TECHNICAL FIELD
[0001] The present invention relates to an article to which pollutants
do not easily adhere and which has excellent removal performance of
adhering pollutants and to which dust and the like do not easily adhere,
and relates to a method for producing the same.
BACKGROUND OF THE INVENTION
[0002] Substrates such as metals, glass, plastics, potteries and the
like are used as general-purpose substrates for automotive parts,
household items, home electric appliances and OA apparatus. The
surfaces of these substrates are liable to get stained by the adhesion of
waterdrops and water stain due to rain and the like, suspending dust
particles, oily matters such as tar of cigarette, fingerprints and sebum of
the human hand and the like, and therefore required to have such
antifouling functions as to be resistant to these stains and easily remove
stains that have once adhered thereto.
[0003] In order to exhibit these antifouling functions, a variety of
methods have hitherto been proposed. In Patent Publication 1, there is
disclosed an antifouling agent composition consisting of a compound
having a perfluoroalkylether group. In Patent Publication 2, there is
disclosed a glass subjected to a water repellencyimparting treatment
and excellent in water repellency, antifouling property and durability,
where a treatment film that contains as the primary component an
alkoxysilane compound having a perfluoropolyether group is formed on a
surface of a substrate. Patent Publication 3 sets forth: a fluorine-
containing polymer having a good antifouling property against oily
pollutants and particularly having a good antifouling property against
fingerprints; and an antifouling substrate on which surface a layer of the

polymer is formed. In Patent Publication 4, there are disclosed a silane
denatured with a perfluoropolyether group having an excellent in
durability, antifouling property imparting effect and particularly having
an excellent fingerprint-removability imparting effect and a surface
treatment agent containing the same as the primary component.
REFERENCES ABOUT PRIOR ART
Patent Publication
[0004] Patent Publication l: Japanese Patent Application Publication
No. 2000-234071
Patent Publication 2: Japanese Patent Application Publication
No. 11-092177
Patent Publication 3: International Application Publication No.
WO/1998/049218
Patent Publication 4: Japanese Patent Application Publication
No. 2003-238577
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] As have been discussed in the above patent publications, in
most of the cases of forming a layer that exhibits the antifouling
functions (the layer will hereinafter be referred to as an antifouling
layer) on the surface of the substrate, a fluorine-containing compound
that is high in water and oil repellency is used as a material constituting
the antifouling layer and the antifouling layer is provided with about 0.1
nm to 100 µm thickness.
[0006] In fact, when a cured condensed coating film such as the silane
denatured with a perfluoropolyether group as discussed in Patent

Publication 4 is used as an antifouling layer, an antifouling property is
excellently exhibited. However, it is difficult to say that these techniques
can sufficiently prevent the adhesion of fine contaminants such as dust
and dirt (hereinafter referred to merely as "fine substances") and
sufficiently remove adhering fine substances, and additionally, an
antifouling property and a dirt removal performance against oily
pollutants (i.e., stains due to sebum such as fingerprints, edible oil and
cosmetics) are sometimes lowered when the fine substances heavily
adhere to the coating film (see the undermentioned Comparative
Examples). For example, mirrors, displays and exterior and interior
windows may be brought into contact with a great deal of fine substances
in a short time according to environments where antifouling articles are
used (i.e., an environment where the surface is always exposed to the
outside), and the presence of the fine substances have raised a serious
problem of reduction of antifouling property.
[0007] An object of the present invention is to provide: an antifouling
article to which fine substances do not easily adhere and which has
excellent' removal performance of adhering fine substances while
exhibiting good antifouling properties and dirt removal properties even
in the cases when fine substances have adhered thereto; and a method
for producing the antifouling article.
Means for Solving the Problems
[0008] The present inventors have eagerly made studies and resulted
in a finding that the above problems can be solved by providing a
specified range of fluorine amount (fluorine concentration) per unit area
to the cured condensed coating film formed on the surface of the
substrate and an excellent antifouling property is obtained thereby.

[0009] More specifically, the present invention is an antifouling article
characterized by having a cured condensed coating film of a
perfluoropolyether group-containing silane represented by general
formula [1] on the surface of a substrate and by having a fluorine
concentration of the cured condensed coating film of 0.2-2.0 µg/cm2.

[In the formula, "W" represents a fluorine atom or a
substituent represented by the following structural formula:

"X" represents a group represented by a formula
-(0)g-(CF2)h-(CH2)i-(OC2F4)j- (in this formula, "g", "h", "i" and "j"
mutually independently represent an integer of 0 to 50, the total of "g"
and "h" is not smaller than 1, and the order of the positions of the
parenthesized repeating units is arbitrary), "Y" represents a hydrogen
atom or a C1-C5 lower alkyl group, "Z" represents at least one
hydrolyzable functional group selected from the group consisting of
alkoxyl groups such as methoxy group, ethoxy group, propoxy group,
isopropoxy group, butoxy group and the like, chloro group, amino group
and isocyanate group, "R" represents a C1-C10 alkyl group, and "V"
represents an oxygen atom or a divalent organic group, "a" is an integer
of 0 to 50, "b" is an integer of 1 to 200, "c" is an integer of 1 to 3, "d" is an
integer of 1 to 10, "e" is an integer of 0 to 4, V " is an integer of 0 or 1, "f'
is an integer of 0 to 5, "k" is an integer of 0 to 5, "1" is an integer of 0 or 1,

"m" and "n" mutually independently represent an integer of 0 to 50, and
the total of "m" and "n" is not smaller than 1.]
[0011] Furthermore, the present invention is a method for producing
the above-mentioned antifouling article, characterized by including:
(1) a step which includes an application (A) where a
perfluoropolyether group-containing silane represented by general
formula [1] is diluted with a solvent to obtain a coating agent, the coating
agent is retained in a member and then the member is brought into
contact with a surface of a substrate and reciprocated on the surface of
the substrate in an arbitrary one direction to apply the coating agent to
the whole surface and a subsequent application (B) where the member is
brought into contact with the surface of the substrate again and
reciprocated on the surface of the substrate in one direction different
from the application direction of the application (A) to stabilize the
coating agent on the whole surface; and
(2) a step of drying the applied coating agent.
EFFECTS OF THE INVENTION
[0012] The antifouling article according to the present invention has
good antifouling properties and dirt removal properties, and exhibits the
good antifouling properties even in an interior or exterior environment
ordinarily including a great deal of fine substances such as dust and dirt.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0013] Fig. 1 is a schematic view showing one example of preferable
methods of applying a coating film for forming an antifouling layer of the
present invention.

MODE(S) FOR CARRYING OUT THE INVENTION
[0014] The present invention is an antifouling article characterized by
having a cured condensed coating film of a perfluoropolyether group-
containing silane represented by general formula [1] on the surface of a
substrate and by having a fluorine concentration of the cured condensed
coating film of 0.2-2.0 µg/cm2.
[0015]

[0016] First of all, a substrate for an antifouling article of the present
invention will be discussed. The substrate of the present invention is not
particularly limited; for example, it is possible to employ a float sheet
glass used for architectural windows or a transparent inorganic sheet
glass such as soda-lime glass produced by roll forming method.
[0017] By using these sheet glasses, it is possible to form glass
windows such as display, touchscreen and showcase, glass materials for a
front glass of a game machine (i.e., a Pachinko game stand), reflecting
substrates such as a mirror, and translucent or opaque glass substrates
such as ground glass and pattern-inscribed glass.
[0018] As a substrate for the present invention other than the above-
mentioned glass substrates, it is also possible to employ substrates
formed of ceramic material used for tiles, roofing tiles, sanitary potteries,
eating utensils and the like, frame members for glass window,
cookwares, medical instruments such as scalpels and needles, stainless
steel used for sink, automotive bodies and the like, metal materials such

as aluminum and steel, plastic substrates such as polycarbonate resin,
polyethylene terephthalate resin, polymethyl methacrylate resin,
polyethylene resin and polyvinyl chloride resin and other plastic
substrates.
[0019] It is possible to use various shapes of substrates, such as flat
plate and curved plate. The size and the thickness are not particularly
limited. The cured condensed coating film that the substrate has on its
surface may be formed entirely or partially on the surface.
[0020] Then, a perfluoropolyether group-containing silane represented
by general formula [1] will be discussed.

[In the formula, "W" represents a fluorine atom or a
substituent represented by the following structural formula:

"X" represents a group represented by a formula
-(O)g-(CF2)h-(CH2)i-(OC2F4)j- (in this formula, "g", "h", "i" and "f
mutually independently represent an integer of 0 to 50, the total of "g"
and "h" is not smaller than 1, and the order of the positions of the
parenthesized repeating units is arbitrary), "Y" represents a hydrogen
atom or a C1-C5 lower alkyl group, "Z" represents at least one
hydrolyzable functional group selected from the group consisting of
alkoxyl groups such as methoxy group, ethoxy group, propoxy group,
isopropoxy group, butoxy group and the like, chloro group, amino group

and isocyanate group, "R" represents a C1-C10 alkyl group, and "V"
represents an oxygen atom or a divalent organic group, "a" is an integer
of 0 to 50, "b" is an integer of 1 to 200, "c" is an integer of 1 to 3, "d" is an
integer of 1 to 10, "e" is an integer of 0 to 4, "e' " is an integer of 0 or 1, "f"
is an integer of 0 to 5, "k" is an integer of 0 to 5, "1" is an integer of 0 or 1,
"m" and "n" mutually independently represent an integer of 0 to 50, and
the total of "m" and "n" is not smaller than 1.]
[0021] By the presence of moieties represented by -[CF2]a-,
-[CmF2mOCnF2n]b- [-(O)g-(CF2)h-(CH2)i-], -[CH2]e-, -[CH2]f- -(OC2F4)j-
and -[CH2]k- in general formula [1], it becomes possible to impart good
antifouling performance and wear resistance to the obtained cured
condensed coating film. Accordingly, a cured condensed coating film
formed by condensing the above-mentioned perfluoropolyether group-
containing silane excellently gains both antifouling performance and
wear resistance and therefore preferable.
[0022] In the general formula [1], when the repeating structure is a
perfluoroalkyl group having a carbon number of not smaller than 2, it
can take either a straight-chained or branched structure. For example, a
structure of-[CmF2mOCnF2n]b- may take a branched structure of
-[OCF(CF3)]b- if "m" is 0 and "n" is 2.
[0023] "V" in the general formula [1] represents an oxygen atom or a
divalent organic group. As an organic group, it is possible to cite amide,
N-methylamide, N-ethylamide, ester and ether, for example. Of these,
oxygen atom and amide are preferable.
[0024] A cured condensed coating film that the antifouling article of
the present invention has at the surface of a substrate is produced on the
surface of the substrate in such a manner that a bond (for example,

metalloxane bond represented by siloxane bond and the like) or an
interaction (for example, Van der Waals force, a static interaction and
the like) is caused between a functional group of a perfluoropolyether
group-containing silane represented by the general formula [1] or a
silanol group obtained such that the hydrolyzable functional group is
hydrolyzed and an active species of the surface of the substrate. The
adhesiveness between the coating film and the surface of the substrate
differs according to substrates to be used and reactivity of the functional
group, so that it is preferable to properly make examinations.
[0025] Additionally, when the reactivity of a hydrolyzable functional
group represented by "Z" in the general formula [1] is too high, not only
the coating agent becomes difficult to handle at the time of being
prepared but also the pot life of the coating agent becomes shortened
(specifically discussed below). On the contrary, an excessively low
reactivity cannot sufficiently develop the hydrolysis reaction so that the
amount of the formed silanol group becomes insufficient. With this, the
bond or interaction caused between the silanol group and the active
species of the surface of the substrate is not enough and therefore an
adequate adhesiveness may not be imparted between the coating film
and the surface of the substrate and the durability of the coating film
may sometimes be reduced. In view of the above, the hydrolyzable
functional group represented by "Z" is preferably at least one selected
from the group consisting of alkoxyl groups such as methoxy group,
ethoxy group, propoxy group, isopropoxy group, butoxy group and the
like, chloro group and isocyanate group. Of these, the hydrolyzable
functional group is preferably an alkoxyl group and more particularly
methoxy group or ethoxy group, with consideration given to ease of

handling the hydrolyzable functional group, the pot life of the coating
agent and the durability of the obtained cured condensed coating film.
[0026] A perfluoropolyether group-containing silane represented by
the general formula [1] is considered to establish a Si-O- bond between
it and the surface of the substrate through hydrolysis of a functional
group represented by "Z" of a Si-Z moiety. The number of moles of
fluorine in the perfluoropolyether group-containing silane of around 20 to
200 relative to 1 mol of silicon contained in a bondable moiety (a Si
group-containing moiety) in the perfluoropolyether group-containing
silane is preferable because an excellent water repellent performance can
be imparted to the substrate.
[0027] Of perfluoropolyether group-containing silanes represented by
the general formula [1], a perfluoropolyether group-containing silane
having a structure represented by the following general formula [2],
general formula [3] or general formula [4] is a preferable compound.

[In the formula, "Rf" represents a C1-C100 straight-chained
perfluoroalkyl group, "p" represents an integer of 1 to 100 and "q"
represents an integer of 0 to 2. "Y", "R" and "d" are the same as in the
general formula [1].]

[In the formula, "Rf2" represents a divalent group including an
unit represented by a formula -(CtF2tO)- (where "t" is an integer of 1 to
6) and having a straight-chained perfluoroalkyleneether structure with

no branch or represents a perfluoroalkyl structure including an unit
represented by -CuF2u- (where "u" is an integer of 1 to 8). Each of "r"
and V " represents an integer of 1 to 5. Each of "s" and "s' " represents
an integer of 0 to 2. "R", "Z" and "c" are the same as in the general
formula [1].]

[In the formula, "V" represents an integer of 0 to 3 and each of
"w", "x", "y" and "z" represents an integer of 0 to 50. "R", "V", "Z", "c", "k",
"1" and "e" are the same as in the general formula [1].]
As commercially available products containing the above
compounds, it is possible to cite: OPTOOL DSX and OPTOOL AES series
such as OPTOOL AES4 available from DAIKIN INDUSTRIES,LTD;
KY130 and KY108 available from Shin-Etsu Chemical Co., Ltd.; Fluoro
Surf FG-5020 available from Fluoro Technology; Dow 2634 Coating
available from Dow Corning Toray Co.,Ltd.; and the like. In the case of
preparing the coating agent of the present invention by using the above-
mentioned commercially available products, a solvent contained in the
commercially available products serves as a part of a solvent to be used
for preparing the coating agent of the present invention.
[0028] The antifouling article of the present invention is characterized
by the amount of fluorine per unit area (the "amount of fluorine" will
hereinafter be referred to as merely "a fluorine concentration"). The
fluorine concentration in the present invention is obtained by the
following method.

[0029] (1) By using a X-ray fluorescence analyzer ZSX PrimusII
(manufactured by Rigaku Corporation), a calibration curve was
calculated from the standard sample of known concentration. (2)
Calibration curves of two arbitrary points of cured condensed coating
film sample were measured thereby each fluorine concentration of them
was calculated. (3) The average value of the two calculated value was
defined as the fluorine concentration of the antifouling article.
[0030] It is important for the antifouling article of the present
invention that the fluorine concentration is 0.2 to 2.0 µg/cm2. If the
fluorine concentration is lower than 0.2 µg/cm2, a sufficient antifouling
property cannot be obtained. On the contrary, if the fluorine
concentration is larger than 2.0 µg/cm2, the fine substances easily adhere
to the surface and removal performance of adhering fine substances is
reduced. The antifouling article preferably has a fluorine concentration
of 0.3 to 1.8 µg/cm2, particularly preferably 0.4 to 1.7 µg/cm2. If
variations in fluorine concentration of arbitrary portions of the
antifouling article become smaller, unevenness of the antifouling effect
becomes more dissolved; therefore this is preferable since the appearance
is not impaired.
[0031] Furthermore, the present invention is a method for producing
the antifouling article, characterized by including:
(1) a step which includes an application (A) where a
perfluoropolyether group-containing silane represented by general
formula [1] is diluted with a solvent to obtain a coating agent, the coating
agent is retained in a member and then the member is brought into
contact with a surface of a substrate and reciprocated on the surface of
the substrate in an arbitrary one direction to apply the coating agent to

the whole surface and a subsequent application (B) where the member is
brought into contact with the surface of the substrate again and
reciprocated on the surface of the substrate in one direction different
from the application direction of the application (A) to stabilize the
coating agent on the whole surface,' and
(2) a step of drying the applied coating agent.
This production method will be discussed below.
[0032] A coating agent used for producing the antifouling article (the
agent may hereinafter be referred to as "a cured condensed coating film-
forming coating agent", "a coating film-forming coating agent" or merely
"a coating agent") will now be discussed. The coating agent is required
only to be one that contains a perfluoropolyether group-containing silane
represented by general formula [1] and one that can be evenly applied to
a surface of a substrate. However, for ease of application, it is usually
preferable to use one diluted with an organic solvent which can dissolve
the perfluoropolyether group-containing silane therein. The organic
solvent preferably contains 60 to 100 mass% of a fluorine-based solvent.
A concentration of the fluorine-based solvent in the organic solvent of
lower than 60 mass% is not preferable because the perfluoropolyether
group-containing silane cannot sufficiently be dissolved or a coating
unevenness occurs. Moreover, in the case where application is
continuously conducted in the open system on a great many substrates,
the cured condensed coating film becomes easily affected by
concentration variations of the perfluoropolyether group-containing
silane contained in the coating agent with evaporation of the organic
solvent and therefore the appearance and the antifouling property of the
cured condensed coating film tend not to be stabilized according to

substrates. The fluorine-based solvent contained in the organic solvent
preferably has a concentration of 70 to 100 mass%, more preferably 80 to
100 mass%.
[0033] The organic solvent contained in the coating agent preferably
has a surface tension of not higher than 20.0 mN/m. If the organic
solvent is one having a surface tension of higher than 20.0 mN/m, a
condition where a puddle portion and the other portion are mixed tends
to occur at the time of applying the coating agent to a substrate, because
of an aggregating action of the coating agent. It is possible to obtain a
visually even cured condensed coating film by wiping the surface of the
cured condensed coating film produced after drying so as to remove an
excess coating agent,' however, when the surface of the cured condensed
coating film is exposed to a steam such as water vapor, a portion that
had been the puddle portion at one time is selectively subjected to the
adhesion of liquid drops and therefore whitish dots easily appear on the
surface of the cured condensed coating film, which is not preferable. The
more preferable solvent is a solvent having a surface tension of not
higher than 19.5 mN/m and more preferably a solvent having a surface
tension of not higher than 19.3 mN/m. Incidentally, the surface tension
of liquid can be measured by Wilhelmy plate method, for example.
[0034] Moreover, the boiling point of the organic solvent is not
particularly limited but usually preferably 50 to 250°C from the
viewpoint of ease of operation. An organic solvent having a boiling point
of lower than 50°C is too high in a velocity at which the applied coating
liquid reaches dryness so as to tend to cause a coating unevenness.
Additionally, the organic solvent contained in the coating agent may be
volatilized at some midpoint of application, so that the coating agent
cannot be completely spread over the surface of the substrate.

Furthermore, in the case where application is continuously conducted in
the open system on a great many substrates, the concentration of the
perfluoropolyether group-containing silane in the coating agent becomes
higher with evaporation of the organic solvent, so that the appearance
and the antifouling property of the cured condensed coating film tend not
to be stabilized according to substrates. An organic solvent having a
boiling point exceeding 250°C requires a higher temperature or a longer
period of time for drying the coating agent, which tends to increase
disadvantages in terms of cost. The boiling point of the organic solvent is
preferably 60 to 220°C, particularly preferably 70 to 200°C.
[0035] The fluorine-based solvent is preferably at least one kind
selected from the group consisting of hydrofluorocarbons,
perluorocarbons, perfluoroethers, hydrofluoroethers and
hydrochlorofluorocarbons. Considering an adequate surface tension and
an adequate boiling point, more preferable examples are
perfluorocarbons and hydrofluoroethers. In view of environmental
burden, the fluorine-based solvent is particularly preferably a
hydrofluoroether having a smaller global warming potential.
[0036] A preferable example in the case of using of the organic solvent
as one kind of organic solvent is as follows. For example, it is possible to
use a perfluorocarbon such as perfluorononane, perfluorodecane, a
fluorine-based inert liquid (e.g. "Fluorinert FC40", "Fluorinert FC43" and
"Fluorinert FC3283" available from Sumitomo 3M Limited) and the like,
and a hydrofluoroether such as 1,1,1,2,3,3-hexafluoro-4-(1, 1,2,3,3,3-
hexafluoropropoxy)-pentane ("Novec 7600" available from Sumitomo 3M
Limited) and the like. It is also possible to use two or more kinds of
organic solvents as the above-mentioned organic solvent, in which the
surface tension of the organic solvent after mixing is preferably not

larger than 20.0 mN/m and the boiling point of the same is preferably 50
to 200°C. A mixture liquid of the above-mentioned fluorine-based solvent
may be employed. Additionally, it is possible to use a mixture liquid
obtained by mixing: hydrofluorocarbons such as 1,1,2,2,3,3,4,4
octafluorobutane, l,3-bis(trifluoromethyl)benzene,
heptafluorocyclopentane ("ZEORORA-H" available from ZEON
CORPORATION), 2H,3H-decafluoropentane ("Vertrel XF" available from
Mitsui DuPont Fluorochemical), 1,1,1,3,3,3-hexafluoroisopropanol and
the like; perluorocarbons including perfluoroalkanes represented by
CnF2n+2, such as perfluorohexane, perfluoroheptane and perfluorooctane
("Fluorinert PF5060", "Fluorinert PF5070" and "Fluorinert PF5080",
respectively, available from Sumitomo 3M Limited), hexafluorobenzene,
perfluoro-l,3-dimethylcyclohexane, a fluorine-based inert liquid (such as
"Fluorinert FC" series) and the like; perfluoroethers such as perfluoro(2-
butyltetrahydrofuran) and the like; hydrofluoroethers such as
methylperfluorobutylether ("Novec 7100" available from Sumitomo 3M
Limited), nonafluorobutylethylether ("Novec 7200" available from
Sumitomo 3M Limited), methylperfluorohexylether ("Novec 7300"
available from Sumitomo 3M Limited) and the like;
hydrochlorofluorocarbons such as l,2-dichloro-3,3,3-trifuoropropene, 1-
chloro-3,3,3-trifluoropropene, 3,3-dichloro-l,l,l,2,2-pentafluoropropane
("HCFC-225" available from ASAHI GLASS CO., LTD.) and the like; and
hydrocarbon-based solvents such as butane, hexane, 2-methylpentane,
2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylhexane and the like
with the avobe-mentioned fluorine "based solvent and a mixture liquid
thereof.
[0037] The concentration of the perfluoropolyether group-containing
silane in the coating agent is preferably 0.01 to 5 mass%. A

concentration of less than 0.01 mass% is not preferable because the
antifouling property on the surface of the substrate may not sufficiently
be exhibited and the cured condensed coating film is formed unevenly. A
concentration of more than 5 mass% is also not preferable because an
excess portion of the cured condensed coating film becomes difficult to be
removed and the amount of the excess portion becomes so increased as to
result in an additional cost. Furthermore, such concentrations make the
adhesion of the fine substances easily occur and reduce the removal
performance of adhering fine substances, and therefore not preferable.
From the viewpoint of the antifouling property, an ability to remove the
excess portion and cost, a more preferable concentration range is 0.05 to
1 mass% and a much more preferable concentration range is 0.1 to 0.4
mass%.
[0038] Additionally, the cured condensed coating film-forming coating
agent may contain a compound formed in such a manner that a
hydrolyzable functional group of a perfluoropolyether group-containing
silane represented by the generalformula [1] causes a partial hydrolysis
or condensation reaction in a molecule or between molecules, in addition
to the perfluoropolyether group-containing silane.
[0039] Additionally, the cured condensed coating film-forming coating
agent may contain a catalyst for the purpose of accelerating the
hydrolysis or condensation reaction of the perfluoropolyether group-
containing silane represented by the general formula [1]. The catalyst is
exemplified by organic tin compounds such as dibutyltin methoxide and
dibutyltindilaurate, organic titanium compounds such as tetra-n-butyl
titanate, organic acids such as acetic acid, methanesulfonic acid and
trifluoroacetic acid, inorganic acids such as hydrochloric acid and sulfuric
acid and the like. In particular, acetic acid, tetra-n-butyl titanate,

dibutyltindilaurate and the like are preferable. The adding amount is
preferably a usual catalyst amount.
[0040] Additionally, to the cured condensed coating film-forming
coating agent, there may be added a surfactant, a cross-linking agent, an
antioxidant, a UV absorber, an IR absorber, a flame retardant, a
hydrolysis inhibitor, an antifungal agent or the like within a range not to
affect the scope of the present invention.
[0041] In order to further improve the durability of the antifouling
article, it is also possible to previously conduct a treatment on the
surface of the substrate, the treatment for improving the adhesive
strength between the substrate and the cured condensed coating film.
The treatment is exemplified by treatments for generating active groups
on the surface of the substrate, such as polishing, rinsing and drying
with the use of various polishing liquids, a surface reforming treatment
using an acid or basic solution, a primer treatment, plasma radiation,
corona discharge, high-pressure mercury lamp irradiation and the like.
The active species and a hydrolyzable functional group represented by
"Z" in the general formula [1] or a silanol group obtained such that the
hydrolyzable functional group is hydrolyzed cause a bond (for example,
metalloxane bond represented by siloxane bond and the like) or
interaction (for example, Van der Waals force, a static interaction and
the like) therebetween, thereby allowing imparting a sufficient
adhesiveness between the cured condensed coating film and the surface
of the substrate.
[0042] As a method for applying the cured condensed coating film-
forming coating agent to the surface of the substrate, it is possible to
employ various application methods such as brush application, human

hand coating, robot application and any combination of these.
Incidentally, application can be performed by fixing a member for
retaining the coating agent so as to bring the member into contact with
the surface of the substrate and then by moving the substrate. Brush
application, hand coating and robot application are preferable because
these methods do not so limit the form or size of the substrate to be
subjected to application and therefore various kinds of substrates are
usable. In particular, hand coating is more preferable.
[0043] The member for retaining the coating agent is exemplified by
nonwoven fabrics of which raw material is pulp, acrylic fiber, PET, PP,
nylon, rayon or the like. In particular, a composite material of PP and
pulp is preferable from the viewpoint of strength and absorbency.
[0044] Then, there will hereinafter be discussed steps (1) and (2),
characteristics of the production method of the present invention.
[0045] In a first step (1) for applying the coating agent to a surface of a
substrate, an application (A) is conducted thereby spreading the coating
agent all over the surface of the substrate. Then an application (B) is
conducted thereby leveling the surface of a coating layer evenly. A
reciprocating direction of the member in the application (B) is not
particularly limited, but preferably one that forms an angle 0 between
the reciprocating direction of the member in the application (A) and the
reciprocating direction of the member in the application (B) of 20 to 160°
since the coating agent can be more evenly applied. A more preferable
direction is one that forms an angle of 45 to 135°. An article obtained by
such an application method exhibit a preferable range of fluorine
concentration. Furthermore, by performing an application (C), it
becomes possible to reliably apply the coating agent to an edge portion

that tends to undergo a lack of application or a shortage of the coating
agent.
[0046] A step (2) to be performed after applying the coating agent to
the substrate is a step for drying the coating agent, and concurrently it
serves as a step for accelerating condensation of the perfluoropolyether
group-containing silane so as to form a cured condensed coating film
while causing a bond or interaction between a silanol group formed from
the perfluoropolyether group-containing silane and an active species of
the surface of the substrate to impart a sufficient adhesiveness between
the cured condensed coating film and the surface of the substrate. This
drying step is preferably conducted at 50 to 250°C, more preferably 100
to 200°C, and it may be performed under any of atmospheric pressure,
applied pressure and reduced pressure or in an inert atmosphere.
Additionally, heating with microwave is effective too.
[0047] In the case where the cured condensed coating film obtained
after the drying step has an excess portion on its surface, the excess
portion is wiped and removed. When being wiped with a paper towel or
cloth moistened with an organic solvent and/or a dried paper towel or
cloth, the cured condensed coating film is obtained to have an even
surface. It is particularly preferable to wipe the excess portion with
disposable papers such as paper towel and tissue paper.
EXAMPLES
[0048] Hereinafter the present invention will specifically be explained
with reference to examples; however, the present invention is not limited
by these examples.
[0049] In Examples and Comparative Examples, an antifouling layer-
forming coating agent was prepared and then applied onto a substrate

thereby producing an antifouling article. A method for preparing a
coating agent and a method for producing the antifouling article are as
discussed below. Additionally, by applying the following methods, there
were conducted quality evaluations in terms of surface tension of an
organic solvent used for the coating agent and an antifouling layer of the
obtained antifouling article.
[0050] [Dust Adhesion]
Bemcot M-1 (a wiper for an industrial use, available from Asahi
Kasei Corporation) to which dust adhered in an amount of 20 mg was
brought into contact with 100 cm2 of a surface of a sample (100 cm2) and
then the appearance of the surface of the sample was visually inspected
thereby evaluating the sample by the following criteria.
A: Area of surface of sample covered with dust is smaller than 5 %
B: Area of surface of sample covered with dust is 5 to 20 %
C: Area of surface of sample covered with dust is larger than 20 %
[0051] [Dust Removal Performance]
Dust in an amount of 10 mg was adhered to 100 cm2 of a surface of
a sample and then wiped with Bemcot M-l. The number of wipes was
measured until the dust was completely removed.
A: 1 wipe
B: 2 wipes
C: 3 or more wipes
[0052] [Oi] Removal Performance under Condition of Dust Adhering]
Dust in an amount of 10 mg was adhered to 100 cm2 of a
surface of a sample and 30 mg of oil (a salad oil available from The

Nisshin OilliO Group, Ltd.) was dropped thereon, followed by wiping it
with Bemcot M-l. The number of wipes was measured until the dust
was completely removed.
A: 10 or less wipes
B: 10-40 wipes
C: 40 or more wipes
[0053] [Fluorine Concentration]
The fluorine concentration was measured by using a X-ray
fluorescence analyzer ZSX PrimusII (manufactured by Rigaku
Corporation). The fluorine concentration was obtained by the following
method.
(1) By using a X-ray fluorescence analyzer ZSX PrimusII
(manufactured by Rigaku Corporation), a calibration curve was
calculated from the standard sample of known concentration. (2)
Calibration curves of two arbitrary points of the sample were measured
thereby each fluorine concentration of them was calculated. (3) The
average value of the two calculated value was defined as the fluorine
concentration of the antifouling article.
[0054] [Example 1]
(I) Preparation of Cured Condensed Coating Film-Forming
Coating Agent
In 50.0 gof Novec 7600 (l, 1,1,2,3,3-hexafluoro-4-(l, 1,2,3,3,3-
hexafluoropropoxy)pentane available from Sumitomo 3M Limited)
having a surface tension of 17.7 mN/m and a boiling point of 131°C, 0.75
g of OPTOOL DSX (available from DAIKIN INDUSTRIES,LTD) (a
perfluorohexane solution of a perfluoropolyether group-containing silane,

having a solid content of 20 mass% and having a probable structure of
general formula [2]) was dissolved, followed by stirring for 30 minutes at
room temperature, thereby obtaining a coating agent having a
concentration of the perfluoropolyether group-containing silane of 0.3
mass%.
[0055] (II) Preparation of Substrate (Glass Substrate)
A surface of a float glass substrate having a size of
200mm*200mm*2mm thickness was polished by using a polishing liquid
and then rinsed with water and dried. Incidentally, a 2 mass% ceria
slurry obtained by mixing a glass polishing agent MIREK A (T)
(available from MITSUI MINING & SMELTING CO..LTD.) with water
was used as the polishing liquid.
[0056] (III) Formation of Cured Condensed Coating Film
As an application (A), a cotton cloth (a trade name of Bemcot
M-1) impregnated with 4.0 ml of the coating agent that had been
prepared according to the above section (I) was brought into contact with
the glass substrate and then reciprocated in an arbitrary one direction as
shown in Fig. 1 (i.e., the lateral direction of Fig. 1) so as to apply the
coating agent to the whole surface. As a subsequent application (B), the
cloth was reciprocated in a direction that forms an angle of about 90° to
the application direction of the application (A) (i.e., the vertical direction
of Fig. 1) so as to apply the coating agent to the whole surface. As a final
application (C), the coating agent was applied along an edge portion of
the substrate (indicated in Table 1 by "preferable hand coating (90°)"),
followed by bringing the glass substrate into an electric furnace to dry it
for 12 minutes. At this time, the maximum attained temperature (or
drying temperature) of the glass was 150°C. Finally, an unevenly

remaining whitish excess portion which comfirmed by visual inspection
was wiped away by using a paper towel moistened with NEOCOL CP,
thereby obtaining a sample that had a visually transparent cured
condensed coating film having an even surface. The thus obtained
antifouling article was rated "A" on the criterion for dust adhesion, "A"
on the criterion for dust removal performance and "A" on the criterion for
oil removal performance. Moreover, the fluorine concentration was 0.93
µg/cm2. The results are shown in Table 1.
[0057] [Example 2]
The procedure of Example 1 was repeated with the exception
that the reciprocation of the application (B) in Fig. 1 was conducted in a
direction forming an angle of about 60° to the application direction of the
application (A) to apply the coating agent the whole surface, thereby
obtaining a sample having a cured condensed coating film.
[0058] The thus obtained antifouling article was rated "A" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "A" on the criterion for oil removal performance.
[0059] Additionally, the fluorine concentration was 0.94 µg/cm2. The
results are shown in Table 1.
[0060] [Example 3]
The procedure of Example 1 was repeated with the exception
that the reciprocation of the application (B) in Fig. 1 was conducted in a
direction forming an angle of about 45° to the application direction of the
application (A) to apply the coating agent the whole surface, thereby
obtaining a sample having a cured condensed coating film.

[0061] The thus obtained antifouling article was rated "A" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "A" on the criterion for oil removal performance.
[0062] Additionally, the fluorine concentration was 0.90 µg/cm2. The
results are shown in Table 1.
[0063] [Example 4]
The procedure of Example 1 was repeated with the exception
that the perfluoropolyether group-containing silane had a concentration
of 0.2 wt%, thereby obtaining a sample having a cured condensed coating
film. The thus obtained antifouling article was rated "A" on the criterion
for dust adhesion, "A" on the criterion for dust removal performance and
"A" on the criterion for oil removal performance. Additionally, the
fluorine concentration was 0.85 µg/cm2. The results are shown in Table
1.
[0064] [Example 5]
The procedure of Example 1 was repeated with the exception
that the perfluoropolyether group-containing silane had a concentration
of 0.05 wt%, thereby obtaining a sample having a cured condensed
coating film. The thus obtained antifouling article was rated "A" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "A" on the criterion for oil removal performance.
Additionally, the fluorine concentration was 0.70 µg/cm2. The results are
shown in Table 1.
[0065] [Example 6]
The procedure of Example 1 was repeated with the exception
that KY130 was used as the perfluoropolyether group-containing silane,

thereby obtaining a sample. The cured condensed coating film of the
thus obtained antifouling article was rated "A" on the criterion for dust
adhesion, "A" on the criterion for dust removal performance and "A" on
the criterion for oil removal performance. Additionally, the fluorine
concentration was 1.02 µg/cm2. "KY130" is a metaxylene hexafluoride
solution of a perfluoropolyether group-containing silane, having a solid
content of 20 mass% and having a probable structure of general formula
[3]. The results are shown in Table 1.
[0066] [Example 7]
The procedure of Example 3 was repeated with the exception
that KY130 was used as the perfluoropolyether group-containing silane,
thereby obtaining a sample having a cured condensed coating film. The
thus obtained antifouling article was rated "A" on the criterion for dust
adhesion, "A" on the criterion for dust removal performance and "A" on
the criterion for oil removal performance. Additionally, the fluorine
concentration was 1.14 µg/cm2. The results are shown in Table 1.
[0067] [Example 8]
The procedure of Example 4 was repeated with the exception
that Dow 2634 Coating was used as the perfluoropolyether group-
containing silane, thereby obtaining a sample having a cured condensed
coating film. The thus obtained antifouling article was rated "A" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "A" on the criterion for oil removal performance.
Additionally, the fluorine concentration was 1.22 µg/cm2. The results are
shown in Table 1. "Dow 2634 Coating" is a mixture solution of a
perfluoropolyether group-containing silane, ethylperfluorobutylether and
ethylperfluoroisobutylether, available from Dow Corning Toray Co.,Ltd.,

having a solid content of 20 mass% and having a probable structure of
general formula [4]. The results are shown in Table 1.
[0068] [Comparative Example l]
The procedure of Example 1 was repeated with the exception
that application was achieved only by employing Mayer bar method as
an application method and then successively shifted to the drying step,
thereby obtaining a sample having a cured condensed coating film. The
thus obtained antifouling article was rated "B" on the criterion for dust
adhesion, "A" on the criterion for dust removal performance and "B" on
the criterion for oil removal performance. Additionally, the fluorine
concentration was 2.12 µg/cm2. The results are shown in Table 1.
[0069] [Comparative Example 2]
The procedure of Example 1 was repeated with the exception
that application was achieved only by employing spin coating as an
application method and then successively shifted to the drying step,
thereby obtaining a sample having a cured condensed coating film.
[0070] The thus obtained antifouling article was rated "B" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "B" on the criterion for oil removal performance.
[0071] Additionally, the fluorine concentration was 2.32 µg/cm2. The
results are shown in Table 1.
[0072] [Comparative Example 3]
The procedure of Example 1 was repeated with the exception
that application was achieved only by employing dip coating as an
application method and then successively shifted to the drying step,
thereby obtaining a sample having a cured condensed coating film. The

thus obtained antifouling article was rated "B" on the criterion for dust
adhesion, "A" on the criterion for dust removal performance and "B" on
the criterion for oil removal performance. Additionally, the fluorine
concentration was 2.21 µg/cm2. The results are shown in Table 1.
[0073] [Comparative Example 4]
The procedure of Example 1 was repeated with the exception
that application was achieved only by employing curtain flow coating as
an application method and then successively shifted to the drying step,
thereby obtaining a sample having a cured condensed coating film. The
thus obtained antifouling article was rated "B" on the criterion for dust
adhesion, "A" on the criterion for dust removal performance and "B" on
the criterion for oil removal performance. Additionally, the fluorine
concentration was 2.35 µg/cm2. The results are shown in Table 1.
[0074] [Comparative Example 5]
The procedure of Comparative Example 2 was repeated with
the exception that KY130 was used as the perfluoropolyether group-
containing silane, thereby obtaining a sample having a cured condensed
coating film. The thus obtained antifouling article was rated "B" on the
criterion for dust adhesion, "A" on the criterion for dust removal
performance and "C" on the criterion for oil removal performance.
Additionally, the fluorine concentration was 2.49 µg/cm2. The results are
shown in Table 1.

INDUSTRIAL APPLICABILITY
[0075] The antifouling article of the present invention exhibits an
excellent antifouling property in indoor environment such as living
space, kitchen, water-related space, vestibule, bathroom, toilet and the
like, outdoor environment with many dust particles and a housed
environment such as in a bag or a cloth pocket. Additionally, the
excellent antifouling property is exhibited even in an environment where
oily pollutants (i.e., stains due to sebum such as fingerprints, edible oil
and cosmetics) are sometimes lowered when the fine substances heavily
adhere to the coating film. More specifically, the excellent antifouling
property can be imparted by using the antifouling article for
architectural glass windows, doors, room partitions, tiles, table tops,
wallpapers, showcases (for goods for sale, or for doll display), displays or
touchscreen of electric or electronic equipment such as TV, cell phone,
PC, ATM and digital photo frame, covers for lighting fixture, taps,
mirrors, walls, cabinets, washbowls, counters, kitchen hoods, ventilating
fans, stoves, thermal insulating cases used in convenience stores and the
like.
EXPLANATION OF REFERENCE NUMERALS
[0076] 1 Substrate
2 Member retaining a coating agent
3 Direction in which the coating agent is applied while
bringing the member retaining the coating agent into contact with the
substrate

WE CLAIM:
1. An antifouling article characterized by having a cured
condensed coating film of a perfluoropolyether group-containing silane
represented by general formula [1] on the surface of a substrate and by
having a fluorine concentration of the cured condensed coating film of
0.2-2.0 µg/cm2.

[In the formula, "W" represents a fluorine atom or a
substituent represented by the following structural formula:

"X" represents a group represented by a formula
-(O)g-(CF2)h-(CH2)i-(OC2F4)j- (in this formula, "g", "h", "i" and "j"
mutually independently represent an integer of 0 to 50, the total of "g"
and "h" is not smaller than 1, and the order of the positions of the
parenthesized repeating units is arbitrary), "Y" represents a hydrogen
atom or a C1-C5 lower alkyl group, "Z" represents at least one
hydrolyzable functional group selected from the group consisting of
alkoxyl groups such as methoxy group, ethoxy group, propoxy group,
isopropoxy group, butoxy group and the like, chloro group, amino group
and isocyanate group, "R" represents a C1-C10 alkyl group, and "V"
represents an oxygen atom or a divalent organic group, "a" is an integer
of 0 to 50, "b" is an integer of 1 to 200, "c" is an integer of 1 to 3, "d" is an

integer of 1 to 10, "e" is an integer of 0 to 4, V " is an integer of 0 or 1, "f
is an integer of 0 to 5, "k" is an integer of 0 to 5, "1" is an integer of 0 or 1,
"m" and "n" mutually independently represent an integer of 0 to 50, and
the total of "m" and "n" is not smaller than 1.]
2. A coating agent for forming a coating film, the agent being used
for producing a cured condensed coating film formed on an antifouling
article as claimed in claim 1, characterized in that the coating agent
contains a perfluoropolyether group-containing silane represented by
general formula [1].
3. A method for producing an antifouling article as claimed in
claim 1, characterized by including:
(1) a step which includes an application (A) where a
perfluoropolyether group-containing silane represented by general
formula [1] is diluted with a solvent to obtain a coating agent, the coating
agent is retained in a member and then the member is brought into
contact with a surface of a substrate and reciprocated on the surface of
the substrate in an arbitrary one direction to apply the coating agent to
the whole surface and a subsequent application (B) where the member is
brought into contact with the surface of the substrate again and
reciprocated on the surface of the substrate in one direction different
from the application direction of the application (A) to stabilize the
coating agent on the whole surface; and
(2) a step of drying the applied coating agent.
4. A method for producing an antifouling article as claimed in
claim 1, characterized by including:
(1) a step which includes an application (A) where a
perfluoropolyether group-containing silane represented by general

formula [1] is diluted with a solvent to obtain a coating agent, the coating
agent is retained in a member and then the member is brought into
contact with a surface of a substrate and reciprocated on the surface of
the substrate in an arbitrary one direction to apply the coating agent to
the whole surface, a subsequent application (B) where the member is
brought into contact with the surface of the substrate again and
reciprocated on the surface of the substrate in one direction different
from the application direction of the application (A) to stabilize the
coating agent on the whole surface, and a final application (C) where the
coating agent is applied along an edge portion of the substrate; and
(2) a step of drying the applied coating agent.