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
2000-05-12
2002-03-12
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...
C523S201000
Reexamination Certificate
active
06355720
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to non-yellowing latex formulations and more particularly relates to latex formulations which exhibit a reduced amount of yellowing when exposed to heat, aldehydes or ultraviolet light.
BACKGROUND OF THE INVENTION
Polymers prepared by emulsion polymerization are used in a wide variety of applications. For example, latex formulations prepared by emulsion polymerization are used in paints, polishes, finishes, films, inks, clear coats, stains, varnishes, overprint varnishes, and powder coatings.
It has long been known that latex formulations are prone to substantial yellowing when exposed to heat, aldehydes or light, especially ultraviolet light. Bluing agents may be added to yellowed polymers in one approach that has long been used in polymer chemistry. However, this approach is remedial in nature and does not adequately address the source of the problem.
The yellowing of latex formulations is particularly problematic in clear coat formulations, especially when the formulation is to be used over lightly colored substrates such as white and cream-colored substrates. Additionally, yellowing of latex formulations has been problematic when such formulations are exposed to various aldehydes such as formaldehyde and benzaldehyde.
Therefore, a need exists for clear coat formulations which reduce or eliminate the amount of yellowing which is exhibited when such formulations are exposed to heat, aldehydes and ultraviolet light.
SUMMARY OF THE INVENTION
The present invention provides coating compositions which exhibit a reduced amount of yellowing when exposed to heat, aldehydes or ultraviolet light.
One aspect of the invention provides a latex formulation that exhibits reduced yellowing. The formulation includes a polymeric particle which includes a seed latex polymer that incorporates at least one monomer such as a vinyl aromatic monomer, an alkyl acrylate, an alkyl methacrylate, or combinations of these monomers. The polymeric particle also includes an inner polymer layer overlying at least a portion of the seed latex polymer. The inner polymer layer incorporates monomers including: an acetoacetoxy-containing monomer such as an acetoacetoxyalkyl acrylate, an acetoacetoxyalkyl methacrylate, or combinations of these monomers; an ethylenically unsaturated ester-containing monomer such as an alkyl acrylate, an alkyl methacrylate, or combinations of these monomers; and an ethylenically unsaturated monomer such as a vinyl aromatic monomer, an acrylic acid monomer, a methacrylic acid monomer, or combinations of these monomers. The polymeric particle additionally includes an outer polymer layer that includes less than about 5 percent, more preferably less than about 1 percent, by weight of total incorporated vinyl aromatic monomers and includes at least one incorporated monomer such as an alkyl acrylate monomer, an alkyl methacrylate monomer, and combinations of these monomers. The inner polymer layer is positioned between at least a portion of the seed latex polymer and the outer polymer layer and the polymeric particle exhibits reduced yellowing upon exposure to ultraviolet light.
In preferred latex formulations, the polymeric particle further includes at least one interstitial layer positioned between the inner polymer layer and the outer polymer layer. The interstitial polymer layer incorporates monomers including: an acetoacetoxy-containing monomer such as acetoacetoxyalkyl methacrylates, acetoacetoxyalkyl acrylates, and combinations of these monomers; an ethylenically unsaturated-ester containing monomer such as an alkyl acrylate, an alkyl methacrylate, and combinations of these monomers; and a diethylenically unsaturated monomer having the formula
CH
2
═C(R
1
)—C(═O)—O—CH
2
—[CH
2
]
n
—CH
2
—O—C(═O)—C(R
2
)═CH
2
where R
1
and R
2
are independently either H or an alkyl group having from 1 to 5 carbon atoms and n is an integer ranging from 0 to 12. Preferred diethylenically unsaturated monomers include 1,10, decanediol diacrylate, 1,9-nonanediol diacrylate, 1,8-octanediol diacrylate, 1,7-heptanediol diacrylate, 1,6-hexanediol diacrylate, 1,5-pentanediol diacrylate, 1,4-butanediol diacrylate, 1,3-pentanedioldiacrylate, 1,2-ethanediol diacrylate, and combinations of these monomers. An especially preferred diethylenically unsaturated monomer incorporated in the interstitial polymer layer is 1,6-hexanediol diacrylate.
In other preferred latex formulations, the monomer incorporated in the outer polymer layer of the polymeric particle includes methyl methacrylate, 2-ethylhexyl acrylate, or combinations of these monomers.
Preferred latex formulations include a polyfunctional amine having at least two amine groups. In more preferred latex formulations, one of the amine groups on the polyfunctional amine is bonded to a first carbon atom and a second amine group is bonded to a second carbon atom and 3 or less or 6 or more carbon atoms separate the first carbon atom from the second carbon atom. Preferred polyfunctional amines include 1,2-diaminopropane, 1,3-diaminobutane, 1,2-diaminobutane, 1,3-diaminopentane, 1,4-diaminopentane, 4-methyl-1,3-diaminopentane, 2-methyl-1,3-diaminopentane, 2-methyl-1,4-diaminopentane, 3-methyl-1,4-diaminopentane, 2,4-diaminopentane, 2,5-diaminohexane, 2,4-diaminohexane, 1,3-diaminohexane, 1,4-diaminohexane, 1,5-diaminohexane, 5-methyl-1,3-diaminohexane, 4-methyl-1,3-diaminohexane, 3-methyl-1,3-diaminohexane, 2-methyl-1,4-diaminohexane, 3-methyl-1,4-diaminohexane, 5-methyl-1,4-diaminohexane, 2-methyl-1,5-diaminohexane, 3-methyl-1,5-diaminohexane, 4-methyl-1,5-diaminohexane, 1,3-diaminoheptane, 1,4-diaminoheptane, 1,5-diaminoheptane, 1,3-diaminooctane, 1,4-diaminooctane, 1,5-diaminooctane, and combinations of these. An especially preferred polyfunctional amine for inclusion in a latex formulation is 1,3-diaminopentane.
Still other preferred latex formulations of the present invention include reducing agents. A particularly preferred reducing agent is the metabisulfite anion which may be present as the sodium, potassium, lithium, ammonium, or other salt. Other more preferred latex formulations include a base such as ammonia, ammonium hydroxide, alkylamines, dialkylamines, trialkylamines, or combinations of these bases. Especially preferred bases for inclusion in latex formulations include ammonia, ammonium hydroxide, or combinations of these bases.
Another aspect of the invention provides a latex formulation that 5 exhibits reduced yellowing that includes a base, a polyfunctional amine having at least two amine groups, and a polymeric particle. One of the two amine groups of the polyfunctional amine is bonded to a first carbon atom and a second amine group is bonded to a second carbon atom and 3 or less or 6 or more carbon atoms separate the first carbon atom from the second carbon atom. The polymeric particle of the latex formulation includes a seed latex polymer that incorporates at least one monomer such as a vinyl aromatic monomer, an alkyl acrylate, an alkyl methacrylate, or combinations of these monomers. The polymeric particle also includes an inner polymer layer overlying at least a portion of the seed latex polymer. The inner polymer layer incorporates monomers including: an acetoacetoxy-containing monomer such as an acetoacetoxyalkyl acrylate, an acetoacetoxyalkyl methacrylate, or combinations of these monomers; an ethylenically unsaturated ester-containing monomer such as an alkyl acrylate, an alkyl methacrylate, or combinations of these monomers; and an ethylenically unsaturated monomer such as a vinyl aromatic monomer, an acrylic acid monomer, a methacrylic acid monomer, or combinations of these monomers. The polymeric particle additionally includes an outer polymer layer including at least one incorporated alkyl acrylate, alkyl methacrylate, or a combination of these monomers. The inner polymer layer is positioned between at least a portion of the seed latex polymer and the outer polymer layer and the latex formulation exhibits reduced yellowing upon exposure to heat.
In a preferr
Canard Gregory M.
Taylor James W.
Trumbo David L.
Bovee Warren R.
Hamilton Neil E.
Johnson Polymer, Inc.
Michl Paul R.
Rymarz Renee J.
LandOfFree
Latex formulations with reduced yellowing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Latex formulations with reduced yellowing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Latex formulations with reduced yellowing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2876345