Patent Publication Number: US-2020282679-A1

Title: Pneumatic Tire and Method for Manufacturing the Same

Description:
TECHNICAL FIELD 
     The present technology relates to a pneumatic tire and a method for manufacturing the same and particularly relates to a pneumatic tire and a method for manufacturing the same that can provide improved productivity when applying a sound absorbing member or a sealant layer to a tire inner surface. 
     BACKGROUND ART 
     In general, the outer surface of a bladder, which is used when vulcanizing a green tire, is formed with a plurality of exhaust grooves (recesses) extending in the radial direction. These grooves are provided to evacuate air between the tire inner surface and the bladder to the outside (see, for example, Japan Unexamined Patent Publication No. 2014-84007). As a result, a plurality of protrusions that correspond to the recesses in the outer surface of the bladder are formed on the inner surface of a vulcanized pneumatic tire. 
     Since the tire inner surface does not include any marks to indicate the appropriate position at which to apply a sound absorbing member or a sealant layer, applying the sound absorbing member or the sealant layer to the inner surface of such a vulcanized pneumatic tire requires much time and effort, thereby lowering productivity. 
     SUMMARY 
     The present technology provides a pneumatic tire and a method for manufacturing the same that can provide improved productivity when applying a sound absorbing member or a sealant layer to a tire inner surface. 
     A pneumatic tire according to an embodiment of the present technology includes an indicator made of a protrusion portion or a recess portion extending in a circumferential direction on a tire surface and a sound absorbing member or a sealant layer applied to the tire inner surface along the indicator. 
     A method for manufacturing a pneumatic tire according to an embodiment of the present technology includes the steps of: vulcanizing a green tire using a bladder having a bladder outer surface formed with a recess portion or a protrusion portion extending in a bladder circumferential direction; forming an indicator made of a protrusion portion or a recess portion extending in a tire circumferential direction on an inner surface of the vulcanized pneumatic tire; and applying a sound absorbing member or a sealant layer to the inner surface of the pneumatic tire along the indicator. 
     In the present technology, a tire inner surface is formed with an indicator made of a protrusion portion or a recess portion extending in a tire circumferential direction, and a sound absorbing member or a sealant layer is applied to a tire inner surface along the indicator. Thus, the sound absorbing member or the sealant layer can be accurately and efficiently applied. With this configuration, in a pneumatic tire in which a sound absorbing member or a sealant layer is applied to the tire inner surface, productivity can be improved. 
     In the present technology, an angle of the indicator with respect to the tire circumferential direction is preferably from 0° to 10°. With this configuration, the indicator is continuously formed on the tire inner surface in the tire circumferential direction. 
     In the present technology, the protrusion portion or the recess portion constituting the indicator preferably has a height or depth of from 0.3 mm to 2.0 mm and a width of from 0.5 mm to 5.0 mm. With this configuration, the dimensions of the protrusion portion or the recess portion constituting the indicator can be appropriately set to prevent air permeability of an inner liner layer from deteriorating. 
     In the present technology, preferably at least one section of the indicator in the tire circumferential direction includes a missing portion. With this configuration, for example, the missing portion can be used as a start position for applying the sound absorbing member, and the sound absorbing member or the sealant layer can be applied even more efficiently. 
     In the present technology, preferably at least two of the indicators are formed on the inner surface of the pneumatic tire. With this configuration, the same bladder can be used to apply sound absorbing members or sealant layers in a plurality of sizes. 
     In the present technology, the indicator is preferably expressed as a marking for identification made of a letter, a number, a symbol or a graphic. As a result, in a configuration where a plurality of the indicators are formed on the tire inner surface, for example, the sound absorbing member or the sealant layer can be accurately applied. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective cross-sectional view of a pneumatic tire according to an embodiment of the present technology. 
         FIGS. 2A and 2B  are enlarged views of the X portion in  FIG. 1  and cross-sectional views taken along a plane orthogonal to the extension direction of an indicator, where  FIG. 2A  illustrates a case where the indicator is a protrusion portion and  FIG. 2B  illustrates a case where the indicator is a recess portion. 
         FIG. 3  is a perspective cross-sectional view of a modification example of a pneumatic tire according to an embodiment of the present technology. 
         FIG. 4  is a perspective view of a bladder used in a step of vulcanization molding for the pneumatic tire in  FIG. 1 . 
         FIGS. 5A and 5B  are enlarged views of the Y portion in  FIG. 4  and cross-sectional views taken along a plane orthogonal to the extension direction of a recess portion or a protrusion portion formed on a bladder outer surface, where  FIG. 5A  illustrates the recess portion and  FIG. 5B  illustrates the protrusion portion. 
         FIG. 6  is a perspective cross-sectional view of another modification example of a pneumatic tire according to an embodiment of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     Configurations of embodiments of the present technology will be described in detail below with reference to the accompanying drawings.  FIG. 1  illustrates a pneumatic tire according to an embodiment of the present technology. In  FIG. 1 , the pneumatic tire according to the present embodiment includes an annular tread portion  1  extending in the tire circumferential direction, a pair of sidewall portions  2  disposed on either side of the tread portion  1 , and a pair of bead portions  3  disposed inward of the sidewall portions  2  in the tire radial direction. An inner liner layer (not shown) is disposed on a tire inner surface  4 . 
     In the pneumatic tire described above, a sound absorbing member  5  is applied to a region of the tire inner surface  4  corresponding to the tread portion  1  along the tire circumferential direction. The sound absorbing member  5  can be bonded to the tire inner surface  4  using an adhesive or double-sided adhesive tape. The sound absorbing member  5  is made of a porous material with open cells and has predetermined noise absorbing properties based on the porous structure. Polyurethane foam is preferably used as the porous material of the sound absorbing member  5 . 
     As illustrated in  FIGS. 1, 2A and 2B , an indicator  10  made of a protrusion portion  10   a  or a recess portion  10   b  extending in the tire circumferential direction is formed on the tire inner surface  4 . The indicator  10  is a mark for indicating the appropriate position at which to apply the sound absorbing member  5 . As illustrated in  FIG. 2A , the protrusion portion  10   a  constituting the indicator  10  protrudes inward in the tire radial direction, and as illustrated in  FIG. 2B , the recess portion  10   b  constituting the indicator  10  is recessed outward in the tire radial direction. The protrusion portion  10   a  or the recess portion  10   b  is formed by pressing the tire inner surface  4  with a bladder B (described later). The sound absorbing member  5  is applied along the protrusion portion  10   a  or the recess portion  10   b  formed in this manner. 
     In the pneumatic tire described above, the indicator  10  made of the protrusion portion  10   a  or the recess portion  10   b  extending in the tire circumferential direction is formed on the tire inner surface  4 , and the sound absorbing member  5  is applied to the tire inner surface  4  along the indicator  10 . Thus, the sound absorbing member  5  can be applied accurately and efficiently. As a result, in a pneumatic tire in which the sound absorbing member  5  is applied to the tire inner surface  4 , productivity can be improved. 
     In the pneumatic tire described above, the angle of the indicator  10  with respect to the tire circumferential direction is preferably from 0° to 10°. By appropriately setting the angle of the indicator  10  with respect to the tire circumferential direction within the range described above, the indicator  10  is continuously formed in the tire circumferential direction on the tire inner surface  4 . Hence, the indicator  10  does not stop at a midway position on the tire circumference. Note that in the embodiment illustrated in  FIG. 1 , the angle of the indicator  10  with respect to the tire circumferential direction is 0°. 
     In the protrusion portion  10   a  or the recess portion  10   b  constituting the indicator  10 , a height h of the protrusion portion  10   a  or a depth d of the recess portion  10   b  is preferably from 0.3 mm to 2.0 mm, and a width w of the protrusion portion  10   a  or the recess portion  10   b  is preferably from 0.5 mm to 5.0 mm. By appropriately setting the dimensions of the protrusion portion  10   a  or the recess portion  10   b  constituting the indicator  10  within the ranges described above, it is possible to prevent deterioration in the air permeability of the inner liner layer disposed on the tire inner surface  4 . In a configuration where the recess portion  10   b  is formed, if the depth d of the recess portion  10   b  exceeds 2.0 mm, the thickness of the inner liner layer cannot be sufficiently ensured, and it becomes more difficult to prevent the air permeability of the inner liner layer from deteriorating. 
       FIG. 3  illustrates a modification example of a pneumatic tire according to an embodiment of the present technology. In  FIG. 3 , at least one section of the indicator  10  in the tire circumferential direction includes a missing portion  11 . The missing portion  11  is a portion where the protrusion portion  10   a  or the recess portion  10   b  is not present on the tire circumference. By providing the missing portion  11 , for example, the missing portion  11  can be used as a start position for applying the sound absorbing member  5 , and thus the sound absorbing member  5  can be applied even more efficiently. 
     As illustrated in  FIG. 3 , at least two indicators  10  (four are illustrated in  FIG. 3 ) are formed on the tire inner surface  4 . By forming a plurality of the indicators  10  on the tire inner surface  4 , the same bladder B can be used to apply the sound absorbing members  5  in a plurality of different sizes. 
     Furthermore, as illustrated in  FIG. 3 , the indicator  10  is expressed as a marking  12  for identification made of a letter, a number, a symbol or a graphic. The embodiment illustrated in  FIG. 3  is an exemplary case where the marking  12  is one letter (letter of the alphabet) combined with one number and is located at the missing portion  11  of the indicator  10 . However, in a configuration where the missing portion  11  is not included, the marking  12  for identification may be positioned adjacent to the indicator  10 . By putting the marking  12  for identification onto the indicator  10 , in a configuration where the tire inner surface  4  includes the plurality of indicators  10 , for example, the sound absorbing member  5  can be accurately applied without confusing the indicators  10  with one another. More particularly, the marking  12  for identification is preferably formed as the recess portion  10   b  in the tire inner surface  4 . 
     Next, a method for manufacturing a pneumatic tire according to an embodiment of the present technology will be described. As illustrated in  FIGS. 4, 5A and 5B , in the method for manufacturing a pneumatic tire according to an embodiment of the present technology, a green tire is vulcanized using the bladder B having a bladder outer surface  21  formed with a recess portion  20   a  or a protrusion portion  20   b  extending in the bladder circumferential direction. In the step of vulcanization molding, the inner surface of the tire is pressed by the bladder B to form the indicator  10  made of the protrusion portion  10   a  or the recess portion  10   b  extending in the tire circumferential direction on the inner surface of the vulcanized pneumatic tire. At this time, the protrusion portion  10   a  and the recess portion  10   b  formed on the tire inner surface  4  correspond to the recess portion  20   a  and the protrusion portion  20   b  formed on the bladder outer surface  21  illustrated in  FIGS. 5A and 5B , respectively. After molding the pneumatic tire in which the indicator  10  is formed on the tire inner surface  4 , the sound absorbing member  5  is applied to the tire inner surface  4  along the indicator  10 . 
     As a result, it is possible to obtain a pneumatic tire in which the sound absorbing member  5  is applied to the tire inner surface  4  along the indicator  10 . According to this method for manufacturing a pneumatic tire, the sound absorbing member  5  can be applied accurately and efficiently, and therefore productivity can be improved. 
     In the pneumatic tire described above, the indicator  10  is the protrusion portion  10   a  or the recess portion  10   b  extending in the tire circumferential direction, but the indicator  10  is not particularly limited as such. From the perspective of increasing tire productivity, the indicator  10  is preferably the protrusion portion  10   a . In the embodiment described above, a case in which the indicator  10  continuously extends in the tire circumferential direction at a portion excluding the missing portion  11  has been described. However, the indicator  10  may be, for example, a dashed line or dotted line that extends intermittently in the tire circumferential direction. 
     In the embodiment illustrated in  FIGS. 1 to 5 , a case has been described where the sound absorbing member  5  is applied to the tire inner surface  4 . However, the present technology can also be applied to a pneumatic tire in which a sealant layer  6  is applied to the tire inner surface  4  instead of the sound absorbing member  5 . More specifically, as illustrated in  FIG. 6 , the sealant layer  6  is bonded in the tire circumferential direction to a region of the tire inner surface  4  corresponding to the tread portion  1 . The sealant layer  6  is formed of an adhesive sealant material. Any adhesive composition can be used as the sealant material. By using such a sealant material, the sealant material can bond to the tire inner surface  4  because of the adhesive properties of the sealant material.