Biodegradable shotgun cartridge

Abstract

The present invention relates to a biodegradable shotgun cartridge comprising a rim, a case and at least one base wad and at least one container wad, wherein said case, the at least one base wad and at least one container wad comprise (i) at least one biodegradable bioplastic of vegetable or fermentative origin; and (ii) an inert and non-toxic mineral filler, wherein said mineral filler comprises no more than 70% by weight with respect to the total weight of said material.

Claims

1. A biodegradable shotgun cartridge comprising a rim, a case and at least one base wad and at least one container wad, wherein said case, said at least one base wad and said at least one container wad are each made only from biodegradable bioplastic, and wherein said biodegradable bioplastic consists of polylactic acid (PLA) and a biodegradable polymer with elastomeric properties.

2. The biodegradable shotgun cartridge according to claim 1, wherein said biodegradable polymer with elastomeric properties is selected from the group consisting of rubber and latex.

3. The biodegradable shotgun cartridge according to claim 1, wherein said PLA is extracted from cornstarch, potato starch or cellulose.

4. The biodegradable shotgun cartridge according to claim 1, wherein the specific weight of said biodegradable bioplastic is comprised between 0.6 gr/cm.sup.3 and 5 gr/cm.sup.3.

5. The biodegradable shotgun cartridge according to claim 1 further comprising between 1% and 10% by weight with respect to the total weight of said biodegradable bioplastic of a thermoplastic polymer and between 0.5% and 3% of an oxidizing catalyst.

6. The biodegradable shotgun cartridge according to claim 1, wherein said rim is made from the biodegradable bioplastic.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) A bioplastic is a biodegradable plastic of natural origin produced by a living organism, synthesized from renewable energy sources and it does not need catalysts for the biodegradation thereof. In the present invention, bioplastics are understood as those polymers that comply with the EN 13432:2000 standard, i.e., those that biodegrade up to 90% by weight within six months in accordance with ISO standard 14855, i.e., those in which 90% of their mass by weight is transformed into carbon dioxide, water and biomass within 180 days. Preferably, at least 90% by weight disintegrates before 12 weeks to a size of less than 2 millimeters, in accordance with ISO standard 16929. The end products of the aerobic biodegradation of the test material are: carbon dioxide, water, mineral salts, and new microbial cellular constituents (biomass).

(2) Furthermore, other biodegradability standards drafted by different standard bodies (ISO, CEN, ASTM, DIN, etc.). The criteria used for classification are varied: the environment in which the biodegradation occurs, the selected measurement variable, presence or absence of oxygen in the environment, etc. The international standards most commonly used in determining the biodegradability and/or compostability of plastic materials are the following:

(3) UNE-EN-ISO 14852:2005: Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous medium. Method by analysis of evolved carbon dioxide (ISO 14852:1999). Therefore, in one embodiment of the invention, said material is biodegradable in accordance with the UNE-EN-ISO 14852:2005 standard, according to the ISO 14852:1999 analysis method.

(4) UNE-EN-ISO 14855:2005: Determination of the ultimate aerobic biodegradability and disintegration of plastic materials under controlled composting conditions. Method by analysis of evolved carbon dioxide (ISO 14855:1999). Therefore, in one embodiment of the invention, said material is biodegradable in accordance with the UNE-EN-ISO 14855:2005 standard, according to the ISO 14855:1999 analysis method.

(5) UNE-EN-ISO 17556:2005: Determination of the ultimate aerobic degradability in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved (ISO 17556:2003). Therefore, in one embodiment of the invention, said material is biodegradable in accordance with the UNE-EN-ISO 17556:2005 standard, according to the ISO 17556:2003 analysis method.

(6) These test standards are based on the fact that during the biodegradation of the test material in the presence of oxygen, carbon dioxide, water, mineral salts and new biomass products are generated. The percentage of biodegradation is calculated by means of the ratio between the carbon dioxide generated from the test material and the theoretical maximum amount of carbon dioxide that can be produced from the test material.

(7) The requirements that a plastic product has to meet in order to be compostable are set forth by the European EN 13432 standard, and are as follows:

(8) Material analysis: consists in analyzing the material to check its content in heavy metals, total organic carbon, total nitrogen, etc.

(9) Biodegradability: the standard states that at least 90% of the packaging must biodegrade within six months. To check biodegradability, it recommends that ISO standard 14855 should preferably be followed.

(10) Disintegration: checking whether the material is capable of physical degradation into fragments smaller than 2 mm. ISO standard 16929

(11) Compost quality: this is carried out by comparing compost in which plastic samples have been added and a blank (composite without samples). Different parameters (metals, calcium, phosphorus, potassium, etc.) are analyzed to make sure that the compost is suitable for agriculture. Ecotoxicity tests are also carried out on plants, analyzing their growth in substrate to which compost with plastic waste has been added and in a substrate without this waste. OCDE 208 test.

(12) In one embodiment of the invention, the material complies with the OCDE 208 test. In another embodiment of the invention, the material is compostable in accordance with the EN 13432 standard.

(13) The advantages offered by the present invention are based on a biodegradable material made up of biodegradable bioplastics such as polylactic acid, PLA. In addition to the biodegradable bioplastics of vegetable or fermentative origin, the material of the present invention may comprise elastomeric polymers of vegetable origin or mixtures of the same conventional biodegradable polymers such as polycaprolactone. According to another embodiment of the invention, the material of the invention comprises at least one biodegradable thermoplastic bioplastic.

(14) The cartridge of the invention is made up of biodegradable material from renewable energy sources that minimize environmental contamination both in obtaining the raw material, the manufacture thereof and subsequent elimination from the environment. It is a clean and odorless biodegradation produced by microorganisms, fungi and algae. The biodegradable cartridges of this invention do not attract insects and small rodents for the consumption thereof. As a result, this invention provides shotgun cartridges for hunting and sport shooting with the same physical and mechanical characteristics as conventional petrochemical plastics while adding the biodegradable condition thereof.

(15) Bioplastics have the same physical-chemical and thermoplastic properties as polymers made from petroleum, but once disposed of under favorable conditions, they are biodegradable.

(16) According to a preferred embodiment, biodegradable bioplastic is a mixture of a first biodegradable bioplastic with an elastomeric bioplastic. Elastomeric bioplastics are characterized by their great elasticity and ability to stretch and rebound, recovering their original shape once the force that deformed them is removed. They comprise the natural rubbers obtained from natural latex and synthetics. Including elastomeric bioplastics enables obtaining cartridges with the appropriate mechanical properties. In general, it is advisable that the higher the gunpowder charge, the higher the charge of elastomeric bioplastic. In a non-limiting manner, different cases and wads of the biodegradable shotgun cartridges can be carried out, since each cartridge and each wad require different physical-mechanical characteristics, and there are a large variety of cartridges, according to the intended use. Therefore, they may be manufactured using a mixture of bioplastics of vegetable origin such as PLA, plus biodegradable elastomeric polymers, for example, those that comprise at least 90% rubber or latex, of vegetable origin or derived from petroleum, such as, for example, those that comprise at least 90% polycaprolactones, butylene polysuccinate, polyvinyl alcohol, poly (butyl succinate-coadipate). Said biodegradable elastomer, preferably of vegetable origin, is preferably found in proportions of between 10% and 90% by weight with respect to the total weight of the material. According to another particular embodiment, said elastomeric bioplastic is found in proportions of between 20% and 80% by weight with respect to the total weight of the material.

(17) According to an alternative embodiment, the material may also contain small amounts (not more than 10% by weight with respect to the total weight of the material) of thermoplastic polymers accompanied by a catalyst that induces degradation.

(18) In another different embodiment a bioplastic made up of biodegradable elastomeric polymers of vegetable origin is used, which are preferably found in proportions of between 10% and 90% by weight with respect to the total weight of the material. According to another particular embodiment, said biodegradable elastomeric polymers of vegetable origin are found in proportions of between 20% and 80% by weight with respect to the total weight of the material.

(19) The preferred materials for the manufacture of these shotgun cartridges are biodegradable thermoplastics of vegetable origin to which biodegradable thermoplastic polymers derived from petroleum can be added.

(20) According to one embodiment, the biodegradable elastomeric thermoplastics from renewable energy sources are bioplastics formed by elastomeric polymers of vegetable origin such as rubber with not more than 90% by weight with respect to the total weight of the material.

(21) Biodegradable elastomeric thermoplastics derived from petroleum are found in maximum proportions of 60% by weight with respect to the total weight of the material.

(22) The typical proportion of the material is of between 10% and 90% of elastomeric bioplastic with respect to the total weight of the material, for example, between 20% and 85% elastomeric bioplastic with respect to the total weight of the material, preferably between 40% and 80%, more preferably between 50% and 75% by weight with respect to the total weight of the material.

(23) Biodegradable thermoplastics from renewable sources are those made up of bioplastics formed by polymers of vegetable origin with not more than 99% of the mixture, plus a load of inert and non-toxic minerals from the group of carbonates and mineral salts, such as calcium carbonate, sodium bicarbonate or barium sulfate. This group includes bioplastics based on PLA (polylactic acid) copolymer polyesters of the polyhydroxybutyrate (PHB)/polyhydroxyvalerate (PHV) type, and pullulan (a polysaccharide polymer), among others.

(24) According to an embodiment of the invention, a biodegradable and bio-compostable bioplastic represents at least 30% by weight with respect to the total weight of the material, preferably more than 40%, preferably more than 50%, more preferably between 60% and 100%, or between 80% and 100% by weight with respect to the total weight of the material.

(25) In fact, each of the elements of the cartridge (the case, the container wad, the base wad or even the rim) can be made of different bioplastics or different mixtures of bioplastics depending on the mechanical needs of each of them.

(26) The biodegradation property of the variety of shotgun cartridges of this invention, with the different types of biodegradable materials mentioned above, depends mainly on the action of microorganisms and fungi. These microorganisms produce enzymes that catalyze the breakdown of the complex materials used as substrates (polymers) into units that are more susceptible to being assimilated by the microorganisms for the production of biomass.

(27) All these processes are regulated and standardized by European standard EN 13432:2000 Packaging. Requirements for packaging recoverable through composting and biodegradation. Under normal composting conditions, 90% of the mass is biodegraded into carbon dioxide, water, mineral salts and new microbial cellular constituents (biomass), thus achieving biodegradability and complying with current regulations.

(28) In addition to biodegradation, it is important to mention biodisintegration. This occurs in composite materials consisting of a biodegradable component and a non-biodegradable component, wherein at least 90% by weight with respect to the total weight of the material is biodegradable, such as, for example, a mixture of PLA or bioplastics based on starch and PP (polypropylene), a conventional plastic like PVC, in a biodegradable ratio of at least 90% of the mixture. The rest of the material may be the mineral or a conventional thermoplastic and a catalyst to enhance biodegradation thereof. According to one embodiment, the material comprises between 1% and 10% by weight with respect to the total weight of said material of a thermoplastic polymer and between 0.5% and 3% of an oxidizing catalyst.

(29) The cartridges of the invention must have a suitable specific weight such as, for example, in the range of 0.6 gr/cm.sup.3 to 5 gr/cm.sup.3. According to a particular embodiment, the range is located between 0.6 gr/cm.sup.3 and 2.0 gr/cm.sup.3, more specifically between 0.7 gr/cm.sup.3 and 1.8 gr/cm.sup.3, more specifically between 0.8 gr/cm.sup.3 and 1.7 gr/cm.sup.3.

(30) Biodegradable polymers of vegetable origin, including elastomers, form the main base of the mixture, representing no less than 5% and no more than 100% thereof, it being possible to mix them in multiple proportions within this range in order to achieve the physical-mechanical characteristics suitable for the specific use of each cartridge.

(31) Biodegradable polymers of vegetable origin or derived from petroleum, or thermoplastics with catalysts and mineral filler, form the rest of the mixture, it being possible to mix them in multiple proportions in order to achieve the physical-mechanical characteristics suitable for the specific use of each cartridge.

(32) The biodegradable shotgun cartridges of the present invention are made up of a biodegradable polymer case manufactured by an extrusion or injection and molding process, and a base wad and a container wad made up of biodegradable polymers manufactured by an injection and molding process. According to a preferred embodiment, the rim is made up of biodegradable polymers manufactured by an injection and molding process, preferably with a material according to the present invention. Thus, according to one embodiment, said rim is made of metal or of a material comprising (i) at least one biodegradable bioplastic of vegetable or fermentative origin and, (ii) an inert and non-toxic mineral filler, wherein said mineral filler comprises not more than 70% by weight with respect to the total weight of said material.

(33) The present invention is explained by the following example or preferred embodiment, which should not be construed as limiting the scope thereof. Thus, the biodegradable shotgun cartridges proposed in this invention, in addition to a metal rim (for example, brass or steel), consist of a case, a base wad and a container wad and are made of a material comprising the following proportions in relation to weight:

(34) A bioplastic comprised of biodegradable polymers of vegetable origin, such as 60% of PLA, plus 39% of a biodegradable elastomeric polymer and 1% of a calcium carbonate mineral filler, will be used for the base wad and the container wad, manufactured by injection.

(35) A bioplastic comprised of biodegradable elastomeric polymers of vegetable origin, plus a maximum of 5% mineral filler, such as calcium carbonate, sodium bicarbonate or barium sulfate, is used for the case.