Surface modifier

A surface modifier comprising a block copolymer obtained by polymerizing a polyfluoroalkyl group-containing compound in the presence of a chain transfer agent composed of a polysiloxane having a mercapto group at its terminal, said block copolymer containing polymer segments of said polysiloxane and polymer segments of said compound, as essential components.

The present invention relates to a surface modifier comprising, as the 
essential component, a block copolymer containing fluorine-containing 
segments and siloxane segments. 
In the surface modification of a solid, it has been known to improve the 
surface properties by using a fluorine-containing polymer or oligomer, or 
a reactive monomer. The surface properties to be improved include water 
repellency, oil repellency, stainproofing properties, lubricating 
properties, non-adhesiveness, etc. 
Among such fluorine-containing surface modifiers, an acrylic copolymer, a 
polyether copolymer and a urethane oligomer are known as a polymer or 
oligomer type modifier. However, modifiers composed mainly of such a 
polymer or oligomer are hardly capable of simultaneously satisfying 
mutually opposing properties such as flexibility and durability, solvent 
resistance and water resistance, or flexibility and stainproofing 
properties. It has been proposed to blend two or more polymers or 
oligomers to satisfy such mutually opposing properties, but there has been 
a problem in the compatibility. 
On the other hand, graft or block copolymerization of different polymers or 
oligomers is used as an important means for improving the physical 
properties of the copolymer thereby obtained. For instance, it is known to 
use a (meth)acrylate having a silicone skeleton, as a monomer, in the 
composition of an acrylate copolymer (Japanese Unexamined Patent 
Publication No. 190408/1985). This treating agent is a graft copolymer and 
is capable of imparting flexibility when applied for the treatment of 
fibers. However, it is inferior in providing durability such as dry 
cleaning resistance. On the other hand, a fluorine-containing urethane 
compound-organosiloxane composition as disclosed in U.S. Pat. No. 
4,098,742 or in Japanese Unexamined Patent Publication No. 81278/1985, is 
capable of imparting durability, but is inferior in providing flexibility. 
As a technique in which a block copolymer is used as a surface modifier 
for the treatment of fibers, a SR (soil release) treating agent is known, 
in which a polyalkyleneoxide-acrylate copolymer is used (U.S. Pat. No. 
3,278,352). However, with a block copolymer of this type, it has still 
been difficult to simultaneously satisfy the durability (washability) and 
the flexibility, although the soil release properties can thereby be 
imparted. 
As a result of extensive studies to overcome the above-mentioned drawbacks 
of the conventional treating agents, it has now been found that a block 
copolymer comprising fluorine-containing segments and siloxane segments 
exhibits excellent surface modifying effects and yet is capable of 
satisfying the above-mentioned mutually opposing properties. 
The present invention provides a novel surface modifier comprising a block 
copolymer obtained by polymerizing a polyfluoroalkyl group-containing 
compound in the presence of a chain transfer agent composed of a 
polysiloxane having a mercapto group at its terminal, said block copolymer 
containing polymer segments of said polysiloxane and polymer segments of 
said compound, as essential components. 
Now, the present invention will be described in detail with reference to 
the preferred embodiments. 
In the present invention, there is no particular restriction as to the 
polyfluoroalkyl group-containing polymerizable compound, so long as it is 
capable of being polymerized by chain transfer polymerization by a chain 
transfer agent composed of a polysiloxane. However, polyfluoroalkyl 
group-containing unsaturated esters are particularly preferred. As such 
unsaturated esters, the following acrylates or methacrylates are 
preferred. The polyfluoroalkyl group preferably has a carbon number of 
from 3 to 21, and particularly preferred is a perfluoroaalkyl group. The 
one having from 6 to 18 carbon atoms is particularly preferred, when the 
solubility in an organic solvent and the surface modifying properties are 
taken into consideration. Preferred specific examples include the 
following acrylates or methacrylates having polyfluoroalkyl groups at 
their terminals. 
##STR1## 
In order to improve the adhesive properties of the copolymer constituting 
the surface modifier of the present invention to a substrate, the 
crosslinking properties within the copolymer molecules, or the 
film-forming properties, flexibility, etc. of the copolymer, it is 
preferred to copolymerize the following copolymerizable compounds to the 
above-mentioned polyfluoroalkyl group-containing polymerizable compound. 
Namely, it is possible to copolymerize one or more polymerizable compounds 
containing no polyfluoroalkyl group, as constituting units of the 
copolymer, such as ethylene vinyl acetate, vinyl chloride, vinyl fluoride, 
vinylidene halide, styrene, .alpha.-methylstyrene, p-methylstyrene, 
acrylic acid and its alkyl ester, methacrylic acid and its alkyl ester, a 
poly(oxyalkylene) (meth)acrylate, (meth)acrylamide, diacetone 
(meth)acrylamide, methylol-modified diacetone (meth)acrylamide, N-methylol 
(meth)acrylamide, a vinyl alkyl ether, a halogenated alkyl vinyl ether, a 
vinyl alkyl ketone, butadiene, isoprene, chloroprene, glycidyl 
(meth)acrylate, 2-hydroxyethyl (meth)acrylate, aziridinylethyl 
(meth)acrylate, benzyl (meth)acrylate, isocyanatoethyl (meth)acrylate, 
cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, maleic anhydride, 
aziridinyl (meth)acrylate, a polysiloxane-containing (meth)acrylate, and 
N-vinylcarbazole. 
Such copolymerizable compounds may be copolymerized in an amount of from 0 
to 70 mol%, preferably from 1 to 50 mol%, relative to the polyfluoroalkyl 
group-containing polymerizable compound. If the amount is less than 1 
mol%, no adequate effect for the improvement of the flexibility, 
adhesiveness, film-forming properties and crosslinking properties will be 
obtained. On the other hand, if the amount exceeds 50 mol%, the surface 
modifying effects tend to deteriorate. 
In the present invention, the chain transfer agent composed of a 
polysiloxane having a mercapto group at its terminal, is represented by 
the following formula: 
##EQU1## 
wherein A is a monovalent organic group having a mercapto group at its 
terminal, 0&lt;a&lt;4, R is a substituted or unsubstituted monovalent 
hydrocarbon group having not higher than 20 carbon atoms, 0.ltoreq.b&lt;4, 
and 0&lt;a+b&lt;4. 
This polysiloxane is a silicone containing dimethylsiloxane, 
methylphenylsiloxane or an alkylmethylsiloxane as a constituting unit, and 
essentially contains mercapto groups in its molecule within the 
above-mentioned range. 
Further, it may contain a crosslinkable group, a reactive group or a 
substitutional group having a reactive group curable by a curing catalyst. 
Specific examples of such compounds will be given. Here, Me represents a 
methyl group. 
##STR2## 
In the above formulas, 1, m, n and r are integers preferably within ranges 
of 0.ltoreq.1,m,n.ltoreq.150, and 1.ltoreq.r.ltoreq.50, more preferably 
within ranges of 5.ltoreq.1,m,n.ltoreq.75, and 1.ltoreq.r.ltoreq.10. 
A includes, for example, the following organic groups: 
##STR3## 
R which may be the same or different is a substituted or unsubstituted 
monovalent hydrocarbon group having not higher than 20 carbon atoms, which 
includes an alkyl group, a cycloalkyl group and an aralkyl group. The 
substituent includes a halogen such as F, Cl or Br, an amino group, an 
epoxy group and a cyano group. In the case of a fluorine-containing 
polysiloxane wherein a part of R is, for example, --C.sub.2 H.sub.4 
R.sub.f (R.sub.f is a polyfluoroalkyl group having from 1 to 21 carbon 
atoms), the compatibility with the polyfluoroalkyl group-containing 
copolymerizable compound increases, whereby the efficiency for emulsion 
polymerization improves remarkably. 
The molar ratio of the polymer segments of the polyfluoroalkyl 
group-containing polymerizable compound to the polymer segments of the 
polysiloxane in the block copolymer of the present invention is preferably 
from 0.1 to 10, more preferably from 0.5 to 5. If the polysiloxane is 
excessive, the surface modifying effects tend to be low, or the 
copolymerization tends to hardly proceed. On the other hand, if the ratio 
of polysiloxane is too small, it becomes difficult to simultaneously 
obtain the mutually opposing properties such as the solvent resistance and 
the flexibility, etc. 
It is important to conduct chain transfer polymerization so that the molar 
amount of the polymer segments of the polyfluoroalkyl group-containing 
polymerizable compound per one mercapto group is from 2 to 100, preferably 
from 10 to 30. If the amount is too small, the effectiveness tends to be 
low. On the other hand, if the amount is excessive, a homopolymer of the 
polyfluoroalkyl group-containing polymerizable compound will be formed in 
addition to the block copolymer, whereby it becomes difficult to 
simultaneously obtain the mutually opposing properties. 
Various systems and conditions for the polymerization reaction may be 
employed for the production of the copolymer of the present invention. 
Namely, any one of the polymerization systems such as bulk polymerization, 
solution polymerization, suspension polymerization, emulsion 
polymerization, radiation polymerization or photo polymerization, may be 
employed. For instance, a method may be employed wherein a mixture of 
compounds to be copolymerized is emulsified in water in the presence of a 
surface active agent and copolymerized under stirring. As a polymerization 
initiating source, a polymerization initiator such as an organic peroxide, 
an azo compound or a persulfate, or an ionizable radiation such as 
.gamma.-rays, may be employed. As the surfactant, almost any one of 
various anionic, cationic or nonionic emulsifiers may be employed. Thus, a 
method may be employed wherein the polymerizable starting compounds are 
dissolved in a suitable organic solvent and subjected to solution 
polymerization by means of a polymerization initiating source (such as a 
peroxide or an azo compound soluble in the organic solvent used, or an 
ionizable radiation). The solvent suitable for the solution polymerization 
includes trichlorotrifluoroethane, tetrachlorodifluoroethane and 
methylchloroform. By such a solution polymerization or emulsion 
polymerization, an aerosol type, organic solvent type or latex type 
surface modifier can directly be produced. 
The surface modifier of the present invention can be applied to an object 
to be treated in an optional manner depending upon the type of the object 
to be treated, or upon the type of the formulation such as the solvent 
solution type or the aerosol type. For instance, in the case of an aqueous 
emulsion type or solvent solution type, a conventional method for coating 
treatment such as dipping or coating may be employed to apply it on the 
surface of the object to be treated, followed by drying. If necessary, it 
may be applied together with a suitable crosslinking agent, followed by 
curing. In the case of an aerosol type surface modifier, the application 
can be made by simply spraying it on the object to be treated, whereupon 
it immediately dries up to provide adequate properties. 
The surface modifier of the present invention can be used for various 
applications by virtue of its excellent surface modifying effects such as 
water repellency, oil repellency, stainproofing properties, lubricating 
properties and non-adhesiveness, for instance, as a water and oil 
repellant, a stainproofing agent, a lubricant, a releasing agent, an 
anti-blocking agent, an additive for coating compositions, and a leveling 
agent or a moisture proofing improver. 
There is no particular restriction as to the object to be treated by the 
surface modifier of the present invention, and various objects may be 
mentioned, including, for instance, fiber fabrics, glass, paper, wood, 
leather, wool, asbestos, bricks, cement, ceramics, metals and oxides, 
porcelains, plastics, coated surfaces and plasters. The fiber fabrics 
include fabrics of animal or plant natural fibers such as cotton, linen, 
wool or silk; fabrics of various synthetic fibers such as a polyamide, a 
polyester, a polyvinyl alcohol, a polyacrylonitrile, a polyvinyl chloride 
or a polypropylene; fabrics of semi-synthetic fibers such as rayon or 
acetate; fabrics of inorganic fibers such as glass fibers or asbesto 
fibers; and fabrics of mixtures of such fibers.

Now, the present invention will be described in further detail with 
reference to Examples. However, it should be understood that the present 
invention is by no means restricted to such specific Examples. 
REFERENCE EXAMPLE 1 
Into a 300 ml four-necked flask equipped with a stirrer and a Dean-Stark 
water separator, 15 g of a silicone having the formula: 
##STR4## 
2.7 g of thioglycol, 0.2 g of p-toluene sulfonic acid and 200 ml of 
toluene were introduced, and reacted under reflux for 4 hours. As 
azeotropic water, 0.54 g of water was distilled. 
After the removal of toluene, the residue was dissolved in 
1,1,2-trichloro-trifluoroethane (hereinafter referred to simply as R-113). 
After washing once with 20 ml of a 1% sodium carbonate aqueous solution, 
the solvent was distilled off from the organic layer to obtain a 
transparent oil (15.3 g, yield: 95.0%, IR: 1745 cm.sup.-1 (S)). 
REFERENCE EXAMPLE 2 
30 g of a silicone having the formula: 
##STR5## 
1.3 g of thioglycolic acid, 0.3 g of p-toluene sulfonic acid and 200 ml of 
toluene were charged, and the esterification reaction was conducted in the 
same manner as in Reference Example 1. After 0.22 g of water was distilled 
off, the same after-treatment was conducted (yield: 97.0). 
REFERENCE EXAMPLE 3 
Preparation of a Terminal-C.sub.3 H.sub.6 SH Containing Siloxane Chain 
Transfer Agent 
Into a 100 ml reactor equipped with a stirrer, 10.0 g (45.0 mmol) of 
hexamethylcyclotrisiloxane having the formula: 
##STR6## 
and 4.5 g (16.7 mmol) of 1,3-bis(3-mercaptopropyl)-tetramethyldisiloxane 
having the formula: 
##STR7## 
were charged, and heated to 60.degree. C. or higher. When the content 
became homongeneous, 0.20 g of sulfuric acid was added thereto, and the 
mixture was reacted for equilibrium at 100.degree. C. for 5 hour. Then, 50 
ml of R-113 was added to obtain a R-113 solution, which was washed twice 
with 20 ml of water. Then, R-113 was evaporated to obtain 12.8 g of a 
crude product. From the crude product, volatile components were removed 
under a reduced pressure of 0.1 mmHg at 180.degree. C. over a period of 2 
hours to obtain 8.6 g of purified siloxane (SH content: 5.0%, yield: 
59.3%) 
REFERENCE EXAMPLE 4 
Preparation of 
##STR8## 
Into a 100 ml reactor equipped with a stirrer, 7.8 g (35.0 mmol) of 
hexamethylcyclotrisiloxane, 16.4 g (35.0 mmol) of 
1,3,5-tris(3,3,3-trifluoropropyl)-1,3,5-trimethylcyclotrisiloxane having 
the formula: 
##STR9## 
and 6.9 g (24.6 mmol) of 1,3-bis(3-mercaptopropyl)-tetramethyldisiloxane 
were charged, and heated to 60.degree. C. or higher. When the content 
became homogeneous, 0.32 g of sulfuric acid was added, and the subsequent 
operation was conducted in the same manner as in Reference Example 3 to 
obtain 22.3 g of purified siloxane (SH content: 4.4%, yield: 71.7%). 
EXAMPLE 1 
Into a 100 ml ampoule, 20 g (35 mmol) of C.sub.9 --F.sub.19 --C.sub.2 
H.sub.4 OCOCH.dbd.CH.sub.2 (hereinafter referred to simply as FA), 1.15 g 
(1.0 mmol) of the mercapto group-containing silicone prepared in Reference 
Example 1, 49.4 g of R-113 and 0.2 g (0.3 mmol) of 
.alpha.,.alpha.-azobisisobutyronitrile (AIBN) were charged, and after 
flushing thoroughly with nitrogen, polymerized at 60.degree. C. for 13 
hours. The conversion of FA was confirmed to be at least 99% by gas 
chromatography. 
The copolymer solution thus obtained was diluted with R-113 to a solid 
content of 0.4%. A PET (doeskin) cloth was dipped therein, and dried in 
air and then in hot air at 100.degree. C. for 3 minutes. The treated cloth 
had a flexible texture, and a water repellency of 100 (JIS L-1005) and an 
oil repellency of 7 (AATCC TM-118-1966). After washing (JIS L-0217-103) 
three times [hereinafter referred to simply as HL3] and after dry cleaning 
(JIS L-1092-322) three times [hereinafter referred to simply as DC3], the 
oil repellency/the water repellency was 5/100 and 5/100, respectively. 
EXAMPLES 2 to 9 
FA, a methacrylate containing no fluorine and a mercapto group-containing 
silicone prepared in one of Reference Examples 1 to 4 were polymerized in 
the proportions as identified in Table 1 in the same manner as in Example 
1, and a PET cloth was treated therewith. The results are shown in Table 
1. 
COMATIVE EXAMPLE 1 
Only FA was charged as the monomer for polymerization, and the 
polymerization was conducted in the same manner as in Example 1, and a PET 
cloth was treated therewith. [Polymerization scale FA: 20.0 g (35 mmol), 
R-113: 45 g, AIBN: 0.2 g] 
COMATIVE EXAMPLE 2 
As the polymerizable monomer, 20 g (35 mmol) of FA and 3.0 g (0.91 mmol) of 
a silicone methacrylate having the formula: 
##STR10## 
were charged, and 47.0 g of R-113 and 0.2 g of AIBN were added. Then, the 
polymerization was conducted in the same manner as in Example 1, and then 
a PET cloth was treated therewith. 
TABLE 1 
__________________________________________________________________________ 
FA Other monomer 
Silicone OR/WR 
(mmol) (mmol) (mmol) Texture* 
Initial 
DC 3 HL3 
__________________________________________________________________________ 
Example 
2 35 0 Reference Example 1 
Flexible 
6/100 
6/100 
3/60 
0.5 
3 35 0 Reference Example 2 
Flexible 
6/100 
5+/80+ 
3+/60 
0.5 
4 35 0 Reference Example 2 
Flexible 
6/100 
5/80+ 
3+/60 
0.1 
5 25 StMA 10 Reference Example 1 
Flexible 
6/100 
3/70 5/100 
1.0 
6 35 AZMA 3 Reference Example 1 
Flexible 
6/100 
6/100 
6/100 
1.5 
7 35 SMA-1 3 Reference Example 1 
Flexible 
6/100 
5/80 5/100 
1.5 
8 35 0 Reference Example 3 
Flexible 
6/100 
6/100 
5/90 
1.0 
9 35 0 Reference Example 4 
Flexible 
6/100 
6/100 
6/90 
1.0 
Compara- 
35 0 0 Coarse and 
6/100 
5/80 4/50 
tive hard 
Example 1 
Compara- 
35 SAM-2 0.94 
0 Slightly 
6/100 
3/50- 
5-/60 
tive hard 
Example 2 
__________________________________________________________________________ 
*Texture was evaluated by touch sense. 
StMA . . . C.sub.18 H.sub.37 OCOC(CH.sub.3)CH.sub.2 
##STR11## 
SMA1 . . . (MeO).sub.3 SiC.sub.3 H.sub.6 OCOC(CH.sub.3)CH.sub.2 
##STR12## 
The surface modifier of the present invention comprising the block 
copolymer as an essential component, is capable of imparting high surface 
modifying effects such as water repellency, oil repellency, stainproofing 
properties, lubricating properties and non-adhesiveness to a substrate. 
Particularly, when used as a water and oil repellant for fibers, it serves 
as a treating agent capable of imparting flexibility and durability which 
are hardly simultaneously imparted by conventional treating agents.