Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-01-19
2004-10-05
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C424S489000, C521S084100, C521S086000, C521S088000, C521S091000, C521S092000, C521S097000, C521S138000, C521S141000, C521S149000, C523S218000, C523S219000
Reexamination Certificate
active
06800668
ABSTRACT:
FIELD OF TEE INVENTION
The present invention relates to methods of manufacturing foam compositions, for use in the preparation of pharmaceuticals or other chemical products. The invention further relates to syntactic foams which are deformable and/or compressible. The syntactic foam compositions of the present invention may be used as carriers, coated or uncoated for chemicals, biologicals, nutraceuticals, growth factors, amino acids, bioactive materials and pharmaceutically active and inactive materials and have pharmaceutical, sanitary, veterinary, agricultural and medical applications. The invention further relates to pharmaceutical and chemical syntactic foam compositions.
BACKGROUND OF THE INVENTION
Syntactic foam is material consisting of prefabricated, manufactured “bubbles” or microsphere fillers in a resin milieu. Syntactic foams having industrial applications are known.
Before the advent of syntactic foams, there were generally two types of foams: blown foams created by the injection of gas; and, self-expanding foams created through the use of chemicals. More recently, materials created by mixing a solid with minute spheres of glass, ceramic, or polymer are finding an increasing range of uses in industrial and high-tech applications.
Blown foams are made by, mixing or injecting a gas into a liquid and causing it to froth like soap bubbles in a bathtub. When the bubbles solidify a foam is created. Typically, self-expanding foams require the use of at least two chemical constituents: one to decompose into a gas to form the bubbles and one to form the walls of the cells. Again, when the bubbles solidify a foam is created.
On the other hand, syntactic foams use prefabricated or manufactured “bubbles” such as microspheres. Some refer to the microspheres as microballoons or even macroballoons. For the purposes of this application the term microspheres is used to include all of these terms and to also include spheres filled with air and spheres which are not filled with air, although it is generally recognized that spheres filled with air are preferred for the preparation of a syntactic foam. The microspheres are mechanically combined with a resin to form a composite material. In this way, the microspheres act as scaffoldings providing structure within the composite material which is formed. The term “syntactic” is derived from the Greek syntaktikos, meaning “to arrange together”. Whereas blown and self-expanding foams develop a fairly random distribution of gas pockets of widely varying sizes and shapes, the porosity of syntactic foams can be much more closely controlled by careful selection and mixing of the microspheres with the resin milieu. Syntactic foams could also be called assembled foams.
While ordinary foams are visibly porous, syntactic foams can have cells so small that the material appears to be a homogeneous solid. Syntactic foams are typically used in deep-submergence vehicles, instrument packaging, electronic gear, cable buoys, floatation collars for deep-water drilling operations, radio frequency and aerospace applications, and by pattern-makers in factories. In other words, the foams are used in industrial applications where, for example, buoyancy is important.
The use of syntactic foams as carriers of coated or uncoated chemicals, biologicals, nutraceuticals, growth factors, amino acids, bioactive materials and pharmaceutically active materials for pharmaceutical, sanitary, veterinary, agricultural and medical applications is not common. Shortcomings in current methods of manufacture of syntactic foams thereby rendering them generally unsuitable for use as carriers particularly in the manufacture of pharmaceuticals include cost, difficulty of fabrication and assembly, high temperatures encountered during fabrication and toxicity of the materials used.
A review of the prior art shows that U.S. Pat. No. 3,856,721 discloses a syntactic foam produced by a controlled curing of a polymer which is a homopolymer of butadiene or a copolymer of butadiene and styrene or the like, at least 40% of which polymer is butadiene. Instead of styrene, a methyl or ethyl derivative may be used. The syntactic foam includes minute hollow spheres which give strength to the foam product and the syntactic foam product has a very low density. The polymeric material of this invention is subjected to a two-stage cure. The first stage being a low-temperature curing system utilizing methylethyl ketone (MEK) peroxide or other peroxides used in lower-temperature cures, cobalt naphthenate, iron naphthenate, and acetylacetone (pentanedione) or the like; the peroxide used in the second stage requiring a higher temperature for activation.
In U.S. Pat. No. 4,250,136, in the preferred form of the invention, a sandwich of composite materials is assembled and placed within a mold having the shape of the article to be formed. The composite sandwich is comprised of the following ingredients: (1) a first or bottom layer of reinforcing material such as fiberglass in woven or mat form; (2) a first layer of initially resilient and open-cell foam containing a liquid thermosetting resin such as epoxy, polyester, vinylester, or the like, is laid over the first reinforcing layer, (3) a second layer of reinforcing material is laid over the first resin-containing, open-cell foam layer; (4) a suitable quantity of uncured syntactic foam having a dough-like consistency is placed over the second reinforcing layer, (5) a third reinforcing layer is placed over the uncured and amorphous syntactic foam; (6) a second layer of liquid, resin-containing, open-cell, resilient foam is overlaid on the third reinforcing layer; and (7) a fourth or upper layer of reinforcing material is laid upon the second resin-containing foam layer. The composite sandwich is then placed within the mold and subjected to suitable heat and pressure to cause the uncured sandwich to assume the internal shape of the mold.
U.S. Pat. No. 4,425,441 discloses a high temperature and flame resistant closed cell polyimide foam material and methods of making the foam. An aromatic tetracarboxylic acid dianhydride is reacted with an oxontine to produce an N-substituted imide, which is then esterified with a suitable alcohol. The resulting liquid is dried and the dry residue is reduced to a uniform powder having particles with diameters generally in the 0.5 to 10 mm range. The powder is preferably further dried, either before or after final size reduction, in a moderate vacuum at moderate temperature to remove any excess residual alcohol. The powder spontaneously expands to form a closed cell foam when heated to a temperature in the range of about 90° to 150° C. for a suitable period. When the powder is expanded in a closed mold, a well consolidated, uniform, closed cell foam product results. When expanded in an unrestricted manner, closed cell “macroballoons” having average diameters between about 0.4 mm to 15 mm result.
U.S. Pat. No. 4,518,717 discloses methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100° C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having selectively variable physical properties.
Prior U.S. Pat. Nos. 4,161,477, 4,183,838 and 4,183,839 disclosed and claimed certain polyimide co
Odidi Amina
Odidi Isa
Cooney Jr. John M.
Intellipharmaceutics Corp.
Licata & Tyrrell P.C.
LandOfFree
Syntactic deformable foam compositions and methods for making does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Syntactic deformable foam compositions and methods for making, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Syntactic deformable foam compositions and methods for making will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3259933