Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-12-20
2001-12-11
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S026000, C528S017000, C528S035000, C528S012000, C528S503000, C528S483000, C528S483000, C528S106000, C528S287000
Reexamination Certificate
active
06329489
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns a composition comprising reactive silane oligomers having low polydispersity, viscosity and volatility. Such oligomers are useful for multi-component silicon modified organic coatings with low volatile organic content (VOC), improved mar and etch resistance.
A number of clear and pigmented coating compositions are utilized in various coatings, such as, for example, automotive coatings. Such coatings, typically applied as OEM coatings (original equipment manufacturer), are generally solvent based. However, due to increasing concern over the excessive release of volatile organic component (VOC) in the atmosphere, significant research is being conducted for developing low VOC, solvent-based coating compositions, generally with less than 0.6 kilograms of organic solvent per liter of coating composition (5 pounds per gallon), as determined under ASTM D3960 Test.
One of the approaches used in reducing the amount of VOC released by a coating composition during its application on a substrate, such as an automobile body, involves adding a silicon-containing reactive diluent to the coating composition. A number of patents disclose low VOC silicon-containing curable coating compositions, such as, for example, U.S. Pat. No. 4,467,081.
However, none of the approaches disclosed in the prior art improves miscibility in multi-component formulations while still maintaining optimum balance of coating properties, such as good mar and chemical resistance, high gloss and durability. Further limiting factor in the use of silane-based reactive diluents in coating compositions is the poor process control of silane functionalities during the preparation of conventional reactive diluents, which results in a broad distribution of silane functionalities.
The present invention overcomes the foregoing problems, by providing low VOC silane-based coating compositions that result in coatings having improved mar, chemical and environmental etch resistance, appearance and durability while still providing improved miscibility in multi-component formulations, as compared to conventional coating compositions.
STATEMENT OF INVENTION
The present invention is directed to a process for making a reactive silane oligomer, said process comprising:
contacting one or more unsymmetrical difunctional silane monomers with water, with one or more diol monomers, or with a combination thereof, wherein:
said diol monomer is:
R
1
—(OH)
2
,
wherein R
1
is selected from the group consisting of:
a) C
2
to C
20
alkylene, cycloaliphatic rings or aromatic rings, each optionally substituted with at least one member selected from the group consisting of O, N, P and S;
b) two or more cycloaliphatic or aromatic rings connected to each other through a covalent bond, or through an alkylene group of 1 to 5 carbon atoms, or through a heteroatom, or fused together to share two or more carbon atoms, each optionally substituted with at least one member selected from the group consisting of O, N, P and S; and
c) a linear polyester, branched polyester, a combination of said linear and said branched polyesters, polyacrylate, polyolefin, polyether, polycarbonate, polyurethane, or polyamide, each having a GPC weight average molecular weight in the range of from about 200 and 10,000; and
said difunctional silane monomer is:
wherein Cp is a primary carbon atom, Cs is a secondary carbon atom and R
2
is selected from the group consisting of:
a) C
3
to C
20
alkylene, C
1
, to C
10
alkyl substituted cycloaliphatic rings or C
1
, to C
10
alkyl substituted aromatic rings, each optionally substituted with at least one member selected from the group consisting of O, N, P and S;
b) C
1
, to C
10
alkyl substituted two or more cycloaliphatic rings, or C
1
to C
10
alkyl substituted two or more aromatic rings connected to each other through a covalent bond, or through an alkylene group of 1 to 5 carbon atoms, or through a heteroatom, or fused together to share two or more carbon atoms, each optionally substituted with at least one member selected from the group consisting of O, N, P and S; and
c) a combination of (a) and (b);
R
3
, R
4
and R
5
each is independently selected from the group consisting of:
Hydrogen, C
1
, to C
20
alkyl, C
1
, to C
10
alkyl substituted cycloaliphatic rings or C
1
, to C
10
alkyl substituted aromatic rings, each optionally substituted with at least one member selected from the group consisting of O, N, P and S;
X
P
and X
S
being independently selected from the group consisting of alkoxy containing 1 to 20 carbon atoms, acyloxy containing 1 to 20 carbon atoms, phenoxy, halogen, amine, amide, urea, imidazole, carbamate, ketoximine, oxazolidinone, and a combination thereof; and
Y
P
and Y
S
being independently selected from the group consisting of alkyl containing 1 to 12 carbon atoms, alkoxy containing 1 to 20 carbon atoms, acyloxy containing 1 to 20 carbon atoms, phenoxy, halogen, amine, amide, urea, imidazole, carbamate, oxazolidinone, and a combination thereof;
for producing said reactive silane oligomer having a GPC weight average molecular weight of less than 10,000 and having a polydispersity of less than
3
.
The present invention is also directed to a reactive silane oligomer of the formula:
when the unsymmetrical difunctional silane monomer is contacted with the diol monomer in the foregoing process.
The present invention is also directed to a reactive silane oligomer of the formula:
when the unsymmetrical difunctional silane monomer is contacted with water in the foregoing process.
The present invention is further directed to a coating composition containing the reactive silane polymer made in accordance with the foregoing process.
The present invention advantageously provides for a low VOC coating composition having high solids content.
The process of the present invention optimally and efficiently converts the reactants into a reactive silane oligomer having lower polydispersity, viscosity and volatility than a conventional silane oligomer.
The process of the present invention further advantageously produces a reactive silane oligomer having a low GPC weight average molecular weight of less than 10,000. Such a reactive silane oligomer, when included as a reactive diluent in a coating composition, lowers VOC while simultaneously increasing the solids content of the composition. As a result, users can efficiently apply such coating compositions by conventional means, such, as by spraying, dipping, roller coating, brushing or by electro-coating, and still produce durable coatings with low mar, etch and chemical resistance, and glossy appearance on conventional substrates, such automotive bodies.
DETAILED DESCRIPTION OF THE INVENTION
As used herein:
“High solids composition” is a coating composition having more than 40 weight percent, preferably in the range of from 60 to 100 weight percent of total solids based on the total weight of the composition.
“Low VOC composition” is a coating composition having less than 0.6 kilograms of solvent per liter of the coating composition.
“Low viscosity composition” is a coating composition having viscosity in the range of from 1 to 10,000 centipose as measured under ICI cone and plate viscometer.
“GPC weight average molecular weight” means weight average molecular weight as determined by gel permeation chromatography (GPC) using polystyrene standard.
“Polydispersity” means GPC weight average molecular weight divided by GPC number average molecular weight.
“Reactivity” means a degree of chemical activity of silane groups attached to carbon atoms in the backbone of a silane monomer.
“Primary carbon atom (Cp)” is a carbon atom in the backbone, shown below, of an unsymmetrical difunctional silane monomer having only one carbon atom attached to it.
“Secondary carbon atom (Cs)” is a carbon atom in the backbone of the unsymmetrical difunctional silane monomer, shown below, having one hydrogen atom and two carbon atoms attached to it.
It is believed, without reliance thereon, that the presence of two carbon attached to Cs, due
Gregorovich Basil V.
Hazan Isidor
Matheson Robert R.
Wilczek Lech
Dawson Robert
Deshmukh Sudhir G.
E. I. Du Pont de Nemours and Company
Peng Kuo-Liang
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