JP4698022B2 - Method for producing filled polytetrafluoroethylene molding powder - Google Patents
Method for producing filled polytetrafluoroethylene molding powder Download PDFInfo
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- JP4698022B2 JP4698022B2 JP2000398811A JP2000398811A JP4698022B2 JP 4698022 B2 JP4698022 B2 JP 4698022B2 JP 2000398811 A JP2000398811 A JP 2000398811A JP 2000398811 A JP2000398811 A JP 2000398811A JP 4698022 B2 JP4698022 B2 JP 4698022B2
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- 239000000843 powder Substances 0.000 title claims description 64
- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims description 46
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims description 46
- 238000000465 moulding Methods 0.000 title claims description 22
- -1 polytetrafluoroethylene Polymers 0.000 title claims description 10
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000002245 particle Substances 0.000 claims description 33
- 239000000945 filler Substances 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 17
- 239000002002 slurry Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000011362 coarse particle Substances 0.000 claims description 7
- RIQRGMUSBYGDBL-UHFFFAOYSA-N 1,1,1,2,2,3,4,5,5,5-decafluoropentane Chemical compound FC(F)(F)C(F)C(F)C(F)(F)C(F)(F)F RIQRGMUSBYGDBL-UHFFFAOYSA-N 0.000 claims description 6
- COAUHYBSXMIJDK-UHFFFAOYSA-N 3,3-dichloro-1,1,1,2,2-pentafluoropropane Chemical compound FC(F)(F)C(F)(F)C(Cl)Cl COAUHYBSXMIJDK-UHFFFAOYSA-N 0.000 claims description 4
- MSSNHSVIGIHOJA-UHFFFAOYSA-N pentafluoropropane Chemical compound FC(F)CC(F)(F)F MSSNHSVIGIHOJA-UHFFFAOYSA-N 0.000 claims 1
- 239000007788 liquid Substances 0.000 description 15
- 238000003756 stirring Methods 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 10
- 238000005469 granulation Methods 0.000 description 9
- 230000003179 granulation Effects 0.000 description 9
- 238000009826 distribution Methods 0.000 description 7
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- 238000001125 extrusion Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000009835 boiling Methods 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000007906 compression Methods 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 229920002545 silicone oil Polymers 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- FJKIXWOMBXYWOQ-UHFFFAOYSA-N ethenoxyethane Chemical compound CCOC=C FJKIXWOMBXYWOQ-UHFFFAOYSA-N 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- PHQOGHDTIVQXHL-UHFFFAOYSA-N n'-(3-trimethoxysilylpropyl)ethane-1,2-diamine Chemical compound CO[Si](OC)(OC)CCCNCCN PHQOGHDTIVQXHL-UHFFFAOYSA-N 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 description 1
- SWYZNMNIUXTWTF-UHFFFAOYSA-N (4-chlorophenyl)-trimethoxysilane Chemical compound CO[Si](OC)(OC)C1=CC=C(Cl)C=C1 SWYZNMNIUXTWTF-UHFFFAOYSA-N 0.000 description 1
- BOSAWIQFTJIYIS-UHFFFAOYSA-N 1,1,1-trichloro-2,2,2-trifluoroethane Chemical compound FC(F)(F)C(Cl)(Cl)Cl BOSAWIQFTJIYIS-UHFFFAOYSA-N 0.000 description 1
- BLTXWCKMNMYXEA-UHFFFAOYSA-N 1,1,2-trifluoro-2-(trifluoromethoxy)ethene Chemical compound FC(F)=C(F)OC(F)(F)F BLTXWCKMNMYXEA-UHFFFAOYSA-N 0.000 description 1
- UJIGKESMIPTWJH-UHFFFAOYSA-N 1,3-dichloro-1,1,2,2,3-pentafluoropropane Chemical compound FC(Cl)C(F)(F)C(F)(F)Cl UJIGKESMIPTWJH-UHFFFAOYSA-N 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 229910000906 Bronze Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- QYKIQEUNHZKYBP-UHFFFAOYSA-N Vinyl ether Chemical compound C=COC=C QYKIQEUNHZKYBP-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- ZZNQQQWFKKTOSD-UHFFFAOYSA-N diethoxy(diphenyl)silane Chemical compound C=1C=CC=CC=1[Si](OCC)(OCC)C1=CC=CC=C1 ZZNQQQWFKKTOSD-UHFFFAOYSA-N 0.000 description 1
- OLLFKUHHDPMQFR-UHFFFAOYSA-N dihydroxy(diphenyl)silane Chemical compound C=1C=CC=CC=1[Si](O)(O)C1=CC=CC=C1 OLLFKUHHDPMQFR-UHFFFAOYSA-N 0.000 description 1
- AHUXYBVKTIBBJW-UHFFFAOYSA-N dimethoxy(diphenyl)silane Chemical compound C=1C=CC=CC=1[Si](OC)(OC)C1=CC=CC=C1 AHUXYBVKTIBBJW-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000011361 granulated particle Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 1
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 1
- MQWFLKHKWJMCEN-UHFFFAOYSA-N n'-[3-[dimethoxy(methyl)silyl]propyl]ethane-1,2-diamine Chemical compound CO[Si](C)(OC)CCCNCCN MQWFLKHKWJMCEN-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- PARWUHTVGZSQPD-UHFFFAOYSA-N phenylsilane Chemical compound [SiH3]C1=CC=CC=C1 PARWUHTVGZSQPD-UHFFFAOYSA-N 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- FZHAPNGMFPVSLP-UHFFFAOYSA-N silanamine Chemical compound [SiH3]N FZHAPNGMFPVSLP-UHFFFAOYSA-N 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000012756 surface treatment agent Substances 0.000 description 1
- 238000010558 suspension polymerization method Methods 0.000 description 1
- 229950011008 tetrachloroethylene Drugs 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- JCVQKRGIASEUKR-UHFFFAOYSA-N triethoxy(phenyl)silane Chemical compound CCO[Si](OCC)(OCC)C1=CC=CC=C1 JCVQKRGIASEUKR-UHFFFAOYSA-N 0.000 description 1
- ZNOCGWVLWPVKAO-UHFFFAOYSA-N trimethoxy(phenyl)silane Chemical compound CO[Si](OC)(OC)C1=CC=CC=C1 ZNOCGWVLWPVKAO-UHFFFAOYSA-N 0.000 description 1
- 239000003799 water insoluble solvent Substances 0.000 description 1
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- Processes Of Treating Macromolecular Substances (AREA)
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Description
【０００１】
【発明の属する技術分野】
本発明は、微細なポリテトラフルオロエチレン（以下、ＰＴＦＥという）粉末と充填材から、造粒によって平均粒径が小さくかつ粒度分布が狭い充填材入りＰＴＦＥ成形用粉末を製造する方法に関する。
【０００２】
【従来の技術】
ＰＴＦＥ粉末は、融点以上の温度においても流動性が乏しいため、それを成形するに際しては圧縮予備成形・焼成という方法が採られている。このためＰＴＦＥ成形用粉末自体の性質が、該粉末の成形性や該粉末から得られる成形品の物性に大きな影響を与える。そこでＰＴＦＥ成形用粉末に要求される特性として、金型へ充填し易いよう粉末流動性が良いこと、できるだけ小さな金型で圧縮予備成形ができるように見掛密度が大きいこと、できるだけ小さな予備成形圧力によって緻密な成形品が得られるよう粉末の一次粒子の粒径ができるだけ小さいことなどが要求されている。
【０００３】
このような特性を得る方法として、従来、懸濁重合法により得られるＰＴＦＥ粗粒子を微粉砕し、次いでこれを造粒し二次粒子を形成させることが提案されている。この造粒方法の主なものは、水に不溶性又は難溶性の有機液体と水との混合液体中に上記微粉砕ＰＴＦＥ粉末を添加し、０〜１００℃の温度で撹拌する方法（特公昭４４−２２６１９号公報）と上記微粉砕ＰＴＦＥ粉末に有機液体を噴霧しながら当該粉末に転動作用と解砕作用を与えて造粒する方法（特公昭４３−６２９０号公報）との二つに大きく分けられる。
【０００４】
しかしながら、前者の方法は水に不溶性の有機液体としてトリクロロトリフルオロエタン等の有機液体を使用するため環境汚染問題等があり、近年はこの方法を忌避する傾向がある。さらにこの方法では造粒粉末から充填材が脱離し易いという問題がある。一方、後者の方法は有機液体を比較的自由に選択できるため、塩素系有機液体に起因する環境汚染問題を回避することはできるが、得られる造粒粉末は、前者の方法によって得られる造粒粉末に比べて見掛密度及び粉末流動性が低いという問題がある。
【０００５】
またこれらいずれの方法においても平均粒径が小さくかつ粒度分布が狭い充填材入りＰＴＦＥ成形用粉末は得られていない。近年リサイクルなどの環境問題より成形後の切削ロスを最小限にする必要があり、できるだけ最終製品に近い金型で成形することが要求されている。そのためとくにスリット幅の狭い成形金型による成形が必要な場合は、上記方法で製造されたＰＴＦＥ粉末を篩にかけて粒径の小さな粉末のみ取り出して成形するなどの処理が行われていた。
【０００６】
【発明が解決しようとする課題】
そこで本発明の目的は、このような篩い分けを行う必要がなく、造粒によって直接上記成形に使用することが可能な流動性、成形性に優れた充填材入りＰＴＦＥ成形用粉末を製造する方法を提供することにある。本発明の目的はまた、ＰＴＦＥと充填材の脱離がなく、かつ得られる粉末の粒径コントロールが容易であり、また粒度分布が狭い充填材入りＰＴＦＥ成形用粉末を製造する方法を提供することにある。
【０００７】
【課題を解決するための手段】
すなわち本発明によれば、平均粒径１００μｍ以下のＰＴＦＥ粉末と充填材をデカフルオロペンタンまたはジクロロペンタフルオロプロパン中で撹拌してスラリーとし、これを粒径２００〜１０００μｍの粗粒子として成形押出しし、さらに水中で撹拌して整粒することを特徴とするＰＴＦＥ成形用粉末の製造方法が提供される。
【０００８】
【発明の実施の形態】
本発明に用いられるＰＴＦＥ原料粉末は、平均粒径が１００μｍ以下、好ましくは５〜１００μｍ、とくに好ましくは１０〜５０μｍのものであり、一般には懸濁重合法によって得られるテトラフルオロエチレン（以下、ＴＦＥという）単独重合体、あるいはＴＦＥと共重合可能な単量体を２重量％以下、好ましくは１重量％以下を共重合したＴＦＥ共重合体の粗粉末を微粉砕することによって得ることができる。平均粒径が１００μｍを越えるような粉末から得られる造粒粉末は粉末流動性や見掛密度が劣り、気孔の多い成形品ができ易いので好ましくない。
【０００９】
上記ＴＦＥ共重合体における共重合可能な単量体としては、ヘキサフルオロプロピレンで代表される炭素数３以上のパーフルオロアルケンやパーフルオロ（メチルビニルエーテル）、パーフルオロ（エチルビニルエーテル）、パーフルオロ（プロピルビニルエーテル）などのパーフルオロ（アルキルビニルエーテル）などを挙げることができる。
【００１０】
本発明において使用される充填材にはとくに限定はなく、通常成形用ＰＴＦＥ粉末と混合使用されているものであれば如何なるものでもよい。具体的には、ガラス、カーボン、グラファイト、アルミナ、マイカ、炭化珪素、窒化硼素、酸化チタン、ブロンズ、金、銀、銅、ニッケル、ステンレス、二硫化モリブデンなどの粉末または繊維状粉末などを例示することができる。ＰＴＦＥに対する充填材の配合量は、両者の合計量を１００重量部とするときに５〜４０重量部、とくに１５〜２５重量部の範囲とするのが好ましい。
【００１１】
本発明でＰＴＦＥ粉末と充填材とを撹拌してスラリーとするために使用される水不溶性有機液体は、ジクロロペンタフルオロプロパンまたはデカフルオロペンタンである。これらは勿論２種以上混合して用いてもよく、また各種異性体がある場合はそれぞれ単独であるいは混合物として使用することができる。
【００１２】
これら水不溶性有機液体の中では、ＰＴＦＥ粉末を湿潤し易くそれ故充填材との混合及び造粒が容易になるところから、２５℃における表面張力が２５ダイン／ｃｍ以下のものが好ましい。またスラリー状態で造粒機を通過する間の有機液体の揮発をできるだけ少なくするために、沸点が４０〜８０℃、とくに５０〜６０℃程度のものを選択することが望ましい。
【００１３】
本発明においては先ず上記水不溶性有機液体中でＰＴＦＥ粉末と充填材を撹拌することによってスラリーを形成させる。このときの水不溶性有機液体の使用量は任意に選択することができるが、ＰＴＦＥ粉末と充填材の合計量１００重量部当り、１００〜２００重量部程度の範囲が最適である。
【００１４】
充填材として親水性または半親水性のものを使用する場合には、ＰＴＦＥに対する親和性を付与するため表面処理剤で表面処理したものを使用するかあるいはスラリー形成に際して親和性付与剤を添加しておくことが望ましい。このような目的に使用できる表面処理剤乃至は親和性付与剤としては、アルコキシシラン結合を有する化合物、とりわけアミノ基を有するアルコキシシラン化合物が好適である。具体的にはγ−アミノプロピルトリエトキシシラン、Ｎ−（β−アミノエチル）−γ−アミノプロピルトリメトキシシラン、Ｎ−（β−アミノエチル）−γ−アミノプロピルメチルジメトキシシラン、アミノフェニルトリエトキシシランのようなアミノシラン、フェニルトリメトキシシラン、フェニルトリエトキシシラン、ｐ−クロロフェニルトリメトキシシラン、ジフェニルジメトキシシラン、ジフェニルジエトキシシラン、ジフェニルシランジオールのようなフェニルシラン、シリコーンオイルなどを挙げることができる。またＰＴＦＥのディスパージョンもこのような目的に使用することができ、造粒粉末からの充填材の脱離防止に効果的である。
【００１５】
スラリー形成においてはとくに加温する必要はなく、大気温近辺で行えばよい。また撹拌速度もとくに高速にする必要がなく、装置によっても異なるが例えば１０〜１００ｒｐｍ程度で充分であり、また撹拌時間も１０分程度であれば充分である。
【００１６】
本発明においてはこのようなスラリーから成形押出によって２００〜１０００μｍ程度の粒径の粗粒子を得るものであって、スラリー状のＰＴＦＥ混合物が連続的あるいは断続的に押出されるものであればその方法にはとくに限定はない。例えば放射状に取り付けられた２〜４個のローラーが公転しながら固定されたスクリーンダイ（打ち抜き金網）上を摩擦抵抗によって自転しかつスラリーをスクリーンダイの孔から下部に押出成形される半乾式ロール型造粒機、スクリュー押出造粒機、ギヤーロール押出造粒機などの市販の押出装置を用いて造粒することができる。スクリーンの径の大きさを適宜選択することにより所望粒径の粒子を得ることができる。
【００１７】
このようにして得られる水不溶性有機液体を包含するＰＴＦＥ粒子は、次いで水中で撹拌下に整粒され、流動し易いような丸みを帯びた形状に変形される。使用される水の量は、ＰＴＦＥ粒子１００重量部当り、１００〜５００重量部程度の範囲が適当である。得られる造粒粒子の硬さ、表面状態、流動性などは、整粒時の温度、時間、撹拌速度などによって若干異なってくる。これらは処理槽の大きさや形状、あるいは使用した水不溶性有機溶媒の種類等によっても異なるが、例えば、１０〜７０℃程度の温度、１００〜１０００ｒｐｍで１０〜１８０分程度の時間の撹拌を行えばよい。一般には最初に低温で撹拌し、徐々に昇温して水不溶性溶媒の蒸発除去を行うようにするのがよい。
【００１８】
上記方法により整粒後、分離乾燥して得られるＰＴＦＥ造粒粉末は、従来の固液混合造粒法で得られたＰＴＦＥ造粒粉末よりも粒度分布が狭く、流動性、成形性に優れており、圧縮成形用原料として有用である。
【００１９】
【実施例】
以下、実施例により本発明を具体的にに説明する。尚、実施例及び比較例において使用した原料及び得られたＰＴＦＥ成形用粉末の評価方法は以下の通りである。
【００２０】
１ 原料
（ａ）ＰＴＦＥ原料粉末：テフロン７−Ｊ（三井・デュポンフロロケミカル社製）
（ｂ）充填材
コークス粉末：日本カーボン社製（平均粒径２１μｍ）
グラファイト粉末：オリエンタル産業社製（平均粒径２１μｍ）
（ｃ）水不溶性有機液体
１，３−ジクロロ−１，１，２，２，３−ペンタフルオロプロパン：ＨＣＦＣ２２５ｃｂ（２５℃における表面張力１６．７ダイン／ｃｍ、沸点５６℃）
１，１，１，２，３，４，４，５，５，５−デカフルオロペンタン：ＨＦＣ４３−１０ｍｅｅ（２５℃における表面張力１４．１ダイン／ｃｍ、沸点５５℃、三井・デュポンフロロケミカル社製）
パークロロエチレン：ＰＣＥ（２０℃における表面張力３２．３ダイン／ｃｍ、沸点１２１．２℃）
（ｄ）親和性付与剤
シランカップリング剤：ＫＢＭ−６０３（信越化学社製）
シリコーンオイル：ＳＨ−２００信越化学社製）
ＰＴＦＥディスパージョン：固形分３０ｗｔ％
【００２１】
２ 物性評価方法
（ａ）平均粒径：セイシン企業社製ＲＰＳ−９５型により測定
上から順に、１４、１６、２０、２８、３５、４８、７０、１００メッシュの標準篩を８段重ねて用い、各篩上に残る粉末の重量を求め、この各重量に基づいて対数確率紙上で、１６重量％、５０重量％及び８４重量％の粒径を求め、粒度分布の広狭の判断基準とした。また１００メッシュパスの値を調べ、微粉の割合の尺度とした。
（ｂ）見掛密度：ＡＳＴＭ Ｄ−１４５７に従い測定
（ｃ）引張特性：造粒粉末を６００ｋｇ／ｃｍ2で予備成形し、３８０℃で３０分間焼成し、厚さ２ｍｍの平板を得た。これからＡＳＴＭ Ｄ−６３８に従い試験片を打ち抜き、伸び及び引張強度を測定した。
（ｄ）収縮率：ＡＳＴＭ Ｄ−１４５７に従い比重測定用サンプルを作成し、この周囲長と金型から収縮率を測定した。
【００２２】
［実施例１］
３Ｌの造粒槽にＰＴＦＥ２０１ｇ、コークス粉末９３ｇ、グラファイト粉末６ｇ計３００ｇを計量し、これにシランカップリング剤０．１２７ｇ、シリコーンオイル０．０６ｇ及びＰＴＦＥディスパージョン１．５ｇを加え、さらにＨＦＣ４３−１０を３５０ｇ加えて３０ｒｐｍで１０分間撹拌し、スラリー状とした。
【００２３】
このスラリー状混合物をスパチュラーを用いて２０メッシュのスクリーンを通すことで成形造粒した。
【００２４】
得られた粗粒子をイオン交換水１．５Ｌ中に投入した後、４００ｒｐｍで３０分間、２５℃で撹拌し整粒した。その後撹拌しながら３０分かけて５０℃まで昇温させた。これを１５０メッシュの篩で水分離し、１７０℃で５時間乾燥し造粒粉末を得た。その評価結果を表１に示す。
【００２５】
［実施例２］
スラリー調製時にＰＴＦＥディスパージョンを加えず、またＨＦＣ４３−１０の代わりにＨＣＦＣ２２５ｃｂを使用した以外は実施例１と同様に造粒粉末を得、その評価を行った。結果を表１に示す。
【００２６】
［実施例３］
ＨＦＣ４３−１０の代わりにＨＣＦＣ２２５ｃｂを使用した以外は実施例１と同様に造粒粉末を得、その評価を行った。結果を表１に示す。
【００２７】
［比較例１］
内容積５０Ｌの撹拌機付き密閉容器に、懸濁重合から得られ粉砕された平均粒径３５μｍのＰＴＦＥ粉末３３５０ｇ、コークス粉末１５５０ｇ、グラファイト粉末１００ｇ計５０００ｇを計量し、ＰＣＥを２．７５ｋｇ加えた後、水２０Ｌを加え、７０℃に保ち、回転数１０００ｒｐｍ（周速度約１０ｍ／秒）で７分間撹拌してＰＴＦＥ粒子を凝集した後、回転数を３８０ｒｐｍに落とし、さらに１０分間撹拌しＰＴＦＥ凝集粉末を整粒した。これを１５０メッシュの篩で水分離し、１７０℃で５時間乾燥し造粒粉末を得た。その評価結果を表１に示す。
【００２８】
【表１】
【００２９】
［実施例４〜５］
３Ｌの造粒槽にＰＴＦＥ８５０ｇ、グラファイト粉末１５０ｇ計１０００ｇを計量し、さらにＨＦＣ４３−１０を１５００ｇ加えて３０ｒｐｍで１０分間撹拌し、スラリー状とした。
【００３０】
このスラリー状混合物をロール型造粒機（ダルトン社製ＰＶ−５）に投入し、目開き０．７ｍｍ（実施例４）と１．０ｍｍ（実施例５）のスクリーンから押出した。
【００３１】
得られた粗粒子をイオン交換水４．５Ｌ中に投入した後、４００ｒｐｍで３０分間、２５℃で撹拌し整粒した。その後撹拌しながら３０分かけて５０℃まで昇温させた。これを１５０メッシュの篩で水分離し、１７０℃で５時間乾燥し造粒粉末を得た。その評価結果を表２に示す。
【００３２】
［比較例２］
実施例４においてスクリーンから押出して得た粗粒子をダルトン社製マルメライザーに投入し、２５℃で１分間撹拌し、整粒した。その後１７０℃で５時間乾燥し、造粒粉末を得た。その評価結果を表２に示す。
【００３３】
［比較例３］
比較例１において、ＰＴＦＥ粒状粉末を４２５０ｇ、グラファイト粉末７５０ｇ計５０００ｇを使用した以外は比較例１と同様に操作し、造粒粉末を得た。その評価結果を表２に示す。
【００３４】
【表２】
【発明の効果】
本発明の造粒方法によって得られるＰＴＦＥ成形用粉末は、機械的な圧縮により所望の粒子径となるように粒状化されており、微粉が少なくまた粒度分布も狭い。また該造粒粉末から充填材が脱離し難く、成形までに種々の外力が加わっても造粒粉末が容易に崩壊することがないため、粉末流動性及び成形性が優れている。さらに見掛密度が大きく、小粒径で粒度分布の狭い造粒粉末を得ることが可能であるので、緻密な成形品を容易に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing PTFE molding powder with a filler having a small average particle size and a narrow particle size distribution by granulation from fine polytetrafluoroethylene (hereinafter referred to as PTFE) powder and a filler.
[0002]
[Prior art]
Since PTFE powder has poor fluidity even at temperatures above the melting point, a method of compression pre-molding / firing is employed when molding it. For this reason, the properties of the PTFE molding powder itself have a great influence on the moldability of the powder and the physical properties of the molded product obtained from the powder. Therefore, the properties required for PTFE molding powder are good powder flowability so that it can be easily filled into a mold, high apparent density so that compression pre-molding can be performed with as small a mold as possible, and pre-molding pressure as low as possible. Therefore, the primary particle size of the powder is required to be as small as possible so that a dense molded product can be obtained.
[0003]
As a method for obtaining such characteristics, conventionally, it has been proposed to finely pulverize PTFE coarse particles obtained by a suspension polymerization method, and then granulate them to form secondary particles. The main granulation method is a method in which the finely pulverized PTFE powder is added to a mixed liquid of an organic liquid insoluble or sparingly soluble in water and water and stirred at a temperature of 0 to 100 ° C. (Japanese Patent Publication No. 44). No. -22619) and a method of granulating by applying an organic liquid to the finely pulverized PTFE powder and subjecting the powder to rolling action and crushing action (Japanese Patent Publication No. 43-6290). Divided.
[0004]
However, since the former method uses an organic liquid such as trichlorotrifluoroethane as an organic liquid insoluble in water, there is a problem of environmental pollution, and in recent years, there is a tendency to avoid this method. Furthermore, this method has a problem that the filler is easily detached from the granulated powder. On the other hand, since the latter method allows the organic liquid to be selected relatively freely, it is possible to avoid environmental pollution problems caused by the chlorinated organic liquid, but the obtained granulated powder is obtained by the granulation obtained by the former method. There is a problem that the apparent density and powder flowability are lower than those of powder.
[0005]
In any of these methods, a filler-filled PTFE molding powder having a small average particle size and a narrow particle size distribution has not been obtained. In recent years, it is necessary to minimize cutting loss after molding due to environmental problems such as recycling, and it is required to mold with a mold as close to the final product as possible. Therefore, when it is necessary to mold with a molding die having a narrow slit width, the PTFE powder produced by the above method is sieved and only the powder having a small particle diameter is taken out and molded.
[0006]
[Problems to be solved by the invention]
Therefore, an object of the present invention is a method for producing a filled PTFE molding powder excellent in fluidity and moldability that can be directly used for molding by granulation without the need for such sieving. Is to provide. It is another object of the present invention to provide a method for producing a PTFE molding powder containing a filler which has no detachment of PTFE and filler, can easily control the particle size of the obtained powder, and has a narrow particle size distribution. It is in.
[0007]
[Means for Solving the Problems]
That is, according to the present invention, PTFE powder having an average particle size of 100 μm or less and a filler are stirred in decafluoropentane or dichloropentafluoropropane to form a slurry, which is molded and extruded as coarse particles having a particle size of 200 to 1000 μm. Furthermore, a method for producing a powder for molding PTFE is provided, which is sized by stirring in water.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The PTFE raw material powder used in the present invention has an average particle diameter of 100 μm or less, preferably 5 to 100 μm, particularly preferably 10 to 50 μm, and is generally tetrafluoroethylene (hereinafter referred to as TFE) obtained by suspension polymerization. It can be obtained by pulverizing a coarse powder of a homopolymer or a TFE copolymer copolymerized with 2% by weight or less, preferably 1% by weight or less of a monomer copolymerizable with TFE. A granulated powder obtained from a powder having an average particle size exceeding 100 μm is not preferable because it has poor powder flowability and apparent density and can easily form a molded product having many pores.
[0009]
Examples of the copolymerizable monomer in the TFE copolymer include perfluoroalkenes having 3 or more carbon atoms such as hexafluoropropylene, perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), and perfluoro (propyl). Perfluoro (alkyl vinyl ether) such as vinyl ether).
[0010]
The filler used in the present invention is not particularly limited, and any filler can be used as long as it is usually mixed with PTFE powder for molding. Specific examples include powders such as glass, carbon, graphite, alumina, mica, silicon carbide, boron nitride, titanium oxide, bronze, gold, silver, copper, nickel, stainless steel, molybdenum disulfide, and fibrous powders. be able to. The blending amount of the filler with respect to PTFE is preferably in the range of 5 to 40 parts by weight, particularly 15 to 25 parts by weight when the total amount of both is 100 parts by weight.
[0011]
In the present invention, the water-insoluble organic liquid used for stirring the PTFE powder and the filler to form a slurry is dichloropentafluoropropane or decafluoropentane. Of course, these may be used as a mixture of two or more, and when there are various isomers, they can be used alone or as a mixture.
[0012]
Among these water-insoluble organic liquids, those having a surface tension at 25 ° C. of 25 dynes / cm or less are preferred because the PTFE powder can be easily wetted, and hence can be easily mixed and granulated with the filler. Further, in order to minimize the volatilization of the organic liquid while passing through the granulator in a slurry state, it is desirable to select one having a boiling point of about 40 to 80 ° C., particularly about 50 to 60 ° C.
[0013]
In the present invention, a slurry is first formed by stirring the PTFE powder and the filler in the water-insoluble organic liquid. The amount of the water-insoluble organic liquid used at this time can be arbitrarily selected, but the range of about 100 to 200 parts by weight is optimal per 100 parts by weight of the total amount of PTFE powder and filler.
[0014]
When using a hydrophilic or semi-hydrophilic filler as the filler, use one that has been surface-treated with a surface treatment agent in order to impart affinity to PTFE, or add an affinity imparting agent during slurry formation. It is desirable to keep it. As the surface treating agent or affinity imparting agent that can be used for such a purpose, a compound having an alkoxysilane bond, particularly an alkoxysilane compound having an amino group is suitable. Specifically, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, aminophenyltriethoxy Examples include aminosilane such as silane, phenyltrimethoxysilane, phenyltriethoxysilane, p-chlorophenyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and phenylsilane such as diphenylsilanediol, and silicone oil. Also, PTFE dispersion can be used for such purposes, and is effective in preventing the detachment of the filler from the granulated powder.
[0015]
In the slurry formation, it is not necessary to heat in particular, and it may be performed near the atmospheric temperature. Moreover, it is not necessary to make the stirring speed particularly high, and although it varies depending on the apparatus, for example, about 10 to 100 rpm is sufficient, and the stirring time is about 10 minutes.
[0016]
In the present invention, if such a slurry is used to obtain coarse particles having a particle size of about 200 to 1000 μm by molding extrusion, and the slurry-like PTFE mixture is continuously or intermittently extruded, the method is used. There is no particular limitation. For example, a semi-dry roll type in which 2 to 4 rollers mounted radially rotate on a screen die (punched wire mesh) fixed while revolving by frictional resistance, and slurry is extruded from the hole of the screen die to the bottom. It can granulate using commercially available extrusion apparatuses, such as a granulator, a screw extrusion granulator, and a gear roll extrusion granulator. By appropriately selecting the size of the screen diameter, particles having a desired particle diameter can be obtained.
[0017]
The PTFE particles containing the water-insoluble organic liquid obtained in this way are then sized in water with stirring and transformed into a rounded shape that is easy to flow. The amount of water used is suitably in the range of about 100 to 500 parts by weight per 100 parts by weight of PTFE particles. The hardness, surface state, fluidity, and the like of the resulting granulated particles are slightly different depending on the temperature, time, stirring speed, and the like during granulation. These differ depending on the size and shape of the treatment tank or the type of the water-insoluble organic solvent used. For example, if stirring is performed at a temperature of about 10 to 70 ° C. and a temperature of 100 to 1000 rpm for about 10 to 180 minutes. Good. In general, it is preferable to first stir at a low temperature and gradually elevate the temperature to evaporate and remove the water-insoluble solvent.
[0018]
The PTFE granulated powder obtained by sizing and drying by the above method has a narrower particle size distribution than the PTFE granulated powder obtained by the conventional solid-liquid mixed granulation method, and has excellent fluidity and moldability. It is useful as a raw material for compression molding.
[0019]
【Example】
Hereinafter, the present invention will be specifically described by way of examples. In addition, the evaluation method of the raw material used in the Example and the comparative example and the obtained powder for PTFE shaping | molding is as follows.
[0020]
1 Raw material (a) PTFE raw material powder: Teflon 7-J (Mitsui / Dupont Fluoro Chemical Co., Ltd.)
(B) Filler coke powder: manufactured by Nippon Carbon Co., Ltd. (average particle size 21 μm)
Graphite powder: manufactured by Oriental Sangyo Co., Ltd. (average particle size 21 μm)
(C) Water-insoluble organic liquid 1,3-dichloro-1,1,2,2,3-pentafluoropropane: HCFC225cb (surface tension 16.7 dynes / cm at 25 ° C., boiling point 56 ° C.)
1,1,1,2,3,4,4,5,5,5-decafluoropentane: HFC43-10mee (surface tension 14.1 dynes / cm at 25 ° C., boiling point 55 ° C., Mitsui DuPont Fluorochemicals, Inc. Made)
Perchlorethylene: PCE (surface tension 32.3 dynes / cm at 20 ° C, boiling point 121.2 ° C)
(D) Affinity imparting agent silane coupling agent: KBM-603 (manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone oil: SH-200 manufactured by Shin-Etsu Chemical Co., Ltd.)
PTFE dispersion: solid content 30wt%
[0021]
2 Physical property evaluation method (a) Average particle diameter: Using an RPS-95 type manufactured by Seishin Enterprise Co., Ltd., in order from the top of the measurement, use 14, 16, 20, 28, 35, 48, 70, 100 mesh standard sieves in 8 layers. Then, the weight of the powder remaining on each sieve was determined, and the particle diameters of 16%, 50% and 84% by weight were determined on logarithmic probability paper based on the respective weights, and this was used as a criterion for determining whether the particle size distribution was wide or narrow. Also, the value of 100 mesh pass was examined and used as a measure of the proportion of fine powder.
(B) Apparent density: measured according to ASTM D-1457 (c) Tensile properties: Granulated powder was preformed at 600 kg / cm 2 and fired at 380 ° C. for 30 minutes to obtain a flat plate having a thickness of 2 mm. From this, test specimens were punched in accordance with ASTM D-638, and the elongation and tensile strength were measured.
(D) Shrinkage rate: A sample for measuring specific gravity was prepared according to ASTM D-1457, and the shrinkage rate was measured from the perimeter and the mold.
[0022]
[Example 1]
300 g total of PTFE 201 g, coke powder 93 g, graphite powder 6 g are weighed in a 3 L granulation tank, 0.127 g of silane coupling agent, 0.06 g of silicone oil and 1.5 g of PTFE dispersion are added to this, and further HFC43-10 350 g was added and stirred at 30 rpm for 10 minutes to form a slurry.
[0023]
This slurry mixture was shaped and granulated by passing it through a 20 mesh screen using a spatula.
[0024]
The obtained coarse particles were put into 1.5 L of ion-exchanged water, and then sized by stirring at 25 ° C. for 30 minutes at 400 rpm. Thereafter, the temperature was raised to 50 ° C. over 30 minutes with stirring. This was separated by water with a 150 mesh sieve and dried at 170 ° C. for 5 hours to obtain a granulated powder. The evaluation results are shown in Table 1.
[0025]
[Example 2]
A granulated powder was obtained and evaluated in the same manner as in Example 1 except that PTFE dispersion was not added during slurry preparation and HCFC225cb was used instead of HFC43-10. The results are shown in Table 1.
[0026]
[Example 3]
A granulated powder was obtained and evaluated in the same manner as in Example 1 except that HCFC225cb was used instead of HFC43-10. The results are shown in Table 1.
[0027]
[Comparative Example 1]
After a total of 5000 g of PTFE powder 3350 g, coke powder 1550 g and graphite powder 100 g, obtained by suspension polymerization and pulverized in a sealed container with a stirrer with an internal volume of 50 L, 2.75 kg of PCE was added. Add 20 L of water, keep at 70 ° C., stir for 7 minutes at a rotational speed of 1000 rpm (circumferential speed of about 10 m / second) to aggregate PTFE particles, then reduce the rotational speed to 380 rpm and stir for another 10 minutes to agglomerate PTFE powder Sized. This was separated by water with a 150 mesh sieve and dried at 170 ° C. for 5 hours to obtain a granulated powder. The evaluation results are shown in Table 1.
[0028]
[Table 1]
[Examples 4 to 5]
In a 3 L granulation tank, PTFE 850 g and graphite powder 150 g total 1000 g were weighed, and further 1500 g of HFC43-10 was added and stirred at 30 rpm for 10 minutes to form a slurry.
[0030]
This slurry-like mixture was put into a roll type granulator (PV-5 manufactured by Dalton Co.) and extruded from a screen having openings of 0.7 mm (Example 4) and 1.0 mm (Example 5).
[0031]
The obtained coarse particles were put into 4.5 L of ion-exchanged water, and then sized by stirring at 25 ° C. for 30 minutes at 400 rpm. Thereafter, the temperature was raised to 50 ° C. over 30 minutes with stirring. This was separated by water with a 150 mesh sieve and dried at 170 ° C. for 5 hours to obtain a granulated powder. The evaluation results are shown in Table 2.
[0032]
[Comparative Example 2]
The coarse particles obtained by extrusion from the screen in Example 4 were put into a Dalton Malmerizer and stirred at 25 ° C. for 1 minute for sizing. Then, it dried at 170 degreeC for 5 hours, and obtained the granulated powder. The evaluation results are shown in Table 2.
[0033]
[Comparative Example 3]
In Comparative Example 1, granulated powder was obtained in the same manner as in Comparative Example 1, except that 4250 g of PTFE granular powder and 750 g of graphite powder were used in total, 5000 g. The evaluation results are shown in Table 2.
[0034]
[Table 2]
【The invention's effect】
The PTFE molding powder obtained by the granulation method of the present invention is granulated so as to have a desired particle diameter by mechanical compression, has a small amount of fine powder, and has a narrow particle size distribution. In addition, the filler is not easily detached from the granulated powder, and the granulated powder is not easily disintegrated even when various external forces are applied before molding, so that the powder flowability and moldability are excellent. Furthermore, since it is possible to obtain a granulated powder having a large apparent density, a small particle size and a narrow particle size distribution, a dense molded product can be easily produced.
Claims (2)
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| JP2000398811A JP4698022B2 (en) | 2000-12-27 | 2000-12-27 | Method for producing filled polytetrafluoroethylene molding powder |
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| JP2000398811A JP4698022B2 (en) | 2000-12-27 | 2000-12-27 | Method for producing filled polytetrafluoroethylene molding powder |
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| JP4698022B2 true JP4698022B2 (en) | 2011-06-08 |
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| JP4222053B2 (en) * | 2003-02-20 | 2009-02-12 | 旭硝子株式会社 | Polytetrafluoroethylene composition, granulated product and molded product |
| WO2009022400A1 (en) * | 2007-08-10 | 2009-02-19 | Nippon Fusso Co., Ltd | Fluororesin composite material, linings made from the composite material and articles with the linings |
| JP2023108326A (en) | 2022-01-25 | 2023-08-04 | 三井・ケマーズ フロロプロダクツ株式会社 | Polytetrafluoroethylene granulated powder and method for producing the same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5228552A (en) * | 1975-08-29 | 1977-03-03 | Asahi Glass Co Ltd | Process for producing pulverized polytetrafluoroethylene powder |
| JPS63286435A (en) * | 1987-05-19 | 1988-11-24 | Central Glass Co Ltd | Fluorine-containing resin dispersion |
| JPH1192569A (en) * | 1997-07-24 | 1999-04-06 | Asahi Glass Co Ltd | Production of granulated polytetrafluoroethylene powder |
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- 2000-12-27 JP JP2000398811A patent/JP4698022B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5228552A (en) * | 1975-08-29 | 1977-03-03 | Asahi Glass Co Ltd | Process for producing pulverized polytetrafluoroethylene powder |
| JPS63286435A (en) * | 1987-05-19 | 1988-11-24 | Central Glass Co Ltd | Fluorine-containing resin dispersion |
| JPH1192569A (en) * | 1997-07-24 | 1999-04-06 | Asahi Glass Co Ltd | Production of granulated polytetrafluoroethylene powder |
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