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
2002-11-19
2004-09-28
Pezzuto, Helen L. (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...
C524S558000, C524S559000, C526S303100, C526S320000, C526S321000, C526S328500
Reexamination Certificate
active
06797768
ABSTRACT:
This invention relates to pourable liquid compositions which are radiation curable comprising an ethylenically unsaturated polymer having radiation polymerisable functionality dissolved in a monomer, the compositions being water swellable upon radiation curing.
Many types of water absorbent or water swellable polymers are known (J. Macromol. Sci. Rev. Macromol. Chem. Phys. C34(4) 1994 pp 607-662).
Commercial ‘superabsorbent polymers’ are available and they have the ability to absorb water or aqueous salt solutions, often in an amount several times their own weight. They are commonly supplied as powders, or as fibres or films. The most common form is powders which are usually incompressible and infusible and so are not ideally suited to application as a direct coating.
Films or fibres may also be prepared in-situ via common coating or spinning techniques which usually involve polymerising hydrophilic monomers in solvents such as water. Similarly they can be applied as coatings to fabrics or other articles by many of the usual water or solvent based coating techniques.
When such coatings or films are prepared insitu, thermal reaction and/or drying, or removal of water (or other solvent), is required prior to use of such coatings. In addition they are usually very thin. This makes such known technologies unsuitable for producing a coating which is immediately functional via a rapid low cost continuous process and also unsuitable for producing relatively thick coatings which can exhibit greater swelling behaviour.
U.S. Pat. No. 4,167,464 and U.S. Pat. No. 4,486,489 describe the use of photopolymerisation methods to prepare water absorbent films or fibres from aqueous formulations comprising pre-formed acrylic acid salts as the main component. Since large amounts of water are present in the formulations the speed of the acrylate polymerisation is reduced and this can leave films which are very soft and/or which have a high level of residual tack if the systems are under-cured or not dried by insufficient exposure to the radiation and/or post heating. Indeed there may be relatively higher residual unreacted monomers if not fully cured. In addition such films, after cure, contain relatively high residual water which can be regarded as undesirable per se eg in cables. It can also contribute to a high degree of residual tack and to films being too soft. If drier films are needed from the above formulations, additional heating (drying) is stated as being necessary and this is an obvious inconvenience. The use of high water contents in the formulation can also impair the ability to coat or adhere to some substrates.
It would be desirable to formulate a pourable compisition containing no water, or a small amount of water, which is capable of forming a water swellable coating.
The invention provides pourable liquid compositions which are radiation curable comprising an ethylenically unsaturated polymer having radiation polymerisable functionality dissolved in a monomer, the compositions being water swellable upon radiation curing.
The components of the composition may be used within a wide range of relative proportions and comprise:
an ethylenically unsaturated polymer having radiation polymerisable functionality;
a monomer in which the polymer is dissolved.
The composition may additionally comprise:
one or more photoinitiators and/or photosensitisers;
an organic acid.
The composition may further comprise:
a base;
an inorganic salt;
a small amount of water or organic solvent;
a blowing or foaming agent;
a surfactant or dispersant;
adhesion promoter or tackifying resin;
a fibre or filler:
a crosslinking agent.
Other possible additives include coupling agents, air release agents, inhibitors, wetting agents, lubricants or waxes, stabilisers, antioxidants and pigments.
The final compositions of desirable formulations will depend on a number of factors including the required processing speed, coating thickness, water swelling or blocking response in terms of speed and extent, the nature of the surfaces to which the coating is to be applied, and the nature of solutions in which it is required to function (ie absorb).
The radiation polymerisable polymer, which may be referred to as a prepolymer, as in a polymer which contains ethylenic unsaturation such that it can be further polymerised, may be formed in two stages. Firstly, a monomer or monomers selected from groups below may be polymerised to form a polymer backbone, then secondly unsaturated functionalities are introduced into the polymer backbone. This unsaturated functionality provides the prepolymer with the radiation polymerisable functionality.
The polymer backbone may be formed from monomer or monomers selected from groups consisting of:
C
1
to C
20
alkyl (meth)acrylates, preferably C
1
to C
5
alkyl (meth)acrylates, eg methyl methacrylate;
(meth)acrylates having mono- or multi-carboxylic acid or sulphonic acid functionality eg acrylic acid or anhydride, ss-carboxy ethyl acrylate (ss-CEA), maleic acid, fumaric acid or itaconic acid (or anhydrides thereof;
salts of the acid functional (meth)acrylates with sodium, potassium, ammonium as the counter-ion eg sodium acrylate, ammonium acrylate, sodium 2-sulphoethoxy acrylate. Salts of the acid functional acrylates with other bases including organic bases such as amines eg triethylamine, methyl morpholine, hydroxyethyldiethylamine, triethanolamine, hydroxyethyl morpholine, tris(dimethylaminomethyl) phenol;
(meth)acrylates having a hydroxy functional group eg. hydroxy ethyl acrylate (HEA), hydroxy ethyl (meth)acrylate (HEMA), hydroxy propyl acrylate (HPA); acrylated epoxides eg glycidyl (meth)acrylate, acrylated amino alcohols and alkoxylated amines such as those which may be prepared in-situ by simple mixing of, for example, acid functional acrylate and a hydroxyl functional primary amine;
acrylamide and its derivatives eg N-hydroxymethylacrylamide, N-tris(hydroxymethyl)methyl acrylamide, other N-alkyl or N-alkoxy substituted acrylamides eg N,N-dimethyl acrylamide and acrylamide derivatives such as acrylamidosulphonic acid and its salts;
ether and polyether (meth)acrylates such as monoacrylates having alkoxylated chains eg ethoxy or poly ethylene oxide structure e.g. polyethylene glycol monoacrylates, preferably methoxy polyethyleneglycol 350 methacrylate, polypropylene glycol monoacrylates (egSR 607 from Sartomer Co), ethoxy ethoxyethyl acrylate (EOEOEA), ethyltriethylene glycol methacrylate, ethoxylated phenoxy ethyl acrylate, monomethoxy neopentyl glycol propoxylate monoacrylate (Photomer 8127 from Henkel);
amino-(meth)acrylates or amine-(meth)acrylate salts, eg N,N-dimethylaminoethyl acrylate (DMAEA), tertiary-butylaminoethyl methacrylate; hydrochloride or toluene sulphonate or other salt of DMAEA;
unsaturated acid chlorides, preferably (meth)acryloyl chloride.
Preferred polymer backbones, i.e. the prepolymer as it exists before the introduction of unsaturated functionalities, are formed from monomers selected from groups consisting of:
C
1
to C
20
alkyl (meth)acrylates, preferably C
1
to C
5
alkyl (meth)acrylates, eg methyl methacrylate;
(meth)acrylates having mono- or multi-carboxylic acid or sulphonic acid functionality eg acrylic acid or anhydride, ss-carboxy ethyl acrylate (ss-CEA), maleic acid, fumaric acid or itaconic acid (or anhydrides thereof);
(meth)acrylates having a hydroxy functional group eg. hydroxy ethyl acrylate (HEA), hydroxy ethyl (meth)acrylate (HEMA), hydroxy propyl acrylate (HPA); acrylated epoxides eg glycidyl (meth)acrylate, acrylated amino alcohols and alkoxylated amines such as those which may be prepared in-situ by simple mixing of, for example, acid functional acrylate and a hydroxyl functional primary amine;
acrylamide and its derivatives eg N-hydroxymethylacrylamide, N-tris(hydroxymethyl)methyl acrylamide, other N-alkyl or N-alkoxy substituted acrylamides eg N,N-dimethyl acrylamide and acrylamide derivatives such as acrylamidosulphonic acid and its salts;
ether and polyether (meth)acrylates such as monoacrylates having alkoxylated chains eg ethoxy or
Ciba Specialty Chemicals Water Treatments Ltd.
Mansfield Kevin T.
Pezzuto Helen L.
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