Compositions – Oxidative bleachant – oxidant containing – or generative – Composition containing a stabilizer or a product in the form...
Reexamination Certificate
2002-03-22
2004-03-02
Anthony, Joseph D. (Department: 1714)
Compositions
Oxidative bleachant, oxidant containing, or generative
Composition containing a stabilizer or a product in the form...
C252S186420, C252S186200
Reexamination Certificate
active
06699403
ABSTRACT:
FIELD OF INVENTION
The present invention relates to supported peroxides and a method of forming supported peroxides.
BACKGROUND OF THE INVENTION
Peroxides are used in polymer chemistry for a variety of purposes including, for example, reducing the molecular weight of polymers and vulcanizing rubber. One of the problems associated with the use of peroxides is that in their pure form, peroxides tend to be relatively unstable. Peroxides can break down and lose their activity while in storage. Furthermore, the decomposition and instability of peroxides can present storage and use hazards. For these reasons, peroxides are often diluted with at least one other substance, which improves the stability of the peroxide and facilitates handling. Peroxides that have been diluted with another substance are commonly referred to as “supported peroxides” in the industry.
One known method of forming a supported peroxide product is to melt and spray one or more peroxides onto an inorganic support such as clay or calcium carbonate. The molten peroxide becomes absorbed or adsorbed on the inorganic support and solidifies. The resulting supported peroxide product will be a powder that is easier to handle and is less hazardous than a “pure” peroxide product. One of the drawbacks of inorganic supported grade peroxide products is that the peroxide concentration is generally limited to about 40% by weight, which is the maximum that can be absorbed or adsorbed onto the inorganic support.
Another known method of forming a supported peroxide product is to mill one or more peroxides into a rubber composition to form a master batch product. Master batch products of this type are typically sold as slabs or pellets, which are also easily handled and are substantially less hazardous than pure peroxides. Once again, however, the peroxide concentration for rubber supported grade peroxide products is generally limited to a maximum of about 40% by weight.
Yet another known method of forming a supported peroxide product is to blend one or more peroxides into a molten wax, which is then permitted to cool and solidify. The solidified wax can be granulated or pelletized. It is possible to form supported peroxide products in this manner than have peroxide concentrations of 40% to 70% by weight. One of the drawbacks with wax supported grade peroxide products is that the peroxide must be processed at a high enough temperature to melt the wax, typically above 100° C., which can cause the peroxides to decompose and create a hazardous processing environment. It is also difficult to incorporate other ingredients, such as co-agents and anti-scorch agents, into such compositions.
A need exists for a supported peroxide product that contains a relatively high concentration of peroxide, that can be easily handled, and that can be manufactured at relatively low temperatures.
SUMMARY OF INVENTION
The present invention provides supported peroxides, and a method of forming supported peroxides. Supported peroxides according to the invention are solid particles that comprise an organic peroxide and a metallic soap. In accordance with the method of the invention, supported peroxides are preferably formed by dispersing a mixture comprising at least one peroxide and at least one C
4
to C
30
carboxylic acid into an aqueous solution containing a basic compound that is capable of reacting with the C
4
to C
30
carboxylic acid to form a water soluble soap. Dispersing the mixture into the aqueous solution results in the formation of an emulsion. A polyvalent metal compound that is capable of reacting with the water soluble soap to form a water insoluble metallic soap is then added to the emulsion, which converts the water soluble soap into a water insoluble metallic soap that precipitates from the solution. The organic peroxide is entrained within the precipitate.
Supported peroxide products in accordance with the invention can comprise as much as 90% or more by weight of organic peroxide. Notwithstanding the relatively high concentration of organic peroxide, supported peroxides according to the invention are more heat resistant under typical storage conditions than inorganic supported grades of lower concentration. Supported peroxides according to the invention are in the form of easy-to-disperse powders like inorganic supported grades, but readily melt in polymers like wax-based supported grades. The metallic soap adds lubricity to polymer melts and thus can function as a processing aid. Supported peroxides according to the invention are formed at lower temperatures, and thus are not prone to thermal decomposition during manufacturing.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Supported peroxide compositions according to the present invention comprise solid particles comprising an organic peroxide and at least one metallic soap. Without being held to a particular theory, applicants believe that each of the solid particles comprises a core consisting essentially of the organic peroxide and a coating layer disposed on the core that comprises the metallic soap. Scanning electron micrographs of the particles show that the coating layer is not continuous, meaning that portions of the organic peroxide core are left exposed. Rather than forming a continuous coating, the metallic soap appears to form discrete “platelets” that adhere to and form a mottled cladding over a substantial portion of the surface of the organic core.
Virtually any organic peroxide can be used in the invention. Preferably, however, the organic peroxide will be a solid at standard temperatures and pressures (25° C., 1 ATM) that has a melting point less than about 95° C., and more preferably less than about 50° C. Particularly suitable organic peroxides for use in the invention include, for example, dicumyl peroxide, a, a′-bis(tert-butylperoxy)-diisopropylbenzene, and benzoyl peroxide. It will be appreciated that combinations of two or more organic peroxides can also be used.
The metallic soap in the supported peroxide composition according to the invention comprises a salt of a polyvalent metal and at least one C
4
to C
30
carboxylic acid. Applicants have determined supported peroxide compositions comprising polyvalent salts of at least two different C
4
to C
30
carboxylic acids tend to exhibit superior handling properties (e.g., anti-clumping properties) than supported peroxide compositions comprising a polyvalent salt of only one C
4
to C
30
carboxylic acid. This improvement is noted even when only very small amounts of a “secondary” metallic soap are present in the composition.
The presently most preferred carboxylic acids for use in the invention are stearic acid and/or palmitic acid. These “primary” carboxylic acids are preferably used in combination with smaller amounts (e.g., about 0.01% to about 5.0% by weight) of “secondary” carboxylic acids selected from the group consisting of phthalic acid, terephthalic acid, maleic acid, fumaric acid, benzoic acid, and combinations thereof. Preferred polyvalent metals are calcium, magnesium, and aluminum, with calcium being the presently most preferred polyvalent metal. Preferred metallic soaps include, for example, calcium stearate, magnesium stearate, aluminum stearate, calcium palmitate, magnesium palmitate, aluminum palmitate, calcium phthalate, magnesium phthalate, aluminum phthalate, calcium terephthalate, magnesium terephthalate, aluminum terephthalate, calcium maleate, magnesium maleate, aluminum maleate, calcium fumarate, magnesium fumarate, aluminum fumarate, calcium benzoate, magnesium benzoate, and aluminum benzoate. It will be appreciated that combinations of two or more metallic soaps can also be used.
The supported peroxide composition acc
Dluzneski Peter R.
Gregor Martin J.
Anthony Joseph D.
Geo Specialty Chemicals, Inc.
Rankin, Hill Porter & Clark LLP
LandOfFree
Supported peroxides does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Supported peroxides, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Supported peroxides will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3239423