Abstract:
The invention discloses a mammalian teat dip for controlling mastitis, a method for preparing the composition and a method of treatment of mammals. The composition contains a film-forming polymer blend and at least one antimicrobial. The polymer blend contains a solvent-soluble, thermoplastic polyurethane and a hydrophilic poly(N-vinyl lactam). Upon application to mammalian skin, this composition leaves a long-lasting, water-resistant, residual, elastic film which treats and protects mammalian skin from infection.

Description:
BACKGROUND OF THE INVENTION 
     The effective management and maintenance of large dairy herds and the production of dairy products has been a major agricultural accomplishment. One of the problems in maintaining large herds is the health of the individual animals. One health problem in individual animals of dairy herds which causes significant economic problems relates to mastitis. Often during milking, the skin of the dairy animal is irritated by automatic milking machines. This irritation, characterized by redness and occasionally areas of broken skin, can be the site of a microbial attack causing mastitis. Animals that contract mastitis must be removed from service resulting in the loss of the dairy output. As a result, a significant amount of attention has been focused on preventing the development of mastitis or treating mastitis in dairy herds. 
     The dairy farmer is faced with two different types of mastitis infections. Contagious mastitis is spread during the milking process through contact between the animal and dairy equipment that may carry a source of a mastitis pathogen. Contagious mastitis is most easily controlled using germicidal post milking teat dips. Such germicidal dips kill bacteria that are introduced onto the surface of the animal from the milking machines. The second type of mastitis, environmental mastitis, is caused by contamination of the animal surface by materials from the barn yard environment, fields, barn interior, etc. Such pathogens include  E. coli,  Streptococcus uberis, klebsiella and others. Such contamination occurs as the animal moves through its environment. Environmental mastitis is best treated with a barrier film that protects sensitive tissues from contamination. 
     In the treatment and prevention of mastitis the use of protective coatings, formed from aqueous coating systems, on the animals has been an option for many years. One class of coating compositions are actively antimicrobial and prevent the incidence of infection in the animal through the presence of an active biocide in the coating. Another class of coating materials are simply film barriers formed on the skin surface to prevent contact between vulnerable tissues and the environment. Many antimicrobial materials are incompatible with a variety of these polymeric or film forming materials. Recent product developments provide coatings for teat skin which form film barriers, as well as, contain antimicrobial agents. 
     In the typical operations of a dairy herd, the herd is brought into a milking station, the udder is washed to remove the barrier film. Any delay in removal of the film can substantially reduce productivity and substantially increase time required to deal with a large herd. Further, difficulty in removing the film can cause abrasion or bruising to the animal which can promote mastitis. Therefore, it is important that the films are easily removed in less than 15 minutes, preferably in less than 10 minutes, using water or mild cleaning solutions. In the periods between milking, the animal is released into the environment to graze. While grazing the animal is exposed to environmental water from dew, mud, rain and ponds. This exposure to water can cause the barrier film to rub off. 
     Among the materials used in barrier-type or film-type teat dips are solubilized liquids, polyvinylpyrrolidone and other vinyl polymers, protein hydrozylate, natural and synthetic gums, water, ethanol, methanol, isopropanol, soluble polymers, unsaturated fatty oils, cellulose derivatives, acrylic polymer lattices, etc. 
     Latex provides an effective covering of teat skin which can be combined with an antimicrobial agent (U.S. Pat. No. 4,113,854). However, the latex material has the serious drawback of not being readily removable when the next milking time arrives. The result can be a partially removed coating, leaving behind particles which become trapped in the milk line filters. The difficulties of removal can also result in excessive rubbing of the teat skin, thus leading to irritation. Furthermore the use of latex can potentially result in milk contamination. 
     On the other hand, teat dips which are easy to remove, for example, polyvinyl alcohol based teat dips, do not provide adequate water resistance. Such films do not remain on a dairy animal for the duration between milking periods. Due to exposure to water, these films wear off in about 3 to 4 hours. Without an adequate barrier film the dairy animal is vulnerable to environmental pathogens which will promote mastitis in the herd. 
     The following disclosures have been identified as part of the technology of the related art. Typical disclosures of disinfectant after-milking teat dips (aimed at destroying any pathogens remaining on the teats after milking) can be found in British Patent 1 144 637 (Kelco Chemicals, Ltd.), published on Mar. 5, 1969; Meave et al., J. Dairy Science, 52:6696 (1969); Dodd et al., ‘Mastitis Control,’ Biennial Reviews (1970) University of Redding, England, National Institute of Research of Dairying, pp. 21-57; Lentsch, U.S. Pat. No. 4,258,056; Lentsch et al., U.S. Pat. No. 4,376,787; Yang, U.S. Pat. No. 4,446,153; Marhevka, U.S. Pat. No. 5,017,369; Cantor et al., U.S. Pat. No. 3,728,449; Pankey, ‘Postmilking Teat Antisepsis,’ Symposium on Bovine Mastitis, Veterinary Clinics of North America: Large Animal Practice, Vol. 6, No. 2, July 1984; Pankey et al., ‘Efficacy Evaluation of Two New Teat Dip Formulations Under Experimental Challenge,’ Journal Dairy Science, 68:462-465 (1985), Philpot et al., ‘Hygiene in the Prevention of Udder Infections. V. Efficacy of Teat Dips Under Experimental Exposure to Mastitis Pathogens,’ Journal Dairy Science, 61:956-963 (1978), Bennett, ‘Teat Dip as a Component of Coliform Mastitis Control, Dairy and Food Sanitation,’ Vol. 2, No. 3, pp. 110-114 (March 1982), Eberhart et al, ‘Germicidal Teat Dip in a Herd with Low Prevalence of Streptococcus agalactiae and Staphylococcus aureau Mastitis,’ Journal Dairy Science, 66:1390-1395 (1983). 
     Typical disclosures of protective or barrier-type teat dips can be found in Loosemore et al., U.S. Pat. No. 5,641,498, Schmidt et al., U.S. Pat. No. 5,503,338, Acres et al., U.S. Pat. No. 3,066,071, Krause, U.S. Pat. No. 3,222,252, Philpot et al., Journal Dairy Science, 58:205-216, Coughman et al., U.S. Pat. No. 3,993,777, Pugliese, U.S. Pat. No. 4,049,830, Silver et al., U.S. Pat. No. 4,199,564, Dybas et al., U.S. Pat. No. 4,311,709 and Andrews et al., U.S. Pat. No. 4,113,854. Still also for examples of such materials, see Farnsworth, Journal of American Veterinary Medical Association, 177:441 (1980) and Farnsworth et al., The Bovine Practitioner, No. 16, pp. 28-29 (1981). Still further, please review Canadian Patent No. 1,065,254 and European Published Application No. 25,640 (Mar. 25, 1981). 
     A substantial need exists for an antimicrobial and barrier teat dip that can be easily and rapidly removed during milking operations while imparting sustained water resistance between milking periods. 
     SUMMARY OF THE INVENTION 
     The present invention is a new mammalian teat dip composition as well as a method for treating mammalian skin. This film-forming composition exhibits antimicrobial properties against the typical contagious mastitis causing pathogens and barrier properties protecting the animal from environmental mastitis. 
     This aqueous based composition includes a solution of a water-resistant, film forming, polymer blend and at least one antimicrobial agent. Examples of antimicrobial agents include iodine, chlorhexidene, bronopol and triclosan. Upon application to a substrate, this composition leaves a long-lasting, water-resistant, residual, elastic film which treats and protects mammalian skin from infection. 
     In one formulation the iodine-containing antimicrobial agent is added as an aqueous solution of polyvinylpyrrolidone-iodine (PVP-I 2 ). In another formulation the iodine-containing antimicrobial agent is added as an aqueous solution of iodine metal and iodide salts. In yet another formulation the iodine-containing antimicrobial agent is added as an aqueous solution of iodine metal, hydriodic acid, and a surfactant. The surfactant can range widely in its degree of ionization, including no ionization. 
     The chlorhexidine-containing antimicrobial agent can be added as an aqueous solution of chlorhexidine salts. 
     The polymer blend, as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.), consists essentially of two polymer components. One polymer component is an organic, solvent-soluble, preformed, thermoplastic polyurethane which has no reactive isocyanate groups. The other polymer component is a hydrophilic poly(N-vinyl lactam). This polymer blend is capable of withstanding exposure to water without a significant loss of the hydrophilic poly(N-vinyl lactam). 
     The polyurethane of the polymer blend can be derived from an aromatic polyisocyanate and a polyether polyol; or from an aliphatic polyisocyanate and a polyether polyol; or from an aromatic polyisocyanate and a polyester polyol; or from an aliphatic polyisocyanate and a polyester polyol. 
     The poly(N-vinyl lactam) of the polymer blend is a water-soluble polyvinylpyrrolidone homopolymer or a poly(N-vinyl caprolactam) homopolymer. 
     The polymer blend may contain at least one additional compatible polymer component. The additional polymer component is a homopolymer or copolymer of at least one monomer selected from the group consisting of alpha-olefin, vinyl chloride, vinylidene chloride, hydroxyethylmethacrylate, acrylic acid, methacrylic acid, vinyl acetate, vinyl alcohol, and vinyl ether. 
     The composition may also contain water-soluble or water-dispersible skin conditioning agents, such as glycerin; glycols; polyols, such as polyethylene glycol; lanolin; aloe vera and vitamins. The composition may also contain colorants, fragrances and insect repellants. 
     The present invention also provides a method of protecting a mammalian teat from infection. This method includes applying the composition to the mammalian teat and evaporating the solvent portion of the composition to form a protective water resistant film. 
     The instant composition in addition to protecting the animal from contamination and allowing easy removabilty prior to milking, provides an increased resistance to premature loss. Thus, when an animal is released into the environment, the composition will be resistant to environmental water, remaining on the animal for the period between milkings. Unlike polyvinyl alcohol-based formulations which wear off in about 3 to 4 hours, the instant invention imparts water resistance up to 8 hours. Moreover, when the animal returns to the milking site, the antimicrobial barrier coating can be easily removed in about 5 minutes using an aqueous wash. Milking can continue without delay and after milking is finished, the animal can again be treated with the aqueous material forming a new antimicrobial barrier film. 
     DETAILED DESCRIPTION 
     The aqueous compositions and the resulting films of this invention provide barrier layers containing antimicrobial agents which prevent the contact between the animal skin and microorganisms either from the environment or from other animals. These films provide extended water resistance without compromising the ease of removability necessary to run a productive dairy operation. This invention also discloses a method of protecting mammalian teat skin from infection. 
     The novel aqueous mammalian teat dip composition includes a solution of a water-resistant, film-forming polymer blend and at least one antimicrobial agent. The composition contains an amount of the polymer sufficient to form a water-resistant film upon topical application. The antimicrobial agent is present in the composition in an amount which is sufficient to protect mammalian skin from infection by typical contagious and environmental mastitis-causing pathogens. Upon application to a substrate, this composition forms a water-resistant, residual, elastic film. 
     The composition can include 50% to 95% water; 0.01% to 2.0% of a thickener; 0.1% to 20% of a water-resistant, film forming, polymer blend; up to 10% of an aqueous acid; up to 10% of an aqueous base and about 0.05% to 5% of an antimicrobial agent. Examples of antimicrobial agents are iodine, chlorhexidene, bronopol and triclosan. The composition may also include 0.05% to 10% of one or more water-soluble or water-dispersible skin conditioning agents. 
     One preferred antimicrobial agent of the invention is an aqueous solution of iodine (AST, Inc.). A formulation of this aqueous solution contains 50% to 99% water, 0.1% to 50% iodine metal, and 1% to 50% iodide salts. Another formulation of this aqueous solution contains 50% to 99% water, 0.1% to 50% iodine metal, 1% to 50% hydriodic acid, and 1% to 50% of a surfactant. The surfactant can be cationic, anionic, non-ionic or any combination of these. Iodine can also be added as a powder of polyvinylpyrrolidone-iodine (PVP-I 2 ). The aqueous solution formed from PVP-I 2  powder contains 50% to 99% water and 20% to 99% PVP-I 2 . 
     Another preferred antimicrobial agent of the invention is chlorhexidine. Chlorhexidine may be added as an aqueous solution which includes 50% to 99% water and 0.1% to 50% chlorhexidine salts. 
     The polymer blend used in the instant invention is taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.). It consists of essentially two polymer components. One polymer component is an organic, solvent-soluble, preformed, thermoplastic polyurethane having no reactive isocyanate groups. The other polymer component is a hydrophilic poly(N-vinyl lactam). This polymer blend is capable of withstanding exposure to water without significant loss of the hydrophilic poly(N-vinyl lactam). 
     The polyurethane of the polymer blend can be derived from an aromatic polyisocyanate and a polyether polyol; or from an aliphatic polyisocyanate and a polyether polyol; or from an aromatic polyisocyanate and a polyester polyol; or from an aliphatic polyisocyanate and a polyester polyol. 
     The poly(N-vinyl lactam) of the polymer blend is a water-soluble polyvinylpyrrolidone homopolymer or a poly(N-vinyl caprolactam) homopolymer. 
     The polymer blend may contain at least one additional compatible polymer component. The additional polymer component is a homopolymer or copolymer of at least one monomer selected from the group consisting of alpha-olefin, vinyl chloride, vinylidene chloride, hydroxyethylmethacrylate, acrylic acid, methacrylic acid, vinyl acetate, vinyl alcohol, and vinyl ether. 
     These blends exhibit properties intermediate those of the polyurethane component and those of the poly(N-vinyl lactam) component. Blends which are predominantly made up of the hydrophilic poly(N-vinyl lactam) component readily absorb water to become soft and slippery. Blends which are predominantly made up of the polyurethane component are relatively hard but still wettable. Exhibiting properties intermediate of those of polyurethane and poly(N-vinyl lactam) enables the dual characteristic of the present invention. Though capable of being removed easily, the present invention provides sustained water resistance. 
     Exposure of the claimed compositions to water, even for prolonged periods, does not result in any significant loss of the hydrophilic poly(N-vinyl lactam) component, possibly as a result of associative forces with the polyurethane component, chain entanglement, or both. Whatever may, in fact, be the basis for this property, this property contributes to the ability of the composition to remain on dairy animals despite prolonged contact with environmental water. 
     Since the polyurethane is a preformed polymer having no reactive isocyanate groups, it is stable in solution for indefinite periods of time. Accordingly, polymer products of the instant invention can be readily formed at the point of application as needed simply by evaporating any solvent(s) with which they may be associated. This versatility makes the instant products especially convenient for use as coatings. 
     The composition can be applied to the dairy animal in a variety of ways. The material can be sprayed, brushed, dabbed, or flooded onto the susceptible sites. One common application mode is by means of a dip. The composition is placed in a small container with a shape adapted to the teat. The teat is then dipped into the container filled with the aqueous composition. 
     The composition may contain various viscosity enhancers or thickeners. The thickener causes aqueous compositions to cling to the surface skin of the animal and enables the composition to resist waste through excessive dripping. Thus, the composition remains in place until it is dry and the barrier layer is formed. In its preferred embodiment, the viscosity of the composition ranges from about 1-1500 cP. This range in viscosity allows an adequate amount of the composition to remain on the mammalian teat when applied without being overly viscous which would make application difficult by dipping or other methods. Thickeners which may be used in the present invention include natural gums such as xanthan gum (Keltrol TF, Keltrol). 
     After the mammalian teats have been coated with the composition of this invention, the resulting coating is permitted to dry to an adherent solid film on the teats. Typically, some of the still liquid coating material flows down to the teat end where a plug-like deposit is formed. This deposit or plug also dries to form an adherent solid. This plug is capable of sealing off the teat canal. 
     The protective barrier formed on the mammalian skin is a residual, elastic film, that is water-resistant, when applied to these skin surfaces. The film is flexible, longlived and resists cracking. The film contains the antimicrobial material that kills microorganisms on the skin surface. Such antimicrobial action is important because the milking operation can often spread mastitis causing microorganisms which can under certain circumstances cause inflammation and infection in abraded or affected skin resulting from contact with milking machines during milking operations. Additionally, the barrier film also protects the mammalian skin from mastitis-causing organisms between milkings. The films of this invention are highly water-resistant. They can remain on the mammal for up to eight hours despite exposure of the animal to environmental water such as rain, dew, ponds, mud, etc. In contrast, polyvinyl alcohol-based formulations wear off in about three to four hours. 
     Surprisingly, despite the highly water-resistant feature of this composition, the film and the plug are removable without tedious physical steps. A few minutes of a warm-water wash with a mild surfactant is fully effective for the removal of the film. 
     The composition can also contain water-soluble or water-dispersible skin conditioning or moisturizing agents which do not degrade barrier properties. The preferred range of these agents in the composition is 0.05% to 10%. Examples of these ingredients are glycerin; glycols; polyols, such as polyethylene glycol; lanolin; aloe vera and vitamins, such as E, C and A. These agents serve to assist in soothing and retaining moisture on the skin. 
     Agents such as colorants, fragrances and insect repellants (e.g., citronella) may also be included in the composition. 
     Buffering agents utilized in this invention include the acid form and base salt of an organic or inorganic acid in such a ratio to produce a resultant pH value for the finished composition from about 4.0 to 8.0. 
     The following examples are illustrative of the composition of this invention and provide a best mode. 
    
    
     EXAMPLES OF THE INVENTION 
     Example 1 
     To 89.5 grams of water was added 0.5 grams of xanthan gum (Keltrol TF, Keltrol) with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogeneous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. The solution does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water-resistant which prevents the spread of mastitis causing organisms. 
     Example 2 
     To 86.7 grams of water was added 1.4 grams of citric acid (Fischer Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.5 grams xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogeneous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. A solution of pH approximately 5.0 does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 3 
     To 90.4 grams of water was added 1.4 grams of citric acid (Fisher Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.1 grams xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer Inc.) was added with stirring until homogenous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. A solution of pH approximately 5.0 does not drip when sprayed on a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 4 
     To 94.3 grams of water was added 0.5 grams of xanthan gum (Keltrol CGT, Keltrol) with stirring. The solution was mixed until homogeneous, then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer Inc.) with stirring until homogeneous. Next, 0.2 grams bronopol (Inolex Chemical) was added and the solution mixed until well blended. The solution does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 5 
     To 91.9 grams of water was added 0.1 grams of poly(ethylene oxide) (Americhol) with stirring. The solution was mixed until homogeneous, then 5.0 grams of a hydrophilic polymer blend, as taught by U.S. Pat. No. 4,642,267 (Hydromer Inc.),was added with stirring until homogeneous. Next, 3.0 grams of an aqueous chlorhexidene gluconate solution was added and mixed until well blended. The solution does not drip when sprayed onto a plate and held vertically, and films cast from the resulting solution are elastic and water-resistant which prevents the spread of mastitis causing organisms. 
     Example 6 
     To 94.0 grams of water was added 0.5 grams of xanthan gum (Keltrol CGT, Keltrol) with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend, as taught by U.S. Pat. No. 4,642,267 (Hydromer Inc.), was added with stirring until homogeneous. Next, 0.5 grams of triclosan (Ciba Speciality Chemicals) was added and the solution was mixed until dispersed. The solution does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms 
     Example 7 
     To 86.7 grams of water was added 1.4 grams of citric acid (Fisher Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.5 grams of xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogeneous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. A solution of pH approximately 5.0 does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 8 
     To 74.7 grams of water was added 1.4 grams of citric acid (Fischer Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.5 grams xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogeneous. Next, 17.0 grams PVP-I 2  was added and the solution was mixed until well blended. A solution of pH approximately 5.0 does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 9 
     To 86.2 grams of water was added 1.4 grams of citric acid (Fischer Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.5 grams of xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogenous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. Finally, 0.5 grams of aloe vera (Terry Labs) was added and mixed until homogeneous. A solution of pH approximately 5.0 does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     Example 10 
     To 81.7 grams of water was added 1.4 grams of citric acid (Fischer Chemical Company) with stirring. Once dissolved, 1.5 grams of 6 molar sodium hydroxide was added to bring the pH to approximately 6.0. Next, 0.5 grams of xanthan gum (Keltrol CGT, Keltrol) was added with stirring. The solution was mixed until homogeneous. Then 5.0 grams of a hydrophilic polymer blend as taught by U.S. Pat. No. 4,642,267 (Hydromer, Inc.) was added with stirring until homogenous. Next, 5.0 grams of an aqueous iodine solution (AST Inc.) was added and the solution was mixed until well blended. Finally, 0.5 grams of glycerin (Aldrich Chemical) was added and the solution mixed until homogeneous. A solution of pH approximately 5.0 does not drip when cast onto a plate and held vertically, and films cast from the resulting solution are elastic and water resistant which prevents the spread of mastitis causing organisms. 
     While the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in this art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications can be made to adapt a particular situation, material or composition of matter, process, process step or steps, or then-present objective to the spirit of this invention without departing from its essential teachings.