JPH01204803A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the deformation of the tire at vulcanization, so as to improve its quality by applying an electron beam to each of the inner face side of a carcass ply and the outer face side of an inner liner in a shoulder area, so that a preliminary vulcanized area is formed inside the cord of the carcass ply. CONSTITUTION:A carcass ply 2 which is composed of rubber 3 and a cord 4 is provided for a tire. And an inner liner 7 which is made of rubber is arranged outside the carcass ply 2 in radial direction. In this case, an electron beam irradiated range 14 is provided on the inner face side of the carcass ply 2 located in the shoulder area 13 of the tire. And also an electron beam irradiated range 15 is provided on the outer face side of the inner liner 7, which is opposite to the irradiated range 14. And irradiated ranges 14, 15 are overlapped to fit integrally into each other by accumulating the carcass ply 2 and the inner liner 7 so that a preliminary vulcanized range 16 which is located in the inside area rather than the cord 4 of the carcass ply 2 can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire in which a pre-vulcanization area is provided inside the cords of the carcass ply at the shoulder portion of the pneumatic tire.

Generally, pneumatic tires are manufactured by sequentially laminating carcass ply, belt, tread rubber, etc. on the outside of an inner liner to form a green tire, and then vulcanizing this green tire. However, by performing this vulcanization, the cords of the carcass ply may protrude from the inner surface of the tire at the shoulder portion, or may come up near the inner surface. This is because rubber flows and deforms outward when subjected to internal pressure during vulcanization, but the cord hardly stretches or deforms even when subjected to internal pressure, so the position of the cord within the ply changes to the inner side of the tire. It is thought that this is because the shoulder portion expands and deforms to a greater extent than other portions before contacting the vulcanization mold.

As mentioned above, if the cord protrudes from the inner surface of the tire, it can damage the tube in the case of a tube-filled tire, and reduce the internal pressure retention or deteriorate the physical properties of the cord due to moisture absorption in the case of a tubeless tire. There is a problem of lowering the

In order to solve these problems, a pneumatic tire has been proposed, for example, as described in Japanese Patent Application Laid-Open No. 50-3182. This product uses an electron beam to irradiate the flat carcass ply before the tire is assembled and molded to the area that corresponds to both shoulders when it is molded as a pneumatic tire, and also uses such carcass ply to A pneumatic tire is molded to provide a pre-vulcanization area inside the carcass ply cords, which prevents the carcass ply cords in both shoulder areas from approaching the inner surface of the tire during vulcanization. be.

However, in such pneumatic tires, only one tire component 1, for example, the carcass ply, is irradiated with an electron beam to provide a pre-vulcanized area, so the thickness of the pre-vulcanized area is large. The cord is thin, and as a result, there is a problem in that it cannot sufficiently prevent the cord from approaching the inner surface of the tire.

. Firstly, in pneumatic tires constructed by sequentially laminating carcass ply, belt, and tread rubber on the outside of an inner liner, before assembly and molding,
Electron beams are applied to the inner surface of the carcass sprue, which corresponds to both shoulder parts when molded as a pneumatic tire, and to the outer surface of the inner liner, which corresponds to both shoulder parts when molded as a pneumatic tire. By irradiating and providing an integrated pre-vulcanization zone inside the cord of the carcass ply, secondly, on the outside of the inner liner, the carcass ply, belt and tread rubber, with the rubber sheet pre-laminated on the inside, are sequentially applied. In a pneumatic tire configured by laminating, when the pneumatic tire is formed in the area of the rubber sheet that corresponds to both shoulder parts when the pneumatic tire is formed and on the outer surface side of the inner liner before assembly and molding. This problem can be solved by irradiating electron beams to the regions corresponding to both sides and parts of the carcass ply and providing an integrated pre-vulcanization area inside the cord of the carcass ply.

January First, before assembling and molding the tire, electron beams are irradiated on a predetermined area on the inner surface of the carcass ply, a predetermined area on the rubber sheet, and a predetermined area on the outer surface of the inner liner.
The inner liner, carcass ply and belt are subjected to the electron beam irradiation after pre-vulcanizing only the area;
A raw tire is assembled and molded by sequentially laminating tread rubber.

Here, since the areas irradiated with the electron beam are both areas corresponding to the shoulder part of the tire, these areas are overlapped and integrated by one assembly molding, and a thick pre-vulcanized area is formed. Pneumatic tires are manufactured by vulcanizing such raw tires, and the integrated pre-vulcanization region is located inside the cords of the carcass ply and forms a hard and thick band-like layer. Therefore, even if the cord of the carcass ply in the shoulder portion attempts to displace toward the inner surface of the tire during vulcanization, such displacement is strongly prevented by the thick pre-vulcanization region. As a result, the cord of the carcass ply is reliably prevented from protruding from the inner surface of the tire or rising near the inner surface of the tire.

1 swing 1 Hereinafter, a first embodiment of the present invention will be described based on the drawings.

In Fig. 1.2, l is a pneumatic radial tire, and this pneumatic tire l has a carcass ply 2 having a toroidal meridian cross section. The carcass ply 2 is composed of a rubber 3 and a large number of cords 4 embedded in the rubber 3 and extending in the meridian direction, and both ends of the cord in the width direction are folded back to wrap around the bead 5 and filler 8, respectively. An inner liner 7 made of rubber is placed inside the carcass ply 2 in the radial direction, while two belts 8 are placed outside the carcass ply 2 in the radial direction. This belt 8 is made of rubber and cords like the carcass ply 2, but the cords extend approximately parallel to the equatorial plane 9. Furthermore, tread rubber 10 is arranged on the outside of the belt 8 in the radial direction. The pneumatic tire 1 has a pair of shoulder parts 13 at the connection part between the tread part 11 and the sidewall part 12, and on the inner surface side of the carcass ply 2 in each shoulder part 13, there is an irradiation area 14 that has been irradiated with an electron beam. exists. On the other hand, also on the outer surface side of the inner liner 7 facing the irradiation area 14, that is, on the outer surface side of the inner liner 7 in the shoulder portion 13,
There is an irradiation area 15 that has been irradiated with an electron beam. The above-mentioned irradiation area 14.15 is the carcass ply.
2. By stacking and assembling the inner liners 7, they overlap each other and are integrated, forming a pre-vulcanization area 16 located inside the cords 4 of the carcass ply 2.

Next, in order to manufacture the pneumatic tire l as described above, first, the inner liner 7 is pasted on the tire forming drum, but this pasting is done beforehand, as shown in FIG.
An irradiation area 15 that is pre-vulcanized by irradiating an electron beam on an area corresponding to both shoulder parts 13 when formed as a pneumatic tire 1 on the outer surface side of the inner liner 7
Next, a carcass ply 2 is pasted and laminated on the outside of the inner liner 7, but the carcass ply 2 has also been pasted before, as shown in FIG. On both shoulder parts 13 when molded as a pneumatic tire on the inner surface side - The corresponding areas are irradiated with an electron beam to form irradiation areas 14 that have been pre-vulcanized. The irradiation areas 15 and 14 overlap and integrate over the entire surface when the inner liner 7 and carcass ply 2 are assembled and molded, and a pre-vulcanized area 1B having a total thickness of the irradiation areas 15 and 14 is formed as a part of the carcass ply 2. Formed inside cord 4.

In this way, since electron beam irradiation is performed only on a part of the necessary area, it is possible to reduce at least either the voltage applied when generating the electron beam or the irradiation dose. As a result, the equipment for electron beam irradiation can be small, and equipment costs and running costs can be reduced.
Both widthwise ends of the carcass ply 2 are folded back to wrap around the beads 5 and filler 8 to form a green case. On the other hand, the belt 8 and tread rubber lO are sequentially pasted on another molding drum to form a belt-tread assembly.Next, after deforming the green case into a toroidal shape, the belt 8 is attached to the outside of the green case.・After the tread assembly is transported, they are combined and pressed together to form a green tire. The green tire thus formed is first placed in a vulcanization mold and vulcanized. During this vulcanization, the green tire expands and deforms outward due to the internal pressure of the vulcanizing heating medium, but the amount of expansion and deformation is greatest at both shoulder portions 13 and is extremely small at other portions. Here, since the rubber 3 of the carcass ply 2 and the inner liner 7 are unvulcanized, they follow the expansion and deformation and flow outward.
Since cord 4 of carcass ply 2 can hardly be stretched and deformed, as a result, cord 4 is left behind due to expansion and deformation, and as a result, cord 4 is connected to rubber 3 of carcass ply 2 and inner liner? The inside of the pneumatic tire l tries to be displaced toward the inside surface. However, in this embodiment, a pre-vulcanization area 18 is provided inside the cord 4 of the carcass ply 2 in both shoulder parts 13 having the largest amount of expansion deformation.
Forming a hard band-like layer inside the cord 4 in 3,
Displacement of the cord 4 is prevented. Here, since the thickness of the pre-vulcanization area 1B is the sum of the thicknesses of the irradiation areas 14.15, only one layer of the carcass ply 2 or the inner liner 7 is irradiated with the electron beam and pre-vulcanized. Compared to the case of sulfurization, the thickness is approximately twice as high, and the above-mentioned blocking effect becomes stronger. As a result.

The distance from the cord 4 to the inner surface of the pneumatic tire l (lower cord gauge) does not become extremely thin at the shoulder portion 13, nor does the cord 4 protrude from the inner surface of the pneumatic tire 1.

FIG. 5 is a diagram showing a second embodiment of the invention. In this embodiment, a rubber sheet 21 such as a squeegee is laminated in advance on the inner surface of the carcass ply 2 before being attached to the tire forming drum, and then a pneumatic tire 1 is formed from this rubber sheet 21. The area corresponding to both shoulder parts 13 is irradiated with an electron beam to form a pre-vulcanized irradiation area 22. Next, a laminate of such a carcass ply 2 and a rubber sheath 21 is used to form a pre-vulcanized irradiation area 22. The green case is assembled and molded according to the procedure described above. At this stage, the irradiation area 22 and the irradiation area 15 are integrated to form a pre-vulcanized area inside the cord 4 of the carcass ply 2. Note that the other configurations and operations are similar to those of the first embodiment described above.

Next, a test example will be explained. For this test, two types of comparative tires 1.2 and a test tire to which the present invention was applied were prepared. Here, the comparison tire 1 is a tire using a carcass ply in which no area is irradiated with an electron beam, and the comparison tire 2 is a tire that uses a carcass ply in which no area is irradiated with an electron beam, and the comparison tire 2 is a tire with a 300 kilovolt electron beam irradiated on the inner side of the shoulder portion of each tire. This tire uses a carcass ply that is irradiated only with mega-metal. Furthermore, the test tire was formed by irradiating the inner surface of the carcass ply in both shoulder parts and the outer surface of the inner liner in both shoulder parts with a 300 kilovolt electron beam of 5 megarads each, and using these carcass plies and inner liner. It is a tire that has Each of these tires was cut after vulcanization, and the distance from the cord of the carcass ply to the inner surface of the tire (gauge below the cord) was measured using a measuring microscope. The results showed that in comparative tire 1, the cord protruded from the inner surface of the tire, and the distance was 0 layer m. Here, the distance Os+m of the comparative tire l is expressed as an index 1
00, the measurement result of comparative tire 2 is 1 in index display.
30, and 145 for the test tire. From this, it can be seen that in the test tire, the thickness of the pre-vulcanized region is thick, so that the displacement of the cord is strongly prevented.

As explained above, according to the present invention, it is possible to strongly prevent the cord of the carcass ply from being displaced during vulcanization, thereby improving the quality of the product (tire).

[Brief explanation of the drawing]

FIG. 1 is a meridian sectional view showing a first embodiment of the invention, and FIG. 2 is an enlarged sectional view of section A in FIG. Figure 3 is a sectional view showing the inner liner before assembly and molding;
FIG. 4 is a sectional view showing a carcass ply before assembly and molding, and FIG. 5 is a sectional view of a laminate of a carcass ply and a rubber sheet before assembly and molding, showing a second embodiment of the invention. l...Pneumatic tire 2...Carcass ply 4.
・Code 7・・・Inner liner death・
・Belt 10...Tread rubber 13...
Shoulder part 1B... Pre-vulcanization area 2! ...Rubber sheet patent applicant Brideston Co., Ltd. Agent Patent attorney Tadashi 1) Toshio Figure 2 1 4... Code 16... Pre-vulcanization area 4 Drawing 5 Figure 21... Rubber sheet 1 to

Claims (2)

[Claims] (1) In a pneumatic tire constructed by sequentially laminating carcass ply, belt, and tread rubber on the outside of an inner liner, both shoulders are formed on the inner side of the carcass ply before assembly and molding as a pneumatic tire. The pre-vulcanized area integrated inside the cord of the carcass ply is irradiated with an electron beam to the area corresponding to the inner liner and the area corresponding to both shoulders when molded as a pneumatic tire on the outer surface side of the inner liner. A pneumatic tire characterized by: (2) In a pneumatic tire constructed by sequentially laminating a carcass ply, a belt, and tread rubber on the outside of an inner liner with a rubber sheet pre-laminated on the inside, the rubber sheet is used as a pneumatic tire before assembly and molding. An electron beam is irradiated on the area that corresponds to both shoulders when molded and on the outer surface side of the inner liner that corresponds to both shoulders when molded as a pneumatic tire, and the area is integrated inside the cord of the carcass ply. A pneumatic tire characterized by having a pre-vulcanized area.