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
2002-09-12
2004-11-30
Mulcahy, Peter D. (Department: 1713)
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...
C524S318000, C508S181000, C427S358000
Reexamination Certificate
active
06825258
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to non-flatting and slip-enhancing coating additives, powder coating compositions containing the additives, and to a process for coating a substrate using the powder coating composition.
2. Description of Related Art
Slip is the relative movement between two objects that are in contact with each other. If an object is moved along a surface, there is a resistance acting in a direction opposite the movement. The resisting force is also called frictional force, friction resulting from the unevenness of the two surfaces in contact.
Coating systems, including powder coatings are susceptible to damage when in contact with solid objects. Paint films, for instance, can be easily damaged during drying, when they have not yet cured. In the case of baking enamels, damage can occur when the films have not yet cooled. In addition, scratches, which are discontinuities on surfaces, can cause attachment of air-borne contaminants and corrosive agents leading eventually to corrosion problems. Powder coating systems are well known to those skilled in the art. A common problem with many powder coatings is that they are subject to mar or scratching.
Slip additives provide some degree of protection against such damages. For example, in automotive coating applications, they protect the not fully hardened freshly applied enamels, and in can coatings, they protect the coating during filling and distribution.
The concepts of slip and mar (or scratch) resistance are very closely interrelated in that the same additive may perform both functions—impart slip and provide scratch resistance; in addition the principle underlying both is the same. A hard object touching a paint film containing an additive can be deflected due to the surface lubricity of the additive. This results in a greater apparent film hardness or scratch resistance.
A slip additive should generally fulfill several requirements. The additive should migrate to the film surface during the drying process, forming a film which not only adheres to the coating, but also favorably influences its flow and leveling properties. In addition, this film should have lubricating qualities, expressed as the ability to carry a load in a very thin layer.
Compounds based on silicone chemistry have been used as mar and slip additives for about 30 years. Examples of silicone-based slip additives include polydimethylsiloxanes, polyoxyalkylenesiloxane (polysiloxane/polyether) copolymers, and polyoxyalkylene methylalkylsiloxane copolymers.
The problem with many slip additives is that they reduce the gloss of the cured coating. The present invention provides enhanced slip (reduction of coefficient of friction) to cured powder coatings useful in rendering the cured coatings more resistant to mar or scratch without an appreciable loss in gloss.
A detailed description describing the concept of slip and mar and the developments of additives to improve scratch resistance and impart slip can be found in an article by F. Fink, et al., entitled “Development of New Additives to Improve Scratch Resistance and Impart Slip To Solvent-Based Coating Systems” in
Journal of Coatings Technology
, Vol. 62, No. 791, December 1990.
U.S. Pat. No. 3,455,726, Mitchell, Jr. et al., Jul. 15, 1969, discloses an article comprising a paper substrate, a moisture resistant film of polymer, selected from the group consisting of vinylidene chloride polymers, polyethylene and polypropylene superimposed on said substrate, and a slip coating on said film, said slip coating consisting essentially of a partial ester of a fatty acid and hexitol anhydride, including a polyoxyethylene derivative of said ester.
U.S. Pat. No. 4,289,828, Ota et al., Sep. 15, 1981, discloses a magnetic recording medium made by coating a base with a magnetic coating materials which is a dispersion of magnetic particles in a binder of synthetic resins using a polyfunctional aromatic isocyanate as a curing agent, characterized by the addition of a sorbitan stearate type surface active agent.
Japanese Laid-open Patent Publication No. 57-30119, Nishimatsu, Feb. 18, 1982, discloses a magnetic recording medium, comprising a magnetic paint containing a curing component and a surfactant and applied on a substrate, wherein said curing component contains isophorone diisocyanate, and said surfactant contains a saturated fatty acid ester of sorbitan.
Japanese Patent Publication No. 63-44023, Suzuki et al., Sep. 2, 1988 discloses a method of forming an coated layer of low frictional resistance on the surface of an article such as a slip joint of a safety belt connected to a car seat, said method comprising immersing the article to be coated in a fluidized bed containing 100 parts weight of polyamide powder and 0.01-5 parts by weight of PTFE powder, and thereby applying the mixed powders as a low-friction coating on the surface of the particle.
SUMMARY OF THE INVENTION
The present invention relates to a composition, comprising: (a) at least one non-crosslinked product made by the reaction of an alcohol and a carboxylic acid or a reactive equivalent of said carboxylic acid; said product comprising at least one ester functionality and at least one straight chain hydrocarbyl group of about 10 to about 100 carbon atoms; and (ii) at least one fluoropolymer. The invention also relates to a powder coating composition comprising a film forming resin and a non-flatting slip-enhancing amount of an additive composition comprising the foregoing combination of (a) and (b), and to a method for a coating a substrate using the foregoing powder coating composition.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:
(1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form an alicyclic radical);
(2) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
(3) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.
A straight-chain hydrocarbyl group is a hydrocarbyl group that is free from branching and ring structures. However, such a hydrocarbyl group can still have a hetero substituent that does not alter the predominantly hydrocarbon character of the hydrocarbyl group. Examples of straight chain hydrocarbyl groups include n-butyl, n-octyl, n-dedodecyl and n-octadecyl groups.
The phrase “reactive equivalent” of a material means any compound or chemical composition other than the material itself which reacts or behaves like the material itself under the reaction conditions. Thus reactive equivalents of a carboxylic acid will include acid-producing derivatives such as an anhydride, an acyl halide, and mixtures thereof unless specifically stated otherwise.
The Alcohol (a)
Alcohols suitable for this invention i
Laferty Samuel B.
Mulcahy Peter D.
Shold David M.
The Lubrizol Corporation
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