Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-11-23
2001-06-26
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S261000, C524S265000, C524S269000
Reexamination Certificate
active
06251973
ABSTRACT:
TECHNICAL FIELD
This disclosure relates to novel coating compositions prepared from a reactive polymer, a hydrazide compound and a silane compound. The coating compositions, which can be formaldehyde-free and isocyanate-free, cure to provide an interpenetrating network (IPN) coating having excellent properties.
BACKGROUND OF RELATED ART
Paints can be considered as falling into two general categories, namely, water-based paints and solvent-based paints. Which category of paint is suitable for a given application depends on the conditions to be experienced by the paint. Conventional water-based paints have generally been considered inferior to solvent-based paints with respect to weather resistance, solvent resistance and adhesion. Recently, however, the use of solvent-based paints has become environmentally disfavored, with an emphasis being placed on achieving acceptable results with paints having a relatively low volatile organic content (“VOC”). Specifically, efforts have been made to provide paints or coating which are isocyanate-free and formaldehyde-free yet which exhibit acceptable physical characteristics.
It is therefore an object of the present invention to provide a coating composition which can be isocyanate-free and formaldehyde-free, yet exhibit good adhesion, durability, chemical resistance, water resistance and print resistance. This desired combination of properties has now been achieved by the novel coating compositions described herein.
SUMMARY
The novel coating compositions described herein include a polymer and a silane. The polymer has at least one reactive functional group and a hydrazide group. The silane can be selected from the group consisting of silanes and polysilanes. Optionally, the coating composition includes a pigment. Coatings made from such compositions are also described. Methods of preparing a coating by applying the coating composition to a substrate and curing to form a film are also described herein.
The preferred coating compositions in accordance with this disclosure are formaldehyde-free and isocyanate-free, can be air cured and provide coatings that exhibit improved adhesion to the substrate, improved print and block resistance and improved solvent and water resistance.
DESCRIPTION OF PREFERRED EMBODIMENTS
The novel coating compositions in accordance with this disclosure include: (a) a polymer having at least one reactive functional group, the polymer also having a hydrazide group attached thereto; and (b) a silane.
Polymers useful in forming the coating compositions include, for example, acrylic polymers, modified acrylic polymers, polyepoxides, polyesters, polycarbonates, polyurethanes, polyamides, polyimides, polysiloxanes, polycarbamates and mixtures thereof. The molecular weight of the polymer is not critical. The polymer will generally have a molecular weight of 2,000 to 2,000,000 and preferably from 100,000 to 1,000,000.
The polymer includes reactive functional groups. The functional groups can provide a site for attachment of the hydrazide-containing compound and also can provide a site for cross-linking by the silane compound as described in detail below. Suitable reactive functional groups include, for example, carboxyl, hydroxyl, epoxy, amino alkylamino, multi-functional amine, amido and keto groups or combinations thereof. The degree of substitution of the reactive functional groups is not critical, but rather can be adjusted to provide a coating having desired characteristics. Thus, for example, where carboxyl groups are present on the polymer, acid numbers as low as about 20 should provide adequate cross-linking to form a coating. However, if a coating which can withstand 200 MEK rubs is desired, an acid number in the range of about 40 to about 80 should be used. The polymer may be self-crosslinking or U.V. curable. It is within the purview of one skilled in the art to prepare suitable polymers containing reactive functional groups. Suitable polymers are commercially available from a variety of suppliers.
Where acrylic polymers are utilized, such polymers can be prepared from monomers such as acrylic acid and methacrylic acid, alkyl and cycloalkyl acrylates and methacrylates having 1 to 18, preferably 4 to 13, carbon atoms in the alkyl or cycloalkyl moiety, or mixtures of such monomers. Examples of these include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, cyclohexyl methacrylate, and 2-ethylhexyl methacrylate.
The reactive functionality on the acrylic polymer may be incorporated by reacting functional monomers having carboxyl, hydroxyl, epoxy, amino, and alkylamino functional groups. Carboxyl containing monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-acryloxymethoxy-O-phthalic acid, 2-acryloxy-1-methylethoxy-O-hexahydrophthalic acid. Hydroxy functional monomers include 2-hydroxylethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy butyl acrylate, hydroxybutyl methacrylate, allyl alcohol, and methallyl alcohol. Epoxy functional monomers include glycidyl methacrylate. Examples of alkylamino acrylates and methacrylates include aminomethyl, aminopropyl, aminobutyl and aminohexyl acrylates and methacrylates, dimethylaminoethyl acrylate, and dimethylaminoethyl methacrylate. Other suitable monomers include N-alkoxymethylacrylamide, and N-(butoxymethyl)acrylamide. Other ethylenically unsaturated monomers such as vinyl, styrene, &agr;-methyl styrene, vinyl toluene, t-butyl styrene may also be included to provide the desired physical characteristics. Particularly useful polymers are carboxylated styrene acrylate polymers.
Modified acrylics can also be used as the acrylic polymer. Examples of these include polyester-modified acrylics or polyurethane-modified acrylics, as are well known in the art. An example of one preferred polyester-modified acrylic is an acrylic polymer modified with &dgr;-caprolactone. Such a polyester modified acrylic is described in U.S. Pat. No. 4,546,046 to Etxell et al. Polyurethane modified acrylics are well known in the art. An example is set forth in U.S. Pat. No. 4,584,354, the disclosure of which is hereby incorporated by reference.
Polyesters having hydroxyl groups, acid groups, or amino groups as reactive functional groups can also be used as the polymer in the present compositions. Such polyesters are well-known in the art, and may be prepared by the polyesterification of organic polycarboxylic acids (e.g., phthalic acid, hexahydrophthalic acid, adipic acid, maleic acid) or their anhydrides with organic polyols containing primary or secondary hydroxyl groups.
Polyurethanes useful as the polymer in the present compositions can be prepared by reacting polyisocyanate and polyol with an OH:NCO equivalent ratio of greater than 1:1, to obtain polyurethanese with terminal hydroxyl functionality. In this case capping of the isocyanate occurs simultaneously with the synthesis of the polyurethane resin. Alternatively, polyurethane may be formed by reacting polyisocyanate and polyol with an OH:NCO ratio of less than 1:1. In this case, where excess isocyanate is used, the polyurethane having unreacted isocyanate functionality is then reacted with a capping agent. Suitable capping agents include reactive alcohols or amines. Examples of these are trimethylolpropane, ethanolamine, diethanolamine, Solketal, diols, triols, or a mixture of diols and triols. Preferably, any unreacted isocyanate is removed before using the polyurethane as the polymer.
Suitable carbamate functional polymers can be prepared from an acrylic monomer having a carbamate functionality in the ester portion of the monomer. Such monomers are well-known in the art and are described, for example in U.S. Pat. Nos. 3,479,328; 3,674,838; 4,126,747; 4,279,833; and 4,340,497, the disclosures of which are incorporated herein by reference. One method of synthesis involves reaction of a hydroxy ester with urea to form the carbamyloxy carboxylate (i.e., carb
Robinson Gregory Frantz
Shemancik Robin Carol
Speight Robert Dale
Wong Philip Titsum
Akzo Nobel N.V.
Dawson Robert
Deluca Peter
Parker Lainie E.
Robertson Jeffrey B.
LandOfFree
Coatings and coating compositions of a reactive... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coatings and coating compositions of a reactive..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coatings and coating compositions of a reactive... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441215