Method and apparatus for producing coreless rolls of paper
The mandrel is formed from flexible and elastic material, and after the roll is wound, the mandrel is pulled longitudinally and withdrawn from the roll of paper to form a coreless roll.
1. A roll of wound web material comprising an elongated mandrel and a web convolutely wound around the mandrel, the mandrel being axially elastic and comprised of flexible and elastic material, said flexible and elastic material having a tensile yield strength divided by elastic modulus greater than 2.0%, the mandrel being removable from the wound web.
2. The roll of claim 1 in which the mandrel is tubular.
3. The roll of claim 1 in which the mandrel is solid.
4. The roll of claim 1 in which the mandrel has a substantially uniform cross section for its entire length.
5. The roll of claim 1 in which the mandrel is radially elastic.
6. The roll of claim 1 in which the convolutely wound web material includes a first layer which surrounds the mandrel and which is adhesively attached to the mandrel.
7. The roll of claim 6 in which the adhesive has a viscosity within the range of 3000 to 18,000 cps.
8. The roll of claim 1 in which said flexible and elastic material is thermoplastic.
9. The roll of claim 1 in which the web is bathroom tissue.
10. The roll of claim 1 in which the web is kitchen towel.
11. The roll of claim 1 in which said flexible and elastic material is HDPE.
12. The roll of claim 11 in which the web is bathroom tissue.
13. The roll of claim 11 in which the web is kitchen towel.
14. The roll of claim 1 in which said flexible and elastic material has a tensile yield strength divided by elastic modulus greater than 2.5%.
15. The roll of claim 1 in which said flexible and elastic material has a glass transition temperature of less than 40° F.
16. The roll of claim 1 in which said flexible and elastic material has a glass transition temperature of less than 0° F.
17. The roll of claim 1 in which said flexible and elastic material has a mass density (g/cc) less than 1.25.
18. The roll of claim 1 in which said flexible and elastic material has a mass density (g/cc) less than 1.00.
19. The roll of claim 1 in which said flexible and elastic material has a tensile elastic modulus less than 1,000,000 psi.
20. The roll of claim 1 in which said flexible and elastic material has a tensile elastic modulus less than 500,000 psi.
21. The roll of claim 1 in which said flexible and elastic material has a tensile yield strength less than 25,000 psi.
22. The roll of claim 1 in which said flexible and elastic material has a tensile yield strength less than 15,000 psi.
23. The roll of claim 1 in which said flexible and elastic material has a structure (% crystallinity) greater than 50.
24. The roll of claim 1 in which said flexible and elastic material has a structure (% crystallinity) greater than 75.
25. The roll of claim 1 in which said flexible and elastic material has a Poisson's ratio of greater than 0.35.
26. The roll of claim 1 in which said flexible and elastic material has a Poisson's ratio of greater than 0.40.
27. The roll of claim 1 in which said flexible and elastic material is homogeneous.
28. The roll of claim 1 in which the mandrel has substantially uniform radial stiffness for its entire length.
29. The roll of claim 1 in which said flexible and elastic material is plastic.
30. The roll of claim 1 in which said flexible and elastic material bears the loads imposed by said web wound over said mandrel.
31. A roll of wound web material comprising an elongated mandrel and a web convolutely wound around the mandrel, the mandrel including a pair of end portions and an intermediate portion between the end portions, the intermediate portion being axially elastic and comprised of flexible and elastic material, said flexible and elastic material having a tensile yield strength divided by elastic modulus greater than 2.0%, the mandrel being removable from the wound web.
32. The roll of claim 31 in which said intermediate portion of the mandrel is tubular.
33. The roll of claim 31 in which said intermediate portion of the mandrel is solid.
34. The roll of claim 31 in which said intermediate portion of the mandrel has a substantially uniform cross section.
35. The roll of claim 31 in which said intermediate portion of the mandrel is radially elastic.
36. The roll of claim 31 in which the convolutely wound web material includes a first layer which surrounds said intermediate portion of the mandrel and which is adhesively attached to said intermediate portion of the mandrel.
37. The roll of claim 31 in which said flexible and elastic material is thermoplastic.
38. The roll of claim 31 in which said flexible and elastic material is HDPE.
39. The roll of claim 31 in which said flexible and elastic material has a tensile yield strength divided by elastic modulus greater than 2.5%.
40. The roll of claim 31 in which said flexible and elastic material has at least one of the following properties:
a) a glass transition temperature less than 40° F.;
b) a mass density (g/cc) less than 1.25;
c) a tensile elastic modulus less than 1,000,000 psi;
d) a tensile yield strength less than 25,000 psi;
e) a structure (% crystallinity) greater than 50;
f) a Poisson's ratio greater than 0.35.
41. The roll of claim 31 in which said intermediate portion of the mandrel has substantially uniform radial stiffness.
42. The roll of claim 31 in which said flexible and elastic material is plastic.
43. The roll of claim 31 in which said flexible and elastic material bears the loads imposed by said web wound over said intermediate portion of the mandrel.
44. The roll of claim 31 in which the web is bathroom tissue.
45. The roll of claim 31 in which the web is kitchen towel.