Abstract:
A composition comprising an ethylene (meth)acrylic acid copolymer and an anti-fouling agent is provided. The composition selectively disintegrates in media of different ionic strengths. Also provided is a method of preventing fouling using the composition.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/883,618, filed Sep. 27, 2013, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    This disclosure relates to compositions that selectively disintegrate in media of different ionic strengths. 
       BACKGROUND 
       [0003]    There are multiple conditions where protection of a material or surface in high ionic strength systems would be advantageous. For example, within the home care market, brand owners have moved to more concentrated delivery systems, such as high efficiency concentrated laundry detergents and unit dose products. In these cases, the products as sold are significantly higher in ionic strength than during use. Another area in which a composition is exposed to high ionic strength media is in marine coatings. Thus, there is a need for compositions that do not dissolve in high ionic strength media. 
       BRIEF SUMMARY 
       [0004]    In one aspect, a composition is provided, comprising an ethylene (meth)acrylic acid copolymer, wherein at least a portion of the carboxylic acid groups in the (meth)acrylic acid component are neutralized and an anti-fouling agent. 
         [0005]    In another aspect, a film composition is provided, comprising an ethylene (meth)acrylic acid copolymer and an anti-fouling agent, wherein at least a portion of the carboxylic acid groups in the (meth)acrylic acid component are neutralized, and wherein the ratio of the ethylene component to the (meth)acrylic acid component is about between about 50:50 to 90:10. 
         [0006]    In yet another aspect, a coated article is provided, comprising an article, a coating composition comprising an ethylene (meth)acrylic acid copolymer, wherein at least a portion of the carboxylic acid groups in the (meth)acrylic acid component are neutralized and an anti-fouling agent. The coating composition does not disintegrate in a high ionic strength media, and disintegrates in a low ionic strength media. 
       DETAILED DESCRIPTION 
       [0007]    The present disclosure relates to a chemical composition of an ethylene (meth)acrylic acid copolymer. As used herein, the term “composition” may mean, for example, a mixture, solution, or dispersion. “(Meth)acrylic,” as used herein, means acrylic, methacrylic, or mixtures thereof Ethylene (meth)acrylic acid (EAA) copolymers can be used in a wide variety of applications including high-performance adhesives, flexible packaging films, pouches, and extrusion coating and extrusion lamination applications. The free acid form of ethylene (meth)acrylic acid copolymers can be neutralized to the desired degree with a suitable base. Ethylene (meth)acrylic acid copolymers can be obtained with varying water dispersibility depending on the degree of neutralization. For example, complete water dispersibility, or under certain conditions, complete water solubility, is obtained when the (meth)acrylic acid moiety is completely neutralized with a stoichiometric amount of base whereas partially neutralized EAA copolymers can be water dispersible, water sensitive, or water insensitive depending on the application for which it is aimed. 
         [0008]    The copolymer may be used in various compositions, for example, liquid compositions or film compositions. Such a film could also be physically reduced in size via grinding or other means to provide an encapsulated active ingredient with higher surface area. Similarly sized particles can also be produced from a liquid composition by methods known in the art, such as spray-drying and lyophilization. The composition may comprise a copolymer composition or may comprise a composition and one or more additional materials to provide application specific physical properties (tensile strength, durability, adhesion, etc.). The additional materials may include crosslinking agents, plasticizer agents, disintegrating agents, and/or surfactants. 
         [0009]    The crosslinking agent may include, for example, Ca 2+ , Mg 2+ , Al 3+  or Zn 2+ . In addition to the crosslinking agent, the composition may include at least one additional additive, such as a plasticizing agent, a disintegrating agent, and/or a surfactant, The plasticizing agent may be a hydrophobic plasticizer, a hydrophilic plasticizer, or a combination thereof. For example, the plasticizing agent may be benzyl alcohol, UCON® LB-65 (a polyalkylene glycol (PAG)-based synthetic water insoluble lubricant) T-BEP (tris(butoxyethyl) phosphate, an alkyl phosphate film forming aid and plasticizer), among others. The disintegrating agent may be, for example, acrylic acid, PVOH, a starch, cellulose, or a second co-polymer. The surfactant may be, for example, an anionic surfactant, a non-ionic surfactant, an amphoteric surfactant, or mixtures thereof. Examples of anionic surfactants include those known in the art, such as DOWFAX® 2A1 (alkyldiphenyloxide disulfonate), ammonium lauryl sulfate, sodium lauryl sulfate, sodium laureth sulfate. Examples of non-ionic surfactants include those known in the art, such as polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol octylphenol ethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkyl esters, polyoxyethylene glycol sorbitan alkyl esters, and sorbitan alkyl esters. Examples of amphoteric surfactants include those known in the art, such as Ammonyx® LO (lauramine oxide). 
         [0010]    This composition does not disintegrate in a variety of media in which the ionic strength is very high caustic, household bleach, seawater, synthetic seawater). The term “disintegrate,” as used herein, means dissolve, disperse, or to be soluble. The media may be in the form of for example, a solution, a slurry, a dispersion, or a paste. The media may also be substantially free of substantial amounts of inorganic salts, but the media may include organic amine salts to provide the required ionic strength and alkalinity, Examples of such organic amine salts include mono-, di-, or -substituted alkylamine salts of carboxylic acid and fatty acid esters. High ionic strength media is media with a salt content of greater than about 3 percent, more preferably greater than about 7 percent. Upon exposure to low ionic strength aqueous media (e.g., deionized water, standard tap water, the wash liquid of a laundry machine) the e will break up within minutes, becoming dispersed within the low ionic strength media with gentle agitation. Low ionic strength media is media with a salt content of about 0 to about 2 percent (e.g., tap water, dionized water). 
         [0011]    In marine applications, such as on boats or ships, the salinity of seawater provides the ionic strength required to prevent dissolution or disintegration of the composition, thus, the composition can be used as the basis of a coating, which once applied, can be removed after use via fresh water, i.e., low ionic strength, washing. In addition, the composition may be formulated in such a way that it contains an additive capable of acting as an anti-fouling agent, 
         [0012]    Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or animals on wetted surfaces. Anti-fouling is the process of removing or preventing these accumulations. Examples of anti-fouling agents include, but are not limited to, biocides such as organotin compounds (e.g., the tributylitin moiety (TBT)) and copper compounds (e.g., copper oxide) and coatings based on organic polymers. Coatings based on organic polymers may be hydrophobic, such as those based on fluoropolymers and silicone, or hydrophilic, such as those based on highly hydrated zwitterions (e.g., glycine betaine and sulfobetaine). 
         [0013]    The present composition could be used in any application where it is desirable to prevent growth or fouling, such as in water towers, on docks, on metal dam components, on oil rigs, and on ship hulls. 
         [0014]    In particular embodiments, the composition may comprise an ethylene (meth)acrylic acid copolymer and an anti-fouling agent. At least a portion of the carboxylic acid groups in the (meth)acrylic acid component are neutralized with a base, resulting in a salt. For example, the carboxylic acid groups may be neutralized with a sodium cation to fort sodium salt. In another embodiment, the carboxylic acid groups may be neutralized with a potassium cation to form a potassium salt. The degree of neutralization may be between about 70 percent and about 100 percent, preferably between about 90 percent and about 100 percent, and more preferably between about 98 percent and about 100 percent. In other embodiments, the degree of neutralization may be between about 70 percent and about 95 percent, preferably between about 85 percent and about 95 percent, more preferably between about 90 percent and about 95 percent. A portion or all of the remaining (meth)acrylic acid may be ionically crosslinked. Increasing the degree of neutralization increases the dispersibility of the composition in low ionic strength media. Those skilled in the art recognize appropriate methods for determining degrees of neutralization. See, e.g., U.S. Pat. No. 3,472,825. 
         [0015]    The composition may also comprise water, such that it forms a liquid composition, which may be applied to an article or may be dried to create, for example, a film or particles. In sonic embodiments, the composition may comprise about 60 to about 80 weight percent water. The ethylene (meth)acrylic acid copolymer may be present in a dispersion, which may be formed any number of methods known to those of skill in the art. The weight ratio of the ethylene to (meth)acrylic acid in the copolymer may be between about 50:50 and about 90:10, preferably between about 70:30 and about 90:10, and more preferably between about 75:25 and about 80:20. 
         [0016]    The composition may be used to produce a coated article, for example, a coated ship, dock, or dam. The coated article may comprise the article, the composition comprising an ethylene (meth)acrylic acid copolymer, and the anti-fouling agent. 
         [0017]    Also disclosed are methods of preventing growth or fouling. In such methods, the present composition is applied to an article and prevents the accumulation of microorganisms, plants, algae, or animals on the surface of the article. 
     
    
     EXAMPLES 
     Example 1 
       [0018]    The functionalized polyolefin composition used for this example is a mixture of ethylene (meth)acrylic acid (80 weight percent ethylene and 20 weight percent (meth)acrylic acid) neutralized with potassium hydroxide. The degree of neutralization is 92 percent. The composition be prepared using procedures known in the art. See, e.g., U.S. Patent Application No. 2011/0319521; PCT Published Application No. WO2011034883; and PCT Published Application No. WO2012082624. The composition has a pH of 10 and a Brookfield viscosity of 500 (Brookfield RVT, #2 spindle, 20 RPM, 25° C.). and is hereinafter referred to as EAA-K. 
         [0019]    To the composition of EAA-K (6.6 g, 23% active), 1.3 g of a suspension of copper oxide (46% in water) is added. The material is agitated via manual shaking of the vial to fully suspend the copper particles in the composition. A film is solution cast on glass using a 203 μm (8 mils) draw down bar, followed by drying in a 40 degrees Celsius oven for 1 hour. The film is removed from the glass and shown to be a freestanding film. Five samples of the film (approximately 2 cm×2 cm) are submerged in room temperature deionized water, tap water, synthetic seawater, saturated NaCl solution, and saturated KCl solution, respectively. The vial is inverted in order to achieve agitation. 
         [0020]    In the high ionic strength systems (synthetic seawater, saturated NaCl solution, and saturated KCl solution) the films appear to remain intact, and no color change to the supernatant is observed. This suggests a low level of leaching of film components into the water during the experiment. In the low ionic strength media (deionized water and tap water), the films break apart within five minutes, and the supernatant is observed to have turned brown after allowing the solids to settle, This suggests high levels of leaching of the film during the experiment. 
         [0021]    While the invention has been described above according to its preferred embodiments, it can be modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using the general principles disclosed herein. Further, the application is intended to cover such departures from the present disclosure as come within the known or customary practice in the arm to which this invention pertains and which fall within the limits of the following claims.