Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-06-16
2001-06-12
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S332600, C525S332900, C525S333100, C525S333200, C525S333900, C525S343000, C525S371000, C523S202000, C523S215000, C523S216000
Reexamination Certificate
active
06245860
ABSTRACT:
FIELD
This invention relates to a rubber composition which contains substantially hollow, irregular-shaped, inorganic filler particles and/or fragments thereof. An article having a component of such rubber composition may be, for example, a tire or industrial product.
BACKGROUND
Reinforcing fillers are conventionally used in rubber compositions which are, in turn, used as components for various rubber products, including tires and industrial products, including belts and hoses.
Carbon black aggregates are conventionally used for such filler, although precipitated silica aggregates are also sometimes used. Usually a coupling agent is used with the silica to enhance the silica's reinforcing effect for the elastomer. Such reinforcement of rubber compositions is well known to those skilled in such art.
It is to be appreciated that carbon black for rubber reinforcement purposes are typically used in a form of irregularly-shaped aggregates composed of a multiplicity of primary carbon black particles. Usually, the primary carbon black particles themselves are somewhat spherically shaped although they may also be irregularly shaped. Such carbon black aggregates and their use as rubber reinforcement is well known to those having skill in such art.
Hollow silica particles for use in rubber have been disclosed in WO 97/40105 as being prepared by precipitating active silica onto a core material other than silica and then eliminating such core material.
Hollow aerogel microspheres have been disclosed in U.S. Pat. No. 5,227,239 as being prepared by reacting a metal oxide with water and base catalyst in alcohol solvent to result in an alcogel, injecting an inert gas into drops of such alcogel to form hollow alcogel microspheres followed by supercritically drying such alcogel.
Hollow spherical shells prepared by flame combustion is disclosed in U.S. Pat. No. 3,161,468.
Preparation of hollow glass spheres is disclosed in U.S. Pat. No. 4,257,799.
Preparation of hollow porous microspheres from dispersed particle compositions is shown in U.S. Pat. No. 5,397,759.
Preparation of hollow gelled spheres from aqueous sol of ceramic material is shown in U.S. Pat. No. 5,492,870.
It is desired herein to provide for the preparation of a novel filler for rubber compositions, novel rubber compositions and novel products containing at least one component of such rubber composition.
The term “phr” where used herein, and according to conventional practice, refers to “parts of a respective material per 100 parts by weight of rubber, or elastomer”.
In the description of this invention, the terms “rubber” and “elastomer”, where used herein, may be used interchangeably, unless otherwise prescribed. The terms “rubber composition”, “compounded rubber” and “rubber compound”, if used herein, are used interchangeably to refer to “rubber which has been blended or mixed with various ingredients and materials” and such terms are well known to those having skill in the rubber mixing or rubber compounding art.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a rubber composition is provided, as well as an article having at least one component of such rubber composition is provided, wherein said rubber composition is comprised of, based upon 100 parts by weight (phr) of elastomer which is comprised of (A) 100 parts by weight of at least one diene-based elastomer, (B) about 30 to about 110, alternatively about 30 to about 90, phr of reinforcing filler composed of (1) about 20 to about 80, alternatively about 20 to about 50, phr of particles of hollow irregularly-shaped shells of interconnecting domains of inorganic materials and fragments of such hollow shells, (2) and about 10 to about 80, alternatively about 10 to about 60, phr of at least one of (i) rubber reinforcing carbon black (ii) modified rubber reinforcing carbon black, said modified carbon black containing at least one moiety selected from silanol, siloxane, titanium oxide, titanium hydroxide, zirconium oxide, zirconium hydroxide and aluminum hydroxide groups on the surface thereof, (iii) precipitated silica which contains silanol groups on the surface thereof and (iv) aluminosilicate which contains silanol and aluminum hydroxide groups on the surface thereof and (C) a coupling agent having a moiety reactive with said silica, modified carbon black and said shell of inorganic material.
In practice, said inorganic materials for the surface of said carbon black and, therefore, for said hollow shell and fragments thereof, are preferably selected from inorganic materials having reactive hydroxyl groups on their surface selected from at least one of silica, aluminosilicate, titanium oxide, alumina and silicon-magnesium oxide. Preferably, such material is silica which contains silanol groups on the surface thereof or a combination of silica and aluminum which contains both silanol groups and aluminum hydroxide on the surface thereof.
In further accordance with the invention, a method of preparing said component of such article comprises the first preparing said hollow particle reinforcement by forming a modified carbon black having interconnecting domains of at least one of said above-referenced inorganic materials on the surface thereof and removing the resulting carbon black core by oxidation of the carbon black at an elevated temperature followed by blending the resulting hollow particulate material with said elastomers and at least one of said silica, carbon black and modified carbon black.
It is a significant feature of this invention that (1) the substantially hollow particles used in this invention are inherently irregularly shaped by the very nature of the requirement that they are derived from irregularly-shaped carbon black aggregates and, therefore, are not substantially spherical in shape, except as might possibly be found in some individual fragments of such substantially hollow particles, and that (2) the said irregularly-shaped particles are anchored into the elastomer host by use of a coupling agent.
Accordingly, it is considered herein that the practice of this invention is a significant departure from past practice particularly, for example, by providing such irregularly-shaped particles as reinforcement for rubber compositions instead of using substantially spherically-shaped hollow particles—including the anchoring of the irregularly-shaped particles via use of a coupling agent.
In the practice of this invention, it is to be appreciated that the hollow shells may become fragmented (1) during the aforesaid removal of the associated carbon black core or (2) when such shells are mixed under high shear conditions with various rubber mixtures or, alternatively, purposefully pre-crushed prior to mixing with the rubber composition.
Thus, the invention also contemplates the use of mixtures of such shells and fragmented portions thereof.
REFERENCES:
patent: Re. 31992 (1985-09-01), Ancker et al.
Agostini Giorgio
Edme Materne Thierry Florent
Frank Uwe Ernst
Kaes Christian
Visel Friedrich
Harlan R.
The Goodyear Tire & Rubber Company
Wu David W.
Young, Jr. Henry C
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