JP5691160B2 - Method for producing polytetrafluoroethylene granulated powder - Google Patents
Method for producing polytetrafluoroethylene granulated powder Download PDFInfo
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- JP5691160B2 JP5691160B2 JP2009263508A JP2009263508A JP5691160B2 JP 5691160 B2 JP5691160 B2 JP 5691160B2 JP 2009263508 A JP2009263508 A JP 2009263508A JP 2009263508 A JP2009263508 A JP 2009263508A JP 5691160 B2 JP5691160 B2 JP 5691160B2
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- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims description 142
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims description 142
- 239000000843 powder Substances 0.000 title claims description 126
- 238000004519 manufacturing process Methods 0.000 title claims description 20
- -1 polytetrafluoroethylene Polymers 0.000 title claims description 15
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 30
- 238000009835 boiling Methods 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- 239000007788 liquid Substances 0.000 claims description 17
- 125000004432 carbon atom Chemical group C* 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 7
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 6
- 125000003709 fluoroalkyl group Chemical group 0.000 claims 2
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 claims 2
- 238000005469 granulation Methods 0.000 description 14
- 230000003179 granulation Effects 0.000 description 14
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 6
- 230000001771 impaired effect Effects 0.000 description 6
- 238000010792 warming Methods 0.000 description 6
- 238000001246 colloidal dispersion Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000000945 filler Substances 0.000 description 4
- 125000001153 fluoro group Chemical group F* 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 150000005215 alkyl ethers Chemical class 0.000 description 3
- 239000008187 granular material Substances 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000008282 halocarbons Chemical class 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 125000005010 perfluoroalkyl group Chemical group 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- OKIYQFLILPKULA-UHFFFAOYSA-N 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane Chemical compound COC(F)(F)C(F)(F)C(F)(F)C(F)(F)F OKIYQFLILPKULA-UHFFFAOYSA-N 0.000 description 1
- KHXKESCWFMPTFT-UHFFFAOYSA-N 1,1,1,2,2,3,3-heptafluoro-3-(1,2,2-trifluoroethenoxy)propane Chemical compound FC(F)=C(F)OC(F)(F)C(F)(F)C(F)(F)F KHXKESCWFMPTFT-UHFFFAOYSA-N 0.000 description 1
- 229910000906 Bronze Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 241000238366 Cephalopoda Species 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 229920006015 heat resistant resin Polymers 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
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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- Processes Of Treating Macromolecular Substances (AREA)
Description
本発明は、引張強度や伸度等の特性に優れる成形品を得ることが可能なポリテトラフルオロエチレン造粒粉末の製造方法に関する。 The present invention relates to a method for producing a polytetrafluoroethylene granulated powder capable of obtaining a molded product having excellent properties such as tensile strength and elongation.
ポリテトラフルオロエチレン（以下、「ＰＴＦＥ」という）は、熱可塑性樹脂とは異なり溶融成形できないため、粉末の形のままで成形に供される。このため、ＰＴＦＥの成形に供される粉末には特別の粉体特性が要求される。要求される粉末特性としては、流動性が良いこと、かさ密度が大きいこと、脆すぎず壊れにくいことなどが挙げられる。 Since polytetrafluoroethylene (hereinafter referred to as “PTFE”) cannot be melt-molded unlike a thermoplastic resin, it is used for molding in the form of a powder. For this reason, special powder characteristics are required for the powder used for the molding of PTFE. The required powder characteristics include good fluidity, a large bulk density, and being not too brittle and not easily broken.
テトラフルオロエチレン（以下、「ＴＦＥ」という）を懸濁重合して得られるＰＴＦＥの粒状固体を微粉砕したＰＴＦＥの一次粉末（以下、「ＰＴＦＥ粉末」という）は、平均粒径が２００μｍ以下であり、また、上記粉体特性を有していない。このため、ＰＴＦＥ粉末を造粒して、上記粉体特性を有するＰＴＦＥ造粒粉末が製造される。 PTFE primary powder (hereinafter referred to as “PTFE powder”) obtained by finely pulverizing a PTFE granular solid obtained by suspension polymerization of tetrafluoroethylene (hereinafter referred to as “TFE”) has an average particle size of 200 μm or less. Also, it does not have the above powder characteristics. Therefore, PTFE powder is granulated to produce PTFE granulated powder having the above powder characteristics.
ＰＴＦＥ粉末の造粒方法としては、ＰＴＦＥ粉末を、水と有機媒体とからなる２相液体媒質中で攪拌してＰＴＦＥ粉末を凝集し、造粒する方法が主に行われている。 As a method for granulating PTFE powder, a method of agglomerating and granulating PTFE powder by stirring PTFE powder in a two-phase liquid medium composed of water and an organic medium is mainly performed.
有機媒体としては、従来よりハロゲン化炭化水素（特許文献１）や、ヒドロフルオロカーボン（特許文献２）等が使用されている。しかしながら、ハロゲン化炭化水素はオゾン破壊係数が大きいため、２０２０年で使用が禁止される。ヒドロフルオロカーボンは地球温暖化係数が大きい。そこで、近年においては、オゾン破壊係数が零で、かつ、地球温暖化係数の小さい有機媒体を用いる試みがなされている。 As organic media, halogenated hydrocarbons (Patent Document 1), hydrofluorocarbons (Patent Document 2), and the like have been used. However, since halogenated hydrocarbons have a large ozone depletion coefficient, their use is prohibited in 2020. Hydrofluorocarbons have a large global warming potential. Therefore, in recent years, an attempt has been made to use an organic medium having a zero ozone depletion coefficient and a small global warming coefficient.
下記特許文献３には、平均粒径２００μｍ以下のＰＴＦＥ粉末を、水とＲ−Ｏ−Ｒ’（式中、Ｒは炭素数２〜６のポリフルオロアルキル基であり、Ｒ’は炭素数１または２のアルキル基である）で表される（ポリフルオロアルキル）アルキルエーテルとからなる２相液体媒質中で攪拌、造粒してＰＴＦＥ造粒粉末を製造することが開示されている。 In the following Patent Document 3, PTFE powder having an average particle size of 200 μm or less is mixed with water and R—O—R ′ (wherein R is a polyfluoroalkyl group having 2 to 6 carbon atoms, and R ′ is 1 carbon atom). Alternatively, it is disclosed that PTFE granulated powder is produced by stirring and granulating in a two-phase liquid medium composed of (polyfluoroalkyl) alkyl ether represented by (which is an alkyl group of 2).
しかしながら、特許文献３の方法で使用される（ポリフルオロアルキル）アルキルエーテルは、オゾン破壊係数が零で、かつ、地球温暖化係数が小さいが、得られるＰＴＦＥ造粒粉末は、得られる成形品の引張り強度や伸度等の物性が十分ではなかった。 However, the (polyfluoroalkyl) alkyl ether used in the method of Patent Document 3 has a zero ozone depletion coefficient and a small global warming coefficient. However, the obtained PTFE granulated powder is obtained from the molded product obtained. Physical properties such as tensile strength and elongation were not sufficient.
したがって、本発明の目的は、オゾン層破壊係数が零で、地球温暖化係数の小さい有機媒体を使用して、引張り強度や伸度等に優れた成形品を得ることが可能なＰＴＦＥ造粒粉末の製造方法を提供することにある。 Accordingly, an object of the present invention is to provide a PTFE granulated powder that can obtain a molded product excellent in tensile strength, elongation, etc., using an organic medium having a zero ozone layer depletion coefficient and a small global warming coefficient. It is in providing the manufacturing method of.
本発明は、以下を提供する。
［１］ 平均粒径２００μｍ以下のＰＴＦＥ粉末を、水と下式（１）で表されるヒドロフルオロアルキルエーテルとからなる２相液体媒質中で攪拌して造粒することを特徴とする、ＰＴＦＥ造粒粉末の製造方法。
Ｒ１−Ｏ−Ｒ２ ・・・（１）
（式（１）中、Ｒ１及びＲ２はポリフルオロアルキル基であり、Ｒ１及びＲ２の少なくとも一方は水素原子を有し、Ｒ１とＲ２の合計の炭素原子数は３〜８である。）
［２］ 前記ヒドロフルオロアルキルエーテルの沸点が２５〜６０℃である、［１］に記載のＰＴＦＥ造粒粉末の製造方法。
［３］ 前記ヒドロフルオロアルキルエーテルが、ＣＦ３ＣＨ２ＯＣＦ２ＣＨＦ２及びＣＦ３ＣＦ２ＣＨ２ＯＣＨＦ２からなる群から選ばれる１種以上である、［１］又は［２］に記載のＰＴＦＥ造粒粉末の製造方法。
［４］ 前記２相液体媒質は、前記ＰＴＦＥ粉末の１質量部に対し、前記水の１〜４０質量部、前記ヒドロフルオロアルキルエーテルの０．１〜３質量部、を含むものである、［１］〜［３］のいずれかに記載のＰＴＦＥ造粒粉末の製造方法。
［５］ 前記ＰＴＦＥ粉末を、前記２相液体媒質中にて、１０℃〜前記ヒドロフルオロアルキルエーテルの沸点以下の温度範囲で攪拌し、最終的に前記ヒドロフルオロアルキルエーテルの沸点まで昇温して前記ヒドロフルオロアルキルエーテルを蒸発させ、除去する、［１］〜［４］のいずれかに記載のＰＴＦＥ造粒粉末の製造方法。
［６］ ＰＴＦＥ粉末の造粒物を分別し、乾燥する、［１］〜［５］のいずれかに記載のＰＴＦＥ造粒粉末の製造方法。
The present invention provides the following.
[1] A PTFE powder having an average particle size of 200 μm or less is stirred and granulated in a two-phase liquid medium composed of water and a hydrofluoroalkyl ether represented by the following formula (1). A method for producing granulated powder.
R 1 —O—R 2 (1)
(In the formula (1), R 1 and R 2 are polyfluoroalkyl group, at least one of R 1 and R 2 are a hydrogen atom, R 1 and the total number of carbon atoms in R 2 is 3-8 .)
[2] The method for producing a PTFE granulated powder according to [1], wherein the hydrofluoroalkyl ether has a boiling point of 25 to 60 ° C.
[3] The PTFE according to [1] or [2], wherein the hydrofluoroalkyl ether is one or more selected from the group consisting of CF 3 CH 2 OCF 2 CHF 2 and CF 3 CF 2 CH 2 OCHF 2. A method for producing granulated powder.
[4] The two-phase liquid medium contains 1 to 40 parts by mass of the water and 0.1 to 3 parts by mass of the hydrofluoroalkyl ether with respect to 1 part by mass of the PTFE powder. [1] The manufacturing method of the PTFE granulated powder in any one of-[3].
[5] The PTFE powder is stirred in the two-phase liquid medium in a temperature range of 10 ° C. to the boiling point of the hydrofluoroalkyl ether, and finally heated to the boiling point of the hydrofluoroalkyl ether. The method for producing a PTFE granulated powder according to any one of [1] to [4], wherein the hydrofluoroalkyl ether is evaporated and removed.
[6] The method for producing PTFE granulated powder according to any one of [1] to [5], wherein the granulated product of PTFE powder is separated and dried.
本発明のＰＴＦＥ造粒粉末の製造方法によれば、引張り強度や伸度等に優れた成形品を得ることが可能なＰＴＦＥ造粒粉末を製造できる。また、上式（１）で表されるヒドロフルオロアルキルエーテルは、オゾン破壊係数が零であり、地球温暖化係数が小さいので、環境負荷が極めて小さい。 According to the method for producing a PTFE granulated powder of the present invention, a PTFE granulated powder capable of obtaining a molded product excellent in tensile strength, elongation and the like can be produced. In addition, the hydrofluoroalkyl ether represented by the above formula (1) has an ozone depletion coefficient of zero and a low global warming coefficient, and therefore has an extremely low environmental load.
本発明のＰＴＦＥ造粒粉末の製造方法は、平均粒径２００μｍ以下のＰＴＦＥ粉末を、水と下式（１）で表されるヒドロフルオロアルキルエーテル（以下、「ＨＦＥ」という）とからなる２相液体媒質中で攪拌して造粒する。
Ｒ１−Ｏ−Ｒ２ ・・・（１）
（式（１）中、Ｒ１及びＲ２はポリフルオロアルキル基であり、Ｒ１及びＲ２の少なくとも一方は水素原子を有し、Ｒ１とＲ２の合計の炭素原子数は３〜８である。）
The method for producing PTFE granulated powder of the present invention comprises a PTFE powder having an average particle size of 200 μm or less and two phases comprising water and a hydrofluoroalkyl ether represented by the following formula (1) (hereinafter referred to as “HFE”). Agitate in a liquid medium and granulate.
R 1 —O—R 2 (1)
(In the formula (1), R 1 and R 2 are polyfluoroalkyl group, at least one of R 1 and R 2 are a hydrogen atom, R 1 and the total number of carbon atoms in R 2 is 3-8 .)
本発明のＰＴＦＥ造粒粉末の製造方法で使用するＰＴＦＥ粉末は、平均粒径２００μｍ以下のものである。このようなＰＴＦＥ粉末としては、例えば、ＴＦＥを懸濁重合して得られるＰＴＦＥの粒状固体を、平均粒径２００μｍ以下の一次粉末に微粉砕したものが挙げられる。ＰＴＦＥ粉末の平均粒径は、１０〜７０μｍが好ましく、１５〜６０μｍがより好ましい。ＰＴＦＥ粉末の平均粒径が２００μｍを超えると、かさ密度の小さいＰＴＦＥ造粒粉末になり易い。更には、ＰＴＦＥ造粒粉末中に空隙が残り易く、均一性が損なわれ易い。ＰＴＦＥ粉末の平均粒径が１０μｍ未満であると、ＰＴＦＥ粉末の造粒性の低下や、ＰＴＦＥ成形品の引張強度や伸度が低下する傾向となる。本発明において、平均粒径が２００μｍ以下のＰＴＦＥ粉末の平均粒径はレーザー式粒径測定器で測定した値である。 The PTFE powder used in the method for producing a PTFE granulated powder of the present invention has an average particle size of 200 μm or less. Examples of such PTFE powder include a powder obtained by pulverizing a PTFE granular solid obtained by suspension polymerization of TFE into a primary powder having an average particle size of 200 μm or less. 10-70 micrometers is preferable and, as for the average particle diameter of PTFE powder, 15-60 micrometers is more preferable. When the average particle size of the PTFE powder exceeds 200 μm, it becomes easy to obtain a PTFE granulated powder having a small bulk density. Furthermore, voids are likely to remain in the PTFE granulated powder, and uniformity is likely to be impaired. When the average particle size of the PTFE powder is less than 10 μm, the granulation property of the PTFE powder is lowered, and the tensile strength and elongation of the PTFE molded product tend to be lowered. In the present invention, the average particle size of PTFE powder having an average particle size of 200 μm or less is a value measured by a laser particle size measuring instrument.
ＰＴＦＥ粉末は、未焼成であることが好ましい。未焼成のＰＴＦＥ粉末は造粒に適しているので、造粒に要する時間を低減できる。本発明において未焼成とは、ＴＦＥの重合後、その融点以上に加熱されていない状態の粉末を意味する。 The PTFE powder is preferably unfired. Since the unsintered PTFE powder is suitable for granulation, the time required for granulation can be reduced. In the present invention, unsintered means a powder that has not been heated above its melting point after polymerization of TFE.
なお、本発明において、ＰＴＦＥとしては、ＴＦＥの単独重合体に加えて、実質的に溶融加工性を付与しない程度の微量、好ましくは２質量％以下の割合でＴＦＥと共重合しうるコモノマーに基づく重合単位を含むＰＴＦＥである、いわゆる変性ＰＴＦＥを含むものとする。該コモノマーとしては、ヘキサフルオロプロピレン等の炭素数３〜６のペルフルオロアルケン、ペルフルオロ（プロピルビニルエーテル）等の炭素数３〜６のペルフルオロ（アルキルビニルエーテル）等が挙げられる。 In the present invention, PTFE is based on a comonomer that can be copolymerized with TFE in a minute amount that does not substantially impart melt processability, preferably 2 mass% or less, in addition to a TFE homopolymer. It is assumed that so-called modified PTFE, which is PTFE containing polymerized units, is included. Examples of the comonomer include C3-C6 perfluoroalkene such as hexafluoropropylene, C3-C6 perfluoro (alkyl vinyl ether) such as perfluoro (propyl vinyl ether), and the like.
本発明のＰＴＦＥ造粒粉末の製造方法では、水とＨＦＥとからなる２相液体媒質を用いる。 In the method for producing PTFE granulated powder of the present invention, a two-phase liquid medium composed of water and HFE is used.
ＨＦＥは、オゾン破壊係数が零であり、更には地球温暖化係数が小さいので、環境負荷が極めて小さい。また表面張力が小さく、水不溶性の有機媒体である。ＨＦＥのみを媒体として用い、ＰＴＦＥ粉末の造粒を行った場合、得られるＰＴＦＥ造粒粉末の内部が固くしまった状態になり、引張り強度や伸度等に優れた成形品が得られ難い。また、ＨＦＥの代わりに有機媒体として特許第３６６６２１０号公報に記載されている、（ポリフルオロアルキル）アルキルエーテル（以下、「ＰＦＡＥ」という）を用いて、水とＰＦＡＥとの２相液体媒質中でＰＴＦＥ粉末を造粒しても、後述する実施例（比較例）の例２及び３に示すように、引張り強度や伸度等に優れた成形品が得られ難い。これに対し、水とＨＦＥとからなる２相液体媒質中でＰＴＦＥ粉末を造粒することにより、引張り強度や伸度等に優れた成形品を得ることが可能なＰＴＦＥ造粒粉末を製造できる。この理由は、必ずしも明らかではないが、ＨＦＥの方がＰＦＡＥよりも比熱が大きく、蒸発潜熱も大きいことから、湿潤状態のＰＴＦＥ粉末の造粒物（以下、「ＰＴＦＥ造粒物」という）と有機媒体との分別が穏やかに進行すると考えられる。そのため、水とＨＦＥとからなる２相液体媒質中でＰＴＦＥ粉末を攪拌し、造粒することにより、ＰＴＦＥ粉末が適度に湿潤し、ＰＴＦＥ粉末の凝集が過度に進まず、適度に軟らかく、内部は均一で空隙が少なく、かさ密度が大きく、表面が平滑で流動性のよいＰＴＦＥ造粒粉末が得られると考えられる。 HFE has a very low environmental impact because it has a zero ozone depletion coefficient and a low global warming coefficient. In addition, it is a water-insoluble organic medium with low surface tension. When PTFE powder is granulated using only HFE as a medium, the inside of the obtained PTFE granulated powder is in a hardened state, and it is difficult to obtain a molded product excellent in tensile strength, elongation and the like. In addition, in the two-phase liquid medium of water and PFAE, (polyfluoroalkyl) alkyl ether (hereinafter referred to as “PFAE”) described in Japanese Patent No. 3666210 as an organic medium instead of HFE is used. Even if the PTFE powder is granulated, as shown in Examples 2 and 3 of Examples (Comparative Examples) described later, it is difficult to obtain a molded product excellent in tensile strength, elongation, and the like. On the other hand, by granulating PTFE powder in a two-phase liquid medium composed of water and HFE, a PTFE granulated powder capable of obtaining a molded product excellent in tensile strength, elongation and the like can be produced. The reason for this is not necessarily clear, but because HFE has a larger specific heat and larger latent heat of vaporization than PFAE, granulation of wet PTFE powder (hereinafter referred to as “PTFE granulation”) and organic It is thought that separation from the medium will proceed gently. Therefore, by stirring and granulating the PTFE powder in a two-phase liquid medium consisting of water and HFE, the PTFE powder is moderately wetted, the PTFE powder is not excessively agglomerated, and is moderately soft. It is considered that a PTFE granulated powder that is uniform, has few voids, has a large bulk density, has a smooth surface, and good fluidity can be obtained.
ＨＦＥは、上式（１）のＲ１及びＲ２が、直鎖状又は分岐状のヒドロフルオロアルキル基又はペルフルオロアルキル基が好ましい。また、Ｒ１とＲ２は同一又は異なるポリフルオロアルキル基であってよい。Ｒ１とＲ２が有するフッ素原子の合計数は、水素原子の合計数よりも多いことが好ましい。Ｒ１及びＲ２が有するフッ素原子の割合は、水素原子とフッ素原子の合計数に対して６０％以上が好ましく、６５％以上がより好ましい。Ｒ１及びＲ２が有するフッ素原子の割合が少なすぎると、ＰＴＦＥ造粒粉末が固くなりやすい傾向となる。Ｒ１とＲ２の合計の炭素原子数は、３〜８個であり、４〜６個が好ましい。Ｒ１とＲ２の合計の炭素原子数が少なすぎると、ＨＦＥの沸点が低くなり、造粒に用いる有機媒体としての取り扱い性が損なわれ易い。また、得られるＰＴＦＥ造粒粉末は、かさ密度が小さく、流動性の悪いＰＴＦＥ造粒粉末となる傾向となる。Ｒ１とＲ２の合計の炭素原子数が多すぎると、ＨＦＥの沸点が高くなり、造粒媒体からＰＴＦＥ造粒物を分別することが困難になる。更には、得られるＰＴＦＥ造粒粉末が固くなり易く、成形品の引張強度、伸度が損なわれ易い。 In HFE, R 1 and R 2 in the above formula (1) are preferably a linear or branched hydrofluoroalkyl group or a perfluoroalkyl group. R 1 and R 2 may be the same or different polyfluoroalkyl groups. The total number of fluorine atoms contained in R 1 and R 2 is preferably larger than the total number of hydrogen atoms. The proportion of fluorine atoms to which R 1 and R 2 has preferably 60% or more relative to the total number of hydrogen atoms and fluorine atoms, and more preferably 65% or more. If the proportion of fluorine atoms in R 1 and R 2 is too small, the PTFE granulated powder tends to become hard. The total number of carbon atoms of R 1 and R 2 is 3-8, preferably 4-6. If the total number of carbon atoms of R 1 and R 2 is too small, the boiling point of HFE will be low, and the handleability as an organic medium used for granulation tends to be impaired. Moreover, the obtained PTFE granulated powder tends to be a PTFE granulated powder having a low bulk density and poor fluidity. When the total number of carbon atoms of R 1 and R 2 is too large, the boiling point of HFE increases and it becomes difficult to separate the PTFE granulated product from the granulation medium. Furthermore, the obtained PTFE granulated powder tends to be hard, and the tensile strength and elongation of the molded product are likely to be impaired.
ＨＦＥの沸点は、２５〜６０℃が好ましく、４０〜６０℃がより好ましく、４５〜６０℃が最も好ましい。ＨＦＥの沸点が高すぎると、ＰＴＦＥ造粒物からＨＦＥを除去する際に温度を高める必要がある。その結果、ＰＴＦＥ造粒物の内部が固くしまり、成形品の引張強度、伸度が損なわれ易い。ＨＦＥの沸点が低すぎると、ＰＴＦＥ粉末の凝集が不完全になり易く、得られるＰＴＦＥ造粒粉末は、小さい外力で壊れ易くなる傾向にある。 The boiling point of HFE is preferably 25 to 60 ° C, more preferably 40 to 60 ° C, and most preferably 45 to 60 ° C. If the boiling point of HFE is too high, it is necessary to increase the temperature when removing HFE from the PTFE granulated product. As a result, the inside of the PTFE granulated product is hardened, and the tensile strength and elongation of the molded product are easily impaired. When the boiling point of HFE is too low, the PTFE powder tends to be incompletely aggregated, and the resulting PTFE granulated powder tends to be easily broken by a small external force.
ＨＦＥは、好ましくは、下式（２）で表わされる化合物である。
Ｒ１ａ−ＣＨ２−Ｏ−Ｒ２ａ ・・・（２）
（式（２）中、Ｒ１ａ及びＲ２ｂは、水素原子を有しても良いポリフルオロアルキル基であり、Ｒ１ａとＲ２ｂの合計の炭素原子数は２〜７である。）
HFE is preferably a compound represented by the following formula (2).
R 1a —CH 2 —O—R 2a (2)
(In Formula (2), R 1a and R 2b are polyfluoroalkyl groups which may have a hydrogen atom, and the total number of carbon atoms of R 1a and R 2b is 2-7.)
（２）において、Ｒ１ａは、直鎖状又は分岐状のヒドロフルオロアルキル基又はペルフルオロアルキル基が好ましい。Ｒ２ａは、直鎖状又は分岐状のヒドロフルオロアルキル基が好ましい。 In (2), R 1a is preferably a linear or branched hydrofluoroalkyl group or a perfluoroalkyl group. R 2a is preferably a linear or branched hydrofluoroalkyl group.
ＨＦＥの好ましい具体例としては、ＣＦ３ＣＨ２ＯＣＦ２ＣＨＦ２（沸点５６℃）、ＣＦ３ＣＦ２ＣＨ２ＯＣＨＦ２（沸点４６℃）等が挙げられる。 Preferable specific examples of HFE include CF 3 CH 2 OCF 2 CHF 2 (boiling point 56 ° C.), CF 3 CF 2 CH 2 OCHF 2 (boiling point 46 ° C.), and the like.
本発明のＰＴＦＥ造粒粉末の製造方法で使用する上記２相液体媒質は、ＰＴＦＥ粉末の１質量部に対し、水の１〜４０質量部、ＨＦＥの０．１〜３質量部、を含むことが好ましく、水の２〜３０質量部、ＨＦＥの０．２〜２質量部、を含むことがより好ましく、水の２〜２０質量部、ＨＦＥの０．２〜１．５質量部、を含むことが最も好ましい。ＰＴＦＥ粉末に対する２相液体媒質中のＨＦＥの割合がこの範囲より多いと、ＰＴＦＥ造粒粉末の平均粒径が大きくなる傾向にあり、ＨＦＥの割合がこの範囲より少ないと、ＰＴＦＥ造粒粉末の平均粒径が小さくなる傾向にある。ＰＴＦＥ造粒粉末に対し、水とＨＦＥとをそれぞれ上記割合で含む２相液体媒質を用いることにより、引張り強度や伸度等に優れた成形品を得ることが可能な、適度な粒径のＰＴＦＥ造粒粉末が得られ易くなる。 The said two-phase liquid medium used with the manufacturing method of the PTFE granulated powder of this invention contains 1-40 mass parts of water and 0.1-3 mass parts of HFE with respect to 1 mass part of PTFE powder. It is more preferable to contain 2 to 30 parts by mass of water and 0.2 to 2 parts by mass of HFE, and 2 to 20 parts by mass of water and 0.2 to 1.5 parts by mass of HFE are included. Most preferred. When the ratio of HFE in the two-phase liquid medium to the PTFE powder is larger than this range, the average particle diameter of the PTFE granulated powder tends to increase. When the ratio of HFE is smaller than this range, the average of the PTFE granulated powder is increased. The particle size tends to be small. By using a two-phase liquid medium containing water and HFE in the above proportions with respect to the PTFE granulated powder, it is possible to obtain a molded product having an excellent tensile strength, elongation and the like. Granulated powder is easily obtained.
また、水の使用量は特に限定されないが、ＨＦＥとＰＴＦＥ粉末との総容量に対して２０〜１５００容量％が好ましく、５０〜１１００容量％がより好ましい。 Moreover, although the usage-amount of water is not specifically limited, 20-1500 volume% is preferable with respect to the total capacity | capacitance of HFE and PTFE powder, and 50-1100 volume% is more preferable.
ＰＴＦＥ粉末の造粒は、攪拌翼を備えた造粒装置などに、ＰＴＦＥ粉末、水、ＨＦＥを加え、攪拌することによって行う。造粒装置としては、通常の攪拌槽、邪魔板付き攪拌槽等を使用できる。攪拌翼としては、タービン翼、イカリ型翼等の通常使用される攪拌翼が使用できる。 The PTFE powder is granulated by adding PTFE powder, water and HFE to a granulator equipped with a stirring blade and stirring. As a granulator, a normal stirring tank, a stirring tank with a baffle plate, etc. can be used. As the stirring blades, commonly used stirring blades such as turbine blades and squid type blades can be used.
攪拌温度は、１０℃〜ＨＦＥの沸点以下の温度範囲が好ましく、２０℃〜ＨＦＥの沸点以下の温度範囲がより好ましく、２５℃〜ＨＦＥの沸点以下の温度範囲が最も好ましい。１０℃未満の温度下で攪拌を行っても、ＰＴＦＥ粉末が十分に軟化しないので、ＰＴＦＥ粉末が凝集し難く、造粒に時間を要する。ＨＦＥの沸点よりも高い温度下で攪拌すると、ＰＴＦＥ造粒物の内部が固くしまり、成形品の引張強度、伸度が損なわれ易い。 The stirring temperature is preferably a temperature range of 10 ° C. to the boiling point of HFE, more preferably a temperature range of 20 ° C. to the boiling point of HFE, and most preferably a temperature range of 25 ° C. to the boiling point of HFE. Even if stirring is performed at a temperature of less than 10 ° C., the PTFE powder is not sufficiently softened, so that the PTFE powder hardly aggregates and takes time for granulation. When stirring is performed at a temperature higher than the boiling point of HFE, the inside of the PTFE granulated product becomes hard, and the tensile strength and elongation of the molded product are easily impaired.
なお、ＰＴＦＥ造粒物は、ＨＦＥを含んでいるので、最終的にＨＦＥの沸点まで昇温してＰＴＦＥ造粒物が含んでいるＨＦＥを蒸発させ、除去して、ＰＴＦＥ造粒粉末を得ることが好ましい。ＰＴＦＥ粉末の造粒は、１０℃以上で、かつ、ＨＦＥの沸点よりも１０℃以上低い温度で攪拌を開始し、次第に温度を高めて、最終的にＨＦＥの沸点まで昇温してＨＦＥを蒸発させ、除去することが好ましい。ＨＦＥを蒸発させる際にＰＴＦＥ造粒物の内部が適度にしまり、適度な強度のＰＴＦＥ造粒粉末が得られる。ＨＦＥの沸点まで昇温するには、連続的に昇温してもよく、段階的に昇温してもよい。また、ＰＴＦＥ造粒物から蒸発させたＨＦＥは、別工程で回収して再利用することが好ましい。 Since PTFE granulated product contains HFE, the temperature is finally raised to the boiling point of HFE to evaporate and remove the HFE contained in the PTFE granulated product to obtain PTFE granulated powder. Is preferred. The granulation of PTFE powder starts stirring at a temperature of 10 ° C. or higher and lower than the boiling point of HFE by 10 ° C. or higher, gradually raises the temperature, and finally raises the temperature to the boiling point of HFE to evaporate HFE. It is preferable to remove them. When the HFE is evaporated, the inside of the PTFE granulated product becomes moderate, and a PTFE granulated powder having an appropriate strength is obtained. In order to raise the temperature to the boiling point of HFE, the temperature may be raised continuously or in steps. Moreover, it is preferable to collect | recover and reuse HFE evaporated from PTFE granulated material by another process.
攪拌時間は、１分〜１０時間が好ましく、３分〜５時間がより好ましく、５分〜３時間が最も好ましい。 The stirring time is preferably 1 minute to 10 hours, more preferably 3 minutes to 5 hours, and most preferably 5 minutes to 3 hours.
攪拌速度は、攪拌翼の周速度として０．５〜１００ｍ／秒が好ましく、１〜５０ｍ／秒がより好ましく、２〜５０ｍ／秒が最も好ましい。攪拌翼の周速度が速いと、ＰＴＦＥ粉末が強固に凝集し易いので、得られるＰＴＦＥ造粒粉末は内部が固くしまり、かさ密度が大きくなる傾向にある。攪拌翼の周速度が遅いと、ＰＴＦＥ粉末の凝集が不十分になり易いので、得られるＰＴＦＥ造粒粉末が脆く、流動性が損なわれる傾向にある。 The stirring speed is preferably 0.5 to 100 m / sec, more preferably 1 to 50 m / sec, and most preferably 2 to 50 m / sec as the peripheral speed of the stirring blade. When the peripheral speed of the stirring blade is high, the PTFE powder tends to strongly agglomerate, so that the resulting PTFE granulated powder tends to harden the inside and increase the bulk density. When the peripheral speed of the stirring blade is low, the PTFE powder tends to be insufficiently aggregated, so that the obtained PTFE granulated powder tends to be brittle and fluidity tends to be impaired.
また、造粒後のＰＴＦＥ造粒物を媒体から分別し易くするため、減圧下でＰＴＦＥ粉末、水、ＨＦＥの混合物を攪拌しても良い。減圧下で攪拌することにより、系内からＨＦＥの蒸気を多量に含むガスが吸引され、混合物から連続的に速やかにＨＦＥを蒸発させることができる。また、吸引ガスからＨＦＥを回収して再利用する上でも有利となる。 Further, in order to facilitate separation of the PTFE granulated product after granulation from the medium, a mixture of PTFE powder, water and HFE may be stirred under reduced pressure. By stirring under reduced pressure, a gas containing a large amount of HFE vapor is sucked from the system, and HFE can be continuously and rapidly evaporated from the mixture. It is also advantageous in recovering HFE from the suction gas and reusing it.
ＰＴＦＥ粉末、水、ＨＦＥの他に、更に、ガラス繊維、カーボン繊維、ブロンズ、グラファイト等の粉末状のフィラー、溶融成形可能な他のフッ素樹脂や耐熱性樹脂等のＰＴＦＥ以外の粉末材料を配合して造粒を行うと、ＰＴＦＥ以外の粉末材料を含有するＰＴＦＥ造粒粉末が得られる。ＰＴＦＥ以外の粉末材料を配合する場合、ＰＴＦＥ粉末と他の粉末材料とを予め乾式で均一に混合して混合粉末を得て、この混合粉末を水とＨＦＥとの２相液体媒質中で、攪拌して造粒することが好ましい。 In addition to PTFE powder, water, and HFE, powdery fillers such as glass fiber, carbon fiber, bronze, and graphite, and powder materials other than PTFE such as other fluororesins and heat-resistant resins that can be melt-molded are blended. When granulation is performed, PTFE granulated powder containing a powder material other than PTFE is obtained. When blending powder materials other than PTFE, PTFE powder and other powder materials are mixed in advance in a dry manner to obtain a mixed powder, and this mixed powder is stirred in a two-phase liquid medium of water and HFE. And granulating.
また、フィラーを配合する場合、造粒時に平均粒径０．１〜０．５μｍのＰＴＦＥコロイド状分散液を更に配合することが好ましい。該ＰＴＦＥコロイド状分散液を配合するとＰＴＦＥ粉末とフィラーの分離が防止できる。ＰＴＦＥコロイド状分散液の配合は、フィラーの配合割合が多い場合により有用である。ＰＴＦＥコロイド状分散液の使用量は、ＰＴＦＥ粉末に対し１〜５質量％が好ましい。 Moreover, when mix | blending a filler, it is preferable to mix | blend PTFE colloidal dispersion liquid with an average particle diameter of 0.1-0.5 micrometer at the time of granulation. When the PTFE colloidal dispersion is blended, separation of the PTFE powder and the filler can be prevented. The blending of the PTFE colloidal dispersion is more useful when the blending ratio of the filler is large. The amount of the PTFE colloidal dispersion used is preferably 1 to 5% by mass with respect to the PTFE powder.
造粒後、ＰＴＦＥ造粒物を媒体から分別し、得られたＰＴＦＥ造粒物を乾燥することによってＰＴＦＥ造粒粉末が得られる。 After granulation, the PTFE granulated product is separated from the medium, and the obtained PTFE granulated product is dried to obtain a PTFE granulated powder.
分別は、メッシュフィルター、フルイ等を用いて行うことができる。また、ＰＴＦＥ造粒物の乾燥は、５０〜３２０℃で３０分〜２４時間行うことが好ましい。これにより、ＰＴＦＥ造粒物から、含有される水やＨＦＥをほぼ完全に除去できる。 Separation can be performed using a mesh filter, a sieve or the like. The PTFE granulated product is preferably dried at 50 to 320 ° C. for 30 minutes to 24 hours. Thereby, the contained water and HFE can be almost completely removed from the PTFE granulated product.
本発明の製造方法によって得られるＰＴＦＥ造粒粉末の平均粒径は、原料であるＰＴＦＥ粉末の平均粒径の好ましくは５倍以上であって、１５０〜１０００μｍが好ましい。より好ましくは２００〜８００μｍである。本明細書において、ＰＴＦＥ造粒粉末の平均粒径は、実施例に記載の方法で、メッシュのフルイを重ねて、ＰＴＦＥ造粒粉末をフルイ分けし、その質量が積算で５０％となる値である。 The average particle size of the PTFE granulated powder obtained by the production method of the present invention is preferably 5 times or more the average particle size of the PTFE powder as a raw material, and is preferably 150 to 1000 μm. More preferably, it is 200-800 micrometers. In this specification, the average particle diameter of the PTFE granulated powder is a value at which the mass of the PTFE granulated powder is 50% in an integrated manner by overlapping the mesh sieve and dividing the PTFE granulated powder by the method described in the examples. is there.
ＰＴＦＥ造粒粉末のかさ密度は０．５０〜１．２０が好ましく、０．６０〜１．００がより好ましい。この範囲にあると、圧縮成形時の圧力伝達性が良好で、引張強さや伸びに優れた成形品を与えることができる。 The bulk density of the PTFE granulated powder is preferably 0.50 to 1.20, more preferably 0.60 to 1.00. Within this range, a pressure-transmitting property at the time of compression molding is good, and a molded product having excellent tensile strength and elongation can be provided.
次に、実施例及び比較例により本発明をより詳細に説明するが、本発明はこれらに限定されない。 EXAMPLES Next, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to these.
［測定方法］
ＰＴＦＥ造粒粉末のかさ密度：ＪＩＳ−Ｋ ６８９１に準じて、１００ｍｌ容量のＰＴＦＥ造粒粉末の質量を測定し、求めた。
ＰＴＦＥ造粒粉末の平均粒径：上から順に１６、２０、２４、２８、３５、６０および１５０メッシュのフルイを重ね、１６メッシュのフルイに１００ｇのＰＴＦＥ造粒粉末をのせてふるい、各フルイ上に残る粉末の質量を求め、積算で５０％となる粒径（Ｄ＝５０）を平均粒径とした。
引張強度及び伸び：ＰＴＦＥ造粒粉末を、３１．４ＭＰａの圧力で予備成形を行い、３８０℃で４時間焼成したのち、室温まで冷却して得られたブロックを厚さ０．５ｍｍにかつら剥きしたシートを、ＪＩＳ−Ｋ ６８９１に規定された３号ダンベルで打ち抜いた試料を用い、ＪＩＳ−Ｋ ６８９１の条件で測定した。
[Measuring method]
Bulk density of PTFE granulated powder: According to JIS-K 6891, the mass of a 100 ml PTFE granulated powder was measured and determined.
Average particle size of the PTFE granulated powder: 16, 20, 24, 28, 35, 60 and 150 mesh sieves are stacked in order from the top, and 100 g of PTFE granulated powder is placed on the 16 mesh sieve and sieved. The particle size (D = 50) of 50% in total was determined as the average particle size.
Tensile strength and elongation: PTFE granulated powder was preformed at a pressure of 31.4 MPa, fired at 380 ° C. for 4 hours, and then cooled to room temperature, and the resulting block was peeled off to a thickness of 0.5 mm. The sheet was measured under the conditions of JIS-K 6891 using a sample punched with a No. 3 dumbbell specified in JIS-K 6891.
［例１（実施例）］
容量１３５リットルで、中央に平ブレード６枚羽根を上下２段に配した攪拌機を有する邪魔板４枚付きのステンレス製円筒形の造粒槽に、水の７９ｋｇと、有機媒体としてＣＦ３ＣＨ２ＯＣＦ２ＣＨＦ２（沸点は５６℃）の１１．２ｋｇと、平均粒径３６μｍのグラニュラータイプのＰＴＦＥ粉末の１６．２ｋｇとを加えた。槽内温度を２８℃に調整し、回転数６００ｒｐｍで４５分間攪拌を続けた。次いで、回転数を３４０ｒｐｍとし、槽内温度を有機媒体の沸点まで上昇させながら３６分間攪拌を行った。そして、回転数を３４０ｒｐｍとし、槽内温度を有機媒体の沸点に維持し、蒸気を１０分間かけて回収した。その後、回転数を１３０ｒｐｍとし、槽内温度を有機媒体の沸点に維持した状態で１０分かけて槽内圧力を０．０２３ＭＰａ（絶対圧）に減圧し、有機媒体を蒸発回収してＰＴＦＥ粉末が凝集した造粒物を得た。槽内温度を室温まで冷却し、水中に分散した造粒物をひらき目２００μｍのメッシュフィルターで分別し、３００℃で９時間乾燥してＰＴＦＥ造粒粉末を得た。得られたＰＴＦＥ造粒粉末のかさ密度は、０．８０ｇ／ｍｌで、平均粒径は４４０μｍであった。また、このＰＴＦＥ造粒粉末を用いて得た成形品の引張強度は４０．４ＭＰａで、伸びは３４９％であった。
[Example 1 (Example)]
A stainless steel granulation tank with four baffle plates with a stirrer with a capacity of 135 liters and six flat blades arranged in the upper and lower stages in the center, 79 kg of water and CF 3 CH 2 as the organic medium. 11.2 kg of OCF 2 CHF 2 (boiling point is 56 ° C.) and 16.2 kg of granular type PTFE powder having an average particle size of 36 μm were added. The temperature in the tank was adjusted to 28 ° C., and stirring was continued for 45 minutes at a rotation speed of 600 rpm. Subsequently, stirring was performed for 36 minutes while setting the rotation speed to 340 rpm and increasing the temperature in the tank to the boiling point of the organic medium. And rotation speed was set to 340 rpm, the temperature in a tank was maintained at the boiling point of the organic medium, and vapor | steam was collect | recovered over 10 minutes. Thereafter, the rotational speed was set to 130 rpm, the pressure in the tank was reduced to 0.023 MPa (absolute pressure) over 10 minutes with the temperature in the tank maintained at the boiling point of the organic medium, the organic medium was evaporated and recovered, and the PTFE powder was recovered. Agglomerated granules were obtained. The temperature in the tank was cooled to room temperature, and the granulated product dispersed in water was fractionated with a mesh filter having a opening of 200 μm and dried at 300 ° C. for 9 hours to obtain PTFE granulated powder. The bulk density of the obtained PTFE granulated powder was 0.80 g / ml, and the average particle size was 440 μm. Moreover, the tensile strength of the molded article obtained using this PTFE granulated powder was 40.4 MPa, and the elongation was 349%.
［例２（比較例）］
実施例１において、有機媒体として、ＣＦ３ＣＨ２ＯＣＦ２ＣＨＦ２のかわりに、ＣＦ３ＣＦ２ＣＦ２ＣＦ２ＯＣＨ３（沸点は６１℃）を用いた以外は例１と同等の操作を行い、ＰＴＦＥ造粒粉末を製造した。得られたＰＴＦＥ造粒粉末のかさ密度は、０．８２ｇ／ｍｌで、平均粒径は４６０μｍであった。また、このＰＴＦＥ造粒粉末を用いて得た成形品の引張強度は３４．９ＭＰａで、伸びは３１９％であった。
[Example 2 (comparative example)]
In Example 1, the same operation as in Example 1 was performed except that CF 3 CF 2 CF 2 CF 2 OCH 3 (boiling point was 61 ° C.) was used as the organic medium instead of CF 3 CH 2 OCF 2 CHF 2. PTFE granulated powder was produced. The bulk density of the obtained PTFE granulated powder was 0.82 g / ml, and the average particle size was 460 μm. Moreover, the tensile strength of the molded product obtained using this PTFE granulated powder was 34.9 MPa, and elongation was 319%.
［例３（比較例）］
実施例１において、有機媒体として、ＣＦ３ＣＨ２ＯＣＦ２ＣＨＦ２のかわりに、ＣＦ３ＣＦ２ＣＦ２ＣＦ２ＯＣＨ２ＣＨ３（沸点は７６℃）を用い、有機媒体を蒸発回収時に槽内温度を有機媒体の沸点に維持した状態で１０分かけて槽内圧力を０．０４０ＭＰａ（絶対圧）に減圧した以外は例１と同等の操作を行い、ＰＴＦＥ造粒粉末を製造した。得られたＰＴＦＥ造粒粉末のかさ密度は、０．８４ｇ／ｍｌで、平均粒径は４７０μｍであった。また、このＰＴＦＥ造粒粉末を用いて得た成形品の引張強度は３４．７ＭＰａで、伸びは３２９％であった。
[Example 3 (comparative example)]
In Example 1, CF 3 CF 2 CF 2 CF 2 OCH 2 CH 3 (boiling point is 76 ° C.) is used as the organic medium instead of CF 3 CH 2 OCF 2 CHF 2 , and the organic medium is stored in the tank at the time of evaporative recovery. A PTFE granulated powder was produced in the same manner as in Example 1 except that the pressure in the tank was reduced to 0.040 MPa (absolute pressure) over 10 minutes while maintaining the temperature at the boiling point of the organic medium. The bulk density of the obtained PTFE granulated powder was 0.84 g / ml, and the average particle size was 470 μm. Moreover, the tensile strength of the molded product obtained using this PTFE granulated powder was 34.7 MPa, and elongation was 329%.
上記結果を表１にまとめて記す。 The results are summarized in Table 1.
Claims (5)
Ｒ１−Ｏ−Ｒ２ ・・・（１）
（式（１）中、Ｒ１及びＲ２はポリフルオロアルキル基であり、Ｒ１及びＲ２の少なくとも一方は水素原子を有し、Ｒ１とＲ２の合計の炭素原子数は３〜８である。） The average particle diameter 200μm or less polytetrafluoroethylene powder, to the polytetrafluoroethylene powder 1 part by weight, of water 2 to 30 parts by mass, hydro fluoroalkyl ether 0.2 represented by the following formula (1) Production of polytetrafluoroethylene granulated powder , characterized in that it is granulated by stirring in a two-phase liquid medium containing 2 parts by mass to obtain a polytetrafluoroethylene granulated powder having an average particle size of 200 to 800 μm Method.
R 1 —O—R 2 (1)
(In the formula (1), R 1 and R 2 are polyfluoroalkyl group, at least one of R 1 and R 2 are a hydrogen atom, R 1 and the total number of carbon atoms in R 2 is 3-8 .)
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