Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-05-30
2003-05-13
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...
C522S097000, C528S059000, C528S079000, C526S301000
Reexamination Certificate
active
06562881
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to novel urethane (meth)acrylate resins, polyols used to prepare such resins and to free-radically curable compositions employing such resins.
BACKGROUND OF THE INVENTION
Hydrogenated bisphenol A (HBPA) has been used in the preparation of (meth)acrylate capped segmented urethane block copolymers. HBPA is somewhat unique in its role as a urethane extender in preparation of block copolymer urethane acrylate resins. HBPA gives rigid urethane segments that have high temperature transitions due to the high melting point of HBPA (165-175° C.) and these segments are amorphous. These characteristics are believed to contribute heavily to the toughness associated with adhesives derived from such block copolymers.
There are, however, significant drawbacks associated with the use of HBPA in the preparation of segmented urethanes. One such drawback is the fact that HBPA is a high melting solid, it is difficult to handle solid materials in a plant environment and furthermore the reaction between liquids and solids is difficult to moderate. In commercial resin using HBPA, the material is often added as a solid in many portions (in some cases up to 10 additions) to moderate and control the reaction which is oftentimes carried out in a methacrylate solvent monomer. Great care must be exercised to control the temperature so that the solvent monomer does not polymerize but the prepolymer formation is driven to completion so that no solid material is left unreacted.
An additional problem associated with the use of HBPA in the preparation of urethane prepolymers is the fact that the rigid segment prepared by the reaction of HBPA and some diisocyanates, for instance isophorone diisocyanate, is not sufficiently soluble in many (meth)acrylic solvent monomers. Block materials derived from this type of segment often cannot be prepared in a sufficiently high concentration (desirably 50-75% block by weight) to make them useful for formulations. Therefore preparation of modern low color urethanes for radiation curable applications cannot be attained using HBPA as a urethane extender, thus forcing a compromise in either adhesive properties associated with toughened behavior or color development.
Similar problems exist when using other amorphous diols having a high melting point to prepare urethane(meth)acrylate oligomers.
It would be desirable to have a urethane extender diol which provided the property advantages of a high melting point diol with reduced processing problems and improved block resin solubility.
U.S. Pat. No. 5,998,568 describes a alkoxylated diol resin produced by reacting a polyfunctional alcohol, such as cyclohexane dimethanol with a carbonate such as propylene carbonate or 1,2-butylene carbonate. The alkoxylated resin is used in preparing a polyester resin.
Ethoxylates of Hydrogenated bisphenol A or similar diols are known with CA Registry Nos. 195971-69-8, 195971-66-5, and 62580-01-2. A propoxylated hydrogenated bisphenol is known with CA Registry No. 70640-72-1.
Hydrogenated bisphenol A—propylene oxide adduct is mentioned in Chem Abst 110:193978 as a precursor material used in preparing an epoxy resin.
Hydroxycyclohexylalkane polyoxyalkylene compounds are described in Chem Abst 127:266554 as plating bath surfactants.
SUMMARY OF THE INVENTION
The invention is based on the discovery that low level C
3
-C
4
alkoxylation of an amorphous diol gives diol products which have improved processability in forming urethane (meth)acrylate resins without substantial loss of desired physical properties.
In one aspect the invention is a urethane (meth)acrylate resin, obtained by reaction of a polyol component and a polyisocyanate component wherein the polyol component comprises
a first polyol which is an alkoxylate of an amorphous diol having a melting point above about 100° C.;
the alkoxylate is an adduct of propylene oxide, butylene oxide, a mixture of propylene oxide and butylene oxide or a mixture of one or both of propylene oxide and butylene oxide with up to 50 mole % of ethylene oxide, and
the first polyol has an average of from about 1 to about 5 units of alkoxylate per mole of said amorphous diol. The resin is suitably end-capped by reaction of isocyanate groups of the diisocyanate with a hydroxyalkyl (meth)acrylate.
The urethane (meth)acrylate resin may be a block resin oligomer comprising hard segments and soft segments, with the hard segments comprising residues derived from the first polyol and the polyisocyanate and the soft segments comprising residues derived from a co-polyol, suitably an aliphatic diol or triol having a number average molecular weight of from 700 to about 5000.
In a further aspect, the invention comprises free radically curable compositions comprising a resin of the invention. The composition may include additional (meth)acrylate compounds and/or an free-radical initiator, for instance an anaerobic initiator or a photoinitiator. Cured products of such compositions and assemblies adhesively bonded by such cured products are still further aspects of the invention.
The alkoxylated diols as described above and their method of preparation comprise still further aspects of the invention.
These and other aspects of the invention are set forth in the following detailed description and in the claims.
DETAILED DESCRIPTION OF THE INVENTION
Alkoxylated Amorphous Diol
In one aspect the invention is an alkoxylate of an amorphous diol having a melting point above about 100° C. The alkoxylate is an adduct of propylene oxide, butylene oxide, a mixture of propylene oxide and butylene oxide or a mixture of one or both of propylene oxide and butylene oxide with up to 50 mole % of ethylene oxide. The polyol has an average of from about 1 to about 5 units of alkoxylate per mole of said amorphous diol. For ethylene oxide, propylene oxide and butylene oxide, respectively the individual alkoxylate units added to the diol structure may be represented by the substructure formulas:
—(C
2
H
4
O)—;
—(CH
2
CH(CH
3
)O)—,
and
—(CH
2
CH(C
2
H
5
)O)—.
The alkoxylate of the amorphous diol so produced is the first polyol which is used in the preparation of the inventive (meth)acrylate resins.
The alkoxylated amorphous diol is prepared by alkoxylation of the commercial grade amorphous diol using propylene oxide, butylene oxide or mixtures thereof or with up to 50 mole % ethylene oxide. The reaction is suitably carried out neat in the melt at an elevated pressure, suitably from about 25 psi (172 kPa) to about 200 psi (1379 kPa), preferably about 50 psi (345 kPa) to about 100 psi (689 kPa). The reaction is catalyzed with a base such as sodium hydroxide, potassium hydroxide, or an alkali alkoxide. A suitable catalytic amount is from about 0.05 to about 1 weight % of the base catalyst, more preferably about 0.1 to about 0.5% by weight.
The amorphous high melting point diol which is alkoxylated has a melting point above 100° C. A preferred such diol is commercial grade hydrogenated bisphenol A. Other examples of such diols include cyclohexane dimethanol, and hydrogenated dihydroxynaphthalenes. The invention is especially advantageous with amorphous diols which have even higher melting points about 125° C. or higher, and even more so for those having melting points of about 145° C. or higher.
Alkoxylation in this manner will gradually diminish the hard segment high modulus and tensile strength properties and increase elongation properties, which characterize resins made from amorphous high melting diols such as HBPA. Consequently, as a practical matter the a maximum of no more than an average of 5 alkoxylate units per molecule is recommended, more preferably no more than about 3.5 alkoxylate units per molecule. For substantial improvement in resin manufacturing a minimum average of about 1.5 alkoxylate units is recommended. Most preferably the average number of alkoxylate units per molecule of amorphous high melting point diol will be from about 2 to about 3.
In a preferred example, hydrogenated bisphenol A (HBPA) in the melt (165-175° C.) is propox
Glaser David
Jacobine Anthony
Bauman Steven C.
Gorr Rachel
Henkel Loctite Corporation
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