Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-08-15
2001-04-17
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S093000, C521S107000, C521S124000, C521S135000, C521S178000, C523S219000
Reexamination Certificate
active
06218442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The invention relates to a foam that resists corrosion and that is useful for reinforcing structural members and the like.
2. Discussion of the Related Art
It is known that a number of industries, e.g., the automobile industry, require parts that are both strong and light-weight. One attempt to achieve this balance between strength and minimal weight provides for hollow metal parts. However, hollow metal parts are easily distorted. Accordingly, it is also known that the presence of structural foam in the cavities of the hollow parts can improve strength and stiffness of such parts.
Generally, such foams comprise a thermosettable resin such as an epoxy resin, a blowing agent and a filler such as hollow glass microspheres. Preferably, these foams have a density of about 20-40 lb/ft
3
(about 0.30-0.65 g/cc) and are able to withstand heat in excess of 175° C., most preferably in excess of 200° C. Optional ingredients indude curatives, processing aids, stabilizers, colorants, and UV absorbers.
Specific formulas for structural foam can vary widely. For example, U.S. Pat. No. 5,575,526 teaches several structural foams based on polyester and epoxy resins. U.S. Pat. No. 5,755,486 disdoses thermally expandable resin-based materials containing, for example, epoxy resin, acrylonitrile-butadiene rubber, calcium carbonate, carbon black, fumed silica, glass spheres, curing agent, accelerator, and blowing agent. Structural reinforcement foams such as, e.g., TEROCORE® (a product of Henkel Surface Technologies) are now used in a variety of industries.
One characteristic of structural reinforcement foams is that they start as expandable resins that form gas pockets (cells) when cured. When exposed to ordinary environmental conditions, these cells can trap salt and water. Salt and water corrode the metal parts, which are commonly in contact with the foam, and the resulting metal oxide degrades the ability of the foam to adhere to the metal. Eventually, the foam is forced from the metal part, thereby weakening the part.
SUMMARY OF THE INVENTION
Surprisingly, the inventors have found that organometallate compounds selected from the group consisting of organic titanates and organic zirconates can act as corrosion inhibitors when added to structural reinforcement foam formulations. That is, the organometallate compounds reduce the amount of corrosion which takes place on a metal surface (particularly a ferrous metal surface such as steel) in contact with a reinforcing foam.
The foamable compositions comprise, in addition to a corrosion-inhibiting amount of one or more organometallate compounds, one or more thermosettable synthetic resins, one or more curatives, and one or more blowing agents. In one especially advantageous aspect of the invention, the foamable composition is in the form of a pliable dough which additionally contains one or more fillers, particularly hollow glass microspheres.
Synergistic improvements in certain properties can be achieved through the use of a combination of different types of organometallate compounds.
DETAILED DESCRIPTION OF THE INVENTION
Organic titanates and zirconates suitable for use as corrosion inhibitors in the present invention are well known in the art and are described, for example, in the following U.S. Pat. Nos. (each of which is incorporated herein by reference in its entirety): 2,984,641; 4,069,192; 4,080,353; 4,087,402; 4,094,853; 4,096,110; 4,098,758; 4,122,062; 4,192,792; 4,261,913; 4,423,180; 4,450,221; 4,512,928; 4,600,789; 4,623,738; 4,634,785; 4,659,848; 4,788,235; 4,792,580; 5,045,575; and 5,707,571. A number of suitable titanates and zirconates are available from commercial sources, such as Ajinomoto Company, Inc., of Japan under the PLENACT trademark and Kenrich Petrochemicals of Bayonne, N.J. under the KEN-REACT trademark, including NZ-37 (a particularly preferred zirconate), NZ-38, LICA 38, LICA 97, KZTPP, CAPRO L 38/H, KR-238M (a particularly preferred titanate which is an amino(meth)acrylate adduct of a tetrasubstituted pyrophosphato titanate; the chemical structure of KR-238M is shown in U.S. Pat. No. 5,340,946, the disclosure of which is incorporated herein by reference in its entirety), KR-55 (a particularly preferred titanate which is a phosphite adduct of a neoalkoxy-substituted titanate; the chemical structure of KR-55 is shown in U.S. Pat. No. 5,045,575, the disclosure of which is incorporated herein by reference in its entirety), KZ-55, KR-41B, KR-46B, KR-TTS, KR-201, KR-33BS, KR-133BS, KR-39BS, KR-139BS, KR-34S, KR-34BS, KR-134S, KR-134BS, KR-44, KR-52S, KR-63S, KR-66S, KR-27S, KR-9S, KR-12, KR-112S, KR-212, KR-38S, KR-138S, KR-2388, KR-58FS, KR-158FS, KR-62ES, KR-262ES, KR-36C, KR-41B, NZ-44, LZ-38 and KR-46B.
Suitable organometallates are characterized in general by having four substituents covalently bonded to titanium or zirconium atoms (i.e., the organometallates are tetrasubstituted) with the four atoms directly bonded to the metal atom being oxygen atoms. As will be discussed in more detail hereinafter, the metal atoms may optionally be complexed by various types of moieties to form adducts.
It is particularly preferred to use one or more titanates and/or zirconates containing at least one neoalkoxy substituent attached to titanium or zirconium such as those described, for example, in U.S. Pat. Nos. 4,600,789; 4,623,738 and 5,045,575.
The neoalkoxy substituent(s) preferably correspond to the general structure
wherein R, R
1
and R
2
may be the same or different and are each a monovalent alkyl, alkenyl, alkynyl, aralkyl, aryl, or alkaryl group having up to 20 carbon atoms or a halogen or ether substituted derivative thereof. R
2
may also be an oxy derivative or an ether substituted oxy derivative of the aforementioned groups. (e.g., C
1-
-C
3
alkoxy, phenoxy). In one embodiment, R
2
is C
1
-C
6
alkyl and R
1
and R
2
are allyloxymethyl (—CH
2
—O—CH
2
—CH═CH
2
). The titanate or zirconate may also be an adduct of a phosphite or other phosphorus-containing moiety. Such moeities may be regarded as complexing or chelating agents, wherein certain functional groups in the entity are associated with the metal atom (Ti or Zr) in the titanate or zirconate. The entity may preferably be a mono or di-substituted hydrogen phosphite. Suitable adducts of this type are described, for example, in U.S. Pat. Nos. 4,080,353; 4,261,913; 4,512,928; 4,659,848; 4,788,235; 4,792,580 and 5,045,575.
Another particularly preferred class of organometallate compound includes amine adducts of titanates and zirconates. The metal atom is preferably substituted with at least one phosphorus-containing substituent selected from the group consisting of phosphite, phosphate and pyrophosphate. In a particularly desirable embodiment, the amine portion of the adduct contains an unsaturated carboxylate functionality such as (meth)acrylate. The commercial product KEN-REACT KR-238M titanate (available from Kenrich Petrochemical) is an example of this type of titanate adduct. Amine adducts of titanates and zirconates are also described in U.S. Pat. Nos. 4,512,928 and 5,340,946.
Sufficient organometallate compound is incorporated into the foamable composition so as to reduce the extent of corrosion which occurs when the structural reinforcement foam formed from the foamable composition is placed in contact with the surface of a metal part. The optimum amount of organometallate compound will vary somewhat depending upon the identity of the organometallate compound(s) selected for use and the type of metal surface, among other factors, but may be readily determined by routine experimentation. Total amounts of organometallate compounds in the range of from about 0.1 to about 2 weight of % based on the total weight of the foamable composition will generally be effective, however.
In one embodiment of the invention, at least two different organometallate compounds are utilized. Even more preferably, at least three different organometallate compounds are utilized. The different organometallate compounds are d
Harrison Bruce Lee
Hilborn Bradley L.
Foelak Morton
Harper Stephen D.
Henkel Corporation
Jaeschke Wayne C.
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