Plastic portable heat insulation cup

A plastic portable heat insulation cup, comprising:

• a) an external cup made of plastic material by means of an injection molding process, a first lip rim being formed by turning the rim portion of the external cup inside out, a first annular groove with the external wall protruding inward being integrally formed at a place 3-13 mm lower than the first lip rim, the distance from the first annular groove to the inner rim of the cup bottom being marked with h1;
• and
• b) an internal cup made of plastic material by means of an injection molding process, the outer diameter of the internal cup depending on the inclination and the inner diameter of the flank of the external cup, a plurality of corrugations being formed in the flank of the internal cup such that a heat insulation space is created between the corrugations and the flank of the external cup, a second lip rim being formed by turning the rim portion of internal cup inside out, the second lip rim being located at the first lip rim of the external cup, a second annular groove being integrally formed and inwardly protruded at the bottom of the second lip rim, the distance h2 from the second annular groove to the external bottom to the bottom surface of the cup bottom being identical to h1,
• whereby the second annular groove fits just into the first annular groove when the internal cup is placed within the external cup such that a heat insulation cup is created by attaching the external cup and the internal cup to each other.