Organometallic compositions

Details Organometallic compositions Organometallic compositions

2002-07-11

2004-07-13

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S055000, C264S109000, C264S136000, C156S331400, C156S331700, C528S056000, C524S398000

Reexamination Certificate

active

06762314

ABSTRACT:

This invention relates to organometallic compositions based on Group IVB metals and which are useful in polyisocyanate compositions especially compositions for binding lignocellulosic material.
The use of organic polyisocyanates as binders for lignocellulosic material in the manufacture of sheets or moulded bodies such as waferboard, chipboard, fiberboard and plywood is well known. In a typical process the organic polyisocyanate, optionally in the form of a solution, dispersion or aqueous emulsion, is applied to the lignocellulosic material which is then subjected to heat and pressure. Isocyanates and polyisocyanates are also used in other applications in which it is necessary to effect curing of the compositions, e.g. in polyurethane coatings.
One suitable polyisocyanate composition is disclosed in PCT Application WO 97/17388. This composition comprises a Group IVB metal compound, preferably a titanium chelate, optionally in combination with a compatibilising compound and/or conventional release agents. Although these compositions perform well as binders for lignocellulosic material and provide good release performance, it is desirable to develop a more economical composition which provides improved stability on storage before use, together with good curing properties and excellent bonding strength when applied to the lignocellulosic material.
U.S. Pat. No. 5,846,897 discloses zirconium compounds with diketones or alkylacetoacetates which catalyse the isocyanate—hydroxy reaction having the chemical structure: Me (X1, X2, X3, X4) wherein Me is zirconium (Zr) or hafnium (Hf) and X1, X2, X3, and X4, are th same or different and selected from the group consisting of a diketone and an alkylacetoacetate having the structures: R
1
COCH
2
COR
2
and R
1
OCOCH
2
COR
2
wherein each of R
1
and R
2
is a branched or linear C1-C20 hydrocarbon and at least one of X1, X2, X3, and X4 is a diketone with structure (II) wherein the total number of carbons in R
1
+R
2
is at least 4.
International Patent Application WO 00/02855 discloses that certain compounds of Group IVB metals can be used to cure isocyanate and polyisocyanate compositions and these compositions are very stable on prolonged storage and economical when used for binding lignocellulosic material. The compounds disclosed are complexes of titanium, zirconium and/or hafnium and a acetoacetate ester in which the molar ratio of Ti or Hf to acetoacetate ester is in the range 1:2.5 to 1:10 or the molar ratio of Zr to acetoacetate ester is in the range 1:4.5 to 1:10 and said acetoacetate ester is an ester of an alcohol containing 1 to 6 carbon atoms.
The physical properties of the materials used in this application are, of course an important factor in selecting appropriate compounds for use in curing the polyisocyanate compositions. One property which affects the handling and storage of the compounds is their flash point. It is desirable for the flash point to be relatively high for safety reasons whilst the melting point should be low enough for the material to be in liquid form under normal conditions for ease of handling.
It is an object of the present invention to provide an organometallic composition which is useful in the curing of polyisocyanate compositions and which has improved handling characteristics compared with the compositions of the prior art.
According to the invention, an organometallic composition comprises a complex of at least one orthoester of a metal having a formula M(ROAcAc)
x
(OR′)
y
in which
(a) M is selected from the group consisting of titanium, zirconium and hafnium;
(b) ROAcAc denotes an ester of an alcohol ROH, in which R comprises an (optionally substituted) C
1-30
cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group or a mixture thereof, with acetoacetic acid;
(c) OR′ is the residue of an alcohol R′OH in which R′ comprises an (optionally substituted) C
7-30
cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group or a mixture thereof, and
(d) x and y are each in the range 1-3 and x+y=4.
M is selected from the group consisting of titanium, zirconium and hafnium and the composition may comprise a mixture of these metals.
The titanium, zirconium or hafnium composition of the invention is described herein as a “complex”. It is believed that some of the acetoacetate ester will be chemically bound to the metal (Ti, Zr and/or Hf) but some may be present as “free” ester. The exact proportions which are bound and free will depend partly upon the exact molar ratios present in the complex and which metal, or metals, are used, but it has been shown that the “free” ester does influence the properties, particularly the stability on storage of polyisocyanate compositions containing the complexes. Preferably the composition contains at least 0.5 moles of free ester per mole of metal, e.g. 0.5-10 moles, more preferably 1-5 moles free ester per mole of metal.
The molar ratio of titanium to total acetoacetate ester (i.e. free ester+complexed ester) in the composition is preferably in the range 1:2.5 to 1:10. When the metal is titanium, the molar ratio is preferably in the range 1:2.5 to 1:8 and more preferably in the range 1:3 to 1:6. When the metal is hafnium or zirconium, the molar ratio is preferably 1:4 to 1:10 and more preferably 1:4 to 1:8, hafnium or zirconium to total acetoacetate ester. For all metals mentioned, the complexes of the invention contain at least one alkoxide group and at least one acetoacetate ester so that x and y are each in the range 1-3 and the total of x+y is 4. When the metal is titanium, both x and y are preferably 2.
Preferably, the complex is a complex of at least one of titanium and zirconium and most preferably M is titanium.
R comprises an (optionally substituted) C
1-30
cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group or a mixture thereof. The preferred acetoacetate esters for preparing the complexes include ethyl acetoacetate, methyl acetoacetate, but esters of higher alcohols, e.g. C
7-30
preferably C
7-12
may be used, e.g. cetyl acetoacetate. The use of esters of higher alcohols is particularly preferred when the complex is to be used in applications in which it is subjected to elevated temperatures, e.g. above the boiling point of EtAcAc (b.p.=181° C.). It is not necessary that the acetoacetate esters are prepared by reacting the alcohol ROH with acetoacetic acid or a derivative thereof, since it is well known that esters may be made by other methods, e.g. by transesterification of another ester. Therefore the term “ester of an alcohol ROH in which R is an (optionally substituted) C
1-30
alkyl group with acetoacetic acid” as used herein is not to be taken to limit the ester to compounds made or obtainable by direct esterification of the acetoacetic acid with the alcohol. The complex can be prepared from more than one acetoacetate ester but preferably only one acetoacetate ester is present in the complex.
Preferred substituents on the R group, include halogens, especially bromine, chlorine or fluorine atoms since these substituted groups may enhance fire retardency properties.
The group R′O is an alkoxide group in which R′ is a substituted or unsubstituted, C
7-30
cyclic, branched or linear, alkyl, alkenyl, aryl or alkyl-aryl group or a mixture thereof. It has been found that selection of such a group, i.e. having at least 7 carbon atoms produces metal complexes having desirable flash-point characteristics i.e. a flash point above 50° C. In preferred complexes of the invention R′ is a C
8-12
alkyl group, e.g. 2-ethyl hexyl or other branched octyl species such as iso-octyl (2,4,4 trimethyl 1 pentanol) or mixed isomers of branched alkyl alcohol species such as the “Exxal™” products, e.g. Exxal 8, available from Exxon. Preferred complexes according to the invention include di(2-ethylhexyloxy)titanium bis(ethylacetoacetate) which has a flash point of about 68° C. and di(2,4,4-trimethyl-1-pentyloxy)titanium bis(ethylacetoacetate) which has a flash point

Affiliated with

Also associated with

Rating

Organometallic compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Organometallic compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organometallic compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3237038