Everything about Microspheres
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  • Patent Review: Process for forming hollow glass spheres up to 5mm

    Hollow glass microspheres are currently commercially available in sizes of up to 0.2mm, but not larger. William Mathews et. al offer a potential solution for producing larger hollow glass microspheres in patent 3,838,998.   They present a method which would enable the production of hollow glass spheres in sizes up to 5mm in diameter.   As can be seen in the details of the patent, the process is quite complex, and seems to only offer pilot production capability, which would reason why we do not currently see hollow glass spheres in the 0.2-5mm range.

    US Patent: 3,838,998

    PROCESS FOR FORMING HOLLOW GLASS MICRO-SPHERES FROM ADMIXED HIGH AND LOW TEMPERATURE GLASS FORMERS

    Abstract:

    A process for forming hollow glass micro-spheres with walls of controllably variable thickness in a size range of 50 to 5,000 microns, embodying (1) preparation of a water slurry of finely particulated, high temperature and low temperature glass formers; (2) prilling the slurry in a vertical spray drying tower; (3) separating and supporting the individual prilled feed material; (4) heating the feed material to glassification of the high temperature glass former while maintaining appropriate geometry and shell thickness and (5) cooling the finished product. The high temperature glass former is preferably a naturally occurring soda feldspar. The process is particularly adapted to form thicker walled micro-spheres of larger size and high quality.

  • Microspheres: Technologies and Global Markets

    An extensive market research report titled Microspheres: Technologies and Global Markets was recently published by BCC Research marketing firm. The microspheres report examines the spherical microparticles used as components in many advanced materials and composites, in the healthcare and personal care industries, and in many specialty research and development applications. The report estimates the size of the microsphere industry worldwide and makes predictions on a 5-year compound annual growth rate of the microsphere market.

    The global market for microspheres in 2010 is estimated to be $2 billion and growing at a 5–year compound annual growth rate (CAGR) of 11.6%, reaching global sales of $3.5 billion by 2015.

    The use of microspheres in medical technology is a relatively new and evolving industry that will see an estimated compound annual growth rate (CAGR) of 24.5% over the next 5 years. This sector is valued at $481 million in 2010 and is expected to reach $1.4 billion by 2015.

    BCC’s analysis suggests that microspheres will see significantly increased demand in the life–sciences markets, which include medicine and biotechnology. The life sciences sector is worth an estimated $203 million in 2010 and is expected to increase at a 9.3% compound annual growth rate (CAGR) to reach $317 million in 2015.

    The key objective of compiling a market research report on microspheres was to present a comprehensive analysis of the global market for microspheres, including analysis of  supply and demand for microspheres across various industries and geographic regions. The report also includes a technical description of a wide variety of types of microspheres available on the market, as well as relevant industries, technologies and applications.
    • Describes demand for microspheres in six major industries: composites; paints and coatings; oil and gas; cosmetics and personal care; biotechnology and life sciences; and medicine and medical devices.
    • Analyses the demand for 2009 and 2010 and forecasts sales over the next 5 years by industry, type of microspheres, and geographic location.
    • Describes different types of microspheres with respect to their chemical composition, including glass, ceramic, and polymer microspheres, and unique material properties that make them suitable for specific industries and applications.
    • Provides detailed descriptions of major players in the market and their product portfolios.
    • Identifies areas of the market that are expected to experience the highest growth in demand.
    • Discusses the history and structure of the industry, technologies, and factors influencing pricing, supply and demand.
    • Reviews price trends and the relationship between price, quality, end–use application and functionality in the microsphere industry.
    • Examines recent advances in technology, newly evolving markets and companies, as well other factors influencing supply.

    This report can be purchased from BCC Research.

    Report Code: AVM073A, Published: November 2010, Analyst: Yelena Lipovetskaya

  • Patent Review: Use of Adsorbent Carbon Microspheres for Treatment of Irritable Bowel Syndrome

    United States Patent 7,749,497 was recently issued to Ocera Therapeutics, Inc. (San Diego, CA) regarding the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome.

    The patent invention primarily describes the use of adsorbent carbon microspheres for the treatment of irritable bowel syndrome and symptoms associated with it.  Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by altered bowel habits without the presence of detectable structural abnormalities. IBS is fairly common and makes up 20-50% of visits to gastroenterologists.  Most commonly, patients have abdominal pain associated with altered bowel habits that consist of constipation, diarrhea, or both. The other group consists of patients with painless diarrhea.

    One embodiment disclosed herein includes a method of treating one or more symptoms of irritable bowel syndrome by  administering to the subject adsorbent carbon microspheres with a particle size of 0.01mm to about 2 mm to reduce the abdominal discomfort or pain. In one embodiment, the amount of the adsorbent carbon microspheres is sufficient to achieve at least about a 50% reduction in the number of days the subject experiences abdominal pain or discomfort.

    In some of the embodiments, the adsorbent carbon microspheres have a particle size of about 0.05mm to about 0.8 mm. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g or more as determined by a BET method. In some of the above embodiments, the adsorbent carbon microspheres have a specific surface area of about 700 m.sup.2/g to about 2500 m.sup.2/g as determined by a BET method.

    Microsphere Manufacturing Process:

    First, a dicyclic or tricyclic aromatic compound or a mixture thereof having a boiling point of 200.degree. C. or more is added as an additive to a pitch such as a petroleum pitch or a coal pitch. The whole is heated and mixed, and then shaped to obtain a shaped pitch. Thereafter, the shaped pitch is dispersed and granulated in hot water at 70 to 180.degree. C., with stirring, to obtain a microspherical shaped pitch. The aromatic additive is extracted and removed from the shaped pitch by a solvent having a low solubility to the pitch but a high solubility to the additive. The resulting porous pitch is oxidized by an oxidizing agent to obtain a porous pitch subject to heat infusibility. The resulting infusible porous pitch is treated at 800 to 1000.degree. C. in a gas flow such as steam or carbon dioxide gas reactive with carbon to obtain a porous carbonaceous substance.

    The resulting porous carbonaceous substance is then oxidized in a temperature range of 300 to 800.degree. C., preferably 320 to 600.degree. C., in an atmosphere containing 0.1 to 50% by volume, preferably 1 to 30% by volume, particularly preferably 3 to 20% by volume, of oxygen. The substance is thereafter reduced in a temperature range of 800 to 1200.degree. C., preferably 800 to 1000.degree. C., in an atmosphere of a non-oxidizable gas to obtain the final product. More details of suitable production processes and suitable products may be found in U.S. Pat. Nos. 4,681,764 and 6,830,753 and U.S. Application Publication No. 2005/0112114, filed May 26, 2005, all of which are incorporated herein by reference in their entirety. Suitable adsorbent carbon microspheres are commercially available from Kureha Corp., and is sold in Japan under the trade name KREMEZIN.RTM. (also known as AST-120).

    Administration of the Microspheres to the Patient:

    For use as described herein, adsorbent carbon microspheres may be administered to the gut of a subject by any suitable means. In one embodiment, the carbon is administered orally. Formulations for oral administration may include, but are not limited to, free flowing microspheres, granules, tablets, sugar-coated tablets, capsules, suspensions, sticks, divided packages, or emulsions. In the case of capsules, gelatin capsules, or if necessary, enteric capsules may be used. The oral dosage administered to a subject may be any amount suitable to achieve the desired therapeutic result. In some embodiments, the oral dosage in the case of a human is about 1 to 20 g of the adsorbent per day.

  • Patent Review: Preparation of Swellable and Deformable Microspheres

    United States Patent number 7,794,755 was issued on September 14, 2010, describing the process for preparation of swellable and deformable microspheres. The patent is assigned to E.I. du Pont de Nemours and cites Figuly, Mahajan, and Schiffino as inventors.

    A process for producing microspheres was developed that provides microspheres with new combined properties of high density, low fracture, high swell capacity, rapid swell, and deformability following swell. The process is reliable and high yielding, and makes use of a low temperature azo initiator and a small molecule chlorinated solvent as the organic phase. The microsphere preparation made using the process is particularly useful in medical treatments such as embolization.

    The patent describes a need for microspheres with properties that are advantageous for many types of applications, including medical applications. Microspheres with high density, yet a large capacity to swell in an aqueous environment, would be useful for absorption applications such as small-scale spill control and for delivery applications in which they would carry and release active ingredients such as fertilizers, herbicides, pesticides, cosmetics, shampoos, and medications. Microspheres with additional properties of durability and deformability would provide a valuable material for introduction into animals, including humans, for applications such as tissue augmentation, void filling, wound treatment, and embolization. Tissue augmentation involves introduction of materials in a collapsed area to provide a filling function, such as the treatment of scars or wrinkles. Void filling involves introduction of materials into an empty space, such as one created by removal of a tissue mass. Wound treatment involves introduction of materials to stop bleeding, provide padding, deliver medication, and absorb fluids. Such materials are useful especially in emergency situations including accidents and military operations. Embolization treatment involves the introduction of a material into the vasculature in order to block the blood flow in a particular region, and may be used to treat non-cancerous tumors, such as uterine fibroids, and cancerous tumors, as well as to control bleeding caused by conditions such as stomach ulcers, aneurysms, and injury. Blockage may be desired in the case of arteriovenous malformation (AVM), where abnormal connections occur between arteries and veins. Additionally, blockage may be desired for pre-surgical control of blood flow.

    The patented process makes use of a water soluble, low temperature-active azo initiator in an aqueous solution of monomer, crosslinking agent, and emulsifier. A chlorinated organic medium is used in forming a suspension with the aqueous solution. The aqueous solution and organic medium both additionally include protecting colloids. The aqueous solution and organic medium, as well as the mixture of the two, are initially held below the initiation temperature of the azo initiator. The organic medium, which may comprise a chloroform and methylene chloride mixture, should have a high enough boiling temperature that the aqueous soluble azo initiator can be activated to cause polymerization producing microspheres.

    A prevalence of the microspheres are in the size range of about 25 to about 250 microns in diameter, as seen when analyzing a small sample size of microspheres. A heterogeneous size mixture of microspheres may be separated into microsphere samples of specific size ranges, if desired, for specific applications. Microspheres may be separated by methods such as fluidized bed separation and custom sieving, also called screen filtering.

    The swell capacity (amount of water uptake) of microspheres prepared by the described process may vary depending on the amount of crosslinking agent added to the first solution. For example, crosslinking agent may be added in such an amount as to impart a swell capacity to the microspheres of about 50 grams of water per gram of microspheres, an amount to impart a swell capacity of about 70 grams per gram of microspheres, and alternatively an amount to impart a swell capacity of about 100 grams per gram of microspheres.

    An additional attribute of the microspheres prepared by the present process is the capacity to deform following swell. When placed under pressure, the swelled microspheres do not maintain their substantially spherical shape, but compress in the axis of the pressure and expand in the axis that is perpendicular to the pressure. Thus environmental factors, such as pressure of a flowing medium or from the walls of an enclosing container, may cause deformation of the microspheres. In addition, pressure of individual microspheres next to each other may cause deformation. This ability to deform is thought to be imparted and enhanced through the closed cell void structure of the microspheres.

    This ability to deform allows the microspheres to take on a shape of a containing space, and to fill that space. Additionally, deformed microspheres have increased surface area contact with each other, as compared to the contact area between spherical beads. The increased surface area contact between the deformed microspheres provides a more compact structure than is achievable with non-deforming spherical microspheres. This compact structure provides high resistance to penetration. The deformability is highly desirable in some applications such as in embolization treatment, where the deformed, compact microspheres may provide strong blockage at target vascular sites.