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
2002-02-01
2004-01-13
Lipman, Bernard (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...
C524S521000
Reexamination Certificate
active
06677398
ABSTRACT:
This invention relates to an aqueous ink binder composition, particularly to an aqueous ink binder including (a) 30-60%, by weight based on the dry weight of the binder composition, of a first polymer including, as polymerized units, 15-75%, by weight based on the weight of the first polymer, ethylenically unsaurated carboxylic acid monomer having a pKa from 2.0 to 4.6, the first polymer having a calculated Hansch parameter from 1.3 to 2.1, and (b) 70-40%, by weight based on the dry weight of the binder composition, of a second polymer, the second polymer being an aqueous emulsion polymer. Also the invention relates to an aqueous ink composition including the ink binder and a method for providing an aqueous ink having press resolubility and, as a dry ink film, water resistance.
“Aqueous ink compositions” herein include both pigmented inks and unpigmented inks, such as are known in the art as overprint varnishes. Aqueous ink compositions including a soluble resin and an emulsion polymer and the formation of such compositions by blending and by various two-stage polymerization strategies have been disclosed. Such compositions have been posited to offer beneficial ink properties such as rheology. However, the inks formed therefrom have either exhibited unacceptable resolubility on the press or poor water resistance as the dried ink film. When the resolubility of the ink on the press is unacceptable a brief press stoppage permits the ink to dry to an extent that the ink does not redissolve in fresh ink on restarting the press, thereby causing the transfer of dry ink particles to press surfaces and ultimately to the finished printed substrate surface. On the other hand it is desirable that the dried ink film exhibits water resistance so that the finished printed substrate surface is unaffected by contact with water.
U.S. Pat. No. 5,284,894 discloses resin-fortified latex polymers for low-foaming printing inks including a dispersed acrylic polymer, a polyelectrolyte resin, and a nonionic emulsifier.
However, improved aqueous ink binder compositions are still desired in order to provide aqueous inks having both press resolubility and, as the dry ink film, water resistance.
It has now been found that certain ink binder compositions formed from a certain first polymer and an emulsion polymer exhibit the desired performance in that inks formed therefrom exhibit press resolubility and the dry ink films of those inks exhibit water resistance.
In a first aspect of the present invention there is provided an aqueous ink binder comprising (a) 30-60%, by weight based on the dry weight of said binder composition, of a first polymer comprising, as polymerized units, 15-75%, by weight based on the weight of said first polymer, ethylenically unsaturated carboxylic acid monomer having a pKa from 2.0 to 4.6, said first polymer having a calculated Hansch parameter from 1.3 to 2.1, and
(b) 70-40%, by weight based on the dry weight of said binder composition, of a second polymer, said second polymer being an aqueous emulsion polymer.
In a second aspect of the present invention there is provided an aqueous ink comprising an aqueous ink binder and, optionally, a pigment, said ink comprising
(a) a first polymer comprising, as polymerized units, 15-75%, by weight based on the weight of said first polymer, ethylenically unsaturated carboxylic acid monomer having a pKa from 2.0 to 4.6, said first polymer having a calculated Hansch parameter from 1.3 to 2.1, and (b) a second polymer, said second polymer being an aqueous emulsion polymer; wherein the weight ratio of said first plymer to said second polymer on a solids basis is from 0.43:1 to 1.5:1.
In a third aspect of the present invention there is provided method for providing an aqueous ink which has press resolubility and, as a dry film, water resistance comprising
(a) forming an aqueous ink comprising an aqueous ink binder and, optionally, a pigment, said ink comprising (i) a first polymer comprising, as polymerized units, 15-75%, by weight based on the weight of said first polymer, ethylenically unsaturated carboxylic acid monomer having a pKa from 2.0 to 4.6, said first polymer having a calculated Hansch parameter from 1.3 to 2.1, and (ii) a second polymer, said second polymer being an aqueous emulsion polymer;
wherein the weight ratio of said first polymer to said second polymer on a solids basis is from 0.43:1 to 1.5:1; (b) applying said ink to a substrate with a press; and (c) drying, or allowing to dry, said applied ink.
The aqueous ink binder of the present invention includes 30-60%, preferably 35-60%, by weight based on the dry weight of the binder composition, of a first polymer including, as polymerized units, 15-75%, preferably 20-40%, by weight based on the weight of the first polymer, ethylenically unsaturated carboxylic acid monomer having a pKa from 2.0 to 4.6, preferably from 2.5 to 4.5, more preferably from 3.0 to 4.4, the first polymer having a calculated Hansch parameter from 1.3 to 2.1, preferably. By “aqueous” herein is meant that the medium in which the binder components are dissolved or dispersed is predominantly water. The first polymer includes, as polymerized units, 15-75%, by weight based on the weight of the first polymer, at least one ethylenically unsaurated carboxylic acid monomer having a pKa between 2.0 and 4.6. The pKa of monomers are known in the art and may be found, for example, in Lange's Handbook (15
th
Edition). The preferred carboxylic acid monomer is acrylic acid.
The first polymer further includes, as copolymerized unit(s), at least one monoethylenically-unsaturated monomer in addition to the carboxylic acid-functional monomer such as, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, aminoalkyl (meth)acrylate, N-alkyl aminoalkyl (methacrylate), N,N-dialkyl aminoalkyl (meth)acrylate; urieido (meth)acrylate; (meth)acrylonitrile and (meth)acrylamide; styrene, &agr;-methylstyrene, or other alkyl-substituted styrenes; butadiene; vinyl acetate, vinyl propionate, or other vinyl esters; vinyl monomers such as vinyl chloride, vinylidene chloride, and N-vinyl pyrrolidone. The use of the term “(meth)” followed by another term such as acrylate, acrylonitrile, or acrylamide, as used throughout the disclosure, refers to both acrylate and methacrylate, acrylonitrile and methacrylonitrile, or acrylamide and methacrylamide, respectively. Preferred monoethylenically-unsaturated monomers in addition to the carboxylic acid-functional monomer are styrene, &agr;-methylstyrene, and combinations thereof.
The first polymer composition is selected so as to provide a calculated Hansch parameter from 1.3 to 2.1. In the event that more than one first polymer is present in the ink binder composition, a weight-averaged Hansch parameter is used. The Hansch parameter for a polymer is calculated using a group contribution method. The monomer units forming a polymer are assigned a hydrophobicity contribution and the hydrophobicity of the polymer, the Hansch parameter, is calculated based on the weight average of the monomers in the polymer as disclosed in Hansch and Fujita, J. Amer. Chem. Soc., 86, 1616-1626 (1964); H. Kubinyi, Methods and Principles of Medicinal Chemistry, Volume 1, R. Mannhold et al., Eds., VCH, Weinheim (1993); C. Hansch and A. Leo, Substituent Constants for Correlation Analysis in Chemistry and Biology, Wiley, New York (1979); and C. Hansch, P. Maloney, T. Fujita, and R. Muir, Nature, 194. 178-180 (1962). High pH Hansch parameters are used.
Values of the hydrophobicity contributions for several monomers are:
Monomer
Hydrophobicity Contribution
ethyl acrylate
2.11
butyl acrylate
3.19
2-ethyl hexylacrylate
5.22
styrene
4.29
&agr;-methylstyrene
4.7
methyl methacrylate
1.89
ethyl methacrylate
2.43
butyl methacrylate
3.51
isobornyl methacrylate
2.22
acrylic acid
−2.52
itaconic acid
−3.34
methacrylic acid
−2.2
maleic anhydride
&
Egolf Scott Lind
Finch William Christopher
Mailloux Aaron Thomas
Sheng Miao-Hsun Li
Walker Stephen Lee
Bakule Ronald D.
Lipman Bernard
Rohm and Haas Company
LandOfFree
Aqueous ink binder composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aqueous ink binder composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous ink binder composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3240891