An water based adhesive useful for bottle labeling applications. The adhesive contains styrene maleic anhydride and rosin, and provides a formulation with alkali sensitivity at moderate temperature together with cold water resistance.

This invention relates to aqueous adhesive formulations. More particularly, the invention relates to an aqueous bottle labeling adhesive that is formulated to provide an optimum balance of cold water resistance and label removability.
Ice-proof or cold water resistant labeling adhesives have been used for many years for conditions where extreme humidity resistance and label removal are required, as for example in labeling beer and soda bottles, and some pharmaceuticals. Heretofore, most of these adhesives were based on casein in combination with metallic salts; however, the problems associated with caseins, e.g. cost, availability, variations in quality, etc., instigated searches for casein substitutes, especially those based on low cost, readily available starches.
While starch based adhesives are acceptable for some applications, these adhesives do pose a significant problem when used on returnable/reusable beverage bottles which must be cleaned prior to refilling. Typically bottlers use dilute hot caustic solutions to remove the labels, disinfect and clean the bottles; however, the labels bonded with the starch based adhesives which are formulated to give water resistance often resist removal under these conditions and separate steps must be taken to completely scrub off the labels and any residual adhesive.
The requirement for removability is countered by a requirement that the adhesive remain on the bottle during storage and use, a particularly difficult requirement when the bottles are cooled by immersion in ice water coolers. Thus, while adhesives based on starch and ammonium salts of styrene-maleic anhydride resins exhibit superior ice-proof properties, the bond formed by most of these adhesives is so strong that removal of the label, even upon soaking in hot alkaline water, is difficult or impossible under such conditions and equipment as are used in commercial operations.
Due to the recent ecological pressure which has reversed the trend toward xe2x80x9cnon-returnablexe2x80x9d bottles and reemphasized the need for xe2x80x9creturnablesxe2x80x9d which require removal of the labels prior to reutilization, the inability to remove the labels has made these recently developed adhesives unacceptable for commercial operations.
There is thus a need in the art for an ice-proof adhesive for labels which possesses the optimum balance in properties of being sufficiently cold water resistant to remain on the bottles during use yet may be easily removed or stripped from the bottles to facilitate reutilization.
It has now been found that ice-proof adhesives which possess an optimum balance of water resistance and label removability comprises:
a) water;
b) an effective amount of a water soluble adhesive polymer;
c) at least one styrene maleic anhydride copolymer having a styrene to maleic anhydride ratio of 1:1 to 3:1, said styrene maleic anhydride copolymer being present in an amount sufficient to provide 4.8 to 20 parts styrene maleic anhydride per 100 parts adhesive polymer;
d) 0.5 to 25% by weight of a rosin;
e) sufficient alkali to give a pH within the range of 7 to 11.
The resulting adhesive can form adhesive bonds between a large variety of bonded surfaces in many end uses. Further, the use of such formulations not only possess superior ice water resistance; they can significantly improve the aqueous cleanability of the adhesive materials from manufacturing equipment, application equipment, and end uses.
As an adhesive base for the improved adhesives of the present invention can be either natural or synthetic and may include raw starches or converted or modified starches, or casein as well as conventionally employed synthetic polymers or mixtures thereof. When starches are used, they may be derived from any plant source including corn, potato, sweet potato, wheat, rice, sago, tapioca, waxy maize, sorghum, high amylose corn, etc. may be employed as may the corresponding conversion products as those dextrins prepared by the hydrolytic motion of acid and/or heat, the oxidized starches prepared by treatment with oxidants such as sodium hypochlorite, fluidity or thin boiling starches prepared by enzyme conversion or by mild acid hydrolysis or the corresponding ester or ether starch derivatives. The starches may be used singly or in combination to achieve various final properties in the adhesive composition. The preferred starches are amioca based since these starches, when cooked, have a higher resistance toward pasting up on aging. Raw cornstarch or other starch derivatives may additionally be blended into the mixture for the desired rheological or machining properties.
Suitable synthetic polymers include polyvinyl pyrrolidone, polyacrylic acid derivatives, polyvinyl alcohol, ethylene vinyl acetate polymers and derivatives thereof such as carboxylated or surfactant stabilized ethylene vinyl acetate, vinyl acetate polymers and copolymers such as copolymers of vinyl acetate and butyl acrylate, ethyl hexyl acrylate or dioctyl maleate, polyvinyl acrylate homopolymers, acrylic polymers, styrene butadiene polymers, polyurethanes, neoprene and styrene acrylic polymers.
The adhesive composition generally comprises 20 to 80% by weight of the base polymer, preferably about 25 to 40% by weight.
The term xe2x80x9cstyrene-maleic anhydride resinxe2x80x9d as used herein is also meant to include the corresponding acid functionalities as well as the preformed salts of the resins. In general, the styrene-maleic anhydride copolymers will vary in molar ratio of styrene to maleic anhydride from 1:1 to 3:1. They may vary in molecular weight from 1,600 to 50,000 and may include the respective half ester modifications with alcohols.
The styrene and maleic anhydride can be polymerized to form resins for use in this invention by any conventional polymerization methods. Solution polymerization methods can be employed where the monomers are polymerized in a suitable solvent using as a polymerization catalyst a free-radical catalyst, such as benzoyl peroxide or dicumyl peroxide, at a temperature of about 750 to 300xc2x0 C. or more. Suitable solvents include the aromatic hydrocarbons such as cumene, p-cymene, xylene, toluene and the like.
The partial esters of these styrene-maleic anhydride resins can be prepared for use in this invention in conventional manners from alkanols of about 3 to 20 carbon atoms, preferably from hexanol or octanol. The extent of the half-esterification of the styrene-maleic anhydride copolymer will generally be about 10 to 100%, preferably 20 to 80%. That is, about 5 to 50%, preferably 20 to 40% of the total number of carboxyl groups of the copolymer are esterified with alcohol. The esterification can be effected by simply heating a mixture of the appropriate quantities of sytrene-maleic anhydride copolymer with the alcohol at elevated temperatures, usually about 100xc2x0 to 200xc2x0 C. Preparations of these esters are described in U.S. Pat. Nos. 3,342,787 and 3,392,155.
Among the preferred resins employed in this invention are the styrene-maleic anhydride (SMA) copolymers having a styrene to maleic anhydride ratio of 3:1 and a molecular weight of 1900 and sold under the name SMA 3000A by Arco. A half ester, sold by Arco as SMA 2625A, having a styrene to maleic anhydride ratio of about 2:1, a molecular weight of 1900 and comprising a 50% hexyl half ester modification is also preferred. Another preferred resin has a styrene to maleic anhydride ratio of 1:1, a molecular weight of 50,000 and is available from Monsanto under the tradename Lytron 810.
Also useful herein is the half ester, Scripset 550 from Monsanto, which is available in a powdery form, has a softening temperature of 175-180xc2x0 C. and an acid number of approximately 175. Also useful are Scripset 700 (acid number 95) and Scripset 720 (acid number 270) from Monsanto as well as SMA 2000 (acid number 350) and SMA 3000 (acid number 280) from Elf Ato Chem.
The ratio of the styrene maleic anhydride to starch will generally vary between about 4 and 40 parts styrene maleic anhydride per 100 parts base polymer.
The rosins utilized herein includes wood rosins and hydrocarbon rosins. Rosin and wood rosin materials naturally occur in the olioresin of pine trees. Rosin is typically obtained from exudates of living pine trees, aged stumps and as a byproduct of kraft paper industry. Rosins and wood rosins are a complex mixture of mainly naturally occurring resin acids and fatty acids in varying proportions. The materials are typically pale yellow to dark red to nearly black with a red tint. Wood rosins are soluble in most organic solvents but are insoluble in water. Rosin can be obtained as an unmodified rosin directly from a natural source or can be hydrogenated, dehydrogenated, polymerized, derivatized or other modification. Wood rosins useful in the invention are typically solid or nearly solid at room temperature. An important property of the wood rosin material is that it preferably forms a melt at boiling water temperatures. Accordingly, such rosins will have a melting point up to and including 110.xc2x0 C. Other wood rosins can be used with higher melting points if pressurized reactors are available to increase the boiling point of the aqueous solutions into which the rosin is incorporated.
Hydrocarbon resins are thermoplastic polymers of low molecular weight derived from coal or petroleum sources and from turpentine. The average molecular weights of these resins fall below 2,500 and typically below 2,000. Such hydrocarbon resins typically have softening points between 900 and 140xc2x0 C. and often come in the form of a flake or solid product.
Preferred rosins include wood rosin, tall oil rosin, gum rosin and mixtures thereof. Additional information with respect to hydrocarbon resins, rosin and rosin derivatives can be found in the Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol. 11, pp. 242-262, and Vol. 17, pp. 475-508. If acid rosins are used, it is preferred that they have an acid number of less than 140, most preferably less than 130, as determined by A.S.T.M. D-465. The rosin is generally used in an amount of 0.5 to 25%, preferably 1-10%, most preferably 1-3% by weight.
Bases that can be used in the instant invention to assist in the dissolution of the SMA component can be drawn from two general classes. Each of the classes have special and unique properties that are obtained from the interaction between the base, the rosin and the adhesive composition. While a fixed or permanent alkali can also be used to dissolve the SMA, if used alone it will only give caustic washability and not ice water resistance. If ice water resistance is desired, it must be blended with a volatile base.
A first class of base comprises an alkali metal base or alkaline earth metal base which in aqueous solution can neutralize the acidic moiety in an acidic rosin composition. Such basic compositions include bases derived from alkali metals and alkaline earth metals such as sodium, potassium, magnesium, calcium, and other basic metal compounds. Exemplary compounds include sodium oxide, potassium oxide, magnesium oxide, calcium oxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, calcium carbonate, magnesium bicarbonate, alkali metal borate compounds and their hydrates, sodium phosphate, potassium biphosphate, sodium pyrophosphate, and others. Typical properties for the alkali metal and alkaline earth metal bases of this invention involve at least some water solubility, a pH greater than 7 in a water solutions of the base, and sufficient reactivity to neutralize the acidic rosins of the invention. Such bases when used to neutralize the acidic rosins of the invention provide starch based adhesives that are readily dissolved in neutral, acidic or basic aqueous cleaners.
A second class of bases useful in preparing the adhesives of this invention include volatile nitrogen bases. Such bases include basically reacting compounds, preferably from nitrogen, that can be volatilized through the action of heat or upon exposure to ambient atmosphere. Such bases include ammonia, ammonium hydroxide, methylamine, dimethylamine, triethylamine, ethylamine, diethylamine, triethylamine, ethanolamine, dimethylethanolamine, diethanolamine, triethanolamine, morpholine, and others having a boiling point up to and including about 150xc2x0 F. Preferred volatile nitrogen bases for use in this invention comprise compositions having a vapor pressure at room temperature such that the amine evaporates from the glue line at a rate greater than that of water. Such compounds as they evaporate from the glue line leave the adhesive bond particularly susceptible to aqueous removability. Most preferred base for use in this invention includes ammonia and ammonium hydroxide for reasons of rapid reaction, low cost and ease of volatilization. The use of such volatile amines provides an adhesive that when cured can be resistant to the effects of neutral aqueous solutions but can be rapidly removable in the presence of dilute alkali.
For improved ice water resistance, it is also desirable to use a portion of the alkali in the form of a fixed alkali, that is any alkali which does not volatilize off during drying and therefore does not cause the styrene maleic anhydride salt to revert to an insoluble form on aging. Suitable fixed alkali include sodium potassium, lithium hydroxides and the organic amines such as the mono-, di- or tri-ethanolamines or the isopropanolamines.
It is also desirable to utilize a peptizer, such as urea, formamide, ammonium thiocyanate, acetamide, thiourea and dicyandiamide or mixtures thereof, to prevent instability or pasting up of the finished products on aging. If present, the peptizer is utilized in amount of about 5 to 20% by weight, preferably about 10% by weight.
Defoamers, preservatives, humectants, clay, masking agents, color agents and other modifying agents may be added without affecting the desirable properties of the adhesives of the invention. Thus, modifying agents such as wheat flour, bentonite, etc. may be employed for additional shortness and for machining requirements. Defoamers including tributyl phosphate, preservatives such as phenol, color agents like caramel and plasticizers and hygroscopic agents such as glycols, glycerine, fatty acids, etc. may also be employed as required.
Water is the aqueous solvent preferably employed for forming the liquid adhesive, however other aqueous media may be employed to dissolve the various ingredients, including for example, mixtures of organic solvents and water. The amount of solvent employed in preparing these compositions will vary depending upon the properties such as viscosity, etc. desired in the final product and may easily be determined by the practitioner.
The adhesive compositions of this invention are typically made by combining water, the SMA, and defoamer and mixing for about 10 minutes to disperse the SMA. Peptizers such as urea and dicyadiamide (DICY) are then added and mixed after which the fixed amine base is added if utilized. The base polymer, such as the starch, is then added and mixed until fully dispersed after which the volatile nitrogen base is added to raise the pH and dissolve the SMA. The mixture is cooked at 200xc2x0 F. for 15 minutes and then cooled to about 125xc2x0 F. at which point the rosin is added with any remaining ingredients such as additional synthetic polymers, preservatives, masking agents, etc.,
The viscosity of the final product varies with the adhesive base, the type of label, the labeling machine, its speed and the environmental conditions. Thus, viscosities can range from 10,000 cps to 150,000 cps at 72xc2x0 F. (22xc2x0 C.), however they will generally be within the range of 20,000 cps and 60,000 cps.
Virtually any commonly available label can be used with the adhesive compositions of the invention. Labels typically are prepared from thin sheet-like materials and can be made from a variety of materials including paper, polymer films, foil, metallized films, film to polyester sheets, woven and nonwoven fabrics, and other sheet-like materials. Preferably labels formed of paper, polymer films or metallized polymers are used.

Aqueous adhesive compositions useful as bottle labeling adhesives

National Starch and Chemical Investment Holding Corporation


A combination of a low flexural modulus and low crystallinity polyolefin and a functionalized polyolefin were found to result in an olefin composition with excellent adhesion to metals and polar polymers (e.g. polyesters, polyamides, etc) especially fibers therefrom. When these two polyolefins were added to a thermoplastic vulcanizate (e.g. used to partially or fully replace the semicrystalline polyolefin of a thermoplastic vulcanizate), the thermoplastic vulcanizate was found to have the necessary adhesion to form fiber reinforced thermoplastic vulcanizate.

A polyolefin composition and a thermoplastic elastomer based upon a semi-crystalline polyolefin are described which have improved adhesion to polar polymers including textile fibers and metals including wires. A combination of a low flexural modulus (low crystallinity) polypropylene and a maleic anhydride functionalized polypropylene were found to exhibit excellent adhesion to textile fibers. Incorporation of these two components into a TPE (thermoplastic elastomer) imparts excellent adhesion of the TPE to textile fibers.
Polyolefins and thermoplastic elastomers rich in polyolefins have traditionally had poor adhesion to textile fibers. Experiments with thermoplastic vulcanizates (TPV), a subset of thermoplastic elastomers (TPE), using formulations similar to those of U.S. Pat. Nos. 4,130,534 and 4,130,535 resulted in peel strengths of only 0.5 to 1.0 pounds per linear inch (pli) between the TPV and textile fibers after melt processing the TPV to the textile fibers. The industrial hose and belting markets generally require a peel strength of at least 8 to 12 pli for candidate matrix materials for fiber reinforced hoses and belting. While polyolefins and TPVs from polyolefins have benefits over plasticized polyvinyl chloride resin (in terms of chemical resistance and physical properties after aging) and over crosslinked rubbers (in terms of processability and physical properties after aging) their use with textile fibers has been limited due to low adhesion values (low peel strengths).
U.S. Pat. No. 4,957,968 teaches adhesive thermoplastic elastomer blends comprising a) at least a polyolefin modified by a chemically reactive functional group, b) at least one other polymer, and c) at least one olefinic elastomer.
Typically, when a polymer and a fiber exhibit poor adhesion toward each other, the problem is attributed to poor wetting of the fiber with the polymer or a lack of good interactions between the fiber surface and the polymer. If processing aids are not effective in solving the wetting problem, then different fibers or a different polymer is chosen or a sizing, more interactive with the specific polymer, is applied to the fiber.
A combination of two polymers was found that improves the interaction of polyolefins and/or thermoplastic vulcanizates (TPV) with more polar polymers and metals, especially various textile fibers and metal wires. More polar polymers are defined as those polymers more polar than polyolefins due to the inclusion of heteroatoms such as oxygen or nitrogen in the repeating groups. The first polymer is a low crystallinity polyolefin with a low flexural modulus (tangent) such as from about 5,000 to about 20,000 psi (34.5 to 138 MPa). It is hypothesized that the low flexural modulus helps reduce stress at the bond line between the polyolefin and the fiber and/or polar polymer. The first polymer may be characterized as a polyolefin polymer or copolymer with only 10 to 30 percent crystallinity. As described later the first polymer with low crystallinity and a low modulus may be a blend (reactor blend, physical blend, etc.) of a very low crystallinity polymer with a conventional semi-crystalline polyolefin. The second polymer is a functionalized polyolefin (e.g. semicrystalline polyolefin) with from about 0.5 to about 3.5 mole percent of functional repeating units. Preferred functional groups are carboxylic acid groups and/or anhydride from a di or poly carboxylic acid. For the purposes of this application the polyolefin can be derived from polymerizing monoolefins or from polymerizing diolefins and then hydrogenating them to obtain similar microstructures to polyolefins. These polyolefins from diolefins can be block copolymers with other monomers such as stryene.
In some embodiments, the functionalized polyolefin and the polyolefin with the low flexural modulus and low crystallinity are the only required components of a hot-melt composition with excellent adhesion to polar polymers and textile fibers.
In another embodiment, a crosslinked rubber is present so that the rubbery properties of a thermoplastic vulcanizate are present.
In yet another thermoplastic vulcanizate embodiment, both a conventional high modulus polyolefin and rubber are present. The high modulus polyolefin can increase the stiffness and/or increase the softening temperature of the composition for uses requiring stiffness or having a higher use temperature requiring a higher softening temperature for the TPV.
Any of the above compositions can be used to adhere to polar polymers, metal, high tensile strength fibers and/or sheets. The excellent adhesion attributed to the combination of functionalized polyolefin and low crystallinity and low flexural modulus polyolefin is well utilized in melt processing a thermoplastic vulcanizate around a fiber or metal (e.g. wire) reinforced assembly.
Hydrosilylation crosslinking is a particularly advantageous type of crosslinking for the rubber phase as it has minimal side reactions with the functionalized polyolefin allowing the functionalized polyolefin to be blended with the other components before crosslinking the rubber phase.
The components of the invention vary depending on the requirements of the particular application. Two polymers are common to all applications. They are the low crystallinity, low flexural modulus polyolefin and the functionalized polyolefin. Other components that can be added are a rubber phase (usually crosslinked by dynamic vulcanization), an additional one or more semicrystalline polyolefins with higher flexural modulus, and conventional additives to a hot-melt adhesive or thermoplastic vulcanizate.
The first polyolefin can also be described as a polyolefin with low levels of crystallinity as compared to a highly isotactic semicrystalline polypropylene. Desirably the first polyolefin has from about 10, 12, 14, or 15 to about 20, 25, 26.5, 30, or 32 weight percent crystallinity. The weight percent crystallinity can be determined by dividing the heat of fusion of the sample as received by the heat of fusion of 100% crystalline polypropylene (assumed to be 209 joules/g). The first polyolefin, with low flexural modulus (tangent), can generally be any polyolefin with low polyolefin crystallinity and a flexural modulus desirably from about 5,000 to about 20,000 psi (34.5-138 MPa), more desirably from about 7,500 to about 17,500 psi (51.7-121 MPa) and preferably from about 9,000 to about 16,000 psi (62 to 110.4 MPa). The flexural modulus is measured by ASTM D 790A test method at 23xc2x0 C.
The first polyolefin can be a homopolymer with low crystallinity due to random or regular variations in tacticity, a copolymer that has low crystallinity due to the comonomer(s) and/or random or regular variations in tacticity (including blockly homo and copolymers), and polymers prepared by blending or grafting together oligomers or polymers. In particular, atactic and isotactic polypropylene (PP), in-situ blends, long isotactic PP sequence metallocene catalyzed ethylene-propylene copolymers (EP""s), elastic PPs with stereoblocks of atactic PP and isotactic PP (which can be metallocene catalyzed), isotactic PPs with metallocene catalyzed asymmetrical stereoerrors, isotactic PP and atactic PP combinations by blending or by stereoblocks from mixed metallocenes, and PPs that have an atactic PP backbone with isotactic PP branches using metallocene catalysis. For the purpose of this application, both the terms polymer and copolymer will be interpreted as including copolymers, terpolymers, etc., so that polymer includes copolymer and copolymer includes a polymer from three or more monomers. Desirably, at least 70, 80, or 90 weight percent of the repeat units are from olefin monomers having from 2 to 8 carbon atoms and preferably at least 70, 80, or 90 weight percent are derived from propylene monomer. Examples of operative low flexural modulus, low crystallinity polymers are Rexflex(copyright) 101 from Huntsman in Houston, Tex., characterized as a reactor blend of atactic and isotactic propylene homopolymer having about 10 to about 20 wt. % crystallinity and Adflex(copyright) KS 357P from Montell North America in Wilmington, Del., characterized as a polyolefin with low weight percent crystalline content of 10 to 20 wt. %.
When the first polyolefin with low crystallinity and low flexural modulus is used in a thermoplastic vulcanizate, it is desirably used in an amount from about 10 to about 400 parts by weight and more desirably from about 12.5 or 15 to about 350 or 400 parts by weight per 100 parts by weight of total rubber in the TPV. It is also desirable that the polyolefin with low crystallinity and low flexural modulus be present from about 10 to about 350 parts by weight and more desirably from about 15 to about 75 or 85 parts by weight per 100 total parts of semi-crystalline polyolefin in the thermoplastic phase. When the polyolefin with low crystallinity and low flexural modulus is used in a non-TPV application, then it is desirably present in an amount from about 20 to about 90 parts by weight and more desirably from about 25 to about 75 or 85 parts by weight per 100 parts by weight total polyolefins.
For the purpose of this application the total semicrystalline polyolefins includes the functionalized polyolefin if it has greater than 26.5 or 30 weight percent crystallinity.
In lieu of the polyolefin with low crystallinity and low flexural modulus one may be able to use a generally amorphous polyolefin (a polyolefin having less than 10 weight percent crystallinity and preferably less than 3 weight percent crystallinity) which will blend with a semicrystalline polyolefin such as isotactic polypropylene. This generally amorphous polyolefin is different than EPDM rubber in that it desirably has at least 75 mole percent and more desirably at least 80, 85, or 90 mole percent repeating units from a single olefin monomer, preferably propylene. This substitution is taught in WO 97/39059 as an alternative for the products marketed under the Rexene(trademark) and Rexflex(trademark) names. When the amorphous polyolefin is used in lieu of a low crystallinity polyolefin it should be used in an amount from about 5 to about 200 parts by weight, more desirably from about 6 or 7.5 to about 125 or 150 parts by weight per 100 parts total weight of rubber in the TPV. When the amorphous polyolefin is used in lieu of a low crystallinity polyolefin it should be used in an amount from about 5 to about 75 parts by weight, more desirably from about 7.5 to about 37 or 43 parts by weight per 100 parts total weight of semi-crystalline polyolefins in the thermoplastic phase. For the purpose of this application polyolefins with less than 10 weight percent crystallinity will be considered as amorphous.
The functionalized polyolefin desirably has from about 0.5 to about 3.5 mole percent functional groups, and more desirably from about 1 or 1.5 to about 2.0 or 2.5 mole percent functional groups based upon total repeating units in the polymer. The functional groups may be from monomers copolymerized with the olefin monomers or may be added by post-polymerization functionalization such as by grafting unsaturated monomers onto polyolefins as documented by U.S. Pat. No. 5,637,410 to BP Chemicals Limited which describes carboxylic acid grafting in columns 1 and 2. Desirably, at least 70, 80, or 90 weight percent of the repeating units for this polyolefin are olefin monomers of 2 to 8 carbon atoms and more preferably 2 or 3 carbon atoms. For the purposes of this application, functional groups will be defined as groups with heteroatoms other than carbon and hydrogen. Examples of functional groups include carboxylic acid groups, anhydrides from dicarboxylic or polycarboxylic acids, such as the group derived from grafting maleic anhydride to a polyolefin backbone. Preferred groups are carboxylic acid groups or anhydrides of two or more carboxylic acids. Thus the functionalized polyolefin can be a copolymer of acrylic acid and ethylene or propylene; a terpolymer of ethylene, vinyl acetate and acrylic acid; or a terpolymer of ethylene, methyl acrylate, acrylic acid; etc.
The polyolefin which is functionalized to make the functionalized polyolefin is desirably made from monoolefins so that it is compatible with the semicrystalline polyolefin phase. However there are other polymers having hydrogenated blocks made from from diolefins (e.g. conjugated dienes having from 4 to 8 carbon atoms) which polymer blocks are chemically indistinguishable from polyolefins polymerized from monoolefins by chemical analysis and have compatibility with the semicrystalline polymers made from monoolefins due to the similarities of their microstructure and their composition. For the purposes of this application these block copolymers with blocks of hydrogenated polydienes will be defined as polyolefins due to their equivalence to conventional polyolefins made from monoolefins. These polymers include homopolymers and block copolymers comprising blocks of polydiene that are subsequently hydrogenated. Blocks of hydrogenated polyisoprene look like perfectly random copolymers of ethylene and propylene. Blocks of hydrogenated polybutadiene look like copolymers of 1,2-butylene and ethylene. Commercially available hydrogenated blocky copolymers of dienes and styrene can function as the starting material for functionalized polyolefins due to the equivalence of the hydrogenated diene blocks to a polyolefin made from monoolefins. The polymer backbone of the functionalized material can also be a maleic anhydride modified hydrogenated styrene/butadiene/styrene (SBS) and/or hydrogenated styrene/butadiene/styrene (SEBS).
When the functionalized polyolefin is used in a thermoplastic vulcanizate (TPV) it is desirably used in an amount from about 10 or 15 to about 200 parts by weight, more desirably from about 15 or 20 to about 100 or 200 and preferably from about 40 to about 80 parts by weight per 100 parts by weight of rubbers in the TPV. It is also desirable that the functionalized polyolefin be present in an amount from about 10 to about 60 parts by weight and more desirably from about 12.5 to about 50 parts by weight per 100 total parts of polyolefin in the thermoplastic phase. When the functionalized polyolefin is used in a non-TPV application, it is desirably present in an amount from about 5 to about 60 parts by weight and more desirably from about 10 to about 50 parts by weight per 100 parts by weight total polyolefins.
A second semicrystalline polyolefin with higher flexural modulus can optionally be used in any of the embodiments. The higher flexural modulus is higher than the polyolefin with low crystallinity and low flexural modulus. This higher flexural modulus polymer desirably has a flexural modulus measured by ASTM D 790A of at least 30,000 psi (205 MPa) and more desirably at least 45,000 psi (310 MPa). The polymer can be made by any known polymerization process including low pressure and high pressure processes. The monomers are desirably olefins having from 2 to 8, 10, or 12 carbon atoms. Desirably, the second semicrystalline polyolefin has at least 70, 80, or 90 weight percent of repeat units from olefin monomers with the residual repeat units, if any, selected from copolymerizable monomers. The second semicrystalline polyolefin may be present to increase the amount of the polyolefin phase, which may be desirable to increase the processability of the composition or the hardness of the composition. The amount of a second semicrystalline polyolefin in a TPV, when present, is desirably in amounts up to 300 parts by weight and more desirably from about 5 to about 200, 250 or 300 parts by weight per 100 parts by weight of rubber. Desirably, in applications requiring the elastic properties of a TPV, the total polyolefins (polyolefin with low flexural modulus, functionalized polyolefin, and optional second polyolefin) are present in amount from about 20 to about 450 parts by weight per 100 parts by weight of rubber.
For the purposes of this application the semicrystalline polyolefins will include polyolefins with a at least 26.5 wt, % crystallinity. The functionalized polyolefin and any other semicrystalline polyolefins will be included in calculations for total semicrystalline polyolefins provided they have at least 26.5 wt. % crystallinity. It will not include rubbers such as EPDM rubber, which is a polyolefin but is generally defined as amorphous or essentially non-crystalline.
The rubber component can be any rubber suitable for use in a thermoplastic vulcanizate. These rubbers include ethylene-propylene-diene rubber (EPDM) (e.g. copolymer of two or more alphamonoolefins in weight ratios of 25:75 to 75:25 [if three or more monoolefins are used the then two have to be each be present in an amount of at least 25 weight percent of the total] with 0.2 to 10 wt % of repeating units from a polyene with 5 to 15 carbon atoms based on the weight of the EPDM); various isobutylene copolymers such as butyl rubber copolymers of isobutylene and p-methylstyrene, butyl rubber copolymers of isobutylene and a diene (including brominated and chlorinated versions), and copolymers or terpolymers of isobutylene and divinyl aromatic monomers; natural rubber; homopolymers of conjugated dienes having from 4 to 8 carbon atoms, optionally including halogens, such as polybutadiene, synthetic isoprene, and chloroprene rubber; or copolymers having at least 50 weight percent repeating units from said conjugated dienes, such as styrene-butadiene rubber and/or nitrile rubber: and combinations thereof.
While the description above is generally adequate for the rubbers in general in thermoplastic vulcanizates, in some embodiments using hydrosilylation crosslinking the preferred rubbers are as set forth below. Hydrosilylation crosslinking is taught in U.S. Pat. Nos. 4,803,244 and 5,672,660 hereby incorporated by reference. The preferred rubbers are those with residual carbon to carbon double bond unsaturation that is pendant to the polymer backbone and sterically unhindered with respect to reaction with the hydrosilylation crosslinking agent. Preferred rubbers with such sterically unhindered bonds react quickly with low concentrations of hydrosilylation crosslinking agent and low concentrations of catalyst.
Preferred rubbers for hydrosilylation crosslinking include rubbers from two or more xcex1-monoolefins, copolymerized with a polyene, usually a non-conjugated diene such as EPDM rubber, previously described. Useful polyenes include 5-ethylidene-2-norbornene (ENB); 1,4-hexadiene (HD); 5-methylene-2-norbornene (MNB); 1,6-octadiene; 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; 1,3-cyclopentadiene; 1,4-cyclohexadiene; dicyclopentadiene (DCPD); 5-vinyl-2-norbornene (VNB) and the like, or a combination thereof. 5-vinyl-2-norbornene (VNB) is a preferred polyene in EPBM for hydrosilylation crosslinking.
Another preferred rubber for hydrosilylation crosslinking is a copolymer or terpolymer of isobutylene and divinyl aromatic compounds. These polymers are described in U.S. Pat. Nos. 4,916,180 and 2,671,774, hereby incorporated by reference. These polymers desirably comprise from about 94 to about 99 or 99.5 weight percent repeating units from isobutylene, from about 0 or 0.5 to about 3 or 5 weight percent repeating units from a conjugated diene and from about 0.5 to about 3 or 5 weight percent repeating units from a divinyl aromatic monomer having the formula
wherein X is an aromatic (aryl) or an alkyl substituted aromatic moiety, and each R may be the same or different and is selected from hydrogen or a C1-5 alkyl. Divinyl benzene is a preferred example of the above divinyl aromatic monomer.
Another preferred rubber is a copolymer of isobutylene and para-methylstyrene which is post-polymerization functionalized with a halogen on the paramethyl group and then functionalized by replacing the halogen with an acrylic or alkacrylic group. This type of substitution chemistry on copolymers of isobutylene and para-methylstyrene is taught in U.S. Pat. No. 5,162,445 hereby incorporated by reference. This addition of the acrylic or alkacrylic group is well known to the art and involves the reaction of
where M+ is a metal ion such as Na+ or K+ and Br is bromine, an example of a halogen, the remainder of the isobutylene-paramethylstyrene is represented by the squiggly line, and each R group is independently H or an alkyl or alkylene of 1 to 4 carbon atoms. The product is
The curative or crosslinking system for the rubber can be any system conventionally used for thermoplastic vulcanizates. These include peroxide, azide, sulfur, phenolic resin and accelerated sulfur-vulcanizing agents. The combination of maleimide and disulfide accelerator can be used. Other curatives such as those used for butyl rubber include sulfur, phenolic resin, metal oxide, p-quinone dioxime, or bis-maleimide vulcanizing system. Halogenated butyl rubbers can be crosslinked with zinc oxide. The curatives or crosslinking systems are used in conventional amounts for crosslinking the rubber based upon the weight of the rubber component.
Alternatively, the crosslinking system can comprise a hydrosilylation crosslinking system such as described in U.S. Pat. Nos. 4,803,244 and 5,672,660, hereby incorporated by reference. Preferred silicon hydride compounds (hydrosilylation crosslinkers) include compounds of the formula
wherein each R is independently selected from the group consisting of alkyls comprising 1 to 20 carbon atoms, cycloalkyls comprising 4 to 12 carbon atoms and aryls. In formula (1) it is preferred that each R be independently selected from a group consisting of alkyls comprising 1 to 6 carbon atoms. Even more preferred is R=methyl, Rxe2x80x2 represents a hydrogen atom, an alkyl or alkoxy group having from 1 to about 24 carbon atoms. Rxe2x80x3 represents R or a hydrogen atom.
m is an integer having a value ranging from 1 to 50, n is an integer having a value ranging from 1 to 50, and p is an integer having a value ranging from 0 to 6.
Particularly preferred polyorganosiloxanes are those in which the silicon atom of the silicon hydride functionality is bound by heteroatoms/atoms having lone pairs of electrons. The preferred polyorganosiloxanes may also be substituted with appropriate functionality permitting solubility in the reaction media. A type of this functionalization is described in U.S. Pat. No. 4,046,930, which teaches alkylation of polyorganosiloxanes. The weight percent of alkylation should be limited to a level that permits adequate reaction rates and minimizes steric constraints.
The amount of silicon hydride compound useful in the process of the present invention can range from about 0.1 to about 10.0 mole equivalents of SiH per mole of carbon-carbon double bond in the rubber, and preferably is in the range of about 0.5 to about 5.0 mole equivalents of SiH per carbon-carbon double bond in the rubber component of the thermoplastic elastomer.
It has generally been understood that any hydrosilylation catalyst, or catalyst precursor capable of generating a catalyst in situ, which will catalyze the hydrosilylation reaction with the carbon-carbon bonds of the rubber, can be used. Such catalysts have included transition metals of Group VIII such as palladium, rhodium, platinum and the like, including complexes of these metals. Chloroplatinic acid has been disclosed as a useful catalyst in U.S. Pat. No. 4,803,244 and European Application No. 651,009, which further disclose that the catalyst may be used at concentrations of 5 to 10,000 parts per million parts by weight rubber and 100 to 200,000 parts per million parts by weight rubber, respectively.
Significantly lower concentrations of platinum-containing catalyst can be used, while obtaining improvement in both the speed of the reaction and the efficiency of the crosslinking. Concentrations of catalyst in the range of about 0.01 to about 20, 40 or 50 parts per million parts by weight of rubber, expressed as platinum metal, in combination with a diene-containing rubber having carbon-carbon multiple bonds which are predominately sterically unhindered, are effective in rapidly and completely curing the rubber in the process of dynamically vulcanizing blends of thermoplastic resin and rubber. Catalyst concentrations of about 0.1 to about 4 or 40 parts per million by weight expressed as platinum metal, and based on the weight of rubber, are particularly preferred.
Platinum-containing catalysts, which are useful in the process of the invention, are described, for example, in U.S. Pat. Nos. 4,578,497; 3,220,972; and 2,823,218, all of which are incorporated herein by this reference. These catalysts include chloroplatinic acid with symdivinyltetramethyldisiloxane, dichloro-bis (triphenylphosphine) platinum (II), cis-dichloro-bis (acetonitrile) platinum (II), dicarbonyldichloroplatinum (II), platinum chloride and platinum oxide. Zero valent platinum metal complexes such as Karstedt""s catalyst are particularly preferred.
In order for the catalyst to function most efficiently in the dynamic vulcanization environment, it is important that it is inherently thermally stable, or that its activity is inhibited to prevent too rapid a reaction or catalyst decomposition. Appropriate catalyst inhibitors that are suitable to stabilize the platinum catalyst at high temperature include 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane and its higher analogs such as vinyl cyclic pentamer. However, other olefins that are stable above 165xc2x0 C. are also useful. These include maleates, fumarates and the cyclic pentamer. It is also particularly preferred in the invention to use a catalyst that remains soluble in the reaction medium.
The thermoplastic elastomer may contain conventional additives, which can be introduced into the composition in the thermoplastic resin, the rubber, or in the blend before, during or after curing. Examples of such additives are antioxidants, processing aids, reinforcing and non-reinforcing fillers, pigments, waxes, rubber processing oil, extender oils, antiblocking agents, antistatic agents, ultraviolet stabilizers, plasticizers (including esters), foaming agents, flame retardants and other processing aids known to the rubber compounding art. Such additives may comprise from about 1 to about 300 percent by weight based on the weight of the total polyolefins and rubber in the final thermoplastic elastomer product. Fillers and extenders, which can be utilized, include conventional inorganics such as calcium carbonate, clays, silica, talc, titanium dioxide, carbon black and the like. The rubber processing oils generally are paraffinic, naphthenic or aromatic oils derived from petroleum fractions. The type will be that ordinarily used in conjunction with the specific rubber or rubbers present in the composition, and the quantity of processing oil based on the total rubber content of the thermoplastic elastomer may range from zero or 50 to several hundred parts by weight per hundred parts by weight of rubber. Important to the efficiency of the catalyst is that the oils and other additives contain no or very low concentrations of compounds that interfere with the activity of the catalyst. These include phosphines, amines, sulfides or other compounds that may be classified as Lewis bases.
The rubber component of the thermoplastic elastomer is generally present as small, i.e. micron-size particles within a continuous thermoplastic resin matrix, although a co-continuous morphology or a phase inversion is also possible depending upon the amount of rubber relative to plastic and the degree of cure of the rubber. The rubber is desirably at least partially crosslinked, and preferably is completely or fully crosslinked. It is preferred that the rubber be crosslinked by the process of dynamic vulcanization. As used in the specification and claims, the term xe2x80x9cdynamic vulcanizationxe2x80x9d means a vulcanization or curing process for a rubber blended with a thermoplastic resin, wherein the rubber is vulcanized under conditions of shear at a temperature at which the mixture will flow. The rubber is thus simultaneously crosslinked and dispersed as fine particles within the thermoplastic resin matrix, although as noted above other morphologies may exist. Dynamic vulcanization is effected by mixing the thermoplastic elastomer components at elevated temperatures in conventional mixing equipment such as multiple-roll roll mills, Banbury mixers, Brabender mixers, continuous mixers, mixing extruders and the like. Generally after a reasonably homogenous mixture of the two phases is established, the curatives are added. Mixing is continued until maximum mixing torque is reached. Thereafter mixing is continued one or two minutes. The unique characteristics of dynamically cured compositions is that, notwithstanding the fact that the rubber component is partially or fully cured, the compositions can be processed and reprocessed by conventional plastic processing techniques such as extrusion, injection molding and compression molding. Scrap or flashing can be salvaged and reprocessed.
It is preferred to prepare a dynamic vulcanizate as described above when using peroxide, sulfur, and the phenolic curatives. Peroxide curatives may cause some chain scission of polyolefins. The functionalized polyolefin is generally, but not necessarily, added after curing the rubber phase, to avoid any chemical interaction between the curative and the functional groups of the functionalized polyolefin. The addition of the functionalized polyolefin can occur in the same equipment or separate equipment from the preparation of the thermoplastic vulcanizate. The polyolefin with the low crystallinity and low flexural modulus can be added in any stage of the processing, e.g. before or after curing the rubber phase. Commercial thermoplastic vulcanizates can be converted to thermoplastic vulcanizates with excellent adhesion to textile fibers, by adding during melt blending appropriate amounts of functionalized polyolefin and polyolefin with low crystallinity and low flexural modulus.
As the hydrosilylation crosslinking system does not appreciably react with maleic anhydride functionalized polyolefin, the functionalized polyolefin can be added before the crosslinking (curing) step eliminating the extra addition step after crosslinking.
The polar polymer can be any polymer more polar than polyolefins. The polar polymer can be a molded or shaped article onto which a thermoplastic coating is applied or it may be in the form of sheets or fibers. Desirably the polar polymer and the fiber or sheet reinforcement may be any high tensile modulus material (e.g. above 130,000 psi, more desirably above 180,000 psi) that can desirably be formed into fibers or sheets. Examples include polyesters, polyamides, glass fibers, natural fibers such as cellulosic, etc. The fibers can be woven, bundled, yarns, non-woven, etc. In addition polyolefin polymers may be used to make the fibers or blends of polyolefins and the polar polymers may form the fibers, or blends of polyolefin fibers and polar polymer fibers may be used.
The hot melt adhesive or the thermoplastic vulcanizate of this disclosure also adheres well to metallic substrates. Thus they may be used as a coating on metallic parts, sheets, or fibers (wires) or used to form molded or shaped parts that include metal such as sheets or wires as part of or adhered to a molded or shaped article. Examples of products formed with these thermoplastic vulcanizates include covers for hydraulic hoses, tube and cover for fire fighting hoses, belting, roofing, etc.

TPE composition that exhibits excellent adhesion to textile fibers


An infant carrier configured to be worn by a wearer is disclosed. The infant carrier includes a seat support configured to support an infant""s bottom, a back support, which is integral with the seat support, a head support which is integral with the back support and a strap support system which is worn around the wearer""s torso to support the infant in the infant carrier. The seat support is diaper-like in shape with a front notch to prevent chafing the infant. Preferably, the strap support system is made up of a single pair of straps. Preferably, there is a separation (e.g., a seam) between the back support and the head support which allows the head support to be folded down when not being used to support the infant""s head.

(Not Applicable)
(Not Applicable)
The present invention relates generally to carrying devices for infants and small children, and more particularly to an improved, infant carrier which is more comfortable for the infant and the wearer.
It is common practice for a parent to employ the use of a baby carrier for carrying an infant. Indeed, various types of baby carriers are currently available from manufacturers of infant products. Though such currently known and available baby carriers achieve their primary objective of carrying an infant, they possess certain deficiencies which detract from their overall utility.
Of primary concern is support and safety of the infant. One of the key concerns with regard to support of the infant is support of the infant""s head. A young infant""s head tends to flop around and therefore requires support. As the child gets older, he/she can hold up his/her own head. Due to the fluctuating need for head support, a head support may be desired only some of the time. Thus, infant carriers with removable head rests (for example, see U.S. Pat. No. 5,246,152, issued to Dotseth) have been developed. While an improvement over the prior art, infant carriers with removable head rests are limited in that if the headrest is removed, it must be carried separately or left at another location where it is not readily accessible. Thus, a need exists for an infant carrier with a xe2x80x9cconvertiblexe2x80x9d headrest or head support such that the headrest can be used if desired, but can also not be used without actually having to remove it.
Another area of typical discomfort for infants being carried in an infant carrier is chafing of the infant in the neck area (e.g., under the chin). Typical infant carriers include a seat support portion which holds the child""s bottom. This seat support area typically looks like a diaper, in that it is triangular in shape and includes leg openings for the infant""s legs to protrude from. Like a diaper, the seat support of infant carriers tend to have a top portion that extends linearly across the child""s chest. However, unlike a diaper, the infant carrier must be constructed of a more durable, less flexible fabric than a diaper in order to provide support. Thus, since infants and small children have a tendency to lean forward (towards the wearer) when in a typical infant carrier device, there is a tendency for the area of the infant""s neck under its chin to be firmly engaged against the top portion of the seat support of such carrier, often resulting in the chaffing of the infant""s neck and, in extreme cases, difficulty in breathing. Thus, a need exists for an infant carrier which will not interfere with the neck of an infant or small child that is leaning forward and/or has its head sagging downwardly in a forward facing position.
Another area of concern is the comfort and ease of use (e.g., putting on, adjusting and removing the carrier) for the wearer (e.g., parent). Typical infant carriers include many straps and buckles which are often difficult for a wearer to put on and/or take off. These devices are not always easy to adjust. Furthermore, it is often difficult for wearers to adjust such infant carriers so that they are comfortable for the wearer. Thus, a need exists for a strap system which provides for secure carrying of the infant, yet is easy for the wearer to put on, take off and adjust. Furthermore, the strap system should be comfortable for the wearer.
The present invention addresses the above described deficiencies in the prior art by providing an infant carrier which is safe and provides proper support for the infant, yet is more comfortable for the child. Additionally, the infant carrier is comfortable for the wearer and easily adjustable.
In accordance with the present invention, there is provided an infant carrier which is configured to be worn by a wearer. The infant carrier comprises a seat support which is configured to support the infant""s bottom. The seat support includes two openings for the infant""s legs and defines a front having a notch formed therein which is sized and configured to provide clearance for the infant""s head when the infant is in the infant carrier. The notch preferably has a generally V-shaped configuration defining first and second sides which meet at a point. In addition to the seat support, the infant carrier includes a back support which is integral with the seat support and configured to support the infant""s back. Also included in the infant carrier is a head support which is integral with the back support and configured to support the infant""s head. Attached to the seat support is a strap support system which is adapted to be worn around the wearer""s torso.
In the present infant carrier, a transition region or seam is defined between the back and head supports. The transition region is sized and configured to allow the head support to be selectively moved between an unfolded position and a folded position. When the head support is moved into the folded position, it is folded down into an overlapping relation to the back support, thus exposing the head, shoulders and upper portion of the torso of the infant. The head support preferably includes a pouch which is selectively movable between an open position and a closed position. Disposed within the pouch is a deployable hood which is attached to the head support, as well as a deployable shroud which is also attached to the head support. The hood, when deployed, is positionable over the infant""s head within the infant carrier. The shroud, when deployed, is itself placable over the entirety of the infant carrier having the infant positioned therewithin.
In the present infant carrier, the strap system comprises an elongate first strap having a first end portion which is attached to the seat support adjacent the first side of the notch. Disposed on the first strap is a first connector piece which is normally located in close proximity to the second, free end of the first strap. The strap support system also includes an elongate second strap having a first end portion which is itself attached to the seat support adjacent the second side of the notch. Disposed on the second strap is a second connector piece which is normally disposed in relative close proximity to the second, free end of the second strap. Attached to the seat support adjacent the second side of the notch is a first mating connector, while also attached to the seat support adjacent the first side of the notch is a second mating connector. The first and second straps are extensible over the wearer""s shoulders in a manner wherein the first and second straps criss-cross each other over the wearer""s back such that the first connector piece may be interlocked to the first mating connector and the second connector piece may be interlocked to the second mating connector.
The infant carrier of the present invention further comprises a first row of snap bases which are attached to the first strap and a second row of snap bases which are attached to the second strap. Also attached to the first strap is a first strip of material having a first row of snap connectors attached thereto. The first strip of material is attached to the first strap such that the snap connectors of the first row are selectively engagable to respective ones of the snap bases of the first row. Attached to the second strap is a second strip of material which has a second row of snap connectors attached thereto. The second strip of material is attached to the second strap such that the snap connectors of the second row are selectively engagable to respective ones of the snap bases of the first row.
In the infant carrier of the present invention, a pair of swivel connectors are preferably used to attach respective ones of the first and second straps to the head support. The swivel connectors are adapted to assist in the movement of the head support between its unfolded and folded positions. The first swivel connector includes a first connector ring which may be selectively captured between any adjacent pair of engaged snap connectors and snap bases of the first rows. Similarly, the second swivel connector includes a second connector ring which may be selectively captured between any adjacent pair of engaged snap connectors and snap bases of the second rows.


A system for protocol processing in a computer network has an intelligent network interface card (INIC) or communication processing device (CPD) associated with a host computer. The INIC provides a fast-path that avoids protocol processing for most large multi-packet messages, greatly accelerating data communication. The INIC also assists the host for those message packets that are chosen for processing by host software layers. A communication control block for a message is defined that allows DMA controllers of the INIC to move data, free of headers, directly to or from a destination or source in the host. The context is stored in the INIC as a communication control block (CCB) that can be passed back to the host for message processing by the host. The INIC contains specialized hardware circuits that are much faster at their specific tasks than a general purpose CPU. A preferred embodiment includes a trio of pipelined processors with separate processors devoted to transmit, receive and management processing, with full duplex communication for four fast Ethernet nodes.

The present invention relates generally to computer or other networks, and more particularly to protocol processing for information communicated between hosts such as computers connected to a network.
The advantages of network computing are increasingly evident. The convenience and efficiency of providing information, communication or computational power to individuals at their personal computer or other end user devices has led to rapid growth of such network computing, including internet as well as intranet systems and applications.
As is well known, most network computer communication is accomplished with the aid of a layered software architecture for moving information between host computers connected to the network. The layers help to segregate information into manageable segments, the general functions of each layer often based on an international standard called Open Systems Interconnection (OSI). OSI sets forth seven processing layers through which information may pass when received by a host in order to be presentable to an end user. Similarly, transmission of information from a host to the network may pass through those seven processing layers in reverse order. Each step of processing and service by a layer may include copying the processed information. Another reference model that is widely implemented, called TCP/IP (TCP stands for transport control protocol, while IP denotes internet protocol) essentially employs five of the seven layers of OSI.
Networks may include, for instance, a high-speed bus such as an Ethernet connection or an internet connection between disparate local area networks (LANs), each of which includes multiple hosts, or any of a variety of other known means for data transfer between hosts. According to the OSI standard, physical layers are connected to the network at respective hosts, the physical layers providing transmission and receipt of raw data bits via the network. A data link layer is serviced by the physical layer of each host, the data link layers providing frame division and error correction to the data received from the physical layers, as well as processing acknowledgment frames sent by the receiving host. A network layer of each host is serviced by respective data link layers, the network layers primarily controlling size and coordination of subnets of packets of data.
A transport layer is serviced by each network layer and a session layer is serviced by each transport layer within each host. Transport layers accept data from their respective session layers and split the data into smaller units for transmission to the other host""s transport layer, which concatenates the data for presentation to respective presentation layers. Session layers allow for enhanced communication control between the hosts. Presentation layers are serviced by their respective session layers, the presentation layers translating between data semantics and syntax which may be peculiar to each host and standardized structures of data representation. Compression and/or encryption of data may also be accomplished at the presentation level. Application layers are serviced by respective presentation layers, the application layers translating between programs particular to individual hosts and standardized programs for presentation to either an application or an end user. The TCP/IP standard includes the lower four layers and application layers, but integrates the functions of session layers and presentation layers into adjacent layers. Generally speaking, application, presentation and session layers are defined as upper layers, while transport, network and data link layers are defined as lower layers.
The rules and conventions for each layer are called the protocol of that layer, and since the protocols and general functions of each layer are roughly equivalent in various hosts, it is useful to think of communication occurring directly between identical layers of different hosts, even though these peer layers do not directly communicate without information transferring sequentially through each layer below. Each lower layer performs a service for the layer immediately above it to help with processing the communicated information. Each layer saves the information for processing and service to the next layer. Due to the multiplicity of hardware and software architectures, systems and programs commonly employed, each layer is necessary to insure that the data can make it to the intended destination in the appropriate form, regardless of variations in hardware and software that may intervene.
In preparing data for transmission from a first to a second host, some control data is added at each layer of the first host regarding the protocol of that layer, the control data being indistinguishable from the original (payload) data for all lower layers of that host. Thus an application layer attaches an application header to the payload data and sends the combined data to the presentation layer of the sending host, which receives the combined data, operates on it and adds a presentation header to the data, resulting in another combined data packet. The data resulting from combination of payload data, application header and presentation header is then passed to the session layer, which performs required operations including attaching a session header to the data and presenting the resulting combination of data to the transport layer. This process continues as the information moves to lower layers, with a transport header, network header and data link header and trailer attached to the data at each of those layers, with each step typically including data moving and copying, before sending the data as bit packets over the network to the second host.
The receiving host generally performs the converse of the above-described process, beginning with receiving the bits from the network, as headers are removed and data processed in order from the lowest (physical) layer to the highest (application) layer before transmission to a destination of the receiving host. Each layer of the receiving host recognizes and manipulates only the headers associated with that layer, since to that layer the higher layer control data is included with and indistinguishable from the payload data. Multiple interrupts, valuable central processing unit (CPU) processing time and repeated data copies may also be necessary for the receiving host to place the data in an appropriate form at its intended destination.
The above description of layered protocol processing is simplified, as college-level textbooks devoted primarily to this subject are available, such as Computer Networks, Third Edition (1996) by Andrew S. Tanenbaum, which is incorporated herein by reference. As defined in that book, a computer network is an interconnected collection of autonomous computers, such as internet and intranet systems, including local area networks (LANs), wide area networks (WANs), asynchronous transfer mode (ATM), ring or token ring, wired, wireless, satellite or other means for providing communication capability between separate processors. A computer is defined herein to include a device having both logic and memory functions for processing data, while computers or hosts connected to a network are said to be heterogeneous if they function according to different operating systems or communicate via different architectures.
As networks grow increasingly popular and the information communicated thereby becomes increasingly complex and copious, the need for such protocol processing has increased. It is estimated that a large fraction of the processing power of a host CPU may be devoted to controlling protocol processes, diminishing the ability of that CPU to perform other tasks. Network interface cards have been developed to help with the lowest layers, such as the physical and data link layers. It is also possible to increase protocol processing speed by simply adding more processing power or CPUs according to conventional arrangements. This solution, however, is both awkward and expensive. But the complexities presented by various networks, protocols, architectures, operating systems and applications generally require extensive processing to afford communication capability between various network hosts.
The current invention provides a system for processing network communication that greatly increases the speed of that processing and the efficiency of moving the data being communicated. The invention has been achieved by questioning the long-standing practice of performing multilayered protocol processing on a general-purpose processor. The protocol processing method and architecture that results effectively collapses the layers of a connection-based, layered architecture such as TCP/IP into a single wider layer which is able to send network data more directly to and from a desired location or buffer on a host. This accelerated processing is provided to a host for both transmitting and receiving data, and so improves performance whether one or both hosts involved in an exchange of information have such a feature.
The accelerated processing includes employing representative control instructions for a given message that allow data from the message to be processed via a fast-path which accesses message data directly at its source or delivers it directly to its intended destination. This fast-path bypasses conventional protocol processing of headers that accompany the data. The fast-path employs a specialized microprocessor designed for processing network communication, avoiding the delays and pitfalls of conventional software layer processing, such as repeated copying and interrupts to the CPU. In effect, the fast-path replaces the states that are traditionally found in several layers of a conventional network stack with a single state machine encompassing all those layers, in contrast to conventional rules that require rigorous differentiation and separation of protocol layers. The host retains a sequential protocol processing stack which can be employed for setting up a fast-path connection or processing message exceptions. The specialized microprocessor and the host intelligently choose whether a given message or portion of a message is processed by the microprocessor or the host stack.

Passing a communication control block to a local device such that a message is processed on the device


Disclosed are methods and compositions capable of rapidly preparing mammalian tissue and organs for harvesting and subsequent transplantation while minimizing the potential for infection of the harvested tissues and organs. This invention is also directed to methods and compositions used to prepare the donor for subsequent handling by a mortician.

1. Field of the Invention
This invention is directed to methods and compositions capable of rapidly preparing mammalian tissue and organs for harvesting and subsequent transplantation while minimizing the potential for infection of the harvested tissues and organs. This invention is also directed to methods and compositions used to prepare the donor for subsequent handling by a mortician.
2. References
The following publications, patent applications and patents are cited in this application as superscript numbers:
1 Barley, xe2x80x9cMethods for Retarding Blister Formation by Use of Cyanoacrylate Adhesivesxe2x80x9d, U.S. Pat. No. 5,306,490, issued Apr. 26, 1994.
2 Barley, et al., Methods for Treating Suturable Wounds by Use of Sutures and Cyanoacrylate Adhesives, U.S. Pat. No. 5,254,132, issued Oct. 19, 1993
3 McIntire, et al., Process for the Preparation of Poly (xcex1-Cyanoacrylates), U.S. Pat. No. 3,654,239, issued Apr. 4, 1972
4 Barley, et al., International Patent Application Publication No. WO 93/25196, for Methods for Treating Non-Suturable Wounds by Use of Cyanoacrylate Adhesives, published Dec. 23, 1993
5 Barley, et al., Methods for Reducing Skin Irritation From Artificial Devices by Use of Cyanoacrylate Adhesives, U.S. Pat. No. 5,653,769, issued Aug. 5, 1997
6 Tighe, et al., Methods for Inhibiting Skin Ulceration by Use of Cyanoacrylate Adhesives, U.S. Pat. No. 5,403,591, issued Apr. 4, 1995
7 Tighe, et al., for Use of Cyanoacrylates for Providing a Protective Barrier Film for the Skin, U.S. Pat. No. 5,580,565, issued Dec. 6, 1996
8 Askill, et al., for Methods for Draping Surgical Incision Sites, U.S. Pat. No. 5,807,563 issued Sep. 15, 1998
All of the above publications, patent applications and patents are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent application or patent was specifically and individually indicated to be incorporated by reference in its entirety.
The procedures for harvesting tissues and organs for transplantation, implantation, research and other medical uses are fraught with complications which can cause reluctance to approve the use of the deceased in a donor program and limit the utility of the recovered tissues. Among these complications are infection of the removed tissues as well as ensuring that the donor""s body is cosmetically acceptable after removal of the desired tissues and/or organs.
The infection rate for harvested tissues is approximately 30% despite extensive anti-infective procedures during organ and/or tissue harvest. After treatment of the harvested tissues and organs, there are approximately 10% that remain unusable due to infection.
Current practice in human cadavers is to first prepare the skin for subsequent tissue and/or organ harvesting by use of alcohol washes, followed by iodophor scrubs such as Betadine, followed by draping the incision site with a surgical incise drape such as Ioban. Such procedures are time consuming and expensive and all of the preparations have to be removed and all incisions have to be repaired to make the donor cosmetically presentable to family and friends.
Sutures and staples are frequently used for incision closures in human cadavers, but without the hemostasis mechanisms present in living tissue, mechanical closure will not prevent egress of body fluids. Commercial superglues, such as ethyl cyanoacrylate, are sometimes used to seal these incisions but the resulting polymer is too brittle and can easily crack whereas the reactive monomer can react too quickly making it hard to control. These superglues also have an unpleasant sharp odor and are respiratory irritants.
This invention is directed, in part, to the discovery that the in situ formation of a cyanoacrylate polymeric film at the site of tissue and/or organ harvesting overcomes many of the prior art problems noted above. For example, the cyanoacrylate polymer is known in the art to have bacteriostatic properties and the cyanoacrylate monomer permits the inclusion of compatible antimicrobial agents if such is desired. Still another advantage is the formation of an appropriately configured film which completely covers the transplantation area and forms a waterproof film over the skin, thereby inhibiting infection. Subsequent to tissue and/or organ harvesting, the reformation of the polymeric film over the incision site prevents fluid loss as well as improves the cosmetic appearance of the donor. Finally, the use of suitable cyanoacrylates with or without an appropriate perfume overcomes prior art problems with unpleasant odors and respiratory irritants.
The use of cyanoacrylate polymers per this invention is in contrast to their known medical uses as an alternative or adjunct to sutures2 or as a hemostat3. Other described uses of cyanoacrylate prepolymers include their use on mammalian tissue to form polymeric films which are utilized:
to prevent friction blister formation1,
in treating small non-suturable wounds4,
in inhibiting surface skin irritation arising from friction between the skin surface and artificial devices such as tapes, prosthetic devices, casts, etc.5,
as surgical incise drapes8,
in inhibiting skin ulcerations6, and
forming a protective film to inhibit skin degradation due to incontinence.7
This invention is directed to methods for the rapid and effective preparation of donor skin for tissue and/or organ transplation by the in situ formation of a cyanoacrylate film from a cyanoacrylate prepolymer. A film-forming cyanoacrylate prepolymer can also be used to seal incisions and tissue/organ harvest sites so as to restore mechanical integrity and prevent fluid leakage from these sites. Preferably, the cyanoacrylate prepolymer compositions contain an antimicrobial agent or a plurality of agents to further inhibit infection in the harvested tissue and/or organs.
Such methods involve application of a cyanoacrylate prepolymer composition onto the cadaver skin at the site of tissue and/or organ transplantation followed by in situ polymerization of the prepolymer to form a polymeric film. The cyanoacrylate prepolymer composition can be applied as a liquid/gel to the skin surface and can include antimicrobial agents, and the like. Subsequent to formation of the cyanoacrylate film, an incision is made there through and the appropriate tissues/organs are harvested. In a particularly preferred embodiment, a cyanoacrylate prepolymer is then used to seal incisions and tissue/organ harvest sites so as to restore mechanical integrity to the cadaver and/or to prevent fluid leakage from these sites.
Accordingly, in one of its method aspects, this invention is directed to a method for harvesting tissue and/or organs from a mammalian cadaver which method comprises:
(a) identifying the tissue and/or organ to be harvested from a mammalian cadaver;
(b) applying a sufficient amount of a composition comprising a polymerizable cyanoacrylate ester to the skin covering the tissue and/or organ defined in (a) above so as to cover this skin with the composition;
(c) polymerizing the cyanoacrylate ester so as to form a flexible, waterproof, adhesive polymer film which adheres to and overlays the skin area(s) where the composition was applied; and
(d) harvesting said tissue and/or organ by incision through the polymeric film and the underlying skin and subsequent removal of the tissue and/or organ.
Preferably, the polymerizable cyanoacrylate ester comprises an ester which, in monomeric form, is represented by formula I:
where R is selected from the group consisting of:
alkyl of 3 to 10 carbon atoms,
alkenyl of 2 to 10 carbon atoms,
cycloalkyl groups of from 5 to 8 carbon atoms,
phenyl,
2-ethoxyethyl,
3-methoxybutyl,
3-propoxypropyl,
and a substituent of the formula:
wherein each Rxe2x80x2 is independently selected from the group consisting of:
hydrogen and methyl, and
Rxe2x80x3 is selected from the group consisting of:
alkyl of from 1 to 6 carbon atoms,
alkenyl of from 2 to 6 carbon atoms,
alkynyl of from 2 to 6 carbon atoms,
cycloalkyl of from 3 to 8 carbon atoms,
aralkyl selected from the group consisting of benzyl, methylbenzyl and phenylethyl,
phenyl, and
phenyl substituted with 1 to 3 substituents selected from the group consisting of hydroxy, chloro, bromo, nitro, alkyl of 1 to 4 carbon atoms, and alkoxy of from 1 to 4 carbon atoms.
More preferably, in the cyanoacrylate esters of formula I, R is alkyl of from 2 to 10 carbon atoms and more preferably alkyl of from 2 to 8 carbon atoms. Even more preferably, R is butyl, pentyl or octyl and most preferably, R is n-butyl.
In another preferred embodiment, the polymerized cyanoacrylate composition has a thickness of no more than about 1 millimeter and, more preferably, the polymer layer has a thickness of from about 2 to about 500 microns and still more preferably from about 20 to about 100 microns.
Preferably, the mammalian cadaver is a human cadaver.
More preferably, subsequent to harvesting of the tissue and/or organ, the incision site and/or tissue/organ harvest sites are sealed by application of a cyanoacrylate prepolymer so as to restore mechanical integrity to the cadaver and/or to prevent fluid leakage from these sites.
This invention is directed to methods of rapidly preparing mammalian tissue and organs for harvesting and subsequent transplantation while minimizing the potential for infection of the harvested tissues and organs.
As used herein, the following terms have the following meanings:
The term xe2x80x9cmammalian cadaverxe2x80x9d refers to the bodily remains of a mammalian subject for which tissue and/or organs will be harvested. Preferably, the mammalian cadaver is a human cadaver.
The term xe2x80x9cpolymerizable cyanoacrylate estersxe2x80x9d refers to polymerizable formulations comprising cyanoacrylate monomers or polymerizable oligomers which, in their monomeric form, are preferably compounds represented by formula I as described above.
More preferably, in formula I, R is an alkyl group of from 3 to 10 carbon atoms including ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, n-pentyl, iso-pentyl, n-hexyl, iso-hexyl, 2-ethylhexyl, n-heptyl, octyl, nonyl, and decyl or R is an alkoxyalkyl of from 4 to 10 carbon atoms such as ethoxyethyl or propoxypropyl. More preferably, R is butyl, pentyl or octyl and most preferably, R is n-butyl. Mixtures of such compounds can also be employed as disclosed by Berger, et al., U.S. Pat. No. 5,998,472 which is incorporated herein by reference in its entirety.
A preferred cyanoacrylate ester for use in the invention is 2-ethoxyethyl cyanoacrylate.
Such polymerizable cyanoacrylate esters are sometimes referred to herein as prepolymers and compositions comprising such esters are sometimes referred to herein as prepolymer compositions.
Polymerizable cyanoacrylate esters are known in the art and are described in, for example, U.S. Pat. Nos. 3,527,224; 3,591,676; 3,667,472; 3,995,641; 4,035,334; and 4,650,826 the disclosures of each are incorporated herein by reference in their entirety.
The term xe2x80x9cbiocompatible plasticizerxe2x80x9d refers to any material which is soluble or dispersible in the cyanoacrylate composition, which increases the flexibility of the resulting polymeric film coating on the skin surface, and which, in the amounts employed, is compatible with the skin as measured by the lack of moderate to severe skin irritation. Suitable plasticizers are well known in the art and include those disclosed in U.S. Pat. Nos. 2,784,127 and 4,444,933 the disclosures of both of which are incorporated herein by reference in their entirety. Specific plasticizers include, by way of example only, acetyl tri-n-butyl citrate (preferably xcx9c20 weight percent or less), acetyl trihexyl citrate (preferably xcx9c20 weight percent or less) butyl benzyl phthalate, dibutyl phthalate, dioctylphthalate, n-butyryl tri-n-hexyl citrate, diethylene glycol dibenzoate (preferably xcx9c20 weight percent or less) and the like. The particular biocompatible plasticizer employed is not critical and preferred plasticizers include dioctylphthalate and C2-C4-acyl tri-n-hexyl citrates.
The term xe2x80x9cantimicrobial agentxe2x80x9d refers to agents which destroy microbes (i.e., bacteria, fungi, yeasts and viruses) thereby preventing their development and their pathogenic action.
Suitable antimicrobial agents for use in this invention include, for example, poloxamer iodophors, hexyl resourcinol, salicyclic acid, 2-phenyl-ethanol, 4-chloro-3,5-dimethylphenol, benzoic acid, sorbic acid and the like.
The methods of this invention comprise the in situ formation of a cyanoacrylate polymer film on the skin surface at the site of incision of the mammalian cadaver where tissue and/or organ harvesting is to occur which polymeric film acts as a barrier film in inhibiting the introduction of or migration of pathogens into the incision site.
The treatment protocol preferably involves skin preparation prior to in situ formation of the cyanoacrylate polymer film at the incision site. Specifically, this site is conventionally pretreated by cleaning with an appropriate antimicrobial composition. The site is then preferably dried, e.g., blotted dry, and then an adherent polymeric film is formed over this site by application of a polymerizable cyanoacrylate composition. As noted above, this composition comprises polymerizable cyanoacrylate monomers and/or reactive oligomers which, upon contact with the skin site polymerizes in situ to form a polymeric film.
Polymerization occurs at ambient conditions for a sufficient period of time to allow polymerization to proceed. In general, the particular length of time required for polymerization will vary depending on factors such as the amount of adhesive composition applied, the temperature of the site, the moisture content of the site, the extent surface area of the site, and the like. However, in a preferred embodiment, polymerization is generally complete within about 10 to about 60 seconds while the site is maintained at or below ambient conditions (e.g., from about 0xc2x0 C. to about 20xc2x0 C.); however, in some cases, polymerization can occur up to about 5 minutes. During this period, the cadaver is maintained in a position which permits the cyanoacrylate to polymerize and form a polymeric film while minimizing any movement which might dislodge the cyanoacrylate from that site or create undesirable bonding.
Sufficient amounts of the composition are employed to cover (i.e., coat) the entire site with a layer of the cyanoacrylate polymer. If necessary, excess cyanoacrylate monomer and/or oligomer can be removed with a wipe or tissue paper before polymerization or, after polymerization, any polymer formed at unintended sites can be removed with materials such as acetone.
After polymerization, the resulting polymeric film forms a barrier film which strongly adheres to the skin, is flexible and waterproof. Such strong adherence effectively eliminates the possibility that the film will separate from the cadaver which would otherwise permit the undesirable introduction of microbes and/or permit leakage from the harvested site.
The polymeric film should be maintained in an unbroken manner over the entire site. This can be assured by careful application of the cyanoacrylate adhesive onto the site. Additionally, the use of a plasticizer will facilitate the maintenance of the polymeric film in an unbroken manner and will inhibit cracking of the film.
In one embodiment, after application of the initial polymeric layer, a second, preferably thinner, layer is applied thereto. Additional amounts of cyanoacrylate adhesive composition can be applied as needed to maintain an unbroken coating covering the site.
Application is conducted under conditions wherein the polymeric film preferably has a thickness of no more than about 1 millimeter and, more preferably, the polymer layer has a thickness of from about 2 to about 500 microns and still more preferably from about 20 to about 100 microns. If thinner polymeric films are desired, then the polymeric film should have a thickness of from about 2 to about 50 microns and preferably from 10 to 40 microns. The amount of cyanoacrylate composition applied to a unit area to obtain such thicknesses is well within the skill of the art.
The size and thickness of the polymeric film formed onto the site can be readily controlled by the amount and viscosity of cyanoacrylate adhesive composition packaged in a single dose product or by use of a multiple use dispenser which governs the amount of material applied onto a unit area of surface skin. In this regard, the dispenser described by Otake, U.S. Pat. No. 4,958,748, which is incorporated by reference in its entirety, is one example of a dispenser which dispenses the cyanoacrylate adhesive composition in a controlled dropwise manner. Other methods for the controlled dispersement of the cyanoacrylate adhesive include, by way of example, a spray applicator, brush, wipe, swab or solid paddle applicator, applicators for repeated and intermittent use of the cyanoacrylate composition and the like.
In applicators, the cyanoacrylate composition is stored at ambient conditions and can be provided in sterile form.
In a preferred embodiment, the prepolymeric cyanoacrylate composition is presented in a telescopic applicator with a foil-sealed rear compartment containing, e.g., 6 grams, of this composition. The compartment is made from polypropylene and is heat-sealed at the end with a laminated aluminum/polyethylene foil. The remainder of the housing is made from high-density polyethylene, has a piercing device close to the front, and has a heat-bonded, small-pore polyurethane sponge attached to the front to spread the liquid.
To apply the composition, the applicator is held with the sponge pointing upward and the rear pressed against a sterile surface. This forces the rear, telescoping compartment onto the piercing device, which pierces the foil seal and releases the cyanoacrylate composition. The applicator is then inverted and the solution now soaks the sponge. The sponge is applied onto the incision site on the mammalian cadaver to apply a uniform coating of composition which, in situ, forms a polymeric film at this site.
In a particularly preferred embodiment, an applicator known as a xe2x80x9cpopulexe2x80x9d manufactured by Hardwood Products Company, LLC of Gilford, Me., USA is utilized.
Subsequent to polymer film formation, an incision is made at the site to excise the to-be-harvested tissue and/or organ. The harvesting procedure then occurs under conventional procedures well known in the art.
After harvesting is completed, the incision site and/or tissue/organ harvest sites are sealed by application of a prepolymeric cyanoacrylate composition so as to restore mechanical integrity to the cadaver and/or to prevent fluid leakage from these sites. In one embodiment, the prepolymeric cyanoacrylate composition used to seal the incision and/or harvest sites is the same as that used to form the polymeric film over the skin prior to incision. However, such is not necessary. For example, sealing of the incision site does not require use of a cyanoacrylate composition comprising an antimicrobial agent since the desired tissue and/or organ have been removed.
The cyanoacrylate compositions comprising the polymerizable cyanoacrylate esters are prepared by conventional methods of mixing the appropriate components until homogenous.
The specific viscosity of these compositions depends, in part, on the intended application of the composition. For example, relatively low viscosities are often preferred where application is to be made to a large surface area (e.g., abdominal surfaces). This preference results from the fact that those forms are less viscous and, accordingly, will permit more facile large surface area application of a thin application. Contrarily, where application is to be made to a specific position on the skin, higher viscosity compositions, including those containing thixotropic materials, are preferred to prevent xe2x80x9crunningxe2x80x9d of the compositions to unintended locations.
Accordingly, these compositions have a viscosity of from about 2 to 50,000 centipoise at 20xc2x0 C. Preferably the less viscous compositions have a viscosity of from about 2 to 1,500 centipoise at 20xc2x0 C. More preferably, the cyanoacrylate ester employed in these compositions is almost entirely in monomeric form and the composition has a viscosity of from about 2 to about 100 centipoise at 20xc2x0 C.
A thickening agent is optionally employed to increase the viscosity of the composition, which thickening agent is any biocompatible material which increases the viscosity of the composition. Suitable thickening agents include, by way of example, polymethyl methacrylate (PMMA) or other preformed polymers soluble or dispersible in the composition, a suspending agent such as fumed silica and the like with PMMA being preferred. Fumed silica is particularly useful in producing a gel for topical application having a viscosity of from about 1500 to 50,000 centipoise at 20xc2x0 C. Suitable thickening agents for the compositions described herein also include a partial polymer of the alkyl cyanoacrylate as disclosed in U.S. Pat. Nos. 3,654,239 and 4,038,345 both of which are incorporated herein by reference in their entirety.
The cyanoacrylate adhesive compositions may include a plasticizer and such plasticizers are included in the composition from about 10 to 30 weight percent and more preferably from about 18 to 25 weight percent based on the total weight of the composition absent any antimicrobial agent.
Additionally, the cyanoacrylate compositions described herein preferably include a polymerization inhibitor in an effective amount to inhibit premature polymerization of the composition during storage. In a particularly preferred embodiment, this inhibitor is sulfur dioxide which is employed at from about 50 to 500 ppm, preferably 50 to 200 ppm, based on the total weight of the composition absent any antimicrobial agent. Other preferred polymerization inhibitors include glacial acetic acid, free radical inhibitors (e.g., hydroquinones) and the like which can be used alone or in combination with SO2.
The polymerizable cyanoacrylate ester compositions may additionally contain one or more optional additives such as medicaments, colorants, perfumes, anti-diffusion agents, rubber modifiers, modifying agents, etc. In practice, each of these optional additives should be both miscible and compatible with the cyanoacrylate composition and the resulting polymer. Compatible additives are those that do not prevent the use of the cyanoacrylates in the manner described herein.
In general, colorants are added so that the polymer layer formed on the skin will contain a discrete and discernable color. Perfumes are added to provide a pleasant smell to the formulation. Rubber modifiers are added to further enhance the flexibility of the resulting polymer layer. Medicaments are added as necessary to achieve an antiseptic environment. The amount of each of these optional additives employed in the composition is an amount necessary to achieve the desired effect.
Preferred cyanoacrylate compositions useful in the practice of this invention are also disclosed by Greff, et al., U.S. Pat. No. 5,480,935, which application is incorporated herein by reference in its entirety. In a particularly preferred embodiment, the cyanoacrylate adhesive composition further comprises an antimicrobially effective amount of a compatible antimicrobial agent as disclosed, for example, in U.S. Pat. No. 5,684,042, which is incorporated by reference in its entirety. Such compositions preferably comprise from about 1 to about 40 and preferably 5 to 30 weight percent of the compatible antimicrobial agent either as a solution or as a suspension based on the total weight of the composition. Compatible antimicrobial agents are those which are either soluble or suspendable in the cyanoacrylate composition, which do not cause premature polymerization of the cyanoacrylate composition, which do not prevent polymerization of the cyanoacrylate composition when applied to mammalian skin, and which are compatible with the intended use. Suitable such compositions are disclosed in U.S. patent application Ser. Nos. 08/913,681 which discloses compositions of cyanoacrylate/povidone-iodine complexes and 09/215,078 which discloses compositions of cyanoacrylate esters/iodine complexes of polyoxyalkylene polymers. Both applications are incorporated herein by reference in their entirety.
In a particularly preferred embodiment, the compatible antimicrobial agent comprises a complex of iodine molecules with a biocompatible polymer. Such complexes are well known in the art and the resulting complex typically comprises both available iodine and iodide anions. These complexes, on contact with mammalian skin, provide for a source of antimicrobial iodine. In any event, such complexes are employed only as starting materials herein and, by themselves, do not form a part of this invention. Suitable biocompatible polymers include, by way of example only, polyvinylpyrrolidone polymer which, when complexed with iodine, is also referred to under the common name of povidone-iodine available from BASF, Mt. Olive, N.J., USA. When povidone-iodine is employed in the cyanoacrylate composition, preferably from about 5 to about 40 weight percent and more preferably from about 10 to 25 weight percent is added to the cyanoacrylate composition based on the total weight of the composition.
Other suitable antimicrobial agents include complexes of iodine molecules with poloxamers or copolymers of vinylpyrrolidone and vinyl acetate, copolymers of vinylpyrrolidone and vinyl acetate cross-linked with polyisocyanates, copolymers of vinylpyrrolidone and vinyl functionalities, polymers of pyrrolidone and the like.
The use of a compatible antimicrobial agent in the composition permits the agent to be released from the polymeric film thereby reducing microbial growth under the film.
One particularly preferred prepolymeric cyanoacrylate composition comprises ethoxyethyl cyanoacrylate containing about 0.5 weight percent 2-bromo-2-nitro-1,3-propanediol, 500 ppm hydroquinone and 100 ppm sulfur dioxide all based on the total weight of the composition.
The methods described herein are useful in forming a polymeric film over the site of incision during organ and/or tissue harvesting in a mammalian cadaver. The polymeric film finds particular utility in inhibiting microbial contamination at this site so as to reduce the incidence of infection in the harvested tissue and/or organ. Such mammalian cadavers preferably include human cadavers as well as animal cadavers suitable for xenotransplation such as pigs. The maintenance of the polymeric film over this site is expected to reduce the incidence of infection by inhibiting microbial contamination at this site.
In addition, the methods of this invention permit subsequent to harvesting of the tissue and/or organ, the sealing of the incision site and/or tissue/organ harvest sites by a prepolymeric cyanoacrylate composition so as to restore the mechanical integrity to the cadaver and/or to prevent fluid leakage from these sites.
The following examples illustrate certain embodiments of the invention but is not meant to limit the scope of the claims in any way.
Examples 1-2 below illustrate how the methods of this invention could be practiced. In these examples, the following abbreviations have the definitions set forth below. Unless defined, the terms have their generally accepted meanings. In addition, unless otherwise stated, all percentages are weight percentages based on the total weight of the composition.
g=gram
mL=milliliter
ppm=parts per million

Methods and compositions to enable the safe and effective harvesting of tissues and organs