Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2000-08-24
2002-06-25
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S447000, C428S480000, C428S482000, C428S500000, C428S520000, C427S372200, C427S384000, C427S385500, C427S387000, C525S100000, C525S123000, C525S165000, C525S191000, C525S221000, C525S222000, C525S437000, C525S440030, C525S444000, C525S452000, C525S457000
Reexamination Certificate
active
06410147
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally directed to low gloss coating compositions used as basecoats or clearcoats and more particularly directed to low gloss crosslinkable liquid coating compositions that produce low gloss coatings having smooth surfaces.
2. Description of Related Art
Coating compositions have long been used to produce coatings having desired coating characteristics. For instance, coating compositions have been used to enhance surface appearance, such as providing high gloss or low gloss. High gloss surfaces reflect a high proportion of the light directed at them specularly. By contrast, low gloss surfaces reflect a low proportion of the light directed at them specularly. Low gloss coatings that produce less image impairment are aesthetically more pleasing. In the past, coating compositions relied on including flatting agents, such as amorphous silicon dioxide, to produce low gloss coatings. By increasing the loading of the flatting agent in a coating composition, the gloss can be reduced. To attain low gloss in clear coats, coating compositions have to be loaded with an excess amount, typically more than 6 weight percent based on the total weight of the composition of the flatting agent. Unfortunately, the flatting agent in these excessively loaded coating compositions tends to coagulate. As a result, the conventional low gloss coatings resulting therefrom have visually unacceptable seedy appearance. Furthermore, the presence of the excessive amount of these flatting agents in a coating composition tends to make the resultant coatings more brittle than conventional coating compositions. Thus, a need exists for durable low gloss coatings that do not have seedy appearance. The present invention addresses the problem of conventional low gloss coatings having a seedy appearance by producing low gloss coatings that have smooth surface.
Attempts have been made to produce low gloss coatings. For example, the U.S. Pat. No. 4,921,776 teaches the use of a mixture of slightly incompatible polymers applied over photographs for producing low gloss substantially transparent protective films that are laminated to photographs. However, the use of such mixtures does not result in low gloss coatings having desired coating properties, such as those required for use in automotive topcoats or basecoats. Therefore, a need still exists for a coating composition that not produce a low gloss coating having desired coating properties, such as scratch and mar resistance.
STATEMENT OF THE INVENTION
The present invention is directed to a low gloss crosslinkable coating composition that produces a low gloss coating upon cure comprising:
(a) a binder component which comprises a combination of at least two partially compatible crosslinkable components retained in an evaporable medium, whereby said low gloss coating exhibits a 60° specular gloss that is at least 5% lower than gloss of coatings from coating compositions containing any one of said crosslinkable components, and
wherein the first of said crosslinkable components in said combination is:
(i) a polar polymer selected from the group consisting of a polar acrylic polymer having at least two crosslinkable functionalities, a polar polyester having at least two crosslinkable functionalities, polar polyurethane having at least two crosslinkable functionalities and a combination thereof; and
wherein the second of said crosslinkable components in said combination is:
(ii) a non-polar silane polymer, non-polar acrylic polymer having at least two crosslinkable functionalities, non-polar polyester having at least two crosslinkable functionalities, non-polar polyurethane having at least two crosslinkable functionalities or a combination thereof; and
(b) a crosslinking agent selected from the group consisting of monomeric melamine, polymeric melamine, polyisocyanate, and blocked polyisocyanate.
The present invention is also directed to a method of producing a low gloss coating on a substrate, said method comprising the steps of:
(I) applying a layer of a low gloss crosslinkable coating composition comprising:
(a) a binder component which comprises a combination of at least two partially compatible crosslinkable components retained in an evaporable medium, whereby said low gloss coating exhibits a 60° specular gloss that is at least 5% lower than gloss of coatings from coating compositions containing any one of said crosslinkable components, and
wherein the first of said crosslinkable components in said combination is:
(iii) a polar polymer selected from the group consisting of a polar acrylic polymer having at least two crosslinkable functionalities, a polar polyester having at least two crosslinkable functionalities, polar polyurethane having at least two crosslinkable functionalities and a combination thereof; and
wherein the second of said crosslinkable components in said combination is:
(iv) a non-polar silane polymer, non-polar acrylic polymer having at least two crosslinkable functionalities, non-polar polyester having at least two crosslinkable functionalities, non-polar polyurethane having at least two crosslinkable functionalities or a combination thereof; and
(b) a crosslinking agent selected from the group consisting of monomeric melamine, polymeric melamine, polyisocyanate, and blocked polyisocyanate;
(II) evaporating said medium from said layer; and
(III) curing said layer into said coating, which has a surface reflectance of less than 70 when measured at 60° angle of incidence under ASTM D-523-67.
The present invention is also directed to a low gloss coating on a substrate produced from the aforedescribed low gloss crosslinkable coating composition.
DETAILED DESCRIPTION OF THE INVENTION
As used herein:
“Crosslinkable components” refer to monomers, oligomers or polymers that are provided with one or more crosslinkable functionalities. These crosslinkable functionalities can be pendant from or in the backbone of the component. The term “crosslinkable functionalities” relates to those functionalities present in the component that, during cure, react with other crosslinkable functionalities present in another component of the coating composition to form a crosslinked structure.
“Two-pack coating composition” means a solvent borne crosslinkable coating composition comprising two or more crosslinkable components stored in separate containers. These containers are typically sealed to increase the shelf life of the components of the coating composition. The components are mixed prior to use and applied as a layer, typically through a spray nozzle, of desired thickness on a substrate surface, such as an autobody. After application, the solvent from the layer evaporates and the layer cures under ambient conditions, or it can be UV cured, or bake cured at elevated temperatures to form a coating on the substrate surface having the desired coating properties, such as desired gloss, scratch resistance and resistance to environmental etching.
“One-pack coating composition” means a solvent borne crosslinkable coating composition comprising two or more crosslinkable components that are stored in the same container. The crosslinkable functionalities on one or more of the crosslinkable components are not reactive at the storage temperature. After application of a layer of the one-pack coating composition on a substrate, the layer is exposed to elevated temperatures to form a coating having the desired coating properties, such as desired gloss, scratch resistance and resistance to environmental etching.
“Crosslinkable component solid” refers to the solid portion a crosslinkable component that remains after removing the evaporable portion.
“Low gloss coating” refers to a coating having a surface with a reflectance of less than 70, preferably less than 40, more preferably in the range of from 20 to 50 when measured at 60° angle of incidence under ASTM D-523-67 test with a glossimeter supplied by Byk-Gardner.
“Compatibility” means the ability of two or more crosslinkable componen
Chung Ding-Yu
Hazan Isidor
Paquet, Jr. Donald Albert
Chen Vivian
Deshmukh Sudhir G.
E. I. du Pont de Nemours and Company
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