OIL-BASED ALIPHATIC RESINS, METHOD TO CONTROL THEIR SOFTENING POINTS AND MOLECULAR WEIGHTS, AND THERMOMELTABLE ADHESIVES SENSITIVE TO PRESSURE CONTAINING THEM

The invention provides an oil-based aliphatic resin having: a) A Ring and Ball (R&B) softening point within a range of 75 to 110 degree C; b) a mean molecular weight by weight (Mw) of 1000 to 2600 Dalton, a mean molecular weight-z (Mz) of 1900 to 6000 Dalton, and a Mw/Mn ratio below 2.0; c) a level of aromatic protons below 1.5 percent with respect to total protons as determined by 1H-NMR (Nuclear Magnetic Resonance 1H); and d) a mixed aniline methylcyclohexane turbidity point (MMAP) of 90 degree C or less. The resins, according to the invention, are characterized in that they comprise a high amount of cyclic structures. A method is also disclosed for independently controlling the R&B softening point, and molecular weight of an aliphatic resin composition during the preparation thereof by an oil-based feeding polymerization, said method being characterized in that the amount of cyclic structures in the resins is increased. La invencion proporciona una resina alifática a base de petroleo que tiene: a) Un punto de reblandecimiento de Anillo y Bola (R&B) dentro de la escala de 75 a 110 degree C; b) un peso molecular promedio en peso (Mw) de 1000 a 2600 Dalton, un peso molecular promedio-z (Mz) de 1900 a 6000 Dalton y una relacion de Mw/Mn por debajo de 2.0; c) un nivel de protones aromáticos por debajo de 1.5% con respecto a los protones totales determinados por 1H-NMR (Resonancia Magnética Nuclear 1H); y d) un punto de turbidez de metilciclohexano anilina mezclado (MMAP) de 90 degree C o menos. Las resinas de conformidad con la invencion se caracterizan por una cantidad elevada de estructuras cíclicas. Además se describe un método para controlar independientemente el punto de reblandecimiento R&B y el peso molecular de una composicion de resina alifática durante su preparacion mediante polimerizacion de una alimentacion a base de petroleo, estando caracterizado el método en que la cantidad de estructuras cíclicas en las resinas se incrementa.