FIELD OF THE DISCLOSURE

[0001] Embodiments disclosed herein relate generally to water-soluble polyvinyl alcohol based films that exhibit stability when in contact with aggressive oxidizing chemicals. More specifically, embodiments disclosed herein relate to vinyl alcohol - vinyl pyrrolidone copolymers, and the use of films from such co-polymers for applications such as unit dose packaging of aggressive oxidizing chemicals.

BACKGROUND

[0002] Polyvinyl alcohol (PVOH) films are often used in the art to form unit dose packages, as the films exhibit good strength, impact resistance, and are soluble in water. The solubility of PVOH films, however, rapidly decreases when exposed to certain chemicals, such as oxidizing chemicals, acid chemicals, alkali chemicals, chlorine-containing substances, salts with polyvalent metals, boric acid, polyamines, insecticides, herbicides, among others. Thus, in applications which employ these types of chemicals, the use of PVOH packaging is restricted, as the effective shelf-life of the unit dose products is limited by their solubility in water.

[0003] Modified PVOH films, having co-monomers and/or various additives, have been shown to improve the chemical resistance of the films. For example, see US6608121, US6166117, US6787512, US6821590, US7005168, and US7745517, among others, disclosing use of various plasticizers, additives, and co-monomers such as N-vinylamide, carboxyl and carboxylate functional groups, and sulfonic acid functional groups.

[0004] US5102950, assigned to Kuraray Co., Ltd., discloses a PVOH film formed from a copolymer consisting of vinyl alcohol units, vinyl ester units, and copolymerization units containing a 2-pyrrolidone ring. Other comonomers are also contemplated, including sulfonic acid groups, quaternary ammonium structures, and others. For use in dose packaging films, it is disclosed to use plasticizers such as a polyhydric alcohol and linear sugar alcohols having 4 to 6 carbon atoms.

[0005] US6956070 and EP1251147, also assigned to Kuraray Co., Ltd., teach that films containing a 2-pyrrolidone ring have a problem of insufficient cold water solubility. Instead, it is disclosed that it is possible to provide a water-soluble film simultaneously satisfying the requirements in regard to water solubility, biodegradability, and physical properties when the PVOH is modified with monomers including an N-vinylamide, a carboxyl group and a lactone ring.

[0006] US6166117, also to Kuraray Co., Ltd., discloses a water-soluble film including a sulfonic acid group modified polyvinyl alcohol in admixture with gallic acid. In this patent, it is noted that 2-acrylamido-2-methylpropanesulfonate-modified polyvinyl alcohols are unsuitable for storage of acidic chemicals for long periods of time, as they lose their function as a water-soluble film. The gallic acid is taught as necessary to achieve the desired properties.

[0007] While many potential solutions have been presented for harsh chemical packaging in the above-noted patents, none have been commercially viable for a diverse range of harsh chemicals under actual user conditions experienced outside the lab, including prolonged storage, variable humidity and temperatures, etc. Such conditions have led to failure of harsh chemical packaging using water soluble polyvinyl alcohol based compositions, including package film discoloration, film degradation or premature breakage, brittleness of the film, poor water solubility, and other insufficient physical and performance properties.

SUMMARY OF THE CLAIMED EMBODIMENTS

[0008] Surprisingly, contrary to the above-noted patents, it has been found that vinyl alcohol - vinyl pyrrolidone copolymers, or mixtures of such copolymers, may be used to provide a water-soluble film while simultaneously satisfying requirements in regard to water solubility, biodegradability, color, and other physical properties, even when used for packaging of a broad variety of harsh, oxidizing chemicals. Further, the films according to embodiments herein may be compatible with multiple types of chemicals, not just select chemicals.

[0009] In one aspect, embodiments disclosed herein relate to a water soluble film useful in unit dose packaging. The water-soluble film may have stability when contacted with harsh chemicals, such as aggressive oxidizing chemicals, and may include: a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 20 mole percent of a pyrrolidone comonomer; and a water-soluble saccharide. [0010] In another aspect, embodiments disclosed herein relate to a unit dose package including: a polymeric dissolution packet comprising the film as described above; and a harsh chemical sealed in the polymeric dissolution packet.

[0011] In another aspect, embodiments disclosed herein relate to a unit dose package.

The unit dose package may include: a polymeric dissolution packet comprising a film; and a chemical sealed in the polymeric dissolution packet. The film may comprise a plasticizer and a polyvinyl alcohol copolymer A consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 20 mole percent of a pyrrolidone comonomer, the copolymer having a degree of hydrolysis in the range from about 65% to about 99%. The chemical may include a peroxide, a nitrate, a nitrite, a chromate, a persulfate, a borate, a bromate, a chlorate, a periodate, a chlorite, a chlorinated or brominated isocyanurate, an inorganic acid, an organic acid, a peroxy acid, or potassium superoxide, or salts and hydrates of these compounds. The film may have a %dissolution by weight in water at 21°C of at least 85 wt% following exposure to the chemical and aging at a temperature in the range from about 30°C to about 54°C for at least 4 weeks, such as in the range from about 4 weeks to about 12 weeks.

[0012] In some embodiments, the chemical is selected from the group consisting of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3- chloro -5,5-dimethylhydantoin, l,3-dibromo-5,5-dimethylhydantoin, 2,3-dibromo-3- nitrilopropionamide; 2-bromo-2-nitro- 1,3 -propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate. In some embodiments, the chemical is undiluted.

[0013] In some embodiments of the unit dose package, the plasticizer is a solid at room temperature and pressure.

[0014] In some embodiments of the unit dose package, the film may further include a polyvinyl alcohol copolymer B containing: (a) from 94 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 6 mole percent of a comonomer comprising sulfonic acid groups. [0015] In some embodiments of the unit dose package, the film may also include an additive selected from the group consisting of dextrose, a bromine scavenger, a chlorine scavenger, ammonium chloride, citric acid, starch, potassium bicarbonate, ammonium chloride, polypropylene glycol, starch, and sodium bisulfite.

[0016] In some embodiments of the unit dose package, the film may have one or more of the following properties when tested according to ASTM D882:

a. a 10% modulus at equilibrium conditions of 30°C and 20% relative humidity of at least 40 MPa;

b. a tensile strength at equilibrium conditions of 30°C and 20% relative humidity of at least 60 MPa;

c. an elongation at break at equilibrium conditions of 30°C and 20% relative humidity in the range from about 20% to about 80%;

d. have an elongation at break at equilibrium conditions of 23°C and 50% relative humidity in the range from about 100% to about 250%; e. a 100% modulus at equilibrium conditions of 23°C and 50% relative humidity in the range from about 15 to about 40 MPa;

f. an elongation at break at equilibrium conditions of 10°C and 70% relative humidity in the range from about 15% to about 260%;

g. a 100% modulus at equilibrium conditions of 10°C and 70% relative humidity in the range from about 9 to about 25 MPa.

[0017] In some embodiments of the unit dose package, the plasticizer may comprise alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, each individually present in an amount in the range from about 1 wt% to about 12 wt%, based on a total weight of the film. In some embodiments of the unit dose package, the plasticizer may comprise alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, each individually present in an amount in the range from about 2 wt% to about 4 wt%, based on a total weight of the film.

[0018] In another aspect, embodiments herein are directed toward a water-soluble film having stability with harsh chemicals. The film may include a plasticizer and a polyvinyl alcohol copolymer A having a degree of hydrolysis in the range from about 65% to about 99% and consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 20 mole percent of a pyrrolidone comonomer. The film may have a %dis solution by weight in water at 21°C of at least 85 wt% following exposure to a chemical and aging at a temperature in the range from about 30°C to about 54°C for at least 4 weeks, such as 4 to 12 weeks, wherein the chemical is selected from the group consisting of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3- chloro-5,5-dimethylhydantoin, l,3-dibromo-5,5-dimethylhydantoin, 2,3-dibromo-3- nitrilopropionamide; 2-bromo-2-nitro- 1,3 -propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate.

[0019] In some embodiments, the film is compatible with each of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3-chloro-5,5-dimethylhydantoin, l,3-dibromo-5,5-dimethylhydantoin,

2,3-dibromo-3-nitrilopropionamide; 2-bromo-2-nitro- 1 ,3-propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate.

[0020] In some embodiments of the film, the plasticizer may comprise alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, each individually present in an amount in the range from about 1 wt% to about 12 wt%, based on a total weight of the film. In other embodiments, the plasticizer may comprise alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, each individually present in an amount in the range from about 2 wt% to about 4 wt%, based on a total weight of the film.

[0021] In various embodiments, the water-soluble film has a %dissolution by weight in water at 21°C of at least 85 wt% following exposure to a chemical and aging at a temperature in the range from about 40°C to about 54°C for at least 8 weeks. In other embodiments, the film has a %dissolution by weight in water at 21°C of at least 85 wt% following exposure to a chemical and aging at a temperature in the range from about 50°C to about 54°C for at least 12 weeks, such as 12 to 20 weeks. [0022] In some embodiments, the plasticizer is a solid at room temperature and pressure. In some embodiments, the plasticizer may have at least 2 hydroxyl groups per molecule. In some embodiments, the plasticizer may be present in an amount of 1 to 10 parts per hundred parts polyvinyl alcohol copolymer A.

[0023] The polyvinyl alcohol copolymer A may contain from 2 to 12 mole percent of the pyrrolidone comonomer. In other embodiments, the polyvinyl alcohol copolymer A may contain from 3 to 7 mole percent of the pyrrolidone comonomer.

[0024] The water-soluble film may also include an additive selected from the group consisting of dextrose, a bromine scavenger, a chlorine scavenger, ammonium chloride, citric acid, starch, potassium bicarbonate, ammonium chloride, polypropylene glycol, starch, and sodium bisulfite. In some embodiments, the additive is a crystalline solid at room temperature and pressure. For example, the film may include dextrose, wherein the dextrose is present in an amount in the range from about 1 to about 10 parts per hundred parts polyvinyl alcohol copolymer A.

[0025] In some embodiments, the film may include an additive selected from the group consisting of dextrose, a bromine scavenger, a chlorine scavenger, ammonium chloride, citric acid, starch, potassium bicarbonate, ammonium chloride, polypropylene glycol, starch, and sodium bisulfite. In some embodiments, the additive is a crystalline solid at room temperature and pressure.

[0026] The water-soluble film may further include a polyvinyl alcohol copolymer B comprising: (a) from 94 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 6 mole percent of a comonomer comprising sulfonic acid groups.

[0027] In another aspect, embodiments herein are directed toward a water-soluble film having stability with harsh chemicals. The film may include a plasticizer and a polyvinyl alcohol copolymer A consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 20 mole percent of a pyrrolidone comonomer. The film may have a tensile strength at equilibrium conditions of 30°C and 20% relative humidity of at least 60 MPa when tested according to ASTM D882. [0028] In other embodiments, the film may have a 10% modulus at equilibrium conditions of 30°C and 20% relative humidity of at least 40 MPa when tested according to ASTM D882. In yet other embodiments, the film may have an elongation at break at equilibrium conditions of 30°C and 20% relative humidity in the range from about 20% to about 80% when tested according to ASTM D882.

[0029] The water-soluble film may have a %dissolution by weight in water at 21°C of at least 85 wt% following exposure to a chemical and aging at a temperature in the range from about 30°C to about 54°C for at least 4 weeks, wherein the chemical is selected from the group consisting of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3-chloro -5,5-dimethylhydantoin, 1,3-dibromo- 5,5-dimethylhydantoin, 2,3-dibromo-3-nitrilopropionamide; 2-bromo-2-nitro- 1 ,3- propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate.

[0030] The water-soluble film may include a plasticizer that is a solid at room temperature and pressure. The water-soluble film may also include an additive, wherein the additive is a crystalline solid at room temperature and pressure.

[0031] In another aspect, embodiments herein are directed toward a water-soluble film having stability with multiple harsh chemicals. The film may include a plasticizer and a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 1 to 20 mole percent of a pyrrolidone comonomer. The film may be compatible with each of the following chemical groups: peroxides, nitrates, nitrites, chromates, persulfates, borates, bromates, chlorates, periodates, chlorites, chlorinated or brominated isocyanurates, inorganic acids, organic acids, peroxy acids, superoxides, and salts and hydrates of these compounds.

[0032] The water soluble film according to some embodiments herein may be compatible with each of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3-chloro-5,5-dimethylhydantoin, l,3-dibromo-5,5- dimethylhydantoin, 2,3-dibromo-3-nitrilopropionamide; 2-bromo-2-nitro- 1 ,3- propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate.

[0033] In some embodiments, the plasticizer may include alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, and when present, each is individually present in an amount in the range from about 1 wt% to about 12 wt%, based on a total weight of the film. In other embodiments, the plasticizer may include alkoxylated trimethylol propane, trimethylol propane, or diglycerine, or a combination thereof, and when present, each is individually present in an amount in the range from about 2 wt% to about 4 wt%, based on a total weight of the film.

[0034] In some embodiments, the film may have a %dissolution by weight in water at

21°C of at least 85 wt% following exposure to a chemical and aging at a temperature in the range from about 30°C to about 54°C for 4 to 12 weeks, wherein the chemical is selected from the group consisting of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3-chloro -5,5-dimethylhydantoin, 1 ,3-dibromo-5,5-dimethylhydantoin, 2,3-dibromo-3-nitrilopropionamide; 2-bromo-2- nitro- 1,3 -propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate.

[0035] In some embodiments, the films according to embodiments herein may exhibit chemical compatibility and may have one or more of the following properties when tested according to ASTM D882:

a. a 10% modulus at equilibrium conditions of 30°C and 20% relative humidity of at least 40 MPa;

b. a tensile strength at equilibrium conditions of 30°C and 20% relative humidity of at least 60 MPa;

c. an elongation at break at equilibrium conditions of 30°C and 20% relative humidity in the range from about 20% to about 80%;

d. have an elongation at break at equilibrium conditions of 23 °C and 50% relative humidity in the range from about 100% to about 250%; e. a 100% modulus at equilibrium conditions of 23°C and 50% relative humidity in the range from about 15 to about 40 MPa;

f. an elongation at break at equilibrium conditions of 10°C and 70% relative humidity in the range from about 15% to about 260%;

g. a 100% modulus at equilibrium conditions of 10°C and 70% relative humidity in the range from about 9 to about 25 MPa.

[0036] Other aspects and advantages will be apparent from the following description and the appended claims.

DETAILED DESCRIPTION

[0037] In one aspect, embodiments disclosed herein relate to water-soluble polyvinyl alcohol based films that exhibit resistance to aggressive oxidizing chemicals. More specifically, embodiments disclosed herein relate to vinyl alcohol copolymers including a comonomer having a pyrrolidone ring substituent group, such as vinyl pyrrolidone, and the use of films from such copolymers for applications such as unit dose packaging of aggressive oxidizing chemicals.

[0038] Vinyl alcohol copolymers useful in embodiments disclosed herein may be formed via the copolymerization of a vinyl ester monomer and the pyrrolidone comonomer via bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like.

[0039] Vinyl esters monomers may include various aliphatic acids, such as vinyl formate, vinyl acetate, vinyl butyrate, vinyl pivalate, isoprenyl acetate, and vinyl versatate, among others.

[0040] Pyrrolidone comonomers may include compounds having a polymerizable carbon-carbon double bond and a pyrrolidone ring substituent group represented by the following formula:

wherein Ri, R2, R3, R4, Rs and R ₆ are each individually selected from a hydrogen atom or an alkyl group, such as an alkyl group having 1 to 8 carbon atoms. Examples of the group represented by the general formula (I) are 2-oxopyrrolidin-l-yl group, 3- propyl-2-oxopyrrolidin-l-yl group, 5-methyl-2-oxopyrrolidin-l-yl group, 5,5- dimethyl-2-oxopyrrolidin-l-yl group, 3,5-dimethyl-2-oxopyrrolidin-l-yl group, and the like. The carbon-carbon double bond contained in the pyrrolidone comonomer may include vinyl, allyl, styryl, acryloxy, methacryloxy, vinyloxy, allyloxyl, and other groups, that are copolymerizable with the above noted vinyl esters of aliphatic acids and have a high alkali resistance at the time of copolymer hydrolysis to form the vinyl alcohol copolymer. Examples of the pyrrolidone comonomers may include N- vinyl-2-pyrrolidone, N -vinyl-3 -propyl-2-pyrrolidone, N- vinyl-5-methyl-2- pyrrolidone, N- vinyl-5 ,5-dimethyl-2-pyrrolidone, N -vinyl-3 ,5-dimethyl-2- pyrrolidone, and N-allyl-2-pyrrolidone, among others.

[0041] The vinyl ester copolymer thus obtained may be saponified to form a vinyl alcohol copolymer. The resulting vinyl alcohol copolymer may have a degree of hydrolysis in the range from about 65 to about 99%, in some embodiments; in the range from about 75 to about 95% in other embodiments, as indicated by C ¹³ NMR analyses. The copolymer may have a relative molecular weight indicated by a characteristic viscosity in the range from about 2 to about 50 cps, in some embodiments; in the range from about 3 to about 30 cps or from about 7 to about 10 cps in other embodiments, where the viscosity is determined on a 4 wt% solution of the polymers in water, measured on a Brookfield viscometer at 20°C.

[0042] The saponified copolymer may have from about 1 mole% to about 20 mole% of the pyrrolidone comonomer in some embodiments. In other embodiments, the saponified copolymer may have from about 2 mole% or 3 mole% to about 15 mole% pyrrolidone comonomer, such as from about 4 mole% to about 12 mole% or from about 5 mole% to about 10 mole%. In other embodiments, the copolymer may include the pyrrolidone comonomer in an amount ranging from a lower limit of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mole% to an upper limit of 8, 9, 10, 11, 11, 13, 14, 15, 16, 17, 18, 19, or 20 mole%, where any lower limit may be combined with any upper limit. In some embodiments, the copolymer is essentially free of other comonomers.

[0043] The vinyl alcohol copolymers described above, including pyrrolidone comonomers, may be used to form water soluble films, such as for unit dose packaging or other applications where water solubility of the film is a desired characteristic. In particular, such films may advantageously be used for unit dose packaging of harsh chemicals, where the unit dose package has a useful shelf life, even when stored at elevated temperature conditions for extended periods of time, such as those that may occur in storage facilities and/or during shipping.

[0044] In some embodiments, water soluble film formulations useful in embodiments herein may include a blend of the vinyl alcohol copolymer and a saccharide component. The saccharide component includes at least one water soluble saccharide, i.e., has a solubility in water at 25°C of at least 0.1 moles per liter. The saccharide component may include oligosaccharides, disaccharides, monosaccharides, or combinations thereof. The saccharide component, as defined herein, does not include polysaccharides (starches) or sugar alcohols. Non-limiting examples include glucose (dextrose), galactose, sucrose, fructose, lactose, maltose, mannose, trehalose, and combinations thereof. The saccharide component is preferably a mono- or di saccharide, and is preferably crystalline. In some embodiments, the saccharide component may be a solid at room temperature and pressure, and may be a crystalline solid.

[0045] The film formulations generally include the vinyl alcohol copolymer as the primary component. The saccharide component may be present in amounts ranging from about 1 wt% to 40 wt% in some embodiments; from about 1 wt% to about 25 wt%, from about 1 wt% to about 10 wt%, or from about 1 wt% to about 5 wt% in other embodiments. In other embodiments, the saccharide component may be present in an amount ranging from a lower limit of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 wt% to an upper limit of 10, 15, 20, 25, 30, 35 or 40 wt%, where any lower limit may be combined with any upper limit.

[0046] In some embodiments, the films may further include a chlorine scavenger or a bromine scavenger in amounts in the range from about 0.25 wt% to about 5 wt%, such as from about 0.5 wt% to about 2.5 wt%, or from about 1 wt% to about 2 wt%. Suitable chlorine scavengers may include thiosulfate salts, such as sodium thiosulfate. Other chlorine scavengers useful in embodiments herein may include: polymers such as polyethylene imines, polyamines, polyamineamides and polyacrylamides; anions selected from the group consisting of reducing materials like sulfite, bisulfite, thiosulfite, thiosulfate, iodide, nitrite, etc.; and antioxidants like carbamate, ascorbate, etc. and mixtures thereof. Conventional non-chlorine scavenging anions like sulfate, bisulfate, carbonate, bicarbonate, nitrate, chloride, borate, phosphate, condensed phosphate, acetate, benzoate, citrate, formate, lactate, salicylate, etc. and mixtures thereof can be used with ammonium cations. Further examples of chlorine scavengers useful in embodiments herein include ammonium sulfate (preferred), and primary and secondary amines of low volatility such as ethanolamines, amino acids and their salts, polyamino acids and their salts, fatty amines, glucoseamine and other aminated sugars. Specific examples include tris(hydroxymethyl) aminomethane, monoethanol amine, diethanol amine, sarcosine, glycine, iminodiacetic acid, lysine, ethylenediamine diacetic acid, 2,2,6,6-tetramethyl piperinol, and 2,2,6,6-tetramethyl piperinone.

[0047] Other components may also be added to the film compositions. For example, minor amounts of plasticizers, in addition to the saccharide component (the inclusion of the saccharide component may have some plasticizing effect on the film). Examples of plasticizers useful in embodiments disclosed herein may include polyethylene glycol (PEG), polypropylene glycol, polyglycerol, trimethylene glycol, trimethylol propane, alkoxylated trimethylol propane, 2,2,4-trimethyl- 1, 3 -pentanediol, pentaerythritol, or glycerine. Other additives useful in embodiments herein may include biocides, fillers, extenders, antiblocking agents, anti-slipping agents, detackifying agents, anti-foaming agents, UV stabilizers, lubricants, release agents, pigments, and dyes, among other additives. In various embodiments, additives may include at least one of starch, diisopropanol amine (DIPA), ammonium chloride, sodium bisulfite, citric acid, potassium bicarbonate, and ammonium chloride. Plasticizers and additives may each be used, in some embodiments, in amounts ranging from about 0.1 to about 25 wt%, such as in the range from about 1 to about 20 wt% or from about 1 to about 15 wt%, from about 1 to about 10 wt%, or from 1 to about 5 wt% in other embodiments. In other embodiments, the plasticizers and/or additives may be individually present in an amount ranging from a lower limit of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 wt% to an upper limit of 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, or 25 wt%, where any lower limit may be combined with any upper limit.

[0048] In some embodiments, for example, the plasticizers and/or additives used may be a solid at room temperature. Additionally, or alternatively, the plasticizers and/or additives may have a relatively high molecular weight, such as greater than about 100 or 120 g/mol, and/or may contain multiple hydroxyl groups, such as 2, 3, 4, or more hydroxyl groups per molecule, for example. The high molecular weight and high melting point (solid at room temperature), may contribute to hindered migration of a harsh chemical within a film composition, for example, and such plasticizers and additives may thus impart desirable physical, mechanical, and chemical characteristics to the resulting films. While not wanting to be bound by any particular theory, room temperature solid or crystalline plasticizers and additives may more effectively hinder migration of chemicals into the film, improving the stability and structure of the film while concurrently maintaining solubility of the water-soluble polymer. High molecular weight plasticizers and additives, and/or those with significant hydrogen bonding capability, such as those with 2, 3, 4, or more hydroxyl groups, may likewise contribute to hindered migration, for example.

[0049] In some embodiments, the plasticizer used may include alkoxylated trimethylol propane, trimethylol propane, diglycerine, or a combination thereof, each individually present in an amount in the range from about 1 wt% to about 12 wt%, based on a total weight of the film. In other embodiments, the plasticizer used may include alkoxylated trimethylol propane, trimethylol propane, diglycerine, or a combination thereof, each individually present in an amount in the range from about 2 wt% to about 4 wt%, based on a total weight of the film.

[0050] Films formed from the vinyl alcohol copolymers described above, including pyrrolidone comonomers, may have physical properties that contribute to the performance of the resulting film, such as when used in harsh chemical packaging, for example. The properties of the resulting films may depend upon a variety of factors, including composition (comonomer content, plasticizer content, additive content), film thickness, polymer molecular weight, as well as the environment in which the film is tested in (temperature, relative humidity). Exemplary physical properties of films useful in some embodiments herein are provided in the Table below.

Table

[0051] The values in the above chart are based on tests performed according to

ASTM D882. [0052] As exemplified in the table above, embodiments of the vinyl alcohol copolymers described above, including pyrrolidone comonomers, may have physical properties beneficial to their performance for containing harsh, oxidizing chemicals. In some embodiments, for example, a 40-60 micron film as described herein may have a 10% modulus at equilibrium conditions of 30°C and 20% relative humidity of at least 40 MPa, such as a 10% modulus at equilibrium conditions of 30°C and 20% relative humidity in the range from about 45 to 100 MPa, such as in the range from 50 to 75 MPa. In other embodiments, for example, a 40-60 micron film as described herein may have a tensile strength at equilibrium conditions of 30°C and 20% relative humidity of at least 60 MPa, such as from about 70 to about 150 MPa, or from about 80 to about 130 MPa. In other embodiments, for example, a 40-60 micron film as described herein may have an elongation at break at equilibrium conditions of 30°C and 20% relative humidity in the range from about 25% to about 100%, such as from about 20% to about 80%, or from about 25% to about 65%. In other embodiments, for example, a 40-60 micron film as described herein may have an elongation at break at equilibrium conditions of 23°C and 50% relative humidity of less than 250%, such as from about 100% to about 250%, or from about 150% to about 220%. In other embodiments, for example, a 40-60 micron film as described herein may have a 100% modulus at equilibrium conditions of 23 °C and 50% relative humidity of at least 15 MPa, such as in the range from about 15 to about 40 MPa, or in the range from about 18 to about 36 MPa. In other embodiments, for example, a 40-60 micron film as described herein may have an elongation at break at equilibrium conditions of 10°C and 70% relative humidity of less than 300%, such as in the range from about 15% to about 260%, or in the range from about 20% to about 250%, or in the range from about 25% to about 200%. In other embodiments, for example, a 40-60 micron film as described herein may have a 100% modulus at equilibrium conditions of 10°C and 70% relative humidity of at least 9 MPa, such as in the range from about 9 to about 25 MPa, or in the range from about 10 to about 15 MPa. In other embodiments, for example, a 40-60 micron film as described herein may have a combination of two or more of the above-described property ranges.

[0053] In some embodiments, the vinyl alcohol copolymers described above, including pyrrolidone comonomers, may be used in admixture with one or more additional polyvinyl alcohol copolymers to form films and unit dose packages, among other useful products. The additional polyvinyl alcohol copolymers may include, for example, polyvinyl alcohol copolymers including comonomers containing sulfonic acid groups. Examples of the comonomers containing sulfonic acid groups may include vinyl sulfonic acid, allyl sulfonic acid, ethylene sulfonic acid, 2-acrylamido-l- methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2- methacrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl acrylate, and salts thereof, among others, where the comonomers may be incorporated into the polymer in amounts ranging from about 1 to about 6 mole% (94 to 99 mole percent of vinyl alcohol and vinyl ester monomer), such as in the range from about 2 to about 5 mole% or from about 3 to about 4.25 mole% in other embodiments.

[0054] As described in the Examples below, blends of the pyrrolidone containing polyvinyl alcohol copolymers and sulfonic acid group containing polyvinyl alcohol copolymers may result in improved unit dose packaging, where it its theorized that the AMPS containing copolymer may provide for enhanced solubility while the pyrrolidone containing copolymer may provide for color stability and/or flexibility of the film, even after exposure to harsh chemicals for extended periods of time at elevated temperatures.

[0055] The blends of the pyrrolidone containing polyvinyl alcohol copolymers and sulfonic acid group containing polyvinyl alcohol copolymers may contain from 10 to 90 wt% of the pyrrolidone containing polyvinyl alcohol copolymers and from 90 to 10 wt% of the sulfonic acid group containing polyvinyl alcohol copolymer in some embodiments; from 15 to 85 wt% of the pyrrolidone containing polyvinyl alcohol copolymers and from 85 to 15 wt% of the sulfonic acid group containing polyvinyl alcohol copolymer in other embodiments; and from 20 to 80 wt% wt% of the pyrrolidone containing polyvinyl alcohol copolymers and from 80 to 20 wt% of the sulfonic acid group containing polyvinyl alcohol copolymer in yet other embodiments, the above percentages based on the total amount of polyvinyl alcohol copolymers. In some embodiments the blends may include from about 20 to 30 wt% of the pyrrolidone containing polyvinyl alcohol copolymers and from about 70 to 80 wt% of the sulfonic acid group containing polyvinyl alcohol copolymer, based on the total amount of polyvinyl alcohol copolymers. In other embodiments, the water- soluble film may include the pyrrolidone containing polyvinyl alcohol copolymers (A) and the sulfonic acid group containing polyvinyl alcohol copolymer (B) at a weight ratio A:B in the range from about 1:4 to about 4:1, such as at a weight ratio of A:B in the range from about 1:2.5 to about 1:3.25. In yet other embodiments, the blends may include the pyrrolidone containing polyvinyl alcohol copolymer in an amount ranging from a lower limit of 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85 wt% to an upper limit of 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 wt%, based on the total amount of polyvinyl alcohol copolymers, where any lower limit may be combined with any upper limit. In yet other embodiments, the blends may include the sulfonic acid group containing polyvinyl alcohol copolymer in an amount ranging from a lower limit of 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85 wt% to an upper limit of 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 wt%, based on the total amount of polyvinyl alcohol copolymers, where any lower limit may be combined with any upper limit.

[0056] The components of the film formulations may be blended together prior to film fabrication by any suitable means. For example, the saccharide component and/or chlorine scavenger may be dissolved in and/or blended with the vinyl alcohol copolymer or an aqueous solution of the vinyl alcohol copolymer.

[0057] The blend may then be used to produce water soluble films. Suitable film forming methods may include film casting, wet process film formation, dry process film formation, film extrusion, melting film formation, coating process and blown film methods, among others.

[0058] In some embodiments, the film may be formed by a solution casting processes.

An aqueous solution of the film may be prepared at about 10 to 30 percent solids by weight. The solution may then be added to a trough on a metal forming belt and a doctor blade spreads the solution out on the belt to a predetermined thickness. The belt is then passed through an oven to evaporate the water, which dries the film to a moisture content of about 6 to 15%. The polymer films may be fabricated to thickness in ranges of from about 10 to 200 microns, for example, such as from about 20 to 150 microns, or from about 50 to about 100 microns. [0059] The water soluble films that may be produced with the vinyl alcohol copolymers described herein are useful for any purpose where water solubility is an advantage. As noted earlier, the films are particularly suitable for unit-dose packaging of harsh oxidizing chemicals, such as may be found in agricultural chemicals, microbiocides and the like, where the chemicals in unit dose packaged form may be placed into water so that the contents are dissolved or dispersed in the water. This is accomplished without the necessity of the user directly touching the harmful chemicals, and without the need to measure the chemicals, as the unit dose package contains a known quantity of the chemical. Examples of chemicals that may be packaged using films according to embodiments herein may include: peroxides such as barium peroxide, sodium carbonate peroxide, calcium peroxide, hydrogen peroxide, lithium peroxide, magnesium peroxide, strontium peroxide, zinc peroxide, and sodium peroxide; ketone peroxides such as acetone peroxide, methyl ethyl ketone peroxide, and benzoyl peroxide; nitrates such as aluminum nitrate, potassium nitrate, silver nitrate, calcium nitrate, sodium nitrate, cupric nitrate, lead nitrate, magnesium nitrate, strontium nitrate, nickel nitrate, and guanidine nitrate; nitrites such as sodium nitrite; chromates and dichromates such as potassium dichromate, sodium dichromate, and ammonium dichromate; sulfates and persulfates such as sodium bisulfate, ammonium persulfate, potassium persulfate, potassium peroxymonosulfate, and sodium persulfate; borates and perborates such as sodium perborate; carbonates and percarbonates, such as sodium carbonate, sodium bicarbonate, sodium percarbonate; perbromates and bromates such as potassium bromate and sodium bromate; permanganates such as potassium permanganates, sodium permanganate, and ammonium permanganate; chlorides, such as calcium chloride; chlorates and perchlorates including barium chlorate, calcium chlorate, sodium perchlorate (monohydrate), strontium chlorate, magnesium perchlorate, zinc chlorate, sodium chlorate, ammonium perchlorate and potassium chlorate; periodates and iodates such as sodium periodate and potassium periodate; chlorites and hypochlorites such as lithium hypochlorite, calcium hypochlorite, and sodium chlorite; chlorinated and/or brominated isocyanurates such as sodium dichoroisocyanuric acid, potassium dichloroisocyanuric acid, and trichloroisocyanuric acid; inorganic acids such as nitric acid, chromic acid, and perchloric acid; peroxy acids such as meta- chloroperoxybenzoic acid; organic acids, such as tartaric acid, fumaric acid, and oxalic acid; bromine, chlorine, iodine and fluorine; potassium superoxide; hydrates of any of the preceding; and combinations of any of the preceding.

[0060] The films are particularly suitable to produce unit dose packaging for sanitizing chemicals such as those used to disinfect pools, spas, and potable water. Sanitizing chemicals include chlorine-containing compounds which produce hypochlorous acid when contacted with water. Hypochlorous acid is the effective sanitizing agent, and the amount of hypochlorous acid which can be produced by a sanitizing chemical relative to chlorine gas (Ck) is referred to as“available chlorine content.” The sanitizing agents may be provided as powder, granules, tablets, liquid, gel, or any other suitable form. Sanitizing agents include hypochlorite salts such as sodium hypochlorite, calcium hypochlorite, and lithium hypochlorite; chlorinated isocyanurates such as dichloroisocyanuric acid (also referred to as “dichlor” or dichloro-s-triazinetrione, 1 ,3-dichloro- 1 ,3,5-triazinane-2,4,6-trione) and trichloroisocyanuric acid (also referred to as “trichlor” or l,3,5-trichloro-l,3,5- triazinane-2,4,6-trione). Salts and hydrates of the sanitizing compounds are also contemplated. For example, dichloroisocyanuric acid may be provided as sodium dichloroisocyanurate, sodium dichloroisocyanurate acid dihydrate, among others. Bromine containing sanitizing agents may also be suitable for use in unit dose packaging applications, such as l,3-dibromo-5,5-dimethylhydantoin (DBDMH), 2,2- dibromo-3-nitrilopropionamide (DBNPA), dibromocyano acetic acid amide, 1-bromo- 3-chloro-5,5-dimethylhydantoin; and 2-bromo-2-nitro- 1,3-propanediol (BNPD,

Bronopol), among others.

[0061] The films described above may be formed into unit dose packaging by adding a predetermined amount of the harsh chemical, in granular, powder, liquid or tablet form, to the film and hermetically sealing the film around the oxidizing chemical to produce a dissolution packet that includes the active chemical agent.

[0062] The films described above may exhibit stability when in contact with harsh chemicals, including aggressive oxidizing chemicals. Stability, as used herein, refers to the films ability to maintain various physical and chemical properties, even under elevated temperature and long-term storage conditions, including a high degree of water- solubility, such as >85 wt% dissolution at 21°C, low discoloration, and chemical resistance.

[0063] While various pyrrolidone comonomers are noted above, experimentation to date has shown that a synergistic effect may result with use of N-vinyl-2-pyrrolidone as the comonomer and dextrose as an additive. Such films may exhibit many of the properties of plasticized PVOH films, but may retain a high degree of flexibility and film integrity, but without loss of water solubility, even following exposure of the films to the harsh chemicals noted above. Such properties are desirable in harsh chemical packaging, as some handling is required for ultimate delivery of the unit dose package to the end target before dissolution, where such handling is typically performed after the film of the unit dose package has been aged or heat aged while in contact with the harsh chemical.

[0064] As described above, polyvinyl alcohol (PVOH) copolymers according to embodiments herein may be useful in harsh chemical packaging. In some embodiments, the composition may include a water-soluble saccharide, such as dextrose, and a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer, and (b) from 1 to 20 mole percent of a pyrrolidone comonomer, such as N-vinyl pyrrolidone. The polyvinyl alcohol copolymer may have a degree of hydrolysis in the range from about 65% to about 99%.

[0065] Film compositions disclosed herein may exhibit stability, including low discoloration and solubility in water, even after exposure to harsh chemicals and heat aging. In some embodiments, the film compositions disclosed herein may exhibit essentially no yellowing when exposed to a harsh chemical and aged at a temperature in the range from about 5°C to about 54°C for at least 4 weeks, such as at a temperature in the range from about 30°C to about 54°C for at least 4 weeks, at least 8 weeks, or at least 12 weeks. Essentially no yellowing, as used herein, refers to maintenance of a clear color, or the occurrence of a slight haze to a light yellowing in color due to reaction of the polyvinyl alcohol copolymer with the harsh chemical during the heat aging period.

[0066] While it is desirable to have 100% dissolution of the film compositions, some insolubility may result due to reaction of the polyvinyl alcohol copolymer with the hash chemical. Film compositions disclosed herein may nonetheless retain a high degree of solubility in water, after heat aging. For example, in some embodiments, the film compositions may have a percent dissolution by weight in water at 21°C of at least 85 wt%, even following exposure to a harsh chemical and aging at a temperature in the range from about 5°C to about 54°C for at least 4 weeks, such as 4 to 12 weeks. Some embodiments may retain a percent dissolution by weight in water at 21°C of at least 90 wt%, even following exposure to a harsh chemical and aging at a temperature in the range from about 30°C to about 54°C for at least 6 weeks, 8 weeks, 12 weeks, or longer.

[0067] As noted above, the polyvinyl alcohol copolymers and film compositions disclosed herein may be useful in unit dose packages, including unit dose packages for harsh chemicals.

[0068] In some embodiments, the unit dose package may include a polymeric dissolution packet and a harsh chemical, where the polymeric dissolution packet includes: from 60 to 95 weight percent of a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 4 to 12 mole percent of a pyrrolidone comonomer; from 1 to 40 weight percent dextrose; and from 1 to 5 weight percent polyethylene glycol. In other embodiments, the unit dose package may include a polymeric dissolution packet and a harsh chemical, where the polymeric dissolution packet includes: from 60 to 95 weight percent of a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 4 to 12 mole percent of a pyrrolidone comonomer; from 1 to 10 weight percent dextrose; and from 1 to 20 weight percent polyethylene glycol. Such dissolution packets may be suitable for harsh chemicals such as dichloroisocyanuric acid, trichloroisocyanuric acid, and calcium hypochlorite, among others.

[0069] In some embodiments, the unit dose package may include a polymeric dissolution packet and a harsh chemical, where the polymeric dissolution packet includes: from 60 to 95 weight percent of a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 4 to 12 mole percent of a pyrrolidone comonomer; from 1 to 40 weight percent dextrose; and from 1 to 15 weight percent of at least one of trimethylol propane and alkoxylated trimethylol propane. In other embodiments, the unit dose package may include a polymeric dissolution packet and a harsh chemical, where the polymeric dissolution packet includes: from 60 to 95 weight percent of a polyvinyl alcohol copolymer consisting essentially of: (a) from 80 to 99 mole percent of vinyl alcohol and vinyl ester monomer; and (b) from 4 to 12 mole percent of a pyrrolidone comonomer; from 1 to 10 weight percent dextrose; and from 1 to 20 weight percent of at least one of trimethylol propane and alkoxylated trimethylol propane. The polymeric dissolution packet may further include from 0.5 to 3 weight percent of at least one of ammonium chloride, citric acid, starch, potassium bicarbonate, and sodium bisulfite, and/or from 0.5 to 10 weight percent glycerine, such as 0.5 to 5 weight percent glycerine. Such a dissolution packet may be suitable for harsh chemicals such as l-bromo-3-chloro-5,5-dimethylhydantoin, 2-bromo-2- nitro- 1,3 -propanediol, l,3-dibromo-5,5-dimethylhydantoin, 2,3-dibromo-3- nitrilopropionamide, and dibromocyano acetic acid amide, among others.

[0070] Film compositions disclosed herein, as noted above, may be exhibit stability, including low discoloration and a high degree of solubility in water, even after exposure to harsh chemicals and heat aging. Such findings are in direct contrast to prior art teachings indicating that pyrrolidone containing polymers and sulfonate containing polymers are unsuitable for such applications, teaching instead that intricate tetrapolymers and specific additives are necessary. In contrast to these teachings, the compositions disclosed herein unexpectedly provide for the desired stability without requiring such intricate measures.

[0071] EXAMPLES

[0072] The compositions described herein were tested to determine their performance characteristics when used in harsh chemical packaging. The testing was performed according to the following test description. Films are prepared from the formulations by casting an aqueous solution of the composition onto a glass plate, which is leveled by gravity and allowed to dry to a moisture content in the range from about 6 wt% to about 15 wt%. An amount of the solution is added to the plate to provide for a film with a target thickness, which may depend on the sample target, such as 38 micron (about 1.5 mil), 50 micron (about 2 mil), 63 micron (about 2.5 mil), and 76 micron (about 3.0 mil), as noted in the tables below. The water in the solution is allowed to evaporate, and the resulting films are cut into an approximately 7.6 cm by 7.6 cm square (a 3-inch by 3-inch square) or a 7.6 cm by 6.3 cm rectangle (a3-inch by 2.5- inch rectangle), as indicated. The film is then folded in half and three sides of the film are heat-sealed using a hand held heat-sealing gun. The resulting pouch is then filled with 15-20 grams of a harsh chemical, which may be in granular form, for example, and the fourth side of the pouch is heat sealed. The filled pouches are stored side-by- side in low density polyethylene bags between blue paper towels (to check for bleaching). The filled pouches are then stored at selected temperature conditions and ambient humidity, and aged for a selected time period. Following aging, the filled pouches are cut open and the chemical is removed. The film thickness is measured and color recorded, and the film is tested for water solubility. A sample of the film is mounted in a slide frame and placed in a 500 ml beaker filled with 400 ml water. The beaker is placed on a magnetic stirrer, and the water is stirred with a magnetic stir bar such that a vortex is created. The water temperature is maintained as noted, such as at about 21°C. The frame is secured in the beaker with a clamp which is supported by a platform such that stirring water pushes against the film. The film begins to balloon or wave. The disintegration time is recorded when the film balloon bursts. After disintegration, the frame remains in water and the dissolution time is recorded as the total time (inclusive of disintegration time) when no residual strings of film and no film particles remain on the frame. Following 15 minutes, the dissolution test is terminated and the percentage of the film dissolved is measured via filtration across a 325 mesh screen.

[0073] The vinyl alcohol - vinyl pyrrolidone compositions used in the Examples herein are summarized in Table 1. The following key may be used to discern the abbreviations as used in the tables below.

Plasticizer: G : Glycerin; Digly: diglycerine; PEG: Polyethylene glycol (number average MW 200 - 1000); TMP: trimethylolpropane; PG: Propylene glycol; ATMP : Alkoxylated- trimethylolpropane;

² Additive: D: Dextrose; CC : Citric acid; KC: Potassium chloride; NH4CI: Ammonium Chloride; St: Starch; Eryt : Pentaerythritol; DIPA : Diisopropanolamine;

NaBS: Sodium bisulfite (used as additive and chemical) ³ Chemical: Dichlor: Dichloroisocyanuric acid; CalHypo: Calcium hypochlorite; Trichlor: Trichloroisocyanuric acid; BCDMH: l-bromo-3-chloro -5,5- dimethylhydantoin; DBDMH: l,3-dibromo-5,5-dimethylhydantoin; DBNPA: 2,3- dibromo-3-nitrilopropionamide; BNPD (Bronopol) : 2-bromo-2-nitro-l,3- propanediol;

⁴ Package coloration after aging; O: no coloration, D: slightly yellow, X: discolored and brown.

Table 1

[0074] The above-described examples were compared to films formed from a vinyl alcohol - AMPS (2-acrylamido-2-methylpropanesulfonic acid) copolymer, having about 4 mole % AMPS. The compositions of the comparative examples are as detailed in Table 2.

Table 2

[0075] Tables 3 and 4 provide the test conditions and results for the samples and comparative samples.

Table 3.

Table 4.

[0076] Table 5 summarizes some of the test results for samples and comparative samples used with a dichlorinated harsh chemical, such as dichloroisocyanuric acid, dichloro-s-triazinetrione or l,3-dichloro-l,3,5-triazinane-2,4,6-trione. Table 5

[0077] Table 6 summarizes test conditions and results for some of the samples and comparative samples used with a trichlorinated harsh chemical, such as trichloroisocyanuric acid or l,3,5-trichloro-l,3,5-triazinane-2,4,6-trione.

Table 6

[0078] Table 7 summarizes test conditions and results for some of the samples and comparative samples used with calcium hypochlorite as the harsh chemical.

Table 7 - Calcium Hypochlorite

[0079] Tables 8 and 9 summarize test conditions and results for some of the samples and comparative samples used with a bromicide, l-bromo-3-chloro-5, 5- dimethylhydantoin (BCDMH), and a bronopol, 2-bromo-2-nitro- 1,3-propanediol (BNPD). Table 8 - BCDMH

Table 9 - BNPD

[0080] Tables 10 and 11 (A and B) summarize test conditions and results for some of the samples and comparative samples used with l,3-dibromo-5,5-dimethylhydantoin (DBDMH), 2,2-dibromo-3-nitrilopropionamide (DBNPA), or dibromocyano acetic acid amide. Table 10 - DBDMH

Table 11A-DBNPA

Table 11B - DBNPA [0081] As shown by the above examples, vinyl alcohol - vinyl pyrrolidone copolymers may be suitable for use in packaging harsh chemicals. Specifically, various samples retained a clear appearance, indicating a high film stability (i.e., high resistance to attack by the harsh chemicals). Further, even where some color formation occurred, the samples retained excellent water solubility and physical strength. Accordingly, samples assessed as A or“slightly yellow” were deemed compatible with the packaged chemicals, since there are many applications where slight discoloration is not of concern for a customer as long as the film maintains its requisite solubility and other physical properties. Film compositions disclosed herein may thus be suitable for use as a harsh chemical packaging film, even where significant aging times may lapse at elevated temperatures prior to use of the packet by an end consumer.

[0082] As described above, it has also been found that the vinyl alcohol copolymers containing pyrrolidone comonomers may be advantageously used in admixture with polyvinyl alcohol copolymers including comonomers containing sulfonic acid groups. Films and unit dose packages were formed with a mixture of VOH-NVP copolymer (5 mole% NVP) and VOH-AMPS copolymer (4 mole% AMPS), as formulated in Table 12. The unit dose packages were contacted with various chemicals and tested according to the procedures described above (2,2-dibromo-3-nitrilopropionamide (DBNPA) at 54°C), the results of which are shown in Table 13, and various comparisons are shown in Tables 14A and B.

Table 12

Table 13

Table 14A Table 14B

[0083] Testing was performed on various additional vinyl alcohol - vinyl pyrrolidone copolymer compositions that may be suitable for use in packaging harsh chemicals. The vinyl alcohol - vinyl pyrrolidone compositions used in the Examples detailed below are summarized in Table 15.

Table 15.

[0084] The compositions described in Table 15, as well as those in Tables 1 and 2, were tested to determine their performance characteristics when used in additional harsh chemical packaging, using the test method outlined above. The tests were performed for comparative purposes, as well as to determine suitability of the compositions for storing additional harsh chemicals. Table 16 provides the test conditions and results for the various compositions tested. Table 16.

[0085] As shown in the Examples above, various formulations formed from combinations of vinyl alcohol - vinyl pyrrolidone copolymer, plasticizer(s), and additive(s) have been found to perform exceptionally well for long-term storage of harsh chemicals, even at elevated temperatures. These exceptional films perform well when storing harsh chemicals, and can be distinguished over formulations that contain glycerine, for example, among other various plasticizers commonly noted as useful in prior patents. A couple of the many samples that failed are detailed in Tables 17 (composition) and 18 (test conditions and results).

Table 17.

Table 18.

[0086] The interaction between the water-soluble polymer, the plasticizer(s), additives(s), and the chemical stored may have a significant impact on the suitability of a film for harsh chemical storage and handling. Common or preferred plasticizers, such as glycerine, for example, have been found to be inappropriate for use with some harsh chemicals, resulting in poor film performance. However, plasticizers generally considered less optimal, such as those that are a solid at room temperature, trimethylol propane for example, have been found to perform extremely well, as exemplified by the numerous examples above.

[0087] Further, while many of the patents cited in the Background section above describe storage of some harsh chemicals, they generally only provide example data using mild chemicals. In contrast, the Examples above clearly show that compositions according to embodiments herein may be used, successfully, for long term storage of a wide variety of harsh chemicals, even at elevated temperatures. Films made according to embodiments herein may be compatible with each of the following chemical groups: peroxides, nitrates, nitrites, chromates, persulfates, borates, bromates, chlorates, periodates, chlorites, chlorinated or brominated isocyanurates, inorganic acids, organic acids, peroxy acids, superoxides, and salts and hydrates of these compounds. For example, films according to embodiments herein may be compatible with each of dichloroisocyanuric acid, calcium hypochlorite, trichloroisocyanuric acid, l-bromo-3-chloro -5,5-dimethylhydantoin, 1,3-dibromo- 5,5-dimethylhydantoin, 2,3-dibromo-3-nitrilopropionamide; 2-bromo-2-nitro- 1 ,3- propanediol, sodium bisulfate, tartaric acid, fumaric acid, oxalic acid, sodium percarbonate, sodium carbonate, sodium bicarbonate, cyanuric acid, and potassium monopersulfate. “Compatible” as used herein refers to the film exhibiting stability during storage of a chemical, including no or minimal package film discoloration, maintenance of flexibility and structural integrity of the film, and exhibiting acceptable water solubility, following extended exposure to the chemical.

[0088] It is additionally noted that the type and amount of additives and plasticizers used may impact convertibility of the admixture into a useful film. To be commercially useful, the films produced need to have desirable mechanical and physical properties, as well as the aforementioned chemical resistance. Films as described herein may have a modulus, elasticity, and tensile strength, as described above, that are suitable for converting the films into end products, such as unit dose packs.

[0089] Some embodiments, for example, may utilize plasticizers and/or additives that are solid at room temperature, thus imparting desirable physical, mechanical, and chemical characteristics to the resulting films. Theorizing, these types of plasticizers and additives may more effectively hinder migration of the harsh chemicals into the film, improving the stability and structure of the film while concurrently maintaining solubility of the water-soluble polymer. High molecular weight plasticizers and additives, and/or those with significant hydrogen bonding capability, such as those with 2, 3, 4, or more hydroxyl groups, may likewise contribute to hindered migration, for example.

[0090] As described above, embodiments disclosed herein relate to water-soluble polyvinyl alcohol compositions and films formed therefrom that exhibit resistance to aggressive oxidizing chemicals. Advantageously, embodiments disclosed herein may provide for water soluble film compositions that exhibit stability, retaining a high degree of water solubility, a high degree of film integrity, and a high degree of flexibility, as well as low discoloration, even following extended exposure to harsh chemicals at elevated temperatures. Such films may thus be suitable for use in unit dose packaging of harsh chemicals, providing an extended shelf life, handling safety, and other benefits as may be readily envisioned by one skilled in the art.

[0091] While the disclosure includes a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the present disclosure. Accordingly, the scope should be limited only by the attached claims.