Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-01-31
2002-03-05
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S535000, C524S567000, C524S568000, C252S008610, C252S008620, C427S393500
Reexamination Certificate
active
06353051
ABSTRACT:
BACKGROUND OF THE INVENTION
Synthetic grain leather generally comprises three layers, a base resin-treated fabric substrate, a skin layer containing resin and optional additives such as pigments, and a top coating. The resins are poly(vinyl chloride), or more preferably polyurethane. Such polyurethane grain leathers are described by Sugawara in Kokai Patent No. Sho 54(1979)-18991 and by Civardi and Hutter in the Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 14, pp. 231-249, (John Wiley & Sons, Inc., New York N.Y., 1981, ISBN 0-471-02067-2) under “Leatherlike Materials.” While the top coatings for polyurethane synthetic leathers can be prepared from either water-based or solvent-based polyurethane resins, the molecular weight of the water-based polyurethane resin is typically much lower than for solvent-based polyurethane resin. Therefore, the physical properties of water-based polyurethane top coatings are less suitable for synthetic leather applications than are the physical properties of top coatings made from solvent-based polyurethane resins. Solvent-based polyurethane resins are consequently the main materials for the manufacture of synthetic leathers.
Solvent-based polyurethane resins are widely used in the manufacture of man-made grain leather materials. Such synthetic leather materials are used to fabricate a wide range of consumer products, including such items as clothing, shoes, and accessories. In such uses, a high level of oil and water repellency is desirable. The oil repellency provides soil resistance.
In the prior art, a number of methods have been developed to improve physical water resistance, and thus the hydrolysis resistance, of polyurethane-based grain leathers. Such methods are discussed by Sugawara (op. cit.), Civardi and Hutter (op. cit.), Koniki in Japanese Examined Patent Application Publication (Kokoku) No; Heisei 4-53, 985, and by Tonelli and Simeone in U.S. Pat. No. 5,410,010. Typically, these treatments comprise the application of a top coating to the skin layer of the synthetic grain leather. The top coatings have included the coating of the material with formulations containing silicones, hydrocarbon waxes, or fluorochemicals. Silicone and hydrocarbon wax coatings provide negligible oil repellency and soil resistance. Mixtures of water-based fluoropolymer resin dispersions and water-based polyurethane resin emulsions have been coated on the skin layer of synthetic grain leather to improve water resistance (Sugawara, op. cit.). The function of these prior art coatings has been to improve hydrolysis resistance.
A particular type of water resistance not provided by prior art compositions is desirable, termed “dynamic water repellence.” Dynamic water repellence, further defined below, is a characteristic property that allows the surface to both resist wetting and to shed water rapidly. The practical advantage of this property is that rain, or splashed water, is immediately shed and the surface of the article retains the attractive glossy surface of the grain leather. It should be noted that there is a major difference between hydrolysis resistance, a surface property intended to preserve the properties of the synthetic leather itself, and dynamic water repellence, a surface property that causes water to be shed rapidly from the surface and provides hydrolysis resistance and a desirable esthetic property.
It is desirable to have an improved solvent-based polyurethane top coating that simultaneously maintains good oil repellency but also provides a high level of dynamic water repellency for use in the manufacture of synthetic grain leather. The present invention provides such a top coating composition.
SUMMARY OF THE INVENTION
The present invention comprises a composition for coating synthetic grain leather comprising:1) i) a copolymer in solvent prepared by polymerization of at least one monomer A, at least one monomer B, and at least one monomer selected from the group consisting of monomer C, monomer D and monomer E, ii) a blend of at least two of said copolymers, or iii) a blend of at least one of the above copolymers with at least one copolymer formed from at least one monomer A, at least one monomer C, and at least one monomer selected from the group consisting of monomer D and monomer E wherein monomer A is selected from the group consisting of Formula A1, Formula A2, and Formula A3, or a mixture thereof, wherein
Formula A1 is
MO[(CHR
1
)
x
(CH
2
)
y
O]
z
—(CH
2
)
w
—(T)
v
—C(O)—CR═CH
2
(Formula A1)
wherein
M is H or CH
3
(CH
2
)
r
—, where r is 0 to 5,
(x+y) is 2 to 6 wherein x is zero or a positive integer and y is a positive integer,
R
1
is hydrogen, fluorine, or an optionally halogenated C
1
or C
2
alkyl group, such as ethyl, methyl, chloromethyl,
z is 3 to 22 or mixtures thereof,
v is 0 or 1,
w is 0 to 6, provided that when w is 0, v is 0;
T is —O— or —NR
2
—, wherein R
2
is CH
3
(CH
2
)
q
and q is 0 to 4, and
R is hydrogen or a C
1
-to C
4
alkyl group, and preferably hydrogen or methyl;
Formula A2 is
(R
3
R
4
)N—(CH
2
)
b
—A—C(O)—CR═CH
2
(Formula A2)
wherein
R
3
and R
4
are independently C
1
to C
4
alkyl, hydroxyethyl, benzyl, or R
3
and R
4
together with the nitrogen atom form a ring structure morpholine, pyrrolidine or piperidine.
b is 2 to 8 or mixtures thereof,
A is —O— or —NR
2
—, wherein R
2
is as defined above, and
R is as defined above; and
Formula A3 is
X
−+
N(R
3
R
4
R
5
)—(CH
2
)
b
—A—C(O)—CR═CH
2
(Formula A3)
wherein
R
5
is H, C
1
to C
4
alkyl,
R
3
and R
4
are as described above, or R
3
, R
4
and R
5
together with the nitrogen atom form an aromatic ring pyridine,
X is a chloride, bromide, hydroxide, sulfate or carboxylate anion, and
b, A, and R are as described above;
monomer B is a linear or branched fluoroalkyl (meth)acrylate of Formula B
C
g
F
(2g+1)
—Z—O—C(O)—CR═CH2 (Formula B)
wherein
g is 4 to 20 or mixtures thereof,
R is as previously defined, and
Z represents the grouping
wherein
h is 1 to 4, and
R is as previously defined, and
R
6
is a C
1
to C
4
alkyl group;
monomer C is selected from the group consisting of Formula C1 and Formula C2, or a mixture thereof,
wherein Formula C1 is
C
p
H
(2p+1)
—T—C(O)—CR═CH
2
(Formula C1)
wherein
p is 4 to 22 or mixtures thereof,
R and T are as previously defined; and
Formula C2 is
R
6
—[Si(R
6
R
7
)—O]
m
—[Si(R
6
)
2
—O]
n
—[(CH2)
d
—O]
e
—C(O)—CR═CH
2
(Formula C2)
wherein
each R
6
is independently a C
1
to C
4
alkyl group,
R
7
is R
6
or a C
1
to C
20
halogenated alkyl group,
(m+n) is 4 to 40 wherein m is zero or a positive integer and n is a positive integer,
d is 0 to 8,
e is zero or 1, provided that when d is zero, e is zero, and
R is as defined above;
monomer D is a cross-linking agent;
monomer E is vinyl chloride or vinylidene chloride; and
2) a polyurethane resin in solvent
The present invention further comprises a method of treating synthetic grain leather comprising application to the top surface thereof an effective amount of a composition as described above.
The present invention further comprises a synthetic grain leather treated in accordance with the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The top coating composition of the present invention comprises a copolymer, prepared, for instance, by aqueous emulsion polymerization in the presence of a surfactant, dispersed in a solvent or solvent mixture, and mixed with a solution of a polyurethane resin in a solvent. The top coating typically has high compatibility with the solvent-based polyurethane substrate onto which it is applied. The present invention further comprises a method of treating synthetic grain leather comprising application of a top coating composition of this invention to a pre-formed synthetic grain leather made from solvent-based polyurethane or from poly(vinyl chloride), and drying and curing the top coating. The invention further comprises such top coated substrates.
E. I. du Pont de Nemours and Company
Yoon Tae H.
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