A microbe-inhibiting (MI) compound is incorporated into a biodegradable polymer composition, most preferably, a starch-based polymer, to inhibit microbial growth and to attenuate the biodegradation of the polymer composition. Such a composition is used to manufacture any of a number of articles, particularly those that come in contact with foods such as foam containers and fruit shock absorber nets as well as packing materials such as loose fill pellets.

1. Field of the Invention
The present invention is in the field of biodegradable polymers and articles manufactured therefrom, which polymers include a microbe-inhibiting agent.
2. Description of the Background Art
Degradable polymers have found applications in diverse areas such as garbage bags, golf tees, food containers, foamed packing materials, chewing articles for pets, and even writing pens. Degradable polymers can be chosen for an application for many different reasons, including their tendency to break down under appropriate biological or disposal conditions, their ability to serve as a digestible or otherwise harmless mastication material for people or animals, or for public relations purposes.
A common class of biodegradable polymers is starch-based. Pure starch polymers do not possess the desired properties for most applications, as they are brittle and are unduly affected by moisture. They are therefore commonly blended and/or reacted with other polymers. U.S. Pat. No. 5,321,064 describes a class of biodegradable polymers in which starch is reacted with synthetic polymeric material such as polyethylene, polystyrene, polypropylene and polyvinyl chloride. U.S. Pat. No. 5,409,973 describes a class of materials based on starch and an ethylene copolymer. U.S. Pat. No. 5,360,830 describes a similar material produced in expanded form. U.S. Pat. No. 5,459,258 describes a class of biodegradable materials based on the combination of hydrophobic polysaccharides, one thermoplastic and the other non-thermoplastic.
Biodegradable starch-based resins are available commercially from a number of manufacturers, such as Starchtech(trademark) and Novamont(trademark). Starchtech(trademark) sells a series of such polymers under the xe2x80x9cRe-NEW(trademark)xe2x80x9d trade name. Novamont(trademark) offers several classes of such polymers under the trade name, xe2x80x9cMater-Bi(trademark).xe2x80x9d
Biodegradable poly(lactic acid) (PLA) and poly(glycolic acid) (PGA) resins, as well as PLA-PGA copolymers have numerous desirable properties. (See: Ratner, BD et al., Eds., Biomaterials Science, Academic Press, New York, 1996, p. 64; Naitove, M., Plastics Technology, March 1995, p. 15.) A variety of commercial grades are available from Cargill, under the name xe2x80x9cEcoPLA(trademark),xe2x80x9d and also from various biomedical suppliers. Adjustment of the PGA:PLA ratio in a material can be used to fine-tune the texture, degree of hydrophilicity and rate of biodegradation. For example, PGA is more hydrophilic than PLA, so that increasing the PGA content will increase the hygroscopic property (uptake of water, saliva, or any other fluid). In addition, although PGA is highly crystalline, which generally slows its degradation, it becomes markedly less crystalline, and more degradable, when blended with PLA.
Materials based on polyhydroxybutyrate (PHB) are also attractive. One example, available commercially under the name Biopol(trademark) comprises a blend with 3-hydroxyvaleric acid (PHV). PHB is generally highly crystalline, inflexible, and difficult to process. Blending with PHV diminishes the crystallinity, resulting in more flexible, more easily processed materials.
Polycaprolactone, either pure or blended with other materials, is a generally attractive degradable material that has found uses in medical applications such as sealing materials for wounds.
Other attractive degradable materials include, the poly(amino acids), the polyanhydrides, poly(ortho esters), and polyphosphazenes.
The mechanism by which the materials of interest are degraded typically involves the metabolic or digestive action of microbes or enzymes generally derived from those microbes breaking down the molecular structure or catalyzing the hydrolysis of the materials. In many cases, however, significant hydrolysis occurs in the absence of direct microbial or enzymatic action.
The deliberate exposure of degradable materials to microbial or digestive conditions, such as in composting or mastication, is expected to bring about their relatively rapid degradation. Unfortunately, however, such materials are naturally susceptible to microbial action over their entire lifetime. Articles constructed from biodegradable materials therefore may support microbial growth long before they are degraded or otherwise consumed. Biodegradable materials often readily absorb water which generally promotes microbial growth. This property may be a serious problem for materials requiring prolonged storage, especially if the storage environment is humid or otherwise encourages growth of fungi or bacteria (e.g., dark, poor ventilation, dirt, etc.). This is an especially serious problem for materials that are particularly intolerant of microbial proliferation, such as materials designed to contact food. Examples of the latter include plastic cutlery and tableware, plastic or paper/plastic composite cups, plastic or paper/plastic composite food containers, etc. Items the use of which involves contact with warm, dirty, and/or humid conditions are also particularly at risk, such as chewing articles for pets.
U.S. Pat. No. 5,744,516 describes biodegradable resin molded articles made from biodegradable resin raw material, a biodegradable additive and an additive made of a substance existing in the nature. Also disclosed are (a) injection molded articles made of a biodegradable resin and an anti-biotic substance, and (b) resin molded articles having a layer of a biodegradable resin, and a layer of a photolytic resin covering the resin layer and also containing an antibiotic. This document states that prolonged use of a biodegradable resin requires first that degradation by bacteria be restricted, as by adding an antibiotic to the resin (citing Japanese Unexamined Patent Publication (Kokai) No. 5-51073).
It is often desirable to fine-tune (or even to reduce markedly) the degree of biodegradability of a polymer. For blended or reacted biodegradable polymers, this can be accomplished by altering the proportion of, and/or degree of, reaction with the expressly biodegradable component. Characteristics of the polymerization (e.g., degree of branching, cross-linking, etc.) can be varied or a protective coating added. These techniques for adjusting the degree of biodegradability, however, suffer from the fact that they often require complex engineering and can have unwanted side effects on useful properties (e.g., strength, impact resistance, processability, UV- or heat-resistance, etc.). There is thus a need for a simple way to alter the degree of biodegradability of a polymer without affecting other desirable properties.
The present invention provides a simple approach to altering the biodegradability of a polymer without affecting other properties and thereby overcomes the shortcoming of the prior art.
The invention provides compositions and methods that incorporate an effective amount of a microbe-inhibiting (MI) compound or cocktail of compounds (all of which are referred to herein interchangeably as xe2x80x9ccompoundxe2x80x9d or xe2x80x9cagentxe2x80x9d) into a biodegradable polymer, most preferably, starch-based polymers. The starch can be complexed with synthetic organic polymeric materials such as polyethylene, polypropylene and copolymers of ethylene and propylene. The synthetic polymers are preferably linked to the starch by organic linkers such as maleic anhydride. Such polymers linkers are described in U.S. Pat. No. 5,321,064, which is incorporated herein by reference. This patent describes a class of biodegradable polymers in which starch is reacted with synthetic polymeric material such as polyethylene. Although post-incorporation of the agent can be effective (e.g., via soaking or high-pressure impregnation), it is preferred to incorporate the agent into the structure of the polymer at the time of compounding or at the time of formation (e.g., molding) of the final polymer article.
Desirable MI agents can be obtained in various forms, e.g., as a relatively pure powder, a liquid concentrate, in a resin carrier where the carrier is one of the components of a desired blend.
For the most part, the preferred MI compounds or cocktails of compounds are effective against a broad range of microbes, particularly fungi and bacteria, and have a number of other desirable properties, including: safe at and above the concentrations required for use; degradation temperatures appreciably higher than the typical processing temperatures of the desired host plastics; when interacting with host plastic, do not lower their own degradation temperature or that of the host plastic; are readily dispersed in the plastic; and readily diffuse in the plastic.
The polymers containing the MI compounds are used to manufacture any of a number of articles, preferably ones that come in contact with foods such as foam containers and fruit shock absorber nets. Also intended are loose fill pellets.
In one embodiment of the invention, a biodegradable organic polymer composition for forming useful articles comprises a host polymer that has incorporated therein an effective amount of a MI compound that inhibits growth of microbes in or on the article formed with the composition during the useful life of the article, thereby retarding degradation of the composition and the article during its useful life. In a preferred embodiment, the host polymer includes starch.
The MI compound preferably has at least one of antifungal and antibacterial activity. The concentration of the MI compound is between about 0.001% and about 3% by weight in the polymer, more preferably between about 0.005% and about 1% by weight.
When the MI compound is in particulate form in the host polymer, the microbe-inhibiting compound is in a solid phase at a concentration that is preferably between about 1.5 and about 1000 times the MI compound solid phase minimal inhibitory concentration, more preferably, between about 5 and about 300 times the MI compound solid phase minimal inhibitory concentration (xe2x80x9cMICxe2x80x9d).
When the MI compound is substantially in solution in the host polymer, the microbe-inhibiting compound is preferably at a concentration between about 1 and about 20 times the microbe-inhibiting compound""s solid phase MIC, more preferably, between about 2 and about 20 times the MIC.
In the above composition, the host polymer preferably comprises a synthetic organic polymer, preferably one selected from the group consisting of polyethylene, polypropylene, a copolymer of ethylene and propylene, polystyrene, polyvinyl chloride, polyhydroxybutyrate, polyhydroxybutyrate blended with 3-hydroxyvaleric acid, polycaprolactone, a poly(amino acid), a polyanhydride, a poly(ortho ester), and a polyphosphazene.
When starch is included, it is preferably linked to the synthetic organic polymer by an organic linker group, preferably maleic anhydride.
In the above composition, the MI compound retards degradation partially or completely during storage of the article.
The MI compound above is preferably selected from the group consisting of diiodoethyl-p-tolylsulphone (DIMTS), triclosan, 10,10xe2x80x2-oxy-bis-phenoxarsin)); a tributyltin derivative Intercide(trademark); (N-(trichloromethylthio)phthalimide); copper-bis-(8-hydroxyquinoline); (N-trichloromethylthio)-4-cyclohexene-1,2-dicarboximide; 2-N-octyl-4-isothiazolin-3-one; a zinc complex of pyrithione termed Zinc Omadine; and silver hydroxyapatite. Preferred forms of triclosan are Irgasan DP-300(trademark) or Ultrafresh NM-100(trademark). The MI compound can be a cocktail of antimicrobial agents.
In a preferred starch-based composition, the synthetic polymer is maleated ethylene-propylene copolymer and the MI compound is DIMTS.
In another embodiment of the invention, an article of manufacture is formed from the biodegradable organic polymer compositions described above. The article can be molded or extruded. Preferably, the article is one which, in its normal use, contacts a food. Thus, the article can be selected from the group consisting of a foam food container or support, a shock absorber net, a loose-fill foam packing pellet, a cutlery or tableware article and a drinking cup. The article can also be selected from the group consisting of a loose-fill foamed packing pellet, a pet chewing article; a garbage bag and a golf tee.
In another embodiment of the invention, a method for retarding the undesired degradation of a biodegradable organic polymer composition that is optionally formed into a useful article comprises incorporating into the polymer an effective amount of a MI compound that inhibits growth of microbes in or on the composition or article. In this method, the polymer composition preferably includes starch.
Still further according to the invention, a method of rendering a biodegradable organic polymer composition, or a useful article formed therefrom, resistant to microbial invasion, growth, proliferation or spread comprises incorporating into the organic polymer composition, preferably one that includes starch, an effective amount of a MI compound.
In the foregoing method, the MI compound can be in the form of a powder, a liquid concentrate or can be first incorporated or integrated into a resin carrier. Incorporation of the microbe-inhibiting compound into the polymer can be performed at the time of compounding the polymer or at the time of forming the article.
In this method, the MI compound can be in particulate form, wherein the incorporating comprises the steps of dry-mixing, heating and, optionally, further mixing the microbe-inhibiting compound and the polymer. The incorporating can comprise a step of extruding, processing in a mixer or milling in a rolling mill.
In a preferred method, the composition is formed by the steps of:
(a) mixing 100 parts of dry starch with 40 parts of maleated ethylene-propylene copolymer, to form a first mixture;
(b) blending the first mixture with 4 parts of a carrier resin comprising 6% MIMTS in ethylene vinyl acetate, to form a second mixture; and
(c) mixing the second mixture in an internal hot mixer for 14 minutes at 180xc2x0 C.
A microbe-inhibitory (MI) compound is one that inhibits the growth, proliferation, spread, of any of a number of microorganisms, most importantly fungi (especially mold and yeast) and bacteria as well as algae, protozoa and various microscopic parasitic organisms. The most preferred compounds act in a manner that is not selective for any particular organism, but rather are inhibitory to a broad spectrum of microbial agents. The microbe-inhibiting compound can act by any mechanism to inhibit growth of the organisms, whether biostatic or biocidal. The preferred compounds are not required to have a particular inherent level or threshold of activity to be useful in accordance with this invention. In general, the preferred MI compounds are not the highly selective antibiotics of the type used in human medicine.
One objective of incorporating the MI compound is to arrest partially or completely the biodegradation of the polymer material.
In some cases, it is desired that the degradable compositions of the present invention, particularly when formed into an article, resist degradation for a desired period of time, preferably the useful life of the article. After that interval, it may be desirable for the composition to degrade at a rate it would have without the presence of the MI compound. In such cases, a preferable MI compound is one that gradually becomes deactivated, either by its interaction with microbes or by its interaction with other environmental factors such as ambient water vapor. MI compounds that lose their activity over time are well-known in the art, and include some that are specifically described herein. In such cases, the quantity of the MI compound in the composition, and its spatial and temporal distribution within the article, combine with the characteristics of the use environment of the article to determine the effective rate of degradation and, thereby, the lifetime of the composition and article.
For large-scale waste disposal, it is often desired that polymer-based materials possess low incineration energy, meaning that they release comparatively little energy when they are combusted. Degradable materials, which often possess characteristically low bond energies, are good candidates as components in low-incineration energy materials. Such materials, however, are frequently susceptible to microbial degradation, and their useful life may therefore be unduly shortened as they are exposed to environmental sources of fungi or bacteria. For example, in a humid environment, molds may grow on a degradable material or degradable component of a composite material. This phenomena is frequently observed with starch-based plastics materials of the type the invention seeks to improve. An example of starch-based plastics materials is starch-based packing xe2x80x9cpeanutsxe2x80x9d which may possess an unduly short shelf life in a warm and humid storage environment.
The present invention provides a means to arrest the potential for such undesired degradation by incorporating a MI compound into the starch-based (or other) polymer. One criterion for selection of such a compound is that it not add appreciably to the incineration energy of the final material.
A preferred MI compound is diiodomethyl-p-tolylsulphone (xe2x80x9cDIMTSxe2x80x9d). Paulus, W., Microbicides for the Protection of Materials, Chapman and Hall, 1993, which is hereby incorporated by reference, describes this and other biocidal and biostatic agents. This compound possesses a broad spectrum of anti-microbial activity, and is most active against fungi (including yeast) and algae. DIMTS is especially preferred in articles that may be partially or wholly digested or in cases where the article is in contact with materials which are to be digested.
DIMTS can cause yellowing in the final article, and if this is deemed unattractive, color suppressants can be added. DIMTS melts at about 157xc2x0 C. It is relatively insoluble in water (0.0001 g/L at 25xc2x0 C.). Acetone (350 g/L at 25xc2x0 C.) and ethanol (20 g/L at 25xc2x0 C.) are preferred solvents. DIMTS is generally stable over a pH range of about 4-10. A preferred form of DIMTS is the product Ultrafresh UF-95(trademark), available from Thomas Research Associates. The concentration of UF 95(trademark) in the finished product should be between about 0.001% to 3%, preferably between about 0.01% and 1% by weight per cent. (Unless otherwise specified, all concentrations disclosed herein are given in weight %).
Triclosan (2,4,4xe2x80x2-trichloro-2-hydroxydiphenylether), another preferred MI compound, is sold by Ciba-Geigy under the trade name Irgasan DP-300(trademark). It can be obtained as a crystalline powder or as a liquid concentrate. It is also available from Thomas Research Associates under the trade name Ultrafresh NM-100(trademark) in a commercial form ready for compounding. Unmodified triclosan is insoluble in water; sparingly soluble in dilute alkali solution; and soluble in ethanol. It melts at about 60xc2x0 C., and decomposes at about 285xc2x0 C. It has an LD50 oral toxicity of  greater than 5000 mg/kg for dogs. It is non-mutagenic, non-teratogenic and has good skin compatibility. Data for triclosan, along with that for many other MI agents, are given in Paulus, supra.
Ultrafresh NM-100(trademark), a preferred form of triclosan, is added in quantities to achieve a final concentration in finished product between about 0.001% and 2%, preferably between about 0.004% and 0.3% by weight.
Other preferred MI compounds include Vinyzene(trademark) (OBPA (10,10xe2x80x2-oxy-bis-phenoxarsin)); Intercide(trademark) (a tributyltin derivative); Fungitrol(trademark) (N-(trichloromethylthio)phthalimide); Cunilate(trademark) (copper-bis-(8-hydroxyquinoline); Vancide(trademark) (N-trichloromethylthio)-4-cyclohexene-1,2-dicarboximide); Micro-Chek(trademark) (2-N-octyl-4-isothiazolin-3-one); Zinc Omadine (a zinc complex of pyrithione); and Apacider(trademark) (silver hydroxyapatite).
In many cases, consumers may prefer articles that include or have been treated with natural MI agents. Garlic and turmeric are preferred sources of such materials, e.g., in the form of extracts or concentrates, but other natural spices or additives known in the art can be used as well.
In a preferred embodiment, the MI compound in particulate form is dry-mixed with the host polymer to obtain a relatively homogeneous overall mixture. Subsequent heating and further mixing serve to intermix the materials on a still finer level, e.g., the MI compound should come to exist as a solution or as a fine dispersion in the host polymer. Further mixing and homogenization can occur via shearing processes that occur to varying degrees during subsequent extrusion or processing with mixers (e.g., Banbury mixer) or rolling mills (e.g., the two-roll mill). This material can then be formed into pellets or some other form suitable for use in forming the final article.
It is generally preferred first to form a resin in which the MI compound is highly concentrated. The final article can be formed simply by mixing this resin with the conventional resin (lacking the MI compound) just before molding. For example, the resins can be mixed in the hopper of an injection molding machine. In this case, the host (or carrier) material containing the concentrated MI agent preferably comprises material which is similar to, or otherwise compatible with, at least one of the material(s) which are to comprise the final article. In any case, the carrier material is selected to be stable and not affect degradation or otherwise adversely affect any other important or desirable property of any material in the final article.
Because the concentration of the MI compound in the concentrated resin may far exceed that commonly used, the MI compound may be incompatible with the desired carrier material. For compatibility, the carrier material is often chosen to be, in large part, the same material as one of the base polymers of the final article. When the substances are incompatible, the MI agent will often be xe2x80x9crejectedxe2x80x9d by the carrier material, resulting, e.g., in xe2x80x9cblooming.xe2x80x9d U.S. Pat. No. 4,789,692 (incorporated by reference) describes a method of incorporating very high concentrations of biocides into thermoplastic resins so that the biocides are highly stable (or xe2x80x9cimmobilizedxe2x80x9d). The method essentially involves forming a composite resin comprising one phase which is identical to that of the final article and another phase that is highly compatible with the MI compound, which compound can be highly concentrated in this latter phase.
Solubility and/or general compatibility of the MI compound in the host polymer are important. A MI compound that is highly soluble in the host polymer can be dispersed on a molecular scale resulting in a true homogeneous distribution. A MI compound that is poorly soluble in the host polymer can be dispersed as a particulate in that polymer. As used herein, xe2x80x9cparticulatexe2x80x9d refers to any condensed or bonded phase which covers a spatial scale significantly greater than the microbe-inhibiting compound""s molecular size. The term xe2x80x9cparticulatexe2x80x9d does not imply any shape or aspect ratio of the particles (i.e., they are not required to be approximately spherical or to have an aspect ratio near one).
Again, because a MI compound does not always dissolve fully, it can exist as xe2x80x9cclumpsxe2x80x9d or particulate form in the polymer. In such cases, the actual concentration of the MI compound will vary across the composition of polymer. The xe2x80x9ceffective concentrationxe2x80x9d of a MI agent is a concentration (by volume) that would be present in the polymer if the agent were fully dissolved and dispersed. Thus, for example, stating that a polymer has an effective MI compound concentration of 0.01% may indicate that
(a) the MI agent is dissolved uniformly at a volume concentration of 0.01% (v/v), or
(b) the MI compound is present in {fraction (1/100)}th of the polymer volume (i.e., in the form of particles) at a concentration of 1% (v/v), whereas the remaining 99% of the polymer has no MI compound (0%), for example, because diffusion has not yet occurred.
Several factors must be considered when the MI agent exists as a dispersed particulate in the host polymer. If the particulate is highly stable, so that molecules do not diffuse into the host polymer, then the average distance between particles must not significantly exceed the typical size of the target microbes if the microbe-inhibiting compound is to be effective. If the particles are much further apart than the typical size of a microbial cell, then these organisms can gain a foothold in the unprotected polymer regions between particles.
The sizes of microbes varies depending upon the general class (including genus and species) of the microbe. For example, bacteria are in the xcexcm range, fungi vary considerably in size and can be much larger than bacteria. Other microbes are, of course, considerably larger.
If the MI compound in particulate form is relatively unstable, then it is less important that the average distance between particles be smaller than the typical effective size of the target microbes. This is because the MI compound will diffuse into the inter-particle regions. The appropriate combination of parameters (e.g., particle size and inter-particle distance) for the dispersion are determined by
1. The appropriate minimum-inhibitory-concentration (xe2x80x9cMICxe2x80x9d);
2. The effective partial solubility of the MI compound in the host polymer; and
3. The diffusivity of the MI compound in the host polymer.
xe2x80x9cMICxe2x80x9d refers to the minimum concentration of a given agent that inhibits the growth of a particular microbe or a collection of different types of microbes. The MIC is typically determined by adding the MI compound at varying concentrations directly to growth medium into which the microbes are inoculated. The lowest concentration of the microbe-inhibiting compound at which the microbes are unable to grow (or which achieves a set amount of inhibition) is taken as the MIC.
The preferred MI compound, diiodomethyl-p-tolylsulphone or DIMTS (e.g., Ultrafresh UF-95(trademark)) is particularly effective as an antifungal or anti-algal agent. Its MIC is about 50 mg/L against Staphylococcus aureus bacteria;  greater than 1 g/L against Pseudomonas aeruginosa bacteria and about 5 mg/L against the fungus Aspergillus niger.
The MIC of triclosan (e.g., Irgasan(trademark) from Ciby-Geigy) has been measured as about 0.01 ppm against S. aureus; about 100 ppm for bacterium P aeruginosa; and about 100 ppm against A. niger.
Because MI agents tend to be more effective in solution than in a plastic, the MIC measured in solution can serve as a lower limit for the xe2x80x9cin-plasticxe2x80x9d or xe2x80x9csolid-phasexe2x80x9d MIC, which is an important measure for the present applications.
A first estimate of the solid phase MIC is generally taken to 10 times (or more) the measured solution-phase MIC. Provided there are no substantial deleterious effects, a multiple of even 100-1000-fold over the solution MIC is preferred.
The effective partial solubility is a measure of the tendency for an MI compound to detach or otherwise become dissociated from the particle in the polymer host. This solubility generally increases as the size of the particle decreases due to the fact that the chemical activity of a compound is greater when it comprises the concave region of a curved interface. The effect is described by the Kelvin equation, which, for the present purposes, can be expressed       RT              xe2x80x83                  ln                    (                  S                      S            o                          )              =      γ              xe2x80x83                  V                    (                              1                          R              1                                +                      1                          R              2                                      )
where S is the solubility of the microbe-inhibiting compound within the curved interface; So is the solubility of the microbe-inhibiting compound at an uncurved interface; R is the ideal gas constant; T is the temperature; xcex3 is the agent-host polymer interfacial energy; V is the specific volume of the particulate agent; and R1 and R2 are the principal radii of curvature of the interface between the microbe-inhibiting compound and the host polymer. It should be noted that protuberances or sharp edges (such as square or irregular shapes) typically possess local regions of very small radii R and thus, potentially much larger local solubility.
The effect of particulate size and shape on solubility can be used to tailor the properties. For example, small and/or irregular particulate size and shape will generally favor dissemination of the MI compound into the host polymer. The diffusivity of the agent in the host material determines that rate at which the microbe-inhibiting compound will spread into the host after detachment or dissociation from the particle. The effects of the effective solubility and the diffusivity are linked. The effective solubility determines the stable concentration of the MI compound just outside of the particulate region.
If the diffusivity is very small, then compound moves out from the particulate very slowly. The stable concentration can thus be maintained with very little concomitant transfer of compound from the particulate to the bulk of the host polymer (xe2x80x9cdiffusion-limitedxe2x80x9d case). If the diffusivity is large, then the microbe-inhibiting compound transferring from the particulate to the host polymer is rapidly moved away from the interface into the polymer bulk. In this case, the transfer of compound from particulate to host material occurs as fast as the agent can detach/ dissociate from the particulate (xe2x80x9cinterface-controlledxe2x80x9d case).
Diffusivity is also important for maintaining adequate concentration of the microbe-inhibiting compound ( greater than MIC) at the exterior surfaces of the final article. If the MI agent is depleted from, or otherwise becomes detached from, such surfaces, the diffusivity governs the rate at which it is replaced from the interior.
Information for determining preferred combinations of parameters can be obtained from simple experiments in which one incorporates the agent into the polymer and then observes the spatially variant properties within the polymer. For such diagnostic purposes, it is usually preferred to incorporate a deliberately low concentration of the microbe-inhibiting compound. For example, for a powdered agent with low solubility in a thermoplastic host polymer (so that it forms a particulate), and where the article of manufacture will be formed by injection molding, the following type of measurement can be performed:
1. Obtain the base polymer material in particulate form.
2. Cold mix the polymer particulates and the MI agent (e.g., shake in a closed container).
3. Heat and blend the mixture in an intensive hot mixer, the effective temperature of which meets the following criteria:
a. exceeds the melting temperature of the MI agent.
b. is below the degradation temperature of the MI agent.
c. is below the degradation temperature of the host polymer
d. is above the optimal processing temperature of the polymer
xe2x80x83Because of the heat which is often developed during the mixing process, it may be necessary to cool the mixer so that the material does not approach or exceed the degradation temperatures of the host polymer or of the MI agent.
4. After the mixing for the desired time, remove the material from the mixer.
5. View a piece in an optical microscope and attempt to identify the agent particulate.
6. If the particulate cannot be seen, section the plastic and view the sectioned surface. (For sectioning, it is often preferred first to freeze the polymer, e.g., cooling using liquid nitrogen or a dry-ice-ethanol solution. Subsequent fracture then typically yields clean, cross-sectional surfaces.)
7. If the particulate is not yet visible, use a higher-power microscope. If the particulate is still not visible, it may be necessary to use an electron microscope.
8. Record the typical sizes and inter-particle distances for a large number (e.g., 25) of the particulates. The average size is designated as d and the average inter-particle distance as {overscore ("xgr")}.
9. Inoculate the appropriate surface (e.g., exterior or cross-section) of a piece of the plastic using a pre-prepared culture of representative microbes. Keep the other pieces in a bag at room temperature.
10. Incubate the inoculated piece at 37xc2x0 C. for 24 hours (or whatever time is necessary for sufficient microbial growth).
11. Remove the sample from the incubator and examine under a microscope. One should see microbial growth punctuated by regions of less or no growth surrounding the particulates. The boundary of these regions corresponds to locations at which the (diffused) concentration of agent is approximately equal to the solid-phase MIC.
12. Measure and record the extent of these xe2x80x9czones of inhibition.xe2x80x9d The average extent of this zone-of-inhibition is designated xe2x80x9cx.xe2x80x9d
13. Repeat for the other samples of agent-incorporated material, where the storage time prior to inoculation (i.e., the time allowed for diffusion at room temperature) increases in a graded manner (e.g., 5, 10, 20 hrs.).
As an approximate (and phenomenological) measure of the diffusivity, D, can be described by the following expression:   D  ≈            x      2              2            t
where x is the measured (average) extent of the zone-of-inhibition at time, t. If desired, more numerically precise measures of the diffusivity can be obtained by parameter fitting to more physically precise diffusion models. See, e.g., Crank, The Mathematics of Diffusion, for presentation of such models.
Different combinations of host material-MI compound will require different intervals and conditions to obtain parameters. Through such routine experimentation, one can readily identify the desired intervals and conditions needed for obtaining the desired parameters.
Mixing can be improved by using an extruder. For example, the MI compound in powdered form and the host polymer can be fed into the hopper of an extruder, and the desired compounded plastic obtained at the exit die. Alternatively, pre-hot-mixed composites of host and compound can be fed into the extruder.
For adequate microbial protection of the plastic, it is preferred that the following condition be satisfied, at least approximately:             ξ      _                      2                D                          xe2x80x83                        τ               less than   1
where xcfx84 is the minimum interval between the forming and the use of the finished article. The MI compound which has diffused between the time of compounding and the time of molding is rendered more uniform during the molding process, resulting in a non-zero background concentration of the agent in the final article; this has the effect of lessening the apparent solid-phase MIC.
The primary variable to be controlled by processing in this type of system is {overscore ("xgr")}. For a particular given system, {overscore ("xgr")} is altered primarily by altering the quantity of the agent added, the original size and shape of the powder particles of the agent as added and the nature and parameters of the mixing process
The precise dependence of {overscore ("xgr")}, obtained empirically rather than theoretically, on the above factors can be complex. The magnitude of {overscore ("xgr")} is usually decreased by:
1) Increasing the quantity of the agent;
2) Decreasing the particle size of the agent before it is first mixed with the host polymer or the host polymer precursor (many methods are known in the art); and
3) Increasing the vigor (e.g., the magnitude of the shear rates, etc.) and/or the duration of the mixing/blending process.
The MI compound must be added to the polymer in a quantity which is effective for adequate inhibition of the growth of the target microbes. The minimum effective amount of the microbe-inhibiting compound is that amount which, if fully and homogeneously dissolved, would bring the total concentration up to the solid-phase MIC. If the agent forms an unstable particulate, then in practice, appreciably larger quantities should be added to the plastic. This is because a substantial amount of the microbe-inhibiting compound will remain in a particulate phase over the useful life of the article. Thus for an inter-particulate region to possess a concentration which exceeds the solid-phase MIC, the total amount added must, on average, exceed substantially the solid-phase MIC, the degree depending on the particle size, the effective solubility (which is affected by the particle size) and the diffusivity. Once the solid-phase MIC has been determined, however, additional levels to be added should exceed the solid-phase MIC by a factor of about 1.5-1000, preferably about 5-300. It is acceptable that the MIC compound be present in regions of the host polymer at concentrations less than the solid-phase MIC provided that such regions are smaller than the microbes of interest.
If the microbe-inhibiting compound dissolves substantially or fully in the polymer, then the effective MI compound concentration must exceed the solid-phase MIC less dramatically than in the particulate case above. The concentration typically varies from the solid-phase MIC to about 20 times higher, preferably from about 2 to about 10 times the solid phase MIC.
It should be noted that during use, the MI agent frequently is lost from, or otherwise rendered inactive on, the surfaces of the finished article. This occurs by dissolution into, or otherwise adherence to, other bodies which contact the finished article. It can also occur as a result of the tendency of the MI agent to degrade with time, either alone or via interaction with microbes. It is therefore preferred to incorporate larger amounts of the MI compound than would be necessary for inhibition of microbial proliferation early in the lifetime of the finished article. The preferred degree of such overload to account for these processes typically increases with the surface-to-volume ratio of the finished article, the vigor with which the article is used, the degree of adhesion of the MI agent to the surface of the article, and with the tendency of the MI agent to become xe2x80x9cde-activatedxe2x80x9d at the surface. A typical range for this overloading is about 10-200%, preferably about 30-80%. Such overloading is not considered to be a problem because (a) the preferred MI compounds are typically quite inexpensive at the concentrations employed, (b) preferred MI agents are frequently sufficiently non-toxic, and (c) their effects on other properties of the final polymer are often negligible at the concentrations necessary for adequate microbial protection.
In those cases where it is difficult to disperse the MI compound in the polymer, it is often preferred to incorporate the MI agent into a carrier in which the microbe-inhibiting compound is more readily dispersed. This carrier material or resin can then be blended with the primary host polymer by methods known in the art of compounding polymers for molding or extrusion. For example, U.S. Pat. No. 4,789,692, which is hereby incorporated by reference, describes methods for compounding solid resins containing high concentrations of biocides. These resins are intended to be blended with other base-polymer resins to result in a final polymer with increased compatibility with the MI compound.
Because degradable polymers often comprise a blend of polymeric materials, one can choose the optimum carrier for the group of constituent materials. For example, starch-based biodegradable polymers often comprise starch blended (reacted or non reacted) with polymers such as polyethylene. The MI agent can first be incorporated in the starch or in the polyethylene (or other polymer) raw materials prior to their mixing.
A variety of dispersion aids can be used to assist in the dispersion of particulate or powder additives in the polymers. These generally contain at least one functional group with affinity for the particulate or powder. If the affinity is particularly strong (e.g., forms a covalent bond), the aid is referred to as a xe2x80x9ccoupling agent.xe2x80x9d
If the MI agent is in liquid form (or if it can be readily transformed to, dispersed in, or dissolved in a liquid carrier), it is often preferred to incorporate a surfactant or dispersing agent directly into the liquid. The so-treated MI agent should then be more readily dispersed in the host polymer. Dispersing agents can also be used with solid phase MI agents.
Furthermore, the hydrophilic properties of some degradable materials contribute to their tendency to degrade. Such materials typically are at least partially soluble in water so that the process of degradation is hastened in a humid or wet environment. To arrest or slow further unwanted degradation, a surfactant or other surface-energy-lowering additive, well-known in the art, is incorporated into the MI compound-containing hydrophilic polymer.
It may be desired to impart MI properties to a polymer blend which contains two or more different polymeric materials which are not intermixed at a molecular level, i.e., a phase-separated polymer. In such a case, the effective solubility is likely to vary from phase to phase. Thus, the MI compound can be particulate in one phase and fully dissolved in another. Its concentration in the 2 or more phases may vary. The microbe-inhibiting compound""s concentration in one place can exceed the solid phase MIC while in a second phase it does not. This may be a problem only if the typical spatial extent of the phase having a sub-MIC concentration is appreciably greater than the typical size of the microbes of interest. If so, then one must increase the MI agent concentration in this phase. This is preferably achieved by increasing the overall loading level. An alternative method is to add a surfactant or other compatibilizing agent to the polymer composition.
Highly porous biodegradable materials are particularly benefitted from the inclusion of MI compounds as disclosed herein. Their high internal surface areas promote water sorption and/or condensation, which in turn enhance susceptibility to invasion and growth of microbes, especially fungi. The incorporation of an effective amount of a MI compound, preferably one that is most efficacious fungi, into the host polymer material prior to foaming, is preferred. For proper foaming, the polymer melt must be sufficiently fluid prior to the actual foaming step. One must therefore select an MI compound or a master batch/MI compound combination that does not adversely affect the rheological properties of the polymer melt under the conditions in which the melt is maintained just prior to foaming and during the foaming process.
It may be desired to use more than one type of MI agent, e.g., in multi-phase polymers where one or more of the phases tends to expel the MI agent. It is more commonly desired, however, because of the synergistic quality of MI agent xe2x80x9ccocktailsxe2x80x9d (which again, are included in the term MI xe2x80x9cagentxe2x80x9d or xe2x80x9ccompoundxe2x80x9d). For example, U.S. Pat. No. 5,772,640, hereby incorporated by reference, discloses incorporation of a synergistic combination of triclosan and chlorhexidine in the fabrication of polymeric medical articles.
It may be desired to use MI agent cocktails comprising several xe2x80x9cnarrow bandxe2x80x9d or highly-specific agents to xe2x80x9cprogramxe2x80x9d a highly specific inhibition spectrum into the polymer. The ability to program such specific inhibition spectra can be useful for a variety of diagnostic devices. For example, one can incorporate a spatially variant inhibition spectra on a plastic sheet. An unknown microbial culture can then be spread on the sheet, and, after a suitable incubation, information regarding the microbial identity can be derived from the emerging spatial pattern.
As will be understood from the foregoing description, the amount of MI agent in the polymer mixture will vary over a wide range, depending on the MI agent, the polymer blend and the factors identified above. However, the amount of MI agent in the polymer blend will generally vary from 0.001% to 3%, preferably between 0.005% and 1% (by weight).
As mentioned earlier, it is important to ensure during processing or compounding that the degradation temperature of the MI agent is not exceeded. Because incorporation of the agent may lower the degradation temperature of the agent and/or of the host polymer, it is preferred, in the absence of specific information regarding the degradation of the composite material, to perform all processing and compounding substantially below the individual degradation temperatures. It is preferred to verify (e.g., by thermal and/or other methods known in the art) that the temperatures used have not exceeded actual composite degradation temperatures.
Although the invention has been described with respect to degradable plastics in which are incorporated agents to counteract in a controllable manner the natural susceptibility which these plastics have to harbor microbes and for microbially-enhanced degradation processes, the invention also relates to plastics which would not generally be described as degradable or as having a significant degradable component.
Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present invention, unless specified.

Degradable plastics possessing a microbe-inhibiting quality


A new and distinct Hosta plant named ‘Mini Skirt’ with coarsely-sinuate cordate leaf blades having variegation of creamy yellow to creamy white margins and dark green center and feathering intermediate colors. The plant habit is short, compact and rounded with flowering just above foliage, and the leaves and scapes are thick substance and stiff.

The present invention relates to a new and distinct Hosta plant, Hosta 'Mini Skirt' hereinafter also referred to as the new plant or just the cultivar name, 'Mini Skirt'. Hosta 'Mini Skirt' was discovered by Maria Martinez as a non-induced, naturally-occurring, whole-plant mutation in a batch of tissue cultured Hosta 'Mighty Mouse' (not patented) at a nursery greenhouse in Zeeland, Mich., USA during the summer of 2008. The new plant has been asexually propagated by division at the same nursery in Zeeland, Mich. USA since 2009 and also by careful shoot tip plant tissue culture with the resultant asexually propagated plants having retained all the same traits as the original plant. 'Mini Skirt' is stable and reproduces true to type in successive generations of asexual reproduction.
Hosta 'Mini Skirt' has not been made publically available or sold anywhere in the world prior to the filing of this application. Any public disclosure of 'Mini Skirt' has been by the inventor, or one who obtained the material either directly or indirectly from the inventor, and any such disclosure has not been made more than one year prior to the application of this invention.
There are over 4,500 registered Hostas with The American Hosta Society, which is the International Cultivar Registration Authority for the genus Hosta. Hosta 'Mini Skirt' is a sport from 'Mighty Mouse' (not patented) which is one of many sports from Hosta 'Blue Mouse Ears' (not patented). The most similar Hosta cultivar known to the applicant is Hosta 'Mighty Mouse'. The new plant differs from 'Mighty Mouse' in that the margin appears wider but most notably in the course wave in the leaf bland, whereas 'Mighty Mouse' has a flat leaf blade. Another cultivar, 'Ruffled Mouse Ears' (not patented), has similar sport history, both originally arising from 'Blue Mouse Ears'. 'Ruffled Mouse Ears' has a similar coarse wave to the leaves but is not variegated. Hosta 'Pure Heart' (not patented) is a sport of 'Blue Mouse Ears' with foliage having a white center and green margin, but 'Pure Heart' also has a flatter leave than 'Mini Skirt' and variegation in a reverse pattern. Hosta 'Mouse Tracks' (not patented) is another sport of 'Blue Mouse Ears' with creamy streaking variegation throughout the dark green foliage and without a wide creamy white to creamy yellow margin. Hosta 'Mouse Tracks' also has a flatter leaf than 'Mini Skirt'.
Other Hosta cultivars have short habit and variegation of a similar nature, or other individual traits similar to 'Mini Skirt' but the new plant differs from the above cultivars and all other Hostas known to the applicant, by the combination of the following traits.                1. Coarsely-sinuate cordate leaf blades.        2. Leaves with creamy yellow to creamy white margins and dark green center and feathering intermediate colors.        3. Short, compact, rounded habit with flowering just above foliage.        4. Stiff scapes and leaves with thick substance.


A method is disclosed for preserving entered data in an electronic document from being obliterated with additional data. A code address or flag is assigned to each electronic document. The code address identifies the electronic document as modifiable or non-modifiable. If the electronic document is modifiable, entered data may be obliterated or destroyed by entering additional data thereover. If the code address identifies the electronic data as non-modifiable, the entered data is preserved by preventing additional data to be entered which will obliterate the previously entered data. The entered data becomes annotations to the electronic document having a non-destructible format, i.e., color and masking, allowing an operator to freely add additional data without destroying the entered data.

1. Field of the Invention
The invention relates to a method for preserving data in an electronic document. More particularly, the invention relates to a method for preserving data in an electronic document while annotating the electronic document.
2. Description of the Related Art
Modifying electronic documents, i.e., documents of data stored in electronic form, enables operators of such systems to reduce their dependency on paper. Modifying documents electronically does, however, present a special problem in environments requiring the preservation of the data input into the electronic document, regardless of the timeliness or relevance of the data currently in the electronic document. More specifically, data having historical significance with respect to the event or events being recorded should not be destroyed. Protection of this information is required in environments such as doctors offices, dentists offices, and the like where it is critical for historical information never to be obliterated.
U.S. Pat. No. 5,347,579, issued to Blandford, discloses a method for generating a personal diary using a computer system. The system receives all entries, coupled with a code. The code identifies which of those entries must be maintained and which of those entries may be "torn out" or removed from the electronic diary. The system, however, requires the existence of two versions for each data block; one which is time-stamped and stored forever, and another which is a working block capable of being edited. Storing data twice is a cumbersome, time consuming, memory consuming protocol.
Pen-based computer systems add another dimension to the loss of data problem because, unlike text and text form inputs typical of most software applications, data can be entered by a stroke of a pen. Each stroke can potentially obliterate data previously entered and considered important to save. Therefore, there is a need in the art for a system which allows a pen-based computer system to function similar to its traditional ink pen/paper counterpart without losing important, historical data regardless of the intent of preservation.

Method for preserving data in an electronic document


A cap assembly for a gas chromatography injection port includes a two-piece septum. The two-piece septum includes a syringe seal for sealing an injection needle and a duckbill seal for sealing the injection port when the needle is not inserted. The syringe seal includes three annular ribs in its aperture. At the aperture base is a sealing rib that provides the main sealing function for the syringe seal. Just above the sealing rib is a stress-relief rib. At the top of the aperture is a wiping rib. The wiping rib wipes dust on the needle exterior so that it does not enter the aperture. Dust entering the aperture can be retained in the relatively large dust pocket between the wiping rib and the strain-relief rib. The septum is held in place by a septum nut that has a recess above the wiping rib for holding dust removed from the needle by the wiping rib. A washer in the recess prevents the syringe seal from deforming into the recess. The septum nut includes a guide aperture section that aligns the syringe needle with the apertures of the syringe seal and the duckbill seal. The septum nut is made of anodized aluminum to provide ready machinability for formation of the guide aperture section and sufficient hardness to resist damage inflicted by the syringe needle.

The present invention relates to chromatography systems used for chemical analysis and, more particularly, to an improved septum for an injection port of a gas chromatography system.
In gas chromatography, samples are separated into their components by passing the sample through a separating column. The sample is introduced into a flowing carrier gas in an injection port. The carrier gas sweeps the sample from the injection port into the separating column. The separated components emerging from the column are eluted through a detector that monitors the elution over time. A chromatogram, representing eluting quantity as a function of time, is generated by plotting the detector output signal.
Typically, the carrier gas is sealed from the outside world by a rubber septum. The sample is introduced into the injection port using a syringe that pierces the septum. The sample is injected into the inlet system and the syringe needle is withdrawn.
The septum must serve two functions. First, it must form a seal around the needle to prevent leaks while the injection is effected. Second, it must reseal the injection port after the syringe needle has been withdrawn and maintain this seal while the chromatographic separation is being executed. A leak occurring while the needle is in the septum can cause part of the injected sample to escape the injection system. This "injection" leak is difficult to detect because it occurs during the dynamic process of injection and is only apparent by careful examination of the quantitative results of the chromatogram. A failure to seal after the needle is withdrawn is more easily detected. The resulting "post-injection" leak is evident from variations in the characteristic retention time for a chromatographic peak resulting from variations in the column flow rate. Some capillary column injection ports may show different behavior for a post-injection leak because of their flow configuration.
Septum deterioration and resulting failure are serious problems. Monitoring a system for leaks can be costly and time consuming. Replacement of seals is inconvenient. Problems of detection and replacement are aggravated in automated systems which may run unattended for as many as 100 samples. A failure early in a run can impair the validity of the results for all subsequent samples.
Septum deterioration is inevitable due to the action of the syringe needles used for injection. Syringe needles must be strong enough to pierce the septa of sample containers and injection ports without bending or buckling. This strength requirement leads to the use of larger diameter needles. Larger diameter needles require greater insertion force to pierce a septum, which is thus subject to greater wear. The larger needles also make larger holes or tears in the septum, which are harder to reseal after needle withdrawal. Needles of smaller diameter cause less damage to the septum and make resealing easier, but are much more susceptible to bending when piercing a seal.
Syringe needles are made with sharp, beveled points to slice through the septa with lower force. However, the slicing action of repeated injections with beveled needles can lacerate a septum, which then begins to leak. In addition, small pieces of rubber torn from a septum by the needles can fall into the injection port liner. Once in the liner, these pieces can affect the analysis in two ways. First, they can release compounds which can appear as "ghost peaks" in the chromatogram. Second, they can adsorb or partition sample components as they pass through the injection port, causing distortion of peak shapes in the chromatogram. In either case, the validity of the resulting chromatogram is impaired.
Taking into account these considerations, most gas chromatographs use a rubber septum, approximately 3 mm thick and 6-12 mm in diameter. Syringes typically used with such septa are 10 microliter total capacity, with a sharp beveled 26 gauge, i.e., 0.48 mm diameter, needle. These are used for both manual injection and for automatic liquid samplers. Alternatively, thicker "cylindrical" septa are used to improve the reliability of sealing after multiple injections. These have the disadvantage of requiring higher syringe force.
Especially strenuous demands are made on a septum in automatic liquid samplers, such as the Hewlett-Packard 7673. This sampler uses a very rapid injection cycle. A differently shaped needle is adapted so that it can pierce a septum, the liquid sample can be injected into the injection port liner, and the needle can be removed from the port in less than 0.25 second before the syringe needle contents can be heated significantly by the injection port or the septum. The needle has a relatively large diameter, e.g., 0.66 mm, to allow it to withstand the higher force required to pierce the septum at high speed without bending or buckling. The needle has a blunt tip which facilitates a properly directed spray pattern for the sample. The larger diameter and blunt tip cause greater damage to the septum per injection, thus shortening the septum life before leaks occur or pieces of septum fall into the injection liner.
The problem of laceration can be addressed by using a septum having a predefined path for needle penetration. For example, septa have been adapted from "duckbill" seals. A duckbill seal comprises a flat rubber tube with two flat surfaces which can seal against each other. Duckbill seals are often used as check valves in flow systems because they open with very low pressure drop in one direction while sealing in the other direction. Duckbill seals are effective under high pressure, which causes the flat surfaces to press against each other more tightly.
Because a slit is preformed between the flat surfaces, a blunt needle can be inserted with low force through a duckbill seal many times without tearing or crumbling the rubber by forcing the flat surfaces apart. However, the flat seals do not form an effective seal about a syringe needle so leaks can occur during injection. In addition, the low pressure drops across the seal can be insufficient to close the flat surfaces, allowing post-injection leaks. The problem with post-injection leaks can be remedied by adding a spring to force the sealing surfaces together.
A duckbill seal has been included in a inlet assembly for a capillary column. For example, in the "Hewlett-Packard 1988 Analytical Supplies Catalog and Chromatography Reference Guide", page 35, a "Cool On-Column Inlet" includes a duckbill seal. Inspection of the actual system reveals that a stainless steel probe is used to separate the duckbill surfaces. Once the surfaces are separated by the probe, the needle is extended through the probe and the probe is withdrawn so that the duckbill closes around the needle. Neither the probe nor the duckbill seals the needle completely, so that some leakage generally occurs. It is noted that the inner perimeter of the duckbill seal is about 1.6 mm at the duckbill end and about 3.1 mm at the end where the needle is first inserted, so that this latter end never forms a seal with the needle.
A septum including interlocked syringe and duckbill seals is disclosed in U.S. Pat. No. 4,954,149 to Fullemann. The annular syringe seal prevents leakage during injection by syringe. The duckbill seal prevents fluid leakage after the needle is withdrawn from the septum. A spring clip is used to urge the duckbill closed as the needle is withdrawn to ensure closure even at low pressures. The syringe seal aperture is wider at the top to help guide the needle. This aperture converges to an annular base sealing element, the diameter of which is smaller than the needle to provide a tight seal while the needle is inserted. While a definite improvement over the simple duckbill seal, this hybrid-seal injection septum could leak due to deformation of the base sealing detail of the syringe seal when the needle was misaligned.
An improved interlocked injection septum uses dual annular sealing elements in the syringe seal. An annular sealing element is located at the base of the syringe seal, while an annular strain-relief element is located just above the sealing element. A misaligned needle deforms the guide detail. The deforming force, however, moves the sealing element into alignment with the needle. Thus, the sealing element is not deformed and so is able to form a secure seal against the needle.
This improved interlocked injection septum essentially answered the industry call for a reliable and longer lasting seal. However, once the original objectives were met, the industry raised its sights. After thousands of injections, the dual-detail interlocked injection septa are prone to leakage. What is needed is a similarly effective septum that has a substantially greater mean-time-before-failure (MTBF).


An aqueous conditioning shampoo composition comprising, in addition to water:

This invention relates to shampoo compositions, and more particularly to shampoo compositions containing emulsified particles of silicone, which compositions condition the hair leaving it softer and more manageable.
The use of silicones as conditioning agents in cosmetic formulations is well known and widely documented in the patent literature. Generally, dispersed droplets of the silicone oil are suspended in the composition, which is then applied to the hair to deposit the silicone material on the hair shaft.
A typical method of silicone shampoo manufacture is disclosed in WO 92/10162. Essentially, the silicone material is emulsified directly into the shampoo by an in situ hot process, in which the complete shampoo mixture incorporating the silicone is mixed thoroughly at elevated temperature, pumped through a high shear mill and then cooled. The silicone can be dispersed in a first process stage with anionic surfactant and fatty alcohol to form a premix. The premix is then mixed with the remaining materials of the shampoo, pumped through a high shear mill, and cooled to obtain the final composition.
A disadvantage associated with an in situ hot process such as is described in WO 92/10162 is that factory handling of viscous silicone oil is difficult in the context of a full shampoo manufacturing operation.
A further disadvantage is that special equipment is normally needed to control silicone particle size during manufacture. GB 2 170 216 A discloses a similar process, in which the full shampoo composition incorporating insoluble, non-volatile silicone is sheared with a high shear mixer until the silicone particles are on average less than 2 microns in diameter. The particle size distribution is then said to be from about 2 to about 55 microns.
In order to solve the above mentioned problems with in situ hot processing of silicone, the alternative of incorporating the silicone as a preformed aqueous emulsion has been proposed. Such a method has the consequences that the silicone is incorporated with a predeterminable, controllable particle size distribution. The silicone is insoluble and remains emulsified in the fully formulated shampoo composition, and thus the step of high shear processing of the silicone within the fully formulated shampoo composition is not required. This also makes manufacture of the compositions easier.
A typical method for incorporating insoluble, non-volatile silicone materials into a conditioning shampoo is disclosed in U.S. Pat. No. 5,085,857 in which such materials are incorporated in the shampoo composition as a pre-formed aqueous emulsion of average particle size less than 2 microns. All the ingredients are mixed in a simple hot or cold process in which the average particle size of the silicone material in the emulsion remains the same in the final shampoo composition. Preferably, this size is from 0.01 to 1 micron, e.g. 0.4 micron.
EP 0 529 883 A1 discloses hair shampoo compositions made by an equivalent method and comprising microemulsified particles of silicone having a particle size of 0.15 microns or less, e.g., 0.036 microns. Reducing the silicone particle size still further in this way is said to improve stability, optical properties and conditioning performance.
The shampoos of U.S. Pat. No. 5,085,087 and EP 0 529 883 A1 require the presence of a cationic polymer to deposit the silicone efficiently from the formulation onto the hair. A problem encountered with these small particle size silicone/cationic polymer formulations is that they can give an undesirable sensory feel, typically manifest as a perception of xe2x80x9cslippinessxe2x80x9d and/or heaviness on dry hair.
We have now found that the utilisation of insoluble, non-volatile silicone, in the form of an aqueous, preformed emulsion of large particle size in a surfactant-based shampoo composition will impart conditioning benefit to the hair without the dry hair sensory negatives associated with the prior art compositions discussed above.
Surprisingly and advantageously, we have found that in compositions of our invention, the presence of cationic polymer selectively enhances the wet properties of the shampoo, e.g., wet feel and ease of wet combxe2x80x94whilst reducing the ease of dry combing. In contrast, we found that the presence of cationic polymer in prior art formulations incorporating cationic polymer and smaller particle size pre-formed silicone emulsions did not give a selective increase in ease of wet combing. Ease of dry combing was increased to at least the same extent.
The selective enhancement of wet properties such as ease of wet combing observed with compositions of the present invention is of benefit to the consumer. This is because consumers need to detangle their hair easily when wet, but when it is dry, if the hair slips through the comb too easily then it can be difficult to put into style.
The invention provides an aqueous shampoo composition comprising, in addition to water:
i) at least one surfactant chosen from anionic, nonionic, zwitterionic or amphoteric surfactants or mixtures thereof;
ii) emulsified particles of an insoluble, nonvolatile silicone;
iii)a cationic hair conditioning polymer having a cationic charge density of about +3.0 meq/gram or less,
in which the emulsified particles of insoluble, non-volatile silicone are incorporated into the shampoo composition as a preformed aqueous emulsion having an average silicone particle size in the emulsion and in the shampoo composition of from 2 to 30 microns.
In another aspect, the invention provides a method of making such a shampoo composition, by mixing together water, the surfactant, the cationic conditioning polymer and a preformed aqueous emulsion of the silicone, wherein the silicone in the emulsion and in the shampoo composition has an average particle size of from 2 to 30 microns.
i) Surfactant
The composition according to the invention comprises a surfactant chosen from anionic, nonionic, zwitterionic or amphoteric surfactants or mixtures thereof.
Suitable anionic surfactants include the alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates, N-alkoyl sarcosinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates, and alpha-olefin sulphonates, especially their sodium, magnesium ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups generally contain from 8 to 18 carbon atoms and may be unsaturated. The alkyl ether sulphates, alkyl ether phosphates and alkyl ether carboxylates may contain from one to 10 ethylene oxide or propylene oxide units per molecule, and preferably contain 2 to 3 ethylene oxide units per molecule.
Examples of suitable anionic surfactancs include sodium oleyl succinate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, sodium dodecylbenzene sulphonate, triethanolamine dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauroyl isethionate and sodium N-lauryl sarcosinate. The most preferred anionic surfactants are sodium lauryl sulphate, triethanolamine lauryl sulphate, triethanolamine monolauryl phosphate, sodium lauryl ether sulphate 1EO, 2EO and 3EO, ammonium lauryl sulphate and ammonium lauryl ether sulphate 1EO, 2EO and 3EO.
Nonionic surfactants suitable for use in compositions of the invention may include condensation products of aliphatic (C8-C18) primary or secondary linear or branched chain alcohols or phenols with alkylene oxides, usually ethylene oxide and generally having from 6 to 30 ethylene oxide groups. Other suitable nonionics include mono- or di-alkyl alkanolamides. Example include coco mono- or di-ethanolamide and coco mono-isopropanolamide.
Amphoteric and zwitterionic surfactants suitable for use in compositions of the invention may include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines), alkyl glycinates, alkyl carboxyglycinates, alkyl amphopropionates, alkylamphoglycinates alkyl amidopropyl hydroxysultaines, acyl taurates and acyl glutamates, wherein the alkyl and acyl groups have from 8 to 19 carbon atoms. Examples include lauryl amine oxide, cocodimethyl sulphopropyl betaine and preferably lauryl betaine, cocamidopropyl betaine and sodium cocamchopropionate.
The surfactants are present in shampoo compositions o. the invention in an amount of from 0.1 to 50% by weight, preferably from 0.5 to 30% by weight.
Generally, the surfactants are present in shampoo compositions of the invention in an amount of from 0.1 to 50%, preferably from 5 to 30%, more preferably from 10% to 25% by weight.
ii) Silicone
The shampoo composition of the invention also comprises an insoluble, non-volatile silicone, which may be one or more polyalkyl siloxanes, one or more polyalkylaryl siloxanes, or mixtures thereof. The silicone is insoluble in the aqueous matrix of the composition and so is present in an emulsified form, with the silicone present as dispersed particles.
Suitable polyalkyl siloxanes include polydimethyl siloxanes which have the CAFTAN designation dimethicone, having a viscosity of from 5 to 100,000 centistokes at 25xc2x0 C. These siloxanes are available commercially from the General Electric Company as the Viscasil series and from Dow Corning as the DC 200 series. The viscosity can be measured by means of a glass capillary viscometer as set out further in Doe Corning Corporate Test Method CTM004 Jul. 20, 1970.
Also suitable is polydiethyl siloxane.
The polyalkylaryl siloxanes which may be used in the compositions of the invention include polymethylphenyl polysiloxanes having a viscosity of from 15 to 65 centistokes at 25xc2x0 C. The siloxanes are available commercially from the General Electric Company as SF1075 methyl phenyl fluid or from Dow Corning as 556 Cosmetic Grade Fluid.
Also suitable are silicone gums, such as those described in U.S. Pat. No. 4,152,416 (Spitzer), and on General Electric Silicone Rubber product Data Sheet SE 30, SE 33, SE 54 and SE 76. xe2x80x9cSilicone gumsxe2x80x9d denotes polydiorganosiloxanes having a molecular weight of from 200,000 to 1,000,000 and specific examples include polydimethyl siloxane polymers, polydimethyl siloxane/diphenyl/methylvinylsiloxane copolymers, polydimethylsiloxane/methylvinylsiloxane copolymers and mixtures thereof.
Aminofunctional silicones which have the CTFA designation amodimethicone, are also suitable for use in the compositions of the invention, as are polydimethyl siloxanes having hydroxyl end groups (which have the CTFA designation dimethiconol).
The silicone materials described above are incorporated in the shampoo composition of the invention as a pre-formed aqueous emulsion. The average particle size of the silicone material in this emulsion and in the shampoo composition is from 2 to 30 microns, preferably from 2 to 20 microns, more preferably 3 to 10 microns. Particle size may be measured by means of a laser light scattering technique, using a 2600D Particle Sizer from Malvern Instruments.
The pre-formed emulsion may be prepared by high shear mechanical mixing of the silicone and water, or by emulsifying the insoluble, non-volatile silicone with water and an emulsifierxe2x80x94mixing the silicone into a heated solution of the emulsifier for instance, or by a combination of mechanical and chemical emulsification. A further suitable technique for preparation of the emulsions is emulsion polymerisation. Emulsion polymerised silicones as such are described in U.S. Pat. No. 2,891,920 (Hyde), U.S. Pat. No. 3,294,725 (Findlay) and U.S. Pat. No. 3,360,491 (Axon).
Any surfactant materials either alone or in admixture may be used as emulsifiers in the preparation of the pre-formed silicone emulsions. Suitable emulsifiers include anionic, cationic and nonionic emulsifiers. Examples of anionic emulsifiers are alkylarylsulphonates, e.g., sodium dodecylbenzene sulphonate, alkyl sulphates e.g., sodium, lauryl sulphate, alkyl ether sulphates, e.g., sodium lauryl ether sulphate nEO, where n is from 1 to 20 alkylphenol ether sulphates, e.g., octylphenol ether sulphate nEO where n is from 1 to 20, and sulphosuccinates, e.g., sodium dioctylsulphosuccinate.
Examples of nonionic emulsifiers are alkylphenol ethoxylates, e.g., nonylphenol ethoxylate nEO, where n is from 1 to 50, alcohol ethoxylates, e.g., lauryl alcohol nEO, where n is from 1 to 50, ester ethoxylates, e.g., polyoxyethylene monostearate where the number of oxyethylene units is from 1 to 30.
Typically, a pre-formed emulsion will contain around 50% of silicone. Pre-formed emulsions are available from suppliers of silicone oils such as Dow Corning, General Electric, Union Carbide, Wacker Chemie, Shin Etsu, Toshiba, Toyo Beauty Co, and Toray Silicone Co. Examples are the material sold as DC-1310 by Dow Corning, and the materials sold as X-52-1086, X-52-2127 and X-52-2112 by Shin-Etsu.
The compositions of the invention typically contain from 0.01 to 20% by weight, preferably from 0.1 to 10%, more preferably from 0.25 to 3% by weight of insoluble, non-volatile silicone. If less than 0.01% by weight is present in the composition, little conditioning benefit is observed, and if more than 20% by weight is present, the hair will appear greasy.
The aqueous pre-formed emulsion may be incorporated into the shampoo composition in an amount of from 0.02 to 40% by weight, preferably from 0.2 to 20% by weight.
The exact quantity of emulsion will of course depend on the concentration of the emulsion, and should be selected to give the desired quantity of insoluble, non-volatile silicone, in the final composition.
iii) Cationic Conditioning Polymer
A further component of hair treatment compositions of the invention is a cationic conditioning polymer.
The polymer may be a homopolymer or be formed from two or more types of monomers. The molecular weight of the polymer will generally be between 5,000 and 10,000,000, typically at least 10,000 and preferably in the range 100,000 to about 2,000,000. The polymers will have cationic nitrogen containing groups such as quaternary ammonium or protonated amino groups, or a mixture thereof.
The cationic charge density is suitably at least 0.1 meq/g, preferably above 0.8 or higher. The cationic charge density should not exceed 3 meq/g. It is preferably less than 2 meq/g. The charge density can be measured using the Kjeldahl method and should be within the above limits at the desired pH of use, which will in general be from about 3 to 9 and preferably between 4 and 8.
The cationic nitrogen-containing group will generally be present as a substituent on a fraction of the total monomer units of the cationic conditioning polymer. Thus when the polymer is not a homopolymer it can contain spacer non-cationic monomer units. Such polymers are described in the CTFA Cosmetic Ingredient Directory, 3rd edition.
Suitable cationic conditioning polymers include, for example, copolymers of vinyl monomers having cationic amine or quaternary ammonium functionalities with water soluble spacer monomers such as (meth)acrylamide, alkyl and dialkyl (meth)acrylamides, alkyl (meth)acrylate, vinyl caprolactone and vinyl pyrrolidine. The alkyl and dialkyl substituted monomers preferably have C1-C7 alkyl groups, more preferably C1-3 alkyl groups. Other suitable spacers include vinyl esters, vinyl alcohol, maleic anhydride, propylene glycol and ethylene glycol.
The cationic amines can be primary, secondary or tertiary amines, depending upon the particular species and the pH of the composition. In general secondary and tertiary amines, especially tertiary, are preferred.
Amine substituted vinyl monomers and amines can be poly-merized in the amine form and then converted to ammonium by cuaternization.
Suitable cationic amino and quaternary ammonium monomers include, for example, vinyl compounds substituted with dialkyl amincalkyl acrylate, dialkylamino alkylmethacrylate, monoalkylaminoalkyl acrylate, monoalkylaminoalkyl methacrylate, trialkyl methacryloxyalkyl ammonium salt, trialkyl acryloxyalkyl ammonium salt, diallyl quaternary ammonium salts, and vinyl quaternary ammonium monomers having cyclic cationic nitrogen-containing rings such as pyridinium, imidazolium, and quaternized pyrrolidine, e.g., alkyl vinyl imidazolium, and quaternized pyrrolidine, e.g., alkyl vinyl imidazolium, alkyl vinyl pyridinium, alkyl vinyl pyrrolidine salts. The alkyl portions of these monomers are preferably lower alkyls such as the C1-C3 alkyls, more preferably C1 and C2 alkyls.
Suitable amine-substituted vinyl monomers include dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide, and dialkylaminoalkyl methacrylamide, wherein the alkyl groups are preferably C1-C7 hydrocarbyls, more preferably C1-C3, alkyls.
The cationic conditioning polymers can comprise mixtures of monomer units derived from amine- and/or quaternary ammonium-substituted monomer and/or compatible spacer monomers.
Suitable cationic conditioning polymers include, for example: copolymers of 1-vinyl-2-pyrrolidine and 1-vinyl-3-methyl-imidazolium salt (e.g., Chloride salt) (referred to in the industry by the Cosmetic, Toiletry, and Fragrance Association, xe2x80x9cCTFAxe2x80x9d. as Polyquaternium-16) such as those commercially available from BASF Tyandotte Corn. (Parsippany, N.J., USA) under the LUVIQUAt tradename (e.g., LUVIQUAT FC 370); copolymers of 1-vinyl-2-pyrrolidine and dimethylaminoethyl methacrylate (referred to in the industry by CTFA as Polyquaternium-11) such as those commercially from Gar Corporation (Wayne, N.J., USA) under the GAFQUAT tradename (e.g., GAFQUAT 755N); cationic diallyl quaternary ammonium-containing polymer including, for example, dimethyldiallyammonium chloride homopolymer and copolymers of acrylamide and dimethyldiallyammonium chloride, referred to in the industry (CTFA) as Polyquaternium 6 and Polyquaternium 7, respectively; mineral acid salts of amino-alkyl esters of homo-and co-polymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms, as described in U.S. Pat. No. 4,009,256; and cationic polyacrylamides as described in our copending UK Application No. 9403156.4 (WO95/22311)
Other cationic conditioning polymers that can be used include polysaccharide polymers, such as cationic cellulose derivatives and cationic starch derivatives.
Cationic polysaccharide polymer materials suitable for use in compositions of the invention include those of the formula:
wherein: A is an anhydroglucose residual group, such as starch or cellulose anhydroglucose residual,
R is an alkylene axyalklene, polyoxyalkylene, or hydroxyalkylene group, or combination thereof, R1, R2 and R3 independently are alkyl, aryl, alkylaryl, arylalkyl, alkoxyalkyl, or alkoxyaryl groups, each group containing up to about 18 carbon atoms, and the total number of carbon atoms for each cationic moiety (i.e., the sum of carbon atoms in R1, R2 and R3) preferably being about 20 or less, and X is an anionic counterion , as previously described.
Cationic cellulose is available from Amerchol Corp. (Edison, N.J., USA) in their Polymer JR (trade mark) and LR (trade mark) series of polymers, as salts of hydroxyethyl cellulose reacted with trimethyl ammonium substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 10 Another type of cationic cellulose includes the polymeric quaternary ammonium salts of hydroxyethyl cellulose reacted with lauryl dimethyl ammonium-substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 24. These materials are available from Amerchol Corp. (Edison, N.J., USA) under the tradename Polymer LM-200.
Other cationic conditioning polymers that can be used include cationic guar gum derivatives, such as guar hydroxypropyltrimonium chloride (Commercially available from Celanese Corp. in their Jaguar trademark series). Other materials include quaternary nitrogen-containing cellulose ethers (e.g., as described in U.S. Pat. No. 3,962,418), and copolymers of etherified cellulose and starch (e.g., as described in U.S. Pat. No. 3,958,581.
Preferably the cationic conditioning polymer is selected from the group comprising cationic polyacrylamides, hydroxyalkyl cellulose ethers and cationic guar derivatives. Particularly preferred are Jaguar C13S with a cationic charge density of 0.8 meq/g. Jaguar C13S is guar hydroxypropyltriamonium chloride. Other particularly suitable materials include Jaguar C15, Jaguar C17 and Jaguar C16 and Jaguar C162, A preferred cellulose ether is Polymer JR400.
As discussed above, we have surprisingly found that in compositions of our invention, inclusion of cationic polymer enhances the wet properties of the shampoo without subsequent dry hair sensory negatives such as slippy feel leading to styling difficulties.
Advantageously, the amount of cationic conditioning polymer present in compositions on the invention is not governed by the requirement that these materials should act as a deposition aid for the silicone component. The particular level appropriate in compositions of the present invention is dependent on the particular surfactant system employed. Generally, the level can vary from 0.01 to 3% by weight.
The invention is also directed to the use, in a shampoo composition comprising a major proportion of a surfactant, of an aqueous pre-formed emulsion of an insoluble, non-volatile silicone having an average particle size in the emulsion and in the shampoo composition of from 2 to 30 microns for imparting improved conditioning benefit to hair from the shampoo composition.
The shampoo composition of the invention may further comprise from 0.1 to 5 % of a silicone suspending agent. Examples are polyacrylic acids, cross linked polymers of acrylic acid, copolymers of acrylic acid with a hydrophobic monomer, copolymers of carboxylic acid- containing monomers and acrylic esters, cross-linked copolymers of acrylic acid and acrylate esters, heteropolysaccharide gums and crystalline long chain acyl derivatives. The long chain acyl derivative is desirably selected from ethylene glycol stearate, alkanolamides of fatty acids having from 16 to 22 carbon atoms and mixtures thereof. Ethylene glycol distearate and Polyethylene glycol 3 distearate are preferred long chain acyl derivatives. Polyacrylic acid is available commercially as Carbopol 420, Carbopol 488 or Carbopol 493. Polymers of acrylic acid cross-linked with a polyfunctional agent may also be used, they are available commercially as Carbopol 910, Carbopol 934, Carbopol 940, Carbopol 941 and Carbopol 980. An example of a suitable copolymer of a carboxylic acid containing a monomer and acrylic acid esters is Carbopol 1342. All Carbopol materials are available from Goodrich and Carbopol is a trade mark.
Suitable cross linked polymers of acrylic acid and acrylate esters are Pemulen TR1 or Pemulen TR2. A suitable heteropolysaccharide gum is xanthan gum, for example that available as Kelzan mu.
Depending on the type of composition employed, one or more additional ingredients conventionally incorporated into hair treatment compositions may be included in compositions of the invention. Such additional ingredients include styling agents, such as resins and hair-setting polymers, perfumes, dyes, buffering or pH adjusting agents, viscosity modifiers, opacifiers, pearlescers, preservatives, antibacterial agents, antidandruff agents, foam boosters, proteins, moisturising agents, herb or other plant extracts and other natural ingredients.

Abstract: i) at least one surfactant chosen from anionic, nonionic, zwitterionic or amphoteric surfactants or mixtures thereof:

Abstract: iii) a soluble cationic hair conditioning polymer having a cationic charge density of about +3.0 meq/gram or less,

Abstract: in which the emulsified particles of insoluble, nonvolatile silicone are incorporated into the shampoo composition as a preformed aqueous emulsion having an average silicone particle size in the emulsion and in the shampoo composition of from 2 to 30 microns.


A method is provided for monitoring and controlling the process consistency of an arc welding process. The weld voltage signal is monitored and analyzed to determine the occurrence of the detachment of a weld droplet. The weld droplet detachment is determined via statistical techniques as having occurred at a normal interval following a prior detachment indicating consistent weld process or as a sporadic detachment having occurred at an irregular interval with respect to the prior detachment and indicating inconsistent weld process. The weld process is adjusted by controlling the weld process variables to maximize the predominance of droplet detachment at normal intervals and minimize the occurrence of the sporadic detachments.

Aluminum is an important alternative material to steels for the automotive and other industries due to its superior strength-to-weight ratio. One of the most common joining processes for aluminum is gas metal arc welding (GMAW). In GMAW an electrode creates an arc, and a continuously fed wire electrode is melted by the arc and transferred to the welding pool between the two aluminum workpieces.
Compared to other joining processes, GMAW has many advantages in achieving quality of weld joints and efficiency of production. However, GMAW is a very complicated process involving mechanical, electrical, thermal, chemical and metallurgical phenomena. Thus it can be challenging to maintain stability.
Furthermore, aluminum is much more difficult to weld than steel and is more likely to have weld discrepancies compared to steels. For example, compared to steels, aluminum has higher thermal conductivity, higher rate of thermal expansion and higher solidification shrinkage, thus requiring more intense and tighter controls of heat input. Aluminum also has much higher hydrogen solubility, which results in higher sensitivity to the shielding gas.
In order to ensure GMAW process consistency and weld quality, when welding aluminum as well as other metals, it would be desirable to develop improved on-line weld monitoring methods by which the available process data, such as weld voltage, could be evaluated in a manner that process instability and weld discrepancies could be detected quickly, thus enabling prompt adjustment of weld variables such as arc length, wire feed rate, shielding gas composition and flow rate, welding power source characteristics, in order to bring the welding process back into proper consistency and quality.

Method for controlling the consistency of an arc welding process by monitoring welding voltage to determine weld droplet detachment

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