Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-01-19
2003-07-01
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C521S082000, C521S091000, C524S492000, C524S493000, C524S495000, C524S496000, C523S216000
Reexamination Certificate
active
06586501
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to aggregates, such as fillers, which are useful in a variety of applications such as elastomeric compositions, polymeric compositions, and the like. The present invention further relates to methods of making these aggregates. The present invention also relates to polymer foams, especially closed-cell polymer foams useful for thermal insulation applications and the like, containing surface-modified carbonaceous fillers. The present invention further relates to novel compositions useful in the manufacture of such polymer foams.
Carbon blacks are widely used as pigments, fillers, and reinforcing agents in the compounding and preparation of rubber and other elastomeric and polymeric compounds. Carbon blacks are particularly useful as reinforcing agents in the preparation of elastomeric compounds used in the manufacture of tires and other articles.
Carbon blacks are generally produced in a furnace-type reactor by pyrolyzing a hydrocarbon feedstock with hot combustion gases to produce combustion products containing particulate carbon black. Carbon black exists in the form of aggregates. The aggregates, in turn are formed of carbon black particles. However, carbon black particles do not generally exist independently of the carbon black aggregate. Carbon blacks are generally characterized on the basis of analytical properties, including, but not limited to, particle size and specific surface area; aggregate size, shape, and distribution; and chemical and physical properties of the surface. The properties of carbon blacks are analytically determined by tests known to the art. For example, nitrogen adsorption surface area (measured by ASTM test procedure D3037- Method A or D4820-Method B) and cetyl-trimethyl ammonium bromide adsorption valve (CTAB) (measured by ASTM test procedure D3765 [09.01]), are measures of specific surface area. Dibutylphtalate absorption of the crushed (CDBP) (measured by ASTM test procedure D3493-86) and uncrushed (DBP) carbon black (measured by ASTM test procedure D2414-93), relates to the aggregate structure. The bound rubber value relates to the surface activity of the carbon black. The properties of a given carbon black depend upon the conditions of manufacture and may be modified, e.g., by altering temperature, pressure, feedstock, residence time, quench temperature, throughput, and other parameters.
Silica is also used as a reinforcing agent (or filler) for elastomers. However, using silica alone as a reinforcing agent for elastomers leads to poor performance compared to the results obtained with carbon black alone as the reinforcing agent. It is theorized that strong filler-filler interaction and poor filler-elastomer interaction accounts for the poor performance of silica. The silica-elastomer interaction can be improved by chemically bonding the two with a chemical coupling agent, such as bis (3-triethoxysilylpropyl) tetra-sulfane, commercially available as Si-69 from Degussa AG, Germany. Coupling agents such as Si-69 create a chemical linkage between the elastomer and the silica, thereby coupling the silica to the elastomer.
When the silica is chemically coupled to the elastomer, certain performance characteristics of the resulting elastomeric composition are enhanced. When incorporated into vehicle tires, such elastomeric compounds provide improved hysteresis balance. However, elastomer compounds containing silica as the primary reinforcing agent exhibit low thermal conductivity, high electrical resistivity, high density, and poor processability.
When carbon black alone is used as a reinforcing agent in elastomeric compositions, it does not chemically couple to the elastomer but the carbon black surface provides many sites for interacting with the elastomer. While the use of a coupling agent with carbon black might provide some improvement in performance to an elastomeric composition, the improvement is not comparable to that obtained when using a coupling agent with silica.
In addition, polymer foams containing filler materials, such as particulate filler materials, are widely known and used in innumerable applications. Closed cell rigid polymer foams, especially polyurethane and polyisocyanurate foams containing particulate filler, such as carbon black or other particulate filler, are widely used for thermal insulation purposes. Foams of this type and their use for thermal insulation purposes are disclosed, for example, in U.S. Pat. No. 5,604,265 to DeVos et al. Also, in U.S. Pat. No. 5,373,026 to Bartz et al, polymer foam structures incorporating carbon black filler are taught for thermal insulation purposes. These patents are incorporated herein in their entirety by reference.
In polymer foams such as, for example, polyurethane and polyisocyanurate foams, cost reduction and/or thermal insulation improvement can be achieved by improving dispersion of filler material in the foam, by controlling foam cell size, and/or by increasing infrared absorption.
In polymer foams, such as polyurethane and polyisocyanurate foams, the windows of the cell structure are believed to be mostly transparent to infrared radiation. The thermal conductivity of these foams should be improved by increasing the infrared absorption of the cell windows. One way to do this is to add infrared absorbing materials, such as carbon black, to the foam in an effort to improve the infrared absorption of the cell windows. However, the distribution of carbon black in these foams is poor and the majority of carbon black resides in the struts of the foam. In other words, the windows of the foams contain little or no carbon black. In fact, it is doubtful that prior work has achieved carbon black concentrations in the windows equivalent to the carbon black concentration found in the struts.
There is a recognized need in the polymer foam industry for foams having improved performance characteristics and/or reduction in the cost and complexity of manufacturing such foams. In certain applications, such as foam insulation, in refrigeration units or other appliances, or for architectural insulation, this need has been increased due to the loss of insulation performance caused by the reduction or elimination of halogenated blowing agents. Some substitute blowing agents are found to produce foams having higher thermal conductivity. Hence, there is an increased need for lowering the thermal conductivity of polymer foams suitable for use in various insulation applications, particularly appliance and architectural thermal insulation uses.
Accordingly, there is a desire to provide improved fillers which will, when incorporated into elastomeric or polymeric materials, provide improved properties and/or overcome one or more of the difficulties described above.
SUMMARY OF THE INVENTION
A feature of the present invention is to provide an aggregate which can be incorporated into elastomeric and/or polymeric materials and provide at least one enhanced property.
Another feature of the present invention is to provide a filler material which can be incorporated into polymeric foams.
Another feature of the present invention is to provide a filler material which can be incorporated into such articles as tires and the like.
It is a further feature of the present invention to provide improved polymer foams. It is a particular feature of the present invention to provide polymer foams having lower thermal conductivity, or, the alternative, lower thermal conductivity per unit cost of the foam. In accordance with certain preferred embodiments of the invention, it is a feature to provide rigid, closed cell polymer foams incorporating surface modified particulate filler materials not previously used for such applications, and being suitable for various insulation purposes.
Additional features and advantages of the present invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invent
Dalton Dennis M.
Kinsman David A.
Krajkowski Lynn M.
Kyrlidis Agathagelos
MacKay Adam L.
Cabot Corporation
Foelak Morton
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