Reivindicaciones

1. A thermal polymeric film for agricultural use that comprises a polyolefin and a mixture of, at least, a compound selected from the group made up of the borates stable at the processing temperature and anhydrous borax (group A) and, at least, a compound selected from the group made up of silica, silicates, carbonates and sulfates (group B) . 2. A polymeric film according to claim 1, in which its composition contains between, approximately, an 85% and, approximately, a 99% in weight of a polyolefin and between, approximately, 1% and, approximately, 15% in weight of the mixture of the compounds of group A and group B. 3. A polymeric film according to claims 1 and 2, in which the weight ratio of the compounds of group A and group B is comprised between approximately 1:5 and approximately 50:1. 4. A polymeric film according to claims 1 to 3, in which said polyolefin is polyethylene, a copolymer of ethylene and an alkyl acrylate, a copolymer of ethylene and an alkyl methacrylate, PVC or mixtures of them. 5. A polymeric film according to claims 1 to 4, in which the additive of group A is zinc borate and the additive of group B is calcined kaolin. 6. A polymeric film according to claims 1 to 4, in which the additive of group A is zinc borate and the additive of group B is silica. 7. A polymeric film according to claims 1 to 6, in which the polyolefin is polyethylene. 8. A polymeric film according to claims 1 to 6 which also comprises additives selected from the group made up of antioxidants, light stabilizers, antidrip additives, antistatics, lubricants and their mixtures. 9. A polymeric film according to claims 1 or 2 in which said film is a single layer film or a multilayer film.