A sized staple fiber product that disperses quickly, thoroughly and uniformly in water is particularly useful in the manufacture of gypsum board by the slurry process. An aqueous chemical size composition on the surface of the fibers contains a high level of surfactant and can contain a polymer film former and a biocide. Preferably, the fiber is chopped glass fiber. Novel sizing composition and methods of making and using the fiber are also disclosed.

The invention involves a glass fiber having a chemical sizing applied on the surface to allow the fiber to disperse quickly and uniformly in plain water, the sizing composition and the methods of making and using the sized fiber.
Inorganic staple fiber including glass fiber, ceramic fiber and mineral fiber like mineral, glass or slag wool have been used extensively for reinforcing numerous materials and for enhancing the fire resistance of products. For example, glass fiber has been used to reinforce and enhance the fire resistance and rating of gypsum board.
At least two processes are typically used for adding glass fiber in the manufacture of gypsum board. The first process feeds dried glass fiber having a low moisture content and a chemical sizing on the fiber into wetted calcined gypsum, usually while the wetted material is being mixed and transported in an auger mixer. The fiber is dispersed in the mix by the mixing action. The second process involves adding the fiber directly into the water to make a slurry for a gypsum board before other ingredients are added. The water is typically a low quality, such as tap water, well water, lake or river water, i. e. plant water. The second process using low quality water is preferred by some manufacturers. For the second process, it is necessary that the fiber disperse quickly and uniformly. If it doesn""t, each cubic inch of the board won""t have enough fibers to pass the fire test and excess fiber will have to be used to insure enough fibers are in each portion of the board.
Unfortunately, the low moisture fiber made for feeding into the wetted gypsum mixture does not disperse uniformly and quickly necessitating that excess dry fiber be used or that a dispersant be added to the water prior to adding the fiber. Some dispersants found to work marginally in dispersing the dry fiber are flammable, presenting an undesirable risk to the manufacturing plants using the fiber.
Other glass fiber products are available in both dried and having a higher moisture content, both with a chemical sizing thereon depending on the intended application. Almost all glass fibers have a chemical sizing on their surface to protect the surface from abrasion and scratches during manufacture and use which will substantially reduce the strength of the fiber. The chemical sizing also can function to aid dispersion and to provide a better bond between the glass fiber and a matrix that the fiber will reinforce, such as a plastic material, a resin binder, etc.
Dry glass fiber products intended for use in plastics products will not disperse sufficiently in water and therefore are not suitable. Various wet chop fiber products, i. e. undried, chopped continuous glass fiber for use in making nonwoven mats in wet process machines or paper machines also did not disperse sufficiently. The sizing on these latter fiber products is designed to cause the fiber to disperse well in a xe2x80x9cwhitewaterxe2x80x9d and to bond well to a urea formaldehyde or acrylic resin binder and apparently for that reason do not separate well in plain water, i. e. water without one or more dispersants added. Whitewater used in wet process machines for making mats, unlike plain water in the gypsum board slurry process, contain various viscosity modifiers, defoaming agents, dispersants and other chemical additives that permit the fibers to disperse as desired.
Therefore, there is a need for a fiber product having a chemical sizing thereon that will permit the fiber to disperse quickly, adequately and uniformly in plant water.
The present invention includes a staple inorganic fiber having a chemical sizing, having a very high surfactant level on its surface. The fibers resulting are advantageous in any process where it is desired to disperse inorganic fiber in plant water. The invention also includes a size composition for inorganic fibers and a method of making a chopped inorganic fiber product for use in dispersing in plant water in a process for making a fiber reinforced product such as gypsum board. The term xe2x80x9cstaplexe2x80x9d includes fibers of various lengths under a few inches long. The fibers can all be of generally the same length or can be a mixture of lengths. For the present invention, lengths of less than 1.5 inches, such as one-half, one, three-fourths, one-quarter, etc. inch long are preferred. A length of one-half inch is particularly suitable for making gypsum board.
The novel size composition on the glass fiber comprises a plant water, deionized water, or distilled water, a high level of surfactant and preferably a film former polymer like polyvinyl alcohol, and can contain a biocide to retard microbial action. The surfactant is preferably a poly (Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl) Methyl-ammonio) Ethyl)-omega-Hydroxy-, N,Nxe2x80x2-Di(C 14-18 and C 16-18 unsaturated) Acyl Derivs., Me Sulfate (Salts). The sizing composition contains about 0.1-1.2 wt. percent surfactant, preferably about 0.3-0.9 wt. percent and most preferably about 0.6+/xe2x88x920.1 wt. percent. Other known surfactants compatible with water and known to act similarly to the family of surfactants mentioned just above can be used individually or in combination to replace all or a portion of the family of surfactants described just above.
The film former polymer is preferably present in amounts up to 1.5 wt. percent, preferably about 0.2-0.8 wt. percent and most preferably about 0.5+/xe2x88x920.1 wt. percent. All weight percentages of the sizing composition are based on the total weight of the sizing including water. When a biocide is used, it is present in effective amounts for this function and that can vary depending on the particular biocide chosen.
The fiber product can be dry or can contain up to about 25 percent moisture. Preferably the fibers are glass fibers chopped in lengths less than 1.5 inches, such as one-half, one, three-fourths, one-quarter, etc. inch long. The fibers can be of any suitable diameter, preferably between 5-23 micron. The fibers have a loss on ignition, due to the chemical sizing on their surfaces, of about 0.08-0.24 percent and preferably about 0.1-0.21 wt. percent and most preferably about 0.13-0.19 percent with a target of about 0.16 wt percent. The surfactant is at least about 30 wt. percent of the LOI and preferably at least 40 wt. percent up to as much as about 60 wt. percent with a film former making up the remainder with the exception of a minor, effective amount of a biocide. The fibers are made according to known processes, but using the inventive size composition to coat the fibers in place of conventional sizing compositions. The invention also includes the method of using the inventive fibers in processes for making fiber reinforced products where the fibers are dispersed in plant water as an early step in the process, such as a process for making gypsum board.
Chopped or staple inorganic fiber for use in reinforcements can be made using a number of different processes as is well known. The preferred process for making the preferred embodiment of the present invention which is a chopped sized glass fiber product is a well known process such as shown in U.S. Pat. Nos. 4,692,178, 4,194,896, and 3,869,268, the disclosures of which are incorporated herein by reference. Other processes for making mineral wool, staple glass or ceramic fibers having a chemical sizing on the longitudinal surfaces of the fibers would also be suitable. In the processes for making the preferred embodiments of the invention, which comprise continuously chopped fiber glass strands, glass fibers are pulled from fiberizers in a known way. A water mist is sprayed on the hot fibers to cool the fibers and then the fibers are pulled over a chemical sizing applicator where a chemical sizing, preferably an aqueous chemical sizing, is coated onto the fibers by bringing the fibers into contact with a curved surface having a layer of sizing thereon. The coated fibers are then pulled as a strand, usually along with several other strands of sized glass fibers, into a continuous chopper where the strands are chopped into desired lengths and discharged onto a conveyor, a dryer or into a package.
When it is desired to dry the fibers partially or completely, a vibrating fluid bed dryer like that shown in U.S. Pat. No. 4,840,755, or any suitable dryer, can be used. When it is desired to package the fibers without further drying, the discharged chopped fibers are discharged directly or indirectly into a plastic bag and sealed for shipment.
The fibers are preferably glass fibers and preferably E (electrical) and T (chemical resistant) glass fibers although other types of glass fibers including C, insulation glass, S, and R glass fibers are usable in the present invention. Any desired length is suitable; however, fiber to make gypsum board is preferably one-half inch long fibers. The chopped strands typically contain at least 2000 fibers each, but can contain substantially less and up to 4000 or more fibers. The diameter of the fibers can be any desired diameter within reason and usually the average fiber diameter is between 5 and 23 microns. Most typical products have fiber diameters of 16+/xe2x88x921 micron or 13+/1 micron, but the fiber diameter is not critical to the invention.
In practice, the sizing of the present invention is applied to the fibers according to one of the processes described above, or the aqueous sizing is sprayed onto the fibers while the fibers are suspended in the air in the known processes of applying binder to staple fibers for making fiber insulation products. The sizing is applied to the fibers in such concentrations to produce a fiber product having a loss on ignition (LOI) due to the chemical sizing in a range of 0.08-0.24 weight percent, based on the dry weight of the fiber product, preferably within a range of 0.11-0.21 wt. percent and most preferably 0.16+/xe2x88x920.03 wt. percent. The chemically sized fiber can be dried completely, but preferably the sized fiber is packaged wet with a moisture content in the range of about 5-25 wt. percent, preferably in the range of about 10-20 wt. percent and most preferably in the range of 15+/xe2x88x922 wt. percent.
The sizing composition of the present invention contains plant, deionized or distilled water, preferably plant water, a very level of surfactant, compared to conventional sizings for fibers, in an amount of about 0.1 to about 1.2 wt. percent, preferably about 0.3-0.9 wt percent, and most preferably about 0.5-0.7 wt. percent, based on the weight of a sizing batch. The surfactant is preferably a poly (Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl) Methyl-ammonio) Ethyl)-omega-Hydroxy-, N,Nxe2x80x2-Di(C 14-18 and C 16-18 unsaturated) Acyl Derivs., Me Sulfate (Salts) and most preferably is Varisoft(trademark) 222LT available from the Witco Corporation of Dublin, Ohio. Verisoft(trademark) SDC, available from the same company, is also suitable. The Varisoft(trademark) 222LT contains 80-95 percent of Methyl bis(Alkylamidoethyl) 2-Hydroxyethyl Ammonium Methyl Sulfate, Ethoxylated surfactant and 5-15 percent isoproponol, has an approximate specific gravity of 0.98 at 73 degrees F., a vapor pressure of 33 mm/Hg at 68 degrees F. and an NIT boiling point of 180 degrees F. at 760 mm Hg. Other known surfactants can be used, alone or in combination, to replace all or part of the specific surfactants described above. Such surfactants include glycols, fatty acid tallow amines like CAT-X(trademark), Aromox(trademark) DM-16 and DMHT and others, but the surfactant Varisoft(trademark) 222LT disperses optimally.
The sizing composition of the present invention can also contain a polymer film former, preferably a polymer film former like polyvinyl alcohol, a hydroxyethyl cellulose, a polyacrylamide or other known film former for fiber sizing in an amount in the range of 0 to about 1.5 wt. percent, preferably in the range of about 0.25-about 0.75 wt percent and most preferably about 0.4-0.06 wt. percent. The primary purpose of the film former is to protect the surface of the fiber, if necessary. Also, if the surfactant is used in a concentration near the high side of the acceptable range, a film former might not be needed in the sizing. However, due to the higher cost of the surfactant, and higher fiber processing cost at the higher levels, it is preferred to use a film former in the sizing composition in the above amounts.
A vinyl polymer film former such as for example polyvinyl alcohol is preferred and one preferred polyvinyl alcohol film former is available from Air Products and Chemicals, Inc. of Allentown, Pa. under the tradenames of Vinol(trademark) or AIRVOL(trademark) and most preferably is AIRVOL(trademark)205. Other known polyvinyl alcohol film formers for fiber sizing compositions may also be suitable.
When it is desired to protect the sizing in storage or on the fiber from bacterial or microbial activity, a biocide is included in the sizing in an effective amount for this function and the amount will vary depending on the particular biocide chosen. Preferably a biocide such as for example Chemtreat(trademark) CL 206 or CL 2150 is used, preferably in an amount of about 0.084 wt. percent, but other known biocides may also be used in effective amounts. Biocide may not be necessary if the sized fiber is dried or if the wet fiber is used within a short period of time or if an unpleasant aroma is not deemed a problem. If excessive bacterial action is allowed, the sizing may not perform satisfactorily. Preferably, a biocide is included to prevent bacterial action.
The amount of sizing on a fiber is determined by subjecting the fiber to the well known loss on ignition test, or xe2x80x9cLOIxe2x80x9d test. To accomplish an LOI test, a sample of sized fiber is weighed carefully and thoroughly dried and weighed again to determine the moisture content of the fiber, based on the dry weight of the fiber. The fiber is put into a furnace at a temperature exceeding 1000 degrees F. and having an air atmosphere to drive off all volatiles from the sizing and to burn off all organic materials in the sizing. Thereafter, the fibers are weighed again to determine the weight of the bare fibers. The difference between the dry weight and the bare fiber weight is then used to calculate the amount of dry sizing on the fibers, based on the weight of the bare fibers. Based on LOI, the resulting fiber product of the present invention has from about 0.08 to about 0.24 weight percent of dry sizing on the fiber, preferably about 0.12 to about 0.2 weight percent and most preferably about 0.16+/xe2x88x920.03 wt. percent. Of the dry sizing on the dry fiber, the cationic surfactant ingredient will preferably constitute at least about 30 wt. percent, preferably at least 40 or 45 wt. percent, up to about 60 wt. percent, and most preferably about 42-48 wt. percent. A film former will preferably be present and constitute at least about 20 wt. percent of the LOI, preferably about 35-50 wt. percent or more, and most preferably about 39-46 wt. percent. The fiber product of the present invention can be dry, but preferably is wet having a moisture content of about 5 to about 25 weight percent, preferably about 15+/xe2x88x922 wt. percent.
When the fiber product of the present invention is added, such as by dumping or feeding slowly, to plain plant water, containing no dispersants, the fiber quickly disperses thoroughly and uniformly as desired and in a substantially different and superior degree compared with previous staple glass fiber products. This is very useful in any process where it is desirable to disperse fiber in plant water. The present fiber product is particularly useful in the process of making gypsum board in a processes like that disclosed in U.S. Pat. No. 4,241,136, the disclosure of which is incorporated herein by reference, and other similar processes of making gypsum board where early in the process the fiber is added to plant water.


A process for the continuous preparation of a thermoplastic molding composition with narrow scatter of the melt flow index, which comprises mixing two or more chemically identical starting materials of different melt flow index in a pelletizing extruder fitted with an on-line melt flow index meter and adjustable metering systems.

The invention relates to a process for the preparation of a thermoplastic molding composition with narrow scatter of the melt flow index.
Thermoplastics are processed predominantly by injection molding or extrusion. In these methods, the material is melted, and the melt is forced continuously or discontinuously into molds, in which the material resolidifies. This allows very large numbers of identical moldings to be produced. However, it is a prerequisite for this type of processing that the polymer melt has a certain viscosity with the smallest possible variation, since variations in the melt viscosity within a material delivery intended for processing can result in break downs and an increased reject rate.
All producers of raw materials therefore offer their products in various melt viscosity grades. These products are in each case identical in chemical makeup and in the composition of the stabilizer and additive mixtures. The difference between the individual product grades is then exclusively the melt viscosity. Examples of this are indicated in the producers product brochures.
The measure of the melt viscosity that is usually indicated is the volume flow rate in accordance with ISO 1133 in ml/10 min. However, the mass flow rate in g/10 min is also often used.
In order to produce a defined melt flow index of a polymer, the mixture of one or more monomers and initiators is usually admixed, during polymer synthesis, with substances which result in chain growth termination and in turn initiate a new chain. The use of these substances, known as xe2x80x9cregulatorsxe2x80x9d, allows the mean molar mass to be adjusted. However, this method is imprecise and gives products with considerable scatter in the melt viscosity. The melt flow index reproducibility which is necessary for commercial use of the polymer can only be achieved with considerable effort. In continuous polymer syntheses in particular, the effort needed to regulate the melt flow index is very high.
In the copolymerization of trioxane with cyclic ethers and cyclic acetals to give polyoxymethylene, low-molecular-weight, open-chain acetals, such as methylal or butylaln are usually used as regulators. In spite of the use of these substances, the resultant products exhibit, however, considerable variation in the melt flow index. However, variations in the melt flow index can, as mentioned above, result in production problems during processing of the material by injection molding or extrusion. In order to reduce the scatter in the melt flow index, homogenization devices are therefore usually used after granulation. In this additional processing step, material is mixed until low scatter of the melt flow index has been achieved over the entire product volume. However, this additional effort is associated with considerable costs.
Mixtures of polyoxymethylene components of high and low melt flow index which have improved flow properties are known (JP-A-50-030 949 and JP-A-05-279 551). These can be homopolymers or copolymers. However, each of the examples indicates only the resultant melt flow index of a mixture prepared discontinuously, i.e. batchwise; the range of variation in the values for mixtures prepared repeatedly cannot be derived from the prior art. There was therefore a need to avoid the disadvantages of the prior art.
The object has been achieved by a continuous process for the preparation of a thermoplastic molding composition with low scatter of the melt flow index, in which two or more chemically identical starting materials of different melt flow index are mixed in a pelletizing extruder equipped with an on-line melt flow index meter and adjustable metering systems.
Suitable thermoplastic molding compositions for use in the process of the invention are known homopolymers and copolymers of polyoxymethylene (POM), polyesters, such as polyethylene terephthalate and polybutylene terephthalate, and polyamide, preferably POM.
The process of the invention allows the melt flow index of, for example, linear POM polymers to be set significantly more accurately than is the case in the synthesis of the monomers using regulators. Neither do the mechanical properties of the products prepared by mixing in accordance with the invention differ from the properties of the products of the same melt flow index prepared by synthesis using regulators. However, the mixing process of the invention, starting from two or more products of different melt flow index, allows any melt flow index value between the starting values to be produced within narrow limits by varying the respective proportions by weight.
This process is highly suitable for automation and for large-scale production. For this purpose, the pelletizing extruder is equipped with an on-line melt flow index meter and adjustable metering systems, in each case known pieces of equipment. Manufacturers of suitable on-line meters are Gottfert, Buchen, Germany, and Reametrix, German subsidiary, Frankfurt am Main, Germany. Suitable metering systems can be purchased, for example, from Engelhart, Germany, or K-tron-Soder, Switzerland. Electronic regulators which can be used are, for example, Sipart DR 22, Siemens AG, Karlsruhe, Germany. The melt flow index meter measurement signal, which has the value of the target product, controls the metering of the material streams of the individual components in such a way that the measurement signal remains constant at the specified target value. This allows the preparation of products which, as stated above, have only minimal variations within either the individual batches or in continuous operation. In addition, it is possible to produce any desired melt flow indices for specific applications in a targeted manner and with low scatter of the flow behavior. The melt flow indices of the starting substances used for the mixture can vary within broad limits. The dispensation with complex, accurate melt flow index regulation that this allows during the polymer synthesis enables considerable cost savings to be made in the provision of the starting substances for preparation of the end product.
The products obtained in accordance with the invention can be processed without problems, since the properties do not change compared with products prepared in a conventional manner. It is advantageous that no variations occur in the melt viscosities and consequently no breakdowns or rejects are observed in processing by injection molding or extrusion.

Method for producing thermoplastic synthetic moulding compounds


An aggregate chamber for leaching effluent comprises a chamber cavity, at least one panel positioned along a periphery of the chamber cavity, and aggregate for filtering effluent. The chamber unit may include a plurality of foldingly connected panels, and at least one conduit for delivering effluent. A leach line comprises a trench excavated in a leach field, and a plurality of chamber units having a cavity, at least one panel, and aggregate for filtering effluent. A leach field comprises a source of effluent, a plurality of trenches excavated in the soil adjacent the source of effluent, and a plurality of leach lines positioned in the plurality of trenches in fluid connection with the source of effluent, each leach line having at least one chamber unit comprising a cavity, at least one panel, and an aggregate for filtering effluent. A method aspect of the invention includes leaching effluent by conducting effluent from a source to a chamber, filtering the effluent through an aggregate, and leaching the effluent into the leach field. A method of constructing a leach field comprises excavating a plurality of trenches, positioning a plurality of panels in the trenches to define a plurality of walls for chamber leach lines, positioning aggregate adjacent the plurality of panels for substantially filtering the effluent leaching into the field, and connecting the aggregate chamber leach lines to a source of effluent.

The present invention relates to drainage field systems and, more particularly, to chamber leach line systems which are manufactured and ready to install in a drainage field for wastewater and stormwater.
Residential septic tank systems are used where municipal sewerage systems are not available. Wastewater from the home flows into the septic tank for on-site treatment through the biological activity of microorganisms, and leachate passing from the septic tank flows into a drain field from which it percolates into the ground. Drain fields of standard construction include a network of trenches dug in the ground, with a layer of loose aggregate material, such as gravel, placed in the bottom of the trench. A pipe is connected to the outlet of the septic tank and also connected to perforated pipes which are laid into the network of trenches. The space between the perforated pipe and the ground, which is filled by the loose aggregate, essentially becomes a drainage cavity for receiving leachate discharged through the perforations in the pipe. In normal operation, the septic tank effluent flows out into the network of perforated pipes and slowly percolates through the aggregate in the bottom of the trenches and down through the soil. Standard systems such as the one described are not well adapted for handling peak flows, such as might be experienced when several high volume water consumption activities are occurring simultaneously in the house, or when the leaching field is intended to handle stormwater.
Chamber-type drainage systems are able to handle larger flows and have become more widely used as an improvement over standard systems. A chamber system includes a void space into which excess effluent can flow for holding prior to percolation through the ground. The chambers are generally buried in a network of trenches as part of the leach field system. Chamber systems thus provide the advantage of being able to accommodate larger peak flows of effluent than standard systems. Examples of such chamber systems include U.S. Pat. No. 5,511,903 to Nichols et al., U.S. Pat. No. 5,498,104 to Gray, U.S. Pat. No. 5,017,041 to Nichols, and U.S. Pat. No. 4,759,661 to Nichols et al. Even though chamber systems accommodate larger peak flows, however, leaching chambers systems have not achieved the soil interface characteristics offered by conventional trench and gravel installations.
With the foregoing in mind, the present invention advantageously provides a chamber unit for leaching effluent in a leach field. An embodiment of the chamber unit comprises a chamber cavity for therein receiving effluent for leaching, at least one panel positioned to define a periphery of the chamber cavity, and aggregate comprising a plurality of bodies positioned adjacent the panel for filtering effluent. The aggregate may be conventional gravel but is preferably a lightweight particulate material such as expanded polystyrene, polyethylene, polyurethane, polypropylene, and rubber chips such as obtained from ground up tires.
In a preferred embodiment of the invention chamber units are fluidly connected together and to a source of effluent to thereby form a chamber leach line. A sufficient number of leach lines is then positioned in trenches excavated in soil to form a leach field. A chamber unit may be connected to a source of effluent so as to receive effluent directly into the chamber cavity. The soil floor of the excavated trench generally forms the lower periphery of the chamber leach line, through which effluent filters into the soil. It is known that the soil surface through which effluent filters will generally develop a film of microbial growth, a biofilm which may eventually clog the soil surface. Advantageously, aggregate may be positioned relative to the chamber unit cavity so as to filter effluent flowing out of the chamber cavity and into the surrounding soil of the trench. The aggregate material provides a greatly increased surface area for biofilm accumulation, which in turn serves for enhancing microbial treatment of the effluent to thereby reduce nutrients leaching into the soil.
A further embodiment positions aggregate along side peripheries of the chamber cavity, so that effluent is filtered through the aggregate as it flows laterally out of the chamber cavity and into the surrounding soil. Aggregate, however, may also be positioned along a lower periphery of the chamber cavity to provide filtration for effluent flowing downwardly from the cavity into the soil of the trench. Aggregate positioned along side peripheries of the chamber cavity is preferably contained in a sleeve of water permeable material, and may be thus prefabricated prior to field installation. Under normal flow conditions, effluent generally flows into the surrounding soil through the lower periphery of the chamber cavity. Under excess flow conditions, however, where the soil underlying the chamber cavity is unable to absorb the volume, effluent will also flow laterally into the surrounding soil through side peripheries of the chamber cavity, thereby being filtered through the aggregate.
In another embodiment, side peripheries of the chamber cavity are defined by perforated conduit connected to a source of effluent so that the effluent passes through the conduit and trickles into the chamber cavity from the perforated conduit. This embodiment may have aggregate positioned adjacent the perforated conduit so as to filter effluent trickling from the conduit into the chamber cavity.
In yet another embodiment the chamber unit includes a plurality of foldingly connected, substantially flat panels positioned to define peripheries of a chamber cavity when properly positioned unfolded in a trench excavated in a leach field. This embodiment includes at least one conduit positioned to deliver effluent to the chamber cavity. Prefabrication of the chamber unit as a plurality of connected substantially flat panels which advantageously fold along the connections for allowing easy storage and transportation of the units in a folded position. Additionally, the individual units are easily set up by unfolding and properly positioning within trenches to thereby form chamber leach lines when connected together.
The invention further includes a leach field for leaching effluent into soil. The leach field comprises a source of effluent, a plurality of trenches excavated in soil adjacent the source of effluent, and a plurality of leach lines positioned in the plurality of trenches in fluid connection with the source of effluent for distributing the effluent by leaching into the soil. Each leach line of the plurality includes at least one chamber unit comprising a cavity for therein receiving the effluent for leaching, at least one panel positioned along a periphery of the cavity, and an aggregate comprising a plurality of bodies positioned adjacent the panel for filtering effluent.
A method aspect of the invention includes leaching effluent into a leach field by conducting effluent from a source of effluent to a chamber for holding prior to leaching, filtering the effluent through an aggregate as the effluent flows from the chamber, and leaching the effluent into the leach field after filtering through the aggregate. A further embodiment of the method comprises conducting effluent from a source of effluent, filtering the effluent while the effluent flows into a chamber for holding prior to leaching, and leaching the effluent from the chamber into the leach field.
The invention additionally includes a method of constructing a leach field for effluent. This method comprises excavating a plurality of trenches in soil, positioning a plurality of panels in the trenches so as to define a plurality of walls for chamber leach lines, positioning aggregate adjacent the plurality of panels for substantially filtering the effluent leaching into the field, and connecting the aggregate chamber leach lines to a source of effluent.

Aggregate chamber leach lines for leaching effluent and associated method


An improved bit assembly for road milling, mining, and trenching equipment includes a streamlined tip assembly that is a combination of conical and cylindrical in shape and devoid of protrusions or annular indentations that might impede the flow of removed material over and around the bit assembly or provide space for removed material to become clogged or imbedded on the tip assembly. The generally cylindrical hollow shank that mounts the bit holder to the bit block includes at least one axially aligned slot along its side wall that allows the side wall to supply radial force to maintain the bit holder in the bit block.

Bit assemblies are utilized in road, off-road and mining machinery on the perimeter and across the width of a rotary drum or on the outside of a continuous chain or the like where the bits are moved through an orbit which is intercepted by the face of the material being removed or recycled. Road milling equipment removes the defective surface of a road and smoothes the top of all or selected portions of the road surface. The bits utilized include a tip and a shank. The shank is received and may axially rotate in a bit holder which is secured onto a bit block that, in turn, is mounted on the drum. Each of the bits has a hardened tip, preferably made of tungsten carbide or such other hardened material that acts to remove a portion of the surface it contacts. By using a sufficient number of these bits around the outer surface of a rotating drum, a large amount of surface may be worked.
The bit assembly including the bit, bit holder and bit block, act on the portion of the surface it is removing to separate that surface from the underlayment and as the drum rotates, passed that surface over the outside of the bit assembly. The milling of concrete and macadam surfaces required a substantial power output to operate the drum or continuous chain or the like. With the use of such a substantial power output to operate the heavy milling machinery, a need has developed to provide a more efficient bit assembly that utilizes less power to perform the same function as machines fitted with prior art bit assemblies.
In O'Neill et al, U.S. Pat. No. 4,915,455, a substantially frustoconical bit is mounted upon a block that provides a large mostly flat forward leading surface that impedes the flow of macadam or concrete therearound and provides a barrier to movement of the bit on additional portions of the surface to be milled.
Additionally, a need has developed for providing ease of removability of bit holders in their bit blocks, especially when portions of or all of the assembly becomes worn and in need of replacement. U.S. Pat. No. 5,374,111 discloses an undercut flange at the bottom of a base of a bit that allows a pry bar to be wedged between that flange and the top of the bit block to help remove a bit from the bit block. It would be desirable to provide more efficient means and multiple means for allowing the removal of a bit holder from a bit block. Additionally, heretofore known bit holders have been retained in bit blocks by the use of threaded nuts or retainer rings. A need has developed to provide means to mount the shank portion of a bit holder in a bit block without the need of a fastener on the distal end of the bit holder shank to retain same in the bit block.
Further, a need has developed for a truly quick-change type of bit holder that may easily and quickly be inserted in the bit block and removed therefrom.
It is, therefore, an object of the present invention, generally stated, to provide an improved means for quickly mounting and/or removing a bit holder from its associated bit block.
Another object of the present invention is the provision of a more efficient bit assembly that requires less power to run when mounted on road milling equipment than heretofore known bit assemblies while providing longer lasting useful life of operation.
A further object of the present invention is the provision of multiple means for retaining a bit holder in a bit block by means of a resilient interference fit between the holder and the block.
Another object of the present invention is the provision of an easily mounted tool on the bit holder that facilitates the removal of the bit holder from the bit block at the front of the leading surface of the bit holder without the need for a large amount of access to the rear of the bit block.
Referring to FIG. 1, a bit, bit holder and bit block assembly, generally indicated at 15, constructed in accordance with the present invention, includes a bit, generally indicated at 16 and a spacer, generally indicated at 17, together with a bit holder, generally indicated at 18 and a bit block, generally indicated at 20.
The bit 16 includes a hardened tip 21, usually made of tungsten carbide. The base of tungsten carbide tip 21 (not shown) resides in a pocket (not shown) in the front face 22 of a frustoconical forward portion 23 of bit 16. At the rear of the frustoconical portion 23 is a cylindrical front portion base 24. In this embodiment, the cylindrical base 24 performs a function which is analogous to prior art known as a "tire portion" of the bit because in that prior art the outside of the base portion has a rounded shape similar to the outside of a donut or tire. Aft of the cylindrical base 24, the tip narrows to a cylindrical shank 25, which, in this embodiment, includes a C-shaped retainer 26 therearound and a cylindrical shank portion base 27 defining the rear end of the bit.
The spacer 17 is shaped similarly to the shank portion 25-27 of bit 16 in that it includes opposed cylindrical ends 28, 30 and a slightly narrowed cylindrical shank portion 31 mounted therebetween having a C-shaped retainer 32 positioned therearound. At the outside of the opposed cylindrical end 30 is a spherical indent 33 whose purpose will be discussed in more detail below.
In this embodiment of the present invention, the bit holder, generally indicated at 18, is termed a bulbous shaped bit holder as the front generally conical portion includes a middle section having a convex outline. The leading portion of the generally conical front section of bit holder 18 includes a cylindrical nose 34, having a flat annular face 35 from which a central bore 36 extends axially all the way through the bit holder. A plurality of notches 37-37 (one shown) adjacent the front face 35 of the bit holder, provide an access area to the cylindrical base 24 of the tip 16 into which a prying tool may be positioned to force out the base 24 of the bit 16 when the bit shank 25 and spacer 17 are mounted in the bore 36 of the bit holder 18. Rearwardly adjacent the nose 34 is the bulbous portion 38 of the generally frustoconical front section of the bit holder 18. Rearwardly of the bulbous section 38 is the cylindrical base 40 which performs a similar function in the bit holder 18 that the cylindrical base 24 performs in the bit 16.
Aft of the base 40 of the conical front portion of bit holder 18 is the shank 41. The shank portion 41 includes an upper shoulder 42 which is slightly larger diameter than the middle shank portion 41, and a second enlarged portion 42a of shank 41 immediately adjacent the distal end 43 thereof. A slot, whose forward end is indicated at 44 extends from the end of upper shoulder portion 42 through the distal end 43 of the shank 41 thus providing a C-shape for the perimeter of the shank 41 allowing it to expand and contract diametrically for a force fit into the bit block, generally indicated at 20. A pin 45 is mounted in a bore 46 180 degrees around shank 41 from the slot 44. The pin 45 assures that the spacer 17 will not fall out of the bottom of bit holder bore 36 in the bit holder 18 when it is mounted therein.
In another important aspect of the present invention, the bit block 20 includes a base mounting portion 47 having a base 48 which is mountable on the outside of a drum (not shown) which is a part of road milling equipment. The front or leading portion of the mounting section 47 includes a pair of rearwardly angled shoulders 50-50 (only one shown). Adjacent the mounting section 47 which holds the bit block on the drum is a generally annular cylindrical bit holder mounting portion 51 having a central bore 52 positioned therethrough from a top surface 53 to a bottom distal portion 54 of the bit block 20. Adjacent the bottom portion 54 and opposite the mounting portion 47 is a slot 55 which increases the accessibility of a tool to the rear of the bit block and into the bore 52 of the bit block 20 at the rear 54 thereof. Also, immediately above slot 55 is a cylindrical bore 56 which may have a pin (shown in FIGS. 3 and 5 at 56a). Pin 56a extends into the slot 44 of the bit holder, thus preventing rotation of same when mounted in the bit block. As is evident from the exploded view, the shank portion 41 of the bit holder 18 is press fit into the bore 52 of the bit block 20 and retained therein. Further, the spacer 17 and the shank portion 25 of bit 16 are mountable through the front end 35 of the bit holder 18 and are retained therein by C-shaped retainers 26 and 32. Additionally, the spacer is retained in its mounted position by pin 45.
Referring to FIG. 2, the mounting relation between the bit block 20, bit holder 18, spacer 17 and bit 16 is shown in cross section. FIG. 2 is modified from a straight cross section of the assembly as shown in FIG. 1 in that the slot 44 of bit holder 18 and the slot 55 of bit block 20 are not seen so that the mounting relation between the bit block and bit holder may be shown in more detail. Additionally, the upper shoulder 42 of the bit holder is not shown so that the relationship between the lower shoulder 42a and the bit block bore 52 may be shown.
As is shown most clearly in FIG. 2, the lower raised shoulder 42a of the shank portion 41 of the bit holder 18 is press fit into the bore 52 of bit block 20. The press fit between the two is on the order of four times the ordinary press fit between a cylindrical male member and an annular bore because the C-shape cross section of the shank is resilient with the addition of slot 44 therein. This allows the lower shoulder 42a to be positioned in bore 52 with such a substantial press fit that neither a retaining nut nor retaining ring is necessary to maintain the bit holder in the bit block. However, because of vibration and potential rotation of the bit holder in the bit block, a pin 56a (FIG. 5) is mounted through bore 56 into the slot 44 (FIG. 1) of the bit holder shank in order to maintain the bit holder and bit block in correct non-rotating mounted orientation. As additionally shown in FIG. 2, the bit 16 and spacer 17 are mounted in the central bore 36 of bit holder 18 and retained therein by C-shaped retainer clips 26 and 32. As shown most clearly in FIG. 2, the semi-cylindrical indent 33 in the spacer 17 provides for the insertion of a tool through the backside of bore 36 which will accommodate punching out the spacer 17 and the bit 16 from the back of the assembly.
As also shown most clearly in FIG. 2, in an important aspect of the present invention, the profile of the bit, bit holder and bit block maintains either a cylindrical outline or a conical outline although the conical outline may be slightly concave or convex also, to provide a smooth efficient aerodynamic outer surface which in this case does not have air passing by it, but has macadam or concrete passing by it. This smooth outer surface of the bit 16, bit holder 18 and bit block 20 also benefits from the opposed shoulders 50 at the leading surface of the bit block 20. The aim in providing this efficient aerodynamic profile is to both provide longer life for the assembly and the portions thereof, and to provide for more efficient separation of the macadam or concrete and passage of same by the assembly, thus requiring less power to run the road milling equipment and also providing longer life for the assembly 15 when performing its function. Generally, the lack of sharp edges and the lack of cylindrical outcroppings along the surface, or indents along the surface, provide fewer areas for macadam or concrete to sharply impact the surface or become imbedded thereon, thus assuring a more efficient and longer work life for the assembly 15 and the parts thereof.
In operation, prior art road milling bit, bit holder and bit block assemblies normally operate for between three and four hundred hours before the parts wear out or a failure occurs in at least one part of the assembly. Applicant's bit, bit holder and bit block assembly have been operated for more than 1000 hours without serious deterioration of the assembly or failure of parts thereof. Also, the use of the assembly 15 of the present invention on road milling equipment has provided a milling system which consumes less gasoline per hour to operate. While gas consumption of the road milling equipment varies depending on depth of cut, temperature, surface to be milled, etc., over a long period of time, it is believed that the bit assembly of the invention yields about a 10 percent improvement over prior art bit assemblies.
Referring to FIGS. 3-6, a second embodiment of the present invention is shown utilizing the bit block 20 of the first embodiment together with a concave style bit holder, generally indicated at 60. Bit holder 60 differs from bit holder 18 not only in that it is concave in its conical leading portion, but also because it has a hardened annular insert 61 preferably made of tungsten carbide positioned at its leading surface. Since the hardened insert 61 extends towards the outside of the concave, but generally conical forward surface 62 of the front portion of bit holder 60 to provide structural strength, there are no notches in the concave surface 62. With this embodiment, the bit 16 (not shown) would be driven out of the bit holder 60 for replacement by inserting a rod to tool (not shown) in the bottom of bore 63 of the bit holder (shown most clearly in FIG. 3) until it is stopped by semi-spherical indent 33 of spacer 17 (FIG. 2) where a hammer struck on the end of the tool will drive the bit 16 outwardly of the bit holder 60. The use of a hardened insert 61 has been shown to increase the work life of the bit holder 60 by providing a tougher mounting for the bit 16 in the bit holder 60.
FIGS. 4 and 6 tend to show the increased efficiency obtained by utilizing opposed shoulders 50-50 to direct macadam away from the forward portion 50a and third shoulder 50b of the bit block mounting portion. Also, as mentioned previously, and shown in FIGS. 3 and 5, the pin 56a is aligned with the slot 64 in the shank of bit holder 60 to prevent rotation of the bit holder 60 in the bit block 20 when mounted therein. Additionally, FIG. 3 shows the accessibility of the shank 65 on bit holder 60 through the rear 54 of the bit block 20. Shown most clearly in FIGS. 3-6, the forward facing surfaces of the bit holder 60 and bit block 20, with the exception of leading surface 50a for strength of part reasons, all extend rearwardly and outwardly to provide a smooth, efficient deflecting surface for material separated from the macadam or concrete by the bit 16.
Referring to FIGS. 7, 8 and 9, a third embodiment of a bit holder is shown generally at 70. Bit holder 70 is similar to the bit holder 18 in that it is a steel front bulbous type having a slotted shank. The steel cylindrical flange front 71 includes an annular steel face 72 similar to the first embodiment. The bulbous frustoconical portion 73 extends rearwardly beyond the cylindrical nose and includes a pair of notches 74, 75 therein that provide tool access to the back of a bit for easing removal of the bit from the bit holder.
At the rear of the bulbous frustoconical portion 73 is the cylindrical base 76. In one important aspect of the present invention, the base 76 includes a rectangular notch 77 that extends radially inwardly from the outside of the circumference of cylindrical base 76 and is also in communication with the back face 76a of the cylindrical base. When the bit holder 70 is mounted in the bit block, such as 20, notch 77 will allow access of a tool therein to provide a prying method for removing the bit holder from the bit block. This is especially important if, for some reason, access to the back of the bit holder is not obtainable. A prying tool positioned in notch 77 would provide for removal of the bit holder out of the bit block until after the upper shoulder 78 of shank portion 79 is free of the top of the bit block, thus easing removal of the bit holder from the bit block.
Referring to FIGS. 10 and 11, a fourth embodiment of the bit holder of the present invention, generally indicated at 80 is a steel nosed bit holder similar to that shown in FIG. 1, i.e., a bulbous style frustoconical nose bit holder, with the exception that the notches 82, 83 are round in outline rather than rectangular as shown in the first embodiment 18. The frustoconical portion at the front of the bit holder 80 includes the cylindrical nose 84, bulbous frustoconical portion 85 and cylindrical base 86. Rearwardly of the base, the shank portion 87 includes an upper shoulder 88 similar to that shown in the first embodiment. However, the remainder of shank 87 differs from the shank 41 of the first embodiment in two ways. First, instead of having a slot extending from the edge of upper shoulder 88 to the distal end 89 of the shank, the fourth embodiment of the present invention includes a pair of diametrically opposed slots 90-90a from the upper shoulder 88 to the forward edge of the distal end 89 such that the distal end 89 is still annular in shape rather than C-shaped as in the first embodiment 18. The second difference in the shank portion between the first embodiment and the fourth embodiment is that the lower shoulder portion 91 is moved forwardly on the shank to be at a position to bisect the opposed slots 90-90a. In this embodiment, the pair of opposed slots take away stiffness from the annular shank such that the lower shoulder portions 91 are resilient similar to the lower shoulder portion 42a of the first embodiment even though the distal end 89 of the shank is continuously circular or annular in shape. The press fit of the lower shoulder 91 in the bore 52 of the bit block 20 is similar to that of the lower shoulder 42a of the bit holder 18 in that it is a greater interference fit than that found in typical male-female member press fits, thus providing for ease of secure mountability of the bit holder 80 in the bore 52 of bit block 20. As with the other embodiments, no nut or retainer is necessary to hold the bit holder in the bit block. Also, pin 56a fits in either of the slots 90-90a.
Referring to FIG. 12, a tool for aiding removal of the bit holder 18 from the bit block 20 is generally indicated at 95. Tool 95 includes an elongate bolt 98 having a hex head 96, a shank 100 that extends through the bore 36 (FIG. 1) of the bit holder 18 and out the distal end 43 thereof where a hex head nut 99 may be turned on the threads at the distal end of the shank portion 100 of bolt 98. An enlarged radially extending flange 101 has a central bore 102 through which the bolt shank 100 is passed prior to inserting the bolt through the bit holder bore 36 (FIG. 1). The large flat surface 101 on the rearward side of annular flange 101 provides ample room for positioning the tool thereagainst or striking a hammer thereto to remove the bit holder 18 from the bit block 20 without needing a large amount of access to the rear of the bit block 20 other than room to fit nut 99.
Referring to FIG. 13, a second embodiment of spacer or plunger, generally indicated at 105, performs the same function as spacer 17, is cylindrical in outline and slidingly fits in the central bore 106 of bit holder 107. Spacer of plunger 105 includes an elongate infernal slot 108 extending mediate the front end 110 and rear cupped end 111 thereof. A perpendicular bore 112 radially through the shank sidewall 113 secures a pin 114 that extends into slot 108 to limit the movement of the spacer in the bore. An additional notch 115 in spacer 105 provides for removing the spacer from the bit holder 107 by driving the pin into the notch. Unlike spacer 17, spacer 105 does not need a retainer 32 to keep it mounted in its respective bit holder bore. Thus, an improved road milling bit assembly spacer, bit holder and bit block have been shown and described together with three additional embodiments of the bit holder and a bit holder removing tool. The bit assembly in being efficiently smooth and lacking in substantial annular discontinuities around the bit provides an efficiency of use when the bit separates either macadam or concrete and also provides for an efficient passage of such material around the bit assembly that lessens wear on the assembly and requires less power to drive the assembly through the macadam or concrete while also providing greater bit assembly life and requiring less fuel per hour to drive the assembly than heretofore known bit assemblies.
While five differing embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. It is the intent of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.

Bit assemblies for road milling, mining and trenching equipment


A visor assembly having a lower wall member, an upper wall member, a lid member, a living hinge and a partition member. The living hinge pivotably couples the lid member to the upper wall member. The partition member cooperates with the lower and upper wall members to form a storage compartment. The living hinge permits the lid member to be pivotably moved between a first position in which the lid member substantially clears the storage compartment parallel and a second position in which the lid member substantially covers the storage compartment.

1. Technical Field
The present invention relates generally to vehicle visors and more particularly to a visor having an integrally formed covered storage compartment.
2. Discussion
It has long been recognized that the visor of a vehicle is a convenient location for the storage of small personal articles, such as sunglasses and the like. Typically, visors have been provided with pockets, flaps or trays mounted thereon for receiving such articles. This approach is typically used in the prior art to provide attachments to the upholstered surface of the visors. When such prior art includes an opening flap or tray, they typically open in a downward direction which tends to obstruct the view of the vehicle operator.
One device proposed to overcome the drawbacks of the prior art is disclosed in U.S. Pat. No. 4,275,916 entitled xe2x80x9cVisor With Storage Compartmentxe2x80x9d, the disclosure of which is hereby incorporated by reference as if fully set forth herein. This device includes a visor body having a generally rectangular recess that is adapted to receive a covered storage compartment assembly. The covered storage compartment assembly includes a frame, a cover and numerous small components such as springs, which must be assembled together prior to installing the covered storage compartment to a visor body. The use of numerous additional components and the requirement for labor to subassemble and install the covered storage compartment may add considerable cost to a visor assembly. Accordingly, there is a need in the art for a visor with a covered storage compartment that may be more easily and cost-effectively produced.
It is one object of the present invention to provide a visor assembly with a covered storage compartment which can be produced at a relatively lower cost.
It is another object of the present invention to provide a visor assembly with a covered storage compartment with a lid member that is unitarily formed with a body structure of the visor.
In one preferred form, the present invention provides a visor assembly having a lower wall member, an upper wall member, a lid member, a living hinge and a partition member. The living hinge pivotably couples the lid member to the upper wall member. The partition member cooperates with the lower and upper wall members to form a storage compartment. The living hinge permits the lid member to be pivotably moved between a first position in which the lid member substantially clears the storage compartment parallel and a second position in which the lid member substantially covers the storage compartment.


An abrasive dentifrice composition which effects enhanced tooth and stain removal which comprises an orally acceptable vehicle containing a combination of a low oil absorption silica abrasive having an oil absorption value of less than 100 cc/100 g silica and an proteolytic enzyme.

1. Field of the Invention
This invention relates generally to oral compositions for removing tooth stains, and more particularly, to enzyme enhanced silica abrasive containing dental compositions effecting stain removal from teeth.
2. The Prior Art
Many substances that a person confronts or comes in contact with on a daily basis can xe2x80x9cstainxe2x80x9d one""s teeth. In particular, foods, and fluids such as tea and coffee that one consumes tend to stain one""s teeth. These products or substances tend to accumulate on the enamel layer of the tooth and form a pellicle film over the teeth. These staining and discoloring substances can then permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one""s teeth.
Synthetically produced silicas incorporated in dentifrice compositions act as an abrasive to debride and physically scrub the external surface of the teeth. This scrubbing action removes the organic film (i.e. the pellicle), formed of salivary proteins which covers the teeth and which become stained and discolored. Such physical removal of the stained pellicle is a simple and effective means of removing the undesirable surface staining and discoloration which occurs daily.
Synthetic silicas useful as dentifrice abrasives include both silica gels and precipitated silicas which are prepared by the neutralization of aqueous silicate solutions with a strong mineral acid. In the preparation of silica gel, a silica hydrogel is formed which is then typically washed to a low salt content. The washed hydrogel may be milled to the desired size, or otherwise dried, ultimately to the point where its structure no longer changes as a result of shrinkage. When preparing such synthetic silicas, the objective is to obtain abrasives which provide maximal cleaning (i.e. removal of stained pellicle) with minimal damage to the tooth enamel and other oral tissue.
U.S. Pat. No. 4,153,680 and GB Patent Application 2,038,303A both disclose the general use of silica hydrogels or hydrated silica gels as dental abrasives.
U.S. Pat. No. 5,939,051 discloses dentifrice compositions prepared with silica gels having low abrasion and high cleaning properties.
U.S. Pat. Nos. 5,658,553 and 5,651,958 disclose dentifrice compositions containing a combination of precipitated silica and silica gels having high cleaning and low abrasion as indicated by their low radioactive dentin abrasion (RDA) values.
Copending patent application U.S. Ser. No. 09/567,402 filed May 9, 2000 discloses a silica hydrogel containing about 10 to about 35% by weight water, whereby the dentifrice composition has an RDA of from 110 to 200, and a PCR of from about 150 to about 300.
In spite of the extensive prior art relating to silica hydrogels and other abrasive compounds used to prepare dentifrice compositions for oral cleaning and stain removal, there is still a need for additional compositions providing improved pellicle cleaning and stain removal.
In accordance with the present invention there is provided a silica abrasive dentifrice composition which exhibits heightened tooth stain removal which composition comprises an orally acceptable vehicle containing a combination of a low oil absorption silica abrasive having an oil absorption value of less than 100 cubic centimeters (cc)/100 grams (g) silica and a proteolytic enzyme.
Low Oil Absorption Silica Abrasives
Silica abrasives useful in the practice of the present invention include silica gels and precipitated amorphous silica having an oil absorption value of less than 100 cc/100 g silica and preferably in the range of from about 45 cc/100 g to less than about 70 cc/100 g silica. These silicas are colloidal particles having an average particle size ranging from about 3 microns to about 12 microns, and more preferably between about 5 to about 10 microns and a pH range from 4 to 10 preferably 6 to 9 when measured as a 5% by weight slurry.
Oil absorption values are measured using the ASTM Rub-Out Method D281. The low oil absorption silica abrasive is present in the oral are compositions of the present invention at a concentration of about 5 to about 40% by weight and preferably about 10 to about 30% by weight.
Low oil absorption silica abrasives particularly useful in the practice of the present invention are marketed under the trade designation Sylodent XWA by Davison Chemical Division of W. R. Grace and Co., Baltimore, Md. 21203. Sylodent 650 XWA, a silica hydrogel composed of particles of colloidal silica having a water content of 29% by weight averaging from about 7 to about 10 microns in diameter, and an oil absorption of less than 70 cc/100 g of silica is a preferred example of a low oil absorption silica abrasive useful in the practice of the present invention.
Another low oil absorption silica abrasive particularly useful in the practice of the present invention is marketed under the trade designation DP-105 by J. M. Huber Chemicals Division, Havre de Grace, Md. 21078 is a precipitated amorphous silica having an average particle size distribution from 5 to 12 microns and an oil absorption in the range of 50 to 70 cc/100 g.
The low oil absorption silica abrasive can be used as the sole abrasive in preparing the dentifrice composition of the present invention or in combination with other known dentifrice abrasives or polishing agents.
Commercially available abrasives which may be used in combination with the low oil absorption silica abrasive include precipitated silicas having a mean particle size of up to about 20 microns, such as Zeodent 115, marketed by J. M. Huber Chemicals Division, Havre de Grace, Md. 21078, or Sylodent 783 marketed by Davison Chemical Division of W. R. Grace and Company. Other useful dentifrice abrasives include sodium metaphosphate, potassium metaphosphate, tricalcium phosphate, dihydrated dicalcium phosphate, aluminum silicate, calcined alumina, bentonite or other siliceous materials, or combinations thereof.
The total quantity of abrasive present in the dentifrice compositions of the present invention is at a level of from about 5% to about 40% by weight, preferably from about 5% to about 30% by weight when the dentifrice composition is a toothpaste.
Enzymes
The proteolytic enzymes useful in the practice of the present invention are those well known protein substances within the class of proteases, which breakdown or hydrolyze proteins (proteases). The proteolytic enzymes are obtained from natural sources or by the action of microorganisms having a nitrogen source and a carbon source. Examples of proteolylic enzymes useful in the practice of the present invention include papain, bromelain, chymotrypsin, ficin and alcalase.
Papain obtained from the milky latex of the Papaya tree is the proteolytic enzyme preferred for use in the practice of the present invention and is incorporated in the oral care composition of the present invention in an amount of about 0.1 to about 10% by weight and preferably about 0.5 to about 5% by weight, such papain having an activity of 150 to 300 units per milligram as determined by the Milk Clot Assay Test of the Biddle Sawyer Group (see J. Biol. Chem., vol. 121, pages 737-745).
Enzymes which may beneficially be used in combination with the proteolytic enzymes include carbohydrases such as glucoamylase, alpha-amylase, beta-amylase, dextranase and mutanase and lipases such as plant lipase, gastric lipase and pancreatic lipase.
Glucoamylase is a saccharifying glucoamylase of Aspergillus niger origin. This enzyme can hydrolyze both the alpha-D-1,6 glucosidic branch points and the alpha-1,4 glucosidic bonds of glucosyl oligosaccharides. The product of this invention comprises about 0.001 to 10% of the carbohydrases. The lipase enzyme used in this invention is derived from a select strain of Aspergillus niger. The enzyme has maximum lipolytic activity at pH 5.0 to 7.0 when assayed with olive oil. The enzyme has 120,000 lipase units per gram.
The carbohydrases and lipases may be included in the dentifrice composition at a concentration of about 0.10 to about 5.0% by weight and preferably about 0.2 to about 2% by weight. Among the carbohydrases useful in accordance with this invention are glucoamylase, alpha and beta-amylase, dextranase and mutanase.
Dentifrice Vehicle
The orally-acceptable dentifrice vehicle used to prepare the dentifrice composition comprises a water-phase, containing a humectant therein. The humectant is preferably glycerin, sorbitol, xylitol, and/or propylene glycol of molecular weight in the range of 200 to 1,000; but, other humectants and mixtures thereof may also be employed. The humectant concentration typically totals about 5 to about 70% by weight of the oral composition.
Reference hereto to sorbitol refers to the material typically commercially available as a 70% aqueous solution. Water is present typically in amount of at least about 10% by weight, and generally about 25 to 70% by weight of the oral composition. Water employed in the preparation of commercially suitable toothpastes should preferably be deionized and free of organic impurities. These amounts of water include the free water which is added plus that which is introduced with other materials such as with sorbitol.
The dentifrice compositions of the present invention can contain a variety of optional dentifrice ingredients. As described below, such optional ingredients can include, but are not limited to, thickening agents, surfactants, a source of fluoride ions, a synthetic anionic polycarboxylate, a flavoring agent, antibacterial agents, antitartar and coloring agents.
Thickening Agents
Thickeners used in the compositions of the present invention include natural and synthetic gums and colloids. Not all naturally occurring polymer thickeners (such as cellulose or carrageenans) are compatible with dentifrice ingredients (specifically enzymes) of dentifrice compositions when formulated in the presence of proteolytic enzymes. Thickeners compatible with proteolytic enzymes include xanthan gum, polyglycols of varying molecular weights sold under the tradename Polyox , and polyvinylpyrrolidone. Compatible inorganic thickeners include amorphous silica compounds which function as thickening agents and include colloidal silicas compounds available under the trade designation Cab-o-sil manufactured by Cabot Corporation and distributed by Lenape Chemical, Bound Brook, N.J.; Zeodent 165 from J. M. Huber Chemicals Division, Havre de Grace, Md. 21078; and Sylodent 15, available from Davison Chemical Division of W. R. Grace Corporation, Baltimore, Md. 21203. Other inorganic thickeners include natural and synthetic clays, lithium magnesium silicate (laponite) and magnesium aluminum silicate (Veegum).
The thickening agent is present in the dentifrice composition in amounts of about 0.1 to about 10% by weight, preferably about 0.5 to about 4.0% by weight.
Surfactants
Surfactants are used in the compositions of the present invention to achieve increased prophylactic action and render the dentifrice compositions more cosmetically acceptable. The surfactant is preferably a detersive material which imparts to the composition detersive and foaming properties.
Anionic surfactants such as higher alkyl sulfates such as sodium lauryl sulfate are not compatible with enzymes. Anionic surfactants facilitate denaturing of the enzyme and loss in activity. As a result, it is important to the practice of the present invention to use a surfactant or combination of surfactants that are compatible with the enzymes present in the toothpaste formulation and provide the requisite foaming characteristics. Examples of enzyme compatible surfactants include nonanionic polyoxyethylene surfactants such as Polyoxamer 407, Steareth 30, Polysorbate 20, and PEG-40 castor oil and amphoteric surfactants such as cocamidopropyl betaine and cocamidopropyl betaine lauryl glucoside. Preferred surfactants include a combination of Polyoxamer 407, polysorbate 20, PEG-40 castor oil and cocamidopropyl betaine at a total surfactant concentration in the dentifrice composition of between about 2 to about 10% by weight and preferably between about 3.5 to about 6.5% by weight at weight ratios of 2.5 Polyaxomer 407, 2.5 PEG-40 castor oil, 3.3 Polysorbate-20 and 1.0 cocamidopropyl betaine.
Fluoride and Other Active Agents
The dentifrice composition of the present invention may also contain a source of fluoride ions or fluorine-providing component, as anticaries agent in amount sufficient to supply about 25 ppm to 5,000 ppm of fluoride ions and include inorganic fluoride salts, such as soluble alkali metal salts. For example, preferred fluoride sources which are compatible with enzymes present in the composition are sodium fluoride, potassium fluoride, sodium fluorosilicate, ammonium fluorosilicate, as well as tin fluorides, such as stannous fluoride and stannous chloride. Sodium fluoride is preferred.
In addition to fluoride compounds, there may also be included antitartar agents such as pyrophosphate salts including dialkali or tetraalkali metal pyrophosphate salts such as Na4P2O7, K4P2O7, Na2K2P2O7, Na2H2P2O7 and K2H2P2O7 long chain polyphosphates such as sodium hexametaphosphate and cyclic phosphates such as sodium trimetaphosphate. These antitartar agents are included in the dentifrice composition at a concentration of about 1 to about 5% by weight.
Another active agent useful in dentifrice compositions of the present invention are antibacterial agents, which can be from 0.2 to 1.0% by weight of the dentifrice composition. Such useful antibacterial agents include non-cationic antibacterial agents which are based on phenolic or bisphenolic compounds, such as halogenated diphenyl ethers such as Triclosan (2,4,4xe2x80x2-trichloro-2xe2x80x2-hydroxydiphenyl ether).
Enzyme Stabilizing Agents
The dentifrice composition of the present invention may also contain ingredients which stabilize enzymes in a dentifrice environment. These stabilizers protect the enzyme from inactivation by chelating metal impurities present in the dentifrice composition which have the propensity to denature the active site of the enzyme by protecting the enzyme from oxidation. Chelating agents include, ethylene diamine tetraacetic acid (EDTA) and sodium gluconate at concentrations between 0.01 and 1%, preferably between 0.1 and 0.5%. Agents stabilizing the enzyme against oxidation include sodium bisulfite, metal gallates, sodium stannate and ascorbic acid at concentrations between about 0.1 and about 1.5%, preferably between about 0.3 and about 0.75%.
Anionic Polycarboxylate
Synthetic anionic polycarboxylates may also be used in the dentifrice compositions of the present invention as an efficacy enhancing agent for any antibacterial, antitartar or other active agent within the dentifrice composition. Such anionic polycarboxylates are generally employed in the form of their free acids or preferably partially or more preferably fully neutralized water soluble alkali metal (e.g. potassium and preferably sodium) or ammonium salts. Preferred are 1:4 to 4:1 copolymers of maleic anhydride or acid with another polymerizable ethylenically unsaturated monomer, preferably methylvinylether/maleic anhydride having a molecular weight (M.W.) of about 30,000 to about 1,800,000 most preferably about 30,000 to about 700,000. Examples of these copolymers are available from GAF Corporation under the tradename Gantrez, e.g. AN 139 (M.W. 500,000), AN 119 (M.W. 250,000); S-97 Pharmaceutical Grade (M.W. 700,000), AN 169 (M.W. 1,200,000-1,800,000), and AN 179 (M.W. above 1,800,000); wherein the preferred copolymer is S-97 Pharmaceutical Grade (M.W. 700,000).
When present, the anionic polycarboxylates is employed in amounts effective to achieve the desired enhancement of the efficacy of any antibacterial, antitartar or other active agent within the dentifrice composition. Generally, the anionic polycarboxylates is present within the dentifrice composition from about 0.05% to about 4% by weight, preferably from about 0.5% to about 2.5% by weight.
Flavor
The dentifrice composition of the present invention may also contain a flavoring agent. Flavoring agents which are used in the practice of the present invention include essential oils as well as various flavoring aldehydes, esters, alcohols, and similar materials. Examples of the essential oils include oils of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon, lime, grapefruit, and orange. Also useful are such chemicals as menthol, carvone, and anethole. Of these, the most commonly employed are the oils of peppermint and spearmint.
The flavoring agent is incorporated in the dentifrice composition at a concentration of about 0.1 to about 5% by weight and preferably about 0.5 to about 1.5% by weight.
Other Ingredients
Various other materials may be incorporated in the dentifrice compositions of this invention, including desensitizers, such as potassium nitrate; whitening agents, such as hydrogen peroxide, calcium peroxide and urea peroxide; preservatives; silicones; and chlorophyll compounds. These additives, when present, are incorporated in the dentifrice composition in amounts which do not substantially adversely affect the properties and characteristics desired.
Preparation of the Dentifrice
The preparation of dentifrices is well known in the art by reference. More specifically, to prepare a dentifrice of the present invention, generally the humectants e.g. glycerin, sorbitol, propylene glycol, and polyethylene glycol; are dispersed in the water in a conventional mixer under agitation. Into the dispersion are added the enzyme or enzymes organic thickeners, such as xanthan gum; any anionic polycarboxylate; any salts, such as sodium fluoride anticaries agents; tetrasodium pyrophosphate, sodium tripolyphasphate anticalculus salts and any sweeteners; the resultant mixture is agitated until a homogeneous gel phase is formed. Into the gel phase are added a pigment such as TiO2, and any acid or base required to adjust the pH. These ingredients are mixed until a homogenous phase is obtained. The mixture is then transferred to a high speed/vacuum mixer; wherein, the inorganic silica thickener, such as Zeodent 165; and surfactant ingredients are added to the mixture. The low oil absorption silica abrasive is added at this point, along with other abrasives to be used in the composition. Any water insoluble antibacterial agent, such as Triclosan, is solubilized in the flavor oils to be included in the dentifrice and the solution is added along with the surfactants to the mixture, which is then mixed at high speed for from 5 to 30 minutes, under vacuum of from about 20 to 50 mm of Hg, preferably about 30 mm Hg. The resultant product is in each case a homogeneous, semi-solid, extrudable paste or gel product.

Oral composition providing enhanced tooth stain removal