Coating processes – Restoring or repairing
Reexamination Certificate
2001-07-31
2003-09-23
Dawson, Robert (Department: 1712)
Coating processes
Restoring or repairing
C524S405000, C524S497000, C524S588000, C524S493000, C524S430000, C106S287100, C525S474000, C525S477000, C528S075000, C528S028000, C528S029000, C528S034000, C528S027000, C528S026000, C528S038000, C528S039000
Reexamination Certificate
active
06623791
ABSTRACT:
FIELD OF THE INVENTION
Certain embodiments of the present invention are directed to coating compositions comprising at least one reactive functional group-containing polysiloxane, at least one reactant comprising at least one functional group that is reactive with the functional group(s) of the polysiloxane, and at least one boron-containing compound selected from boric acid, boric acid equivalents and mixtures thereof. Other embodiments of the present invention are directed to cured coatings formed from the foregoing coating compositions. Further embodiments are directed to substrates coated with the aforementioned compositions.
BACKGROUND OF THE INVENTION
Color-plus-clearcoating systems involving the application of a colored or pigmented basecoat to a substrate followed by application of a transparent or clearcoat over the basecoat have become increasingly popular as original finishes for a number of consumer products including, for example, automotive vehicles. The color-plus-clearcoating systems have outstanding appearance properties such as gloss and distinctness of image, due in large part to the clearcoat. Such color-plus-clearcoating systems have become popular for use with automotive vehicles, aerospace applications, floor coverings such as ceramic tiles and wood flooring, packaging coatings and the like.
Topcoat coating compositions, particularly those used to form the transparent clearcoat in color-plus-clear coating systems for automotive applications, are subject to defects that occur during the assembly process as well as damage from numerous environmental elements. Such defects during the assembly process include paint defects in the application or curing of the basecoat or the clearcoat. Damaging environmental elements include acidic precipitation, exposure to ultraviolet radiation from sunlight, high relative humidity and high temperatures, defects due to contact with objects causing scratching of the coated surface, and defects due to impact with small, hard objects resulting in chipping of the coating surface.
Further, elastomeric automotive parts and accessories, for example, elastomeric bumpers and body side moldings, are typically coated “off site” and shipped to automobile assembly plants. The coating compositions applied to such elastomeric substrates are typically formulated to be very flexible so the coating can bend or flex with the substrate without cracking. To achieve the requisite flexibility, coating compositions for use on elastomeric substrates often are formulated to produce coatings with lower crosslink densities or to include flexibilizing adjuvants which act to lower the overall film glass transition temperature (Tg). While acceptable flexibility properties can be achieved with these formulating techniques, they also can result in softer films that are susceptible to scratching. Consequently, great expense and care must be taken to package the coated parts to prevent scratching of the coated surfaces during shipping to automobile assembly plants.
U.S. Pat. No. 6,235,858 B1 discloses carbamate and/or urea functional polymers for use in coating compositions, especially clear coating compositions for color-plus-clear coating systems. Such polymers provide coatings with good resistance to damage caused by acidic precipitation.
U.S. Pat. No. 5,853,809 discloses clearcoats in color-plus-clear systems which have improved scratch resistance due to the inclusion in the coating composition of inorganic particles such as colloidal silicas which have been surface modified with a reactive coupling agent via covalent bonding.
A number of patents disclose the use of a surface active material, for example, a polysiloxane, in coating compositions to improve mar resistance of the cured coatings. U.S. Pat. Nos. 5,939,491 and 6,225,434B1 disclose coating compositions comprising organic polysiloxanes having reactive functional groups. These polysiloxanes provide coatings with improved mar and scratch resistance.
A number of patents disclose the use of boric acid in polymeric compositions. For example, U.S. Pat. Nos. 5,951,747 and 6,059,867 discloses the use of boric acid and borates in conjunction with a succinate in non-chromate, corrosion-inhibiting coating compositions for improved adhesion to metallic surfaces. Such compositions further include inhibitors such as phosphates, phosphosilicates, silicates, titanates, and zinc salts. U.S. Pat. No. 4,832,990 discloses a process for improving adhesion of polyolefins to metal substrates comprising mechanical cleaning of the metal surface, treating the metal surface with a water-alcohol solution containing an alkoxysilane and boric acid, thermally treating the acid treated substrate, and subsequently treating the substrate with a polyolefin-based composition comprising zeolites and carbon black pigment. U.S. Pat. No. 5,073,455 discloses a thermoplastic laminated film which has improved adhesion to hydrophilic polymers, hydrophobic polymers and inorganic substances. The film comprise a base film of thermoplastic resin and a layer formed on the base film comprising a composition of one or more of water-soluble resins, water emulsified resins and water-dispersible resins, and an organic boron polymer or a mixture composed of an organic boron polymer and vinyl alcohol.
Multi-layer composite coatings are commonplace in modern coating lines. For example, a typical automotive coating system can include the sequential application of an electrodeposition primer, a primer-surfacer, a color enhancing base coat, and a transparent top coat. In some instances, the electrodeposition primer is applied over a mill-applied weldable, thermosetting coating which has been applied to the coiled steel metal substrate from which the automobile body (or body parts, such as fenders, doors and hoods) has been formed. Also, adhesive coatings, for example, windshield adhesives, trim and molding adhesives and structural adhesives are sometimes applied to the cured top coats where necessary. Due to these multi-layer composite coating processes, it is necessary that the previously applied coating layer have excellent intercoat or interlayer adhesion to the subsequently applied coating layer(s).
Although the aforementioned coating compositions exhibit improvements for acid etch resistance and mar and scratch resistance, such compositions may not be readily recoatable. That is, when a subsequent coating is applied to the cured mar and scratch resistant coating composition, the intercoat adhesion between the cured coating and the subsequently applied coating can be quite poor.
For example, as mentioned above, on most vehicle coating lines the vehicle body is first given a corrosion inhibitive electrodepositable primer coating commonly formed from a cationic electrodepositable coating composition. This electrodeposition primer is fully cured and, a primer-surfacer is typically applied to the cured electrodeposition primer. The primer-surfacer serves to enhance chip resistance of subsequently applied top coatings as well as to ensure good appearance of the top coatings. The top coats, either a monocoat or a color-plus-clear system, are then applied to the cured primer-surfacer coating. While most top coats have excellent intercoat adhesion to the primer-surfacer coating, some top coating compositions inherently can exhibit intercoat adhesion problems with some primer-surfacer coatings.
Also, due to the interest in cost-savings, there is recent interest in the automotive coatings market in eliminating the primer-surfacer step altogether. That is, the top coats can be directly applied to the cured electrodeposition primer. In such modified coating processes, the electrodeposition primer is required to meet stringent durability and appearance specifications. Moreover, the cured electrodepositable primer must have excellent intercoat adhesion to the subsequently applied top coats (either monocoats or color coats of a color-plus-clear system).
On commercial automobile coating lines during application of the coating system, certain portions of the line ca
Anderson Lawrence G.
Hockswender Thomas R.
Sadvary Richard J.
Tyebjee Shiryn
Altman Deborah M.
Dawson Robert
Peng Kuo-Liang
PPG Industries Ohio Inc.
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