WO2001051560A1

WO2001051560A1 - Granular filled polytetrafluoroethylene and process for producing the same

Info

Publication number: WO2001051560A1
Application number: PCT/JP2000/009284
Authority: WO
Inventors: Masamichi Sukegawa; Michio Asano
Original assignee: Daikin Industries, Ltd.
Priority date: 2000-01-14
Filing date: 2000-12-27
Publication date: 2001-07-19

Abstract

A granular polytetrafluoroethylene which contains a static-free filler and is obtained by stirring in water a mixture comprising 98 to 50 wt.% polytetrafluoroethylene powder having an average particle diameter of 120 νm or smaller and 2 to 50 wt.% filler having water repellency imparted thereto by treatment with a phenylsilane coupling agent, in the presence of an organic liquid which forms a liquid/liquid interface with water and of a silicone compound and a surfactant, to granulate the mixture. The granular filled PTFE has a high apparent density, a small average particle diameter, a narrow particle size distribution, excellent powder flowability, and a small charge amount and gives a large molding extremely reduced in coloration.

Description

Akira Itoda Filler Polytetrafluoroethylene Granulated powder

Field of production and technology

The present invention provides a filler-free non-electrostatic polytetrafluoroethylene granular powder that can be manufactured without coloring a large molded product without coloring. Regarding the manufacturing method. Background technology

Conventionally, a mixture of a filler and polytetrafluoroethylene (PTFE) powder is stirred in water to granulate the mixture. The methods for producing PTFE granular powder include, for example, Japanese Patent Publication Nos. 43-8611, 44-226, 1919, and 48-8-3. No. 757, No. 1979-1785, Special Publication No. 566-8044, No. 571-187, No. 7 It has been proposed.

However, according to the manufacturing methods described in each of the above-mentioned public bulletins, the water stays in a water-philic filler such as glass fiber, and the so-called filler stays in the water. It causes separation.

Therefore, in the publication of Japanese Patent Publication No. 60-21669, a PTFE powder was prepared in the presence of a water-insoluble organic liquid and an anionic surface active agent. Filler that is water-repellent treated with a Mino-Silane Coupling Agent is granulated by stirring in water and granulating. A method for obtaining a granular powder has been proposed. According to this method, if a cylindrical shaped article having a large diameter is to be calcined and manufactured, the repellency of the filler is increased. Coloring caused by the Aminosilan printing agent used for water treatment occurs in the center of the molded product. In addition, prioritizing the solution of the color problem will reduce the gas opacity.

To solve this coloring problem, it has been proposed to use a phenylsilane coupling agent as a water-repellent treatment. .

For example, in the official gazette of Japanese Utility Model Publication No. 21885334, a glass fiber was treated with a phenylsilane coupling agent to make it water-repellent. Is stirred in water together with a water-insoluble organic liquid and granulated in a suspended state (underwater granulation method). The resulting granular powder gives a shaped product without coloring, but the granular powder itself appears to be dense, flowable, finely granulated, and non-electrostatic. There is room for improvement in this respect.

In the official gazette of Japanese Utility Model Publication No. 0 — 2 5 1 4 13, a glass fiber was treated with phenylsilane coupling agent for water repellency. One is agitated and granulated in water together with a water-insoluble organic liquid and a surfactant. Although the granular powder itself obtained by this method has been improved in terms of apparent density, powder flowability, fineness, and antistatic property, it has a cylindrical shape. When a molded product with a diameter of less than 50 mm is used, no color is recognized, but a molded product with a diameter of 50 mm or more is sintered. In that case, even a thin color will develop in the center.

In addition, it is disclosed that the addition of a silicone compound can suppress the coloration of molded products, and the publication of Japanese Patent Publication No. 60-212178 Etc. are described. However, if the silicone compound is added, the silicone compound is decomposed at the time of calcination, and gas is generated by the generated gas. As a result, the molded product is Let's do it. In particular, when the compounding amount is large, the distribution of the silicone compound becomes uneven, and the number of locally porous portions increases, and the mechanical strength and gas impermeability are reduced. In order to address this shortcoming, Japanese Unexamined Patent Publication No. Hei 4-1 853 3 4 discloses that the problem of foaming the amount to be used is to address this drawback. It is limited to a very small amount.

The inventors of the present invention have conducted intensive studies in view of the above-described problems, and as a result, have found that PTFE powder can be formed in water in the presence of an organic liquid and a surfactant that form a liquid-liquid interface with water. When the mixture with the filler is agitated and granulated, the presence of the silicone compound can solve the above-mentioned problems. Was found.

The purpose of the present invention is to provide a powder having a large apparent density, a small average particle size, a narrow particle size distribution, a small charge amount, and powder flowability. Even if it is a molded article with excellent physical properties, it is not colored (high whiteness) even if it is a large molded article, and it gives a molded article with excellent gas impermeability. The purpose is to provide a granular PTFE granular powder and its manufacturing method. Disclosure of the invention

According to the present invention, a PTFE powder having an average particle diameter of 120 or less and a filler treated with water repellent with a phenylsilane coupling agent at a weight ratio of 98 Z 2 The present invention relates to a filler-containing PTFE granular powder containing a surfactant and a silicone compound in a content of about 50/50.

As PTFE, tetrafluoroethylene (TFE) homopolymer or TFE 99 to 99.9999% by mole and perfluorovinylene 1 to 0.001 mol% Preference is given to the modified PTFE obtained by polymerization, and as a filler, a colorless transparent or white filler is preferred.

The silicone compound is preferably a silicone compound having a linear structure, and is preferably a nonionic surfactant as a surfactant. Hydrophobic segment and poly (oxylene), consisting of surfactants, especially poly (oxyalkylene) units having 3 to 4 carbon atoms It is preferable to use a nonionic surfactant having a hydrophilic segment which is a unitary unit, and a Z or anionic surfactant. It is better. As the anionic surfactant, for example, as a hydrophobic group, a perfluoroalkyl group or a perfluoroalkyl group may be used. Anionic surfactants containing a group are preferred.

The content of the silicone compound is 0.001 to 5 parts by weight with respect to the total of 0 parts by weight of the PTFE powder and the filler, and the surfactant is contained. Amount is preferably between 10 and 300 ppm

According to the present invention, a PTFE granular powder having a charge of 50 V or less is provided.

In addition, the PTFE granular powder of the present invention has a whiteness (Z value) of 80 or more, particularly 90 or more, and a whiteness (Z value) of the center. ) Is not less than 80 and gives a large cylindrical molded product with a direct diameter of not less than 5 Omm.

The present invention also provides a polytetrafluoroethylene powder having an average particle size of 120 m or less, from 98 to 50% by weight, and a phenylsilane powder. When the mixture of 12 to 50% by weight of the filer which has been subjected to the water repellent treatment with the printing agent is stirred in water and granulated, the water-liquid interface is reduced. It is characterized by being stirred and granulated in the presence of the organic liquid to be formed, the silicone compound and the surfactant. The present invention relates to a method for producing a polytetrafluoroethylene granular powder having a filler and a PTFE granular powder obtained by the production method. Brief explanation of the drawing

FIG. 1 is a schematic explanatory view of an apparatus used for examining the fluidity of a granular powder in the present invention.

FIG. 2 is a schematic cross-sectional view of a measuring instrument used for examining the gas permeability of the molded article obtained in the present invention. Best form for carrying out the invention The PTFE powder used in the present invention is obtained by the usual suspension polymerization method, for example, the single weight of TFE. Preferable powders, such as a copolymer of a monomer capable of copolymerization with TFE and a copolymer of TFE (modified PTFE), have an average particle size of 12 It is preferably 0 m or less, and more preferably 50 m or less, but the lower limit is determined by the pulverizer and the pulverization technique.

Examples of the monomer capable of copolymerizing with TF E include, for example, a compound represented by the formula (I):

C F C F O R (I)

[Wherein, R _f is a perfluoroalkyl having 1 to 10 carbon atoms.

9 ZOOM FLUOROS

F

(Wherein m is 0 or an integer of 1 to 4), or an organic group represented by the formula (III):

CF 3

CF CF ₂ CF _2- ^ 0-CF-CF _2- ) (EO

(Wherein, n is an integer of 1 to 4) represents an organic group represented by the general formula (1), or the like, or a perfluorovinyl ether represented by the formula:

The perfluoroalkyl group has 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, and the number of carbon atoms is determined to be a number within the above range. This has the effect of maintaining the property that it cannot be melt-formed and has excellent creep resistance.

The perfluoroalkyl group includes, for example, perfluoroethylene, perfluoroethyl, and non-fluoropropyl pill, and perfluoroalkyl pill. Fluorobutyl, perfluoropentyl, perfluoro, etc. can be applied to the mouth, but creep resistance and monomer cost In this regard, perfluoropropyl is preferred.

By setting the polymerization ratio of the monomer copolymerizable with the TFE to a ratio in the range of 1.0 to 0.01 mol%, excellent creep resistance is obtained. The effect is obtained.

In the present invention, a crusher having a hammer mill and a bladed rotor is prepared by mixing the PTFE powder, for example, in the presence of water or in a dry state. Particles obtained by pulverizing to a mean particle size of 12 Oym or less, and preferably 50 wm or less, by a pulverizer such as a pneumatic energy type pulverizer or an impact pulverizer. Used.

The average particle size of these particles is defined as a particle size within the above range. Therefore, the granular powder obtained by granulation is excellent in handling property, that is, excellent in powder powder flowability and apparent density, and is a molded product that can be obtained again. It has the effect of being superior in physical properties.

The filler used in the present invention is preferably a white or non-colored transparent filler, and is usually lyophilic or semi-philic. Therefore, the filler easily migrates to the aqueous phase and is not easily mixed with the PTFE powder, that is, the whole of the filler used is PTFE powder. However, there is a drawback that the agglomerated powder mixed with the water cannot be obtained, and a part of the powder remains in the treated water. This phenomenon is called filer separation.

In order to address this problem, the water-repellent filler is subjected to a water-repellent treatment in advance to reduce its surface activity and to reduce the surface activity of the particles of the PTFE powder. Get closer to sex. In the present invention, a silane coupling agent having a phenyl group is used as a compound for performing the water repellent treatment. This is a type of fiber whose silane coupling agent has the effect of suppressing the coloring of the molded article.

As the phenylesilane coupling agent, the compounds described in the official gazette of Japanese Patent Application Laid-Open No. 21853/44 can be used. For example, phenyl trimethyl silane, phenyl trimethyl silane, p-cloth phenyl trimethyl silicate Run, p — Bromomethyl trimethyl silane, diphenyl dimethyl silane, diphenyl dimethyl silane Runs, diphenylsilyldiols, etc. are given.

As the filler to be combined in the present invention, a white or colorless transparent filler is used because the molded product has high whiteness. It is done. Preferred colorless translucent or white filler and For example, glass fibers, glass beads, glass balloon, glass flakes, titanium oxide powder, oxidized zinc powder, Oxidized magnesium powder, calcium carbonate powder, aluminum fiber, aluminum beads, artificial myth, natural mystery, evening milk , Powdered calcium sulfate, powdered calcium sulfate, powdered aluminum borate, powdered potassium titanate, powdered aluminum titanate, Sulfuric acid hydroxide magnesium powder, titanium nitride powder, aluminum nitride powder, boron nitride powder, silicon nitride powder, silicon carbide powder, etc. Inorganic fiber or inorganic powder of the following: Tetrafluoroethylene-perfluoroalkyl vinyl One or more types of synthetic resin fibers such as ruthel copolymer (PFA) or powder, but not limited to these It is not something that is done. Also, unless you are particular about white chromaticity, you can use a polyoxybenzoyl ester (light yellow), polyimid, polyolefin, etc. Colored aromatic heat-resistant resin powders other than black, such as sulfide, may also be appropriately blended.

,

In the case of the filler m, the average particle size of the powder is 10 to 10

It is preferable that the average fiber length is 100 m to 100 m, but the average fiber length is 10 to 100 x m.

In order to obtain a mixture of the PTFE powder used in the present invention and the filler described above, for example, the PTFE powder having an average particle diameter of 120 m or less is used. The water-repellent-filled filler can be mixed with a milling machine, hen-shell mixer, flash-mixer, blender and kneading machine. It is only necessary to mix them evenly, and the mixing ratio is preferably 98 Z 2 to 50/50 by weight ratio of PTFE powder Z filler. H is 95/5 to 70

It is preferably 30. The organic liquid used in the present invention may be any organic liquid which forms a liquid-liquid interface with water and may be present as droplets in water. The liquid may form a liquid droplet and form a liquid-liquid interface, and may be a little soluble in water as long as it forms a liquid-liquid interface. Specific examples include post-recording such as 1-butanol and 11-pentanol, jet ether, and zip-out pipes. Ethers such as ruethers; methyl ketones, 2-ketones such as pentanone; pentanes, dodecane, etc. Aliphatic hydrocarbons; benzene, toluene, xylene and other aromatic hydrocarbons; methylene chloride, tetrachloroethylene, triglyceride Chloroethylene, kuroguchi home, kuroben benzene, trikuroguchi trifluorene, monofluorochrome Tan, difluorotetrachlorethane, 1,1,1,1-trichloroethane, 1,1,1-dichloro-2,2,3,3,3 3 — Pe Interfluoropropane, 1, 3 — Dichloro1, 1, 2, 2, 2, 3 _ Pentafluoroleon Propane, 1, 1 — Dichloro mouth 1, 2, 2, 2 — Trifluorene, 1,1-dichloro-1, 1-fluorophenol, etc., Rogenich, etc. You can use any of them. Of these, the hydrogenated hydrocarbons are preferred, and in particular, 1,1,1,1-trichloroethane, 1,1,1-dichloro-2,2 , 3, 3, 3 — Pen Fluoro mouth Proton, 1, 3 — Dichloro 1, 1, 1, 2, 2, 3 — Penta Fluoro mouth prop , 1,1-dichloro-2,2,2-Trichlorofluorocarbon, 1,1-dichloro-1-Fluoroethane, etc. Hydrogen ゃ Fluorocarbon is preferred. They are non-flammable and meet the requirements of Fluoro-Regulation. These organic liquids may be used alone or in combination of two or more. Okay.

The addition amount of the organic liquid forming the liquid-liquid interface is 30 to 80% (30 to 80% of the total amount of the PTFE powder and the filler). Weight%, the same shall apply hereinafter), and it is preferable that the weight ratio be 40 to 60%.

In the present invention, the granulation of the PTFE powder containing the filler proceeds in the droplets of the organic liquid forming the liquid-liquid-liquid interface between the water and the liquid. It is thought that the droplets are made smaller and more spherical, resulting in spheres with higher apparent density and smaller average particle size. In order to obtain granular particles close to the shape, a surfactant is coexisted.

As the surfactant, the force S at which various surfactants can be used, particularly a nonionic surface active agent or an anionic surfactant alone or Is preferably used in combination.

Particularly preferred surfactants are nonionic surfactants, and among them, poly (oxyalkylene) units having 3 to 4 carbon atoms. A segmented pore with a distinct hydrophobic segment and a poly (oxyethylene) unit, a distinct hydrophilic segment Preference is given to rutile glycols. The anionic surfactant may be a perfluoroalkyl group or a perfluoroalkyl group as a hydrophobic group. Anionic surfactants containing a group are preferred.

Segmented polyalkylene glycols having a hydrophobic segment and a hydrophilic segment include, for example, the formula (IV ):

R- OCH ₂ CH _2- ^ iA ¹ ^ CH ₂ CH ₂ O (IV)

(Where A ¹ is _{_{- CHCH 2 0 - -CH -CH 2}} CH 2 0 -

I or I

CH ₃ CH ₃

R is a hydrogen atom, an alkyl group or a aryl group, p is 0 to 200, preferably an integer of 5 to 200, q is 0 to 400, and Or an integer from 2 to 400). Of these, it is preferable that the point force for easily adsorbing to the PTFE resin, P is 15 to 40, and Q is 7 to 100. Commercially available products include, for example, Pronon # 208, Pronon # 104 and Pronon # 102 (all manufactured by Nihon Yushi Yushi Co., Ltd.). Nonionic surfactants) can be used.

Other than that, for example, polyoxylaminamides, alkylamine aminoxides, and polyoxyethylene Kir ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, soles Bi-fatty acid esters, polyoxyethylene esters Bi-fatty acid esters, glycerin esters, polyoxy Styrene alkylamines and their dielectrics can also be suitably used.

The anionic surfactants include, for example, higher fatty acids and their salts, alkyl sulfates, alkyl sulfonates, and alkylsulfonates. Known ones such as arylsulfonate and alkyl acrylate ester can be used, but particularly preferred anionic properties As a surfactant, higher alcohol sulfate ester salt, for example, sodium raurylsulfate, and one type of fluoroalkyl Group, especially a perfluoroalkyl group or a perfluoroalkyl group, especially a perfluoroalkyl group Fluorine-containing carboxylate-based or fluorine-containing sulfonate-based anionic surfactants are required. A typical compound is represented by the formula (V):

_{_{(? CH) X (CF 2}} CF 2) n m A 2 (V) or other formula (VI):

X (CF ₂ CFC 1) n (CH ₂ ) m A ² (VI)

(In the formula, X is a hydrogen atom, a fluorine atom or a chlorine atom, n is an integer of 3 to 10, m is an integer of 0 or 1 to 4, A is a hydroxyl group, and (Representing a sulfonic acid group or an alkali metal or ammonium residue thereof). The sales rolls include, for example, DS-101 manufactured by Daikin Industries, Ltd., which is an aqueous solution of ammonium perfluorophosphate. can give .

The amount of the surfactant to be added is 0.015%, preferably 0.1 to 0.3%, based on the total amount of the PTFE powder and the filler. Yes. The use of surfactants, especially nonionic or anionic surfactants, within this range results in a roughly spherical, small particle size and particle size distribution. It is a sharp and has excellent powder fluidity, and a granular powder with a large apparent density can be obtained.

The feature of the present invention is that a silicon compound coexists during granulation. By allowing the silicone compound to be present in the granular powder even after granulation, it is possible to suppress coloring during firing even in a large molded product.

As described above, the addition of the silicone compound has a problem of foaming during firing, but in the present invention, the silicone compound is relatively used. Even in a large amount, the coexistence of the surfactant allows the silicone compound to be emulsified and dispersed to a very small size due to the coexistence of the surfactant. The granulated compound is uniformly dispersed throughout the granulated particles and thus the entire molded article, and In addition to being able to suppress foaming, it is also possible to make the bubbles that are produced finer, and to fully utilize the color control of silicone compounds. It can be used to suppress the reduction of gas opacity.

The silicone compound used in the present invention is an organic silicone oligomer or polymer having a straight-chain, ring-like, or three-dimensional bridge structure. Is a liquid or a fluid, a resin or a rubber at room temperature, usually. Solution to be added Silicone compound as it is, a solution prepared by dissolving it in an organic solvent, or an emulsion prepared by dispersing it in water with a surfactant Can be used in the form of a display version.

Silicon compounds are described in, for example, Japanese Patent Publication No. 60-221178 and Japanese Patent Publication No. Hei 4-218534. The silicone compound is exposed, for example, the formula:

I [S i (R ¹ ) (R ² )-O] _n

(Wherein, R ¹ and R ² represent an aryl group, an aryl group, an aryl alkyl group, an alkyl aryl group or a hydrogen atom, n represents a liquid polymer having a linear chain structure represented by about 100 to 200),

Expression:

R

S i— O n

R ² Expression:

(Wherein R ¹ , R ² and n are the same as those described above), and are organic oligomers with an annular or three-dimensional bridge structure Or a polymer.

Specific examples include, but are not limited to, methylsilicon, dimethylsilicon, methylireno, and idyllicone. And mono- or co-polymers such as Monof-Silicone. In addition, epoxy-modified silicone, carboxyl-modified silicone, polyether-modified silicone, and epoxy-modified silicone Ether-modified silicone, carboxysil-poly X-only modified silicone, alcohol-modified silicone, alkyl-a It is also possible to use radical-polysilicone, amino-silicone, fluorine-silicone, etc.

Of these silicone compounds, the liquid form of a linear chain structure in which R ¹ and R ^{2 in} the above formula are both methyl groups. It is preferable that the series oil can greatly suppress the coloration and achieve a high whiteness even in a large-sized molded product.

The amount of the silicone compound to be mixed is 0.001 to 5 parts by weight with respect to the total of 100 parts by weight of the PTFE powder and the filler, preferably < 0.01 to 3 parts by weight, especially preferably 0.0 3 to 0.5 direct part. If the amount is less than 0.001 part by weight, the effect of suppressing color formation is reduced, and if the amount is more than 5 parts by weight, the center of the molded article becomes a glass. It is easy to reduce gas impermeability.

The process for producing the granular PTFE powder containing filler according to the present invention is limited to, for example, mosquito S, which can be produced by a process such as a nail polish, and is also limited to only this process. Not

Combine a filler that has been surface-treated with a fertilizing agent and a PTFE powder that has been ground to a particle size of 120 m or less in advance. Pour the mixture of the PTFE powder and the filler to be dry-premixed using a Lumixer into a granulation tank filled with ion-exchanged water. Then, an organic liquid which forms a liquid-liquid interface with water is added, and after adding the surfactant and the silicone compound, the mixture is stirred at room temperature and granulated.

The surfactant and silicone compound should be added at a time other than the time when

,

The addition of a mixture with a filler, the addition of water and an organic liquid that forms a liquid-liquid interface, and the like, can be performed at the liquid-liquid interface (that is, the interface between the organic liquid and water). It is preferable to add the organic liquid that forms the liquid-liquid interface between water and the start of granulation from the point of preferential adsorption to

Usually, it is preferable that the silicon compound be added after being dissolved in a small amount of an organic solvent. Examples of the organic solvent include ketones such as acetone; ethers such as dimethyl ether; and alcohols such as methyl alcohol. Octogenated hydrocarbons such as methylene chloride; carbohydrates such as hexane; aromatic hydrocarbons such as benzene; 1 one Dichloro 2, 2, 2-Trifluoroethane and other chlorofluorocarbons can be obtained.

In the present invention, the granulation may be performed using a combination of stirring and powder disintegration. Disintegration reduces the secondary particle size by partially disintegrating the appropriate size granules already formed as secondary aggregates of primary particles This can be achieved by means of high-speed stirring, for example by means of a disperser blade. Stirring and crushing may be performed in parallel at the same time, or stirring and crushing may be performed separately. By using agitation and crushing in combination, an excellent effect is obtained in that the apparent density is high and finely-granulated granules can be obtained. Here, the crushing mechanism for the powder particles is to partially crush the appropriate-sized granules already formed as secondary aggregates of the primary particles. Let's look at a mechanism that can reduce the secondary particle size of the lever.

The granular powder of the present invention is a filler which has been surface-treated with a PTFE powder pulverized to 120 or less and a phenylsilane coupling agent. And granulation by stirring in water, the powder and filler are not mixed in advance, but separately put into water and mixed with a surfactant and silica. After mixing to form a slurry by stirring in the coexistence of the surfactant compound, only the PTFE powder is poured into water to remove the surfactant and the silicone compound. Stir in the co-existence to mix and slurry, add the filler, and then stir in the presence of organic liquid to granulate. Can be manufactured at any time.

The filler-filled PTFE granular powder thus obtained has, for example, powder properties and molded article properties as if it were spiked. It is a granular powder.

(Physical properties of PTF E granular powder with filler)

Filler content: 2 to 50%

If it is less than 2%, the abrasion resistance and creep resistance will be reduced, and if it exceeds 50%, the specific characteristics of the fluororesin will be reduced. Both have a tendency to hurt the other material. In particular, 5 to 30% is preferable in terms of abrasion resistance, creep resistance, and slip characteristics.

Spotting density: 0.7 g Z cm ³ or more

If it is smaller than 0.7 g Z cm ³ , the filling amount of the mold will be small.

Flow—degree _: 6 times or more

If less than 5 times, the hopper fluidity is inferior. Eight times are particularly preferred.

Angle of repose: 40 degrees or less

Powders greater than 42 degrees are preferred for their fluidity and less than 40 degrees which are undesirable.

It's was, see what only density force 0. 9 g Z cm ³ or more on the 0 g

If it is less than Z cm ^3, it is less than 38 degrees, and if the apparent density is more than 1.0, it is less than 36 degrees.

Normally, the angle of repose of the powder becomes smaller as the apparent density becomes higher due to the influence of gravity. Therefore, the angle of repose of the powder obtained by the method of the present invention is also found to vary depending on the density, but can be obtained by conventional techniques. It is smaller than powder.

Your name, follow coming technology safe angle of repose of'm Ri gills are Ru powder end to, or only density seen 0. 6 g Z cm ³ or more on the 0. 9 g Z cm ³ less than the field Oh had 4 0 on degrees or more, or only density seen 0. 9 g Z cm ³ or more on 1. 0 g Z cm ³ less than the field Oh had 3 8 degrees or more on either only the density observed 1. 0 g Z cm ³ or more, it is 36 degrees or more.

Particle size distribution A: 0% of granular powder remaining on a sieve with openings of 1.7 mm

5% or less of granular powder remaining on sieve with openings of 85 μm

When the granular powder after granulation has a particle size distribution in this range, since the particle size is uniform, there is no stuffing in the mold, which is preferable. In particular, it is preferable that any of the granular powders present on the sieve with the opening of 1.7 mm and the opening of 85 / Xm be 0%.

Particle size distribution B: 50% by weight or more

When the granular powder after granulation has such a particle size distribution, it is preferable because the mold does not have a filling unevenness. In particular, it is preferably at least 60% by weight.

Average particle size: 500 Atm or less

If it is larger than 500 zm, it will not be possible to fill thin-walled molds. The point force for filling a thin-walled mold is particularly preferably 150 to 400 μπι.

Charge: 50 V or less

PTFE powder charged above 50 V adheres to static electricity not only in molding dies, but also in hoppers, feeders, etc., and consequently flows. Inhibits sex. Preferably, it is 10 V or less, and no decrease in fluidity occurs at that charge amount.

(Physical properties of molded products)

Whiteness (Ζ value): 80 or more, preferably 90 or more

In particular, a white chromaticity force s80 or more at the center of a columnar molded product having a diameter of 50 mm or more, and even 100 mm or more. Product is obtained. This is a feature of the present invention that coloring does not occur even in a large molded product.

Gas impermeability: good without leakage of gas. Although nitrogen gas is used as the measurement gas, the gas that is impermeable is not limited to nitrogen gas.

The addition of a relatively large amount of a silicone compound results in the formation of a porous material. However, in the present invention, the tendency of forming a porous material can be suppressed.

The method of measuring each property is as follows.

Spotting density: Measured according to JISK 6891-5.3.

Fluidity: Measured according to the method described in JP-A-3-2599295.

In other words, the measuring device is mounted on the support 12 as shown in Fig. 1 (corresponding to Fig. 3 described in Japanese Patent Application Laid-Open No. 3-2599295). Use the upper and lower hoppers 1 and 2 with the cores aligned and supported. The upper hopper 1 has a diameter of 74 mm for the inlet 3, a diameter of 12 mm for the outlet 4, a height of 23 mm from the inlet 3 to the outlet 4, and an outlet 4. There are five dividers, which make it easier to hold and drop the powder inside. The lower hopper 2 has a diameter of 76 mm at the inlet 6, a diameter of 12 mm at the outlet 7, a height of 120 mm from the inlet 6 to the outlet 7, and an upper hopper, As in the case of the first embodiment, a partition plate 8 is provided at the outlet 7. The distance between the upper hopper and the lower hopper is adjusted so that the distance between the partition plates is 15 cm. In Fig. 1, 9 and 10 are the outlet covers of the respective hoppers, and 11 is the receiver for the powder that has fallen.

To measure the fluidity, leave about 200 g of the powder to be measured in a room where the temperature is controlled at 23.5 to 24.5 ° C for 4 hours or more, and open the opening. After sifting through a 7 mm sieve, the test is carried out at the same temperature.

(I) First, put just one cup of the powder to be measured into the upper hopper 1 in a 30 ml capacity cup, and then immediately pull out the partition plate 5 to remove the powder to the lower part. Drop to Hopper. If it does not fall, wire it down. After the powder has completely dropped into the lower hopper 2, leave it for 15 ± 2 seconds, then pull out the partition plate 8 of the lower hopper, and the powder flows from the outlet 7 Observe whether the fall has occurred and judge that it has fallen within 8 seconds.

(II) The same measurement as above was repeated three times, and the flow that fell was observed.If it flowed out two or more times out of three times, the flowability was “good”. Judgment is made, and if it does not fall even once, it is judged that the liquidity is "bad". If only one of the three flows has flowed down, the same measurement must be performed twice, and if the two times have fallen, the flow of the powder eventually ends. The property is judged to be “good”, and if not, the liquidity is judged to be “bad”.

(III) For powders judged to be "good" in the above measurement, put two cups of the same volume of 30 cc powder into the upper hopper as described above. The measurement was performed in the same manner as above, and if the result was "good" for the fluidity, the number of cups of powder was gradually increased until the result was "bad". Continue to measure up to 8 glasses. For each measurement, the powder that has flowed out of the lower horn \ ° — from the previous measurement may be reused.

(IV) In the above measurement, the larger the amount of PTFE powder used, the more difficult it is to run off.

The fluidity of the powder is determined by subtracting 1 from the number of cups when the fluidity becomes “poor”.

Average particle size and granular size of granular powder ^ cloth A_: 1 from the top. Z

value

Standard sieve with openings of 7 mm, 850 m, 500 m, 300 IIm, 250 um and 18011 m (JIS

Z 8 0 1) on top of each other.

The FE granular powder was placed, the sieve was vibrated, and the fine PTFE granular powder was dropped downward sequentially, and the percentage of the PTFE granular powder remaining on each sieve was determined in%. That is, the cumulative percentage of the residual ratio (vertical axis) is plotted on the log probability paper with respect to the opening (horizontal axis) of each sieve, and these points are connected by a straight line. Then, a particle size having a ratio of 50% on this straight line is determined, and this value is defined as an average particle size. Also, the apertures are 1.7 mm, 85 nm, 500 m, 300 tim, 250 // m and 18

0 The weight% of the granular powder remaining on the 11 m sieve is defined as the particle size distribution A.

In this connection, "on" indicates the percentage of powder remaining on each sieve, and "pass" indicates the percentage of powder that passed.

Particle size distribution B: The weight ratio of particles having a diameter of 0.7.3 times the average particle size to all the particles, and 0.7 or 1.3 times the average particle size. Multiply by the value: Calculate by two and find the weight percentage by writing that point in the cumulative curve.

Angle of repose: Measured using Hosokawa Miclon Powder Test Yuichi.

The measurement was performed using a hand-held electrostatic meter SFM775 made by Ion Syst erns Inc.

(Whiteness) (Small molded product): 200 g of granulated powder was filled in a mold having a diameter of 50 mm, kept at a molding pressure of 49 MPa for 5 minutes, and obtained. Preformed product (diameter about 50 mm, thickness (50 mm) from room temperature to 365 ° C at a heating rate of 50 ° C / hr, and after maintaining at 365 ° C for 5.5 hours, the temperature rises to 50 ° C. The molded product cooled at a rate of / hr is divided approximately 25 mm (center part) from the end by a lathe, and the Z value of the center of the cut part is determined by the country. Measurements were made using a Nihon Denshoku colorimeter ZE-20000 based on the XYZ system Z value measurement method determined by the Illumination Committee.

Z value (white chromaticity) (Large molded product): Fill 200 g of the granulated powder into a mold having a diameter of 106 mm, hold at a molding pressure of 49 MPa for 5 minutes, The preform (diameter of about 106 mm and thickness of 100 mm) was heated from room temperature to 3651 at a heating rate of 25 / hr, and then heated at 365: 1. After holding for 1 hour, the molded product cooled at 2 ° / r was cut approximately 50 mm (center) from the end by a lathe, and then cut horizontally. The Z value of the center is measured using a Nihon Denshoku colorimeter ZE — 2000 based on the XYZ system Z value measurement method specified by the International Lighting Commission. Specified.

Gas impermeability — (small molded product) —:

The cylindrical molded product (directly about 50 mm, thickness 50 mm) prepared for the measurement of the whiteness was about 25 mm (middle, part) from the end, and the thickness was A 2 mm slice was cut out with a lathe and used as a sample. The gas permeability of the sample was examined using a gas impermeability measuring tool 20 shown in FIG. For the measurement, a 1-mm-thick support (a hole with a diameter of 1 mm and a diameter of 1 mm) was provided between the upper ring member 21 and the lower member 22 for pressurizing nitrogen gas at 5 mm intervals. The sample 24 is sandwiched through the plate-shaped disk) 23, and then tightened with a bolt. Thus, the upper ring member on the upper side of the sample 24 is placed. 21 Non-ionic surfactant in the center recess 25% of 1% by weight aqueous solution was added, and pressurized with nitrogen gas from the bottom with a pressure of 19.6 MPa. Bubbles were generated in the aqueous solution of nonionic surfactant. Gas impermeability was evaluated based on whether or not the gas exited. If no bubbles came out, X was given if bubbles came out.

Nitrogen gas impermeability (large molded product):

A large cylindrical molded product (diameter of about 106 mm, thickness of .100 mm) made for the measurement of the whiteness was about 50 mm from the end (center part). At this point, the sample was cut out with a lathe into a 2 mm-thick slice, and the sample was leaked in the same way as the gas impermeability test of a small molded product except for the sample. Was observed.

Next, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these.

Example 1

First, PTFE powder having an average particle size of 25 m after milling (modified PTFE in which 0.1 mol% of perfluoropropyl vinyl ether is co-polymerized) 9.3 Glass fiber (average diameter: 11 m, average fiber length: 30 ^ m) water-repellent with phenylsilane coupling agent, 5 kg (dry basis) 1.65 kg was premixed using a Henschel mixer with a content of 75 liters.

Pour 6 liters of ion-exchanged water into a granulation tank with a content of 10 liters, and further preliminarily mix the PTFE powder and glass fibers obtained by preliminarily mixing. I put 2 kg.

Next, perfluorooctanoic acid ammonium (anionic interface) at the concentration shown in Table 1 (concentration based on the total amount of PTFE powder and filler) is used. Activator) was added to the mixture by adding 40 ml of a 5% by weight aqueous solution of the surfactant, and 900 ml of Shiridi-Methylene was added. Dimethylsilicon (SH-200 manufactured by Toray Industries, Inc., U.S.A.

2 g of 5 c S) was added to the support B, and the mixture was stirred at 800 rpm at 25 ° C. and 2 ° C. for 5 minutes using a cone blade. In addition, stirring was carried out at 2,000 rpm for 5 minutes using a 100 mm diameter disperser blade.

Finally, 25 with stirring at 800 rpm using a cone blade. c Sized at 2 ° C for 10 minutes.

Finally, the temperature in the vessel was raised to 38 ° C over 20 minutes to stop the stirring, and the mixture was classified using a sieve with a mesh of 90 zm. The material was dried in an electric furnace at 1655 for 16 hours to obtain a PTFE granular powder containing the filler of the present invention. The above physical properties of the granular powder were examined. The results are shown in Table 1.

Examples 2 to 3

In Example 1, the filler of the present invention was introduced in the same manner as in Example 1 except that the amount of the silicone compound used was changed to the amount shown in Table 1. A PTFE granular powder was obtained, and the same test as in Example 1 was performed. The results are shown in Table 1.

Examples 4 to 6

In Example 1, the surfactant was a nonionic surfactant, a polyethylene glycol ethylene glycol block copolymer. (Polyoxypropyl segment molecule 100, polyoxyshylene segment molecule

8 0. According to the examples of the present invention, except for changing to Pronon # 10 02) manufactured by Yatsuo Yushi Co., Ltd. and using the amount shown in Table 1,

In the same manner as in Example 1, a filler-containing PTFE granular powder of the present invention was obtained, and the same test as in Example 1 was performed. « It is shown in Table 1.

Example 7

In Example 1, the surfactant was replaced by a non-ionic surfactant surfactant, ethylene glycol block of ethylene glycol. Kuco-Polymer (Polyoxypropylene segment molecular weight: 100,000; Polyoxyethylene segment molecular weight: 670. According to the same procedure as in Example 1 except that this product was manufactured by Yon Fats and Oils Co., Ltd., and the amount of water used was changed to the amount shown in Table 1. According to the method, the filler-filled PTFE granular powder of the present invention was obtained, and the same test as in Example 1 was performed. Table 1 shows the results.

Example 8

In Example 1, the surfactant was a nonionic surfactant, ethylene glycol block copolymer of propylene glycol, which is a nonionic surfactant. Molecule (molecular weight of polyoxypropylene segment: 200,000, molecular weight of polyoxyethylene segment: 800,000. Nihon Oil) The procedure was the same as in Example 1, except that the product was changed to Pronon # 208) manufactured by Toyo Co., Ltd., and the amount used was changed to the amount shown in Table 1. The filler-filled PTFE granular powder of the present invention was obtained, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative Examples 1-2

A comparative filer was prepared in the same manner as in Example 1 and Example 4 except that the silicone compound was not added in Example 1. A full PTFE granular powder was obtained, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative example

In Examples, Amino-Silane Coupling Agent (Japan A comparison was made in the same manner as in Example 1 except that glass fiber surface-treated with Al100 (manufactured by Nuniker Co., Ltd.) was used. A PTFE granular powder containing the filler was obtained, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 4

In the same manner as in Example 1 except that the surfactant was not used in Example 1, a PTFE granular powder containing a filler was used for comparison. Thus, the same test as in Example 1 was performed. The results are shown in Table 1.

table 1

Industrial applicability

As is evident from the results in Table 1, the PTFE granular powder containing filler obtained by the production method of the present invention has a molded product having a diameter of 50 mm. Coloring is hardly observed in large-sized molded products exceeding the above, and the apparent density is large, especially the particle size is small and the particle size distribution is sharp. In addition, it has excellent fluidity despite its small charge amount and small particle size.

Furthermore, when a white or transparent filler is used, the resulting molded article has a white chromaticity (Z-value) of 80 or more, especially a non-ionic interface. When the activator is used in combination, it is 90 or more, which is unprecedentedly high.

Claims

Scope of demand

1. Water-repellent fiber treated with polytetrafluoroethylene powder having an average particle size of less than 120 ^ m and a phenylsilane coupling agent And a filler in a weight ratio of 98 da 2 to 50/50, and further contains a surfactant and a silicone compound. Lo-ethylene granular powder

2. If the polytetrafluoroethylene is ethylene, the tetrafluoroethylene homopolymer or tetrafluoroethylene 99-99 9 9 9 Moleille% and Ref.Oro vinyl ether:! A granular powder according to claim 1, which is a modified polytetrafluoroethylene obtained by copolymerizing the powdered poly (ethylene glycol) with 0.01 to 0.1 mol%.

3. The granular powder according to claim 1 or 2, wherein the filler is a colorless transparent or white filler.

4. The granular powder according to any one of claims 1 to 3, wherein the silicone compound is a silicone compound having a linear structure.

5. The silicone compound was added in an amount of 0.001 to 5 parts by weight with respect to 100 parts by weight of the total amount of the polytetrafluoroethylene powder and the filler. The granular powder according to any one of claims 1 to 4, which includes claims.

6. A method according to any one of claims 1 to 5, wherein the surfactant is a nonionic surfactant and Z or an anionic surfactant. The granular powder described.

7. The above-mentioned surfactant is a hydrophobic segment composed of a poly (oxyalkylene) unit having 3 to 4 carbon atoms and a poly (oxoethylene) unit. With a hydrophilic segment consisting of The granular powder according to any one of claims 1 to 6, which is a non-ionic surfactant.

8. The anion as described above, wherein the surfactant contains a perfluoroalkyl group or a perfluoroalkyl group as a hydrophobic group. The granular powder according to any one of claims 1 to 6, wherein the granular powder is a water-soluble surfactant.

9. The granular powder according to any one of claims 1 to 8, wherein the surfactant is contained in an amount of 10 to 300 ppm.

10. The granular powder according to any one of claims 1 to 9, wherein the amount of charge is 50 V or less.

11. The granular powder according to any one of claims 1 to 10, which provides a molded product having a white chromaticity (Z value) of 80 or more.

12. A range of claims from 1 to 11 in which a molded article having a columnar molded article having a diameter of 50 mm or more and having a white chromaticity (Z value) at the center of the core of not less than 80 is given. The granular powder according to any one of the above items.

13. The granular powder according to any one of claims 1 to 12, which provides a molded product having a white chromaticity (Z value) of 90 or more.

14. 98-50% by weight of polytetrafluoroethylene powder having an average particle size of 120 / xm or less and repellent with phenylene silane coupling agent When a mixture of 2 to 50% by weight of the water-treated filler is agitated and granulated in water, an organic liquid or silicon that forms a liquid-liquid interface with water is used. Granulated by stirring in the presence of an organic compound and a surfactant in the form of a filler containing polytetrafluoroethylene. The final manufacturing method.

15. Claimed porphyra-tetrafluoroethylene granular powder containing filler obtained by the production method according to claim 14.