Пересылка - Новая Почта. Возможно Мистом/Укрпочтой, ими реже.
состав PTFE (тефлон) / PFPE (перфторполиэфиры)
Идеальна для смазки вентиляторов. Можно также смазывать клавиатурные свичи (убедитесь что вязкость соответствует рекомендациям для ваших свичей), пластиковые детали в принтерах например и вообще что угодно в пределах температурных допусков.
Производство Solvay Solexis, сделано в Италии.
Цена за 1 грамм - 200 грн
Расфасовка от 0,5г, это 100 грн. Упаковка обычно инсулиновые шприцы, входит до 1,5г в шприц. Взвешиваю на весах 0,01г. На вид - белая мазь. В шприце могут быть пузырьки воздуха, вес при этом не меняется.
Расход на типичный вентилятор практически отсутствует, порядка 0,05г плюс минус. Поршень почти не сдвигается. Из-за того, что смазка не вырабатывается/высыхает/вытекает, закладывать ее нужно в несколько раз меньше, чем обычные смазки. В идеале промыть растворителем, на практике работает и так, по старой смазке.
Без добавок, без силиконов. Чистый мелкодисперсный (или нано, в даташите размер частиц не указан, но это микроны или доли микронов, см. патенты) тефлон PTFE во перфторполиэфирной жидкости (растворителе) PFPE. Не смывается ничем кроме фтористых жидкостей, не вырабатывается, не портится, не загустевает, не окисляется, не меняет вязкость в широком температурном диапазоне, не токсичная, ни с чем не взаимодействует, химически инертная, не проводит электрический ток, стойкая к радиации, не растворяется даже в кипящей азотной кислоте и щелочах... вечная смазка. Допуск NASA есть, можно смазать свое кислородное оборудование и стартовать.
Относится к уникальному по своим свойствам классу PFPE (ПФПЕ или перфторполиэфиры) — это семейство смазочных материалов, основанных на синтетических фторированных жидкостях. Перевод - фтористая жижа и мельчайшие частицы тефлона (фторопласта) в качестве загустителя.
Используется для смазки различного дорогостоящего оборудования - микромеханического и оптического оборудования, уплотнителей, подшипников, пластиковых деталей, оборудования в среде кислорода и высоких температур до 200-300 градусов, оборудования в условиях вакуума. Например, фирменная смазка часов Rolex для уплотнителя крышки - это именно UT-18.
Универсальная смазка. Можно смазывать что угодно, получая при этом недостижимый для традиционных смазок результат. Исключение - температуры выше 200-300 градусов и сверхвысокие нагрузки.
Обращаю внимание - это не "сухая смазка"/порошок фторопласта (тефлона) непонятного помола и это не смесь силикона/литола/чегоугодно с порошком тефлона. Это совсем другое.
Личный опыт.
- спойлер
- 1) 14см втулочный Yate Loon из брендового блока питания, стоял 3 года горизонтально в бп, потом год вертикально на корзине с hdd. В полной тишине начал каждые несколько секунд постукивать, еле слышно. Смазал, сначала без изменений, но через месяц стуков уже не было, так и работает. Это лет 5 назад.
2) 6см дешевый втулочный из 12в зарядки для свинцовых аккумуляторов (зус, зарядное устройство им. Сороки, широко известного в узких кругах новатора, полторы сотни денег отдал в 2012). Уже через месяц начал сурово гудеть, через год клинить. Смазал, гула стало гораздо меньше, клины прекратились. Через несколько лет такой работы большую часть времени крутится бесшумно, иногда немного гудит, потом перестает. так работает с 2013, практически постоянно.
2) клиника. Два 9см брендовых sunon, с двумя шариковыми подшипниками, из powerware 9120 2000va. Купил ибп в 2012 б/у, вентиляторы сурово гудели, один постоянно клинил. Ибп из холодной серверной с пробегом 5 лет, почему так. Разобрал, у одного развалился подшипник на куски. У второго подшипники вытащил, благо все разборное, промыл бензином, там все сухое и с явными признаками износа. смазал. Результат - воскрешение, как новый. Буквально - после этого нашел несколько таких же точно sunon выпуска конца 90х, новых, поставил в ибп. Один новый, второй восстановленый. Разницы нет. ибп работает на систему отопления по 4-5 месяца в году с этими вентиляторами.
С одной стороны, поздно пить Боржоми, если почки отвалились. Физическую выработку никакой смазкой не исправить, за "ревитализацией" в хадо нужно обращаться. С другой стороны, эффект более чем заметный. Чем более уставший вентилятор, тем больше заметный. Создалось впечатление, что смазка кулеров сновья или пока они не начали шуметь - увеличивает их срок жизни примерно на порядок. Очевидно, использование таких смазок не выгодно самим производителям вентиляторов. Не могу гарантировать чудес, но эта смазка походу из ряда лучших существущих. На острии прогресса так сказать.
Далее технические подробности.
PFPE - перфторполиэфирная жидкость, базовое масло (https://www.solvay.com/en/brands/fombli ... lubricants). они разные бывают. из любых подшипников сразу вымоется, т.к. жидкая так или иначе.
Fomblin® PFPE are fluorinated lubricants representing the best choice when aggressive chemical environments, high temperatures or wide working-temperature ranges are involved.
Fomblin® PFPE lubricants are engineered for those applications where heat, chemicals, solvents, corrosion, toxicity, flammability, and service life present lubrication problems. While Fomblin® PFPE lubricants can be used in their original form, they are often formulated into greases for specific applications in the chemical, electronic, military, nuclear, data processing, and other industries in need of high performance lubrication.
Поэтому для получения консистентных смазок (более густых) их смешивают с загустителем.
Сам тефлон в виде порошка продается и стоит недорого, называется часто "сухой смазкой". Это шляпа для замков и велосипедов, так как порошок сыпучий, на поверхностях не держится, ну и степень помола там соответствует цене. Часто его добавляют несколько % в любые обычные смазки и лепят буквы "PTFE - с тефлоном!", потому что тефлон это модно. Иногда как базовое масло используют силиконовую жидкость типа ПМС, она стоит копейки. Получается антикризисная тефлоновая смазка на базе силиконов, ссылки тут давали в теме. Перфторполиэфиры PFPE используют крайне редко, потому что они дорогие.
смысл предлагаемой в теме смазки в том, что она сделана из чистой перфторполиэфирной жидкости (PFPE) и чистого тефлона, размолотого до частиц округленной формы размером чуть ли не до единиц микрон. Процесс производства и равномерного перемешивания защищен патентами, потому что настолько мелко перемолотые частицы очень не любят разделяться и равномерно их перемешать - серьезная производственная задача. Там все довольно подробно описано, какие мешалки, сколько часов это все длится, какие этапы, какие реагенты. Поэтому продукт на выходе обладает выдающимися характеристиками и стоит ... дорого.
Ссылки на общую инфу по PTFE смазкам:
раз
два
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Характеристики
- спойлер
- Вязкость при 20 С, cSt: 500 единиц
Загуститель: PTFE
Класс по NLGI: 2
Антикорр.добавки: без добавок
Диапазон рабочих температур:-30/+250
Совместимость с растворителями: растворяется только в перфтороктане, Dilifren LS, Galden SV и другими. В воде, бензине и др. веществах не растворяется.
Информация производителя
- спойлер
- Общие Свойства
Смазки Fomblin - гомогенные, белые, густые вещества особенно стойкие к окислению и химикатам. Они совместимы со всеми типами материалов (стекло, металлы, эластомеры, пластмассы, керамика) и их свойства остаются неизменными в широком температурном диапазоне. Смазки Fomblin могут использоваться в присутствие воды, нефти, пара и, вообще со всеми не высокофторированными органическими веществами и растворителями без малейшего ухудшения своих свойств.
UT 18: UT 18 - гомогенная белая смазка для смазки механических частей, используемых в широком
температурные интервале (от-30 to 150 C, с временным пиком до 200 C). UT18 является особенно подходящим для смазки трущихся механических частей, подвергнутых средней нагрузке, где стандартные минеральные и синтетические смазки нестойки к температуре и воздуху. UT 18 также используется в специальном оптическом и микромеханическом оборудовании.
Стандартные Свойства Смазок Fomblin.
Тепловая стабильность: смазки Fomblin работоспособны до 300 C и могут использоваться при высокой температуре в окисляющей среде.
Химическое сопротивление: смазки Fomblin инертны и не реагируют даже при высокой температуре с топливом, кислотами, щелочами, галогенами, кипящей азотной кислотой и окислителями.
Растворимость: смазки Fomblin устойчивы, не превращаются в эмульсию с водой и стойкие ко всем растворителям кроме высокофторированных . Поэтому такие растворители как Delifrene LS (1, 1, 3 Trichlorotrifluoroethane) и Galden SV, могут использоваться для очистки поверхности контактирующие с
смазками Fomblin.
Совместимость с кислородом: Bundesanstaltfur Materialprufung, Берлин (BAM), Национальное Агентство Космической Аэронавтики (НАСА) и Инженерный Центр ВМС США одобрили использование жидкостей Fomblin и смазок в среде жидкого кислорода.
Совместимость с металлами и структурными материалами: смазки Fomblin совместимы со всеми типами полимеров, пластомеров и эластомеров. В течение теста длившегося более чем один месяц при 20 C ни один из этих материалов (нитрил, бутил, полифторсилоксан, каучук EPDM) не претерпел химических или физических изменений.
- спойлер
- https://www.idealvac.com/PERFLUOROSOLV- ... pp/P102609
The application of PFS-2 for the removal of a PFPE grease, such as Fomblin Y-VAC 3, is a bit more complicated. These greases as mixtures of a finely ground PTFE(polytetrafluoroethylene) powder with a Fomblin PFPE liquid, generally one that is used or could be used as a diffusion pump fluid in a high vacuum system. PFS-2 is able to solve only the liquid component of the grease. This means that for the composite structure, the PFS-2 removes the liquid phase but not the solid particulate phase, and it should be pointed out that there is no known solvent for the PTFE particles. Hence, the application of PFS-2 in a grease removal situation, will do some good for sure, however some kind of mechanical actions will be required for the removal of the solid particulates.
Перевод - фтористую жижу можно растворить и удалить специальными растворителями, для удаления оставшихся частиц тефлона придется поработать с тряпочкой, иного пути нет.
- спойлер
- гуглим по "fomblin ptfe greases patent", видим патенты итальянцев из Solvay Solexis на разные темы. оказывается там да, НАНОчастицы тефлона, в разных патентах от 5 до 300нм. я не знаю технологию производства именно ut-18, но принцип такой же.
например, как доработать изначальные технологии 60х:
Abstract
Fluorinated greases comprising (by weight):
15%-50%
polytetrafluoroethylene or tetrafluoroethylene copolymers with other ethylenically unsaturated monomers;
30%-84.5%
perfluoropolyether oil having a viscosity comprised between 20 and 4000 mm 5-1 (cSt) at 20 °C;
0.5%-10%
surfactant or dispersant having perfluoropolyether or perfluoroalkyl chain;
0%-10%
of an anticorrosion and/or antiwear additive,
such that the (per)fluoropolymer particles based on TFE or their aggregates have average sizes lower than one micrometer and show WEAR diameter values, lower that at least 25% with respect to those of the corresponding fluorinated grease of the prior art, the components of the formulation being equal.
...The processes for preparing greases are at present based on the dispersion in the lubricating oil PFPE of dry powder of the fluorinated polymer.
The drawbacks of such techniques reside in the fact that the dry powder is formed by coagula and therefore it is necessary a finishing treatment to reduce the coagula size and to homogenize the system in order to obtain the desired lubricating properties.
...
The utilized latex contained a terpolymer formed by TFE-FMVE-FPVE in molar ratio 96.15:3.5:0.35 and prepared according to the process described in Example 1 of EP 633,274. The polymer particles sizes were 75 nm of average diameter. The obtained latex had a concentration of 30.8% by weight of polymer...
...The polymer content in the latex was of 14.4% by weight and the particles had an average diameter of 70 nm...so as to obtain a dispersion of aggregates of polymer particles in aqueous phase with average diameter lower than 400 nm, with wide dimensional distribution which comprises also the polymer primary particles of 75 nm.
далее практически мануал по производству от 1982 года (Solvay Specialty Polymers Italy SpA) просто песня на тему "как нам все это размешать равномерно" https://patents.google.com/patent/EP0605403A2
в результате The diameters of the particles varied from 0.13 microns (2% fraction) to 0.35 microns (0.5% fraction), the average diameter value being 0.19 microns. средний размер частиц 190 нанометров. болдом выделил перемешивание.
то, что продают в баночках "силиконово-тефлоновая смазка", "тефлон", "суперсмазка" во всяких непонятных местах и индустриальные смазки (которые вы еще попробуйте купить) - это разные миры.
Abstract
The invention provides the use of a compound selected from:...as anti-wear additives for a lubricating grease based on polytetrafluoroethylene (PTFE) in the form of fine particles and on a liquid dispersant selected from an oligomer of trifluoro-chloroethylene or from a perfluoropolyether.Description
This invention relates to a process for preparing lubricating greases, particularly lubricating greases based on polytetrafluoroethylene and perfluoropolyethers.
As is known, the most common and general method of preparing greases consists in suspending a thickening filler in a liquid or waxy dispersing medium.
In particular, when the thickening filler does not consist of a soap (such as for example the derivatives of lithium, sodium, or calcium of fatty acids), or at any rate of a compound capable of forming a colloidal solution or a suspension stable in the dispersing liquid, the grease tends to show a lack of stability with the passing of time and to lose its original lubricating properties as well as, at worst, to suffer a separation of the oil during ageing (separation of oil as defined by the IP 121/75 and FTMS 791-321 standards), with the ensuing deterioration of the rheological and tribological properties.
It is known that a fluorinated grease may be formulated (see for example J. Messina, J. Am. Soc. of Lubr. Eng.(Dec.1969) 475-481, and Italian Patent No. 963 579) by suspending a polytetrafluoroethylene telomer having an average molecular weight of 20,000 - 30,000 and partially chlorinated chain terminals (as a result of the radical polymerization method in suspension of 1,1,2-trichlorotrifluoroethane) in a perfluorinated liquid, such as for example the perfluoropolyethers described in Italian Patent Nos. 792 673 and 790 651.
The above perfluoropolyethers have the commercial name Fomblin Y and the general formula
Figure imgb0001
and respectively Fomblin Z having the general formula
Figure imgb0002
in which the oxyperfluoroalkylene units are statistically distributed along the chain, wherein in formula (I) X and Y are a terminal -CF3 or -C2F5 group, and m and n are integers the sum of which ranges from 10 to 100 and the m/n ratio ranges from 10 to 50; and in formula (II) A and B are terminal -CF3, -C2Fs, -CF2CI, or -CF2CF2CI groups, and p and q are integers the sum of which ranges from 10 to 200 and the p/q ratio ranges from 0.1 to 10.
ratio has a value ranging from 0.01 to 0.3 and the r/s ratio has a value ranging from 0.1 to 10.
The products of formula (III) may be obtained by reacting a perfluorinated olefin on a perfluoropolyether containing peroxide groups, in the presence of U.V. radiation.
These products and the preparation thereof are described in Italian Patent Application No. 20270 A/82 filed by the present Applicants.
The polytetrafluoroethylene telomer defined hereinbefore is usually obtained as a 7% suspension in 1,1,2-trichlorotrifluoroethane in which the average diameter of the particles of the telomer is less than 30 microns.
The known formulation method consisted in gradually adding the perfluoropolyether to the 7% polytetrafluoroethylene suspension, or to a partially concentrated suspension at 50-60%, by simultaneously evaporating the solvent under vacuum.
The resulting grease exhibits good lubricating properties; however, the process is very long and complex. In particular, the preparation of an amount of about 30 kg of grease involves the mixing of a volume up to about 50 liters of telomer suspension with the dispersing liquid; it is therefore necessary to evaporate from the mixture up to about 45 liters of solvent, which, since it is miscible in perfluoropolyether, tends to leave in the final grease a small amount of non-evaporable residue which is harmful as regards both the stability of the grease and the evaporation at high temperature or under vacuum. Usually, the solvent evaporation step takes from 20 to 45 hours.
Furthermore it is not possible to readily increase the scale of each preparation owing to the difficulty due to the heat and mass exchange in too great volumes. Moreover, both the high-temperature evaporating properties and the heat stability properties of the grease are adversely affected by the relatively low thermal stability of the telomer, owing to the presence of chlorinated chain terminal groups. It is known in fact that the C-Cl bond is less stable than the C-F bond.
The thermal stability of the telomer is lower than that of the Fomblin liquid; as a consequence the improved thermal resistance properties obtained by employing Fomblin instead of other suspending fluids are partially lost.
It was previously known that the best performances of a polytetrafluoroethylene as a thickening agent for a liquid in order to provide a grease corresponded to the described telomer (Journal ASLE 1969, 12, page 475, J. Messina).
The present invention relates to a new process for preparing lubricating greases in which, as an essential ingredient, polytetrafluoroethylene having a molecular weight not below 50,000 and a high thermal stability is employed in the form of particles in suspension in a perfluorinated liquid of the type of perfluoropolyethers described hereinbefore or of the type of oligomers of trifluorochloroethylene having a viscosity ranging from 100 to 1,000 cst at 20 °C.
It is known to obtain, by polymerization of tetrafluoroethylene in an aqueous dispersion with the use of ammonium persulphate and a Mohr salt, a polymer having a molecular weight ranging from 500,000 to 1,000,000. The particles of such a polymer, after separation from the dispersing medium, are found to consist of aggregates with sizes ranging from 1 to 200 microns, such aggregates consisting of primary particles with sizes ranging from 0.05 to 0.5 microns, which have either a spherical shape or the shape of a rounded rod with the major axis below 0.5 microns. The particles have a surface area of from 5 to 15 m2/g.
The present invention provides a process for preparing a lubricating grease based on polytetrafluoroethylene and on a liquid dispersant selected from oligomers of trifluorochloroethylene or from perfluoropolyethers of the classes of general formula characterized in that polytetrafluoroethylene having a molecular weight in the range of from 500,000 to 1,000,000, comprising particles of the aggregated type, previously heated under vacuum to remove volatile products which may be contained therein, is mixed, under reduced pressure and at a temperature higher than room temperature, with an oligomer of CF2 CFCI having a viscosity, at 20 °C, from 100 to 1000 cst, or with a perfluoropolyether selected from the classes (I), (II) or (III) and having a viscosity, at 20 °C, from 20 to 4000 cs if belonging to class (I), from 40 to 6000 cs if belonging to class (II), and from 40 to 30,000 cs if belonging to class (III), and also with a perfluorinated surfactant of the anionic type, characterized by a perfluoroalkylene chain or by a perfluorooxyalkylene chain, the amount of polytetrafluoroethylene being from 15% to 40% by weight of the total mix, the amount of perfluoropolyether or of oligomer of CF2CFCI being from 60% to 85% by weight of the total mix, and the amount of surfactant being from 0.1% to 0.4% by weight of the polytetrafluoroethylene.
It has now been found that it is possible to attain the disaggregation of the aggregated particles of polytetrafluoroethylene into primary particles having sizes ranging from 0.05 to 0.5 microns of rounded or spherical shape, when the aggregated particles are soaked or suspended in a perfluorinated liquid selected from: perfluoropolyether of the Fomblin Y type of formula (I) having a kinematic viscosity of from 20 to 4000 cst at 20 °C, preferably from 40 to 1600 cst at 20 °C, or of the Fomblin Z type of formula (II) having a viscosity of from 40 to 6000 cst at 20 °C, preferably from 50 to 6000 cst at 20 °C, more preferably from 60 to 6000 cst at 20 °C, or a perfluoropolyether of formula (III) having a kinematic viscosity of from 40 to 30,000 cst at 20 °C, preferably from 60 to 28,000 cst, or an oligomer of trifluorochloroethylene having a kinematic viscosity of from 100 to 1000 cst, and then the aggregated particles of polytetrafluoroethylene suspended in the Fomblin liquid are subjected to a grinding or disaggregating process in a refiner, thus directly obtaining the grease having the final rheological and mechanical properties as desired.
In particular, the soaking and suspending process of the polytetrafluoroethylene particles of the aggregated type having sizes from 1 micron up to 200 microns, and consisting of aggregations of spherical or rounded rod-like particles of submicronic sizes, may be accomplished as follows :
(1) The inner voids of the polytetrafluoroethylene particles are evacuated from air and condensed vapours (e.g. water vapours) by means of heating for about 2 hours at 50 °C under a vacuum of the order of 10-1-10-3 torr.
(2) The particles so treated are subjected to a soaking and suspending treatment, at a temperature higher than the room temperature and under reduced pressure, with a perfluoropolyether liquid such as Fomblin Y or Z or of formula (III), or with a CF2CFCI oligomer as defined hereinbefore, which has previously been deaerated. The perfluoropolyethereal liquid possesses a high air-solubilizing power, up to 20% by volume at 20°C and at atmospheric pressure. Polytetrafluoroethylene is employed in amounts of from 15 to 40% by weight, preferably from 18 to 35% by weight, calculated on the basis of the total mix.
(3) The perfluoropolyether or the CF2CFCI oligomer, used in an amount of from 60 to 85% by weight, preferably from 65 to 82% by weight, referred to the total mix, is additioned with a perfluorinatedsurface- active agent of the anionic type having a perfluoroalkylene chain, of general formula
Figure imgb0009
wherein n is an integer from 2 to 12, preferably from 3 to 8, more preferably from 3 to 7, and D is selected from the groups -COOM, -S03M and -OC2F4SO3M where M is a cation selected from Na, K, 1/2Ba and 1/2Ca, or with a surface-active agent of the polyoxyperfluorinated anionic type of general formula
Figure imgb0010
wherein R is either like or unlike Q and is selected from CF3- and MOCOCF2- in which M is a cation as defined hereinabove, and Q is a -CF2COOM group where M is a cation as defined hereinabove, provided that when R is the same as Q, i is equal to zero; oxyperfluoroalkylene units C2F4O, C3F6O and CF20 are statistically distributed along the chain, provided that the C3F6O and C2F4O units are not present contemporaneously; i and k are equal to zero or are integers from 1 to 7, preferably from 1 to 4, h is an integer from 1 to 7, and the sum of i, k and is an integer from 2 to 10, preferably from 2 to 6.
The surface-active agent is employed in amounts of from 0.1% to 0.4%, preferably from 0.2 to 0.3%, by weight, in respect of the polytetrafluoroethylene powder.
Some examples of surface-active agents which have provided excellent results are the following :
CF3 - (CF2)6-COONa
CF3 - (CF2)6-COOK
(CF3 -(CF2)5COO)2Ca
(CF3 -(CF2)7COO)2Ba
CF3 - (CF2)6-SO3K
CF3 - (CF2)5SO3Na
CF3 - (CF2)7S03K
CF3 - (CF2)3- O - CF2 - CF2 - S03K
CF3- (CF2)5 - O - CF2 - CF2 - SO3K
Figure imgb0011
Figure imgb0012
Na00C-CF20-(C2F40)2-(CF20)2 - CF2COONa .
The soaking of polytetrafluoroethylene of the described type with perfluoropolyether liquid leads to a very viscous pasty suspension. Such suspension is subjected to disaggregation or grinding of the aggregated particles into primary particles by treatment in a refiner such as a triple roll mill, for example of the type manufactured by Officine Meccaniche Molteni, Italy.
Such a machine consists of three parallel rolls cooled by inside circulation of water and adjustable as to revolving speed and gap between the rolls; the adjacent rolls revolve in opposite directions to each other and at different speeds; furthermore they may be put into contact with each other so as to exert a pressure, while the pressure exerted on the suspension of polytetrafluoroethylene in perfluoropolyether may be hydraulically regulated at from 1 to 50 atmospheres by a control servofluid.
The suspension is introduced between the first roll revolving at low speed and the second roll which revolves at an intermediate speed, and is then extracted after having passed between the second roll and the third roll, which revolves at a higher speed.
It has been found that under the best operational conditions it is necessary that the hydraulic control pressure of the servofluid be from 10 to 75 atmospheres, preferably from 15 to 65 atmospheres, that the speed of the first roll be from 20 to 50 rpm, the speed of the second roll from 60 to 140 rpm, and the speed of the third roll from 150 to 400 rpm.
In particular, the action of total disaggregation of the particles aggregated to primary particles having a spherical shape or the shape of a rounded rod is obtained when the particles of polytetrafluoroethylene powder are fully degassed and the perfluoropolyether liquid has completely wetted all the voids and the gaps formed among the primary particles in the inside of the aggregated particles.
The action of full wetting and soaking of the polytetrafluoroethylene particles having a surface tension of 19-22 dynes/cm is made possible by the low value (17.5-21 dynes/cm) of the surface tension of the perfluoropolyether.
The pressure between the cylinders is hydraulically transmitted homogeneously through the suspension, without formation of any air bubbles due to coalescence among microbubbles, the forming of which could detach the liquid film adhering to the particles or to the rolls, thereby causing sintering phenomena among the particles with formation of new irregular and fibrous aggregates and breaking phenomena of the primary particles.
The particles disaggregate owing to the friction therebetween and with the perfluoropolyether fluid threads adhering to the walls of the revolving rolls or to the other particles.
In order to obtain a disaggregation of the aggregated particles to primary particles without causing a microrupture of the primary particles or the reaggregation or sintering of the particles into fibrous or irregular aggregates, it is necessary to prevent the unwetted particles from coming directly into contact with one another or with the unwetted rolls.
The duration of the adherence of the liquid film to the particles and to the rolls depends, besides on the absence of gases and vapours in the suspension, on the mechanical resistance characteristics of the fluid film adhering to the particles and to the rolls.
Such stabilities of the grease, namely the adherence duration and the mechanical resistance of the liquid adhering to the particles, is improved by the presence of suitable agents having surface activity which probably act as wetting agents, thus increasing the adhesion of the liquid film to the surface.
Such resistance depends besides on the surface tension also on the molecular weight and by consequence on the viscosity of the fluid and on the chemical structure thereof.
The perfluoropolyether fluids possess a high mechanical resistance, as is proved by measurements with the 4-ball Shell test under EP conditions (test IP 239, where welding load values ranging from 400 to 500 kg, corresponding to values higher than the average values of the other additioned fluids, are measured).
On the other hand it may be ascertained how, by using a fluorinated fluid, characterized by a low surface tension (19 dynes/cm) and by a low molecular weight, such as 1,1,2-trichlorotrifluoroethane, as a suspending liquid for the soaking and the disaggregation of polytetrafluoroethylene, it is impossible to obtain a homogeneous disaggregation of the polytetrafluoroethylene powder into primary particles. In fact such liquid does not possess sufficient viscosity and mechanical resistance properties to bring about the protecting action on the particles and to avoid the aggregation and sintering thereof to fibrous particles.
To obtain the desired protecting action, the perfluoropolyether or the CF2CFCI oligomer must possess a viscosity higher than 10 cs at 20 °C, preferably higher than 30 cs at 20°C, as already mentioned hereinbefore.
Furthermore, the mechanical stability of the grease, its wear resistance also when it operates under great loads, and its capability of imparting corrosion resistance to the materials on which it is applied, may be enhanced by the presence of suitable additives such as fluorinated bis-bensimidazoles having the structure :
Figure imgb0013
wherein R may be F, CF3; p and q are integers, and the sum p+q = 10-100, and the p/q ratio = 0.1-2; or such as
the esters of phosphorous acid
Figure imgb0014
or the phosphines such as
Figure imgb0015
wherein C6 H4 is a disubstituted phenyl residue which is bound to trivalent phosphorus. Also suitable are perfluoropolyethers having, at both ends, aryl-substituted phosphonic groups, or phospho-triazinic groups
Figure imgb0016
where Rf is a perfluoroalkyl radical or a polyoxyperfluoroalkyl radical, and Ar is an aryl radical.
If the fluids are additioned by 0.2-1 % by weight of the wear-resisting and corrosion-resisting additives specified hereinabove, their mechanical resistance is improved to such an extent that the welding load with the 4-ball Shell test rises to values of 600-800 kg; furthermore, the corrosion resistance of the metal lubricated and subjected to oxidizing atmosphere conditions improves also.
The tests which permit the obtainment of a grease having satisfactory physical, mechanical, rheological and wear-resisting properties to be ascertained are :
- examination under an optical microscope to ascertain the disappearance of the aggregates and the absence of fibrous aggregates;
- examination under the electron microscope to determine both the shape and the particle size distribution of the primary particles;
- consistency of the grease determined through penetration measurements according to test ASTM D 1403 on the grease as such, handling after the Roll test (ASTM D 1831, at 100°C);
- per cent separation of oil at 100°C (method FTMS 791-321) or at 40°C under load (method IP 121/75);
- mean diameter of the trace left by the wear and wear load under the 4-ball Shell apparatus (tests ASTM D 2266, IP 239);
- loss of oil under evaporation and vapour tension at different temperatures (Knudsen method).
The applicative importance of the grease is found in the following fields :
- lubrication under high loads and under severe chemical and physical conditions where high mechanical, thermal and chemical resistances are required;
- under vacuum, where a high stability to evaporation, i.e. an extremely low vapour tension and a high lubricating power, are required;
- where a high resistance to electromagnetic radiations ( y, X, ultraviolet and Laser rays) and to accelerated particles (electrons, protons and ions) is required.
Such applications are possible particularly due to the combination of perfluoropolyether and polytetrafluoroethylene, in which the C-Cl and C-H bonds of low stability are either absent or extremely few and the C-O and C-F bonds are predominant.
The invention will be further described with reference to the following illustrative Examples.
EXAMPLE 1
7 kg of crystalline polytetrafluoroethylene having a molecular weight of about 600,000, prepared by polymerization in an aqueous dispersion at 60°C and 20 atm. by means of ammonium persulphate and Mohr salt, consisting of aggregated particles having diameters ranging from 1 to 100 microns as determined under an optical microscope, were introduced into a mechanical mixer equipped with Z-shaped arms, a mechanical seal cover with connections for vacuum and for the introduction of liquids as well as for the under vacuum removal of gases and vapours, and with a thermoregulating jacket.
The jacket was thermoregulated at a temperature of 50 ° C while the vacuum-connection of the mixer was connected with a mechanical vacuum pump, whereupon vacuum was created up to a residual pressure of 5.10-2 torr, and such vacuum was maintained for 3 hours.
Into a cylindrical steel tank having a capacity of 20 I, resistant to vacuum and equipped with connections for vacuum and with a heating jacket, there were introduced 16.4 kg (8.6 I) of perfluoropolyethereal oil Fomblin Y produced by Montedison S.p.A., having a kinematic viscosity of 1500 cs (at 20°C), and additioned with 14 kg of a surfactant having the formula CF3(CF2)6COONa.
The oil was heated to 50 ° C and the tank was connected with the mechanical vacuum pump, thus creating in the tank interior a vacuum corresponding to a final residual pressure of 5.10-2 torr for 3 hours. In this way the polytetrafluoroethylene powder and the Fomblin oil were completely freed from gases and volatile vapours.
Successively the arms of the mixer were rotated and, by gravity, the Fomblin liquid was gradually introduced, over a time-period of 30 minutes, into the mixer. Then, heating of the mixer jacket was stopped while continuing stirring the mass for 3 hours until complete cooling to 20 ° C; at the end a pasty suspension was obtained.
On a suspension sample, on a Brookfield rotary viscosimeter, a viscosity of 185,000 cp at 20°C was determined. The suspension was discharged from the mixer and subjected to thickening in a refiner equipped with three rolls of 180 mm diameter, the roll length being 400 mm, by causing the suspension to pass between the rolls revolving at a speed of 40 rpm and of 70 rpm, and then by collecting it through detachment from the surface of the third roll revolving at 150 rpm. The rolls were kept in contact by means of a pressure of the servofluid of about 60 atm. The 23.4 kg of pasty suspension were made to pass between the three rolls in a time-period of 2 hours.
A film consisting of grease thus formed, which was continuously detached from the third roll by means of a steel scraping blade.
A grease sample was drawn and the consistency thereof was measured by a penetration determination according to the ASTM D 1403 method (half scale) at a temperature of 25 ° C. A value of 245 (mm/10) was found.
The grease was made to pass another four times between the rolls kept at the same speed and at the same distance from one another, thus obtaining, in order, the following penetration values as a consistency measure :
Figure imgb0017
The succession of values shows that on the 4th passage a mechanically stable grease was obtained.
A sample of the grease was placed into the cup of a penetration measuring apparatus (ASTM D 1403 test) and was subjected to a manual handling, the so-called 60-stroke working; the grease so treated exhibited a penetration of 241 (mm/10).
A grease sample subjected to the 10,000-stroke mechanical test exhibited a penetration, according to ASTM D 1403, of 250 (mm/10), which indicated a high mechanical stability. On the basis of such penetration values, this grease may be classified at the 3rd degree of consistency according to the classification of the National Lubricating Grease Institute (NLGI). On a sample of the grease, the thickening agent was recovered by means of repeated washings with 1,1,2-trichlorotrifluoroethane and by decantation in order to remove the Fomblin oil. The solid polytetrafluoroethylene, examined under an optical microscope, did not reveal particles having sizes greater than one micron.
The powder thus recovered was examined under an electron microscope in order to determine both shape and granulometric distribution of the primary particles.
The diameters of the particles varied from 0.13 microns (2% fraction) to 0.35 microns (0.5% fraction), the average diameter value being 0.19 microns.
The contour of the particles was round-shaped.
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powder of polytetrafluoroethylene or of a tetrafluoroethylene copolymer with another monomer having an ethylene type unsaturation, said powder obtainable by coagulation with an electrolyte of an aqueous latex containing polymeric particles having sizes comprised between 5 and 100 nm,
Abstract
Lubricating greases comoprising:
A) from 65.1 to 95% by weight of a (per)fluoropolyether oil having a viscosity at 20°C in the range 20-2,000 cSt;
from 5 to 34.9% by weight of powder of polytetrafluoroethylene or of a tetrafluoroethylene copolymer with another monomer having an ethylene type unsaturation, said powder obtainable by coagulation with an electrolyte of an aqueous latex containing polymeric particles having sizes comprised between 5 and 100 nm,
wherein the grease has a surfactant content lower than 20 ppm and a water content lower than 100 ppm.
Description
The present invention relates to lubricating grease compositions based on (per)fluoropolyethers, having low friction coefficients and reduced wears, particularly suitable to be used for example in bearings working at high speed in a wide range of temperatures.
(Per)fluoropolyethers having kinematic viscosities at 20°C between 20 and 2,000 cSt used as lubrificating oils, are known.
Greases obtained by said (per)fluoropolyethers by the addition of thickeners are also known, among which the most commonly used is polytetrafluoroethylene (PTFE) in powder.
In USP 4,472,290 it is described a process for preparing a grease based on a (per)fluoropolyether oil and PTFE in powder, in the form of aggregates having sizes from 1 to 200 micron, consisting in dispersing said PTFE in the (per)fluoropolyether oil by using a fluorinated surfactant. Said PTFE is obtained by tetrafluoroethylene (TFE) polymerization in aqueous dispersion and subsequent polymer separation from the aqueous medium. The greases obtained with this process show the following drawback, in particular at high temperatures: the surfactant contained therein decomposes thus modifying the good grease characteristics. In practice it is observed a corrosion of the bearing mechanical parts in contact with said lubricants.
In USP 6,025,307 it is described a fluorinated grease formed of: 15-50% of PTFE particles having sizes lower than 1 micron, 30-84% by weight of a perfluoropolyether oil and 0.5-10% by weight of a surfactant or of a dispersing agent having a perfluoroalkyl or perfluoropolyether chain. The preparation process of this grease is very complicate since it involves various steps:
gel formation by addition of a strong electrolyte, for example nitric acid, to a PTFE latex, obtained by TFE emulsion polymerization, through slow percolation of the acid in a gelification column containing the latex;
gradual gel neutralization by washing in column with slow flows of basic aqueous solutions having a decreasing concentration up to pH 6 and subsequent washings with water up to pH 7;
redispersion in water of the gel obtained by using a fluorinated surfactant;
addition of a light perfluoropolyether fluid to the above obtained aqueous redispersion and subsequent separation of the water and of the main part of the surfactant from the organic phase formed of the PTFE particles thus transferred in the light perfluoropolyether;
addition of the separated organic phase to a lubricating perfluoropolyether oil and subsequent evaportion of the light fluorinated fluid.
Said process, even though preparing greases having good lubricating properties, is disadvantageous, since it requires several steps and significant amounts of acid and bases and light solvents to be stripped. Further it is extremely difficult to obtain on an industrial scale a grease having a constant quality.
Besides in the grease obtained with this process there are high amounts of surfactant and water. The drawback of these greases is that said components, in contact with metal surfaces and/or at high temperatures, give corrosion phenomena. In practice the use of said greases is limited to applications wherein oxidizable metal parts are absent.
In EP 856,570 antiseizing pastes are described, prepared by addition to a perfluoropolyether oil having a viscosity between 20 and 2,000 cSt at 20°C of a PTFE in powder having molecular weight between 100,000 and 700,000 and particle size from 2 to 7 micron, the PTFE being obtained by irradiation with gamma rays or with electron beam of PTFE powder and subsequent milling.
These pastes preferably containing 50-60% by weight of PTFE are not suitable to be used as lubricating greases in bearings working at high speed due to the remarkable friction coefficient owing to the high solid content (PTFE).
It was therefore desired to have available (per)fluoropolyether lubricating greases containing low amounts of the thickening agent PTFE, having a combination of low wear and friction values, suitable to be used in bearings working at high speed in a wide range of temperatures, preparable with a simple, inexpensive and insutrially reproducible process.
(Per) fluoropolyether-based greases have been surprisingly and unexpectedly found, satisfying the above requirements.
An object of the present invention are (per)fluoropolyether lubricating greases comoprising:
A) from 65.1 to 95% by weight of a (per)fluoropolyether oil having a viscosity at 20°C in the range 20-2,000 cSt;
from 5 to 34.9% by weight of polytetrafluoroethylene or of a tetrafluoroethylene copolymer powder with another monomer having an ethylene type unsaturation, said polymers having a number average mclecular weight in the range 20,000-1,000,000, preferably 40,000-800,000, said powder obtainable by coagulation with an electrolyte of an aqueous latex containing polymeric particles having sizes in the range 5-100 nm, preferably 10-60 nm formed of polytetrafluoroethylene or of a tetrafluoroethylene copolymer with another monomer having an ethylene type unsaturation, having a number average molecular weight in the range 20,000-1,000,000, preferably 40,000-800,000, and subsequent drying,
wherein the grease has a surfactant content lower than 20 ppm and a water content lower than 100 ppm, preferably lower than 60 ppm.
The surfactant content of 20 ppm represents the sensitivity limit of the analytical determination as described in the characterization of the Examples.
The drying to obtain component is carried out at a temperture in the range 105°C-190°C, preferably 110-140°C. Generally powder particle aggregates are obtained having an average size between 10 and 30 micron.
The perfluoropolyether oils of component A) are selected from the following classes: (1) E-O-(CF(CF3)CF2O)m'(CFXO)n'-E' wherein:
X is equal to F or CF3;
E and E', equal to or different from each other, are selected from CF3, C2F5 or C3F7, one fluorine atom of one or of both end groups can be substituted by Cl and/or H;
m' and n' are integers such that the m'/n' ratio is in the range 20-1,000 and the product viscosity be between 10 and 4,000 cSt; the various units are statistically distributed along the chain.
These products can be obtained by photooxidation of perfluoropropene as described in GB 1, 104, 432, and by subsequent conversion of the end groups as described in GB 1,226,566; (2) C3F7O(CF(CF3)CF2O)o'-D wherein:
D is equal to -C2F5 or -C3F7, one fluorine atom of one or of both end groups can be substituted by Cl and/or H;
o' is an integer such that the product viscosity is within the above range.
Said products can be prepared by ionic oligomerization of the perfluoropropylenoxide and subsequent treatment with fluorine as described in USP 3,242,218; (3) {C3F7O-(CF(CF3)CF2O)p'-CF(CF3)-}2 wherein:
p' is an integer such that the compound viscosity is within the above range, one F atom of one or of both end groups C3F7 can be substituted by Cl and/or H.
These products can be obtained by ionic telomerization of the perfluoropropylenoxide and subsequent photochemical dimerization as reported in USP 3,214,478; (4) E-O-(CF(CF3)CF2O)q'(C2F4O)r'(CFX)s'-E' wherein:
X is equal to F or CF3;
E and E', equal to or different from each other, are as above;
q', r' and s' are integers and can also have the 0 value, and such that the product viscosity is within the above range.
These products are obtainable by photooxidation of a mixture of C3F6 and C2F4 and subsequent treatment with fluorine as described in USP 3,665,041; (5) E-O-(C2F4O)t' (CF2O)u'-E' wherein:
E and E', equal to or different from each other, are as above;
t' and u' are integers such that the t'/u' ratio is between 0.1 and 5 and the product viscosity is within the above range.
These products are obtained by photooxidation of C2F4 as reported in USP 3,715,378 and subsequent treatment with fluorine as described in USP 3,665,041; (6) E-O-(CF2CF2CF2O)v'-E' wherein:
E and E', equal to or different from each other, are as above;
v' is a number such that the product viscosity is within the above range.
These products are obtained as described in EP 148,482; (7) D-O-(CF2CF2O)z'-D' wherein:
D and D', equal to or different from each other, are selected from C2F5 or C3F7, one fluorine atom of one or of both end groups can be substituted by Cl and/or H;
z' is an integer such that the product viscosity is within the above range.
These products can be obtained as reported in USP 4,523,039.
The preferred perfluoropolyether oils are those of the classes (1), (4), (5) or their mixtures and are available on the market with the trademark FOMBLIN® marketed by Solvay Solexis.
Component is selected between the TFE homopolymer (PTFE) and the TFE copolymers with 0.01-1% by weight of a comonomer having an ethylene type unsaturation.
As comonomers having an ethylene type unsaturation, those olefinic, acrylic and styrene can be mentioned as, for example, ethylene, propylene, methylmethacrilate, (metha)acrylic acid, butylacrylate, hydroxyethylhexylacrylate, styrene, C3-C8 pefluoroolefins, as hexafluoropropene (H-FP) ; C2-C8 fluoroolefins containin hydrogen, as vinyl fluoride (VF), vinylidene fluoride (VDF), trifluoroethylene, hexafluoroisobutene, CH2=CH-Rf perfluoroalkylethylene, wherein Rf is a C1-C6 perfluoroalkyl; C2-C8 chloro- and/or bromo- and/or iodo-fluoroolefins, as chlorotrifluoroethylene (CTFE); CF2=CFORf (per)fluoroalkylvinylethers (PAVE), wherein Rf is a C1-C6 (per)fluoroalkyl, for example CF3, C2F5, C3F7, preferably perfluoropropylvinylether (PVE); CF2=CFOX (per)fluorooxyalkylvinylethers, wherein X is: a C1-C12 alkyl, or a C1-C12 oxyalkyl, or a C1-C12 (per)fluorooxyalkyl having one or more ether groups, for example perfluoro-2-propoxy-propyl; fluorodioxoles, preferably perfluorodioxoles; fluorovinylethers CFX=CXOCF2OR (MOVE) wherein R is a C2-C6 (per) fluoroalkyl or a C5-C6 cyclic group, or a C2-C6 (per)fluorooxyalkyl group containing from one to three oxygen atoms and X = F, H, preferably perfluoro-3,5-dioxa-1-heptene CF2=CF-O-CF2-O-CF2CF3 (MOVE 1) and perfluoro-3,5,8-trioxa-1-nonene CF3OCF2CF2OCF2OCF =CF2 (MOVE 2).
The preferred comonomers are perfluoropropyl-vinylether (PVE) and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (TTD).
The aqueous latex of polytetrafluoroethylene or of the tetrafluoroethylene copolymer with another monomer having an ethylene type unsaturation, used to prepare component, is known and is prepared according to what described in USP 6,297,334 herein incorporated by reference,
The preparation of the TFE polymer latex comprises the following steps:
preparation of an aqueous microemulsion of perfluoropolyethers;
feeding of the microemulsion in a polymerization reactor;
feeding in the polymerization reactor of demineralized water, reactor vent, addition of stabilizers, chain transfer agents, optional comonomers and reactor pressurization with TFE;
addition of the polymerization initiator;
discharge of the latex.
The microemulsion used in the latex preparation is described in USP 4,864,006 and USP 4,990,283.
As above said, the latex is coagulated and the obtained polymer particles are dried. The coagulation is carried out by addition of an electrolyte.
The electrolyte can be an inorganic acid or an inorganic salt. Among the acids, it can be mentioned nitric acid, hydrochloric acid, sulphuric acid; among the salts, it can be mentioned potassium nitrate, ammonium carbonate, magnesium sulphate, aluminum sulphate, potassium carbonate, calcium nitrate, sodium chloride.
Preferably nitric acid or ammonium carbonate are used.
As said the drying of the coagulated latex is carried out at a temperature in the range 105°C-190°C, preferably 110°-140°C, for a time between 20 and 60 hours.
A further object of the present invention is a process for the preparation of the invention (per)fluoropolyether greases comprising the following steps:
a) introduction of the lubricating oil A) in a mixer;
b) gradual addition in a continuous way or by steps of the powder of component to the oil;
c) slurry stirring;
d) discharge and refining of the obtained grease.
In step a), after the (per)fluoropolyether oil A) introduction in the mixer, generallly a degassing under vacuum at 60°C for 2 hours at 0.1 mbar is carried out.
In step b), the addition of the powder of component to the oil is generally carried out in at least 3 hours until reaching the desired composition.
In step c) the stirring is carried out in a constant way, for about 8 hours, under vacuum.
The refining of step d) is generally carried out in a three-cylindrical refiner.
The grease obtainable with this process has, as said, an amount of water lower than 100 ppm, preferably lower than 60 ppm and a surfactant amount lower than 20 ppm.
The greases of the present invention can be used as such or can be additioned with the known additives of the prior art, as, for example, antirust, antiwear, antioxidants, stabilizers.
The invention greases can be formulated depending on the amounts of A) and so to have different penetration degrees.
The penetration is determined according to the ASTM D-217 method and the greases are classified according to the NLGI scale from 000 degree, corresponding to a penetration value of 475 mm/10', to 6 degree, corresponding to 85 mm/10'.
The greases of the present invention result more stable, in applications requiring high temperatures, since the thickener is directly formulated with (per)fluoropolyether oil without using surfactants.
The greases of the present invention contain, the penetration being equal, compared with the known (per)fluorinated greases, a much lower amount of thickening agent (PTFE).
Unexpectedly and surprisingly the invention greases show very low friction coefficient values and a very reduced wear with respect to the known (per)fluorinated greases.
The invention greases are used in the lubrication of mechanical parts and their combination of very good properties makes them particularly suitable in the lubrication of bearings working at high speed and in a wide range of temperatures.
Even operating under these conditions, the bearings have improved peformances since the stress values are reduced and a lower heat generation is obtained (see the Examples, stress and maximum temperature reached).
Furthermore it has been found that the greases of the present invention, considering their low solid content, are applicable with significant advantages in the lubrication of microbearings, microgears, preferably in plastic, for example mechanical actuators, extending their life and significantly reducing the running noise.
The invention greases show furthermore a very low toxicity since they are formed of substantially stable and inert (per)fluoropolyether oils and PTFE.
Some Examples follow for illustrative and not limitative purposes of the invention.
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