Foamable composition exhibiting instant thixotropic gelling

Details Foamable composition exhibiting instant thixotropic gelling Foamable composition exhibiting instant thixotropic gelling

2001-04-24

2002-09-24

Gorr, Rachel (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

C521S902000, C521S172000, C521S173000, C238S029000, C156S077000, C523S130000, C523S131000

Reexamination Certificate

active

06455605

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a foamable composition comprising at least two parts. More specifically, the first part comprises at least one polyol, at least one thixotropic gelling agent, and at least one blowing agent wherein the first part comprises an effective amount of hydrophobic ingredients and a second part comprising at least one isocyanate. A foam mass can be prepared by a method of combining the polyol component with the isocyanate component substantially free of urethane prepolymer and applying the mixture to a void or substrate. The invention also relates to methods of using the foamable composition in the repair of surface defects or for the reinforcement of structural members such as spike holes left after spike removal from railroad ties during road bed maintenance or repair. The invention further relates to a method of foaming the composition in the presence of water.
BACKGROUND OF THE INVENTION
Materials used to repair defects in structural members should have certain characteristics. The material should be easily applied and should form high strength bonds to structural members made of varying materials. Particularly for outdoor repairs, the repair materials should be usable in many environments including environments having extremes of heat and cold and having the presence of substantial quantities of environmental water.
One particularly important end use for such repair compositions is in the recycle or reuse of railroad ties. Typically in the maintenance of the railroad right of way, the rails along with the tie plates and spikes, are removed from railroad ties which remain in the roadbed. If a new rail is to be spiked to the old tie, it is critical that the railroad tie spike holes be repaired prior to laying the new rail. The presence of spike holes in an old tie can cause problems since if a spike is driven into a portion of the tie near an old spike hole, the driving force of the spike can displace the spike from its intended location into an old hole, displacing the rail, tie plate and spike. In the instance that the spike is driven into an incorrect location substantial economic loss can result in repairing the misaligned rail. If a misaligned rail is not repaired, the defect can cause derailment or other problems. Further, the spike holes can be the source of structural weakness in the tie, allowing water to enter the core of the tie accelerating the degradation.
Mechanical spike hole repair means have been suggested in the art. For example, Moses, U.S. Pat. No. 3,191,864, issued Jun. 29, 1965 teaches a mechanical spike hole insert used by first boring out an old spike hole, installing an insert and driving a new spike into the insert. Newman U.S. Pat. No. 3,716,608, issued Feb. 13, 1973 teaches metallic inserts that can be placed in bored out spike holes with a filling of a synthetic resin into which the spikes can be driven. In another area of repair, Tessenski, U.S. Pat. Nos. 4,070,201 and 4,152,185, issued Jan. 24, 1978 and May 1, 1979 respectively, teach a railroad tie spike hole plugging material and method using a substantial uniform mixture of a granular abrasive material and a granular plastic material which is poured into the hole left after spike removal. The driving force of a spike into the abrasive material generates heat which plasticizes the material resulting in a firm bond of the spike to the material. Mechanical and resin-based hole filling methods tend to be time consuming, expensive and adapted to manual, not automatic application or installation.
Rhodes et al., U.S. Pat. No. 4,295,259, issued Oct. 20, 1981, teaches a method of reusing wooden railroad ties in which the old spike holes are filled with a high-density rigid polyurethane foam injected into the holes. At col. 4, lines 14-20, this reference states that “Manufacturers of polyurethane chemicals caution that both components not be allowed to drop below 55° F. (13° C.) at any time, including shipping and storage. Temperatures below 55° F. (13° C.) apparently have a deleterious effect on the properties of the final product. Temperature control during operation is used to regulate viscosity.”
Other polyurethane foam compositions have been suggested for other uses. For example, Maruyama et al., U.S. Pat. No. 4,264,743, issued Apr. 29, 1981, teaches a polyurethane foam sealing material prepared from a polyisocyanate and a polyol component, a major portion of said polyol component consisting of polyol derived from a dimer acid or castor oil, or a mixture thereof in the presence of a blowing agent, a foam stabilizer, a catalyst, and optionally, a lipophilic filler. As the catalyst, tertiary amines and organotin compounds are preferably used. The sealing materials are suitable for use in fender, ventilator, air conditioning joints and other parts in automobiles, as well as in ships, refrigerators and other assembly products.
Barker et al., U.S. Pat. No. 5,124,367, issued Jun. 23, 1992 teaches a fire retardant composition comprising a dispersion of solid fire retardant additive in a liquid isocyanate-reactive compound having a functionality of from 2 to 8 and an average equivalent weight of from about 31 to about 5000 and, as an anti-settling agent, an effective amount of a fatty acid ester and/or amide such as castor oil. The anti-settling agent is disclosed in an amount of 0.05 to 5%. The composition is useful in the manufacture of fire resistant flexible and rigid foams.
Grimm et al., U.S. Pat. No. 5,470,515, issued Nov. 28, 1995, teaches insulating pipes by application of at least one insulating layer and at least one outer surface layer by rotational molding. A rigid polyurethane foam is used as the insulating layer while a solid polyurethane is used as the surface layer. The rigid polyurethane foam is obtained by the reaction of a) an aromatic isocyanate with b) a polyol component bearing on average at least 3 isocyanate-reactive hydrogen atoms containing: 1. a polyether containing at least two hydroxyl groups and having a molecular weight of 300 to 700, 2. an aliphatic, cycloaliphatic or aromatic polyamine having a molecular weight of 32 to 1,000 as a crosslinking agent and a blowing agent, and optional ingredients. The solid polyurethane is obtained by the reaction of a) an NCO-terminated prepolymer having an NCO content of 5 to 20% obtained by the reaction of 1) 4,4′-diphenyl methane diisocyanate, optionally admixed with 2,4′ and 2,2′-isomers and 0 to 30% by weight components of high functionality with; 2) polyethers containing 2 to 4 OH groups having a molecular weight of 1,000 to 6,000 to which up to 30% by weight of a hydrophobicizing agent, preferably castor oil, has optionally been added with b) a polyol component containing 1) a polyether containing 2 to 4 isocyanate-reactive hydrogen atoms and having a molecular weight of 1,000 to 6,000; 2) 5 to 35% by weight of an aromatic diamine having a molecular weight of 122 to 400; 3) 0 to 5% by weight of an aliphatic or cycloaliphatic diamine having a molecular weight of 60 to 4000; 4) 0 to 30% of a hydrophobicizing agent and 5) optionally auxiliaries and additives.
Doyle et al., U.S. Pat. No. 4,248,811, issued Feb. 3, 1981, teaches equipment and formulations for the filling of ordinary pneumatic tires with a polyurethane foam. Exemplified is a composition wherein component A contains 4,4′-diphenylmethane diisocyanate (MDI) 5 equivalents 665 lbs. and hydroxy-terminated polybutadiene 1 equivalent 1250 lbs. and component B contains hydroxy-terminated polybutadiene 1.1 equivalents 1375 lbs., castor oil 1 equivalent 340 lbs, 1,4-butanediol 1 equivalents 80.1 lbs, silicone surfactant 35 lbs, tertiary amine catalyst 4.5 lbs., lead octoate catalyst 4.5 lbs, and tall oil fatty acid 30.0 lbs. The castor oil is added to compatibilize the polybutadiene.
The use of polyurethane foam in filling spike holes in used railroad ties can present significant problems. The polyurethane foam compositions do not appear to adhere to a spike hole with sufficient adhesion to prevent the accidental remov

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