Alcohol based aerosol spray compositions which contain 1-20% of an alcohol-soluble polymer which, on evaporation, leaves on a sprayed surface a film which acts as a barrier to dust, dust mites and their faecal excretions. These compositions optionally can include an acaricidal ingredient, such as benzyl benzoate, and one or more antimicrobial ingredients such as a quaternary ammonium salt.

This invention relates to alcohol-based disinfectant compositions containing one or more additional ingredients which form a barrier against dust particles and particularly dust mites and their allergens. More specifically, the invention relates to aerosol spray disinfectants suitable for indoor use which, in addition to having the usual antimicrobial properties, are also effective in preventing people from coming in contact with allergens found in dust, notably dust mite allergens. The invention also provides methods for effectively controlling dust mites and their allergens and for significantly reducing their attendant adverse reactions.
Common house dust is an important cause of asthma, rhinitis, atopic dermatitis, eczema and other allergic conditions in sensitive individuals. Household dust generally comprises a variety of particulate matter including pollen, dust mites, dust mite allergens, dirt, skin cells, animal dander, insect parts, pillow feathers, food particles and mould spores. The particular constituents of dust will depend on location within the house, whether pets are present and other obvious factors. One of the principal sources of allergies is dust mites, which inhabit rugs, carpets, and other fabric surfaces, particularly sofas, mattresses, pillows, upholstered chairs and the like. The mite Dermatophygoides pteronyssinus has been identified as a major source of house dust allergen. This mite and the related mites D. farinae, D. microceras and Euroglyphus maynei are the predominant house dust mites in temperate climates in North America, Europe, Australia and other areas.
Dust mites are not insects, but are eight-legged arachnids, relatives to ticks and spiders. They live in close association with humans (or other mammals), their main food source being the shed scales from skin. Adult mites are approximately 300 microns ({fraction (3/10)} mm) in size, having developed over approximately 25 days through egg, larval and nymph stages. Adults live for 2 to 3xc2xd months, during which time each female can produce about 20-40 eggs. Dust mites are photophobic, living deep in pillows, mattresses, carpets, upholstered furniture and other soft materials.
In addition to a food source, the other essential requirement for dust mite growth is adequate humidity. Dust mites are 75% water by weight. They do not drink water, but must absorb water vapor from the air in order to survive. Specialized glands above their pairs of legs produce secretions high in sodium and potassium chloride, which act to absorb water vapor from surrounding air. This can only be accomplished if the surrounding humidity is sufficiently high. Relative humidities of about 65-80% at temperatures ranging from about 20 to 35 C are optimal for dust mite growth. Dust mites will die at humidities of 50% or less. In geographical areas where humidity is high, dust mites are present in nearly all homes and may be as plentiful as 18,000 mites per gram of dust. Literally millions of mites can inhibit a single bed or rug.
A major dust mite allergen is present in mite faecal particles. Each mite produces about 20 faecal particles per day, and more than 100,000 of them may be present in a gram of dust. These particles vary from about 10 to 40 microns in size, comparable to the size of pollen grains, and become airborne during domestic activity such as making beds and vacuuming carpets.
Group I allergens (dermatophagoides farinae I-Der f I and dermatophagoides pteronyssinus I-Der p I) are heat labile, 24,000 molecular weight glycoproteins (hydrolytic enzymes). These allergens appear to be structural homologues and have very similar N-terminal amino acid sequences. These group I allergens are regarded as the most important and are excreted in their highest concentrations by the mite""s gastrointestinal tract in the form of mite""s faecal particles, suggesting that they are associated with digestion. They elute rapidly (within 2 minutes) from isolated faecal particles, but very slow from mite bodies.
Group II allergens (Der p II and Der f II) are 15,000 molecular weight proteins with almost identical N-terminal amino acid sequences that are also secreted by the mite""s gastrointestinal tract in the form of faecal allergens, although not in as high a concentration as the group I allergens. This suggests that they probably derived from a source other than the gut. Their actual function has not been determined.
Most mite-allergic individuals produce antibodies to both the group I and group II allergens.
Acute exposure to mite allergens has been shown to induce wheezing, rhinitis, eustachian tube obstruction or eczema in sensitized patients. Chronic exposure can cause bronchial hyper-reactivity and chronic asthma. There is a correlation between the level of exposure to house dust mite allergen in early childhood and the likelihood of the subsequent development of asthma. Conversely, asthmatics sensitive to dust mites improve in environments without mites, such as at high altitudes or in hospital rooms. Attempts have therefore been made to decrease patients"" exposure to dust mites in the home.
Studies of dust avoidance measures in homes have shown that the use of impermeable mattress and pillow encasings and the removal of bedroom carpeting are associated with a decrease in mite counts. These measures have also been shown to be of clinical value, with a decrease in symptoms and medication requirements occurring in children and adults with dust-sensitive asthma when pillows and mattresses are encased and carpets are removed.
Although carpets and upholstered furniture are major sites of dust mite growth, many allergic individuals are unable or unwilling to remove these from their home. Ordinary vacuuming does not remove dust mites or significantly decrease dust mite allergen levels, and in fact, vacuuming of carpets with the usual household appliances actually increases the amount of airborne dust. However, the use of special filters such as HEPA (High Efficiency Particulate Air) filters or two-ply vacuum bags, and/or the employment of central vacuuming systems (where the dust is collected in a receptacle remote from the room being cleaned) have been helpful. Nevertheless, vacuuming seldom removes all of the live mites, mainly because the mites have little suction cups on the tops of their legs which cause them to cling to textile fibres.
Various chemical agents have been used against mites, including: compounds known under the common names as resuethrin, phenothrin, permethrin, allethrins, tetramethrin, furamethrin, cypermethiin, decamethrin, phenvalerate, phenpropathrin, terallethrin, empenthrin and pyrethrin; pyrethroid compounds such as 1-ethynyl-2-methyl-2-pentenyl-2,2-dimethyl-3,3-(2,2-dichlorovinyl)-cyclopropane-1-carboxylate, 1-ethynyl-2-methyl-2-pentenyl-2,2,3,3-tetramethylcyclopropane-1-carboxylate, xcex1-cyano-3-phenoxybenzyl-2,2-dimethyl-3-(2,2,3-tribromomethyl)-cyclopropane-1-carboxylate; organic phosphorus compounds such as sumithion, fenthion, tetrachlorvinphos, diazinon and DDVP; and carbamate compounds such as those sold under the trademarks Baygon and Sevin. However, these conventional miticides are expensive and are often either toxic to human beings or have the potential themselves to cause allergic or other adverse reactions. Therefore, the use of such compounds in a household environment cannot be the solution to controlling the population of dust mites.
A number of less toxic miticidal agents have been proposed for use in controlling dust mites. As noted in U.S. Pat. No. 4,800,196, these include phenyl salicylate, diphenylamine, methyl beta-naphthyl ketone, coumarin, phenethyl benzoate, benzyl salicylate, phenyl benzoate, N-fluorodichloromethylthio-cyclohexene-dicarboxyimide, p-nitrobenzoic acid methyl ester, p-chlorometaxylenol, xcex1-bromocinnamic aldehyde, 2,5-dichloro-4-bromophenol, 2-phenylphenol, sodium 2-phenylphenolate, 5-chloro-2-methyl-4-isothiazoline-3-one, 2-methyl-4-isothiazoline-3-one and benzimidazolylmethylcarbamate. These can be used in the form of solutions, wettable powders, granules, sprays, etc.
While many of these compounds have some degree of effectiveness against dust mites, their use is not without attendant shortcomings. For example, many of them are rather expensive to produce and/or may be difficult to form into compositions for ordinary domestic use. Elimination of dust in a household environment is a task which is intensely disliked to the point where the average householder is no longer embarrassed by a moderate layer of dust or the presence of xe2x80x9cdust bunniesxe2x80x9d under beds or behind furniture. Furthermore, as noted above, dust removal and/or vacuuming often stirs up the dust mites and their attendant allergens and, temporarily at least, causes more distress to allergic persons.
More effective methods of reducing exposure to dust mites and their faecal matter, have been developed which do not depend on the diligence of the householder in removing dust.
U.S. Pat. No. 5,271,947 features the use of finely divided sodium chloride powder as a method for killing mites and controlling their allergen-bearing faeces. The powder has the consistency of talcum powder and is used, for example, by applying the powder with a broom or brush to carpets and other textile materials. However, one of the disadvantages in using sodium chloride powder is its hygroscopicity; if the amount used is not carefully controlled, the salt will absorb moisture from the air, particularly in humid climates.
One of the more effective agents for killing dust mites is benzyl benzoate, a compound which is readily available and inexpensive. Powder formulations containing benzyl benzoate are commercially available for application to carpets. British Patent No. 1,368,657 teaches the use of a composition for treating bedding and similar materials which comprises benzyl benzoate and polyethylene glycol, or an ether or ester thereof, as an evaporation retarding agent. British Patent No. 2,042,893 teaches the use of a composition comprising benzyl benzoate and a fatty acid ester for application to bedding and also for treating the skin. A similar composition for general miticidal use in households is taught in published Japanese Patent Application No. 61-91103.
More generally, Bischoff U.S. Pat. No. 4,666,940 teaches the use of various miticidal agents, including particularly benzyl benzoate, as a component in cleansing compositions. The disclosed compositions can also contain dissolved or dispersed plastic materials, but said materials must form discrete particles of particular size and must not form a film.
European Patent Application No. 0,612,469 discloses laundry detergents comprising benzyl benzoate, which compositions are taught to be effective in killing the dust mites present on the articles to be laundered.
In an article by G. Schober et al., xe2x80x9cControl of House-Dust Mites (Pyroglyphidae) with Home Disinfectantsxe2x80x9d, Experimental and Applied Acarology 3:179-89 (1987), the authors provide data showing that the addition of benzyl benzoate to certain commercially available carpet cleaning formulations results in a composition with better acaricidal properties than other known acaricides.
U.S. Pat. No. 5,180,586 discloses that certain compounds, previously known for use as perfuming agents in foods and cosmetics, have been found to be effective in killing dust mites.
To summarize the published literature, it is apparent that benzyl benzoate and other miticidal compounds disclosed in the art can, under proper conditions of use, be effective in killing dust mites and thus helpful in reducing the level of allergens produced by said mites. Laundering and dry cleaning of textiles and fabrics can also be effective under certain conditions, but this is not practical for day-to-day control.
The principal problem associated with previous methods for controlling dust mites and their allergens is the fact that frequently the mites and their faecal particles are not completely removed. At best, compositions containing acaricidally effective compounds will kill off the mites, but will not remove their faecal matter and the associated allergens. Vacuuming, either by itself or as a final step in a method involving chemical treatment, is often not effective because the pick-up nozzle of the vacuum cleaner cannot effectively fit into all of the crevices in upholstered furniture. Furthermore, unless vacuuming is done under special conditions such as use of a two-ply vacuum bag or HEPA filter, the allergens will be dispersed into the ambient air, therefore doing more harm than good. Therefore, it would be desirable to have a method for controlling dust mites and their associated allergens which would avoid the various disadvantages of the methods heretofore used.
Accordingly, it is a principal object of this invention to provide improved methods for controlling dust particles, in particular, dust mites and the allergens present in their faecal excretions.
It is a further object of this invention to prevent the allergens present in dust and, in particular, dust mites, from entering into the ambient air of indoor spaces.
Another object of this invention is to provide compositions which can be used in attaining the aforementioned objects.
This invention provides alcohol-based aerosol spray compositions which additionally contain from about 1.0% to about 20.0% of a polymer which is soluble in said alcohol and which, on evaporation, leaves on a sprayed surface a film which acts as a barrier to dust, dust mites and their faecal excretions. (All percentages throughout this disclosure are to be understood as percentages by weight.) The compositions typically also contain water in an amount ranging from 0 to 59%. Alternatively, the polymer can be one which is water-soluble, or one which is soluble in both water and the alcohol; it is preferred that the polymer be soluble in at least the alcohol. In addition, the compositions optionally can include from about 0.1% to, about 10% of an acaricidal ingredient such as benzyl benzoate. Said compositions, in addition to their usual disinfecting properties, are effective aids for controlling dust mites and, when the compositions also contain an acaricidal ingredient, also kill the mites. The compositions can also comprise one or more additional disinfectants such as a quaternary ammonium compound, a phenol-based antimicrobial agent, or a botanical oil with disinfectant properties. The compositions can also comprise a suitable propellant, and other ingredients such as wetting agents, surfactants, preservatives and anti-corrosion agents.
The mites and allergens associated with dust mites can be controlled by applying, more particularly by spraying, the compositions of this invention onto the surface of textile fabrics infested with said mites. This sets up a barrier which prevents the dust mites and their excreted faecal matter from coming in contact with people. In addition, in the embodiment of this invention where the composition additionally includes an acaricidal ingredient such as benzyl benzoate, the mites are killed and the production of additional allergens thereby halted.
The method according to this invention comprises, in its broadest sense, spraying onto a textile fabric surface an alcohol-based disinfecting composition which contains from about 1.0% to about 20.0% of a polymer soluble in said alcohol and which, on evaporation, leaves on the surface a film which acts as a barrier to dust mites and their faecal excretions and to other particles present in household dust and their associated allergens. The compositions typically also comprise water and, alternatively, the polymer can be one which is water-soluble. The compositions optionally can include from about 0.1% to about 10% of an acaricidal ingredient such as benzyl benzoate, in which case the method is additionally a method for killing dust mites. In many circumstances, particularly with the infestation of dust mites is not great, this spraying step will provide effective control of dust mite allergens by preventing their escape into the ambient air.
A more effective method for control of dust particles, in particular dust mites and their associated faecal matter, is to remove as many dust mites and faecal particles as possible by vacuuming under conditions where the particles are not blown into the ambient air; for example, using a two-ply filter system or an HEPA system. The vacuuming step is then followed up by spraying the fabric surface with a composition described above.
A still further procedure for dust mite control involves a three-step method, the first step being application to the fabric surface, for example, by spraying of a composition comprising a known acaricidal agent, such as benzyl benzoate. This is followed up, after a suitable time for drying, by vacuuming as discussed above. In this procedure, the vacuuming step is somewhat more effective since most of the mites are dead and not clinging to the fibres. The final step is spraying the fabric surface with an aerosol composition according to this invention.
The aerosol compositions of this invention comprise, as essential ingredients, an alcohol having from 1 to 4 carbon atoms, preferably ethanol, and a polymer soluble in the alcohol, which results in a barrier film on a surface when the alcohol evaporates. The compositions will typically and preferably also comprise up to about 15% of water and, as an alternative, the polymer can be one which is soluble in water. However, the use of an alcohol-soluble polymer is preferable in view of the faster evaporation rate of alcohol.
The compositions can also include an acaricidal ingredient such as benzyl benzoate or another known chemical substance effective against dust mites such as those disclosed in U.S. Pat. No. 4,800,196, pertinent portions of which are incorporated herein by reference.
In view of the fact that dust mites are invisible to the naked eye, it is logical, from a commercial point of view, to control dust mites simultaneously with killing or controlling other invisible organisms such as bacteria. Aerosol disinfectant compositions have attained wide consumer acceptance and the addition of one or more ingredients which will control dust mites and/or remove the dust mite allergens from ambient air has an extremely beneficial purpose and there is no need to persuade potential consumers to purchase an additional household care product specifically for the purpose of dust mite control.
As contemplated by this invention, the principal disinfecting ingredient is a low molecular weight alcohol, typically an alcohol having from 1-4 carbon atoms such as methanol, ethanol or isopropanol, with ethanol being preferred. The disinfecting properties of such alcohols are well known. They form the basis of many commercial disinfecting compositions and such compositions have attained great consumer acceptance. In addition to its disinfecting properties, the alcohol also functions as a solvent for the polymer and for some of the other ingredients optionally present in the compositions of this invention and provides for rapid drying time in a household environment.
The amount of alcohol present in the composition ranges from about 30% to 90%, preferably from 70% to 85%, based on the weight of the composition, and exclusive of any propellant contained in said composition.
Water, if present in the composition, can comprise up to about 59% of said composition. Preferably, any water present will be in the 5 to 15% range.
The polymer used in the compositions of this invention is preferably one which is soluble in the alcohol component and must be a polymer which, after spraying and evaporation of the solvents in the composition, will leave a protective barrier film on the sprayed surface. Obviously, any such polymer must meet the criteria of consumer safety and, since the contemplated use of the compositions is in an indoor environment, the polymer should not have an offensive odor. All polymers which meet the foregoing criteria are suitable for inclusion in the subject compositions and these include, but are not limited to, polyester resins, acrylate polymers and copolymers, methacrylate polymers and copolymers, polyvinyl pyrrolidone and copolymers comprising vinyl pyrrolidone, butyl maleate/isobornyl acrylate copolymers, thermoplastic polyamides, nylon resins, polyvinyl alcohols and polyether polyols. A suitable group of ethanol-soluble polymers are polyacrylates and their copolymers. Because of their known safety, film-forming polymers used in hair treatment formulations have been found to be especially suitable. Examples include certain of the products sold under the following trade designations: Advantage CP, Gaffix, Gantrez and the PVP/VA Series of International Specialty Products; Amphomer, Versatyl and Resyn of National Starch and Chemical Company; Dantoin of Lonza Inc.; Delsette of Hercules Incorporated; Diaformer of Clariant Corporation; Luviflex, Luviset, Luviquat and Luviscol of BASF Corporation; and Stepanhold of Stepan Company. These polymeric substances are generally soluble in ethanol; some are also soluble in water. The significant feature of the polymer useable in this invention is that it must form a film which will act as a barrier to both dust mites themselves and to their faecal excretions. A powder is not suitable for this purpose, and likewise a polymer film which immediately breaks down to flakes or particles will not be suitable. The film should remain intact for at least seven days, preferably for a period of from 10 to 30 days.
The amount of polymeric material in the composition is from about 1% to about 20% by weight, preferably from 1% to 7%, and more preferably from 2% to 5% by weight, exclusive of any propellent in said composition.
In another embodiment of this invention, the subject compositions additionally contain a miticidal ingredient, such as benzyl benzoate, in an amount of up to about 10% by weight. Preferably, the benzyl benzoate is present in an amount ranging from 0.5% to 8%, and more preferably from 1% to 7%.
The compositions of this invention may also contain one or more additional antimicrobial agents in order to increase the antimicrobial effectiveness of the composition up to a level defined by the United States Environmental Protection Agency as xe2x80x9chospital strength disinfectionxe2x80x9d. The term xe2x80x9chospital strengthxe2x80x9d is not intended to indicate that the subject compositions are restricted to use in hospitals and other health care facilities; rather such disinfectant compositions are commonly sold for domestic use, and the term simply indicates a higher level of disinfective activity.
Although any known disinfecting agent can be used as an optional additional component, preferably the disinfectant agent will comprise one or more quaternary ammonium compounds commonly used as disinfectants or one or more of the well known phenolic compounds such as ortho-phenylphenol. The additional antimicrobial ingredient may be present in the composition in amounts ranging from about 0.01 weight percent to about 1 weight percent, preferably from 0.05 to 0.5 weight percent, and more preferably about 0.1%, based on total weight of the composition.
If the additional antimicrobial component is a quaternary ammonium salt, any of the broad classes of suitable quaternary ammonium compounds may be used. More than one quaternary ammonium compound is employed to assist in providing a broader spectrum antimicrobial efficacy. Useful quaternary ammonium compounds include, for example, those quaternary ammonium compounds represented by the formula:
wherein R1, R2, R3, and R4 may be described in three general groups. The counterion X may be any salt-forming anion which permits water solubility of the quaternary ammonium complex. Exemplary counterions include halides, for example chloride, bromide or iodide, or methosulfate.
In a first group of preferred quaternary ammonium compounds, R1 and R2 are C1-C7 alkyl groups (preferably methyl groups); R3 is a benzyl group or a benzyl group substituted with an alkyl group having about 1 to 18 carbon atoms or an alkyl group having about 8 to 20, and preferably 8 to 18, carbon atoms; R4 is a benzyl group or a benzyl group substituted with an alkyl group having about 1 to 18 carbon atoms, and R4 is a benzyl group or a benzyl group substituted with an alkyl group having about 1 to 18 carbon atoms or an alkyl group having about 8 to 20, and preferably 8 to 18 carbon atoms.
In a second group of preferred quaternary compounds, R1, R2 and R3 are C1 to C7 alkyl (preferably methyl groups); and R4 is an alkyl, an alkyl-substituted benzyl, or a phenyl-substituted alkyl group having a total of from about 8 to 20, and preferably 8 to 18, carbon atoms.
In a third group of preferred quaternary ammonium compounds, R1 is an alkyl, an alkyl substituted benzyl, or a phenyl substituted alkyl group having a total of from about 10 to 20, and preferably from 12 to 16 carbon atoms; R2 is a C1-C7 alkyl (preferably a methyl group); R3 is [CH2CH2O]xH; and R4 [CH2CH2O]yH, with the sum of x+y varying between about 2 and 50 (preferably 2 and 5). For all these groups, X may be a halide (preferably chloride or bromide) or may be a suitable organic anion such as benzoate or saccharinate.
Quaternary ammonium compounds are well known and available commercially from a number of suppliers. For example, diallcyl dimethyl ammonium chloride is available in approximately 50% active ingredient solution as Bardac-2050 quaternary ammonium compound from Lonza, Inc. (Fairlawn, N.J.) and Bio-Dac-50-20 quaternary ammonium compounds is available from Bio-Labs (Decatur, Ga.), both of which are mixtures of approximately 25% octadecyl dimethyl ammonium chloride, about 10% dioctyl dimethyl ammonium chloride, about 15% didecyl dimethyl ammonium chloride in a solvent solution containing about 10-20% ethyl alcohol and 30-40% water. Also, for example, alkyl dimethyl benzyl ammonium chloride is available in an approximately 80% active ingredient solution as BTC-8358 from Stepan Co. (Northfield, Ill.); Bio-Quat-80-28RX from Bio Lab, and Barquat-MB80-10 is available from Lonza. The latter two have an alkyl distribution of approximately C14 (50%), C12 (40%) and C16 (10%), and diluents of ethyl alcohol (10%) and water (10%). In addition, a dialkyl dimethylbenzyl ammonium saccharinate in 33% alcohol solution is available from Stepan Company as Onyxide 3300.
If the additional antimicrobial ingredient is a phenolic derivative, any suitable phenol compound may be used. These include phenol, halogenated phenols, phenylphenols particularly ortho-phenylphenol, xylenols, nitrophenols, cursols, thymol, nitrophenols, aminophenols, and many others well known in the art.
The compositions of this invention may also include one or more surfactants in concentration ranging from 0.035 to about 10 weight percent, preferably from 0.04 to 2 weight percent based on the total weight of the composition (excluding the propellant required in aerosol formulations). The surfactants can be cationic, anionic, or nonionic. However, when the compositions contain a quaternary ammonium compound as an additional disinfecting agent, the surfactants present should be limited to nonionic surfactants.
Examples of suitable nonionic surfactants are as follows: ethoxylated fatty alcohols containing from 11 to 15 carbon atoms in the alcohol and from 3 to 40 moles of ethylene oxide (Tergitol nonionics, Union Carbide Corporation), isomeric linear secondary alcohols with 11 to 15 carbon atoms and 9 moles of ethylene oxide (Tergitol 15-S-9), and linear primary alcohols with 12 to 15 carbon atoms and 9 moles of ethylene oxide (Tergitol 25-L-9); the block copolymers of polyoxyethylenepolyoxypropylene (xe2x80x9cTetronic series nonionic surfactantsxe2x80x9d, BASF Wyandotte Corporation); ethylene glycol-reacted polyoxyethylene-polyoxypropylene copolymers of the formula [HO(CH2Cxe2x80x94H2O)x(CHCH3xe2x80x94CH2O)y(CH2CH2O)z)2H], such as, for example, where x, y and z respectively are 13, 30 and 13 (Pluronic L-64; BASF Wyandotte Corporation); alkyl phenol ethoxylates such as nonylphenoxypolyethoxyephenol ethoxylates or nonylphenoxypolyethoxyethanol with 9 to 10 moles of ethylene oxide (Triton N-101; Rohm and Haas Co.); alkanolamides for example, fatty acid alkanolamides having one or two hydroxyethyl or hydroxypropyl groups such as coconut and tallow fatty acid ethanolamide and diethanolamide, and oleic acid diethanolamide; and silicone glycol copolymers such as those sold as Dow Corning 190, 193 or 1315.
The compositions of this invention should have a pH in the range of 8 to 11. In order to attain a suitable pH, it is usually necessary to add alkalising agents which include well-known substances such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, mono-, di- and tri-ethanol amines, and other agents well known in the art.
The compositions of the invention may also comprise one or more optional constituents including, but not limited to: pH buffering agents, preservatives, fragrances, fragrance carriers and adjuvants which increase their miscibility in the aqueous compositions, colorants, hydrotropes, antifoaming agents, anti-oxidants and corrosion inhibitors, as well as others known to the art but not particularly elucidated herein.
In a preferred form, the compositions of this invention are supplied in self-contained valve controlled aerosol units which provide a fine spray or foam upon activation of the valve. The aerosol container unit consists of a pressure-tight aerosol container having a valve control opening and containing the composition of this invention and from about 2 to about 10% of a propellant. Propellants are selected from the well known compatible propellants such as carbon dioxide, isobutane, n-butane, n-propane and mixtures thereof The propellant used should not adversely react with any components of the composition.
In the methods according to this invention, the subject compositions are sprayed onto textile surfaces such as sofas, upholstered chairs, bedding, pillows, rugs, carpets, etc. known to be infested with dust mites. Although in describing all of these methods, emphasis is placed on dust mites and their allergens, it should be understood that these methods are equally effective against dust particles in general and against other allergens associated therewith, including pollen and animal dander. The preferred mode of application is by means of a self-contained aerosol spraying device. Spraying should be carefully done, ensuring that, for example, all sides of pillows are sprayed, that the spray reaches to comers and crevices, etc. The spraying step alone will reduce the amount of allergens by preventing the escape of dust mite faecal particles into the ambient atmosphere.
A more effective method of dust mite control involves an initial step of vacuuming up from textile surfaces as many as possible of the dust mites and their associated faecal particles. It is important, when performing this step, that the vacuuming be done under conditions whereby the particles are not blown into the ambient air. A central vacuum system, where a holding bag is remote from the area being cleaned, will fulfill this purpose. However, since this is not practical in most households, an acceptable alternative is to use a vacuum system which has a high performance filter, such HEPA filters, or to employ a two-ply vacuum bag. Immediately after the vacuuming step, the compositions of this invention should be sprayed onto the textile surfaces according to the method described above. It is particularly advantageous to apply the compositions immediately after vacuuming since the vacuuming step will have removed most of the dust particles, thereby permitting the film formed by the composition to make closer contact with the fabric surface. Additionally, if the composition contains an acaricidal ingredient, such as benzyl benzoate, the composition will also kill off the mites which have not been removed in the vacuuming step.
An even more effective method of dust mite control includes, as a preliminary first step, the application of a composition comprising an acaricidally effective ingredient such as, for example, benzyl benzoate. These compositions, which are most conveniently applied in aerosol form, should be sprayed onto the fabric surface, permitted to dry, and then vacuumed up with a vacuuming system of the type described in the foregoing paragraph.
In this method, which is recommended for severe mite infestations, the dust mites are killed, and the dead mites and their faecal particles are removed. This should be followed up immediately by spraying onto the surface a composition according to this invention. If the composition includes an acaricidal ingredient, such as benzyl benzoate, in addition to the film forming polymer, any mites which survived the onslaught of the first two steps of the process, are likely to be killed.

Methods for controlling dust mites and the allergens produced by dust mites


Superabsorbent polymers having a slow rate of absorption, and a process for their preparation. The superabsorbent polymer has a slow rate of absorption, is crosslinked with a covalent crosslinking agent and the metal of a polyvalent metal salt and has an Absorption Rate Index of at least about 5 minutes. Such polymers are prepared by contacting a substrate water-swellable, water-insoluble polymer particle with a polyvalent metal salt solution under conditions such that there is formed a polymer having an Absorption Rate Index of at least about 5 minutes.

This invention relates to superabsorbent polymer (SAP) compositions and a process for preparing said compositions.
Superabsorbent polymers are well-known materials which commonly are used in personal care articles such as diapers. These polymers are known to absorb several times their weight of, for example, water, saline solution, urine, blood, and serous bodily fluids.
The development of increasingly thinner diapers has led to diapers having a high density absorbent core, the core having an increased superabsorbent polymer fraction in the superabsorbent polymer/cellulose fluff mixture. Accordingly, the need to have homogeneous distribution of liquid in the absorbent core is increasingly important in order to fully utilize the highly swellable polymer""s storage capacity. However, the distribution of liquid is negatively affected by a reduction in the amount of cellulose fluff in the absorbent core. Thus, additional requirements are now being placed on the highly swellable, liquid-storing polymers in terms of liquid management. The liquid-storing polymers must allow, or support, the distribution of the liquid within the superabsorbent polymer/fluff mix, even in a superabsorbent polymer/fluff mix with a high fraction of highly swellable polymers.
In diapers having a high superabsorbent polymer/fluff ratio, the low fluff content can result in poorer liquid distribution, since the distribution capacity of the fluff is insufficient to compensate for the high absorption rate and absorption capacity of conventional superabsorbent polymers. Accordingly, a very large proportion of body fluid entering a personal care article is absorbed by the superabsorbent polymer in the immediate vicinity of the point of fluid entry.
The swelling of a conventional superabsorbent polymer occurs in such a way that a very high absorption rate is observed immediately after an aqueous liquid is added. After only a few minutes, a highly swellable polymer based on crosslinked, partially neutralized polyacrylate has achieved approximately 95% of its absorption capacity, under conditions of free swelling. This behavior is a typical property of crosslinked polyacrylate superabsorbent polymers.
The rapid expansion of the polymer particles around the point of entry of the body fluid into the area of the absorbent core causes a closing of the interstitial spaces and pores in the SAP-fluff matrix. Since the transport of liquid by diffusion through a swollen hydrogel is much slower than transport through the interstitial spaces, a sealing effect occurs in the area of fluid entry. This effect is often referred to as xe2x80x9cgel blocking.xe2x80x9d Subsequent amounts of fluid can no longer penetrate into the absorbent core and tend to flow in an uncontrolled manner across the surface of the already superficially saturated area to its edge, resulting in undesirable leakage from the absorbent core.
In addition, the storage capacity of the absorbent core decreases, since as a result of the gel blocking of the particles near the surface, the highly swellable polymers embedded deeper in the absorbent core can no longer be reached by subsequent body fluid doses, and hence can not contribute to the total storage capacity.
One approach to the gel blocking problem is to alter the absorption velocity properties of the superabsorbent polymers. For example, U.S. Pat. No. 4,548,847 describes hydrogels reversibly crosslinked by means of at least divalent metal cations, such as Ca+2 or Ba+2. The patent teaches that a delay in swelling can be accomplished by application of a so-called xe2x80x9ccation removal agent.xe2x80x9d Preferred examples of these are water-soluble compounds such as Na2HPO4, sodium hexameta-phosphate and the disodium salt of ethylenediaminetetraacetic acid. The effect of these substances is that the reversible crosslinking sites formed by at least divalent metal cations are destroyed by the cation removal agent. With reduced crosslinking density, the product is able to swell more. The patent also describes absorbent articles that contain the absorbent polymers with the delayed swelling feature. An absorbent article built in layers (wound dressing) is described, for instance, in which each layer contains the polymers according to the invention.
GB 2,280,115 A describes an absorbent article that contains coated superabsorbent particles in the area in which body fluids are released. The coating of the superabsorbent particles prevents swelling until the coating has dissolved in the test or body fluid or has been penetrated by it. These are superabsorbent particles that exhibit an activation time until swelling begins, which time can be varied by the coating""s material and thickness. Some of the coating materials disclosed are non-reactive polysaccharides such as gelatin, microcrystalline cellulose and cellulose derivatives. The activation period to the start of swelling should be at least 5, preferably 15 and more strongly preferred, 60 minutes.
Coated superabsorbent polymers have the disadvantage that even a small initial wetting, without necessarily leading to the swelling of the highly swellable polymers, leads to a destruction of the surface treatment by dissolution, detachment, swelling or decomposition. Once the coating around the polymers has dissolved, such superabsorbent polymers exhibit the high swelling rate of a conventional material without surface treatment. Thus the desired effect of improved liquid management in the absorbent material is lost.
EP 0 631 768 A1 describes an absorbent article that uses superabsorbent polymers with different absorption velocities. The differences in absorption velocities between the various conventional superabsorbent polymers used arise from different particle size distributions (type 1: 600-850 xcexcm, type 2:  less than 250 xcexcm) and are correspondingly small.
U.S. Pat. No. 5,115,011 addresses the gel blocking problem by contacting a water absorbent polymer with an aqueous solution of two water soluble salts, the first being a halogen, sulfate, acetate or nitrate of aluminum, calcium or magnesium, and the second being a monovalent metal salt or ammonium salt of at least one kind of an oxyacid selected from sulfurous acid and thiosulfuric acid. A dry blend of 0.6 g aluminum sulfate and 30 g polymer is prepared in Example for Comparison 3 of the patent, and is shown to have a blocking of 70 percent or more after 5 minutes.
U.S. Pat. No. 5,578,318 discloses the preparation of superabsorbent xe2x80x9chydrophobic coated particlesxe2x80x9d by dry blending materials, such as non-crosslinked polyacrylate salts, with a source of multivalent ions and, optionally, then adding an alcohol, certain wetting agents, and polysiloxane derivatives. The wetted material is dried prior to use. Example XXIII of this patent discloses a blend of 2.61 weight percent AQUALON A-250, 0.21 weight percent aluminum acetate, and 97.18 weight percent water. After drying, the resulting material of this example exhibited relatively poor performance as a superabsorbent.
U.S. Pat. No. 4,090,013 discloses materials prepared from a water-soluble anionic polyelectrolyte and a polyvalent metal cation source. However, the products are characterized in U.S. Pat. No. 5,578,318 as exhibiting gel blocking.
U.S. Pat. No. 4,693,713 discloses an absorbent for blood and serous bodily fluids, the absorbent comprising a physical mixture of certain polymers and certain compounds. The compounds are described as water soluble, present in the form of a pourable powder at ambient temperature, and not harmful to health. The patent teaches that the compound may be added to the polymer by dissolving it in the monomer solution, or that the compound can be added to the polymer preparation process at any time in dry or dissolved form. Dry blends of polymer and compound are prepared in the examples of the patent.
The problem of gel blocking has been particularly noted in multilayer absorbent articles. One means of solving this problem has been to incorporate slow-rate polymers into the articles. Several means of producing these have been suggested. However, none of these methods produce a totally satisfactory slow-rate polymer.
It would be desirable to have a process for preparing a superabsorbent polymer having a slow rate of absorption which would not require the use of a cation removal agent or a coating for the polymer. One clear advantage of such a process would be the cost savings associated with eliminating the use of the extra materials.
The present invention includes an improved process for the preparation of superabsorbent polymers having a slow rate of absorption, and the polymers prepared by the process. More specifically, the process is a process for the preparation of water-swellable, water-insoluble polymer particles having a slow rate of water absorption, the process comprising contacting a polyvalent metal salt solution with water-swellable, water-insoluble polymer particles under conditions such that there is formed a polymer having an Absorption Rate Index of at least about 5 minutes. The polymer of the invention is a water-swellable, water-insoluble polymer having a slow rate of absorption, the polymer being cross-linked with a covalent crosslinking agent and the metal of a polyvalent metal salt such that the Absorption Rate Index of the polymer is at least about 5 minutes. In another embodiment, the present invention includes articles containing the slow rate superabsorbent polymer.
A preferred process for preparing the improved water-swellable, water-insoluble polymer of the invention involves contacting a covalently crosslinked superabsorbent polymer with a polyvalent metal salt solution under conditions such that there is formed a polymer having an Absorption Rate Index of at least about 5 minutes.
The term xe2x80x9cAbsorption Rate Indexxe2x80x9d (ARI) refers to the Absorption Rate Index as measured according to the ARI Test Method described hereinbelow.
In the present invention, a polyvalent metal salt advantageously is employed in an amount sufficient to produce a polymer having an Absorption Rate Index which is at least about 5 minutes. The polyvalent metal salt is preferably water soluble. Examples of preferred metal cations include the cations of Al, Fe, Zr, Mg and Zn. Preferably, the metal cation has a valence of at least +3, with Al being most preferred. Examples of preferred anions in the polyvalent metal salt include halides, chlorohydrates, sulfates, citrates, nitrates and acetates, with chlorides, sulfates, citrates, chlorohydrates and acetates being preferred, citrates, chlorohydrates and sulfates being more preferred, and citrates being most preferred. Highly water soluble salts of aluminum are preferred. Aluminum citrate is the most preferred polyvalent metal salt and is commercially available. Mixtures of polyvalent metal salts can be employed. Preferably, at least 0.003 mole of metal ion per mole of carboxyl groups is employed. More preferably, at least about 0.016 mole of metal ion per mole of carboxyl groups, and most preferably at least about 0.03 mole of metal ion per mole of carboxyl groups, is employed. Preferably, no more than 0.1 mole of metal ion per mole of carboxyl groups is employed based on the weight of the polymer. More preferably, no more than about 0.086 mole of metal ion per mole of carboxyl groups and most preferably no more than 0.07 mole of metal ion per mole of carboxyl groups is employed. Preferably, the amount of polyvalent metal salt employed is from 0.003 to 0.1 mole of metal ion per mole of carboxyl groups. More preferably, from 0.016 to 0.086 mole metal ion per mole of carboxyl groups is employed, and most preferably from 0.03 to 0.07 mole metal ion per mole of carboxyl groups is employed.
The water-swellable, water-insoluble, hydrophilic polymer suitably employable in the present invention can be any hydrophilic polymer which is capable of absorbing large quantities of fluids. These polymers are well known in the art and are widely commercially available. In particular, water-absorbent polymers useful in this invention are water-absorbent polymers which contain carboxyl moieties. Preferably, at least about 0.01 equivalent of carboxyl groups are present per 100 grams of the water-absorbent resin. Among preferred carboxyl-containing water absorbent polymers are hydrolyzates of starch-acrylonitrile graft copolymers, partially neutralized products of starch-acrylic acid or polyvinyl alcohol graft copolymers, saponification products of vinyl acetate acrylic ester copolymers, derivatives of copolymers of isobutylene and maleic anhydride, hydrolyzates of acrylonitrile copolymers, crosslinked products of hydrolyzates of acrylonitrile copolymers, crosslinked carboxymethyl cellulose, polyaspartate hydrolyzates of acrylamide copolymers, crosslinked products of hydrolyzates of acrylamide copolymers, partially neutralized products of polyacrylic acids and crosslinked products of partially neutralized polyacrylic acids. The base polymer for use in this invention suitably has an absorption capacity of from 20 g/g to 50 g/g, although polymers having an absorption capacity outside this range can also be employed.
Examples of some suitable water-swellable, water-insoluble polymers and processes, including gel polymerization processes, for preparing them are disclosed in U.S. Pat. Nos. 3,997,484; 3,926,891; 3,935,099; 4,090,013; 4,093,776; 4,340,706; 4,446,261; 4,683,274; 4,459,396; 4,708,997; 4,076,663; 4,190,562; 4,286,082; 4,857,610; 4,985,518; and 5,145,906, which are incorporated herein by reference. In addition, see Buchholz, F. L. and Graham, A. T., xe2x80x9cModern Superabsorbent Polymer Technology,xe2x80x9d John Wiley and Sons (1998). Such hydrophilic polymers are prepared from water-soluble xcex1,xcex2-ethylenically unsaturated monomers such as monocarboxylic acids, polycarboxylic acids, acrylamide and their derivatives.
The contacting of the base polymer with the polyvalent metal salt solution can be conducted in any suitable manner. The contacting conditions are those which are sufficient to produce a polymer having an ARI of at least 5 minutes. The preferred process of the invention involves soaking a superabsorbent polymer in a solution of a polyvalent metal salt. The soaking time for diffusion of the polyvalent metal salt into the polymer suitably can range from less than 1 hour up to 72 hours or more. It is preferred that the soaking step be at least 1 hour in length. The soaking step may also be conducted for a period of greater than 2 hours, greater than 3 hours, greater than 4 hours, greater than 5 hours, greater than 16 hours, or longer. The temperature at which the gel is maintained during diffusion of the aluminum salt into the polymer suitably is 10xc2x0 C. to 150xc2x0 C. The water ratio may range from 1 to 10 parts of water per part of base polymer. Preferably, the contacting of the polymer and polyvalent metal salt is conducted in the substantial absence of a monovalent metal salt or ammonium salt of at least one kind of an oxyacid selected from sulfurous acid and thiosulfuric acid. In a preferred embodiment, the contacting is conducted in the substantial absence of divalent metal salts, and in another preferred embodiment the contacting is conducted in the substantial absence of alcohols. Preferably, the contacting is conducted in the absence of cellulosic fibers, and in the absence of the xe2x80x9ccation removal agentsxe2x80x9d of U.S. Pat. No. 4,548,847, the teachings of which are incorporated herein by reference.
In a preferred process of the invention, the polymer which has been contacted with the solution of polyvalent metal salt preferably is dried following the contacting step. Preferably, the wetted particles are dried at a temperature of at least about 100xc2x0 C., more preferably at least 120xc2x0 C. Suitable drying means include fluidized bed driers, rotary driers, forced air ovens and through-circulation band dryers. In some instances, drying can occur in two or more stages, that is, multi-stage drying. Following the completion of drying, the polymer is further sized to form particles preferably having an average diameter less than about 2 mm and more preferably less than about 1 mm. Preferably, the final polymer product has an average particle size of at least 160 microns.
The dried polymer optionally can be heat treated, and the method of heat treatment is not critical. For example, forced air ovens, fluidized bed heaters, heated screw conveyors, and the like may be successfully employed. If desired, the heat-treated polymer may be remoisturized for ease in handling.
Another optional process step is surface cross-linking, which may improve absorptive properties of the polymer particles. Procedures for surface crosslinking are well known in the art and described in, for example, U.S. Pat. Nos. 4,734,478, and 4,666,983, the teachings of which are incorporated herein by reference. These procedures may increase the modulus and/or the absorbency under load of the polymer particles.
The composition of the invention can optionally include other additives such as, for example, anticaking agents. Anticaking agents are well-known. Silica is an example of a preferred anticaking agent.
The composition of the invention exhibits a slow rate of absorbency. Preferably, the composition has an Absorption Rate Index of at least about 5 minutes, more preferably at least about 10 minutes, even more preferably at least about 20 minutes and most preferably at least about 30 minutes. Preferably, the polymer of the invention has reversible cationic crosslinks. Preferably, the polymer of the invention has the metal of the polyvalent metal salt distributed essentially homogeneously distributed throughout the polymer. Preferably, the polymer of the invention is not coated.
The superabsorbent polymers of this invention are useful in the manufacture of moisture absorbent articles, such as disposable diapers, sanitary napkins, incontinence garments and bandages. The superabsorbent compositions of this invention are particularly useful in the manufacture of thin and ultra thin disposable diapers which have excellent moisture absorbence capacity, fluid distribution properties and reduced leakage. For example, the superabsorbent polymers of this invention can be used in the manufacture of absorbent articles such as those described in U.S. Pat. Nos. 3,669,103; 3,670,731; 4,654,039; 4,430,086; 4,973,325; 4,892,598; 4,798,603; 4,500,315; 4,596,567; 4,676,784; 4,938,756; 4,537,590; 4,673,402; 5,061,259; 5,147,343; and 5,149,335; the teachings of which are hereby incorporated by reference. Construction of diapers and other absorbent articles is well known, and materials useful as fluff in absorbent articles are also well known. For the purposes of the present invention, the term xe2x80x9cfluffxe2x80x9d is given its meaning as understood by those of ordinary skill in the art. Examples of fluff include cotton fibers, curly fibers, wood pulp fibers, synthetic fibers, or a combination thereof, which are formed into a pad and absorb primarily by capillary attraction mechanism. See, e.g., U.S. Pat. No. 4,610,678.
In making absorbent articles with the compositions of this invention, the superabsorbent composition may be mixed with, attached to, layered in, or dispersed in a porous matrix of fibers. Such matrices are made with hydrophilic fibers such as wood pulp or fluff, cotton linters, and synthetic fiber""s or a mixture of the fibers and the wood fluff. The fibers can be loose or joined, as in nonwovens. Examples of synthetic fibers include those made using polyethylene, polypropylene, polyesters, and copolymers of polyesters and polyamides. The synthetic fibers may be meltblown fibers or fibers which have been treated to render them hydrophilic.
The superabsorbent polymers of this invention are even more advantageously utilized in absorbent structures that incorporate superabsorbent polymers having a slow absorption rate, either alone or in tandem with superabsorbent polymers having different absorption rates, in multi-compartmentalized or multi-layered structures. Examples of such structures are described in U.S. Pat. Nos. 4,338,371; 4,935,022; 5,364,382; 5,429,629; 5,486,166; 5,520,673; 5,531,728; 5,562,646; and 5,728,082, the teachings of which are incorporated herein by reference.
The superabsorbent polymers of this invention are also advantageously used in those absorbent article manufacturing processes where contact with aqueous fluids is inherent to the process. In these processes, slow absorption rate helps to prevent excessive superabsorbent swelling, which swelling results in large amounts of water to be removed and large volume changes occurring upon drying. Examples of such processes are wet-laid composite processes, and processes for making foam absorbent structures. Examples of wet-laid composite processes are described in U.S. Pat. Nos. 4,354,901; 4,986,882; 5,300,192; 5,308,896; 5,538,783; 5,543,215; 5,795,439 and 5,651,862, the teachings of which are incorporated hereby reference. Examples of foam absorbent structures are described in U.S. Pat. Nos. 4,990,541 and 5,011,864.
Absorbent articles, such as disposable diapers, typically are made with a liquid-impermeable backing material, a liquid-permeable bodyside facing material and the liquid-absorbing composite sandwiched between the backing material and the facing material. The liquid-impermeable backing material can be made from commercially available polyolefin film and the liquid-permeable facing material can be made from a commercially available nonwoven material, such as spunbonded or corded fibrous web which is wettable and capable of passing urine.
The absorbent articles of the invention may comprise from 5 percent to 95 percent by weight of the superabsorbent polymers of the invention. In a typical absorbent article, the superabsorbent polymer of the invention can be dispersed in a fiber matrix; in such an article the superabsorbent advantageously is present in an amount from about 30 to 70 weight percent based on the weight of the article and the fiber matrix is present in an amount of from about 70 to 30 weight percent based on the weight of the article. In another form of absorbent article, the superabsorbent may be present in a containment structure in which the superabsorbent polymer is present in an amount of about 30 to 95 percent by weight. Combinations of dispersed superabsorbent polymer and contained superabsorbent polymer are also known.
The following examples and comparative experiments are given to illustrate the invention and should not be construed as limiting its scope. All parts and percentages are by weight unless otherwise indicated.
The absorption capacity (AC) is measured according to the method stated in Buchholz, F. L. and Graham, A. T., xe2x80x9cModern Superabsorbent Polymer Technology,xe2x80x9d John Wiley and Sons (1998), page 153.
Homogeneous distribution of the metal of the metal salt of the invention in the superabsorbent polymer is measured according to the electron microprobe analysis method as described at Buchholz, F. L. and Graham, A. T., id. at pages 57-58.
ARI Test Method: Method for Determination of the Absorption Rate Index
A 100 mL graduated cylinder is filled with 100 mL of 0.9 wt % aqueous saline solution. A superabsorbent polymer sample is screened to xe2x88x9230/+50 mesh using ASTME-11 specification screens to give a sample having particles in the range of 300 to 600 microns. A 1.00 g portion of the screened polymer is dumped into the graduated cylinder. When the sample first reaches the bottom of the graduated cylinder, a timer accurate to the nearest second is started. The volume of the gel layer is measured at times of 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 15, 30, 60, 90, 180, 330 and 480 minutes. The data is plotted and the time required for the gel volume to reach 60% of its value at 8 hours is determined by interpolation. This time is reported as the t60 time, and for the purposes of the present invention is the xe2x80x9cAbsorption Rate Index.xe2x80x9d


Catalyst precursor compounds having both (i) a polydentate ligand which comprises a cyclic moiety as well as a heteroatom and (ii) a protected hydride/hydrocarbyl ligand bonded to a metal atom, as well as olefin polymerization catalyst systems based thereupon, polymerization processes using such catalyst systems and polymers produced thereby.

The present invention relates to catalyst precursor compounds having both (i) a polydentate ligand which comprises a cyclic moiety as well as a heteroatom and (ii) a protected hydride/hydrocarbyl ligand linked to a metal atom, to olefin polymerization catalyst systems based thereupon, to polymerization processes using such catalyst systems, and to polymers produced thereby.
The intense commercialization of metallocene polyolefin catalysts has led to widespread interest in the design of non-metallocene, homogeneous catalysts. This field is more than an academic curiosity as new, non-metallocene catalysts may provide an easier pathway to currently available products and may also provide product and process opportunities which are beyond the capability of metallocene catalysts. In addition, certain non-cyclopentadienyl ligands may be more economical due to the relative ease of synthesis of a variety of substituted analogs.
Thus there is a need in the art for new olefin polymerization catalysts and the polymers they produce. This invention identifies a new family of catalysts that can be used to produce polyolefins, particularly polyethylenes.
WO 97/02298, WO 96/33202 and Fuhrmann et al, Inorg. Chem. 35:6742-6745 (1996), each fully incorporated herein by reference, all disclose nitrogen containing single site like catalyst systems.
WO 99/01460, fully incorporated herein by reference, discloses the use of transition metal compounds comprising bidentate ligands containing pyridine or quinoline moieties and mixtures thereof with activators to polymerize olefins. For example, [[1-(2-pyridyl)N-1-methylethyl]-[1-N-2,6-diisopropylphenylamido]]zirconium tribenzyl is combined with modified methyl alumoxane in the gas phase to produce ethylene/hexene copolymers.
Furthermore, U.S. Pat. No. 6,187,712 B1, fully incorporated herein by reference, discloses a catalyst composition for the polymerization of olefins that comprises a mono- or biscyclopentadienyl catalyst precursor comprising at least one protected hydride and/or protected hydrocarbyl ligand such as tetrahydroborate bound to a metal atom. A typical example of a catalyst precursor disclosed in the patent is methylcyclopentadienylzirconium tris(tetrahydroborate).
It has now been found that transition metal compounds comprising both polydentate, heteroatom containing ligands and protected hydride and/or hydrocarbyl ligands combined with a cocatalyst can effectively catalyze the polymerization of olefins.
The present invention provides catalyst precursor compound represented by MXxYyZz wherein M is a metal selected from Groups 3 to 12 and the lanthanide and actinide series of the Periodic Table of Elements. X represents an anionic moiety of the formula AR4, where A represents a Group 13 element, the radicals R are independently selected from carbon containing groups and hydrogen. Also, two radicals R may be combined to form a ring structure together with A. Moreover, at least one of the radicals R bridges A and M. Y is an at least bidentate anionic group represented by (T)txe2x80x94Dxe2x80x94(E)exe2x80x94G wherein D is selected from elements of Groups 13 to 16 and is bonded to M. G is a 3- to 30-membered mono- or polycyclic radical and comprises, and is bonded to M through, a heteroatom Q which either is a ring member or is covalently bonded to a ring member. Furthermore, E bridges D and G and may additionally be bonded to M, whereas T is a radical comprising 1 to 50 non-hydrogen atoms. e is 0 or 1 and t is 0 or an integer sufficient to satisfy the valence of D. Z is a monovalent, divalent or trivalent anion different from X and Y. x is an integer of from 1 to 6 inclusive, y is an integer of from 1 to 3 inclusive and z is 0 or a positive integer, provided that x times the valence of X plus y times the valence of Y plus z times the valence of Z equals the valence of M.
The present invention also provides a catalyst system which includes the catalyst compound, for polymerization processes utilizing the catalyst system, and for polymers produced therefrom.
For the purposes of this patent specification, the term xe2x80x9ccatalystxe2x80x9d refers to a metal compound, that when combined with an activator, polymerizes olefins. The term xe2x80x9cactivatorxe2x80x9d is used interchangeably with the term xe2x80x9cco-catalystxe2x80x9d, and the term xe2x80x9ccatalyst systemxe2x80x9d refers to the combination of a catalyst, an activator, and optionally a support material.
In one embodiment, the new catalyst compounds of the present invention may be represented by Formula I:
MXxYyZzxe2x80x83xe2x80x83Formula I
In Formula I, M is a metal selected from Groups 3 to 12 and the lanthanide and actinide series of the Periodic Table of Elements. In one embodiment, M is selected from Groups 3 to 10 and the lanthanides. Illustrative, non-limiting examples of M are Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ni, Co, Fe, Pd, Ce, Y and Sm. Preferably, M is selected from Groups 4, 5, 6 and the lanthanides, in particular from Groups 4 and 5. Preferably, M is a Group 4 element, preferably zirconium or hafnium, and most preferably M is zirconium.
In Formula I, X represents a anionic moiety having the formula AR4 where at least one of the radical groups, R, bridge A and M and where A is selected from Group 13 elements such as, e.g., B, Al and Ga. Preferably, A represents B or Al, and most preferably B. The radicals R, may be the same or different from each other, and are independently be hydrogen or a C1-20 hydrocarbyl radical. Preferably, each R is independently hydrogen, an alkyl group, for example methyl or ethyl, or an aryl group, for example phenyl. More preferably at least one, and even more preferably at least two of the radicals R are hydrogen. Most preferably three or four of the radicals R are hydrogen.
Moreover, in compounds of Formula I the two radicals R and A together may form a ring having 3 to 10 ring members, preferably 4 to 8 members. While for values of x of 2 and higher the radicals X in Formula I may be identical or different, they are preferably identical.
In a preferred embodiment, AR4, represented by each X in Formula I, is independently tetrahydroborate or tetrahydroaluminate. Most preferably each radical X is tetrahydroborate.
In Formula I, Y is an at least bidentate anionic group represented by Formula II:
(T)t-Dxe2x80x94(E)e-Gxe2x80x83xe2x80x83Formula II
Where D is bonded to M of Formula I, and is selected from elements of Groups 13 to 16 of the Periodic Table of Elements. Illustrative, non-limiting examples of atoms D are B, C, Si, N, P, O and S. Preferably D is selected from N and P. Most preferably, D is nitrogen.
In Formula II, G is a mono- or polycyclic (e.g., bicyclic or tricyclic) radical, containing a heteroatom Q. G is bonded to M through the heteroatom Q which is either a ring member or is covalently bonded to a ring member. G contains at least 3, preferably at least 5, and most preferred at least 6 ring members. The maximum number of ring members of G is about 30, more preferred about 20, and most preferred about 10. Preferably G is not more than bicyclic, and most preferred it is monocyclic. If the ring system is polycyclic, it preferably comprises fused rings. In another embodiment, G is an aromatic ring system or fused ring system or at least comprises an aromatic ring. G may contain additional heteroatoms as ring members and/or covalently bonded to the ring other than Q. Preferably Q is a ring member and is N, O, P or S, more preferably N or P and most preferably N. In one embodiment, at least one of D and Q is N. In a particularly preferred embodiment D and Q are both nitrogen atoms. If Q is bonded to a ring member, this ring member usually is a carbon atom. Illustrative, non-limiting examples of GQ are pyridyl, pyrazyl and quinolyl, with pyridyl being particularly preferred.
In addition to optionally comprising more than one heteroatom as a ring member or covalently bonded to a ring member, G may also carry one or more (e.g., 2, 3, 4 etc.) substituents in any position of the ring(s) thereof. Illustrative, non-limiting examples of preferred substituents are linear, branched and cyclic alkyl and alkenyl, alkoxy, aryl, alkylaryl, arylalkyl and aryloxy radicals.
E, if present (i.e., e in Formula II equals 1), bridges D and G. If Q is a ring member, E preferably connects D and an atom different from Q, for example, a ring atom adjacent to Q. The number of atoms belonging to E and separating D from G usually is such that the ring structure formed by M, one or more atoms of G, E and D has at least 4, preferably at least 5 members, and not more than 8, preferably not more than 7, and most preferred not more than 6 ring members. Usually at least one of the atoms of E which connects D and G is selected from elements of Group 14, in particular C and Si. In addition to being bonded to G and D, E may also be bonded to M. Moreover, one or more atoms of E and one or more atoms of G together may form an additional ring structure, for example a ring fused with G. Additionally or alternatively, one or more atoms of E may form a ring together with D and, optionally, with one or more atoms of T. If present, the rings formed by E or parts thereof and G or parts thereof and the rings formed by E or parts thereof and D and, optionally, T and parts thereof usually have not more than 8 ring members, preferably not more than 7 ring members, most preferred not more than 6 ring members. Furthermore, these rings may be unsaturated or even (hetero)aromatic.
Non-limiting examples of E include groups of the formulae (CR1R2), (Cxe2x95x90CR1R2) and (SiR1R2) wherein R1 and R2 are independently selected from hydrogen and C1-C20 hydrocarbyl groups, in particular C1-C10 hydrocarbyl groups such as, e.g., alkyl and aryl groups. R1 and R2 may be the same or different from each other. Preferred radicals R1 and R2 are hydrogen, methyl, ethyl, propyl and phenyl, with methyl being particularly preferred. Further illustrative, non-limiting examples of E include groups of the formulae xe2x80x94CR1xe2x95x90CR2xe2x80x94 and xe2x80x94CR1R2xe2x80x94SiR1R2xe2x80x94 wherein R1 and R2 have the meanings given above.
In Formula II, T is a radical comprising 1 to 50 non-hydrogen atoms. Preferably T comprises at least 2, more preferred at least 4, and most preferred at least 6, non-hydrogen atoms whereas the maximum number of non-hydrogen atoms included in T usually does not exceed 40, preferably not exceed 30 and most preferred not exceed 20. Usually at least one of these non-hydrogen atoms is carbon and preferably at least 50%, most preferred at least 75% and up to 100%, of these non-hydrogen atoms are carbon atoms. Of course, hydrogen atoms may also be (and preferably are) present in T. Preferred examples of T include unsubstituted and substituted C1-C20 hydrocarbyl groups (such as, e.g. C6-C20 hydrocarbyl groups) and tri(C1-C20 hydrocarbyl)silyl groups (e.g., tri(C1-C6 alkyl)silyl groups) and combinations thereof. Even more preferred examples of T include groups which comprise at least one cyclic or heterocyclic radical, for example, substituted aryl and heteroaryl groups. Usually these groups comprise 5 to 20 (e.g., 6 to 10) ring members. Preferred aryl and heteroaryl groups carry at least one and, even more preferred, two substituents in ortho position with respect to D (in addition to one or more optional meta- and/or para-substituents). These one or two ortho-substituents may, for example, be halogen atoms (e.g., Cl, Br), C1-C20 hydrocarbyl groups (e.g., C3-C20 alkyl and C6-C1 aryl, alkylaryl or arylalkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, phenyl, benzyl, tolyl, xylyl and naphthyl) and tri(C1-C20 hydrocarbyl)silyl groups (preferably trialkylsilyl groups such as trimethylsilyl radicals). If two ortho-substituents are present, they are preferably identical. Furthermore, if T comprises a heteroaryl moiety, this moiety preferably comprises one or more heteroatoms independently selected from O, N and S. Particularly preferred examples of T are phenyl groups carrying two ortho-substituents selected from isopropyl, isobutyl, sec-butyl, tert-butyl, phenyl, benzyl, tolyl, naphthyl and trimethylsilyl radicals. The most preferred ortho-substituent is isopropyl.
If two or more groups T are present, they are preferably identical. However for t=0, T is absent (e.g., for D=oxygen). In preferred embodiments of the compound of Formula I not more than two and, most preferred, only one group T is present in the group of Formula II (e.g., for D=N).
In Formula II, Z represents a monovalent, divalent or trivalent anion that is bonded to M and is different from X and Y. If two or more anions Z are present, they may be identical or different. Illustrative, non-limiting examples of Z are halogen, alkyl, aryl, alkenyl, alkylaryl and arylalkyl radicals having 1-20 carbon atoms (optionally bonded to M through an oxygen atom). Further non-limiting examples of Z are amide, phosphide, sulfide, silylalkyl, diketonate, and carboxylate groups. Preferably Z is selected from halogen, alkyl and arylalkyl radicals. Moreover, it is to be noted that the presence of Z in the compounds of the present invention is optional.
The values of x, y and z in Formula I are such that a neutral compound results. Furthermore, in particularly preferred compounds of Formula I, y=1 and z=0, particularly if Y is a bidentate ligand and M is a Group 4 element.
In a particularly preferred embodiment the catalyst precursor compound of the invention is represented by the formula MXxYy where M is titanium, zirconium or hafnium and X represents an anionic moiety of the formula BR4, where two of the radicals R represent hydrogen and the remaining radicals R are independently C1-C10 hydrocarbyl groups or hydrogen atoms and at least one of the radicals R bridges B and M. Also, two radicals R may be combined to form a ring structure together with B. In this preferred embodiment, Y is an at least bidentate anionic group of the formula Txe2x80x94Nxe2x80x94Exe2x80x94G wherein N is bonded to M, G is a 5- to 20-membered mono- or bicyclic radical comprising a ring member Q which is selected from N, O, S and P and connects G to M, and E represents (CR1R2), (Cxe2x95x90CR1R2) and (SiR1R2), with R1 and R2 being aliphatic and/or aromatic C1-C10 groups. T is an aryl or heteroaryl group having at least one substituent in ortho position with respect to D, the at least one substituent being selected from C3-C20 alkyl, C6-C10 aryl and trialkylsilyl groups. Furthermore, x is an integer of from 1 to 4 inclusive and y is 1 or 2, provided that x times the valence of X plus y times the valence of Y equals the valence of M. In an even more preferred embodiment, M is zirconium, X represents BH4, G is pyridyl, E is C(CH3)2, T is 2,6-diisopropylphenyl, x is 3 and y is 1.
Unless otherwise stated, a reference to a compound or component includes the compound or component by itself, any of its individual stereoisomers and any mixtures thereof, as well as any combination with other compounds or components, such as mixtures of compounds.
As utilized herein, the following terms have the meanings indicated below.
The term xe2x80x9calkylxe2x80x9d, means a straight-chain, branched-chain or cyclic alkyl radical. Examples of such radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, 2-ethylhexyl, octyl, cyclopentyl, cyclohexyl and the like. The cyclic alkyl radicals may be substituted with one or more straight-chain and/or branched-chain alkyl radicals (i.e., may be alkylcycloalkyl radicals such as, e.g., methylcyclohexyl etc.). Conversely, the straight-chain and branched-chain alkyl radicals may be substituted with one or more cyclic alkyl radicals (i.e., may be cycloalkylalkyl radicals such as cyclohexylmethyl etc.). Moreover, unless indicated otherwise, the above alkyl radicals may be substituted by one or more groups preferably and independently selected from halogen (e.g., F, Cl, Br), alkoxy (e.g., methoxy, ethoxy, propoxy, butoxy and the like), hydroxy, amino, monoalkylamino (e.g., methylamino, ethylamino, propylamino and the like) and dialkylamino (e.g., dimethylamino, diethylamino, dipropylamino, diisopropylamino, piperidino and the like) and trihydrocarbylsilyl (e.g., trimethylsilyl, triphenylsilyl and the like). Unless otherwise stated, the above definition of the term xe2x80x9calkylxe2x80x9d also applies to groups which comprise one or more alkyl radicals.
Preferred alkyl groups are linear and branched groups having 1 to 8, particularly 1 to 6, and even more preferred, 1 to 4 carbon atoms (such as, e.g., methyl, ethyl, propyl and isopropyl). If present, substituents are preferably selected from halogen and alkoxy, more preferred from F, Cl, methoxy and ethoxy, most preferred from F and Cl.
The term xe2x80x9calkenylxe2x80x9d means xe2x80x9calkylxe2x80x9d as defined above having one or more double and/or triple bonds. Examples of alkenyl radicals include, but are not limited to, ethenyl, propenyl, allyl, butenyl, propargyl, 1,4-butadienyl, isopropenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctadienyl and the like. Preferred alkenyl groups are those having 2 to 8, particularly 2 to 6, and even more preferred, 2 to 4 carbon atoms (such as, e.g., vinyl, allyl, and 2-butenyl). If present, substituents are preferably selected from halogen and alkoxy, more preferred from F, Cl, methoxy and ethoxy, most preferred from F and Cl.
The term xe2x80x9calkoxyxe2x80x9d means an alkyl or alkenyl ether radical wherein the terms xe2x80x9calkylxe2x80x9d and xe2x80x9calkenylxe2x80x9d are as defined above. Examples of suitable alkyl ether radicals include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, iso-butoxy, sec-butoxy, tert-butoxy, allyloxy, trifluoromethoxy and the like. Preferred alkoxy groups are methoxy and ethoxy.
The term xe2x80x9carylxe2x80x9d means an aromatic radical, for example, a phenyl, naphthyl, phenanthryl or anthracenyl radical and the like which optionally carries one or more identical or different substituents, for example, alkoxy, aryl, halogen, hydroxy, amino, monoalkylamino, dialkylamino, nitro, trihydrocarbylsilyl, alkyl-CO, alkylsulfonyl, alkyl-OCO etc., these terms being as defined herein. Illustrative, non-limiting examples of aryl radicals are phenyl, naphthyl, fluorenyl, chlorophenyl, dichlorophenyl, fluorophenyl, perfluorophenyl, hydroxyphenyl, anisyl, biphenyl, nitrophenyl, acetylphenyl, aminophenyl, and the like. Unless otherwise stated, the above definition of the term xe2x80x9carylxe2x80x9d also applies to groups which comprise one or more aryl radicals. For example, the term xe2x80x9caryloxyxe2x80x9d means an aryl ether radical wherein the term xe2x80x9carylxe2x80x9d is as defined above. Preferred aryl groups contain 6 to 12, more preferred 6 to 10 carbon atoms, such as, e.g., phenyl, naphthyl and biphenyl. Preferred aryloxy groups are phenoxy and naphthoxy.
The term xe2x80x9calkylarylxe2x80x9d means an aryl radical carrying at least one alkyl and/or alkenyl radical as ring substituent, the terms xe2x80x9carylxe2x80x9d, xe2x80x9calkylxe2x80x9d and xe2x80x9calkenylxe2x80x9d being as defined above. Illustrative, non-limiting examples of alkylaryl groups are tolyl, xylyl, mesityl, ethylphenyl, trifluoromethylphenyl, vinylphenyl, cumyl and the like.
The term xe2x80x9carylalkylxe2x80x9d means an alkyl radical carrying at least one aryl group wherein the terms xe2x80x9carylxe2x80x9d and xe2x80x9calkylxe2x80x9d are as defined above, provided that the aryl radical may have one or more alkyl substituents. Illustrative, non-limiting examples of arylalkyl groups are benzyl, phenethyl, diphenylmethyl, tolylmethyl, naphthylmethyl and the like. Preferred examples of arylalkyl and alkylaryl groups include benzyl, phenethyl, tolyl and xylyl.
The term xe2x80x9chalogenxe2x80x9d means fluorine, chlorine, bromine and iodine. Preferred halogens are fluorine, chlorine and bromine.
The term xe2x80x9chydrocarbylxe2x80x9d encompasses alkyl, alkenyl, arylalkyl and alkylaryl groups as defined above. Preferred hydrocarbyl groups comprise 1 to 20, more preferred 1 to 10, and most preferred 1 to 6 carbon atoms. Illustrative, non-limiting examples are methyl, ethyl, propyl, benzyl and phenyl.
The catalyst systems of the present invention comprise one or more catalyst precursor compounds described above and at least one activator or co-catalyst. The activator may be any known catalyst activator and may include an alkyl aluminum compound, an alumoxane, a modified alumoxane, a non-coordinating anion, a Lewis acid, a borane or a mixture thereof.
There are a variety of methods for preparing alumoxanes and modified alumoxanes, illustrative, non-limiting examples of which are described in U.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031, 5,391,793, 5,391,529, 5,693,838, 5,731,253 and 5,731,451 and European publications EP-A-0 561 476, EP-B1-0 279 586 and EP-A-0 594-218, and PCT publication WO 94/10180, all of which are filly incorporated herein by reference. Methylalumoxane (MAO), modified methylalumoxane (MMAO), and trisobutylalumoxane are among the preferred cocatalysts.
Ionizing compounds which give rise to noncoordinating anions may contain an active proton, or some other cation associated with, but not coordinated to or only loosely coordinated to the remaining ion of the ionizing compound. Such compounds and the like are described in European publications EP-A-0 570 982, EP-A-0 520 732, EP-A-0 495 375, EP-A-0 426 637, EP-A-500 944, EP-A-0 277 003 and EP-A-0 277 004, and U.S. Pat. Nos. 5,153,157, 5,198,401, 5,066,741, 5,206,197, 5,241,025, 5,387,568, 5,384,299 and 5,502,124 and U.S. patent application Ser. No. 08/285,380, filed Aug. 3, 1994, all of which are filly incorporated herein by reference. Non-limiting examples of further cocatalysts include those described in PCT publication WO 98/07515 (fully incorporated herein by reference) such as tris(2,2xe2x80x2,2xe2x80x3-nonafluorobiphenyl)fluoroaluminate. Combinations of activators are also contemplated by the invention, for example, alumoxanes and ionizing activators in combination, see for example, PCT publications WO 94/07928 and WO 95/14044 and U.S. Pat. Nos. 5,153,157 and 5,453,410 all of which are fully incorporated herein by reference. Methods of activation such as using radiation and the like are also contemplated as cocatalysts for the purposes of this invention.
Illustrative, non-limiting examples of preferred cocatalysts are the following: tris(2,2xe2x80x2,2xe2x80x3-nonafluorobiphenyl)fluoroaluminate, alumoxane (e.g., MAO and MMAO), triphenyl boron, triethyl boron, tri-n-butyl ammonium tetraethylborate, triaryl borane, tetrakis(pentafluorophenyl) borate salts (such as, e.g., tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate), trisperfluorophenyl boron, diethylaluminum chloride and diisobutylaluminum chloride.
When the cocatalyst is an aluminum compound such as, e.g., an alumoxane, the ratio of Al to M in the catalyst precursor compound usually is at least about 2:1, preferably at least about 10:1, most preferred at least about 50:1. On the other hand, the ratio Al:M usually is not higher than about 100,000:1, preferably not higher than about 10,000:1, and most preferred not higher than about 2,000:1.
On the other hand, when the cocatalyst is a noncoordinating anion (NCA), the ratio of NCA to M usually is at least about 0.5:1, preferably at least about 1:1, although this ratio usually is not higher than about 10:1, preferably not higher than about 5:1.
The catalyst precursor compound of Formula I may be synthesized by any method known in the art. For example, WO 99/01460, supra, discloses methods to produce these compounds. An exemplary process for making preferred compounds of the present invention comprises the reaction of a tetrahydroborate complex of formula M(BH4)n, where n is the oxidation state of M (prepared, for example, by reaction of the corresponding halide of M with an alkali or alkaline earth tetrahydroborate), with an alkali or alkaline earth metal salt of Y in the desired stoichiometric ratio. Such a process is illustrated in Example 2 below for M=Zr.
In a particularly preferred embodiment of the present invention, the catalyst precursor compound is N-(1-methyl-1-(2-pyridyl)ethyl)-N-(2,6-diisopropylphenyl) amido zirconium tris(tetrahydroborate). In another preferred embodiment, N-(1-methyl-1-(2-pyridyl)ethyl)-N-(2,6-diisopropylphenyl)amido zirconium tris(tetra-hydroborate) is used in combination with an alumoxane, preferably methylalumoxane, more preferably modified methylalumoxane, in a gas or slurry phase reactor to produce polyethylene, preferably high density polyethylene. In another preferred embodiment, a non-coordinating anion, such as tri(n-butyl)ammonium tetrakis(pentafluorophenyl)boron or a compound such as tris(perfluorophenyl)-boron, is used in combination with the N-(1-methyl-1-(2-pyridyl)ethyl)-N-(2,6-diisopropylphenyl)amido zirconium tris(tetrahydroborate) in a gas or slurry phase reactor. In another embodiment that activator is selected from the following: tris(2,2xe2x80x2,2xe2x80x3-nonafluorobiphenyl)fluoroaluminate, methyl alumoxane, triphenyl boron, triethylboron, tri-n-butylammonium tetraethylborate, triaryl-borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)boron, tris(perfluoro-phenyl)boron and diethylaluminum chloride.
One or more of the catalyst components may be supported on an organic or inorganic support. Typically the support can be of any of the known solid, porous supports. Non-limiting examples of typical support materials include talc; inorganic oxides such as silica, magnesium chloride, alumina, silica-alumina and the like; and polymeric supports such as polyethylene, polypropylene, polystyrene and the like. Preferred supports include silica, clay, talc, magnesium chloride and the like. Preferably the support is used in finely divided form. Prior to use the support is preferably partially or completely dehydrated. The dehydration may be done physically by calcining or by chemically converting all or part of the active hydroxyls. For more information on how to support catalysts and catalyst components, respectively, U.S. Pat. No. 4,808,561 (fully incorporated herein by reference) may, for example, be referred to.
If both the catalyst precursor and the cocatalyst are to be supported, the cocatalyst may be placed on the same support as the catalyst precursor or may be placed on a separate support. Also, the components of the catalyst system need not be fed into the reactor in the same manner. For example, one catalyst component may be slurried into the reactor on a support while the other catalyst component may be provided in a solution.
In another embodiment the catalyst system is fed into the reactor in a solution or slurry. Hydrocarbons are useful for the solutions or slurries. For example, the solution or slurry carrier may comprise toluene, hexane, isopentane or a combination thereof such as toluene and isopentane or toluene and pentane. A typical solution would be 0.02 to 0.05 mole catalyst in the hydrocarbon carrier, preferably isopentane or hexane.
In another embodiment the carrier for the catalyst system or its components is a supercritical fluid, such as ethane or propane. For more information on supercritical fluids as catalyst feed agents see EP 0 764 665 A2, fully incorporated herein by reference.
Polymerization Process of the Invention
The catalyst systems described above are suitable for use in a solution, gas or slurry polymerization process or a combination thereof, most preferably a gas or slurry phase polymerization process.
In one aspect, this invention is directed toward solution, slurry or gas phase polymerization reactions involving the polymerization of one or more ethylenically unsaturated monomers (olefins) preferably having 2 to 30 carbon atoms, more preferably 2 to 12 carbon atoms, and most preferably 2 to 8 carbon atoms. Preferred monomers include one or more of ethylene, propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene-1, decene-1 and 3-methyl-pentene-1. Cyclic and aromatic olefins such as cyclohexene, norbornene and styrene may also be used. Other non-limiting examples of suitable monomers include diolefins, for example, conjugated and non-conjugated dienes and polyenes such as norbornadiene, vinyl norbornene and ethylidene norbornene. In one aspect, a homopolymer of ethylene is produced. In another aspect, a copolymer of ethylene and one or more of the monomers listed above is produced.
In another aspect, ethylene and/or propylene are polymerized with at least two different comonomers to form a terpolymer. The preferred comonomers are a combination of alpha-olefin monomers having 4 to 10 carbon atoms, more preferably 4 to 8 carbon atoms, optionally with at least one diene monomer. The preferred terpolymers include combinations such as ethylene/butene-1/hexene-1, ethylene/propylene/butene-1, propylene/ethylene/hexene-1, ethylene/propylene/norbornene and the like.
In yet another aspect, the process of the invention involves the polymerization of ethylene and at least one comonomer having 4 to 8 carbon atoms, preferably 4 to 7 carbon atoms. Particularly, the comonomers are butene-1, 4-methyl-pentene-1, 3-methyl-pentene-1, hexene-1 and octene-1, the most preferred being hexene-1, butene-1 and octene-1.
Typically in a gas phase polymerization process a continuous cycle is employed where in one part of the cycle of a reactor system, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed from the recycle composition in another part of the cycle by a cooling system external to the reactor. Generally, in a gas fluidized bed process for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670, 5,317,036, 5,352,749, 5,405,922, 5,436,304, 5,453,471, 5,462,999, 5,616,661 and 5,668,228, all of which are fully incorporated herein by reference.)
The reactor pressure in a gas phase process usually is at least about 10 psig (69 kPa), preferably at least about 100 psig (690 kPa), more preferred at least about 200 psig (1379 kPa) and most preferred at least about 250 psig (1724 kPa). On the other hand, the reactor pressure usually is not higher than to about 500 psig (3448 kPa), preferably not higher than about 400 psig (2759 kPa), more preferably not higher than about 350 psig (2414 kPa).
The reactor temperature in the gas phase process usually is at least about 30xc2x0 C., preferably at least about 60xc2x0 C., more preferably at least about 70xc2x0 C., while it usually is not higher than about 120xc2x0 C., preferably not higher than about 115xc2x0 C., more preferably not higher than about 110xc2x0 C., and most preferably not higher than about 95xc2x0 C. When high density polyethylene is desired the reactor temperature is typically from about 70 to about 105xc2x0 C.
The productivity of the catalyst or catalyst system in a gas phase system is influenced by the main monomer partial pressure. The preferred mole percentage of the main monomer (for example, ethylene or propylene), preferably ethylene, is from about 25 to about 90 mole percent. Generally, the comonomer partial pressure is in the range of from about 20 psia (138 kPa) to about 300 psia (517 kPa), preferably about 75 psia (517 kPa) to about 300 psia (2069 kPa), which are typical conditions in a gas phase polymerization process. Also in some systems the presence of comonomer can provide an increase in productivity.
Other gas phase processes contemplated by the present invention, by way of non-limiting example, include those described in U.S. Pat. Nos. 5,627,242, 5,665,818 and 5,677,375, and European publications EP-A-0 794 200, EP-A-0 802 202 and EP-B-634 421, all of which are herein fully incorporated by reference.
A slurry polymerization process generally uses pressures in the range of from about 1 to about 50 atmospheres (103 kPa to 5068 kPa) and even greater and temperatures in the range from about 0xc2x0 C. to about 120xc2x0 C. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization diluent medium to which ethylene and comonomers along with catalyst are added. The suspension including diluent is intermittently or continuously removed from the reactor where the volatile components are separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquid diluent employed in the polymerization medium is typically an alkane having from 3 to 7 carbon atoms, preferably a branched alkane. The medium employed should be liquid under the conditions of polymerization and relatively inert. When a propane medium is used the process must be operated above the reaction diluent critical temperature and pressure. Preferably, a hexane or an isobutane medium is employed.
Another aspect of the process of the invention is where the process, preferably a slurry or gas phase process, is operated in the absence of or essentially free of any scavengers, such as triethylaluminum, trimethylaluminum, tri-isobutylaluminum and tri-n-hexylaluminum and diethyl aluminum chloride, dibutyl zinc and the like. This process is described in PCT publication WO 96/08520 and U.S. Pat. No. 5,712,352, which are herein fully incorporated by reference.
In another aspect, the process is run with scavengers. Typical scavengers include trimethyl aluminum, tri-isobutyl aluminum and an excess of alumoxane or modified alumoxane.
The molecular weight distribution (Mw/Mn), flow index, and/or density of the polymer made may, for example, be controlled by altering the reaction temperature and/or the catalyst concentration in the intimately mixed catalyst solution and/or the hydrogen concentration and/or the cocatalyst to transition metal ratio, such as the aluminum/zirconium ratio.
In one aspect, the polyolefin recovered typically has a melt index as measured by ASTM D-1238, Condition E, at 190xc2x0 C. of about 1 g/10 min or less. In another aspect, the polyolefin is ethylene homopolymer or copolymer. The comonomer is preferably a C3 to C20 linear, branched or cyclic monomer, and in one embodiment is a C3 to C12 linear or branched alpha-olefin, preferably propylene, hexene, pentene, hexene, heptene, octene, nonene, decene, dodecene, 4-methyl-pentene-1, 3-methyl pentene-1, 3,5,5-trimethyl hexene-1, and the like.
In another aspect, the catalyst system described above is used to make a high density polyethylene having a density of from about 0.925 to about 0.965 g/cm3 (as measured by ASTM 2839), and/or a melt index of about 1.0 or less g/10 min or less (as measured by ASTM D-1238, Condition E, at 190xc2x0 C.). In another aspect, the catalyst system described above is used to make a polyethylene having a density of from about 0.85 to about 0.924 g/cm3.
In yet another aspect, the polymer produced by the process of this invention has a molecular weight distribution (Mw/Mn) of at least 8, e.g., at least 10, more preferably at least 15,even more preferably at least 20, most preferably at least 30. Mn and Mw are measured by gel permeation chromatography.
The polyolefins of the invention can be made into articles such as, by way of non-limiting example, films, molded articles, sheets, pipes and the like. The films may be formed by any of the conventional technique known in the art including extrusion, co-extrusion, lamination, blowing and casting. The films may be obtained by the flat film or tubular process which may be followed by orientation in an uniaxial direction or in two mutually perpendicular directions in the plane of the film. Particularly preferred methods to form the polymers into films include extrusion or coextrusion on a blown or cast film line.
The polymers produced may further contain additives such as slip, antiblock, antioxidants, pigments, fillers, antifog, UV stabilizers, antistats, polymer processing aids, neutralizers, lubricants, surfactants, pigments, dyes and nucleating agents. Non-limiting examples thereof include silicon dioxide, synthetic silica, titanium dioxide, polydimethylsiloxane, calcium carbonate, metal stearates, calcium stearate, zinc stearate, talc, BaSO4, diatomaceous earth, wax, carbon black, flame retarding additives, low molecular weight resins, glass beads and the like. The additives may be present in the typically effective amounts well known in the art, such as 0.001 weight % to 10 weight %.
For purposes of this specification, when an amount, concentration, or other value or parameter, is given as a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of an upper preferred value and a lower preferred value, regardless whether ranges are separately disclosed. Moreover, the upper and lower values of any two ranges given for a specific parameter are to be understood as also disclosing the ranges formed by combining the lower value of the first range with the upper value of the second range and vice versa.
In the present specification, unless otherwise stated, all percentages, parts, ratios, etc., are by weight.
In order to provide a better understanding of the present invention including representative advantages thereof, the following examples are offered.

Catalyst precursor and olefin polymerization processes