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
2000-03-24
2001-10-02
Michl, Paul R. (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...
Reexamination Certificate
active
06297312
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to adhesive coatings, and more specifically to aqueous or waterborne adhesion coatings, and methods of making and using the same.
The demand for olefinic resins, e.g. polyethylene (PE) and polypropylene (PP), in the automotive industry is increasing. In 1998, the automotive industry used 274 million pounds of olefinic resins to coat plastic substrates. By 2005, the automotive industry is projected to use an estimated 750 million pounds of olefinic resins per year.
Thermoplastic olefins (TPOs), mixtures of polypropylene (PP), ethylene-propylene-diene (EPDM), rubber and talc, are fast replacing steel components such as grills, lamp hole covers, automotive bumpers and side body panels. TPO components are less expensive, softer, less dense, easier to mold, easier to recycle and resist corrosion better than their steel counterparts.
TPO poses a significant problem. TPO does not easily adhere to standard one-component (1K) or two-component (2K) coatings. The polypropylene present in TPO creates a low free energy, non-polar surface which hinders bonding.
In an effort to solve this problem, polyolefinic and other plastic substrates have been coated with coating systems containing organic solvents. This solution is undesirable for two reasons: 1) organic solvents are toxic to the environment (high volatile organic compounds) and 2) organic solvents are expensive for waste treatment.
Using an adhesion promoter, namely chlorinated polyolefin (CPO), to bond with the non-polar surface has been proposed, for example in U.S. Pat. No. 4,954,573 (incorporated by reference). Several processes have been proposed to eliminate or minimize the application of CPO adhesion promoters to reduce volatile organic compounds (VOCs) associated with the process and the overall production costs.
U.S. Pat. No. 5,693,423, incorporated by reference, discloses a waterborne coating containing TPO which uses a CPO resin, an ethylene glycol, a surfactant, and an aliphatic amine.
U.S. Pat. No. 4,981,730, incorporated by reference, discloses a low VOC (about 3.5 pounds/gallon) aqueous composition which is suitable as a primer coating on a non-porous substrate such as plastic.
The following United States patents, which are incorporated by reference herein, relate more generally to coating compositions for plastic substrates, including polyolefin substrates: U.S. Pat. Nos. 5,198,485; 5,258,444; 5,288,780; 5,300,363; 5,425,926; 5,427,856; 5,709,946; and 5,777,022.
SUMMARY OF THE INVENTION
There is a continuing interest in providing an improved single coat, aqueous based plastic coating with a reduced level of VOCs. The compositions and methods of the present invention preferably employ a) a resin, b) a modified anionic polyurethane dispersion blend, c) coalescing agents, d) an anionic surfactant, e) wetting and dispersing additives, and f) a surface tension reducer. In another embodiment the compositions and method further employ a preservative, pigment and fillers.
The advantages of the invention are: (a) an easy to use single coat application, (b) minimal required cleaning of the plastic substrates, (c) eliminates a separate CPO step and subsequent coating steps (basecoat and topcoat), (d) reduced levels of VOCs, (e) reduced curing temperature, (f) increased durability and stability, (g) low odor, and (h) easy to handle and clean.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the preferred embodiments and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the invention will now be described with reference to various examples of how the invention can best be made and used.
The present invention provides one-pack aqueous or waterborne adhesion compositions useful in coating polyolefinic-containing substrates. In particular, the compositions are ideal for hard to adhere plastics such as TPO and PP. The one-pack waterborne primer compositions or systems, characterized by a VOC content of about 0.4 to about 2.0 lbs/gal, comprise:
(a) a halogenated polyolefinic resin;
(b) a modified anionic polyurethane dispersion blend;
(c) coalescing agents;
(d) an anionic surfactant;
(e) wetting and dispersing additives; and,
(f) surface tension reducers.
Preferably, the compositions and method of the present invention further employ a preservative, pigments and fillers.
The present compositions can form strong and flexible bonds between the coating and the plastic substrate without the aid of an adhesion promoter step.
The adhesion coatings provided by the compositions and methods of the present invention may be decorative, protective, or both. The coatings provided are capable of bonding with other materials such as a basecoat or a clearcoat layer, for example an acrylic, styrene butadiene rubber, polyurethane, epoxy, nitrile butadiene rubber, polyvinyl butyral or mixtures thereof. The coatings may be applied or deposited by any conventional method, such as airless, air-assisted airless gun or HVLP (high volume, low pressure) gun and spray-painting robot, thereby producing a multilayered article.
The present composition of one-pack waterborne primers or surfacers with direct adhesion to TPO achieves strong solvent-borne performance without the excessive use of aromatic solvents such as benzene, xylene and toluene.
The VOC content of the present invention is more environmentally friendly than previous solvent-borne coatings with higher VOC contents. VOC content is defined as the ratio of solvent to non-volatile solids. The water present in the aqueous composition does not enter into the calculation. The present composition has an ultra low VOC content of about 0.4 to about 2.0 pounds/gallon as compared to the EPA's VOC content standard of 4.8 pounds/gallon.
The coating compositions and systems of the present invention include a resin or an adhesion promoter. The class of preferred resin is a halogenated polyolefin, more preferably a CPO. In the coating compositions of the present invention a chlorinated polyolefin such as those commercially available by the trade names CP310W, CP347W or CP349W were found to be particularly useful.
CP310W, CP347W and CP349W can be obtained from Eastman Chemical Company (Kingsport, Tenn., U.S.A.).
The selection of the resin depends on many factors such as the surface to be coated, processing conditions, cost, the other components to be selected (the coalescing agent, anionic surfactant, etc.) and the environment. The final coating compositions of the present invention preferably employ the selected resin in the amount of about 5 to about 40 weight percent.
The coating compositions of the present invention further include a modified anionic polyurethane dispersion blend. Preferably, the modified anionic polyurethane dispersion blends include combinations of the newly developed CK Witco UCX99 (research code) and UCX00 (research code) series polyurethane blends with or without Witcobond™ W-240 (research code). In the coating compositions of the present invention, the modified anionic polyurethane dispersion blends are preferably the CK Witco UCX99 and UCX00 series identified by the research codes UCX99-027, UCX99-082, UCX99-079, UCX99-083and UCX00-002, which were found to be particularly useful.
CK Witco UCX99-027, UCX99-79, UCX99-082, UCX99-083, UCX00-002 and Witcobond™ W-240 blends can be obtained from CK Witco Corporation (Tarrytown, N.Y., U.S.A.).
The amount of modified anionic polyurethane dispersion blends in the present composition depends upon the VOC, dry film thickness, gloss and adhesion properties of the plastic coating. The final coating compositions of the present invention preferably employ the selected modified anionic polyurethane dispersion blends in the amount of about 30% to about 50% based on the total weight of the formulation.
The coating compositions of the present invention further include coalescing agents and surface tension reducer. In the coating combinations of the present invention the coales
Apollo Coating Technologies, Inc.
Griggs Dennis T.
Griggs Scott T.
Michl Paul R.
LandOfFree
One-pack waterborne adhesion coatings for thermoplastic olefins does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with One-pack waterborne adhesion coatings for thermoplastic olefins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and One-pack waterborne adhesion coatings for thermoplastic olefins will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2613875