Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2002-07-18
2004-05-11
Tucker, Philip (Department: 1712)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C428S407000, C428S447000, C428S450000, C428S523000, C428S702000, C528S025000, C528S026000, C528S027000, C528S028000, C528S030000, C528S032000, C528S043000
Reexamination Certificate
active
06733884
ABSTRACT:
This invention relates generally to a polymer compound having a silicon ester moiety. In particular, the polymer compound has a group containing a silicon ester moiety located at one end of the polymer compound. Further, the polymer compound also contains functional groups that are pendant to the backbone of the polymer compound. The polymer compound is useful as a coupling agent for treating the surfaces of inorganic substrates to modify the surface properties or to provide inorganic surfaces with functional groups. Also provided is a process for preparing the polymer compound.
Silane coupling agents are widely used to improve the properties of materials containing interfaces between an inorganic substance and an organic substance, such as polymeric coatings applied onto metal or metal oxide surfaces, or polymeric coatings having inorganic pigment particles dispersed within. Treatment of inorganic surfaces with silane coupling agents improves the interfacial bond between the inorganic material and the organic material, resulting, for example, in coatings with better adhesion to metal oxide surfaces or improved compatibility of inorganic particles in a polymer. Silane coupling agents are characterized as containing hydrolyzable silane groups attached to an organic group. The hydrolyzable silane groups react to form covalent bonds with the surface of an inorganic substance, attaching organic groups to the inorganic substance, and thus modifying the surface properties of the inorganic substance. The attached organic group typically provides improved compatibility with organic materials such as polymers. Silane coupling agents are employed for modifying the surface characteristics of inorganic particles to provide better dispersibility into plastics.
For example, U.S. Pat. No. 4,061,503 discloses the treatment of titanium dioxide particles with a polyether substituted silicon compound as the coupling agent. The polyether substituted silicon compound contains a hydrolyzable silicon group attached to a polyalkylene oxide group. The titanium dioxide treated with the polyether substituted silicon compound is disclosed to have improved compatibility or dispersibility within a plastic or resin system. However, the polyether substituted silicon compounds are not disclosed to form covalent bonds with the plastic or resin system.
Coupling agents are desired that can provide covalent bonding between the interface of an inorganic material and an organic material. The formation of covalent bonding between the inorganic-organic interface allows the formation of composites having improved properties, compared to composites based on weaker molecular interactions, such as compatibility arising from dispersion forces or hydrogen bonding.
In the present invention, a polymer compound is provided having a reactive group for forming a covalent bond to an inorganic substrate and at least one functional group, which is capable of reacting with a second substrate, such as a polymer, having a complementary functional group to form a covalent bond with the second substrate. The polymer compound has an organic polymer component that is prepared from ethylenically unsaturated monomer and has at least one functional group pendant to the backbone of the organic polymer component. The polymer compound is useful for modifying the surface properties of inorganic materials, such as providing inorganic particles with improved water dispersibility, and for forming composite particles containing inorganic particles surrounded by covalently bonded polymer particles. The composite particles prepared with the polymer compound of this invention are useful in coatings, especially to provide coatings that have improved hiding compared to conventional coatings.
According to the first aspect of the present invention, a polymer compound is provided containing an organic polymer component having ethylenically unsaturated monomers as polymerized units and having at least one pendant functional group; and a semi-telechelic group having a silicon ester moiety and a sulfur atom forming a bond to the organic polymer component.
A second aspect of the present invention provides a process for preparing a polymer compound including the steps of preparing a reaction mixture comprising at least one ethylenically unsaturated monomer having a functional group and a mercaptan compound having a silicon ester moiety; polymerizing the reaction mixture to form the polymer compound; wherein the polymer compound contains an organic polymer component containing, as polymerized units, the ethylenically unsaturated monomer having a functional group; and a semi-telechelic group formed from the mercaptan compound, and having a sulfur atom forming a bond to the organic polymer component.
A third aspect of the present invention provides a surface-treated inorganic substrate including an inorganic substrate having a surface; and a residue of a polymer compound containing an organic polymer component having ethylenically unsaturated monomers as polymerized units and having at least one pendant functional group; and a semi-telechelic group having: a sulfur atom forming a bond to the organic polymer component, and at least one reacted silanol group forming a covalent bond with the surface of the inorganic substrate.
As used herein, the term “(meth)acrylate” refers to either acrylate or methacrylate and the term “(meth)acrylate” refers to either acrylic or methacrylic.
A covalent bond is a bond between two atoms formed by sharing at least one pair of electrons and expressly excludes ionic bonds, bonds formed by adsorption including chemical adsorption and physical adsorption, van der Waals bonds, or bonds formed by dispersion forces.
The polymer compound of the present invention includes a polymer chain, referred to herein as the “organic polymer component”, and a group attached to one end of the organic polymer component, referred to herein as the “semi-telechelic group”. The semi-telechelic group bears at least one silicon ester moiety. The polymer compound is characterized by the following general formula:
A—L—S—Q
wherein Q is the organic polymer component, A—L—S is the semi-telechelic group, A is the silicon ester moiety, L is a linker group, and S is a sulfur atom. In the presence of water, the silicon ester moiety reacts to form at least one silanol group. The silanol group is reactive with inorganic surfaces such as metal and metal oxide surfaces and forms a covalent bond with the inorganic surface to adhere the reacted polymer compound onto the inorganic surface. The attachment of the reacted polymer compound to the inorganic surface allows the modification of the surface properties of the inorganic surface.
The semi-telechelic group contains the linker group and at least one silicon ester moiety. The semi-telechelic group also contains a sulfur atom, which provides a bond between the linker group and the end of the organic polymer component. The linker group contains at least one carbon atom and is typically a divalent group, which is either oxygen or carbon bonded to the silicon atom of the silicon ester moiety. Preferred is a linker group that is carbon bonded to the silicon atom of the silicon ester moiety. Suitable linker groups include alkenyl groups such as:
—CH
2
—
—CH
2
—CH
2
—
—CH
2
CH
2
CH
2
—
—CH(CH
3
)CH
2
—
and aryl groups such as:
—CH
2
—C
6
H
4
—CH
2
CH
2
—
The bond between the linker group and the silicon ester moiety is materially stable to hydrolysis under the conditions employed to hydrolyze the silicon ester moiety to form silanol. The semi-telechelic group contains one or more silicon ester moieties. Preferred is a semi-telechelic group having one silicon ester moiety.
The silicon ester moiety has an oxygen atom forming a bond between a silicon atom and an organic group and is characterized by the following general formula:
(R
1
O)
n
(R
2
)
3−n
Si—
wherein R
1
and R
2
are organic groups containing at least one carbon atom, and n has an integer value in the range of 1 to 3. Examples of R
1
include alkyl groups such as
Feely Michael J
Greenblatt Gary D.
Rohm and Haas Company
Tucker Philip
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