Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1998-07-22
2001-06-05
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C560S083000, C560S183000, C528S049000, C528S073000, C526S301000, C252S609000
Reexamination Certificate
active
06242506
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of radiation curable compositions, and specifically to imparting flame resistance or redardancy to such compositions and the coating, adhesives, and the like, which are the cured products of such compositions.
2. Description of the Prior Art
Radiation curable compositions are a rather recent innovation in the field of coatings and adhesives. The use of ultraviolet (UV) and electron beam (EB) technology is growing rapidly because of the low or zero volatile organic chemical emissions (VOC) obtainable through such technology, and also due to the ability to achieve high productivity. The most popular radiation curable chemistry is based on (meth)acrylates (a convention used herein to refer to both acrylates and methacrylates).
As the field of radiation curable chemistry has developed, there have been several proposals for additives to impart flame resistance, which is a serious need, especially in applications such as airplane and motor vehicle construction, electrical and electronic applications. Bromine and phosphorus-containing additives have been proposed, but so far no one has proposed a commercially acceptable additive which is compatible with the radiation curable compositions, and also reacts with the composition upon cure so as to form an integral part of the cured polymer, and which can not be extracted or otherwise rendered inactive, which is frequently the case with non-reactive bromine or phosphorus based additives. Examples of such non-reactive additives brominated dialkyl phthalate, dioctyl tetrabromophthalate, brominated styrene polymers, and brominated Bisphenol A compounds. The assignee of this application formerly produced a polymerizable fire/flame retarding material under the designation SR640, which was an ethoxylated tetrabromobisphenol A diacrylate. That material was difficult to make, and also suffered from the disadvantage of having very low solubility in typical acrylate monomers and/or oligomers used in radiation curable chemistry.
It has accordingly become an object of this invention to provide a flame retardancy additive for radiation curable compositions which is compatible and reacts with the other components of such compositions.
SUMMARY OF THE INVENTION
These objects, and others which will become apparent from the following disclosure, are achieved by the present invention which in one aspect comprises a compound useful as a reactive additive which imparts flame resistance to radiation curable compositions based on (meth)acrylates which is the reaction product of tetrabromophthalic anhydride or acid and a (meth)acrylic compound.
In another aspect, the invention comprises radiation curable compositions containing such novel flame retardant compound.
Another aspect is a method of providing flame retardancy to such compositions, and one further aspect is the adhesives or coatings which result from radiation curing such compositions.
DETAILED DESCRIPTION OF THE INVENTION
The radiation curable compositions which are made flame resistant according to the invention are any which are known in the art. These compositions usually comprise an oligomer which may be blended with a monomer, and are generally used for coatings and adhesives. The oligomers generally fall into three broad groups of resin, namely epoxy-acrylates, polyester acrylates and polyurethane acrylates.
The epoxy-acrylates include the beta-hydroxy esters which are generated by the reaction of acrylic acid or methacrylic acid with an epoxy resin or epoxy-novolak resin. The polyester acrylates consist of polyesters which have been esterified with acrylic acid to yield a polyester with acrylate ester terminal groups, using well established esterification techniques. The polyurethane acrylates consist of reaction products of a hydroxy-containing acrylate ester, usually 2-hydroxy ethyl acrylate or hydroxy propyl acrylate with an isocyanate prepolymer.
The monomers which are blended with the above acrylic oligomers in order to yield a practical radiation curable formulation in the presence of a suitable photo initiator fall into three groups defined by functionality, and may be mono-, di- or multi-functional.
Multi-functional monomers, usually with a functionality of 3 or 4, generally consists of acrylate esters of trifunctional or tetrafunctional alcohols. Commonly used materials include glycerol triacrylate, trimethylol propane triacrylate, trimethylol ethane triacrylate, pentaerythritol tetracrylate, together with the acrylates of the ethoxylates or propoxylates of the above alcohols.
Difunctional monomers consist usually of the acrylate esters of ethylene glycol or propylene glycol and their oligomers, with tripropylene glycol diacrylate being especially preferred, diacrylates of longer chain alcohols such as hexanediol diacrylate and acrylate esters of cycloaliphatic diols such as the cyclohexane diols.
Monofunctional monomers consist of the acrylate esters of mono functional alcohols such as octanol, nonanol, decanol, dodecanol, tridecanol and hexadecanol both in their linear and branch chain forms. Also included are cyclohexyl acrylate and its alkyl derivatives such as t-butylcyclohexyl acrylate and tetrahydrofurfuryl acrylate. N-vinylpyrrolidone has also been used as a monofunctional monomer.
High functionality monomers give rapid cure speeds and high cross-link density, leading to films of high hardness and tensile strength with excellent chemical resistance. Monofunctional monomers, conversely, give slow cure speeds and low cross-link density, leading to cured films of lower hardness, tensile strength, and with reduced chemical resistance.
“Epoxy-acrylates” are the beta-hydroxy esters which are generated by the reaction of acrylic acid or methacrylic acid with an epoxy resin. Suitable epoxy resins are the resinous products generated by reaction of Bisphenol-A or Bisphenol-F with epichlorohydrin, and consist of a range of materials including liquid and solid resins of varying molecular weights. Especially preferred are the liquid Bisphenol A-epichlorohydrin condensates with a molecular weight in the range of from 300-600. The description “epoxy-acrylate” may also be applied to reaction products of acrylic acid or methacrylic acid with epoxy-novolak resins, that is resin obtained by reaction of epichlorohydrin with a phenol or cresol formaldehyde condensate, and which contain a plurality of glycidyl ether groups with an epoxy functionality greater than 2. Also included are the comparatively low viscosity epoxy acrylates obtained by reaction of epichlorohydrin with the diglycidyl ether of an aliphatic diol or polyol. Examples of materials which may be reacted with acrylic or methacrylic acid include hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether and butanediol diglycidyl ether.
The polyester acrylates consists of polyesters as defined and described in the above description which have been esterified with acrylic acid to yield a polyester with acrylate ester terminal groups, using well established esterification techniques.
Polyurethane acrylates consist of reacting products of a hydroxyl containing acrylate ester, usually 2-hydroxy ethyl acrylate or hydroxy propyl acrylate (1-methyl, 2-hydroxy ethyl acrylate) with an isocyanate prepolymer. Such a prepolymer consists of the reaction products of a polyol, which may be a polyether polyol or a polyester polyol, with a di or polyisocyanate. Suitable polyether polyol include for example polyethylene glycols, polypropylene glycols, ethoxylated or propoxylated glycerol or ethoxylated or propoxylated glycerol or ethoxylated or propoxylated trimethylol propane or trymethylol ethane, all of which may have molecular weights in the range of about 1000 to about 6000. Suitable di or polysocyanates include the aromatic isocyanates such as toluene di-isocyanate or di phenyl methane di-isocyanate, aromatic diisocyanates such as tetramethyl xylylene di-isocyanate, and aliphatic or cycloaliphatic di-isocyanates such as isophorone-di-isocyanate, bis-isocy
Ceska Gary W.
Fan Mingxin
Horgan James
Cozen & O'Connor
Fein Michael B.
Gorr Rachel
LandOfFree
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