Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-12-06
2003-04-01
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S157000, C525S192000, C525S218000, C525S329900, C525S330500, C525S504000, C525S509000, C525S512000, C526S328000
Reexamination Certificate
active
06541577
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to carbamate functional polymers and/or oligomers, and curable coating compositions containing the same. The curable coating compositions of the invention are particularly useful in composite color-plus-clear coating systems.
BACKGROUND OF THE INVENTION
Curable coating compositions such as thermoset coatings are widely used in the coatings art. They are often used as topcoats in the automotive and industrial coatings industry. Color-plus-clear composite coatings are particularly useful as topcoats where exceptional gloss, depth of color, distinctness of image, or special metallic effects are desired. The automotive industry has made extensive use of these coatings for automotive body panels. Color-plus-clear composite coatings, however, require an extremely high degree of clarity in the clearcoat to achieve the desired visual effect. High-gloss coatings also require a low degree of visual aberations at the surface of the coating in order to achieve the desired visual effect such as high distinctness of image (DOI).
As such, these coatings are especially susceptible to a phenomenon known as environmental etch. Environmental etch manifests itself as spots or marks on or in the finish of the coating that often cannot be rubbed out.
It is often difficult to predict the degree of resistance to environmental etch that a high gloss or color-plus-clear composite coating will exhibit. Many coating compositions known for their durability and/or weatherability when used in exterior paints, such as high solids enamels, do not provide the desired level of resistance to environmental etch when used in high gloss coatings such as the clearcoat of a color-plus-clear composite coating.
Many compositions have been proposed for use as the clearcoat of a color-plus-clear composite coating, such as polyurethanes, acid-epoxy systems and the like. However, many prior art systems suffer from disadvantages such as coatability problems, compatibility problems with the pigmented basecoat, solubility problems. Moreover, very few one-pack coating compositions have been found that provide satisfactory resistance to environmental etch, especially in the demanding environment of automotive coatings.
It has been found that carbamate functional polymers such as those described in U.S. Pat. No. 5,356,669 can be used to provide coating compositions which exhibit significantly improved environmental etch resistance. Carbamate functional polymers have been used to provide commercially advantageous coatings compositions, especially as clearcoats in composite color-plus-clear coatings.
However, although coating compositions containing carbamate functional polymers generally provide the performance properties currently required by the automotive industry, continuous improvement is always desired. In particular, it would be advantageous to increase the percent nonvolatile solids (%NV) of curable coating compositions containing carbamate functional polymers. Increasing the %NV of a coating composition provides a competitive advantage with respect to environmental concerns, air permiting requirements and cost. Curable coating compositions having ever increasing %NVs are greatly desired by the automotive manufacturing industry. However, neither sprayability nor applied appearance may be affected by decreases in the volatile organic content (VOC). At the same time, such improvements must be achieved without any decrease in environmental etch resistance or other commercially required performance property.
Accordingly, it is an object of the instant invention to provide curable coating compositions which provide all of the advantages of prior art carbamate containing coating compositions, especially good environmental etch resistance, but further exhibit increased %NV (nonvolatile) or decreased VOC (volatile organic content) at a sprayable viscosity and desireable applied appearance.
SUMMARY OF THE INVENTION
It has unexpectedly been found that these and other objects of the invention can be achieved with the use of a particular carbamate functional polymer which is the polymerization reaction product of (a) a polymer or oligomer comprising a plurality of functional groups reactive with an active hydrogen group, and (b) a monomeric compound of the formula:
wherein at least one of Y and Z is an active hydrogen containing group and the other is a primary carbamate group, and R is of the formula: —(L)
n
—R′ wherein L is a linking group of one or more carbons containing heteratoms selected from the group consisting of O, N, and mixtures thereof, R′ is an alkyl group free of heteratoms and selected from the group consisting of branched alkyl groups having from 5 to 30 carbons, straight chain alkyl groups of more than 2 carbons, and mixtures thereof, and n is a number from 0 to 1.
The invention further provides curable coating compositions which comprise the particular carbamate functional resins of the instant invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The advantages of the instant invention derive from the use of a particular carbamate functional polymer or oligomer.
For the purposes of the instant invention, the term “polymer” refers to compounds having number average molecular weights in the range of from 1500 to over 1,00,000 Daltons, while “oligomer” refers to compounds having number average molecular weights in the range of from 200 to 1499 Daltons. The terms “polymeric compound” and “polymeric compounds” as used herein are meant to encompass both “polymer” and “oligomer” as defined above. Moreover, the term “polymeric compounds” as used herein may be used in regards to the particularly claimed carbamate functional polymers and oligomers of the instant invention as well as to the polymer or oligomer (a) used as a reactant in the polymerization reaction which produces the particular carbamate functional polymers or oligomers of the invention.
The carbamate functional polymeric compounds of the invention are the reaction product of a polymer or oligomer (a) which comprises a plurality of functional groups reactive with an active hydrogen group, and a monomeric compound (b) of the formula:
wherein Y and Z are selected from the group consisting of all active hydrogen containing group and a primary carbamate group, and may not be the same; R is of the formula: —(L)
n
—R′ wherein L is a linking group of one or more carbons containing heteratoms selected from the group consisting of O, N, and mixtures thereof; R′ is an alkyl group free of heteratoms and selected from the group consisting of branched alkyl groups having is 5 to 30 carbons, straight chain alkyl groups of more than 2 carbons, and mixtures thereof; and n is a number from 0 to 1.
The polymeric compound (a) may generally be any compound of the appropriate molecular weight which has a plurality of the appropriate functional groups (i) discussed below. When the carbamate functional polymeric compound is an oligomer, it will generally have a number average molecular weight in the range of from 200 to 1499 Daltons. When the carbamate functional polymeric compound of the invention is a polymer, it will have a number average molecular weight in the range of 1500 Daltons to over 1,000,000 Daltons, preferably between 1500 and 50,000 Daltons, most preferably between 1500 and 15,000 Daltons.
Polymeric compound (a) may be acrylic, modified acrylic, polyurethane, polyester, polyurea, alkyd, polysiloxane, polyethers, epoxy upgrades, mixtures thereof, and the like. Preferably, the polymeric compound (a) will be polyurethane, polyester, acrylics, or the like. Most preferably, the polymeric compound (a) will be polyurethane, especially an isocyanate functional polyurethane polymer or urethane oligomer.
Suitable polymeric compounds (a) must comprise a plurality of functional groups (i) which are reactive with an active hydrogen group. “Active hydrogen group” as used herein refers to functional groups which donate a hydrogen group during the reaction with the functional groups of compounds (a). Examp
Ohrbom Walter H
Rehfuss John W.
Asinovsky Olga
BASF Corporation
Golota Mary E.
Seidleck James J.
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