A PACKAGE SYSTEM FOR CHEMICALS

Abstract: The invention relates to chemicals, in particular to agrochemicals, which are packaged in water-soluble containers provided with a buoyancy compartment. The invention also relates to the use thereof for the preparation of aqueous spray mixtures for different fields of use, especially for formulations for agrochemicals for protecting plants and animals from pests or for plant growth regulators.

Description: A package system for chemicals The present invention relates to chemicals, in particular to agrochemicals, which are packaged in water-soluble containers provided with a buoyancy compartment. The invention also relates to the use thereof for the preparation of aqueous spray mixtures for different fields of use, especially for formulations for the application of agrochemicals for protecting plants and animals from pests or for plant growth regulators. EP-A-4497 73 discloses water-soluble bags that contain an agrochemical concentrate and which are so packaged that the user can dissolve the bags, avoiding contact with the chemical, in a water tank to prepare aqueous spray mixtures. A two-compartment package for toxic chemicals is disclosed in WO 93/08095, the chemicals being separated from each other by a two-compartment system and only being mixed upon contact with water when the package dissolves. US-A-5222595 discloses a water-soluble inner and a water-solu¬ ble outer container, both of which are filled with agrochemicals. For a rapid and complete dissolution of the package, the package system itself must float in the water for as long as possible, i.e. sedimentation and possible sticking to the bottom of the water tank must be avoided. When such package systems discharge their contents too early, then thorough mixing is no longer ensured. In addition, residues may form that can only be removed with difficulty. The specific weight of the package system is thus cricial for a successful application of the package. The specific weight can be adjusted by filling the container incompletely; the remainder is then typically air. It has been observed that, during storage, the some of the air escapes. The specific weight changes again with detrimental effect and the problem of complete dispersion remains unsolved. It has now been found that this drawback can be avoided and that storage-stable package systems whose specific weight remains unchanged over an extended period of time can be prepared by providing the chemicals so packaged with a buoyancy compartment. In one of its aspects, the invention relates to a package system comprising at least one water-soluble container filled with a chemical, which package is provided with a buoyancy compartment, such that the specific weight of the entire package system is 1 or less than 1. It is preferred that the specific weight of the package system is only a little less than 1. The buoyancy compartment can be so designed that it is firmly bonded to the water-soluble container or is contained within said container. The buoyancy compartment is filled with an agent that has a specific weight of less than 1. The agent may preferably be a gas such as air or nitrogen. The package system preferably comprises two containers, one of which is water-soluble and contains the chemical, and the other takes the form of a buoyancy compartment. In another preferred embodiment of the invention, the buoyancy compartment is contained within the container filled with chemicals (bag-in-bag system). If the package system is a bag-in-bag system, the wall of the buoyancy compartment is preferably water-soluble. Another, and also preferred, embodiment of the package is that both containers are attached to each other by means of a water-soluble joint which may be in the form of a spot weld, strip weld or linear weld, or of a seam, preferably a welded joint formed by heat sealing. If the buoyancy compartment is bonded to the container for the chemicals by means of a water-soluble joint, then the wall of the buoyancy compartment is preferably made of a water-insoluble polymer. In a particularly preferred embodiment of the invention, the buoyancy compartment is filled with air or nitrogen. The water-soluble wall of the containers preferably consists of natural unmodified or modified polymers or synthetic polymers. The polymers are desirably so chosen that they have a sufficient mechanical stability and do not burst during transportation or if inadvertently dropped. Suitable water-soluble polymers are inert to the chemicals employed, for example organic solvents, surfactants, active compounds and other adjuvants. They may typically include homo- or copolymeric polyalkylene ethers, for example polyethylene glycols or copolyethylene propylene glycols, starch and modified starch, modified celluloses such as partially alkylated and partially acylated celluloses or hydroxyalkylated or carboxyalkylated celluloses (hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose), polyvinyl ethers such as polymethyl vinyl ether, polymethoxyethyl vinyl ether, polyhydroxyethyl vinyl ether, polyhy- droxypropyl vinyl ether and polycarboxymethyl vinyl ether, polysulfonic acids, polysulfates and polycarboxylic acids and the hydroxyalkyl esters and salts thereof, for example polyvinylsulfonic acids or polyvinylsulfates, polystyrenesulfonic acids or sulfated polyphenols, polyacrylic and polymethacryϋc acids, polymaleic acids and the hydroxyethyl esters and salts thereof, sulfonic acid group containing condensates of aldehydes, in particular formaldehyde, and naphthalene, benzene, naphthols, phenols and the salts thereof, low molecular condensates of melamine and/or urea with aldehydes, preferably formaldehyde, polyvinyl pyrrolidones, and polyvinyl alcohol. Particularly suitable copolymers typically include those of at least two monomers selected from the group consisting of vinyl alcohol, vinyl acetate, vinyl ethers, hydroxyalkyl vinyl ethers, acrylic acid, methacrylic acid, maleic acid, maleic acid, hydroxyalkyl acrylates and methacrylates, vinyl pyrrolidone and styrenesulfonic acid. Preferred water-soluble polymers are those containing 50 to 100 mol % of vinyl alcohol units and 50 to 0 mol % of one or more than one comonomer selected from the group consisting of vinyl ether, vinyl acetate, hydroxyalkyl vinyl ether, acrylic acid, methacrylic acid, maleic acid, hydroxyalkyl maleates, acrylates and methacrylates, vinyl pyrrolidone and styrenesulfonic acid. The polymeric wall material is preferably soluble in cold water. To obtain desired mechanical properties, plasticisers may be added to the polymers. In addition, the walls of the containers may also consist of water-soluble polymer mixtures, including polymers mentioned above. Most preferably, the container wall consists of polyvinyl alcohol obtainable by hydrolysis of polyvinyl ethers or esters. The degree of hydrolysis may be from 80 to 92 %, preferably from 86 to 90 %. The buoyancy compartment may be fabricated from different polymeric materials and need not be water-soluble. If it is not water-soluble, it can, for example, simply be scooped from the surface of the water after dissolution of the chemical. The wall of this buoyancy compartment is preferably made from a plastics material selected from the group of the thermoplastic film-forming polymers that has as low an air permeability as possible. It may be selected from one of the following groups of water-insoluble polymers. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, polybut-1-ene, poly-4-methylpent-l-ene, polyisoprene or polybutadiene, as well as poly¬ mers of cycloolefins, for instance of cyclopentene or norbornene, polyethylene (which optionally can be crosslinked), for example high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE). Mixtures of the cited polymers, for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE). Polymers derived from α,β-unsaturated acids and derivatives thereof such as polyacrylates and polymethacrylates. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12. Polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene terephthalate, polybutylene terephthalate, poly-l,4-dimethylolcyclohexane terephthalate and polyhydroxybenzoates, as well as block copolyether esters derived from hydroxyl-terminated polyethers. The buoyancy compartment may be additionally metallised to enhance its gas impermeability. The compartment is preferably coated with an aluminium layer having a thickness of a few micrometers and which may be prepared by vacuum metallising. In order to avoid at all events damage to the water-soluble container during transportation and storage, the package system is additionally provided with a removable outer wrapping of monofilms or laminates comprising at least two sheets of identical or different polymers. The outer wrapping may also consist of different materials, for example plastics, metals and laminates such as paper/plastic, paper/metal, metal/plastic or paper/plastic/metal. The outer wrapping is not contaminated with chemicals and can therefore be readily reused, disposed of or recycled. The outer wrapping is preferably made of a plastic material that may be selected from the aforementioned group of water-insoluble polymers. The wall thickness of the outer wrapping may conveniently be from 10 μm to 10 mm, preferably from 10 μm to 1 mm. The chosen wall thickness will depend, inter alia, on the make-up of the package. Containers in the form of tubular bags are usually thin-walled, whereas erect or free-standing systems are thicker walled. The type of seal can also affect the wall thickness. The chemicals may be inorganic or organic compounds. The organic chemicals can contain minor amounts of water, conveniently up to 5 % by weight, preferably up to 2 % by weight, based on the amount of the contents of the water-soluble container. It is also possible, however, for the chemicals to be in the form of aqueous concentrates if they contain additives that prevent the dissolution of the water-soluble containers. Such additives are typically electrolytes. These concentrates may contain up to 50 % by weight, more preferably from 10 to 40 % by weight, of water (q.v. EP-Al-0518 689). The chemicals are preferably agrochemicals, most preferably herbicides, insecticides, pesticides or fungicides and formulations. These formulations may additionally contain thickeners, salts and formulation assistants. The amount of chemicals contained in the package may be from 100 mg to 10 kg. The content of organic chemicals may be 100 %, based on the volume of the water-soluble container. It may be advantageous, however, to choose a content in the range from 70 to 100 % by volume so as to create an inert gas atmosphere with a specific volume of e.g. nitrogen or argon. This inert gas also induces buoyancy when the bag is put into water, but escapes as soon as the bag containing the chemicals begins to dissolve. The bag can be of any shape. Tubular bags are especially suitable because of the ease with which they can be filled. The thermoplastic shaping possibilities, including compression moulding, injection moulding, deep-drawing techniques or injection blow moulding, permit, however, a wide range of shapes and configurations. The bags may for example have the shape of a sphere, a bag, a tubular bag, a square, a rectangle or a cylinder. Preferred shapes of water-soluble containers are typically bags, tubular bags, multichamber deep-drawing containers. A further object of the invention is the use of the package system for the preparation of aqueous formulations for the application of agrochemicals. The invention also relates to a process for the preparation of aqueous formulations for the application of agrochemicals, which comprises adding the package in a manner known per se to a water tank and stirring until a sprayable suspension or dispersion forms. The following Examples illustrate the invention. Example 1: A fungicidal formulation (gel) is first prepared from the following components: 62.5 % w/w of propiconazol 3.0 % w/w of a mixture of nonylphenol polyglycol ether with calcium dodecylbenzenesulfonate 3.0 % w/w of fatty alcohol polyglycol ether 4.0 % w/w of ethylene oxide/propylene oxide block copolymer 0.2 % w/w of silicone oil 27.3 % w/w of a 5 % solution of a cellulose derivative in cyclohexanone/dipropylene glycol methyl ether The fungicidal mixture has a density of 1.17 g/cm 3 . Half of 250 g of the above described fungicide gel is filled into a water-soluble polyvinyl alcohol bag. A smaller polyethylene bag containing 50 ml of air is prepared separately and heat-sealed gas-tight. This air-filled bag is added to the bag partially filled with chemicals and the other half of the gel formulation is added. The bag is then heat sealed such that it contains as little air as possible to form a two-compartment package system with buoyancy compartment (bag-in-bag system). To prepare a spray mixture, this package is put into water on which it floats. After the outer, water-soluble bag has dissolved and the fungicidal formulation has become homogeneously dispersed, the water-insoluble bag filled with air is scooped from the surface of the water. Example 2: The procedure of Example 1 is repeated, but adding instead of an air-filled polyethylene bag a water-soluble polyvinyl alcohol bag filled with 50 ml of air. After complete dispersion of the fungicidal mixture, stirring is continued until the air-filled bag also dissolves.

Claims: What is claimed is: 1. A package system comprising at least one water-soluble container filled with a chemical, which package system is provided with a buoyancy compartment, such that the specific weight of the entire package system is 1 or less than 1. 2. A package system according to claim 1, which consists of two containers, one of which takes the form of a buoyancy compartment. 3. A package system according to claim 1, wherein the buoyancy compartment is filled with air or nitrogen. 4. A package system according to claim 1, wherein the buoyancy compartment is contained within the container filled with chemicals. 5. A package system according to claim 4, wherein the wall of the buoyancy compartment is water-soluble. 6. A package system according to claim 1, wherein the buoyancy compartment is bonded to the container filled with chemicals by a water-soluble joint. 7. A package system according to claim 6, wherein the wall of the buoyancy compartment is water-insoluble. 8. A package system according to claim 1, wherein the water-soluble wall of the compartment filled with chemicals consists of natural unmodified or modified polymers or synthetic polymers. 9. A package system according to claim 1, wherein the water-soluble wall consists of polymers containing 50 to 100 mol % of vinyl alcohol units and 50 to 0 mol % of one or more than one comonomer selected from the group consisting of vinyl ether, vinyl acetate, hydroxyalkyl vinyl ether, acrylic acid, methacrylic acid, maleic acid, hydroxyalkyl maleates, acrylates and methacrylates, vinyl pyrrolidone and styrenesulfonic acid. 10. A package system according to claim 8, wherein the water-soluble wall consists of polyvinyl alcohol. 11. A package system according to claim 1, wherein the containers are provided with an outer removable wrapping of polymeric monofiϊms or laminates. 12. A package system according to claim 11, wherein the outer wrapping has a thickness of 10 μm to 1 mm. 13. A package system according to claim 1, wherein the chemicals are agrochemicals. 14. A package system according to claim 11, wherein the agrochemicals are selected from the group consisting of herbicides, insecticides, pesticides or fungicides and formulation assistants. 15. A package system according to claim 11, wherein the content of chemicals is from 100 mg to 10 kg. 16. A package system according to claim 11, wherein the containers have the shape of a sphere, a bag, a tubular bag, a square, a rectangle or a cylinder. 17. Use of a package system as claimed in claim 1 for the preparation of aqueous formulations for applying agrochemicals.

Inventors: VOGT MANFRED, VOGT, MANFRED
Applicants: CIBA GEIGY AG, VOGT MANFRED, CIBA-GEIGY AG, VOGT, MANFRED
Application year: 1995
Main classification: B65D65
IPC codes: B65D65