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...
Patent
1996-01-04
1998-11-17
Mulcahy, Peter D.
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...
524822, C08J 524
Patent
active
058377620
DESCRIPTION:
BRIEF SUMMARY
The present invention refers to polymer latex compositions, more particularly, to polymer latex compositions prepared with a sulfur-free and halogen-free chain transfer agent useful in paper coating applications.
Polymer latices useful in paper coating applications need to provide good dry and wet pick strength properties. It is well-known that sulfur- and halogen-containing chain transfer agents provide polymer latices with molecular weights suitable to exhibit high strength. Halogenated chain transfer agents have been extensively used in the past, however less and less in the recent years due to environmental concerns. On the other hand, sulfur-containing chain transfer agents, under certain extreme application conditions, can lead to undesirable odor contribution in the coated paper.
In view of the outlined deficiencies, there is still a need for polymer latex compositions which are prepared with sulfur-free and halogen-free chain transfer agents, whose binding properties, that is, wet and dry pick strength properties, remain comparable to a polymer latex composition prepared with sulfur-containing and/or halogen-containing chain transfer agents.
Accordingly, in one aspect, the present invention is a polymer latex composition having a glass transition temperature between -10.degree. C. and 70.degree. C. prepared with a sulfur- and halogen-free chain transfer agent comprising, in polymerized form, (A) from 10 weight percent to 80 weight percent of monovinylidene aromatic monomer(s); (B) from 0 weight percent to 65 weight percent of conjugated diene monomer(s); (C) from 0 weight percent to 70 weight percent of acrylate monomer(s); and (D) the remaining amount of other polymerizable comonomer(s); with the proviso that the combined weight percentage of components (B) and (C) is greater than zero and wherein the sulfur- and halogen-free chain transfer agent is an abietic acid-containing rosin.
Surprisingly, it has been found that the polymer latex compositions of the present invention which are prepared by using an abietic acid-containing rosin as a chain transfer agent give, under certain extreme application conditions, less odor than latex compositions prepared with the usual sulfur-based chain transfer agents, while exhibiting unexpectedly good binding properties, such as high wet and dry binding strength despite high gel content, and a balanced application profile of paper gloss, ink gloss and ink set-off properties.
Latices useful in the practice of the present invention include latices prepared with sulfur- and halogen-free chain transfer agents comprising an aqueous dispersion having dispersed therein a polymeric phase, comprising, in polymerized form, monovinylidene aromatic monomer(s), conjugated diene monomer(s) and/or acrylate monomer(s). Typically, these latices have glass transition temperatures (Tg) of less than 70.degree. C., preferably less than 40.degree. C., and most preferably less than 35.degree. C. but not less than -10.degree. C., as measured using a differential scanning calorimeter. Optionally, these latices can contain other polymerizable comonomers, such as ethylenically unsaturated carboxylic acid monomers, nitrile monomers, vinyl ester monomers, hydroxyalkyl-(meth)acrylate monomers, alkoxyalkyl(meth)acrylate monomers and (meth)acrylamide monomers.
The sulfur- and halogen-free chain transfer agents useful in the present invention are the so-called rosins. Typically, there are three types of rosins: (a) gum rosin which is obtained from oleo resin exuded from the wound of living pine trees and distillation of volatile turpentine; (b) wood rosin obtained by solvent extraction of pine stump wood along with removal of the turpentine by steam distillation; and (c) tall oil rosin obtained by the separation of tall oil using the sulphate or Kraft process. The main components of gum rosin are a number of isomeric rosin acids, such as monocarboxylic acids of the alkyl hydrophenanthrene type (abietic acid type) having a molecular formula C.sub.20 H.sub.30 O.sub.2.
The preferred rosins for use
REFERENCES:
patent: 4148770 (1979-04-01), Stahle et al.
patent: 4478974 (1984-10-01), Lee et al.
patent: 4968740 (1990-11-01), Makati et al.
patent: 5008329 (1991-04-01), Abe et al.
patent: 5137977 (1992-08-01), Saitoh et al.
patent: 5194539 (1993-03-01), Charmot et al.
Elsaesser Dominik Martin
Salminen Pekka Johannes
Stollmaier Friederike Theresia
Mulcahy Peter D.
The Dow Chemical Company
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