An excisional biopsy device includes a tubular member having a window near a distal tip thereof; a cutting tool, a distal end of the cutting tool being attached near the distal tip of the tubular member, at least a distal portion of the cutting tool being configured to selectively bow out of the window and to retract within the window; and a tissue collection device externally attached at least to the tubular member, the tissue collection device collecting tissue excised by the cutting tool as the biopsy device is rotated and the cutting tool is bowed. An excisional biopsy method for soft tissue includes the steps of inserting a generally tubular member into the tissue, the tubular member including a cutting tool adapted to selectively bow away from the tubular member and an external tissue collection device near a distal tip of the tubular member; rotating the tubular member; selectively varying a degree of bowing of the cutting tool; collecting tissue severed by the cutting tool in the tissue collection device; and retracting the tubular member from the soft tissue. The tubular member may include an imaging transducer and the method may include the step of displaying information received from the transducer on a display device and the step of varying the degree of bowing of the cutting tool based upon the displayed information from the imaging transducer. Alternatively, the imaging transducer may be disposed within a removable transducer core adapted to fit within the tubular member.

1. Field of the Invention
The present invention pertains to the field of soft tissue excisional biopsy devices and methods. In particular, the present invention relates to the field of devices and methods for excising suspicious lesions from soft tissue, such as breast tissue.
2. Description of the Related Art
Breast cancer is a major threat and concern to women. Early detection and treatment of suspicious or cancerous lesions in the breast has been shown to improve long term survival of the patient. The trend is, therefore, to encourage women not only to perform monthly self-breast examination and obtain a yearly breast examination by a qualified physician, but also to undergo annual screening mammography commencing at age 40. Mammography is the only screening modality available today that can detect small, nonpalpable lesions. These nonpalpable lesions may appear as opaque densities relative to normal breast parenchyma and fat or as clusters of microcalcifications.
The conventional method for diagnosing, localizing and excising nonpalpable lesions detected by mammography generally involves a time-consuming, multi-step process. First, the patient goes to the radiology department where the radiologist finds and localizes the lesion either using mammography or ultrasound guidance. Once localized, a radio-opaque wire is inserted into the breast. The distal end of the wire may include a small hook or loop. Ideally, this is placed adjacent to the suspicious area to be biopsied. The patient is then transported to the operating room. Under general or local anesthesia, the surgeon performs a procedure called a needle-localized breast biopsy. In the needle-localized breast biopsy, the surgeon, guided by the wire previously placed in the patient""s breast, excises a mass of tissue around the distal end of the wire. The specimen is sent to the radiology department where a specimen radiograph is taken to confirm that the suspicious lesion is contained within the excised specimen. Meanwhile, the surgeon, patient, anesthesiologist and operating room staff, wait in the operating room for confirmation of that fact from the radiologist before the operation is completed. The suspicious lesion should ideally be excised in toto with a small margin or rim of normal breast tissue on all sides. Obtaining good margins of normal tissue is extremely dependent upon the skill and experience of the surgeon, and often an excessively large amount of normal breast tissue is removed to ensure that the lesion is located within the specimen. This increases the risk of post-operative complications, including bleeding and permanent breast deformity. As 80% of breast biopsies today are benign, many women unnecessarily suffer from permanent scarring and deformity from such benign breast biopsies.
More recently, less invasive techniques have been developed to sample or biopsy the suspicious lesions to obtain a histological diagnosis. The simplest of the newer techniques is to attempt visualization of the lesion by external ultrasound. If seen by external ultrasound, the lesion can be biopsied while being continuously visualized. This technique allows the physician to see the biopsy needle as it actually enters the lesion, thus ensuring that the correct area is sampled. Current sampling systems for use with external ultrasound guidance include a fine needle aspirate, core needle biopsy or vacuum-assisted biopsy devices.
Another conventional technique localizes the suspicious lesion using stereotactic digital mammography. The patient is placed prone on a special table that includes a hole to allow the designated breast to dangle therethrough. The breast is compressed between two mammography plates, which stabilizes the breast to be biopsied and allows the digital mammograms to be taken. At least two images are taken 30 degrees apart to obtain stereotactic views. The x, y and z coordinates targeting the lesion are calculated by a computer. The physician then aligns a special mechanical stage mounted under the table that places the biopsy device into the breast to obtain the sample or samples. There are believed to be three methods available to biopsy lesions using a stereotactic table: (1) fine needle aspiration, (2) core needle biopsy and (3) vacuum-assisted core needle biopsy.
Fine needle aspiration uses a small gauge needle, usually 20 to 25 gauge, to aspirate a small sample of cells from the lesion or suspicious area. The sample is smeared onto slides that are stained and examined by a cytopathologist. In this technique, individual cells in the smears are examined, and tissue architecture or histology is generally not preserved. Fine needle aspiration is also very dependent upon the skill and experience of the operator and can result in a high non-diagnostic rate (up to about 83%), due to inadequate sample collection or preparation.
Core needle biopsy uses a larger size needle, usually 14 gauge to sample the lesion. Tissue architecture and histology are preserved with this method. A side-cutting device, consisting of an inner trough with an outer cutting cannula is attached to a spring-loaded device for a rapid semi-automated firing action. After the lesion is localized, local anaesthetic is instilled and a small incision is made in the skin with a scalpel. The device enters the breast and the needle tip is guided into the breast up to the targeted lesion. The device is fired. First, the inner cannula containing the trough rapidly penetrates the lesion. Immediately following this, the outer cutting cannula rapidly advances over the inner cannula cutting a sample of tissue off in the trough. The whole device is then removed and the sample retrieved. Multiple penetrations of the core needle through the breast and into the lesion are required to obtain an adequate sampling of the lesion. Over 10 samples have been recommended by some.
The vacuum-assisted breast biopsy system is a larger semi-automated side-cutting device. It is usually 11 gauge in diameter and is more sophisticated than the core needle biopsy device. Multiple large samples can be obtained from the lesion without having to reinsert the needle each time. A vacuum is added to suck the tissue into the trough. The rapid firing action of the spring-loaded core needle device is replaced with an oscillating outer cannula that cuts the breast tissue off in the trough. The physician controls the speed at which the outer cannula advances over the trough and can rotate the alignment of the trough in a clockwise fashion to obtain multiple samples.
If a fine needle aspirate, needle core biopsy or vacuum-assisted biopsy shows malignancy or a specific benign diagnosis of atypical hyperplasia, then the patient needs to undergo another procedure, the traditional needle-localized breast biopsy, to fully excise the area with an adequate margin of normal breast tissue. Sometimes the vacuum-assisted device removes the whole targeted lesion. If this occurs, a small titanium clip should be placed in the biopsy field. This clip marks the area if a needle-localized breast biopsy is subsequently required for the previously mentioned reasons.
Another method of biopsying the suspicious lesion utilizes a large end-cutting core device measuring 0.5 cm to 2.0 cm in diameter. This also uses the stereotactic table for stabilization and localization. After the lesion coordinates are calculated and local anesthesia instilled, an incision large enough is permit entry of the bore is made at the entry site with a scalpel. The breast tissue is cored down to and past the lesion. Once the specimen is retrieved, the patient is turned onto her back and the surgeon cauterizes bleeding vessels under direct vision. The incision, measuring 0.5 to larger than 2.0 cm is sutured closed.
The stereotactic table requires awkward positioning of the patient and may be extremely uncomfortable. The woman must lie prone during the entire procedure, which may be impossible for some patients. In addition, the lesion to be biopsied must be in the center working area of the mammography plates. This may be extremely difficult and uncomfortable for the patient if the lesion is very posterior near the chest wall or high towards the axilla.
The woman is subjected to increased radiation exposure as multiple radiographs are required throughout the course of the procedure to: (1) confirm that the lesion is within the working area of the mammography plates, (2) obtain the stereotactic coordinates (at least two views), (3) verify the positioning of the biopsy needle prior to obtaining tissue, and (4) verify that the lesion was indeed sampled. If any difficulty is encountered during the procedure, additional radiographic exposures are required to verify correction of the problem.
Using the core needle biopsy or vacuum-assisted device, bleeding is controlled only by manual pressure. Bleeding is generally not an issue with fine needle aspiration, but is a legitimate complication of the former two methods. Ecchymoses, breast edema and hematomas can occur. This causes increased post-procedural pain and delays healing. Rarely, the patient may require an emergency operation to control and evacuate a tense hematoma.
Another major concern is the possibility of tumor dissemination. The core needle biopsy and vacuum-assisted devices both cut into the tumor and carve out multiple samples for examination. While cutting into the tumor, cancerous cells may be dislodged. Cutting across blood vessels at the same time may allow the freed cancerous cells access to the blood stream, thus possibly seeding the tumor beyond its original locus. The long-term consequences of tumor seeding with the risk of bloodborne metastases are unknown at this time, as the techniques are relatively new. However, documented instances of cancerous cells seeding locally into needle tracks exist. There are numerous reports of metastases growing in needle tracks from previous biopsies of a cancerous mass. Most of these are from lung or liver cancers. However, at least one case of mucinous carcinoma of the breast growing in a needle track has been reported. The long-term consequences of neoplasm seeding into needle tracks are currently unknown, again because the techniques are relatively new. Some recommend excision of the entire needle track, including the skin entry site, during the definitive surgical procedure for a diagnosed cancer, whether it be a lumpectomy or a mastectomy. Others assume that with a lumpectomy, the post-operative radiation therapy will destroy any displaced cancer cells in the needle track. With the trend towards treating very small cancers only by excision and without a post-excision course of radiation therapy, the risk of cancer cells metastasizing and growing in needle tracks is very real.
The large core cutting device (0.5 to 2.0 cm) generally eliminates the risk of needle track seeding as it is designed to excise the lesion intact. A stereotactic table is required with the same inherent awkwardness for the patient, as discussed above. Bleeding is controlled, albeit manually, requiring that the patient wait until the end of the procedure to be turned over. Compression is used to stabilize the breast and localize the lesions. The breast, however, may be torqued and distorted between the compression plates such that when the plates are removed after the biopsy, the large core track left behind may not be straight, but actually tortuous. This can result in permanent breast deformity.
The location of the insertion site into the breast is dictated by the positioning of the breast in the machine and not by the physician. The entry site is usually away from the nipple-areolar complex and is usually located on the more exposed areas of the breast. For the fine needle aspirate, core biopsy and vacuum-assisted devices, the incision is usually very small and the scar almost unappreciable. However, in the case of the large core biopsy device (0.5 to 2.0 cm), a large incision is needed. Such a large incision often results in a non-aesthetically placed scar.
The newer conventional minimally invasive breast biopsy devices have improved in some ways the ability to diagnose mammographically detected nonpalpable lesions. These devices give the patient a choice as to how she wants the diagnosis to be made. Moreover, these devices are substantially less expensive than the older traditional needle-localized breast biopsy. They are not, however, the final solution. Due to the above-discussed problems and risks associated with compression, needle-track seeding, blood borne metastases, bleeding, radiation exposure and awkwardness of the stereotactic table, more refined devices and methods are needed to resolve these issues. Also, the conventional biopsy devices do not consider margins in their excisions and if cancer is diagnosed, the patient must undergo a needle-localized breast lumpectomy to ensure that adequate margins are removed around the cancer. Devices and methods, therefore, must address the problem of obtaining adequate margins so that a second procedure is not required. Margins, moreover, cannot be assessed while the breast is being compressed.
It is, therefore, an object of the present invention to provide devices and methods to efficiently and safely excise suspicious lesions from the breast. It is also an object of the present invention to provide devices and methods that remove the entire lesion intact with the minimum amount of normal tissue surrounding the lesion needed to provide adequate margins. It is a further object of the present invention to provide devices and methods that provide hemostasis in the breast to minimize complications of ecchymosis, hematoma formation, and breast edema. It is another object of the present invention to provide methods and devices to provide intra-tissue ultrasonic guidance to provide real time, in situ monitoring of the procedure. A still further object is to provide devices and methods that allow the physician to minimize the size of the incision though which the procedure is performed and to leave an aesthetically acceptable scar on the breast.
In accordance with the above-described objects and those that will be mentioned and will become apparent below, an embodiment of an excisional biopsy device according to the present invention comprises:
a tubular member having a window near a distal tip thereof;
a cutting tool, a distal end of the cutting tool being attached near the distal tip of the tubular member, at least a distal portion of the cutting tool being configured to selectively bow out of the window and to retract within the window; and
a tissue collection device externally attached at least to the tubular member, the tissue collection device being adapted to collect a tissue sample severed by the cutting tool as the biopsy device is rotated and the cutting tool is bowed.
According to further embodiments, the distal portion of the cutting tool may comprise a thin ribbon sharpened on a leading edge thereof. The leading edge of the thin ribbon may be serrated. The tubular member may comprise an internal guide allowing a proximal portion of the cutting tool to slide therein when a proximal end of the cutting tool is pushed in a distal direction or pulled in a proximal direction. The cutting tool may further comprise an interior lumen; and a plurality of through holes in the distal portion thereof, the through holes being in fluid communication with the interior lumen. The tissue collection device may comprise a bag within which the excised sample of tissue is collected. An opening of the bag may be at least co-extensive with the window in the tubular member. The tissue collection device may be configured to open and to close as the cutting tool is selectively bowed and retracted, respectively. The tissue collection device may comprise a bag attached to the tubular member and to a trailing edge of the distal portion of the cutting tool, the bag opening and closing as the cutting tool is bowed and retracted, respectively. An ultrasound sensor may be mounted within the distal portion of the tubular member, the ultrasound sensor being disposed within the tubular member so as to image tissue about to be cut by the cutting tool as the biopsy device is rotated. The ultrasound sensor may be electrically connected to at one or more data processing and display devices to allow either a real time or a near real time graphical representation of the tissue to be cut. The distal portion of the cutting tool may be electrically connected to an RF or other power source. The distal portion of the cutting tool may comprise a thin wire.
An invasive interventional device for soft biological tissue, according to a further embodiment of the present invention, comprises
a rotatable tubular member having a distal tip adapted to penetrate the tissue;
a work element disposed near the distal tip of the tubular member, the work element acting upon the tissue coming into contact therewith as the tubular member rotates;
an ultrasound transducer disposed near the distal tip of the tubular member and away from the work element, so that the transducer sweeps a plane within the tissue ahead of the work element as the tubular member rotates; and
means for controlling an operation of the work element based upon information gathered from the ultrasound transducer.
According to still further embodiments, the ultrasound transducer may be tuned within a range from about 7.5 MHz to about 20 MHz. The ultrasound transducer may be disposed within the tubular member at an angle xcex1 relative to the work element, the angle xcex1 being no smaller than that necessary to effectively control the operation of the work element in response to the information gathered from the transducer as the tubular member rotates. The angle xcex1 is preferably less than about 180 degrees. The work element may comprise at least one device selected from the group consisting of: an abrasive device, a reciprocating cutting device, a bowing cutting device, an electrosurgical device, a laser device and a vibrating device. The ultrasonic transducer may be connected to at least one data processing and display device to allow an operator of the device to ascertain a structure of the tissue and to control the operation of the work element before the tissue comes into contact with the work element as the device rotates. The work element may comprise a cutting tool, a distal end of the cutting tool being attached near the distal tip of the tubular member, at least a distal portion of the cutting tool being configured to selectively bow out of a window in the tubular member and to retract within the window. The controlling means may include means for selectively bowing and retracting the cutting tool.
According to yet another embodiment, an excisional biopsy method for soft tissue, according to the present invention, comprises the steps of:
inserting a generally tubular member into the tissue, the tubular member including a cutting tool adapted to selectively bow away from the tubular member and an external tissue collection device near a distal tip of the tubular member;
rotating the tubular member;
selectively varying a degree of bowing of the cutting tool;
collecting tissue severed by the cutting tool in the tissue collection device; and
retracting the tubular member from the soft tissue.
The rotating step may be carried out by manually rotating the tubular member. The tubular member may further include an imaging transducer and the method may further include the steps of displaying information received from the transducer on a display device; and varying the degree of bowing of the cutting tool based upon the displayed information from the imaging transducer. The cutting tool may comprise an electrosurgical blade and the method may further comprise the step of varying the power (for example, RF power) applied to the electrosurgical blade based upon information received from the transducer. A step of stabilizing the soft tissue in an uncompressed state prior to the inserting step may also be carried out. A step of controlling the cutting tool to assume a non-extended state may be carried out prior to the inserting step and before the retraction step. The tissue collection device assumes a closed configuration when the cutting tool assumes the non-extended state. The extension of the cutting tool may be controlled by selectively and manually pushing and retracting a proximal end of the cutting tool in the distal and proximal directions, respectively. The cutting tool may comprise an interior lumen and a plurality of through holes in fluid communication therewith, and the method may further comprise the step of delivering at least one fluid to the tissue via the plurality of through holes.
The present invention may also be viewed as an imaging and treatment method for soft tissue, comprising the steps of:
inserting a tubular member into the soft tissue, the tubular member including an ultrasonic transducer mounted near a distal end of the tubular member;
rotating the tubular member within the soft tissue;
displaying an output of the ultrasonic transducer on a display device; and
acting upon the soft tissue based upon the displayed output.
According to further preferred embodiments, the ultrasonic transducer may be tuned to within a frequency range of between about 7.5 MHz to about 20 MHz. The acting step may include a step of severing a selectively variable volume of soft tissue from a main tissue mass. A step of collecting the severed volume of tissue in a tissue collection device mounted externally to the tubular member may also be carried out.
According to a further embodiment, an excisional biopsy device, according to the present invention, comprises:
a tubular member having a first and a second window near a distal tip thereof;
a cutting tool configured to selectively bow out of the first window and to retract within the first window; and
a removable transducer core, the transducer core including an active transducer element configured to face out of the second window when the removable transducer core is fitted within the tubular member.
The removable core may be adapted to snap fit within the tubular member. The active transducer element may, for example, include an ultrasound transducer. The removable transducer core may include a tapered distal tip configured to readily penetrate soft tissue. An external tissue collection device may be attached to the cutting tool and/or to the tubular member. The tubular member may further comprise a recessed section adjacent a trailing edge of the cutting tool, the recessed section being adapted to receive the external tissue collection device. An expandable sheath may also be included, the expandable sheath being adapted to receive the removable transducer core and the tubular member.
The present invention may also be viewed as a method of excising a lesion from soft biological tissue using an excisional biopsy system including a generally tubular member having a cutting tool, a removable transducer core adapted to fit within the tubular member and an expandable sheath, comprising the steps of:
fitting the transducer core through the expandable sheath,
inserting the transducer and sheath though an incision in the tissue;
imaging a target site within the tissue by energizing the transducer core,
removing the transducer core from sheath while leaving the sheath in place within the tissue;
securing the core within the generally tubular member so the core faces outwardly from the tubular member;
sliding the tubular member through the expandable sheath until the cutting tool is positioned adjacent the lesion;
cutting the lesion with the cutting tool; and
retracting at least the tubular member from the incision.
A step of stabilizing the breast in one of an uncompressed and a slightly expanded state prior to the inserting step may also be carried out. The sheath may remain within the tissue after the retracting step and the method may further comprise the step of re-inserting the transducer core within the sheath and imaging the target site to insure that the lesion has been excised. A step of collecting the cut lesion within an external tissue collection device secured to the tubular member may also be carried out. Both the tubular member and the sheath may be retracted from the incision.
The present invention may also be viewed as an excisional biopsy device, comprising:
a single use disposable tubular member having a window near a distal tip thereof, the tubular member including a cutting tool, a distal end of the cutting tool being attached near the distal tip of the tubular member, at least a distal portion of the cutting tool being configured to selectively bow out of the window and to retract within the window; and
a single use disposable tissue collection device externally attached at least to the tubular member, the tissue collection device collecting tissue severed by the cutting tool as the biopsy device is rotated and the cutting tool is bowed.
In yet another embodiment, the present invention is an excisional biopsy device, comprising:
a single use disposable tubular member having a first and a second window near a distal tip thereof, the tubular member including a cutting tool configured to selectively bow out of the first window and to retract within the first window; and
a removable transducer core, the transducer core including an active transducer element configured to face out of the second window when the removable transducer core is fitted within the tubular member.


Unslaked lime, calcium oxide (CaO) or calcium magnesium oxide, CaO.MgO is post added to a ground, colloidal clay product to obtain a resultant product which exhibits greater stability and yield factors than currently available products. The resultant product exhibits a more uniform viscosity-imparting characteristic to a solution to which it is added, while providing greater stability and hence, longer shelf life.

This invention relates to colloidal clays in general and more particularly to a method of increasing the viscosity of such clays.
There are many clays which are found in nature. Basically, clay is a very fine grained, unconsolidated rock material which normally is plastic when wet, but becomes hard and stony when dry. Ordinary clay consists of hydrous silicates of aluminum, together with a large variety of impurities. Geologically, clay can be defined as a rock or mineral fragment, having a diameter less than 1/256 millimeter (0.00016"). This is about the upper limit of size of a particle that can exhibit colloidal properties.
Clays are widely used in the manufacture of tile, porcelain, as is well known and they are further used as filtering aids in oil and in other industrial processes. Clays are also used in drilling operations and are added to water, for example, to thicken the water or water solutions for these purposes and for other purposes as well. Particularly, colloidal clays are highly desirable in many industrial uses and the necessity of providing a colloidal clay is well known in the industry.
Colloidal attapulgite is mined in nothern Florida and southern Georgia and can be processed to give a colloidal grade of clay which is used to thicken water or water solutions for various industrial purposes. There are many techniques described and known in the prior art which operate to convert mined clay to its colloidal form. Certain examples of such techniques can be found by referring to U.S. Pat. No. 3,951,850 entitled "Conversion of Clay to its Colloidal Form by Hydrodynamic Attrition" issued on Apr. 20, 1976.
Essentially, attapulgite and sepiolite are unique in performance among the clay mineral thickeners. The uniqueness resides in the fact that in addition to the ability of these clays to thicken fesh water, they can also be used to thicken water solutions of salts that contain high concentrations of ionic materials.
Clays such as Wyoming bentonite are widely used gelling clays but have disadvantages. These clays will not swell and develop viscosity in the presence of flocculating cations or in low to medium ionic concentrations. For this reason attapulgite and sepiolite clays are often employed as thickening agents for saturated salt water drilling fluids. These fluids contain sodium and chloride ions. The clays can also be employed as thickeners in gypsum inhibited drilling fluids which contain calcium and sulphate ions as well as in suspension fertilizers that contain ions such as ammonium, phosphate, potassium, chloride, nitrate and sulfate. Essentially, these clays can be employed with substances or solutions having ionic types or concentrations that would interfere with the employment and use of the ordinary types of gelling grades of clay such as Wyoming bentonite, hectorite and so on.
Colloidal grades of attapulgite exhibit a considerable degree of variation in their viscosity-imparting characteristics. These variations are indicated by the amount of viscosity a given percentage of clay produces in any solution and how much stirring is necessary to produce the viscosity. In the oil well drilling industry these factors are commonly referred to as the yield in barrels of 15 centipoise mud per ton of clay (B/T) and rate of viscosity yield of the clay respectively. See API "Standard Procedure for Testing Drilling Fluids", API RP 93B 3rd Edition, February 1971 and API "Specification for Oil-Well Drilling-Fluid Materials", API Spec. 13A, Sixth Edition, January 1974. Many theoretical reasons have been offered to account for the above description variations but none have been proven.
It is established practice to improve the rate of yield and sometimes the yield of the clay by subjecting the clay to extrusion during the processing operations. Certain of the crude clays exhibit improvements in yield and rate of yield when additives such as magnesium hydroxide, Mg(OH).sub.29 or hydrated MgO are pugged into them prior to extrusion. In spite of this, very few crude clays exhibit a yield improvement when the above noted additives are post added to a finished product.
The post addition of chemical hydrate lime, Ca(OH).sub.2, results in a considerable improvement in yield and a minor improvement in rate of yield. Colloidal clays treated with Ca(OH).sub.2 are inherently unstable because of the possible air carbonation of the hydrated lime and the reaction of the hydrated lime with the clay. For the abovementioned reasons, lime additions followed by pugging and extrusion degrade the yield of the clay and when hydrated lime is post added, a uniform, intimately intermixture produced by grinding also drops yields. The recommended method of addition is to add the hydrated lime as discrete, easily discernible particles. This technique results in a very poor mixture. Furthermore, to avoid carbonation during storage, the finished, hydrated lime-treated product must be packaged in plasticlined bags.
The above outline represents the current state of manufacturing practice. It should be noted that in spite of the deficiencies of hydrated lime treatment, it is by far the most economical yield improvement method because of the much higher costs of pugging in hydrated MgO plus extrusion practices. In short, the most economically attractive treatment for yield improvement has to be the post addition of an inexpensive chemical additive.
It is therefore an object of the invention to provide a chemical additive which when post added to a colloidal clay substantially increases the yield factors, while further providing improved stability. The additive which is preferably unslaked lime, can be added rapidly and economically.

Methods of improving the viscosity building properties of colloidal clays

International Telephone and Telegraph Corporation


A mousse-forming cleansing shampoo composition having improved conditioning performance comprising:

The present invention relates to mousse-forming shampoo compositions. More particularly, the invention relates to mousse-forming shampoo compositions which include dispersed particles of a conditioning agent such as a silicone or oily material and which impart good conditioning benefits to hair and/or skin.
Mousses are a particularly convenient and pleasant-to-use product form for hair treatment formulations. The product is generally applied to the user""s hand, where it forms a creamy foam which can be easily worked through the hair.
Such mousses have found widespread use in the context of hair styling products. The conventional hair styling mousse generally utilises a water soluble hair styling polymer, water, possibly a conditioning agent, an emulsifier, aesthetic agents and an aerosol propellant. The mousse is typically applied to hair dampened with water, spread through the hair and allowed to dry, giving a temporary set which can be removed by water or by shampooing.
It would be desirable to provide a rinse-off surfactant-based cleansing shampoo in a mousse product form. Consumers appreciate the ease of dispensing and application of a mousse, and the way it can be worked through the hair without getting into the eyes. The latter would be particularly advantageous in the context of formulations based primarily on cleansing surfactants which can sometimes be harsh and irritating to the eyes. However, prior art systems of this type have not achieved much success, largely because the level of conditioning they deliver is insufficient for many people.
The problem stems mainly from the fact that the shampoo in the dispenser must dispense easily. This requirement is generally incompatible with shampoos which incorporate a significant amount of water-insoluble conditioning agents.
For example, silicones are highly desirable water-insoluble conditioning agents for incorporation into shampoos, as is well documented in the literature. However, the problem arises that the usual viscosity level required of the shampoo base in order to prevent the silicone from separating in the formulation is generally too high for effective dispensing of the shampoo from an aerosol formulation. This is manifest as a dispensing problemxe2x80x94the product will tend to dispense slowly and unevenly.
WO95/05158 describes an anionic surfactant based aerosol shampoo formulation. The exemplified formulations do not contain any silicones or other water-insoluble conditioning agents.
We have now found that rinse-off surfactant-based cleansing shampoo compositions can be formulated which deliver excellent conditioning performance from a mousse product form. Surprisingly, compositions of the invention are simple to formulate and can be dispensed easily from an aerosol can simply by agitation of the can where necessary.
The present invention provides a mousse-forming cleansing shampoo composition having improved conditioning performance comprising:
(a) a foamable concentrate comprising:
(i) at least one surfactant;
(ii) dispersed particles of water-insoluble conditioning agent having a particle size of one micron or greater;
(iii) an aqueous carrier; and
(b) an aerosol propellant.
Foamable Concentrate
The mousse-forming cleansing shampoo composition of the invention comprises a foamable concentrate and an aerosol propellant. The term xe2x80x9cconcentratexe2x80x9d will be used to refer to the liquid component of the shampoo composition other than a mousse-forming cleansing shampoo composition having improved conditioning performance comprising:
(A) a foamable concentrate comprising:
(i) at least one surfactant;
(ii) dispersed particles of a water-insoluble conditioning agent having a particle size of 1 micron or greater;
(iii) an aqueous carrier; and
(B) an aerosol propellant. The term xe2x80x9cmoussexe2x80x9d, as used herein, is the same as foam, and refers to the dispensed product unless otherwise specified.
In general, for optimum dispensability of the product, we have found that the viscosity of the foamable concentrate should not exceed 3000 cps.
The viscosity of the foamable concentrate suitably ranges from 1 to 3000, preferably from 10 to 2000, ideally from 100 to 1000 cps.
Viscosity is measured in the conventional manner using a rotary viscometer (Brookfield Viscometer, LVT type, Rotor No.3, 12 rpm after 30 sec. at 25 degrees C.).
In order to achieve such suitable viscosities as described above for the foamable concentrate, it is particularly preferred that the foamable concentrate be substantially free of crystalline suspending agents. By xe2x80x9csubstantially freexe2x80x9d it is generally meant that the level of such agents be about 0.5% or less, preferably about 0.1% or less, ideally no more than about 0.05% by weight of the foamable concentrate.
Crystalline suspending agents include long chain (e.g. C8-C22) acyl derivative materials and long chain amine oxides, such as ethylene glycol long chain esters, alkanolamides of long chain fatty acids, long chain esters of long chain fatty acids, glyceryl long chain esters, long chain esters of long chain alkanolamides, and long chain alkyl dimethyl amine oxides. Common suspending agents of this type are ethylene glycol esters of C14-C22 fatty acids (e.g. ethylene glycol distearate), C16-C22 fatty acid alkanolamides (e.g. stearic monoethanolamide, stearic monoisopropanolamide), C16-C22 alkyl dimethyl amine oxides and N,N-dihydrocarbyl (C12-C22) amidobenzoic acid and salts thereof.
It may in some cases also be preferable, in order to achieve suitable viscosities as described above for the foamable concentrate, to incorporate therein a rheology modifier such as a thinner. Suitable thinners include polyethylene glycol (PEG), polypropylene glycol (PPG), sodium xylene sulphonate, sodium toluene sulphonate and urea. Preferred thinners are PEG 400 and PPG 400.
Conditioning Agent
The foamable concentrate comprises dispersed particles of a water-insoluble conditioning agent having a particle size of 1 micron or greater.
By xe2x80x9cwater insolublexe2x80x9d is meant is that the conditioning agent is not soluble in water (distilled or equivalent) at a concentration of 0.1 wt %, at 25xc2x0 C. and pH 7.
Particle size may be measured by means of a laser light scattering technique, using a 2600D Particle Sizer from Malvern Instruments.
As used herein, the term xe2x80x9cconditioning agentxe2x80x9d includes any material which is used to give a particular conditioning benefit to hair and/or skin. For example, in shampoo compositions for use on the skin, materials such as moisturisers, essential oils, sun-protective or after-sun treatment materials, occlusive oils and the like may be used. In shampoo compositions for use on the hair, suitable materials are those which deliver one or more benefits relating to shine, softness, combability, wet-handling, anti-static properties, protection against damage, body, volume, stylability and manageability.
Preferred conditioning agents for use in compositions of the invention are selected from silicones, high molecular weight hydrocarbon materials, hair conditioning oily or fatty materials and mixtures thereof.
Silicones
Suitable silicones may be one or more polyalkyl siloxanes, one or more polyalkylaryl siloxanes, or mixtures thereof. The silicone is insoluble in the aqueous matrix of the foamable concentrate and so is present as dispersed particles.
The viscosity of the silicone itself preferably ranges from 10,000 cps to 5 million cps.
Suitable polyalkyl siloxanes include polydimethyl siloxanes which have the CTFA designation dimethicone, having a viscosity of up to 100,000 centistokes at 25 degrees C.
These siloxanes are available commercially from the General Electric Company as the Viscasil series and from Dow Corning as the DC 200 series. The viscosity can be measured by means of a glass capillary viscometer as set out further in Dow Corning Corporate Test Method CTM004 Jul. 20, 1970.
Also suitable is polydiethyl siloxane.
Also suitable are silicone gums, such as those described in U.S. Pat. No. 4,152,416 (Spitzer), and on General Electric Silicone Rubber product Data Sheet SE 30, SE 33, SE 54 and SE 76. xe2x80x9cSilicone gumxe2x80x9d denotes polydiorganosiloxanes having a molecular weight of from 200,000 to 1,000,000 and specific examples include polydimethyl siloxane polymers, polydimethyl siloxane/diphenyl/methylvinylsiloxane copolymers, polydimethylsiloxane/methylvinylsiloxane copolymers and mixtures thereof.
Aminofunctional silicones which have the CTFA designation amodimethicone, are also suitable for use in the compositions of the invention, as are polydimethyl siloxanes having hydroxyl end groups (which have the CTFA designation dimethiconol).
The silicone materials described above are preferably incorporated in the foamable concentrate as a pre-formed aqueous emulsion. The average particle size of the silicone material in this emulsion, in the foamble concentrate, and in the fully formulated mousse shampoo composition is generally from 2 to 30 microns, preferably from 2 to 20 microns, more preferably 3 to 10 microns.
The pre-formed emulsion may be prepared by high shear mechanical mixing of the silicone and water, or by emulsifying the insoluble, non-volatile silicone with water and an emulsifierxe2x80x94mixing the silicone into a heated solution of the emulsifier for instance, or by a combination of mechanical and chemical emulsification. A further suitable technique for preparation of the emulsions is emulsion polymerisation. Emulsion polymerised silicones as such are described in U.S. Pat. No. 2,891,820 (Hyde), U.S. Pat. No. 3,294,725 (Findlay) and U.S. Pat. No. 3,360,491 (Axon).
Any surfactant materials either alone or in admixture may be used as emulsifiers in the preparation of the pre-formed silicone emulsions. Suitable emulsifiers include anionic, cationic and nonionic emulsifiers. Examples of anionic emulsifiers are alkylarylsulphonates, e.g., sodium dodecylbenzene sulphonate, alkyl sulphates e.g., sodium, lauryl sulphate, alkyl ether sulphates, e.g., sodium lauryl ether sulphate nEO, where n is from 1 to 20 alkylphenol ether sulphates, e.g., octylphenol ether sulphate nEO where n is from 1 to 20, and sulphosuccinates, e.g., sodium dioctylsulphosuccinate.
Examples of nonionic emulsifiers are alkylphenol ethoxylates, e.g., nonylphenol ethoxylate nEO, where n is from 1 to 50, alcohol ethoxylates, e.g., lauryl alcohol nEO, where n is from 1 to 50, ester ethoxylates, e.g., polyoxyethylene monostearate where the number of oxyethylene units is from 1 to 30.
Typically, a pre-formed emulsion will contain around 50% of, silicone. Pre-formed emulsions are available from suppliers of silicone oils such as Dow Corning, General Electric, Union Carbide, Wacker Chemie, Shin Etsu, Toshiba, Toyo Beauty Co, and Toray Silicone Co. Examples are the material sold as DC2-1310 by Dow Corning (an emulsion of 60,000 cst dimethicone in nonionic surfactant), and the materials sold as X-52-1086, X-52-2127 and X-52-2112 by Shin-Etsu.
The silicone may be present in compositions of the invention as a single material or as a mixture of different silicones, e.g. having different particle sizes and/or functional groups.
The amount of silicone incorporated into the compositions of the invention depends on the level of conditioning desired and the material used. A preferred amount is from 0.01 to about 10% by total weight of silicone based on total weight of the foamable concentrate although these limits are not absolute. The lower limit is determined by the minimum level to achieve conditioning and the upper limit by the maximum level to avoid making the hair and/or skin unacceptably greasy. We have found that an amount of silicone of from 0.5 to 1.5% by total weight of silicone based on total weight of the foamable concentrate, is a particularly suitable level.
When the silicone is incorporated as a pre-formed emulsion as described above, the exact quantity of emulsion will of course depend on the concentration of the emulsion, and should be selected to give the desired quantity of silicone in the foamable concentrate.
High Molecular Weight Hydrocarbon Material
By xe2x80x9chigh molecular weightxe2x80x9d is meant that the weight average molecular weight of the hydrocarbon material is at least 20,000. Suitably it ranges from 20,000 to 1,000,000, preferably 20,000 to 500,000, most preferably 40,000 to 200,000; these materials are especially effective for imparting improved fullness, body and volume to hair.
A preferred class of high molecular weight hydrocarbon materials are per-alk(en)yl hydrocarbon resins. These term xe2x80x9cresinxe2x80x9d is intended to encompass those materials which are solid or semi-solid at room temperature, as well as those which are liquids with high or moderate viscosities. The term does not cover low viscosity materials such as hydrocarbon oils.
EP 567 326 and EP 498 119 describe suitable peralk(en)yl hydrocarbon resins for imparting stylability and enhanced body to hair. Preferred per-alk(en)yl hydrocarbon materials are polymers of butene, isoprene, terpene and styrene, and copolymers of any combination of these monomers, such as butyl rubber (polyisobutylene-co-isoprene), natural rubber (cis-1,4-polyisoprene) and hydrocarbon resins such as mentioned in the Encyclopaedia of Chemical technology by Kirk and Othmer (3rd edition vol.8, pp 852-869), for example aliphatic and aromatic resins and terpene resins.
Especially preferred are polyisobutylene materials of the formula:
H3C xe2x80x94[C(CH3)2xe2x80x94CH2xe2x80x94]mxe2x80x94R
wherein m is 1-5000, preferably 2-2500, and R is:
xe2x80x94CH(CH3)2 or xe2x80x94C(CH3)xe2x95x90CH2
These materials are available from Presperse, Inc. under the PERMETHYL trade name, from Exxon Chemical under the VISTANEX trade name, and from BASF under the OPANOL trade name. Preferred examples include VISTANEX LM-MH and OPANOL B 15.
Suitable methods of making emulsions of particles of high molecular weight hydrocarbon materials such as polyisobutylene resins are described in EP 567 326 and EP 498 119. The process of EP 567 326 is preferred since it is a direct emulsification process with water and a suitable surfactant emulsifier which avoids the need to use a solvent or carrier which is capable of dissolving or dispersing the high molecular weight hydrocarbon material. Such solvents or carriers (e.g. low molecular weight hydrocarbons) can present safety hazards during processing and can destabilise the final formulations into which they are incorporated.
Emulsified high molecular weight hydrocarbon materials for use in hair treatment compositions of the invention generally have an average particle size in the foamable concentrate and in the fully formulated mousse shampoo composition of from 1 to 100 microns, more typically from 1 to 10 microns.
Suitable high molecular weight hydrocarbon emulsions for use in the invention are commercially available in a pre-emulsified form. This is particularly preferred since the pre-formed emulsion can be incorporated into the foamable concentrate by simple mixing.
An example of a suitable pre-formed emulsion is the material PIB 96/003 available from Basildon Chemical. This is an aqueous emulsion of the polyisobutylene resin OPANOL B 15 (ex BASF) with anionic and nonionic surfactant emulsifier.
The high molecular weight hydrocarbon material may be present in compositions of the invention as a single material or as a mixture of different high molecular weight hydrocarbon materials, e.g. of different molecular weights.
The amount of high molecular weight hydrocarbon material incorporated into the compositions of the invention depends on the level of fullness, body and volume enhancement desired and the specific material used. A preferred amount is from about 0.01 to about 2% by total weight of high molecular weight hydrocarbon material based on total weight of the foamable concentrate although these limits are not absolute. The lower limit is determined by the minimum level to achieve the fullness, body and volume enhancing effect and the upper limit by the maximum level to avoid making the hair unacceptably stiff. We have found that an amount of high molecular weight hydrocarbon material of from 0.2 to 0.5% by total weight of high molecular weight hydrocarbon material based on total weight of the foamable concentrate is a particularly suitable level.
When the high molecular weight hydrocarbon material is incorporated as a pre-formed emulsion as described above, the exact quantity of emulsion will of course depend on the concentration of the emulsion, and should be selected to give the desired quantity of high molecular weight hydrocarbon material in the foamable concentrate.
Hair Conditioning Oily or Fatty Material
Hair conditioning oily or fatty materials are preferred conditioning agents in compositions of the invention for adding shine to the hair and also enhancing dry combing and dry hair feel.
Suitable hair conditioning oily or fatty materials will generally have a viscosity at ambient temperature of about 3 million cst or less, preferably about 2 million cst or less, more preferably about 1.5 million cst or less. However, fatty materials which are solid at ambient temperature may also be suitable.
Advantageously, it is not necessary to emulsify the hair conditioning oily or fatty material in order to incorporate it successfully into mousse shampoo formulations according to the invention. In conventional (non-mousse) shampoo formulations, incorporation of oils can present difficulties since the emulsification process tends to cause dissolution of the oil in the shampoo surfactant and consequent disruption of surfactant mesophases. This problem is avoided in mousse shampoo formulations according to the invention, since if necessary they can simply be formulated as two-phase systems in which the oil phase is dispersible by agitation.
Suitable hair conditioning oily or fatty materials are selected from hydrocarbon oils, fatty esters and mixtures thereof.
Hydrocarbon oils include cyclic hydrocarbons, straight chain aliphatic hydrocarbons (saturated or unsaturated), and branched chain aliphatic hydrocarbons (saturated or unsaturated). Straight chain hydrocarbon oils will preferably contain from about 12 to about 19 carbon atoms. Branched chain hydrocarbon oils can and typically may contain higher numbers of carbon atoms. Also suitable are polymeric hydrocarbons of alkenyl monomers, such as C2-C6 alkenyl monomers. These polymers can be straight or branched chain polymers. The straight chain polymers will typically be relatively short in length, having a total number of carbon atoms as described above for straight chain hydrocarbons in general. The branched chain polymers can have substantially higher chain length. The number average molecular weight of such materials can vary widely, but will typically be up to about 500, preferably from about 200 to about 400, more preferably from about 300 to about 350.
Specific examples of suitable hydrocarbon oils include paraffin oil, mineral oil, saturated and unsaturated dodecane, saturated and unsaturated tridecane, saturated and unsaturated tetradecane, saturated and unsaturated pentadecane, saturated and unsaturated hexadecane, and mixtures thereof. Branched-chain isomers of these compounds, as well as of higher chain length hydrocarbons, can also be used. Exemplary branched-chain isomers are highly branched saturated or unsaturated alkanes, such as the permethyl-substituted isomers, e.g., the permethyl-substituted isomers of hexadecane and eicosane, such as 2, 2, 4, 4, 6, 6, 8, 8-dimethyl-10-methylundecane and 2, 2, 4, 4, 6, 6-dimethyl-8-methylnonane, sold by Permethyl Corporation. A further example of a hydrocarbon polymer is polybutene, such as the copolymer of isobutylene and butene. A commercially available material of this type is L-14 polybutene from Amoco Chemical Co. (Chicago, Ill., U.S.A.).
Particularly preferred hydrocarbon oils are the various grades of mineral oils. Mineral oils are liquid mixtures of hydrocarbons that are obtained from petroleum.
Suitable fatty esters are characterised by having at least 10 carbon atoms, and include esters with hydrocarbyl chains derived from fatty acids or alcohols, e.g., monocarboxylic acid esters, polyhydric alcohol esters, and di- and tricarboxylic acid esters. The hydrocarbyl radicals of the fatty esters hereof can also include or have covalently bonded thereto other compatible functionalities, such as amides and alkoxy moieties, such as ethoxy or ether linkages.
Monocarboxylic acid esters include esters of alcohols and/or acids of the formula Rxe2x80x2 COOR in which Rxe2x80x2 and R independently denote alkyl or alkenyl radicals and the sum of carbon atoms in Rxe2x80x2 and R is at least 10, preferably at least 20.
Specific examples include, for example, alkyl and alkenyl esters of fatty acids having aliphatic chains with from about 10 to about 22 carbon atoms, and alkyl and/or alkenyl fatty alcohol carboxylic acid esters having an alkyl and/or alkenyl alcohol-derived aliphatic chain with about 10 to about 22 carbon atoms, and mixtures thereof.
The monocarboxylic acid ester need not necessarily contain at least one chain with at least 10 carbon atoms, so long as the total number of aliphatic chain carbon atoms is at least 10. Examples include isopropyl isostearate, hexyl laurate, isohexyl laurate, isohexyl palmitate, isopropyl palmitate, decyl oleate, isodecyl oleate, hexadecyl stearate, decyl stearate, isopropyl isostearate, dihexyldecyl adipate, lauryl lactate, myristyl lactate, cetyl lactate, oleyl stearate, oleyl oleate, oleyl myristate, lauryl acetate, cetyl propionate, and oleyl adipate.
Di- and trialkyl and alkenyl esters of carboxylic acids can also be used. These include, for example, esters of C4-C8 dicarboxylic acids such as C1-C22 esters (preferably C1-C6) of succinic acid, glutaric acid, adipic acid, hexanoic acid, heptanoic acid, and octanoic acid. Examples include diisopropyl adipate, diisohexyl adipate, and diisopropyl sebacate. Other specific examples include isocetyl stearoyl stearate, and tristearyl citrate.
Polyhydric alcohol esters include alkylene glycol esters, for example ethylene glycol mono and di-fatty acid esters, diethylene glycol mono- and di-fatty acid esters, polyethylene glycol mono- and di-fatty acid esters, propylene glycol mono- and di-fatty acid esters, polypropylene glycol monooleate, polypropylene glycol monostearate, ethoxylated propylene glycol monostearate, polyglycerol poly-fatty acid esters, ethoxylated glyceryl monostearate, 1,3-butylene glycol monostearate, 1,3-butylene glycol distearate, polyoxyethylene polyol fatty acid ester, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters and mono-, di- and triglycerides.
Particularly preferred fatty esters are mono-, di- and triglycerides, more specifically the mono-, di-, and triesters of glycerol and long chain carboxylic acids such as C1-C22 carboxylic acids. A variety of these types of materials can be obtained from vegetable and animal fats and oils, such as coconut oil, castor oil, safflower oil, cottonseed oil, corn oil, olive oil, cod liver oil, almond oil, avocado oil, palm oil, sesame oil, lanolin and soybean oil. Synthetic oils include triolein and tristearin glyceryl dilaurate. Specific examples of preferred materials include cocoa butter and palm stearin.
The hair conditioning oily or fatty material may be present in compositions of the invention as a single material or as a blend.
The hair conditioning oily or fatty material is typically present at a level of from 0.05% to 10%, preferably from 0.2% to 5%, more preferably from about 0.5% to 3%, by total weight of oily or fatty material based on total weight of the foamable concentrate.
Mixtures of any of the above-described conditioning agents may also be used in compositions of the invention. The total level of conditioning agent present in compositions of the invention is typically from 0.05% to 20%, preferably from 0.1% to 10%, more preferably from about 0.5% to 5%, by total weight of conditioning agent based on total weight of the foamable concentrate,.
Surfactant
The foamable concentrate comprises one or more surfactants, to provide a cleansing benefit. Surfactant may also be present as emulsifier for emulsified conditioning agents such as the silicones and high molecular weight hydrocarbon materials described above.
Further surfactant(s) will be present as an additional cleansing ingredient if sufficient for cleansing purposes is not provided as the emulsifier for the emulsified conditioning agent. This further cleansing surfactant may be the same surfactant as the emulsifier, or may be different.
Suitable emulsifiers are well known in the art and include anionic and nonionic surfactants. Examples of anionic surfactants used as emulsifiers are alkylarylsulphonates, e.g., sodium dodecylbenzene sulphonate, alkyl sulphates e.g., sodium lauryl sulphate, alkyl ether sulphates, e.g., sodium lauryl ether sulphate nEO, where n is from 1 to 20 alkylphenol ether sulphates, e.g., octylphenol ether sulphate nEO where n is from 1 to 20, and sulphosuccinates, e.g., sodium dioctylsulphosuccinate.
Examples of nonionic surfactants used as emulsifiers are alkylphenol ethoxylates, e.g., nonylphenol ethoxylate nEO, where n is from 1 to 50, alcohol ethoxylates, e.g., lauryl alcohol nEO, where n is from 1 to 50, ester ethoxylates, e.g., polyoxyethylene monostearate where the number of oxyethylene units is from 1 to 30.
Cleansing surfactants are typically selected from anionic, nonionic, amphoteric and zwitterionic surfactants, and mixtures thereof.
Suitable anionic cleansing surfactants for compositions of the invention include the alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates, N-alkoyl sarcosinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates, alpha-olefin sulphonates and acyl methyl taurates, especially their sodium, magnesium ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups generally contain from 8 to 18 carbon atoms and may be unsaturated. The alkyl ether sulphates, alkyl ether phosphates and alkyl ether carboxylates may contain from one to 10 ethylene oxide or propylene oxide units per molecule, and preferably contain 2 to 3 ethylene oxide units per molecule.
Examples of suitable anionics include sodium lauryl sulphate, sodium lauryl ether sulphate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, ammonium lauryl ether sulphate, sodium dodecylbenzene sulphonate, triethanolamine dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauroyl isethionate, and sodium N-lauryl sarcosinate.
Nonionic cleansing surfactants suitable for use in shampoo compositions of the invention may include condensation products of aliphatic (C8-C18) primary or secondary linear or branched chain alcohols or phenols with alkylene oxides, usually ethylene oxide and generally having from 6 to 30 ethylene oxide groups. Other suitable nonionics include alkylpolyglycosides and mono- or di-alkyl alkanolamides. Examples of the latter nonionics include coco mono- or di-ethanolamide and coco mono-isopropanolamide.
Amphoteric and zwitterionic cleansing surfactants suitable for use in compositions of the invention may include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines), alkyl glycinates, alkyl carboxyglycinates, alkyl amphopropionates, alkylamphoglycinates and alkyl amidopropyl hydroxysultaines. Examples include lauryl amine oxide, cocodimethyl sulphopropyl betaine and preferably lauryl betaine, cocamidopropyl betaine and sodium cocamphopropionate.
The total amount of surfactant (including any used as emulsifier for the conditioning agent) is generally from 3 to 50%, preferably from 5 to 30%, more preferably from 10% to 25%, by total weight of surfactant based on total weight of the foamable concentrate.
Deposition Polymer
The foamable concentrate may contain a deposition polymer for the dispersed particles of conditioning agent. By xe2x80x9cdeposition polymerxe2x80x9d is meant an agent which enhances deposition of the particles of conditioning agent from the shampoo composition of the invention onto the intended site during use, i.e. the hair and/or the scalp. The use of deposition polymers is particularly preferred in conjunction with the silicones and high molecular weight hydrocarbon materials described above.
The deposition polymer may be a homopolymer or be formed from two or more types of monomers. The molecular weight of the polymer will generally be between 5 000 and 10 000 000, typically at least 10 000 and preferably in the range 100 000 to about 2 000 000. The polymers will have cationic nitrogen containing groups such as quaternary ammonium or protonated amino groups, or a mixture thereof.
The cationic charge density of the deposition polymer, which is defined as the reciprocal of the molecular weight of a monomeric unit of the polymer containing one charge, should typically be at least 0.1 meq/g, preferably above 0.8 or higher. The cationic charge density should typically not exceed 4 meq/g. It is preferably less than 3 and more preferably less than 2 meq/g. The charge density can be measured using conductimetric analysis and should be within the above limits at the desired pH of use, which will in general be from about 3 to 9 and preferably between 4 and 8.
The cationic nitrogen-containing group will generally be present as a substituent on a fraction of the total monomer units of the deposition polymer. Thus when the polymer is not a homopolymer it can contain spacer non-cationic monomer units. Such polymers are described in the CTFA Cosmetic Ingredient Directory, 3rd edition. The ratio of the cationic to non-cationic monomer units is selected to give a polymer having a cationic charge density in the required range.
Suitable cationic deposition polymers include, for example, copolymers of vinyl monomers having cationic amine or quaternary ammonium functionalities with water soluble spacer monomers such as (meth)acrylamide, alkyl and dialkyl (meth)acrylamides, alkyl (meth)acrylate, vinyl caprolactone and vinyl pyrrolidine. The alkyl and dialkyl substituted monomers preferably have C1-C7 alkyl groups, more preferably C1-3 alkyl groups. Other suitable spacers include vinyl esters, vinyl alcohol, maleic anhydride, propylene glycol and ethylene glycol.
The cationic amines can be primary, secondary or tertiary amines, depending upon the particular species and the pH of the composition. In general secondary and tertiary amines, especially tertiary, are preferred.
Amine substituted vinyl monomers and amines can be polymerized in the amine form and then converted to ammonium by quaternization.
Suitable cationic amino and quaternary ammonium monomers include, for example, vinyl compounds substituted with dialkyl aminoalkyl acrylate, dialkylamino alkylmethacrylate, monoalkylaminoalkyl acrylate, monoalkylaminoalkyl methacrylate, trialkyl methacryloxyalkyl ammonium salt, trialkyl acryloxyalkyl ammonium salt, diallyl quaternary ammonium salts, and vinyl quaternary ammonium monomers having cyclic cationic nitrogen-containing rings such as pyridinium, imidazolium, and quaternized pyrrolidine, e.g., alkyl vinyl imidazolium, alkyl vinyl pyridinium, and alkyl vinyl pyrrolidine salts. The alkyl portions of these monomers are preferably lower alkyls such as the C1-C3 alkyls, more preferably C1 and C2 alkyls.
Suitable amine-substituted vinyl monomers for use herein include dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide, and dialkylaminoalkyl methacrylamide, wherein the alkyl groups are preferably C1-C7 hydrocarbyls, more preferably C1-C3, alkyls.
The deposition polymer can comprise mixtures of monomer units derived from amine- and/or quaternary ammonium-substituted monomer and/or compatible spacer monomers.
Suitable deposition polymers include, for example: cationic copolymers of 1-vinyl-2-pyrrolidine and 1-vinyl-3-methylimidazolium salt (e.g., Chloride salt) (referred to in the industry by the Cosmetic, Toiletry, and Fragrance Association, xe2x80x9cCTFAxe2x80x9d. as Polyquaternium-16); copolymers of 1-vinyl-2-pyrrolidine and dimethylaminoethyl methacrylate (referred to in the industry by CTFA as Polyquaternium-11); cationic diallyl quaternary ammonium-containing polymers including, for example, dimethyldiallylammonium chloride homopolymer (referred to in the industry (CTFA) as Polyquaternium 6); mineral acid salts of amino-alkyl esters of homo-and co-polymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms, as described in U.S. Pat. No. 4,009,256; and cationic polyacrylamides as described in UK Application No. 9403156.4.
Other cationic deposition polymers that can be used include cationic guar gum derivatives, such as guar hydroxypropyltrimonium chloride (Commercially available from Celanese Corp. in their JAGUAR trademark series).
Examples are JAGUAR C13S, which has a low degree of substitution of the cationic groups and high viscosity. JAGUAR C15, having a moderate degree of substitution and a low viscosity, JAGUAR C17 (high degree of substitution, high viscosity), JAGUAR C16, which is a hydroxypropylated cationic guar derivative containing a low level of substituent groups as well as cationic quaternary ammonium groups, and JAGUAR 162 which is a high transparency, medium viscosity guar having a low degree of substitution.
Preferably the deposition polymer is selected from cationic polyacrylamides and cationic guar derivatives. Particularly preferred deposition polymers are JAGUAR C13S with a cationic charge density of 0.8meq/g. Other particularly suitable materials include JAGUAR C15, JAGUAR C17 and JAGUAR C16 and JAGUAR C162.
The deposition polymer may be present in an amount of from 0.01 to 10%, preferably from 0.01 to 1%, more preferably from about 0.04 to about 0.5%, by weight of deposition polymer based on total weight of the foamable concentrate.
Aqueous Carrier
The foamable concentrate comprises an aqueous carrier, water forming the continuous phase in which the particles of water-insoluble conditioning agent are dispersed. Water is generally present in an amount of from about 20 to about 99% by weight based on total weight of the foamable concentrate.
Propellant
Compositions of the invention contain an aerosol propellant (B). This agent is responsible for expelling the other materials from the container and forming the mousse character.
The propellant gas can be any liquefiable gas conventionally used for aerosol containers. Examples of suitable propellants include dimethyl ether, propane, n-butane and isobutane, used singly or admixed. Other examples of propellants are nitrogen, carbon dioxide, compressed air and fluorohydrocarbons such as the material sold by Du Pont under the trade name DYMEL 152a.
The amount of the propellant gases is governed by normal factors well known in the aerosol art. For mousses the level of propellant is generally from about 3 to about 15%, optimally from about 4 to about 10% , by total weight of propellant based on total weight of the final mousse shampoo composition, for creamy foam and good sensory feel.
Optional Ingredients
Compositions of this invention may contain any other ingredient normally used in hair treatment formulations. These other ingredients may include hair styling resins, colouring agents, antifoam agents, proteins, moisturising agents, antioxidants, fragrances, antimicrobials and sunscreens. Each of these ingredients will be present in an amount effective to accomplish its purpose.
Packaging
Compositions of the invention are typically prepared by charging a suitable pressurisable container with the foamable concentrate, then sealing the container and charging it with propellant (B) according to conventional techniques.

Abstract: (A) a foamable concentrate comprising:

Abstract: (i) at least one surfactant;

Abstract: (iii) an aqueous carrier; and

Abstract: (B) an aerosol propellant.

Unilever Home and Personal Care USA, division of Conopco, Inc.


Nanocomposite compositions comprising organically modified clays and polyolefins or copolymers containing repeat units derived from olefins have flame retardant or flame resistant properties. Sheets and laminates of the nanocomposite can be utilized wherever flame retardant properties are desired.

The present invention relates to a nanocomposite composition, comprising polyolefins and organically modified clay, which exhibits flame retardant and flame resistant properties. The composition can be formed into a sheet or film. The sheet can further be utilized in a multi-layer laminate. Both sheets and laminates are flame retardant and are suitable for use as roofing membranes and protective coverings.
Traditional flame retardants include numerous halogenated organic compounds which extinguish the ignition (flame) source and inhibit chemical decomposition in the flame and inorganic materials such as aluminum trihydrate which release volatiles such as water which cause the flame to extinguish.
U.S. Pat. No. 4,317,737 relates to polyolefin lubricant base oils which can be gelled by layer and chain type overtreated higher dialkyl dimethyl ammonium clays preferably containing a minimum of 12% excess of the quaternary ion moiety over their ion exchange capacity. For example, an overtreated dihydrogenated ditallow ammonium montmorillonite containing a 22% excess of the quaternary ion can be used to prepare a polydecene based grease although it does not gel mineral oil lubricants.
U.S. Pat. No. 4,434,075 relates to an organophilic clay gellant which comprises the reaction product of an organic cation compound, an organic anion, and a smectite-type clay having a cation exchange capacity of at lease 75 milliequivalents per 100 grams of said clay. The organic cation compound has the formula:
wherein R1 is selected from the group consisting of a xcex2,xcex3 unsaturated alkyl group and a hydroxyalkyl group having 2 to 6 carbon atoms and mixtures thereof; R2 is a long chain alkyl group having 12 to 60 carbon atoms; R3 and R4 are individually selected from the group consisting of a xcex2,xcex3 unsaturated alkyl group, a hydroxyalkyl group having 2 to 6 carbon atoms, an aralkyl group, an alkyl group having from 1 to 22 carbon atoms and mixtures thereof; X is selected from a group consisting of phosphorous and nitrogen. The reaction is carried out in a manner such that an organic cation-organic anion complex is intercalated with the smectite-type clay and the cation exchange sites of the smectite-type clay are substituted with the organic cation.
U.S. Pat. No. 4,582,866 relates to flame retardant thermoplastic multi-block copolyester elastomer compositions containing a bromine-containing flame retardant; antimony trioxide; and an organophilic clay which is the reaction product of at least one quaternary ammonium salt with a smectite clay.
U.S. Pat. No. 4,683,259 relates to resin-containing compositions, e.g. unsaturated polyester or epoxy resin compositions, are prepared using an organoclay of improved dispersibility. The organoclay is prepared by suspending a smectite clay in water to form a fluid suspension; treating the suspension with a solution of an inorganic salt, the cation of which has a valency of at least two, the concentration of the salt being such as to flocculate the smectite clay substantially completely; mixing the suspension of the flocculated smectite clay with a quaternary ammonium compound, at least one of the four alkyl groups of which has from 10 to 24 carbon atoms; and dewatering the resultant product.
U.S. Pat. No. 5,475,041 relates to a flame retardant composition which is provided comprising a normally flammable polyolefin or olefin copolymer, and a flame retardant amount of melamine or salt thereof, a polyphenlyene oxide and a silicaceous material.
U.S. Pat. No. 5,718,841 relates to an organophilic clay comprising the reaction product of:
(a) a smectite-type clay; and
(b) a quaternary ammonium compound or compounds selected from the group consisting of:
wherein R1 is an unsaturated alkyl-ester group having 8 to 30 carbon atoms as described below and R2, R3 and R4 are independently selected from the group consisting of (i) R1; (ii) long chain linear or branched alkyl (including methyl). Aliphatic or aromatic groups having 1 to 30 carbon atoms (such groups can also include hydroxylated groups); (iii) aralkyl groups, which are benzyl and substituted benzyl moieties, including such groups having fused ring moieties having linear chains or branches of 1 to 30 carbon atoms; (iv) aryl groups such as phenyl and substituted phenyl including fused ring aromatic substitutents; (v) beta, gamma unsaturated groups having six or less carbon atoms or hydroxyalkyl groups having 2 to 6 carbon atoms ; and (vi) hydrogen; and M is an anion selected from the group consisting of chloride, methylsulfate, acetate, iodide and bromide.
U.S. Pat. No. 5,728,764 relates to organoclay compositions which comprise the reaction product of a smectite-type clay having an ion exchange capacity of at least 50 meq. wt. per 100 g. clay (active basis), and an alkoxylated quaternary ammonium compound having one or two alkoxylated chains containing 0-10 moles ethylene oxide and 3-15 moles of propylene or butylene oxide residues are useful thixotropic materials, especially for the preparation of aqueous systems.
U.S. Pat. No. 5,773,502 relates to a flame retardant composition comprising: (a) a thermoplastic polyester and copolyester material, a halogenated organic fire retardant, antimony oxide, organo clay, and a fluorocarbon polymer. Also provided are compositions comprising glass fibers and stabilizers.
Organically modified clays are distinguished from halogenated flame retardants in that the clays generally form a nanometer scale composite when mixed with polyolefins, which exhibit enhanced fire retardant properties. The resulting nanocomposites do not sag or drip when exposed to a flame source, but hold their shape and inhibit flame spreading. The nanocomposite compositions can be formed into a sheet or laminate and are suitable for numerous applications including roofing membranes.
Titles have been provided in this application solely for illustration and do not limit the scope of the invention in any manner.
The compositions of the present invention comprise a polyolefin material integrated with microscopic or nanosize particles of an organoclay material, which form a nanocomposite having enhanced flame retardant or resistant properties when compared to utilizing polyolefins alone. As used herein, nanocomposite is generally defined as substantially randomly dispersed particles of nanosized organoclay particles in a continuous polymeric (i.e. polyolefin) matrix.
The nanocomposites of the present invention should not be confused with ordinary compositions containing unmodified clay, i.e. natural clay and a polymer where the clay simply acts as a non-reinforcing filler, and has negligible impact on physical properties. However, the flame retardant compositions of the present invention can contain other components which also react or interact with the polymer as on a nanoscale level. The flame retardant compositions of the present invention are preferably melt processed.
The polyolefins utilized in the present invention are thermoplastic polymers or rubbers derived from one or more simple olefins, which have a total of from 2 to about 8 carbon atoms, or copolymers containing repeat units derived from an olefin. Carboxylic acid functionalized polyolefin polymers or copolymers can also be utilized containing up to about 8 percent by weight and preferably from about 1 percent by weight to about 5 percent by weight of the acid wherein the unsaturated acid contains a total of from 2 to about 10 carbon atoms such as acrylic acid, maleic acid, etc., or anhydrides thereof. Examples of polyolefins suitable for the present invention include polyethylene (including low-density, high-density, high molecular weight, ultra-high molecular weight, linear-low-density, very-low density, etc.), maleated polypropylene, polypropylene, polybutylene, polyhexalene, polyoctene, and copolymers, combinations or blends thereof. Examples of copolymers containing repeat units derived from olefins include but are not limited to ethylene-vinyl-acetate (EVA) copolymers.
Preferred polyolefins or copolymers include polyethylene, maleated polypropylene, maleated polyethylene, polypropylene, EVA, copolymers of ethylene and octene, and ethylene-propylene rubber, that is, copolymers of ethylene and propylene. The ethylene propylene rubber that is utilized in the present invention generally contains from about 10 to about 90 weight percent ethylene and from about 90 to about 10 weight percent propylene, and desirably from about 15 to about 85 weight percent ethylene and about 85 to about 15 weight percent propylene. The ethylene and octene copolymer utilized in the present invention generally contains from about 10 to about 90 weight percent ethylene and from about 90 to about 10 weight percent octene, desirably from about 20 to about 80 weight percent ethylene and from about 80 to about 20 percent octene, and preferably from about 30 to about 70 weight percent ethylene and from about 70 to about 30 weight percent octene.
In the present invention, it is desirable to use an organically modified clay, or organoclay which will form a nanocomposite with the polyolefin. The organically modified clays are generally prepared by reacting a clay with an organic cation or cations provided by specific quaternary ammonium compounds. The polyolefin and organoclay are intimately mixed and dispersed on a microscopic or nanoscale level resulting in a composition having increased heat and flame resistance. The organo clays of the present invention generally have a particle size from about 1 to about 10,000 nanometers, desirably from about 100 to about 2,000 nanometers, and preferably from about 200 to about 500 or 1,000 nanometers.
The organoclays of the present invention at least differ from ordinary untreated clays in the fact that the untreated clays typically form only ordinary phase-separated mixtures when blended or mixed with a polymer. The clays which are organically modified are more easily dispersed in the polymer matrix and can form a nanocomposite of two types: i.e. intercalated or exfoliated structures. It is preferable to utilize a clay with an exfoliated structure. Intercalated nanocomposites have polymer chains which are intercalated between the silicate layers of the clay resulting in a well ordered multilayer, where the layers of the clay retain their structural registry. Exfoliated nanocomposites are those in which the silicate clay layers or platelets having thickness on a nanometer scale, are exfoliated or separated, i.e. mechanically, by shear mixing, and are randomly and highly dispersed throughout the continuous polymer matrix. It is also possible that nanocomposites can be a mixture having both intercalated and exfoliated structures.
In order to obtain better compatibility between the polyolefin and organoclay, it is desirable that the organoclay contains substituted alkyl side chains.
The types of clay minerals which can be utilized include, but are not limited to, smectite, vermiculite, halloysite, or any synthetic analogs or combinations thereof, with smectite-type clay being preferred. Smectite-type clays which are useful in preparing the required organoclays include montmorillonite, hectorite, bentonite, beidellite, stevensite, saponite, nontronite, sauconite, sobokite, and svinfordite.
The preferred clays used to prepare the organophilic clay of this invention are cation-exchangeable smectite clays which have the cation exchange capacity of at least 75 miliequivalents per 100 grams of clay, 100 percent active basis (i.e. beneficiated and essentially free of non-clay impurities). Smectite-type clays are well known in science, geology and in the art of rheological additives, and are commercially available from a variety of sources both in the United States and throughout the world. They are unique among clays in that they exhibit the phenomena of swelling to many times their size when contacted with water.
The organic cations which can be reacted with a clay to form the organically modified clay utilized in the present invention and can be selected from a variety of nitrogen-based quaternary materials that are capable of exchanging cations with the selected smectite-type clay. The organic cations which are reacted with the smectite-type clay to prepare the inventive organophilic clays have a positive charge localized on a single nitrogen atom within the compound.
For this invention, the organic cation is provided by specific quaternary ammonium compounds derived in whole or in part from organic acid-derived esters. This organic cation is provided by a quaternary ammonium compound selected from the group consisting of the following formula:
wherein R1 is an alkyl or aralkyl-ester group having 8 to 30 carbon atoms as described below and R2, R3, and R4 are, independently, selected from groups such as (i) R1; (ii) linear or branched alkyl (including methyl), aliphatic, or aromatic groups having 1 to 30 carbon atoms (such groups can also include hydroxylaryl groups); (iii) aralkyl groups, such as benzyl and substituted benzyl moieties, including such groups having fused ring moieties having linear chains or branches of 1 to 30 carbon atoms; (iv) aryl groups such as phenyl and substituted phenyl including fused ring aromatic substituents; (v) beta, gamma-unsaturated groups having six or less carbon atoms or hydroxyalkyl groups having 2 to 6 carbon atoms; and (vi) hydrogen; M is an anion, typically chloride, methyl sulfate, acetate, iodide, and bromide. A further detailed description of organoclay compositions which are suitable for use in the present invention can be found in U.S. Pat. Nos. 5,718,841 and 4,434,075 which are fully incorporated herein by reference.
Suitable organoclays for use in the present invention are available from Southern Clay Products, of Gonzales, Tex., under the trademark Cloisite 15A, Cloisite 20A, and SCPXxe2x80x941967, from Nanocor, Inc. of Arlington Heights, Ill., tradename Nano #405, and from Rheox, Inc. (Elementis Specialties) of Hightstown, N.J., available as Rheox EA108, EA2827, EA2885, EA2886. Preferred organoclays are available from Rheox as EA2827 and EA2886.
The amount of organoclay utilized in the present invention generally is from about 2 to about 20 parts by weight, desirably, is from about 3 to about 15 parts by weight, and preferably is from about 4 to about 10 parts by weight per 100 parts by weight of polyolefin or polyolefin copolymers.
While the nanocomposite comprising a polyolefin polymer or copolymer and an organoclay has flame resistant or retardant properties and also does not sag or drip into a flame, thereby inhibiting it, the optional addition of other flame retardants to the composition can further enhance the performance of the nanocomposite compositions.
Flame retardants which can be utilized in the present invention include inorganic flame retardants such as but not limited to aluminum trihydroxide, magnesium oxide, magnesium hydroxide, alumina trihydrate, ammonium polyphosphide, antimony oxide, antimony trioxide, barium borate, calcium sulfate dihydrate, diammonium phosphate, magnesium carbonate, or borate based compounds, or combinations thereof. Preferred inorganic flame retardants of the present invention are magnesium hydroxide, alumina trihydrate and antimony oxide. The inorganic flame retardants of the present invention can be used in an amount generally from about 0 or 0.1 to about 50 parts by weight, desirably from about 1, 5, or 10 to about 35 parts, and preferably from about 15 to about 25 or 30 parts by weight per 100 parts by weight of polyolefin polymer or copolymer.
The present invention is substantially free of polar organic and/or halogenated organic flame retardants. That is, the present invention comprises generally less than 10 parts, desirably less than 5, 3, or 1 parts by weight per 100 parts by weight of polyolefins and preferably is completely free of polar organic and/or halogenated organic flame retardants. Examples include but are not limited to triphenyl phosphate, halogenated organic phosphate, chlorinated polyphosphate, chlorinated organic phosphate, chlorinated paraffin, brominated organics, and chlorinated organics. It is preferable to minimize use of halogenated flame retardants because when exposed to flame or ignition source, they tend to give off or emit toxic or noxious gases such as HCl gas or HBr gas which are also not environmentally friendly. Polar organic compounds are avoided because they have low weatherability, have poor process ability and tend to stick to processing rolls, and give off toxic gases when burned.
In addition to the above noted components, the present invention can contain various amounts of conventional processing aids, additives or ingredients. Such compounds include UV inhibitors, release agents, pigments such as carbon black and titanium dioxide, stabilizers, such as hindered phenols, antiozonates, phosphite and sulfides, and antioxidants. This list is merely an example of the potential additives and is by no means exhaustive. Such additives of the present invention can be used in effective amounts to achieve desired properties.
Any method which provides uniform mixing or dispersion between the organoclay with the polyolefin on a nanoscale or microscopic level can be used to prepare the compositions of this invention. Mechanical shearing methods can be employed such as single or twin screw extrusion, injection molding, Banbury type mixing, two-roll milling and the like. Shearing also can be achieved by introducing the polymer melt at one end of an extruder (single or double screw) and receiving the sheared polymer at the other end of the extruder. The temperature of the polymer melt, the length of the extruder, residence time of the melt in the extruder and the design of the extruder (single screw, twin screw, number of flights per unit length, channel depth, flight clearance, mixing zone, etc.) are several variables which control the amount of shear to be applied. It is important that the organoclays and polyolefins form a nanocomposite structure in order that the fire resistant or retardant properties of the compositions are maximized.
Preferably, the compositions of the present invention are processed into a sheet, film, membrane, or the like, or also formed into a multi-ply laminate or membrane.
A desirable method for forming sheeted compositions of the present invention is as follows: desired amounts of raw materials including the organoclay and polyolefins of the present invention are placed in a Banbury type mixer where they are mixed. The drop temperature of the Banbury is about 375xc2x0 F. Generally, the temperature of the compound is from about 400 to about 440xc2x0 F., and the mixing lasts for approximately 2 minutes and 20 seconds. The mixture is then transferred to two-roll mill, where the composition is milled and then further transferred to an extruder. The mixture is extruded through a die which preferably forms a rope or string-like extrudate, which can be put on a conveyor belt and transferred to a calender. The extrudate is then calendered to form the finished sheet material which generally has a thickness of from about 6 mils to about 50 mils, and preferably from about 18 mils to about 26 mils. Optionally, after the calendering step a backing and/or other layer or layers can be added or laminated to the flame retardant sheet thus forming a flame retardant laminate.
Another preferred method for preparing sheeted compositions of the present invention is as follows: the desired amounts of raw materials of the present invention are fed, preferably gravimetrically into an extruder, preferably a twin screw extruder and die extruded into a sheet or film. Optionally, the extrudate from the twin screw extruder can further be fed into a single extruder before being die formed into a sheet or film. The flame retardant sheet can be laminated with a backing, other layer or layers to form a flame retardant laminate.
A further desirable embodiment of the present invention includes forming a laminate including at least one flame retardant sheet of the present invention. While not being limited thereto, a three layer laminate is preferred. The flame retardant laminate generally comprises a top layer comprising a flame retardant sheet of the present invention, a middle layer generally comprises a reinforcing backing such as a woven or nonwoven polymer fabric layer such as polyester, nylon, etc., and a bottom layer which can be any suitable polymer layer such as but not limited to polyolefin polymers or copolymers as defined above, or a polyvinyl chloride layer. The laminates can be formed comprising at least one layer of the above noted flame retardant layer, a backing layer and a bottom or base layer as known by one of ordinary skill in the art. Generally, thicknesses of the at least three layer laminates range from about 20 to about 100 mils, desirably from about 30 to about 90 mils, and preferably from about 40 to about 70 mils.
The flame retardant sheets, laminates or membranes prepared from and according to the present invention are suitable for use where flame retardant properties are needed. Examples of suitable uses include but are not limited to films, laminates, wallcoverings, tents, tarps, and roofing membranes.
The National Highway Traffic Safety Administration standard, MVSS-302, specifies burn resistance standards for materials used in the occupant compartment of motor vehicles in order to reduce deaths and injuries to motor vehicle occupants caused by vehicle fires, especially those originating in the interior of the vehicle from sources such as matches or cigarettes. The MVSS-302 Standard states that a material xe2x80x9cshall not burn, nor transmit a flame front across its surface, at a rate of more than 4 inches per minute.xe2x80x9d The flame retardant sheets or films prepared for the present invention have burn rates generally less than 4 inches per minute, desirably less than 3.5 inches, or less than 3.0 inches per minute and preferably less than 2.5 inches per minute when tested according to MVSS-302. As can be seen by the following examples, the flame retardant membranes of the present invention offer excellent flame retardant and flame resistant properties, and can be extremely beneficial when employed in any of the above stated uses.
The present invention will be better understood by reference to the following examples, which serve to illustrate, but not limit the present invention.

Flame resistant polyolefin compositions containing organically modified clay