CA1326616C - Perfluoropolyether derivatives in the form of an aqueous emulsion for protecting stony materials from atmospheric agents - Google Patents

Abstract

Abstract of the Disclosure Protecting marble, stone, tiles, cement, and analogous materials utilized in the building industry, from the action of atmospheric agents and pollutants, by applying onto the surface thereof a microemulsion of perfluoropolyethers, optionally provided at one end or at both ends or in the chain with functional groups capable of acting as anchoring agents to the substrate.

Description

The present invention relates to the use of perfluoropolyether derivatives in the form of an aqueous emulsion for protecting stony materials from atmospheric agents.
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1 3266 1 6 ~ -It is known that per~luoropolyethers impart remarkable water-repellent and oil-repellent properties to the surfaces ~--,:
o~ materials o~o which they are applied.
Furthermore, perfluoropolycthers exhibit a l~igh sunsen coefEicient Eor the air-~as componen~s, wherefore tlley permit a good passage oE the air ~hrough the surfaces oE the treated -~
materials.

i By virtue of these properties per~luoropolyethers are interesting as 1iquids useful to protect from a~mospheric -agents buildLng structures and, in ~eneral, articles made o~ -stone, marble, cement, tiles, ~ypsum, or wood.

Furthermore, the lower relractlve index o~

per~luoropolyetllers, which corresponds to a value Oe about 1.3 measured at 20C with light o~ a sodium-vapor l~mp, causes th~
treated article to retain its original appearance, avoiding optical inteLEerence phenomena which lead to a color alteration.

~; ~ This use o~ perfluoropolyethers was descrlbed ln an US patent No. 4,499,146. The perfluoropolyethers disclosed ,, in this U.S. patent applicatio~ where of the type having chemically inert end groups con~isting of perfluoroalkyl groups.

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It was observed that the presence of porosity in the material to be pro~ected led to a yhenomenon of slow absorption Or the per~luoropolyether ~ypes used so far, said phenomenon causing a more or less slow migration (depending on the type of porosity o~ the treated material~ of the protective liquid toward ~he innermost layers of the article. This results in a reduced eE~ectivenessl in the course of time, of the protection of the outer~ost areas of the treated article. While on particular materials, for example sandstones, this inward diffusion is sufEiciently slow ;-as to retain a pro~ec~ion stabili~y for a long time, in other cases (for example, tiles) this phenomenon causes such a decrease in the surface protective effect as to require, in the cour~e of time, ~urther sur~ace treatments, although the protection of the underlying layers re~nains efeicacious enough to remarkably slow down the alteration phenomena.
From US patent No. 4,745,009, lt is known that it is possible to obtain a permanent protection oE the surface area of the above mentioned materials ie perfluoropolyether derivatlves with eunctional end group5 capable Oe eorming chemical and/or physical bonds with ~he substrate are used as :: . . .
~ protective agents or as coadjuvants. Such functionalized end . .
groups become flxed to the substrate to be protected, thereby reducin~ the per1uoropolyether mobillty and increasin~ the duration of the protective efect on the treated sur~ace.
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~- 1 3266 1 6 All the systems described in US patent Nos. 4,499,146; 4,745,009 and 4,746,550 ~ -cornprise, as an essential component, a solvent, in particular a fluorocarbon or a chlorofluorocarbon. -The applica~ion o~ these compounds to the substrate i5 preferably carried out by using l,l/2-trifluorotrichloroethane in admixture with other organic solvents containing from 50 to 80% by weight of the pereluoropolyether productsO ~pplication is by means of atomised liquld jet spraying, either with compressed air or without compressed air, or by means of some other appropriate method.
The amount o~ perEluoropolyether protective agent utilized is largely dependent on the porosity of the material to be treated, and varies Erom 10 y/m2 to 300 g/m2 as the ~ -substrate porosity increases.
From the viewpoint o~ ecology and environmental protection, the advantage which would result from the use of qyqtems Eree from chlorofluorocarbons, and optionally in the complete absence of volatile organic solvents, is evident.
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In accordance with the present invention, it has now, sueprisingly, been dlscovered that it is possible to att~in this and further advantages in the protection of works and ~;
articles made oE stone, marble, cement, gypsum, and wood by ;~ ,'' ~ '' , using, instead of perfluoropolyethers as such or in chlorofl~orocarbon solutions, aqueous microemulsions of functional perfluoropolyethers.
The term "microemulsion" is generally used to designate products macroscopically consisting of a single .i .
transparent or opalescent and optically iso~ropic liquid phase comprising two immiscible liquids and at least one surfactant, wherein one o~ the two immiscible liquids is dispersed in the other liquid in the form of droplets having diameters approxi-mately ranging from 50 to 2~000 A~
In principlel the presence o;E particles having greater or smaller sizes up to the limit of khe molecular dispersion cannot be excluded. Furthermore, compositions are possible in which the two liquids are interdispersed as bicontinuous tri- ;
i dimensional films, or in which the two immiscible liquids are i co-qolubilized at a molecular level.
, . - , . .
!l :, ' ':' Such products spontaneou31y form by simple mLxing of ., :,- ~ .- .
i the components when the lnterfacial tension between the two -: lmmiscible liquids decreases to values close to zero and are . --I indeinitely stable over a certain temperature range. ~ :1 : 1', ' ' .' ~':
In connection with the present invention, the term "microemulsion" has a broader meaning, and comprises also non~

: ll optically isokropic systems ~ . birefringent) characteri2ed 1, ....
I by a liquid-crystalline type o orientation o~ the components.

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` 1326616 There is an advantage in having available microemulsions instead of emulsions~ as the former do not :-require a high dispersion energy for obtaining them; are ~-regenerable and indefinitely stable in the long run; and while .
the emulsions must be prepared taking into account the order of addition of the components, they supply a high dispersion .
energy and have a limited stability in the course of time.
Furthermore, when they give rise to a ph~se separation due to aging, oEten they cannot be restored to the original emulsion .:
state even if the amount o~ high energy necessary to obtain `.
them is employed.

The microemulsions utilized in the present invention may be of the oil-in-water type or of the water-in-oil type, and preferably of the o/w ~oil-in-water) type, and consist of perfluoropolyether chain compounds having end groups at least - .
In part of the functionalized type, and optionally peroxide bridges in the.chain, and compo~ed of mixtures of products of :
diEferent molecular weights, of a perfluorinated surEactant -and/or a co-surfactant such as an alkanol with 1-1~ carbon ~ ;.
atoms, and of an aqueous phase optionally comprising an ..

electrolyte and/cr an inorganic water-soluble base. The microemulsions to be used according to the present invention may be prepared by ollowing the procedures indicated in US patent No. 4,990,283.

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'';'~ '' ' ' The functional groups may also be present on branches of the perfluoropolyether chain, as described in ~uropean laid open pate~t application EP-A-244,839.
The perfluoropolyethers of the present invention may be prepared by photooxidation of C2F4 and C3F6, without any -further thermal treatment,.and may have peroxidic bridges in the chain.
One may also utilize perfluoropolyethers prepared hy means of a process Eor photo-o~idizing in the liquid phase with molecular 2 a mixture of C2F4 and/or C3F6 and a ::
perfluorinated conjugated diene, with subse~uent decomposition oE the peroxide groups contained in the photooxldation product by a thermal treatment in thep~ssible presence of UV-rays, for example those having the forrnula;

R~fo(cF2lFO~ FXO)n(cF2-fFo)pR'f or c~3 COF
' ''.'.' R'fO(C2F40lm(cF2o)n(cF2fFo)p f -:

: COF :

: where m, n and p are integers, X = F or CF3, and Rf and R'f may be functional groups or perfluoroalkyl having from 1 to 3 ~: carbon atoms. :;

: 7 ; ~- -~ . , 1 3 2 6 6 1 6 `:
The perfluoropolyethers utilized according to the present invention are well known in the technical and patent literature cited and are generally obtained as mixtures of compounds having the necessary perfluoropolyether structure, a molecular weigh~ varying over a certain range, with possibly -different end groups.
The mean functionality of the perfluoropolyethers ranges from O l to ~, preferably from O.l to 2, and more -~
preferably from 0.2 to 1. ~
The functional groups present in the PFPE chains may be represented by the formula:

CFX-~B)3-Z~ . ;

where X is F or CF3 and where ~ a 0 or 1, B is a divalent or polyvalent linking ~ -~
~: hydr~carbon radical, in particular an alkylene or a ~ .
cycloalkylene or an arylene radical, having up to 20 carbon atoms and preferably up to 8 carbon atoms, K ranyes from 1 to ~; 3~ and preferably iq 1, and Z is the actual functional group.
"Functional group Z ll means a group capable of forming a~ chemical and/or physioal bond with the aforesaid material to :
be protected, and selected from: :

: :

~ - S

1. ~ . .

r~

-- a non-aromatic, non-fluorinated organic radical containing electronic doublets-donor heteroatoms, or an aromatic radical, either containing or not containing heteroatoms, capable of giving rise to coordinate bonds or to chain transfer bonds, thereby causing different kinds of adsorption phenomena on the substrate;
-- -CoNR2R3, -COOR where R i~ H or an alkyl group having from 1 to 8 carbon atoms, or an aromatic alkyl aromatic group such as ~enzyl;
-- -OH, -COF; -~- -NCO, -NHR~ -COQ; -CO-CF3; -C(OH~2-CF3; ~.
~- SO3H; ~
-- polyoxyalkylene-OH; and ~.
-- quaternary ammonium.
The pref~rred functional groups are: -ca-cF3;
-C~0~2-CF3; -COOH, -OH, -polyoxyalkylene-OH, and quaternary ~ ~-ammonium groups. The acid end group is preferably salified.
As starting products, it is also possible to use perfluoropolyethers with -COF or -SO~F end groups which, during the preparation of the microemulsion, hydrolyze to -COOH and -SO3~ groups.
The mean molecular weight of the perfluoropolyether chain ranges from 500 to 10,000, and pxeferably from 2,000 to 6,000.

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1 3266 1 6 -:

The perfluoropolyethers utilized in the present : ::;
invention may also contain, besides the above-mentioned :
functional groups, perfluoroalkyl end groups.
The perfluoropolyethers utilized in the present . - :
invention are those consisting of ~luorooxyalkylene units , -: , selected from the followi~g groups:
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( IF-cF;~O); (CF2CF20); (CF20) (fFO) (CF2-fFO); (CF2CF2CF20);
CF3 ~F3 CF3 ~nd (CF2CF~CH20); and in particular belonging to the following classes: : .
','; ;' ', ,- ' , ':: ~,: . .
(1) RfO( CF2-1FO~ n(7FO)m (CF2)pO2R f : ~

: CF3 CF3 ` : -:
',:":~

: with a random distribution of the perfluorooxyalkylene , units, where~m, n, p and z hava such mean values as tomeet the ..
above9aid requirements conCerning the mean molecular ~ -weightS z i8 zero or an integer where Rf and R'f, either alike or dife~ent from ::
ea~ch~other, may be perf luoroalkyl ènd groups optionally ~ ;
con~tain:ing l:to 3 carbon atoms or ~unctional end groups of ; :
the type; CFX~B)J-ZK, where B, J, Z and X are as defined "~
hereinbefore; .. .. ~-: ~

, . ...... .

'i~ '! ' ~ ' (2) RfO(CF2CF20)n(CF20)mR'f with a random distribution of the ;~:
perfluorooxyalkylene units, where m, n have such mean values as to meet the abovesaid requirements as to mean molecular weight; where Rf and R'f may be perfluoroalkyl end groups optionally containing 1 to 3 carbon atoms or ~:
functional end groups o~ ~he ~ype CFX(B)J-Zk, and where B, J, Z and K are the same as defined hereinbe~ore;

where m, n, p, o and z have such mean values as to meet the abovesaid requirements (z is as a~ove) as to mean molecular weight;

(4~ R~O ~; -CF n -R'z where n has such a mean value as to meet the abovesaid requirements as to mean molecular weight; ~: -5) R~O~CF2CF20)nR'f where n has such a mean value a~ to meet : ~-the abovesaid requirements as to mean molecular weight; :.
and .
,, , '~'''''' ' - 11 - .....

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"-^` 1326616 f ( 2 2CF2)n~ f or Rfo(cll2cF2cF2o)nR~ where n has such a value as to meet the above requirements as to mean molecular weight.

Perfluoropolyethe~s oE class (1) are marketed under the tradename Fomblin~Y, those of class 12) under the :~:
teadename Fomblin~Z, all Oé them being produced by Montedison ~ -of Italy. Commercially known produc~s of class (43 are :~

Krytox ~ (DuPont).

The products o~ claiss (5) are deiscribed in U.5. patent No. 4~523/039; those of class ~6) are described in European patent No. EP 148/48Z to Daikin.

The products of class (3~ are prepared accordlng to U.S. patent No. 3,66S,041. Suitable also are the perfluoro-polyethers desc~ibed in U.S. patent No. 4,g23,~39 or in J. ~m.
Chem. Soc. 1')85, 107, 1195-1201.
The products of classes ~1~, (2) and (3), which are obtained through photochemiaal oxidation processes, are util1zable as roagh prodocts Oe the photooxidation process, ~:
wh~ch contain in the chain peroxide groups -00- inserted between the perfluorooxyalkylene units. :~

Perfluoropoly~thers suitable for preparing :~
mlcroemulisions according to the present invention include those descri~ed in European laid open patent application EP-A-244,830, which comprlse functional groups of the above-indicated type 12 ~;.

132~gl6 arranged along the chain and Eunctional or perfluoroalkyl end groups.
The microemulsions to be used in the present invention are preparable according to methods described in US

patent No . 4, 990, 283 . An _ :
essential ingredient is an ionic or non-ionic fluorinated .
surfactant~ In particular, the following may be cited:
(a) perfluorocarboxylic acids having from 5 to 11 carbon atoms and the salts thereof;
(b) perfluorosulphonic acids having from 5 to 11 carbon atoms and the salts thereof;
(c) the non-ionlc suractants indicated in European patent application No. 51,526 and consisting of a perEluoroalkyl chain and of a polyoxalkylene ;~
hydrophilic head~
:~ ~ (d) mono- and bi-carboxylic acids derived from ~ .
: ~ perfluoropolyether~ and the ~alts thereof;
(e) non-ionic surfactants consisting of a ~ perfluoropolyather chain lin~ed to a polyoxyalkylene : : ~ chain; and :::;
(f) per~luorinated cationic surfactants or cationic~ ~.
sur~actants derived ~rom perfluoropolyethers having ::
: : 1, 2 or 3 hydrophobic chains.

~ ~ ,';''', ~ 3 ~ 6 6 1 6 As a co-surfactant one may use a hydrogenated alcohol ~ -having from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms, or a fluoroalkanol.
:.
The amount of perfluoropolyether protective agent to be used varies as a function of the nature of the material to :,' be treated, in particular its porosity. The total amount of perfluoropolyether ranges from 7 g/m2 for low-porosity materials to be protected to 100 y/m2 for materials exhibiting a higher porosity.
The following examples are given merely to illustrate the present invention, without, however, being a limitation .
thereon.
Example 1 ~ -~

Three marble test pieces were prepared measuring 8 x - ;

6.5 cm, characterized by different porosities. Each test ~ .
piece was super~icially treated with a microemulsion having ~; ~
; ,-, :-- ~ .
the ~ollowing composition: - ~
~ ~, s ,' . ~ ~ .
37.8 g of a rough perfluorop~lyether belonging to i, cla~:(1) containing -CF2-COF end group6 having a mean . : :
~: il functionality equal to 0.46 and a viscosimetxlc aYerage moleGular weight of 4,6:00, containing peroxlde bridges (peroxide power 'j (P.OO) = 1.02 ~, and consisting of a mixture of ~ ~
, ~ .
;, . . .
polymers having different molecular weights, ii ~ : :: ' .
6.5 ml of a solution at 10% by weight of NEI3, -- 111 ml of doubly distilled water, ,: ,~
;: :

,, .

11 ' "::."
, . . .:
, 132661~

-- 1.5 ml of an acid having a perfluoropolyether structure belonging to class (1) where Rc is CF3 and R'F
is CF2-OOOH and an equivalen~
average molecular weight e~ual to 668, and n. 5 ml of -.
an acid having a perfluoropolyether structure belonging ~o clas5 (1) where R~ is CF3 and R'f is CF2-OOOH
and an average : -molecular weight e~ual to 367, and -- 21.5 ml of t.butanol.
The composition by weight of the system was the .;;:
following:
.
- aqueous phase 66.7%
- alcohol 9.8%
-- fluorinated surfactants 2.0%
-- rough perfluoropolyether 21. S~
This microemulsion was applied by means of a brush or a .
~: ~ compressed air sprayer in such manner as to cause a total :;~
: , amount o~ ~luorinated componen~s e~ual to about 20 g/m2 to be ; deposited onto the test~piece surface. .~ :
: ~ : On the test pieces, the amount of absorbed water was , messored after 4 days. Such amount was compared with the . ~;~
am~unt absorbed by four equivalent untreated test pieces, ::~
utilized ~s:a check or control. -~ :
The measurement o~ water a~sorption was effected by . .
, cau~ing tQ adhe~e to a face of the ~:est pieces a rubber -j: . .:...... .
~ cylindrical gasket lnto which a measu~ed amount of doubly - ~. :;i ~., ~ .
~ distilled water was introduced. At pre-established time , ~
, ~ .: :
': ,, ' .,,. '' :', ,' '.',,''''':. ':

1' .,.',,.' ~326616 intervals the test piece surface was dried and the absorbed water amo~nt was determined by weighing.
The data obtained are reported hereinafter; the absorbed water is expressed in microliters/cm2 of surface.
Table 1 . _ , ~ .,, , . ~
Test p1ece l Test plece 2 Test piece 3 mean porosity brush mean porosity spray lcw porosity spray T~e ~ appl c tion application ~ , __ _____ Treated Untreated Treated Untreated Treated Untreated -~-~ . .__ __ _ . ........ , ~
4 hours5.5 38.2 0 38.2 0 5.5 7 hours11.0 46.l _ 46.1 0 8.2 ~-''' ~. -: :
The results of this example prove that, for all the test -~
pieces tested, the water absorption clfter the surface -~
treatment with a microemulsion based on rough : :.- - -perfluoropol~ethers is considerably reduced as compared with .
, - ~ .
- the corresponding untreated test pieces.
:: .-, : -From an asbestos cement sheet, two te~t pieces measuring 15 x 24 cm were obtain~d. One of the two test ieDes was left as such as a check, while onto the surface of I, the other test piece, by means of a compre~sed air sprayer, ; there~was applied a microemulsion having the following composition: ~

. . ~ . . ~ :

: 13~616 .~.

-- 11.8 g of a rough perfluoropolyether belonging to class (1) hydrolyzed by treatment with hct dilute : .
H2S04, having an average CF2000H functionality equal to 0.6 and a viscosimetric average molecular weight of 4,000, ':
containing peroxide bridges and consisting of a .~
;
mixture of polymers having different molecular .. ~:
.-,.:: :-weights; .` ~;
-~ 2.55 ml of a solution at 10~ by weight of NH3; ~ : :
. ' " 7 .
-- 31,0 ml of doubly distilled water; .-~
-- 5.8 ml of isopropanol.
. - : .
The composi~ion by weight of the system was as ~1~
. ~,... .
:, ollows: . : ;
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,, :: , -.
~ - a~ueous phase 67~
~ ~ :
alcohol 9.3~
rough perfluoropolyether 23.6%.
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1 ' . : - . . ~, . .
~ he total fluorinated components amount deposited on the test .. ~
, .. :. ~
' piece was equal to about 7 g/m~
Water absorption me~asurements were carrled out aftsr -~
th:ree months by `using a method analQgous to the one described - -::-1n~tne pr~ecedlng example. : ;
After;2 hours, ths amount of wster absorbed by ths untreated test piece was of 41.3 mg/cm2, while ~he amount of ;~:
ater ab`sorbed by the:treated test piece fell to 8.7 mg/cm2.

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1 3266 t 6 Two Carrara marble test pieces were utilized having composition and porosity llke those of the test piece described in Example 1 of Italian patent application No.
19,626 A/85. One of the two test pieces was superficially :: ¦
treated with a microemulsion ha~ing the following composition~
-- 12.6 g of a rough perfluoropolyether belonging to -class (1), having an average functionality :~
due mainly to cF2ooF e~l to 0.46 and a viscosimetric average molecular weight ~; :
equal to ~,600, containing peroxide bridges . (P.O. - 1.02) and consisting of a mixture of :, polymers having di~ferent molecular weights; .

- 3.7 ml of a solution at 10% by weight of NH3;
-- 31 ml of doubly distilled water; : - --- 5,73 ml of t.butanolt -- 1.71 9 of an acid having a perfluoropolyether structure belonglng to class (1), where R~ is CF3 and R'f ls CF2COOH, an a~erage molecular welght equal to 668, and the following by~
. - '~
~ li weight composi~ion~
i '' water:phase 63.40% .-~ :
al~ohol 10.47%
fluorinated surfactants 3.12%
rough perfluoropolyether 23.10%. :~ .

',, - 18 - :

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The microemulsion was applied by means of a brush. It was not possible to deposit the same amoun~ (30 g/m2) as indicated in Example 1 of the above-cited Italian patent application, because the test piece did not absorb ~n amount .
of microemulsion higher than 7~7 g of total fluorinated ;~

compounds/m2. '- . .
The water absorption measurement was carried out in the same manner as is described in Example 1 of the present ~
application. In the treated test piece, the absorhed water ~ ~ -amount/cm2 was equal to ~ero up to 30 minutes; in the untreated test plece the absorbed wat:er amount measured after :~
30 minutes was, conversely, equal to 7.6 microllters/cm2 ~ ;

i , . . .
Two mar~le ~est pieces like those in Example 3 were .; ;
! utilized and having a mean porosity. One of the two test : l pieces was treai~ed on the surface with a Freon solution at 50% -~
by weight o~ a rough perfluoropolyether belonging to class having an average functionality due mainly to CF2CO~ equal ~-. to 0.57 and a .l viscosimetric average molecular weight equal to 4,000, ;
containi:ng peroxide bridges tP.O. = 1 02% by weight) and il . , i, ~ . . .. .
consisting of a mixture of polymers having different molecular weights. ~he application wa~ carried out by means of a brush;
~ ! ~ . ' "
the amount o fluorinated compound deposited on the tes~ piece ~. .

~urface was of 7.g g/m2. ~ .
. .
`' ', :
! .
- 19 - :

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1 ~2661 6 The other test piece was left as such, as a check.
Water absorption measurement was carried out accordin~
to the procedures described in Example 1 of the present ~
application. In the treated example, the amount of water ,;
absorbed expressed in microliters/cm2 was equal to 4.7 after 30 minutes, while in the untreated test piece the amount of ,~
water absorbed after the same time was 7.6.
From a comparison of the data of Examples 3 and 4, it , is apparent that (the amount of fluorinated compounds pre~ent ~ ~
on the test piece surface being equal) the water absorption ~ ''"
was equal to zero when the microemulsion was used (Example 3), ~' while it was reduced by about 60%, referred to the test piece as such, when a ~reon solution o~ the fluorinated compound was , ~ ' used.
~ '.'' ;.-',~.:
- , Two Siena brick test pieces ,having a mean porosity of 40~ were treated wi~h a microemulsion having the following compo~itlon~ , g of a perfluoropolyether cr~/tainmg -CF2COOH ~'' and CF2COCH3 end groups, belonging to class (1), having a vlscosimetric average molecular weight equal to ; ' ' 2,080 and an equivalent average molecular weight ~ ~ , ''' equal to 2,860, consisting of a mixture of polymers ~''' having different molecular weights; ' , ~,: '', - .. ' :.
~, ,' ,-.
,, ,, - 20 - '' '''"' 13~61~ ;

-- 7 ml of a solution at 10% by weight of NH3;
-- 49.5 ml of do~bly distilled water;
-- 5.4 9 of an acid having a perfluoropolyether structure belonging to class (1) where Rf is CF3 : :~
: and R'f is CF2GOO~ and an average molecular weight equal to 668, and 8.1 9 of an acid .
having a perfluoropolyether structure and an , equivalent average molecular weight equal to 361 exhibitlng the following composition by weight~
., . - . .:
-- aqueous phase 64.12% -1 -.
-- fluorinated surfactan~s 14.5S% ; :
! , :
-- rough per~luoropolyether 21.33%.
The protec~lve efflciency was measured by means of ;
. water absorption tests on the same test pieces before and ~
after 2 and 25 days after the treatment~ "Percent protective ~ ~.
~:e~ficiency" means the ratio between the difference of water .-.. ..
a~orbed beore and after the treatment and the amount of -~
water absorbed by the untreat~d matérial, multiplied by one hundred. The amount of water absorbed by a test piece was measured in aacordance with th~ me~hod proposed by VNESC0- .
BILEM ~International Symposium on Deterioration and Protection o~5tone Instruments, Paris, S-9 June 1978l Vol. 5r Test , ~ ; . . . . .
~ .4). The data obtained are reported hereinafter: ~1 :: :
il ~. ,:-. ' .
, : , ' .. '.' ,i ' ,. ' .~: .
- 21 - : :.:.:
: ," ,',.
'..~'."' 1 ~ 2 6 6 1 6 ~ . . .
PFPE amount deposited Protective_eficienc on the test pieces ~q/m2)after 2 days after 25 days _ ~ _ _ _ _ 50~ 45 68% 61 96% 80 . ~ .

~i ':
Utilized were ~wo asbestos cement tes~ pieces measuring 15 x 10 cm. One of ~hese test pieces was kept as a : -check, while the other test piece was brush~treated with a microemulsion prepared by adding to 25.44 g of a rough perfluoropolyether belonging to cla~s (1), hydrolyzed by treatment wi~h hot dilute H2SO4, having an equivalent weight equal to 10,000 with respect to the acid gro~p~ t(cF2cooH) and a viscosimetric a~erage molecular weight equal to :.

4,600, containing peroxide bridges ~P.O. = 1.02~, and consi~ing of a mixture o polymers having different molecular -~ .
weights, neutralized with l.S ml of an ammonia solution at 10% ~.
by weight o~ NH3, 76.4 ml of triply distilled water, 14~4 g of `~ ~
" : -, ~ ~ isopropanol, 2.16 g of a carboxylic acid, and having an , :~ ~ `; equivalent average weight equal to 668 and a : perfluoropolyether str~cture belonging to class (1) : -where R~ is CF3 and R'f is CF2-aX~. ~ .- .
system was a obtained characterized by a single , I, .: ~.:.:: .:
.~ limpid, transparent phase, which was indefinitely stable at a : temperature from 20 to 80C.
:, 22 . ! ' ' .

1~26616 -:

The composition by weight of the system was the ~ ~ -following: :.
-- roush perfluoropolyether 21.2% ~-~
: . .
-- aqueous phase 64.9%
:
-- fluorinated surfactant 1.8% -:; :. :

-- alcohol 12.1~
.. .
The total amount of total fluorinated componen~s .-deposited on the test piece was 6.4 g/m2.
The obtained data are reported hereinbelow. ;- :

!! :
;' ~G~_ . ~iC ~ v ~ ' " ~'. . ' ,-: :
15 minutes 1 hour 10 days .~ .

61.5~ unchanged un~hanged, .
" ' A low~porosity marble test piece was kept as a check. I `.
The surfa~e Oe a seçond like te6t piece was brush-treated with a p~rotec~ive agent consiqting of a microemulsion prepared by ~;~ i adding to 2S.44 g of a rough per1uoropolye~her belonging to ~:
cl~ss (1), hydrolyzed by treatment with hot dilute H2SO4, having an ~ .
average e~uivalent weight of 10,000 with respect to the acid ,. ~.
groups ~CF2COH) and a viscosImetric: molecular w~ei~ht equal to 4,6000, . . -'i corltaining peroxide bridge ~P.O. = 1. 02), and composed of a m~Xture of polymers havlng di~ferent mole¢ular weights, neut~alized with l.S ml of an ammonia solution a~ 10~ by -:

,j , : : ~ -, weight of NH3, 76.4 ml o~ doubly distilled water, 14.4 g of ,.. -~:

'"'~ :'''"~
:::

isopropanol, and 2.16 g of a carboxylic acid, and having an average equivalent weight equal to 668 and a perfluoropolyether structure belonging to class (1) where R~ is CF3 and R'f is CF~X~.
The resulting system was characterized by a single limpid, ~ransparent phase, which was indefinitely stable at a temperature from ~0 to 80C.
The composition by weight of the sy~tem was as ~ollows: --- rough per~luoropolyether 21.2%
-- aqueous pha~e 64.9%
- fluorinated surfactant 1.8% ~ ~
. -- alcohol 12>1%. ~-,' The amount of total 1uorinal:ed components deposited on the test piece was equal to 19.1 c~/m27 The data obtained are reported hereinafter. ~:
; Percent Protective Efficiency ::
: .
1 hour 7 hours ~ :
,' ' ,',. ' . .
72~2% unchanged.

::
Two high-porosity marble test pieces were utilized.
The first one was kept as a check, whil~ the second one was treated with a mlcroemulsion prepared by adding to 25.4~ g of :, a roagh per~luoropolyether belonging to class (1), hydrolyzed by treatment with hot R2SO4, having an average equivalent ---weight of 10,000 with respect to the acid groups (cF2ax~l) and a " ' : ' - 24 - : .
'I , ~, ' . : '; "
'. ' :, .

....
viscosimetric molecular weight. equal to 4,600, and containing peroxide bridges (P.O. = 1.02), and consisting of a mixture of polymers having different molecular weights, neutralized with 1.5 ml of an ammonia solution at 10% by weight of NH3, 76.5 ml of doubly distilled water, 14.4 g.of isopropanol, and 2.16 g .. .
o~ a carboxylic acid, and having an average equivalent weight~ -, , .- .
of 668 and a perfluoropolyether structure belonging to class : :
(lj where Rf is CF3 and R'f is CF2~X~.
The system obtained was characteriæed by a single : - , .
limpid, transparent phase, which was indefinitely stable at a .
temperature from 20 to 80C.
The composition by weight of the sy~tem was as .
~ollows:
:, -- rough perfluoropolyether 21.2% ~ ~ .
, -- aqueous phase 64.9 fluorinated surfactan~ 1.8~
.', . ;':-.
alcohol 12.1~.
The amount of total fluorinated components deposited .:~
on the test piece was equal to 20.2 ~/m2. -1 1 : ~. : -, Tb~ perGent protective efficiency measured after 1 . - .;
~ ;, hour exh~bited a value o~ 88.4~. Such value was unchanged .
! ! a~ter 7 hour~.
; i , :., ., .; , 1 ~ , ~-. :.
~ ... , --.. :
" -. ' - 25 - ~:
,~

1326616 :

Example ~ .
Four sandstone test pieces having a porosity of 8.5~ ;
and measuring 50 x 50 x 20 cm were used.
Test pieces 1 and 3 were not treated; test pieces 2 .
and 4 were treated by applying, by means of a brush, a . ~
: microemulsion hav.ing the following composition: --- 1.55 g of a rough perfluoropolyether belonging to ..
class (1), hydrolyzed by treatment with hot dilute H2S04, and having an average equivalent molecular weight equal to 2,860 wlth respect to ac1d groups (CF2COCH)and v~cos ~ tric ~ -molecular weight equal to 2,080, consisting of a ~
mixture of polymers having d:Lfferent molecular ~ :
weights;
0.5 ml of an ammonia solution at 10~ by weight of NH3;
9.4~ 9 o~ doubly distilled water; and ~ .
2.2 g of isopropanol. .; ~-.
The resulting sy~tem was characterized by a single . .
:~ ~ ;limpid, ~ransparent phase, indefinitely stable at a temperature from 25 to 75C. ~he composition by wei~ht of .; the~6ystem wa as follow :
rough perEluoropolyether ~ 11.3~
aqu60us~ phase 72.7% ~ : :
- a}cohol . 16~0~o ' . ' .:

,: i .: .. :

' ! i ::
1'1 ' ' ~'''''', '! :: .. .

,,~..., -...
The total amount of fluorinated components deposited on the test pieces was 30 g/m2 for test piece 2 and 40 g/m2 ¦-for test piece 4. ~ -The treatment eficiency was evaluated on the basis of the amount of water absorbed by ~he various tes~ pieces in 60 j:
mlnutes and is expressed by the percent ratio of the difference between the amount of water absorbed by the untrea~ed test piece and the amount uf water absorbed by the . - .
test piece afl:er it was treated, to the amount of water absorbed by the untreated test piece.
The ~est wa~ carrled out by applying to a ace of the :.
~est pieces a d~vlce consisting o~ a glass cylinde~ illed with water and connected to a graduated micropipette which permitted measurement of the water amounk a~sorbed by the :~
contact surface of each test piece. The device i~ described - -~
In the document published by UNESCO-RILEM PEM No. 78,182.
he absorbed amount of water was read at pre established intervals of time and the resulting value ii ~ . - :' .:
expressed in:g/cm2 of surface.

æ~ Absorbed wa~er amount Percent protective : ~::
efficiency 0 . 0 10 2 0.0~21 7g.0 3 0.0140 0.0020 86.0 .,' ''' :.

. .
Example lO
Four Siena brick test pieces having a porosity of 40 and measuring 50 x 50 x 52 cm were utilized. The first test piece was not treated; the other test pieces were brush-treated with a microemulsion having the following composition:
-- 18.8 g of a rough perfluoropolyether hydroly~ed by :~
treatment with hot dilut~ H~S04, belonging to clas~
having an average equivalen~ molecular weight of 2,860 .:

wlth respect to the acid groups (CF2~X~) groups and a :~ :
viscos~tric average molecular weight equal to 2,080, consisting of a mixture of polymers having different molecular weights; ~:
-- lO ml of an ammonia solution at 10% by weight o NH3;
-- 49.5 ml of doubly distilled water; ~::
-- 5.4 g of a carboxylic acid having an average ~ -.
. .
equivalent weight of 6~8 and 8.1 g of a carboxylic acid having an average equivalent weight of 361, each o~ them having a perfluoropolyether structure and belonging to class (l), where Rf is CF3 and R'f is C~OOOH. ;
The resulting system consisted of a single llmpid ~ :
phase, which was stable at a temperature from 25 to 75C, the -:
erceDt composition by weight of which was as follows: ~:
rough perfluoropolyether 21.3%
aqueous phase 64.1% ~ - ;
fluorinated surfactants 14.6%. ~- ~
., ,~ '''' .

.',.. ,,~
!
, j - :
. ~! :` -The amount o~ total fluorinated components deposited on the test pieces was 30, 60, 90 g/m2 for test pieces 2, 3 and 4, respectively.
The treatment efficiency was evaluated according to the method described above in Example ~

,,,.,,-~. .
_ _.. . . .
.. .: .. ..
Test ~iecebsorbed wa~er am _nt Percent protective . ::.
(g/cm ) efficiencY

1 2.5 2 ~.37 45.0 .
3 0~7 61.0 ~50 81,0 -~

Example 11 :
'I Six Vicenza s~one test pieces (biocalcaselenite with a ~ .
porosity of 30%1 were used. Test pleces 1 and 4 were not ~
-: -treated~ ~est pieces 2 and 3 were brush-treated with a . mic~oemulsion having the composition indicated above in ,... .
Example 10; test pieces 5 and 6 were treated by applyin~ by means of a brush a microemulsion having the following .:
compo~ition~
~.

~ 1. '.',':', :: i. :.~ .. , :

.,: . , - 29 ~
.. . '' . .

37.9 g of a rough perfluoropolyether belonging to :~
class (1), hydrolyzed by treatment with hotdilute H2SO4, having an average equivalent molecular weight of .
10,000 with respect to the acid groups (CF2oX~)and a viscosimetric average molecular weight equal to 4,600, ~ -containing peroxide bridyes (P.O. = 1.02) and :
consisting of a mixture of polymers having different .~
~ ., -molecular weights; ~:
-- 6.5 ml of an ammonia solution at 10% by weight of NH3; - :--- 111 ml of doubly dLstilled water; ` - .
-~ 17.2 g of ~er.butanol;
-~ 0.9 g o~ a carboxylic acid having an average .
equivalent weight of 361 and 2.7 9 of a carboxylic acid having an average equivaleDt weight of 668, each of them having a per~luoropolyether structure and : ~.
elongiog to class ~1). where Rf is CF3 and R'f is CF2~X~. ':: ;
: ~ The resulting system was characterized by a sin~le . ~:
limpid phase, stable a~ a t~mperature from 25 ~o 75C and `.
hav~lng the following percent composltion by weight~
rough perfluoropolyether21.5~
- aqueous phase 66.7%
alcohol : ~ 9.8%
fluorlnated surfactan~t~2.0%. . -`~-i ! . .: ~
'' ~ ' ,.. ; .:

~ : . ~ 30 - ;
~ -: ;
' 11 , `I '',.".',.', 13~661~
,, .
The total amount of fluorinated components deposited on the test pieces was 90 g/m2 for test pieces 2 and 5 and 120 - : .
g/m2 for test pieces 3 and 6. The treatment efficiency was evaluated aocording to the procedures described in Example 9.

Test ~iece Absorbed wa~er amountPercent Protective .-- -(g/cm ) efficiency ...
. .. . - . .
1 0.940 - -2 0.297 68.0% ~ :
. 3 0.141 85.0~
i 4 1.200 ~ ;
- . .
0.750 38.0~ .~
6 0.220 65~0% . .:

~ . ~ , ,. -: ."'' : Four cement A test pieces (porosity: 18%) and two . ~ , cement B test pieces (porosity: 25%) were utilized. A test piece of each type of cement was left as such as a check; the :~.
~ ~ ~ other test pieces were brush-treated with the microemulsion ; ~ I having the composition indicated above in Example 10. ~ .:
, For cement A, the total amount.of fluorinated - . -:oomponents depo3ited on test pieces 2, 3 and 4 was 36, 45 and 1. --60~;~9/m2 respec~ively. For cement B, the total amount of .;~
flaorinated components deposited on test piece 2 was 43 g/m2. `.
: The treatment e~ficiency was evaluated according to ., .
11 .. -'.. ~
: , the procedures described above in Example 9. The results are ~...... ... : .
, . ~, . . ~.
shown below~

. ~ 31 - :. .
~1 ~
11 , ......

1 32~1 6 . ~ .

... . ~
Test piece Absorbed wa~er amount Percent protective : :
(g/cm ) efficiency - -.

Cement A ~:
1 0.32-0.38 - ~ -2 0.154 57.0~ :~
3 0.140 60.0 4 0.047 87.0 Cement B :
1 0.36-0.44 2 O.ll~i 70.0% ~ :

`''''~ '., ' ,-"
. -': ' -. ;,, ..

::: il ~ '`

i , `:.. ..
- 32 - . .:
~: 'i, '~. '' '''' ' ,' ...~
~ ' .:

Claims (12)

1. A process for protecting marble, stone, tiles, cement, gypsum, or wood and other analogous materials utilized in particular in the building industry from the deteriorating action of atmospheric agents and pollutants, by applying onto said materials a protective agent comprising a microemulsion of perfluoropolyethers containing functionalized groups, and optionally peroxide bridges in the chain.

2. A process for protecting marble, stone, tiles, cement, gypsum, or wood and other similar materials utilized in particular in the building industry from the deteriorating action caused by atmospheric agents and pollutants, by apply-ing onto said materials a protective agent selected from products having a perfluoropolyether structure, consisting of sequences of fluoro-oxyalkylene units selected from the class consisting of:
; (CF2CF2O); ; (CF2CF2CF2O);
and (CF2CF2CH2O), and at least one functional end group, optionally also in the chain, said functional groups being represented by the formula:

CFX-(B)J-ZK

where X is F or CF3 and where J = 0 or 1, B is a divalent or polyvalent linking hydrocarbon radical, in particular an alkylene or a cycloalkylene or an arylene radical, having up to 20 carbon atoms, K varies from 1 to 3 and Z is a group capable of forming a chemical and/or physical bond with the above material and selected from:
-- a non-aromatic, non-fluorinated organic radical containing heteroatoms, which are electron doublet donors, or an aromatic radical, whether or not containing heteroatoms, capable of giving rise to coordinate bonds or to charge transfer bonds, thus causing various kinds of adsorption phenomena on the substrate;
-- -CONR2R3, -COOR, where R is H or an alkyl group containing from 1 to 8 carbon atoms, an aromatic or an alkyl-aromatic group such as benzyl;
-- -OH, -COF;
-- -NCO, -NHR, -COR; -CO-CF3; -C(OH)2-CF3;
-- SO3H;
-- polyoxyalkylene-OH; and -- quaternary ammonium;
and characterized furthermore in that the perfluoropolyether product is applied in the form of an aqueous microemulsion.

3. The process of claim 2, wherein the perfluoropolyethers utilized for preparing the microemulsion are obtained by photo-oxidation of C2F4 and/or C3F6.

4. The process of claim 3, wherein the perfluoropolyethers utilized for preparing the microemulsion are obtained through an oxidation process in the liquid phase with molecular oxygen in the presence of ultraviolet rays, of a mixture of C2F4 and/or C3F6 and a perfluorinated conjugated diene at a temperature ranging from -80° to 50°C, and subsequent heat treatment.

5. The process of claim 4, wherein the perfluoropolyethers utilized for preparing the microemulsions have one of the following formulas:
or where m, n and p are integers different from zero, and Rf and R'f may be COF groups or perfluoroalkyl groups having from 1 to 3 carbon atoms.

6. The process of claim 2, wherein the perfluorooxyalkylene units belong to one of the following classes:
(1) with a random distribution of the perfluorooxyalkylene units, where m, n, p and z have such mean values as to meet the abovesaid requirements concerning the mean molecular weight; and z is zero or an integer where Rf and R'f, either alike or different from each other, may be perfluoroalkyl end groups optionally containing 1 to 3 carbon atoms and at least one of said end groups is a functional groups of type CFX(B)J-ZK, where B, J, Z , X and K are the same as defined hereinbefore;

(2) RfO(CF2CF2O)n(CF2O)mOzR'f with a random distribution of the perfluorooxyalkylene units, where m, n and z have such values as to meet the above requirements; where Rf and R'f may be perfluoroalkylene end groups having 1 to 3 carbon atoms and at least one of said end groups is a functional group of the type (B)J, ZK, and where B, J, Z, K are the same as defined above;

(3) where m, n, p, o and z have such mean values as to meet the abovesaid requirements and Rf and R'f are the same as defined hereinbefore;

(4) where n has such an average value as to meet the abovesaid requirements, and Rf and R'f are the same as defined hereinbefore;

(5) RfO(CF2CF2O)nR'f, where n has such an average value as to meet the abovesaid requirements, and Rf and R'f are the same as defined hereinbefore;

(6) RfO(CF2CF2CF2O)nR'f or RfO(CH2CF2CF2O)nR'f, where n has such an average value as to meet the abovesaid requirements and Rf and R'f are the same as defined hereinbefore.

7. The process of claim 2, wherein the functional perfluoropolyethers have a molecular weight ranging from 1,000 to 10,000.

8. The process of claim 2, wherein the functional perfluoropolyethers have a molecular weight ranging from 2,000 to 6,000.

9. The process of claim 2, wherein said microemulsions are of the oil-in-water type or of the water-in-oil type.

10. The process of claim 2, wherein K is equal to 1 and B has up to 8 carbon atoms.

11. The process of claim 2, wherein Z is selected from COOH, OH, polyoxyalkylene-OH, and quaternary ammonium groups, -CO-CF3 and -C(OH)2)-CF3.

12. The process of claim 11, wherein the acid end group is salified.