MXPA98004771A - Process for increasing the solubility rate of a water soluble film - Google Patents

Abstract

A polymeric film includes at least one irradiated water soluble layer. A process for making a water soluble film includes the steps of extruding a water soluble film;and irradiating the water soluble film. Using electron beam irradiation, a water soluble film's solubility rate can be increased.

Description

PROCESS TO INCREASE THE SPEED OF SOLUBILITY OF A FILM SOLUBLE IN WATER BACKGROUND OF THE INVENTION The present invention relates to a water soluble film, and a process for increasing its solubility rate. Caustic or potentially hazardous materials such as detergents, soaps, plant protection agents, dyes for the textile industry, concrete and ferilizing additives are typically packaged in dispensers, such as high density polyethylene bottles, or other containers. After the chemical content of the container has been used, the spout or empty container must be disposed of in an environmentally safe manner. This can be technically difficult and expensive. Another important issue with the use of such caustic or otherwise potentially hazardous chemicals or other materials is user safety. When installing, using and disposing of spouts or containers containing such materials, the user's safety may be impaired if the disposal or storage system is not handled properly.

- Water soluble films are useful in many applications in addressing these problems. These applications include the packaging of detergents, fertilizers and other products. These films offer the advantage of containing a product within a package made from the film until it is ready for use. When the product is needed, the package is immersed in water or some water-based medium to dissolve the contents of the package in the aqueous medium while additionally dissolving the packaging material itself, These uses offer an environmentally attractive alternative to containers that do not they dissolve, and, therefore, should be discarded after use. However, a problem encountered when using water-soluble films is that in some applications for water-soluble films, rapid dissolution of the film is required. This is important in those applications where the film must dissolve quickly in order to expose the soluble contents in the package within a relatively short time. Therefore, there is a real need in the market to provide a packaging film in a form that conveniently provides the functionality soluble in water at the time when the contained product is to be used. The inventors have found that this can be achieved by providing an irradiated water soluble film. By using electron beam irradiation, the dissolution time of the water-soluble film can be made especially to a certain degree to meet the application requirements.

DEFINITIONS "Soluble in water" as used herein refers to polymeric materials that are soluble in water. "Film" is used herein to mean a film, weft or other packaging material of one or more layers, made by, eg, extrusion, coextrusion, lamination (extrusion system, thermal, or solvent-based coreactive or water-based adhesive), coating or other processes. "PVOH" refers to polyvinyl alcohol. "AAS" refers to acid / acrylate / styrene terpolymer.

COMPENDIUM OF THE INVENTION The invention in a first aspect, is a polymorphic film comprising at least one water soluble layer irradiated. The invention, in a second aspect, is a process for making a water soluble film comprising extruding a water soluble film, and irradiating the water soluble film The invention in a third aspect. is a process for making a water soluble film comprising making a film comprising a water soluble portion and a water insoluble portion; irradiate the film; and remove the water-insoluble portion of the film. The invention in a fourth aspect is - a pad comprising a water soluble article; and a polymeric film comprising at least one irradiated water-soluble layer, the film wrapped around the article.

BRIEF DESCRIPTION OF THE DRAWINGS The invention can be further understood with reference to the drawings, wherein: Figure 1 is a schematic cross section of a film of the present invention; Y Figures 2 to 4 are schematic cross sections of alternative embodiments of the invention.

- ~ DESCRIPTION OF THE PREFERRED MODALITIES Referring to Figure 1, a water-soluble film 10 is shown, having a layer 12.

The film has been extruded by any conventional element, and then sß radiates. The film can be single layer or multi layer construction. One or more of the layers may comprise a water-soluble irradiated material. Figure 2 shows a film d? multiple layers with the layer 12 and the layer 14. Figure 3 shows a multilayer film with the layers 12, 14 and 16. The irradiation can be done by any conventional means. In the irradiation process, the film is subjected to a treatment of energetic radiation, such as corona discharge, plasma, flame, ultraviolet, X-rays, gamma rays, beta rays and electronic treatment of high energy. The irradiation of the polymeric films is described in the patent of E.U.A. No. 4,064,296 to Bornstßin, et al., Which is hereby incorporated in its entirety, by reference thereto. Bornstein et al. describe the use of ionization radiation to crosslink the polymer present in the film. The radiation dosages are referred to herein in terms of the radiation unit of iloGray (kGy) of radiation unit. A suitable radiation dosage of high energy electrons ßs of the scale from 1 to 250 kGy, more preferably around 44-139 kGy, and still more preferably. 80-120 kGy. Preferably, the irradiation is carried out by an electron accelerator and the dosage level is determined by conventional dosimetry methods. Other accelerators, such as a Van de Graaff or resonance transformer can be used. The radiation is not limited to electrons from an accelerator, since any ionization radiation can be used. The most preferred amount of radiation depends on the film and d? its final use. The water-soluble irradiated film can be combined with another film, such as a water-soluble or water-insoluble film 22 as shown in Figure 4. The film 44 itself can be single layer or multi-layer construction. The film 10 and 22 can be produced by any conventional means, including co-extrusion, lamination (extrusion, thermal, or coreactive system of solvent-based adhesive or water-based adhesive), extrusion coating, corona bonding or other appropriate means. The interface between the films 10 and 22 can be removable. A single co-extruded film can be made, having one portion 10 soluble in water and a portion 22 insoluble in water. This film can be irradiated to obtain the benefit of the invention. Suitable materials for water-soluble layer 12 include fully hydrolyzed polyvinyl alcohol; partially hydrolyzed polyvinyl alcohol; polyethers such as polyethylene oxide; acrylate-based polymer such as acid / acrylate copolymer or terpolymer such as ethacrylic acid / ethyl acrylate copolymer and acid / acrylate / styrene terpolymer; styrene maleic anhydride copolymer (SMA); copolymer of ethylene and acrylic acid (EAA), copolymer of ethylene and methacrylic acid (EMAA). or copolymer of ethylene and methacrylic acid neutralized with metal salt known as ionomer, wherein the acid content of EAA and EMAA is at least about 20 mole percent, polylactide (polylactic acid); polysaccharide such as cellulose, such as cellulose ether, such as hydroxypropylcellulose, such as hydroxypropylmethylcellulose. copolymer of polyether polyamide such as polyether block amide copolymer, polyhydroxybutyric acid or polyhydroxyvaleric acid; polyster or water-soluble copolyester; polyethyloxazoline; Polyurethane Soluble in water; Partially acrylated / partially acrylated copolymer neutralized with metallic salt; a mixture of acid / acrylate copolymer and ionomer, or mixtures of any of these materials. Commercial polyvinyl alcohol is available from Air Products. Polyether is available from Mitsubishi Plastics Company. Another commercial example of polyether is available from Planet Polymer Technologies as Enviro Lastic-H- "1. A commercial example of polyethylene oxide is available from Union Carbide as Polyox ™ A commercial example of ethacrylic acid / ethyl acrylate copolymer is available from Belland as GBC 2580 and 2600. The acid / acrylate / styrene terpolymer is available from Belland.A commercial example of styrene-aleadic anhydride copolymer (SMA) is available from Monsanto as Scripset * ". Commercial ionomers are available from du Pont, Polyactide is available from Ecochem and Cargill. Hydroxypropylcellulose is available from Aqualon Division of Hercules as Rlucel "". Hydroxycopropylmethylcellulose is available from Dow Chemical as Methocel * 8. The polyhydroxy butyric acid and the polyhydroxy valeric acid are available from Imperial Chemical Industries as Biopol "". A commercial example of polyethyloxazoline is available from Dow as PEOX 2001. In the case of a water-soluble multilayer film, any of the layers 12 and 14, and any additional layers likewise can be of any of the above-mentioned materials. The water insoluble layers can comprise any suitable material as long as it is substantially insoluble in water and can be adhered detachably to the water soluble substrate.

The water-insoluble layer, if present, may comprise a polymer: metallic foil, film, sheet, or coating; a metallized sheet, film or sheet; a paper or paper coated with a polymer coating such as a high density polyethylene coating; or an inorganic coating such as a silicon coating. Suitable materials for the water-insoluble layer include high density polyethylene; - low density polyethylene; ethylene alpha olefin copolymer such as linear low density polyethylene, very low density polyethylene, ultra low density polyethylene and metallo? ene catalyzed polymer; unsaturated ethylene ester copolymer such as ethylene vinyl acetate copolymer and ethylene alkyl acrylate copolymer; ethylene acid copolymer such as ethylene copolymer acrylic acid and ethylene methacrylic acid copolymer; propylene polymer and copolymer such as metallocene catalyzed propylene copolymer; vinylidene chloride polymer and copolymer; polyvinyl chloride; polyhydroxy-amino ether; polyamide; polyalkylene carbonate; polystyrene; or mixtures of any of these materials. Preferred materials are those that are not only insoluble in water, but also act as moisture barriers. These materials having a moisture vapor transmission rate (MVTR) preferably less than 100, more preferably less than 75, more preferably less than 50, such as less than 25, less than 20, less than 15, less of 10, less than 5, and less than 1 gm / 24 hours. 645 square centimeters (ASTM F 1249 for values of 20 grams or less, ASTM E 96 for values greater than 20 grams) at 100% - RH. Any film 12 or 22 can have up to nine layers or more made of materials such as those mentioned above in any appropriate combination. The film of the present invention can be made in packages such as bags, pockets or other containers, by any known means, including thermoforming. Flange material, horizontal shape-fill-seal, vertical-fill-seal shape, vacuum skin packing, or other means. The invention can be further understood by reference to the examples identified below. Table 1 identifies the resins used in the examples.

TABLE 1 MATERIAL COMMERCIAL NAME SOURCE PVOHt VINEX 2025 AIR PRODUCTS PVOH2 VINEX 2025 + antiblock (Si02) AIR RRODUCTS PVOHa VINEX 2144 AIR PRODUCTS AAS, G70AX-15LA BELLAND Table 2 identifies the three film structures used in the examples and their thicknesses.

- These films were extruded by casting or (for Film A) they were coextruded, and then they ran through an electron beam irradiation dome.

TABLE 2 FILM THICKNESS STRUCTURE (MICROMETERS) A PVOH2 / PVOH3 / 'AAS1 276 B PVOH! 175 C PVOH3 76.2 Table 3 shows the examples done as discussed above, together with the applied dosage (Dj), and in some cases the absorbed dosage (D2). The applied dosage values (D are in milliamps.) The absorbed dosage values (D2) were measured for Examples 1 to 4, but were calculated for Examples 5 to 8. The absorbed dosages were measured by FTIR, using a film of polyethylene as a standard The high energy of the electronic beam causes the formation of crosslinks or double bonds in the amorphous regions of the polyethylene standard due to chain separation and reformation As the electron beam intensity or flow increases, more radiation energy is absorbed - through the polyethylene standard, causing more cross-links to be formed. The subsequent increase in crosslinks is then measured using a FTIR spectrometer by relating the dosing band (transvinylene) to 966 cm'1 to the thickness band at 2017 cm "1. Control Examples 13 to 15 were not irradiated.

TABLE 3 EXAMPLE MOVIE Dj (MA) Dz (kGy) 1 A 1.1 24.6 2 A 3.0 63.7 3 A 5.0 118.0 4 A 10.0 262.0 B 1.1 24.4 6 B 3.0 63.9 7 B 5.0 118.3 8 B 10.0 262.4 9 C 1.1 24.4 C 3. Ó 63.9 11 C 5.0 118.3 12 C 10.0 262.4 13 C 0.0 - 14 A 0.0 - 15 B 0.0 _ - Table 4 shows some of the films in Table 3, along with percent solubility measured at the indicated temperature, time and solvent medium.

TABLE 4 FILM IMPLEMENT SOLVENT TEMP. TIME DI? EUEL- CC) (min.) TO (%) 7 B H20 25 5.0 100.0 11 C HzO 25 4.5 100.0 12 C H20 25 6.0 100.0 13 C H20 6 3.5 100.0 B H20 6 9.0 100.0 8 B H > 0 6 9.5 100.0 12 C H20 6 5.0 100.0 14 A 5% NaOH 26 10.0 4.7 4 A 5% NaOH 26 10.0 3.2 14 A 13pH 71 60.0 40.4 4 A 13pH 71 60.0 94.2 14 * A 13pH 71 60.0 85.2 4 * A 13pH 71 60.0 94.2 2 A 13pH 71 60 0 93.2 • These samples were cut into very small pieces to evaluate the effect of sample geometry on solubility. The remaining samples were cut and They evaluated using large simple pieces of film. "556 NaOH" refers to a 5% caustic solution. Additional samples were tested, as identified in Table 5. Control Example 16 was not irradiated.

TABLE 5 FILM EXAMPLE Th (MA) D2 (kGy) 16 A 0.0 0.0 17 A 3.0 62.8 18 A 3.0 63.6 19 A 10.0 232.0 20 A 10.0 235.4 Table 6 lists the films in Table 5, along with the percent solubility measured at the indicated temperature, time and solvent medium. Samples were cut in approximately 1.16 square centimeters before running in 500 milliliters of 5% NaOH solution with a pH of 13.

- TABLE 6 SOLVENT TEMP. DISSOLVED TIME CC) (min.) (*) 16a A 13pH NaOH 71 30 98.4 16b A 13 H NaOH 71 60 99.0 171 A 13pH NaOH 71 30 100.0 18 »At 13pH NaOH 71 30 100.0 192 A 13pH NaOH 71 30 100.0 'A 13pH NaOH 71 30 100.0 1 sample completely dissolved in 22 to 24 minutes. 2 sample completely dissolved in 10 minutes. The films of the present invention preferably vary in thickness from 0.01 to 0.51 mm and more preferably between approximately 0.05 and 0.38 mm in thickness. The optimum thicknesses will depend at least in part on the intended end use, packaging format and cost considerations. The films of the invention can optionally be biaxially or uniaxially oriented, by any suitable technique well known in the art, such as tension frame or trapped bubble. The oriented film will be thermally shrinkable, but optionally it can be set or thermally annealed to remove all or part of its thermal shrinkage.

Claims (20)

- - CLAIMS

1. - A polymorphic film comprising at least one irradiated layer soluble in water.

2. The film of claim 1, wherein the speed of solubility of the layer is greater than the same layer in a non-irradiated condition.

3. The film of claim 1, wherein the film is irradiated at an absorbed dosage of between 1 and 250 kGy.

4. The film of claim 1, wherein the water soluble layer comprises a material selected from the group consisting of fully hydrolyzed polyvinyl alcohol. partially hydrolyzed polyvinyl alcohol. polyether acrylate-based polymer, styrene-maleic anhydride copolymer, ethylene-acrylic or methacrylic acid ethylene copolymer with an acid content of at least 20 mole percent. ionomer polyactide, polysaccharide, polyether polyamide copolymer, polyhydroxy butyric acid, polyhydroxy valoric acid, polyether, copolyester, polyethyloxazoline. polyurethane. partially neutralized acid-acrylate copolymer with metal salt, a mixture of acid-acrylate copolymer and ionomer, and mixtures of any d? these materials.

5. - The film of claim 1. wherein the percent solubility of the layer is greater than the same layer in a non-irradiated condition.

6. The film of claim 1, wherein the water soluble film comprises an alkaline soluble layer, and a water soluble layer.

7. The film of claim 1, wherein the film is adhered to a second film.

8. - The film of claim 7, wherein the second film comprises at least one layer insoluble in water.

9. The film of claim 8, wherein the insoluble layer in water comprises a material selected from high density polyethylene, low density polyethylene, ethylene alpha olefin copolymer, unsaturated ethylene ester copolymer, ethylene acid copolymer , propylene polymer, propylene copolymer, vinylidene chloride polymer. copolymer of vinylidene chloride, polyvinyl chloride, polyamide, polyalkylene carbonate, polystyrene, polyhydroxy-amino ether, and mixtures of any of these materials.

10. The film of claim 1. wherein the film comprises an alkaline soluble inner layer, an intermediate structural layer, and a layer External soluble in water.

11. A process for making a film soluble in water, comprising: a) extruding a water soluble film; and b) irradiating the water soluble film.

12. The process of claim 11, wherein the water soluble film is irradiated by electron beam radiation.

13. The process of claim 11, wherein the film is irradiated at an applied dosage of between 0.1 and 20 MA.

14. The process of claim 11. wherein the film is irradiated at an absorbed dosage of between 1 and 250 kGy.

15. The process of claim 11, wherein the film is oriented.

16. The process of claim 11, wherein the film is thermally shrinkable.

17. A process for making a water soluble film comprising: a) making a film comprising a water soluble portion and a water insoluble portion; b) irradiate the film; and c) removing the water-insoluble portion of the film.

18. - The process of claim 17. wherein the film is co-extruded.

19. The process of claim 17, wherein the film is a laminate of the water soluble portion and the water insoluble portion.

20. The process of claim 17, wherein the film is oriented.