ ` ~
~3~ 2~
`\ -- 2 DETAILED DESCRIPTION
In the present invention, the powders should have a non-spherical particle shape. This property i5 important for obtaining an appropriate friction in the powder coating step, as explained hereinbelow.
Film forming operation of the roto-molding and roto-lining is carried out by externally heating a mold charged with a powder in such an amount to give a desired thickness while rotating the mold biaxially or uniaxially. In the course of the film formation, the powder is heated by contacting with the inner surface of the heated mold, and gradually adheres onto the mold surface to form a molten thin film, from which air present between the powder particles is released by itself. The adhesion and melting of the remaining heated powder is gradually and continuously effected to produce a film having a desired thickness without bubbles or cells. For performing such a good film formation~ it is necessary to contact a powder with a heated mold surface for an appropriate period of time. Namely, when the contacting time is shorter, an adherent powder partially falls of from a mold surface, or on the contrary a powder is wholely and homogeneously heated, and then the homogeneously heated powder wholely adheres onto the mold surface and is melted for a very short time to form a film without releasing bubbles.
Such an appropriate contacting time cannot be obtained by using spherical particles, but can be obtained by using non-spherical particles which have a large friction. The word "non-spherical shape" as used in the specification means a shape having at lea~t a linear profile when a particle is cut along an optional line, even if the remaining profile is round. The sectional profile should not be a smooth circle.
The frictional packing ratio of the powder of the invention defined by the ollowing equation (I) must be within a range from 20 to 100 ~.
~` ~ ~5, ~3~3~i - 3 p Frictional Packing Ratio ~) =l 2-1) x 100 (I) wherein Pl: bulk density of powder measured according to JIS K 6891 P2: bulk density of packed powder measured aecording to JIS K 6891. Packing operation is as follows: a 100 m~ SUS container (diameter: 40 mm, height: 79.6 mm) is charged with a powder, and the container is vibrated by touching a vibrator IPanabrator EV234 available from Matsushita Electric Industrial Co., Ltd.) on a central side portion of the container for one minùte~ This vibration operation is repeated by adding a powder to the container until the reducing volume b~comes lower than 5 ~ by volume of the container.
Finally the container is filled with an addi-tional powder, and then the bulk density of the packed powder is measured.
This frictional packing ratio shows the degrees of both friction and packing density of the powder. A small value means a low friction of a powder, and a large value means a high friction of a powder.
A frictional packing ratio of the powder according to the invention is 20 to 100 ~. When the ratio is less than 20 ~, the above-mentioned problems cannot be solved due to its low friction. A TFE
copolymer powder having a spherical shape generally has a frictional packing ratio of 5 to 15 ~. When more than 100 ~, a uniform coating cannot be obtained due to its high friction.
An average particle size of the powder according to the invention is 5 to 500 ~m. In case of a powder for roto-molding and roto-lining, the powder preferably has an average particle size of 100 to 150 ~m, and in case for electrostatic powder coating the powder preferably ha~ an average particle size of 5 to 150 ~m.
Average particle sizes of powder~ are measured ~ 7 ~' - 130~3~
" -- 4 accolding to ASTM D-1457-69. Sieves of 16 to 400 mesh are provided on the basis of wet sieve method. Among them, by using five sieves 50 that a sieve having a pore opening size almost the same as an expected average particle size of a powder to be measured is a central sieve, the powder is sieved. The average particle size is determined by using a logarithm probability paper described in the ASTM on the basis of relationship be-tween the cumulative residual percentage and pore opening size of the sieve. A powder having an average particle size of not more than 400 mesh (not more than 33 um) is measured as follows: a beaker of 100 mQ is charged with 50 m~ of Daifloil S-519 (chlorotrifluoroethylene telomer oil available from Daikin Industries, Ltd.), and 0.1 g of a powder to be measured is added thereto. After dispersing the powder with a supersonic dispersing apparatus for one minute, a sample is introduced to a spectral cell, and then the average particle size is measured by centrifugal transmittance method with CAPA-500 manufactured by HORIBA, LTD.
Particle size distribution as well as particleshape influences the packing density of powder. For instance, when a particIe size distribution is wide, the amount of air between particles can be reduced because the packing state becomes near closest packing. However, even in such a case, it is necessary to regulate the frictional packing ratio within the above-mentioned range.
The powder having a preferable flowability satisfies the following equation (II):
log ~ ~ 2.45 P1 ~ 0.75 wherein ~: average particle size Pl: bulk density as defined in the equation (I).
The TFE copolymer used in the invention is a TFE/hexafluoropropylene copolymer or a TFE/fluoro(vinyl ether) copolymer. ~ach of the copolymers preferably .
~3~63~
contains TFE unit in an amount o~ 85 to 99.5 % by mole.
Preferred fluoro(vinyl ether) is a compound of the formula:
CF2 = CF(OCF2CF(CF3))mO(CF2)nCF2X
wherein x is hydrogen atom or fluorine atom, m is 0 or an integer of 1 to 4, n is 0 or an integer of 1 to 7.
Examples of the fluoro(vinyl ether) are, for instance, perfluoro(methyl vinyl ether), pe~fluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), CF2 = CFOCF2CF(CF3)OCF2CF3, CF2 = CFOCF2cF(cF3)O(c~2)2cF3 CF2 = CFOCF2CF(CF3)O(CF2)3CF3 CF2 = CF(0cF2cF(cF3))2ocF2~F
CF2 = CF(OCF2cF(cF3))2O(cF2)2cF3~
2 CF(ocF2cF(cF3))2o(cF2)3c~3r or the like.
A TFE/fluoro(vinyl ether) copolymer can be prepared, for example, by dispersion polymerization described in Japanese Tokkyo Kokai No. 189210/19~3~ or by emulsion polymerization described in Japanese Tokkyo Kokoku No.
20788/1983.
The powder of the present inventioll can be prepared by producing a sheet with rolls from a TFE
copolymer raw powder, and then pulverizing the sheet.
As the raw powder of TFE copolymer used in the process of the invention, there may be employed a dry powder prepared by dispersion polymerization described in Japanese Tokkyo ~okai No~ 189210/1983 or prepared by emulsion polymerization described in Japanese Tokkyo Kokoku No. 20788/1973. Since a dry powder prepared by emulsion polymerization contains an emulsifier or a coagulant, a dry powder prepared by dispersion polymerization is preferred in view of contaminant.
Production of a sheet with rolls is operative so that a sheet has a thickness of 0.05 to 5 mm, preferablly 0.1 to 3 mm.
The roll used in the present invention preferably comprises -two or more rolls which are ~A
-1.3~ i3,. ~
arranged in perpendicular, inverted L, or Z position.
Example~ are, for instance, a calender roll, mixing roll or the like. It is preferable to regulate the roll distance, rotation speed, pressure, temperature and the like. According to this method, since a large slide shearing force is applied to the copolymer, bubbles and cells in the copolymer can be released out of the copolymer to give a uniform and homogeneous sheet. The sheet produced by the method is uniform both in the surface and inner regions in comparison with a sheet produced by other press methods as described in U.S.
Patent No. 4,312,961, and can give the powder which satisfies the powder properties of the invention by the subsequent pulverizing step. The main defect of the press method is contamination of the TFE copolymer by a small amount of metal powder which is yielded due to abrasion between the metal molds at the pressing operation.
This contaminated TFE copolymer cannot be used for coat-ings or containers utili~ed in the semiconductor industry because contamination gives serious damages to semiconductors. In addition, since release o bubbles or cells in the raw powder particles requires a very high pressure according to the press method, a special equipment is needed.
As operation conditions for production of sheet, there is preferably employed such conditions that an operation temperature is 0 to 250C, particularly 30 to 200C, and the resulting sheet is transparent or translucent.
The thickness of the sheet is preferably 0.05 to 5 mm. When more than 5 mm a uniform sheet is hard to obtain because the shearing force to the outer surface portion is different from that to the inner portion. A
sheet thinner than 0.05 mm has a problem of productivity. The pulverizing step is carried out by applying impact force, shearing force and compre~sion force to the sheet with machines such a~ a cutter mill, hammer mill or jet mill. Operation temperature is 13~3~
generally -200 to 100C.
Thermal stability o TFE copolymers can be improved by known methods desclosed in Japanese Tokkyo Kokoku No. 23245/1971. Those methods may be employed in the present invention. A preferred thermal stabiliza-tion method to be applied to the invention is fluorine gastreatment, which can be applied eith~r to the copolymer obtained from the sheet production step or the copolymer obtained from the pulverizing step. As conditions of the fluorine gas treatment, there may be employed a fluorine gas concentration of 5 to 30 % by volume lthe other gas being an inert gas such as nitrogen gas), a pressure of 0 to 10 kgf/cm2G, and a reaction temperature of 5~ to 250C.
Thermal stability ratio of a copolymer is calculated according to the equation (III):
Thermal Stability Ratio (%) = (1 ~ ~ a~) x 100 (III) wherein MI(a): melt index of a sample without heat treatment measured at 372C according to MI(b): melt index of an sample which is su~jected to heat treatment at 380C for 5 hours.
The fluorine gas treatment is preferably car-ried out until the thermal stability ratio becomes 20%
or lower.
The TFE copolymer powder of the present invention is suitably used as materials for molded articles such as pipes, parts, lining container or tank utilized ~or production of semiconductors which are ser-iously impaired by contamination. Also the powder can be utilized for usual corrosion resistive lining, roto-molding ~e.g. for containers), roto-lining (e.g. for inner lining of pipes or joints) or the like. Those articles can be produced by various proce~sing methods such as electrostatic powder coating method, fluidized dip coating method, roto-molding method and roto-lining :~3~32~
method.
The pres~nt invention is more specifically described and explained by means oE the following Examples. It is to be understood that the present invention is not limited to the Examples and various changes and modifications may be made in the invention without departing from the spirit and scope thereof.
A dry powder of T~E/perfluoro(propyl vinyl ether) copolymer (98.5/1.5 molar ratio) was prepared according to the dispersion polymerization described in Japanese Tokkyo Kokai No. 189210/1983. From the dry powder (bulk density: 0.57 g/cc, average particle size:
400 to 600 ~m), a translucent sheet having a thickness of 1 mm was produced by using special compression rolls (Roller Compactor "MINI" manufactured by Freund Industries, Co., Ltd.) under the following conditions: a roll rotation speed o~ 10 rpm, a feeder rotation speed of 20 rpm, a compression gauge pressure of 150 kg/cm2G and a roll surface temperature of 50C.
The sheet was pulverized by using an atomizer ~manufactured by Fuji Paudal Co., Ltd.) under the following condition~: a rotation speed of 1300 rpm, and a pore opening size of screen of 1.5 mm.
The resulting powder was sieved with a sieve o~
35 mesh to give a non-spherical TFE copolymer powder having a frictional packing ratio of 35.5 %, a bulk density (Pl) of 0.92 g/cc, an average particle size of 205 ~m, and a thermal stability ratio of 75 %.
A tran~lucent sheet havin~ a thickness of 1 mm was produced according to the same procedures and by usin~ the same TFE copolymer as in Preparation Example 1, and then was pulverized with an atomizer (manufactured by Fu ji Paudal Co., Ltd.) under the following conditions: a rotation speed of 3900 rpm and a pore opening size of * Trade-mark `~.
. " ' . ' ' ~:
.
~3~63~
g screen of 0.5 mm.
The resulting powder was sieved with a sieve of 60 mesh to give a non-spherical TFE copolymer powder having a frictlonal packing ratio of 60.0 %, a bulk density (Pl) of 0.55 g/cc, an average particle size of 40 ~m, and a thermal stability ratio of 72.5 ~.
A dry powder (bulk density: 0.48 g/cc, average particle size: 400 to 800 ~m) of TFE/hexafluoropropylene copolymer (92/8 molar ratio) was prepared by dispersion polymerization. From the dry powder a translucent sheet having a thickness of 1.5 mm was produced by using special compression rolls (Roller Compactor "MINI"
manufactured by Freund Industries, Co., Ltd.~ under the following conditions: a roll rotation speed of 10 rpm, a feeder ro~ation speed of 20 rpm, a compression gauge pressure of 150 kg/cm2G and a roll surace temperature of 80C.
The sheet was pulverized by using an atomizer (manufactured by Fuji Paudal Co., Ltd,) under the following conditions: a rotation speed of 1300 rpm, and a pore opening si2e of screen of 1.5 mm.
rhe resulting powder was sieved with a sieve of 35 mesh to give a non-spherical TFE copolymer powder having a frictlonal packing ratio of 40.2 %, a bulk density (Pl) of 0.90 g/cc, an average particle size of 185 ~m, and a thermal stability ratio of 120.5 ~.
A cylindrical container of monel (inner diameter: 200 mm, height: 600 mm) having a heater wound therearound and also having a set of disc-like pans ~outer diameter: 185 mm, height: 20 mm, 12 stage~) arranged in the center of the container by meanC of a guide was used for fluorine gas treatment. Each pan was charged with 100 g of the TFE copolymer powder prepared in Preparation Example 1. After in~talling the set of - ~.3C~G3~
pans in the container, the container was washed with nitrogen gas to remove oxygen gag, and then heated to 25~C. Subsequently, a fluorine gas diluted with nitrogen gas (fluorine gas content: 10 % by volume) was introduced to the container and maintained ~or 120 minutes. After cooling, nitrogen gas was exhau~ted to obtain a thermally stabilized powder having a thermal stability ratio of 2 %. As a result of observing the powder by means of scanning type electron microscopy, the powder particle was non-spherical. The electron microscopic photograph (magnification: 100) is shown in Fig. 1.
The TFE copolymer powder prepared in Preparation Example 1 was subject to the same fluorine gas treat~ent as in Preparation Example 4 except that the treatment was carried out at 200C for 120 minutes by using a fluorine gas (fluorine gas content: 10 % by volume) to give a powder having a thermal stability ratio of`5 ~.
The TFE copolymer powder prepared in Preparation Example 1 was subject to the same fluorine gas treatment a~ in Preparation Example 4 except that the treatment was carried out at 250C for 180 minutes by using a fluorine gas (fluorine gas content: 5 % by volume) to give a powder having a thermal stability ratio of 11~.
The production of the sheet and pulverization in Preparation Example 1 were repeated by using the`
fluorine-gas-treated TFE copolymer powder prepared in Preparation Example 4 to obtain a powder. The powder was sieved with a sieve of 35 mesh to give à non-~pherical TFF copolymer powder having a frictional packing ratio o~
,~ .
~V~ci3~
32.3 %~ a bulk density ~Pl) of 0.95 g/cc, an average particle size of 190 ~m, and a thermal ~tability ratio of 2 %.
The TFE copolymer powder prepared in Preparation E~ample 2 was ~ubjected to the same fluorine gas treatment as in Preparation Example 4 except that the treatment was carried out at 200C for 120 minutes by using a fluorine gas (fluorine gas content: 10 % by volume) to give a powder having a thermal stability ratio of 9 %.
By using the TFE copolymer raw powder used in Preparation Example 1, tablets (diameter: 11 mm, thickness: 3 mm, weight: Q.8 g) were prepared by means of an automatic molding machine under a compression gauge pressure of 700 kg/cm2G.
The tablets were pulverized under the same conditions a~ in Preparation Example 1 and sieved to give a non-spherical TFE copolymer powder having a frictional packing ratio of 125 ~, a bulk density (Pl) of 0.62 g/cc, an average particle size of 233 ~m, and a thermal stability ratio of 76.5 ~.
Tablets were prepared in the same manner as in Comparative Preparation Example 1, and then pulverized in the same manner as in Preparation Example 2 to give a non-spherical TFE copolymer powder having a frictional packing ratio of 150 %, a bulk density (Pl) of 0.32 g/cc, an average particle size of 55 ~m, and a thermal stability ratio of 73 %.
A mold of 3000 m~ with a mold bumping was cleaned, and a silicone type mold-release compound was .
13~ 6 applied to the mold, and then dried. The mold was charged with 600 9 of the powder prepared in Preparation Example 1, and sealed. ~fter ~etting the mold to a roto-molding machine, the molding machine wa~ heated from room temperature to 360C for 40 minute~ while rotating biaxially at a revolution speed of g rpm and an autorotation speed of 23 rpm, and maintained at 360C for 60 minutes, following by air cooling for 30 minutes to mold a container. The outer and inner surfaces of the molded container were observed in viewpoints of appearance and foaming. The results are shown in Table 1.
The represented evaluation in Table 1 are based on the following standard.
(Appearance of outer surface) X o Partial surface defect~
O : Beautiful appearance (Appearance of inner surface~
X : Great undulation having continuous ball-like projections ~: Moderate undulation O : Good leveling property (Eoaming) X : Many bubbles or cells ~ : Some bubbles or cell~
O : No bubble or cell ~0 A container was molded in the same manner as in Example 1 except that the powder prepared in Preparation Example 8 wa~ used and the mold wa~ heated at 340C. The molded container wa~ observed to evaluate it~ appearance and foaming. The results are shown in Table 1.
- ' ~ ', ' .
. . .
.
13~3~6 - 13 -~
A container was molded in the ~ame manner as in Example 1 except that a spherical powder having a frictional packing ratio of 13.5 %, a bulk density of 0.98 g/cc, an average particle size of 320 ~m and a thermal stability ratio of 3 %. The molded container was observed to evaluate its appearance and foaming. The results are shown in Table 1.
Table 1 lQ
, _ ~
TFE Properties of Molded Container Example Copolymer No. Powder Outer Inner Foaming Appearance Appearance 1 Prep.Ex.l O ~ ~
(Neck portion) 2 " 4 0 0 0 3 " 5 0 0 0 4 " 6 0 0 0 " 7 0 0 0 6 " 8 0 0 0 Comp.
Ex. No.
1 Comp. Prep. O X X
Ex. 1 .
To the powders prepared in Preparation Examples 1 and 3 and Comparative Preparation Example 1 was added potassium hydrogen-sulfate as a melting agent. The powder wa~ melted and decomposed in a platinum ba~in, and then an ash content was di~solved in deionized water to prepare a sample solution. The sample ~olution~ were analyzed by means of atomic absorption analy~is ~L3~3Z6 (flameless) to determine the amounts o~ iron, chrom.ium and nickel present in the powders. The results are shown in Table 2.
Table 2 .
TFE Kind of Metal ~ppm) Example Copolymer No. Powder IronChromium Nickel 7 Prep.Ex.l 0.010.003 0.01 8 " 3 0.020.005 0.02 ~ , Comp.
15Ex. No.
3 Comp. Prep.
Ex. 1 o.s 0-04 0 3 As is clear from Table 2, according to the prèss method the powder is con~aminated with metals used in the mold.
To a bla~t-treated ~tainless steel plate were applied two primers ~or fluorine resin coating (EK-1083GB
and EK-1883GB, both available from Daikin Industries, Ltd.) to form a double layer primer coating, and then was baked. The primer coating was electrostatically coated with the powder prepared in Preparation Example 8 at a base plate temperature of 300C with the GX3300 Type electrostatic powder coating machine manufactured by Iwata Aircompressor Manufacturing~ Co., Ltd., and the resulting coating was baked at 340C.
After repeating the electrostatic powder coating operation three times one above the otber while shifting the application area so that a Rurface of each coating could be observed, the resulting three-layer .
i3~t;3~ 6 coating was baked at 340C for 120 minute~ to obtain a sample. The appearance of each coating surface was ob~erved and evaluated according to the following standard~ The results are shown in Table 3.
X : Many bubbles or cells ~ : Some bubbles or cells O : No bubble or cell COMPARATIVE EX~MPLE 4 By using the TFE copolymer powder o~
Comparative Preparation Example 2, the same coating and baking procedures as in Example 9 were repeated to prepare a coating, and then the appearance of the coating surfaces were observed. The result~ are -~hown in Table 3.
Table 3 . _ _ TFE First Second Third 20 Example Copolymer Coating Coating Coating No. Powder ~thickness) (thickness) (thickness) 9 Prep.Ex.8 O O O
tS00 ~m) (900 ~m) (1200 ~m) --- _ Comp.
Ex. No.
4 Comp. Prep. O X
Ex. 2 (200 ~m) (400 ~m~ -30 ~ - - - -~ ' .
A TFE/fluoro(vinyl ether) copolymer can be prepared, for example, by dispersion polymerization described in Japanese Tokkyo Kokai No. 189210/19~3~ or by emulsion polymerization described in Japanese Tokkyo Kokoku No.
20788/1983.
The powder of the present inventioll can be prepared by producing a sheet with rolls from a TFE
copolymer raw powder, and then pulverizing the sheet.
As the raw powder of TFE copolymer used in the process of the invention, there may be employed a dry powder prepared by dispersion polymerization described in Japanese Tokkyo ~okai No~ 189210/1983 or prepared by emulsion polymerization described in Japanese Tokkyo Kokoku No. 20788/1973. Since a dry powder prepared by emulsion polymerization contains an emulsifier or a coagulant, a dry powder prepared by dispersion polymerization is preferred in view of contaminant.
Production of a sheet with rolls is operative so that a sheet has a thickness of 0.05 to 5 mm, preferablly 0.1 to 3 mm.
The roll used in the present invention preferably comprises -two or more rolls which are ~A
-1.3~ i3,. ~
arranged in perpendicular, inverted L, or Z position.
Example~ are, for instance, a calender roll, mixing roll or the like. It is preferable to regulate the roll distance, rotation speed, pressure, temperature and the like. According to this method, since a large slide shearing force is applied to the copolymer, bubbles and cells in the copolymer can be released out of the copolymer to give a uniform and homogeneous sheet. The sheet produced by the method is uniform both in the surface and inner regions in comparison with a sheet produced by other press methods as described in U.S.
Patent No. 4,312,961, and can give the powder which satisfies the powder properties of the invention by the subsequent pulverizing step. The main defect of the press method is contamination of the TFE copolymer by a small amount of metal powder which is yielded due to abrasion between the metal molds at the pressing operation.
This contaminated TFE copolymer cannot be used for coat-ings or containers utili~ed in the semiconductor industry because contamination gives serious damages to semiconductors. In addition, since release o bubbles or cells in the raw powder particles requires a very high pressure according to the press method, a special equipment is needed.
As operation conditions for production of sheet, there is preferably employed such conditions that an operation temperature is 0 to 250C, particularly 30 to 200C, and the resulting sheet is transparent or translucent.
The thickness of the sheet is preferably 0.05 to 5 mm. When more than 5 mm a uniform sheet is hard to obtain because the shearing force to the outer surface portion is different from that to the inner portion. A
sheet thinner than 0.05 mm has a problem of productivity. The pulverizing step is carried out by applying impact force, shearing force and compre~sion force to the sheet with machines such a~ a cutter mill, hammer mill or jet mill. Operation temperature is 13~3~
generally -200 to 100C.
Thermal stability o TFE copolymers can be improved by known methods desclosed in Japanese Tokkyo Kokoku No. 23245/1971. Those methods may be employed in the present invention. A preferred thermal stabiliza-tion method to be applied to the invention is fluorine gastreatment, which can be applied eith~r to the copolymer obtained from the sheet production step or the copolymer obtained from the pulverizing step. As conditions of the fluorine gas treatment, there may be employed a fluorine gas concentration of 5 to 30 % by volume lthe other gas being an inert gas such as nitrogen gas), a pressure of 0 to 10 kgf/cm2G, and a reaction temperature of 5~ to 250C.
Thermal stability ratio of a copolymer is calculated according to the equation (III):
Thermal Stability Ratio (%) = (1 ~ ~ a~) x 100 (III) wherein MI(a): melt index of a sample without heat treatment measured at 372C according to MI(b): melt index of an sample which is su~jected to heat treatment at 380C for 5 hours.
The fluorine gas treatment is preferably car-ried out until the thermal stability ratio becomes 20%
or lower.
The TFE copolymer powder of the present invention is suitably used as materials for molded articles such as pipes, parts, lining container or tank utilized ~or production of semiconductors which are ser-iously impaired by contamination. Also the powder can be utilized for usual corrosion resistive lining, roto-molding ~e.g. for containers), roto-lining (e.g. for inner lining of pipes or joints) or the like. Those articles can be produced by various proce~sing methods such as electrostatic powder coating method, fluidized dip coating method, roto-molding method and roto-lining :~3~32~
method.
The pres~nt invention is more specifically described and explained by means oE the following Examples. It is to be understood that the present invention is not limited to the Examples and various changes and modifications may be made in the invention without departing from the spirit and scope thereof.
A dry powder of T~E/perfluoro(propyl vinyl ether) copolymer (98.5/1.5 molar ratio) was prepared according to the dispersion polymerization described in Japanese Tokkyo Kokai No. 189210/1983. From the dry powder (bulk density: 0.57 g/cc, average particle size:
400 to 600 ~m), a translucent sheet having a thickness of 1 mm was produced by using special compression rolls (Roller Compactor "MINI" manufactured by Freund Industries, Co., Ltd.) under the following conditions: a roll rotation speed o~ 10 rpm, a feeder rotation speed of 20 rpm, a compression gauge pressure of 150 kg/cm2G and a roll surface temperature of 50C.
The sheet was pulverized by using an atomizer ~manufactured by Fuji Paudal Co., Ltd.) under the following condition~: a rotation speed of 1300 rpm, and a pore opening size of screen of 1.5 mm.
The resulting powder was sieved with a sieve o~
35 mesh to give a non-spherical TFE copolymer powder having a frictional packing ratio of 35.5 %, a bulk density (Pl) of 0.92 g/cc, an average particle size of 205 ~m, and a thermal stability ratio of 75 %.
A tran~lucent sheet havin~ a thickness of 1 mm was produced according to the same procedures and by usin~ the same TFE copolymer as in Preparation Example 1, and then was pulverized with an atomizer (manufactured by Fu ji Paudal Co., Ltd.) under the following conditions: a rotation speed of 3900 rpm and a pore opening size of * Trade-mark `~.
. " ' . ' ' ~:
.
~3~63~
g screen of 0.5 mm.
The resulting powder was sieved with a sieve of 60 mesh to give a non-spherical TFE copolymer powder having a frictlonal packing ratio of 60.0 %, a bulk density (Pl) of 0.55 g/cc, an average particle size of 40 ~m, and a thermal stability ratio of 72.5 ~.
A dry powder (bulk density: 0.48 g/cc, average particle size: 400 to 800 ~m) of TFE/hexafluoropropylene copolymer (92/8 molar ratio) was prepared by dispersion polymerization. From the dry powder a translucent sheet having a thickness of 1.5 mm was produced by using special compression rolls (Roller Compactor "MINI"
manufactured by Freund Industries, Co., Ltd.~ under the following conditions: a roll rotation speed of 10 rpm, a feeder ro~ation speed of 20 rpm, a compression gauge pressure of 150 kg/cm2G and a roll surace temperature of 80C.
The sheet was pulverized by using an atomizer (manufactured by Fuji Paudal Co., Ltd,) under the following conditions: a rotation speed of 1300 rpm, and a pore opening si2e of screen of 1.5 mm.
rhe resulting powder was sieved with a sieve of 35 mesh to give a non-spherical TFE copolymer powder having a frictlonal packing ratio of 40.2 %, a bulk density (Pl) of 0.90 g/cc, an average particle size of 185 ~m, and a thermal stability ratio of 120.5 ~.
A cylindrical container of monel (inner diameter: 200 mm, height: 600 mm) having a heater wound therearound and also having a set of disc-like pans ~outer diameter: 185 mm, height: 20 mm, 12 stage~) arranged in the center of the container by meanC of a guide was used for fluorine gas treatment. Each pan was charged with 100 g of the TFE copolymer powder prepared in Preparation Example 1. After in~talling the set of - ~.3C~G3~
pans in the container, the container was washed with nitrogen gas to remove oxygen gag, and then heated to 25~C. Subsequently, a fluorine gas diluted with nitrogen gas (fluorine gas content: 10 % by volume) was introduced to the container and maintained ~or 120 minutes. After cooling, nitrogen gas was exhau~ted to obtain a thermally stabilized powder having a thermal stability ratio of 2 %. As a result of observing the powder by means of scanning type electron microscopy, the powder particle was non-spherical. The electron microscopic photograph (magnification: 100) is shown in Fig. 1.
The TFE copolymer powder prepared in Preparation Example 1 was subject to the same fluorine gas treat~ent as in Preparation Example 4 except that the treatment was carried out at 200C for 120 minutes by using a fluorine gas (fluorine gas content: 10 % by volume) to give a powder having a thermal stability ratio of`5 ~.
The TFE copolymer powder prepared in Preparation Example 1 was subject to the same fluorine gas treatment a~ in Preparation Example 4 except that the treatment was carried out at 250C for 180 minutes by using a fluorine gas (fluorine gas content: 5 % by volume) to give a powder having a thermal stability ratio of 11~.
The production of the sheet and pulverization in Preparation Example 1 were repeated by using the`
fluorine-gas-treated TFE copolymer powder prepared in Preparation Example 4 to obtain a powder. The powder was sieved with a sieve of 35 mesh to give à non-~pherical TFF copolymer powder having a frictional packing ratio o~
,~ .
~V~ci3~
32.3 %~ a bulk density ~Pl) of 0.95 g/cc, an average particle size of 190 ~m, and a thermal ~tability ratio of 2 %.
The TFE copolymer powder prepared in Preparation E~ample 2 was ~ubjected to the same fluorine gas treatment as in Preparation Example 4 except that the treatment was carried out at 200C for 120 minutes by using a fluorine gas (fluorine gas content: 10 % by volume) to give a powder having a thermal stability ratio of 9 %.
By using the TFE copolymer raw powder used in Preparation Example 1, tablets (diameter: 11 mm, thickness: 3 mm, weight: Q.8 g) were prepared by means of an automatic molding machine under a compression gauge pressure of 700 kg/cm2G.
The tablets were pulverized under the same conditions a~ in Preparation Example 1 and sieved to give a non-spherical TFE copolymer powder having a frictional packing ratio of 125 ~, a bulk density (Pl) of 0.62 g/cc, an average particle size of 233 ~m, and a thermal stability ratio of 76.5 ~.
Tablets were prepared in the same manner as in Comparative Preparation Example 1, and then pulverized in the same manner as in Preparation Example 2 to give a non-spherical TFE copolymer powder having a frictional packing ratio of 150 %, a bulk density (Pl) of 0.32 g/cc, an average particle size of 55 ~m, and a thermal stability ratio of 73 %.
A mold of 3000 m~ with a mold bumping was cleaned, and a silicone type mold-release compound was .
13~ 6 applied to the mold, and then dried. The mold was charged with 600 9 of the powder prepared in Preparation Example 1, and sealed. ~fter ~etting the mold to a roto-molding machine, the molding machine wa~ heated from room temperature to 360C for 40 minute~ while rotating biaxially at a revolution speed of g rpm and an autorotation speed of 23 rpm, and maintained at 360C for 60 minutes, following by air cooling for 30 minutes to mold a container. The outer and inner surfaces of the molded container were observed in viewpoints of appearance and foaming. The results are shown in Table 1.
The represented evaluation in Table 1 are based on the following standard.
(Appearance of outer surface) X o Partial surface defect~
O : Beautiful appearance (Appearance of inner surface~
X : Great undulation having continuous ball-like projections ~: Moderate undulation O : Good leveling property (Eoaming) X : Many bubbles or cells ~ : Some bubbles or cell~
O : No bubble or cell ~0 A container was molded in the same manner as in Example 1 except that the powder prepared in Preparation Example 8 wa~ used and the mold wa~ heated at 340C. The molded container wa~ observed to evaluate it~ appearance and foaming. The results are shown in Table 1.
- ' ~ ', ' .
. . .
.
13~3~6 - 13 -~
A container was molded in the ~ame manner as in Example 1 except that a spherical powder having a frictional packing ratio of 13.5 %, a bulk density of 0.98 g/cc, an average particle size of 320 ~m and a thermal stability ratio of 3 %. The molded container was observed to evaluate its appearance and foaming. The results are shown in Table 1.
Table 1 lQ
, _ ~
TFE Properties of Molded Container Example Copolymer No. Powder Outer Inner Foaming Appearance Appearance 1 Prep.Ex.l O ~ ~
(Neck portion) 2 " 4 0 0 0 3 " 5 0 0 0 4 " 6 0 0 0 " 7 0 0 0 6 " 8 0 0 0 Comp.
Ex. No.
1 Comp. Prep. O X X
Ex. 1 .
To the powders prepared in Preparation Examples 1 and 3 and Comparative Preparation Example 1 was added potassium hydrogen-sulfate as a melting agent. The powder wa~ melted and decomposed in a platinum ba~in, and then an ash content was di~solved in deionized water to prepare a sample solution. The sample ~olution~ were analyzed by means of atomic absorption analy~is ~L3~3Z6 (flameless) to determine the amounts o~ iron, chrom.ium and nickel present in the powders. The results are shown in Table 2.
Table 2 .
TFE Kind of Metal ~ppm) Example Copolymer No. Powder IronChromium Nickel 7 Prep.Ex.l 0.010.003 0.01 8 " 3 0.020.005 0.02 ~ , Comp.
15Ex. No.
3 Comp. Prep.
Ex. 1 o.s 0-04 0 3 As is clear from Table 2, according to the prèss method the powder is con~aminated with metals used in the mold.
To a bla~t-treated ~tainless steel plate were applied two primers ~or fluorine resin coating (EK-1083GB
and EK-1883GB, both available from Daikin Industries, Ltd.) to form a double layer primer coating, and then was baked. The primer coating was electrostatically coated with the powder prepared in Preparation Example 8 at a base plate temperature of 300C with the GX3300 Type electrostatic powder coating machine manufactured by Iwata Aircompressor Manufacturing~ Co., Ltd., and the resulting coating was baked at 340C.
After repeating the electrostatic powder coating operation three times one above the otber while shifting the application area so that a Rurface of each coating could be observed, the resulting three-layer .
i3~t;3~ 6 coating was baked at 340C for 120 minute~ to obtain a sample. The appearance of each coating surface was ob~erved and evaluated according to the following standard~ The results are shown in Table 3.
X : Many bubbles or cells ~ : Some bubbles or cells O : No bubble or cell COMPARATIVE EX~MPLE 4 By using the TFE copolymer powder o~
Comparative Preparation Example 2, the same coating and baking procedures as in Example 9 were repeated to prepare a coating, and then the appearance of the coating surfaces were observed. The result~ are -~hown in Table 3.
Table 3 . _ _ TFE First Second Third 20 Example Copolymer Coating Coating Coating No. Powder ~thickness) (thickness) (thickness) 9 Prep.Ex.8 O O O
tS00 ~m) (900 ~m) (1200 ~m) --- _ Comp.
Ex. No.
4 Comp. Prep. O X
Ex. 2 (200 ~m) (400 ~m~ -30 ~ - - - -~ ' .
Claims (4)
1. Powders of tetrafluoroethylene copolymer consisting essentially of particles of copolymer selected from the group consisting of a tetrafluoroethylene/hexa-fluoropropylene copolymer and a tetrafluoroethylene/fluo-ro(vinyl ether) copolymer, said particles having a non-spherical shape which is characterized by a sectional pro-file which comprises at least one linear section, wherein the frictional packing ratio is in the range of 20 to 100%, the average particle size (µ) is in the range of 100 to 500 µm, and the average particle size (µ) and the bulk density (p1) of the powders satisfy the following equation:
log µ < 2.45 p1 + 0.75.
log µ < 2.45 p1 + 0.75.
2. A process for preparing powders of tetra-fluoroethylene copolymers having a non-spherical particle shape, a frictional packing ratio of 20 to 100% and an average particle size of 5 to 500 µm, which comprises pro-ducing a sheet of a tetrafluoroethylene/hexafluoropro-pylene copolymer or a tetrafluoroethylene/fluoro(vinyl ether) copolymer with rolls, and pulverizing the sheet.
3. The process of claim 2, wherein the tetra-fluoroethylene copolymer in the form of sheet or in the pulverized form is subjected to fluorine gas treatment.
4. The process of claim 2, wherein the powder of tetrafluoroethylene copolymer is a powder which satis-fies the following equation:
log µ< 2.45 p1 + 0-75 in which µ represents an average particle size of the powder and p1 represents a bulk density of the powder.
log µ< 2.45 p1 + 0-75 in which µ represents an average particle size of the powder and p1 represents a bulk density of the powder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP307131/1986 | 1986-12-22 | ||
| JP30713186 | 1986-12-22 |
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| Publication Number | Publication Date |
|---|---|
| CA1306326C true CA1306326C (en) | 1992-08-11 |
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ID=17965400
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000554918A Expired - Lifetime CA1306326C (en) | 1986-12-22 | 1987-12-21 | Powders of tetrafluoroethylene copolymer and process for preparing the same |
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| Country | Link |
|---|---|
| US (2) | US4898779A (en) |
| EP (1) | EP0272659B1 (en) |
| JP (1) | JPH075743B2 (en) |
| KR (1) | KR950005998B1 (en) |
| CA (1) | CA1306326C (en) |
| DE (1) | DE3787628T2 (en) |
Families Citing this family (40)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5709944A (en) * | 1992-02-05 | 1998-01-20 | Daikin Industries, Ltd. | Polytetrafluoroethylene molding powder |
| WO1993016126A1 (en) * | 1992-02-05 | 1993-08-19 | Daikin Industries, Ltd. | Polytetrafluoroethylene powder for molding |
| WO1994002546A1 (en) * | 1992-07-21 | 1994-02-03 | E.I. Du Pont De Nemours And Company | Impact resistant polytetrafluoroethylene and preparation thereof |
| DE4331971A1 (en) * | 1993-09-21 | 1995-03-23 | Hoechst Ag | Polytetrafluoroethylene micropowder, its manufacture and use |
| US5968642A (en) * | 1993-12-22 | 1999-10-19 | Dupont-Mitsui Fluorochemicals Co., Ltd. | Article having a water-repellent fluororesin surface, and method for manufacturing the same |
| JP3074142B2 (en) * | 1996-04-22 | 2000-08-07 | 株式会社セイシン企業 | Composite powder for forming surface coating film of fluorine resin and method for producing the same |
| DE69717617T2 (en) * | 1996-04-24 | 2003-07-03 | Daikin Ind Ltd | FLUOROPOLYMER POWDER AND METHOD FOR THE PRODUCTION THEREOF |
| US5827608A (en) * | 1996-10-28 | 1998-10-27 | Minnesota Mining And Manufacturing Company | Method of forming a thermoplastic layer on a flexible two-dimensional substrate and powder for preparing same |
| WO1998041383A1 (en) * | 1997-03-17 | 1998-09-24 | Daikin Industries, Ltd. | Method of bonding and molding modified polytetrafluoroethylene moldings |
| BR9815719A (en) | 1998-03-11 | 2000-11-07 | Minnesota Mining & Mfg | Process of forming a thermoplastic layer, and, composite sheet material |
| US5863875A (en) * | 1998-06-24 | 1999-01-26 | The Lubrizol Corporation | Coating additive, coating composition containing said additive and method for coating a substrate using said coating composition |
| US7276287B2 (en) * | 2003-12-17 | 2007-10-02 | Eidgenössische Technische Hochschule Zürich | Melt-processible poly(tetrafluoroethylene) |
| ATE412018T1 (en) * | 1998-08-06 | 2008-11-15 | Eidgenoess Tech Hochschule | MELTS PROCESSABLE POLYTETRAFLUORETHYLENE |
| US6737165B1 (en) | 1998-08-06 | 2004-05-18 | Omlidon Technologies Llc | Melt-processible poly(tetrafluoroethylene) |
| JP2000229388A (en) * | 1999-02-09 | 2000-08-22 | Du Pont Mitsui Fluorochem Co Ltd | Hot-melt fluoroplastic-coated polytetrafluoroethylene molded object |
| IT1318595B1 (en) * | 2000-06-23 | 2003-08-27 | Ausimont Spa | THERMOPROCESSABLE TETRAFLUOROETHYLENE COPOLYMER MICROSPHERES. |
| JP2008133952A (en) * | 2001-04-26 | 2008-06-12 | Daikin Ind Ltd | Office automation equipment roll coated with fluorine-based polymer powder |
| JP4069746B2 (en) | 2001-04-26 | 2008-04-02 | ダイキン工業株式会社 | Fluoropolymer powder, production method thereof and coated article |
| WO2003006566A1 (en) * | 2001-06-18 | 2003-01-23 | Daikin Industries, Ltd. | Powder coating material |
| JP5135658B2 (en) * | 2001-08-02 | 2013-02-06 | ダイキン工業株式会社 | Polytetrafluoroethylene fine powder, polytetrafluoroethylene molded product obtained therefrom, and method for producing the same |
| EP2262045B1 (en) * | 2003-05-13 | 2015-07-08 | Asahi Glass Company, Limited | Process for producing an electrolyte polymer for polymer electrolyte fuel cells |
| PL1633825T3 (en) * | 2003-06-06 | 2009-04-30 | Whitford B V | Non-stick powder coating |
| JP2007536107A (en) * | 2004-05-04 | 2007-12-13 | ミヌタ・テクノロジー・カンパニー・リミテッド | Mold using non-crystalline fluororesin and method for producing the same |
| JP4614080B2 (en) * | 2004-06-14 | 2011-01-19 | 日立工機株式会社 | Electric tool |
| CN101002356B (en) * | 2004-08-18 | 2010-11-17 | 旭硝子株式会社 | Electrolyte polymer for fuel cells, process for its production, electrolyte membrane and membrane/electrode assembly |
| US7342081B2 (en) | 2004-12-28 | 2008-03-11 | 3M Innovative Properties Company | Fluoropolymer compositions, coated articles, and method of making the same |
| CA2599683A1 (en) | 2005-03-04 | 2006-09-14 | President And Fellows Of Harvard College | Method and apparatus for forming multiple emulsions |
| AU2006244358A1 (en) * | 2005-05-06 | 2006-11-16 | Akzo Nobel Coatings International B.V. | Powder coating base coat |
| US8007863B2 (en) | 2006-10-03 | 2011-08-30 | 3M Innovative Properties Company | Multi-layer articles and method for improving the release life of the same |
| WO2008058297A2 (en) * | 2006-11-10 | 2008-05-15 | Harvard University | Non-spherical particles |
| WO2010033200A2 (en) | 2008-09-19 | 2010-03-25 | President And Fellows Of Harvard College | Creation of libraries of droplets and related species |
| WO2011001833A1 (en) | 2009-06-30 | 2011-01-06 | ダイキン工業株式会社 | Composition and process for producing same, powder coating material, pellets, molded resin, and electric wire |
| EP2473263B1 (en) | 2009-09-02 | 2022-11-02 | President and Fellows of Harvard College | Multiple emulsions created using jetting and other techniques |
| WO2012162296A2 (en) | 2011-05-23 | 2012-11-29 | President And Fellows Of Harvard College | Control of emulsions, including multiple emulsions |
| WO2013006661A2 (en) | 2011-07-06 | 2013-01-10 | President And Fellows Of Harvard College | Multiple emulsions and techniques for the formation of multiple emulsions |
| WO2015069634A1 (en) | 2013-11-08 | 2015-05-14 | President And Fellows Of Harvard College | Microparticles, methods for their preparation and use |
| CN108289797B (en) | 2015-10-13 | 2022-01-28 | 哈佛学院院长及董事 | Systems and methods for making and using gel microspheres |
| JP6753546B1 (en) | 2019-05-31 | 2020-09-09 | ダイキン工業株式会社 | Primer for ethylene / tetrafluoroethylene copolymer paint |
| CN117561295A (en) * | 2021-06-30 | 2024-02-13 | 大金工业株式会社 | Method for producing polytetrafluoroethylene powder, and polytetrafluoroethylene powder |
| JP7265192B2 (en) | 2021-07-21 | 2023-04-26 | ダイキン工業株式会社 | powder coating composition |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3484503A (en) * | 1967-06-19 | 1969-12-16 | Du Pont | Blends of fluorinated polymers |
| US3655611A (en) * | 1968-08-09 | 1972-04-11 | Allied Chem | Cold flow resistant homogeneous polymers of tetrafluoroethylene and hexafluoropropene and process for preparing them |
| US3969435A (en) * | 1975-04-03 | 1976-07-13 | E. I. Du Pont De Nemours And Company | Process for finishing tetrafluoroethylene-hexafluoropropylene copolymers |
| US4001351A (en) * | 1975-04-03 | 1977-01-04 | E. I. Du Pont De Nemours And Company | Process for preparing tetrafluoroethylene-hexafluoropropylene copolymer blends |
| JPS6023689B2 (en) * | 1976-02-17 | 1985-06-08 | ダイキン工業株式会社 | Method for producing tetrafluoroethylene/hexafluoropropylene copolymer |
| US4248763A (en) * | 1978-07-22 | 1981-02-03 | Daikin Kogyo Co., Ltd. | Fluorine-containing resin composition having improved thermal stability |
| US4220511A (en) * | 1979-03-12 | 1980-09-02 | Radiation Dynamics, Inc. | Treatment of sintered poly-tetrafluoroethylene with irradiation and heat to produce a grindable material |
| DE3110193A1 (en) * | 1980-06-06 | 1982-09-30 | Hoechst Ag, 6000 Frankfurt | Improved process for the preparation of modified tetrafluoroethylene polymer powder having high bulk density and good flow properties |
| US4312961A (en) * | 1981-01-05 | 1982-01-26 | The Duriron Company, Inc. | Polymeric fluorocarbon rotomolding/rotolining composition |
| JPS5853960A (en) * | 1981-09-28 | 1983-03-30 | Daikin Ind Ltd | Composition for covering fluorine-contained resin |
| JPS58174407A (en) * | 1982-03-08 | 1983-10-13 | Daikin Ind Ltd | Fluorine-containing copolymer having improved extrudability |
| IT1183531B (en) * | 1985-03-29 | 1987-10-22 | Montefluos Spa | SLIDING GRANULAR COMPOSITIONS BASED ON FLUORO-ELASTOMERS |
| JPS6289711A (en) * | 1985-05-09 | 1987-04-24 | Mitsubishi Rayon Co Ltd | Acrylonitrile polymer fine particle aggregate and production thereof |
| US4743658A (en) * | 1985-10-21 | 1988-05-10 | E. I. Du Pont De Nemours And Company | Stable tetrafluoroethylene copolymers |
| US4714756A (en) * | 1985-10-23 | 1987-12-22 | E. I. Du Pont De Nemours And Company | Process for preparing melt processible tetrafluoroethylene copolymer granules |
| US4675380A (en) * | 1985-10-25 | 1987-06-23 | E. I. Du Pont De Nemours And Company | Melt-processible tetrafluoroethylene/perfluoroolefin copolymer granules and processes for preparing them |
| US4742122A (en) * | 1985-10-25 | 1988-05-03 | E. I. Du Pont De Nemours And Company | Melt-processible tetrafluoroethylene/perfluoroolefin copolymers and processes for preparing them |
| US4687708A (en) * | 1986-06-26 | 1987-08-18 | E. I. Du Pont De Nemours And Company | High build fluorocarbon polymer dispersions and their preparation |
-
1987
- 1987-12-08 JP JP62310257A patent/JPH075743B2/en not_active Expired - Lifetime
- 1987-12-19 DE DE87118890T patent/DE3787628T2/en not_active Expired - Lifetime
- 1987-12-19 EP EP87118890A patent/EP0272659B1/en not_active Expired - Lifetime
- 1987-12-21 US US07/135,217 patent/US4898779A/en not_active Expired - Lifetime
- 1987-12-21 CA CA000554918A patent/CA1306326C/en not_active Expired - Lifetime
- 1987-12-22 KR KR1019870014717A patent/KR950005998B1/en not_active IP Right Cessation
-
1989
- 1989-12-28 US US07/458,480 patent/US4977221A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0272659A2 (en) | 1988-06-29 |
| KR880007582A (en) | 1988-08-27 |
| JPS63270740A (en) | 1988-11-08 |
| EP0272659B1 (en) | 1993-09-29 |
| DE3787628D1 (en) | 1993-11-04 |
| KR950005998B1 (en) | 1995-06-07 |
| DE3787628T2 (en) | 1994-03-10 |
| US4977221A (en) | 1990-12-11 |
| JPH075743B2 (en) | 1995-01-25 |
| EP0272659A3 (en) | 1989-10-25 |
| US4898779A (en) | 1990-02-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 20040811 |