Abstract:
A drinking straw is disclosed, comprising a surface layer which is a tubular exterior made of polymer; and an inner layer which is made of the same material with the surface layer and foamed to become the inner wall of the surface layer such that the hollow flow path is formed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a drinking straw, and in particular to a drinking straw which can isolate or ease off a certain degree of temperature between lip and fluid when people suck in drinks with the drinking straw.  
       BACKGROUND OF THE INVENTION  
       [0002]     People usually use drinking straws to take in fluid, which is not limited to drinks. With a drinking straw being inserted into the container of drinks, people can suck in drinks. Until now, drinking straw is still one of the most effective tools to take in fluid food.  
         [0003]     People usually drink cold drinks, but hot drinks are not uncommon, for example but not limited to soy bean milk, milk, hot mesona, and so on. In general, people less often use drinking straws to take in hot drinks; instead people use cups, bowls, and so on because conventional prior art of drinking straws are not suitable for taking hot drinks.  
         [0004]     It is known that conventional drinking straws are tubular structure made of thin polymer. The drinking straws made of thin polymer are ineffective in heat insulation, or, to put in more precisely, effective in heat conduction. Consequently, the temperature of hot drinks will effectively transfer to people&#39;s lips. Since human&#39;s lips are sensitive to temperature, people usually feel unbearable when first sucking in hot drinks, and then pour the hot drink into other containers. People usually blow the hot drinks to cool them down when they try to take in the hot drinks.  
         [0005]     U.S. Pat. No. 6,460,776 discloses a heat insulating drinking straw, in which double tubes with a gap between them to slow down heat conduction and in turn achieve a certain degree of heat insulation. Many perspectives, however, can be used to tackle a problem. It is believed that there is a need for further alternative novelty of drinking straws. The drinking straw disclosed in the present invention is aimed to tackle the same problem of heat insulation with a different approach.  
       SUMMARY OF THE INVENTION  
       [0006]     To further explain the details of the drinking straw according to the present invention, please first refer to the schematic figures, wherein  FIG. 1  is a schematic cross-section of a preferred embodiment of a drinking straw according to the present invention and  FIG. 2  is a schematic cross-section of another preferred embodiment of a drinking straw according to the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention can be more fully understood by reference to the following description and accompanying drawings, in which:  
         [0008]      FIG. 1  is a schematic cross section of a preferred embodiment of a drinking straw according to the present invention; and  
         [0009]     FIG  2  is a schematic cross section of another preferred embodiment of a drinking straw according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0010]     Referring to  FIG. 1 , a preferred embodiment of a drinking straw according to the present invention is a long, tubular body which is extruded and then cut to a certain length, comprising a surface layer  11  and an inner layer  12  encompassing a flow path  13 .  
         [0011]     The surface layer can be made of, for example but not limited to, PP, Ps, PE, Nylon, and PET with a preferable thickness of 1˜3 mm. The surface layer  11  is directly in contact with people lips and may therefore, for example but not limited to, be colored or illustrated. However, these prior arts are commonly known and will not be discussed further.  
         [0012]     The inner layer  12 , made of the same material with that of the surface layer  11 , is foamed to become its shape. T foaming ratio of the inner layer is 2 to 10, to form a plurality of cells inside, which can also provide heat insulation. The thickness of the inner layer  12  is preferable 0.3 to 5 mm. More specifically, the outer diameter of the drinking straw  1  is preferably less than 20 mm and the flow path  13 , for the pass of fluid, encompassed by the inner layer  12  is preferably less than 15 mm. As described earlier, a drinking straw according to present invention is produced by extrusion, and thus the inner layer  12  can be foamed during the process of extrusion, which is a conventional prior art and will not be discussed further.  
         [0013]     Referring to  FIG. 2 , another preferred embodiment of a drinking straw according to the present invention is a hexagonal tube, in which the surface layer  11  is a hexagonal cross section and the inner layer  12  forms a circular flow path  13 . Furthermore, with proper mold design, the flow path  13  may be any other shape, corresponding to or not corresponding to the cross section of the surface layer  11  or the inner layer  12 , i.e. the cross section of the flow path may be circular or any other shape. The choice of the cross section of the flow path  13  is a matter of mold design, which will not be discussed further.  
         [0014]     Furthermore, a drinking straw  1  according to the present invention may be made a series of grooves at a proper portion such that the drinking straw  1  can be flexed to facilitate drinking. The process of making such bendable drinking straws is also a conventional prior art and thus will not be discussed further.  
         [0015]     Consequently, by putting the present invention into practice, the main advantages of the present invention includes the following points. 
    (1) Simple manufacturing process: the conventional extrusion process can be used to make the drinking straw according to the present invention and subsequent cutting may also be completed by conventional prior art such that the cost is low and thus suitable for disposable use.     (2) Effective heat insulation: with different thickness of the inner layer and the choice of foaming ratio, the degree of heat insulation can be selected to meet specific demand.    
 
         [0018]     While the invention has been described with reference to the a preferred embodiment thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention, which is defined by the appended claims.