1. A method for manufacturing a pneumatic tire including an entire tread rubber or a cap layer, said entire tread rubber or cap layer being formed by using an annular wound body obtained by winding ribbon-like non-vulcanized rubber strips in a spiral manner, and the method including:
a step of fixedly attaching a winding start point of a first rubber strip and a winding start point of a second rubber strip to an object to be wound at positions located further inward in a width direction than the respective sides of the wound body,
a winding step for forming the entire tread rubber or the cap layer, comprising
a first winding step for forming a first layer by spirally winding the first rubber strip towards one side up to the one side and by spirally winding the second rubber strip towards the other side up to the other side, and
a second winding step for successively forming a second layer outside of the first layer by turning the first rubber strip up at the one side and spirally winding the same towards the other side without cutting the same at the one side and by turning the second rubber strip up at the other side and spirally winding the same towards the one side without cutting the same at the other side, and
a step of fixedly attaching a winding end point of the first rubber strip and a winding end point of the second rubber strip at positions located further inward in the width direction than the respective sides of the wound body,
wherein said winding start point of the first rubber strip is provided between the other side of the wound body and a width center of the wound body such that the first rubber strip, at its winding start point, has a side surface, on the side thereof that faces the one side of the wound body, located at the width center, and the winding start point of the second rubber strip is provided between the one side of the wound body and the width center of the wound body such that the second rubber strip, at its winding start point, has a side surface, on the side thereof that faces the other side of the wound body, located at the width center so that the first rubber strip and the second rubber strip intersect with each other at the width center of the wound body in the first winding step.
2. The method for manufacturing a pneumatic tire as claimed in claim 1, wherein the position of the winding end point of the first rubber strip in the width direction is substantially symmetric to the position of the winding end point of the second rubber strip in the width direction with respect to the width center of the wound body.
3. The method for manufacturing a pneumatic tire as claimed in claim 1, wherein the first rubber strip and the second rubber strip are of identical rubber composition and of identical sectional shape.
4. The method for manufacturing a pneumatic tire as claimed in claim 1, further including an under layer forming step for forming an under layer inside of the first layer by spirally winding a rubber strip on the object to be wound from one side to the other side prior to the first winding step.
5. The method for manufacturing a pneumatic tire as claimed in claim 4, further including a middle layer forming step between the under layer forming step and the first winding step for forming a middle layer between the under layer and the first layer by spirally winding a rubber strip from one side to the other side.
6. A pneumatic tire provided with a tread rubber or a cap layer at a tread portion thereof, wherein the entire tread rubber or cap layer is composed of a strip laminated body including:
a first layer composed of a wound body in which a first rubber strip and a second rubber strip, which respectively include winding start points that are located further inside in a width direction than tread edges, are spirally wound towards the tread edges in opposite directions in the width direction up to one side and the other side of the wound body, respectively, such that the winding start point of the first rubber strip is provided between the other side of the wound body and a width center of the wound body and, at its winding start point, a side surface of the first rubber strip, on the side thereof that faces the one side of the wound body, is located at the width center, and the winding start point of the second rubber strip is provided between the one side of the wound body and the width center of the wound body and, at its winding start point, a side surface of the second rubber strip, on the side thereof that faces the other side of the wound body, is located at the width center so that the first rubber strip and the second rubber strip intersect with each other at the width center of the tread rubber; and
a second layer composed of a wound body that is successively formed outside of the first layer by spirally winding the first rubber strip and the second rubber strip towards a tire equator upon turning the same up without cutting the same at tread edges at respective sides thereof with winding end points of the first rubber strip and the second rubber strip being provided further inward in the width direction than the tread edges.
7. A method for manufacturing a pneumatic tire including an entire tread rubber or a cap layer, said entire tread rubber or cap layer being formed by using an annular wound body obtained by winding ribbon-like non-vulcanized rubber strips in a spiral manner, and the method including:
a step of fixedly attaching a winding start point of a first rubber strip and a winding start point of a second rubber strip to an object to be wound at positions located further inward in a width direction than the respective sides of the wound body,
a winding step for forming the entire tread rubber or the cap layer, the winding step consisting of
a first winding step for forming a first layer by spirally winding the first rubber strip towards one side up to the one side and by spirally winding the second rubber strip towards the other side up to the other side, and
a second winding step for successively forming a second layer outside of the first layer by turning the first rubber strip up at the one side and spirally winding the same towards the other side without cutting the same at the one side and by turning the second rubber strip up at the other side and spirally winding the same towards the one side without cutting the same at the other side, and
a step of fixedly attaching a winding end point of the first rubber strip and a winding end point of the second rubber strip at positions located further inward in the width direction than the respective sides of the wound body,
wherein said winding start point of the first rubber strip is provided between the other side of the wound body and a width center of the wound body such that the first rubber strip, at its winding start point, has a side surface on the side thereof that faces the one side of the wound body, located at the width center, and the winding start point of the second rubber strip is provided between the one side of the wound body and the width center of the wound body such that the second rubber strip, at its winding start point, has a side surface, on the side thereof that faces the other side of the wound body, located at the width center so that the first rubber strip and the second rubber strip intersect with each other at the width center of the wound body in the first winding step.
8. A pneumatic tire provided with a tread rubber or a cap layer at a tread portion thereof, wherein the entire tread rubber or cap layer is composed of a strip laminated body consisting of:
a first layer composed of a wound body in which a first rubber strip and a second rubber strip, which respectively include winding start points that are located further inside in a width direction than tread edges, are spirally wound towards the tread edges in opposite directions in the width direction up to one side and the other side of the wound body, respectively, such that the winding start point of the first rubber strip is provided between the other side of the wound body and a width center of the wound body and, at its winding start point, a side surface of the first rubber strip, on the side thereof that faces the one side of the wound body, is located at the width center, and the winding start point of the second rubber strip is provided between the one side of the wound body and the width center of the wound body and, at its winding start point, a side surface of the second rubber strip, on the side thereof that faces the other side of the wound body, is located at the width center so that the first rubber strip and the second rubber strip intersect with each other at the width center of the tread rubber; and
a second layer composed of a wound body that is successively formed outside of the first layer by spirally winding the first rubber strip and the second rubber strip towards a tire equator upon turning the same up without cutting the same at tread edges at respective sides thereof with winding end points of the first rubber strip and the second rubber strip being provided further inward in the width direction than the tread edges.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A method for producing a silica gel, which comprises hydrolyzing a silicon alkoxide and subjecting the resulting hydrogel to a hydrothermal treatment substantially without aging it.
2. The method for producing a silica gel according to claim 1, wherein a hydrogel having a breaking stress of at most 6 MPa is subjected to the hydrothermal treatment.
3. The method for producing a silica gel according to claim 1, wherein the hydrothermal treatment is carried out at a temperature of from 50 to 150 C. for from 1 to 10 hours.
4. The method for producing a silica gel according to claim 1, wherein an ammonia water is used for the hydrothermal treatment.
5. The method for producing a silica gel according to claim 1, wherein an obtained silica gel is a silica gel which has the following characteristics:
(a) the pore volume is from 0.6 to 1.6 mlg,
(b) the specific surface area is from 300 to 900 m2g,
(c) the mode diameter (Dmax) of pores is less than 20 nm,
(d) the volume of pores having diameters within 20% of Dmax is at least 50% of the total pore volume,
(e) it is amorphous, and
(f) the content of metal impurities is at most 500 ppm.
6. The method for producing a silica gel according to claim 1, wherein hydrolysis of said silicon alkoxide is conducted in the absence of a template.
7. A silica gel, produced by a process comprising hydrolyzing a silicon alkoxide and subjecting the resulting hydrogel to a hydrothermal treatment substantially without aging it.
8. The silica gel according to claim 7, wherein a hydrogel having a breaking stress of at most 6 MPa is subjected to the hydrothermal treatment.
9. The silica gel according to claim 7, wherein the hydrothermal treatment is carried out at a temperature of from 50 to 150 C. for from 1 to 10 hours.
10. The silica gel according to claim 7, wherein an ammonia water is used for the hydrothermal treatment.
11. The silica gel according to claim 7, wherein an obtained silica gel is a silica gel which has the following characteristics:
(a) the pore volume is from 0.6 to 1.6 mlg,
(b) the specific surface area is from 300 to 900 m2g,
(c) the mode diameter (Dmax) of pores is less than 20 nm,
(d) the volume of pores having diameters within 20% of Dmax is at least 50% of the total pore volume,
(e) it is amorphous, and
(f) the content of metal impurities is at most 500 ppm.
12. The silica gel according to claim 11, wherein the pore volume is from 0.8 to 1.6 mg.
13. The silica gel according to claim 11, wherein the specific surface area is from 400 to 900 m2g.
14. The silica gel according to claim 11, wherein the mode diameter (Dmax) is at least 2 nm.
15. The silica gel according to claim 11, wherein the volume of pores having diameters within 20% of Dmax is at least 60% of the total pore volume.
16. The silica gel according to claim 11, wherein the content of metal impurities is at most 10 ppm.
17. The silica gel according to claim 11, wherein the content of metal impurities is at most 1 ppm.
18. The silica gel according to claim 11, wherein the differential pore volume at the mode diameter (Dmax) is from 5.0 to 12.0 mlg.
19. The silica gel according to claim 11, wherein the value of Q4Q3 in solid state Si-NMR is at least 1.3.
20. The silica gel according to claim 7, wherein hydrolysis of said silicon alkoxide is conducted in the absence of a template.
21. The silica gel according to claim 11, wherein hydrolysis of said silicon alkoxide is conducted in the absence of a template.
22. A silica gel which has the following characteristics:
(a) the pore volume is from 0.6 to 1.6 mlg,
(b) the specific surface area is from 300 to 900 m2g,
(c) the mode diameter (Dmax) of pores is less than 20 nm,
(d) the volume of pores having diameters within 20% of Dmax is at least 50% of the total pore volume,
(e) it is amorphous, and
(f) the content of metal impurities is at most 500 ppm.
23. The silica gel according to claim 22, wherein the pore volume is from 0.8 to 1.6 mlg.
24. The silica gel according to claim 22, wherein the specific surface area is from 400 to 900 m2g.
25. The silica gel according to claim 22, wherein the mode diameter (Dmax) is at least 2 nm.
26. The silica gel according to claim 22, wherein the volume of pores having diameters within 20% of Dmax is at least 60% of the total pore volume.
27. The silica gel according to claim 22, wherein the content of metal impurities is at most 10 ppm.
28. The silica gel according to claim 22, wherein the content of metal impurities is at most 1 ppm.
29. The silica gel according to claim 22, wherein the differential pore volume at the mode diameter (Dmax) is from 5.0 to 12.0 mlg.
30. The silica gel according to claim 22, wherein the value of Q4Q3 in solid state Si-NMR is at least 1.3.
31. The silica gel according to claim 22, which is produced by means of a step of hydrolyzing a silicon alkoxide.