JP4052366B2 - Vulcanizing bladder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, the unvulcanized air-filled tire vulcanization bladder used to vulcanize molding (hereinafter, referred to as the bladder) it relates.
[0002]
[Prior art]
As shown in FIG. 13, vulcanization molding of a pneumatic tire is performed by placing an unvulcanized tire 30 in heated dies 31 a and 31 b and a bladder made of an elastic hollow body that can expand inside the unvulcanized tire 30. 1 is inserted, and high temperature and high pressure steam is blown into the bladder 1 to expand the bladder 1 and press the unvulcanized tire against the inner walls of the molds 31a and 31b and heat it for a predetermined time. .
[0003]
When the bladder 1 is inflated at the initial stage of vulcanization as described above, if air is trapped between the bladder 1 and the tire 30, a tire failure due to an air pocket occurs, so that the bladder is easily discharged. A large number of parallel or radial grooves extending mainly in the radial direction are provided on the outer surface of the film, or a large number of protrusions are provided by providing a large number of grooves in a direction intersecting with these grooves.
However, the above-described bladder provided with a large number of grooves may cause the following vulcanization failure to the tire during the vulcanization molding process.
[0004]
In particular, in the case of a bladder provided with a large number of block-shaped protrusions, when shrinkage is released from the pneumatic tire after completion of vulcanization, the rear wall surface of the groove in the bladder shrinkage direction scratches the inner surface of the vulcanized tire. create. In particular, when the inner surface layer of the tire is a thin inner liner layer, the effect of this scratch is great, and problems such as a reduction in the internal pressure holding force of the tire occur.
[0005]
In particular, when the inner liner layer is composed of a thermoplastic resin composition having a thickness of less than 1 mm, the resin is in a molten or softened state at the end of vulcanization when the melting point is lower than the vulcanization temperature. Therefore, scratches due to the wall surface behind the groove in the shrinkage direction of the groove are more likely to occur, and the problem is more serious.
[0006]
On the other hand, in the case of a bladder provided with a large number of grooves, there is a problem that the arrangement of the carcass cords in the region from the maximum tire width to the tread is disturbed in the case of a pneumatic radial tire. That is, since the behavior of the bladder expands in the process of expanding the bladder, this behavior acts on the arrangement of the carcass cords and causes disturbance.
[0007]
As a countermeasure against such a problem, it is better to incline the groove with respect to the tire shrinkage direction. However, if the incline is inclined in this way, the same as the bladder provided with a number of block-like convex portions described above in the bead portion region. There is a dilemma of creating scratches.
[0009]
[Problems to be solved by the invention]
Purpose is the present invention, when vulcanizing the pneumatic tire with the bladder having a plurality of grooves on the bladder surface, pressurized to prevent disturbance of the arrangement of the carcass cords without causing scratches on the bead portion inner surface vulcanization To provide a bladder.
[0014]
This onset Ming vulcanization bladder to achieve the above object, an unvulcanized tire by expanding inside of the unvulcanized tire to a vulcanization bladder for pressing the inner wall of the mold, the groove depth on the surface thereof A plurality of grooves of 0.1 to 2.0 mm are provided, and a groove corresponding to a bead part from a bead core part of the unvulcanized tire to a bead filler upper end part is substantially in the same direction as a contraction direction of the bladder; and The angle formed with the direction of the carcass cord of the groove at a portion corresponding to a portion other than the bead portion is 5 degrees or more.
[0015]
In the present invention, in the groove on the bladder surface, the region corresponding to the bead portion is substantially the same as the shrinkage direction of the bladder so that the inner surface of the tire does not get caught when the bladder shrinks. I will not let you. Further, since the grooves in the region other than the bead portion intersect with the carcass cord at an angle of 5 degrees or more, the arrangement of the carcass cord based on the groove can be prevented during the bladder expansion.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are reference views related to the present invention , and are perspective views showing original shapes of bladders of the first reference technique and the second reference technique .
[0017]
FIG. 1 shows an example in which a plurality of grooves 4 are formed on the surface, and FIG. 2 shows an example in which block-shaped convex portions 3 partitioned by a plurality of grooves are formed. 1 and 2, the vulcanizing bladder 1 has flange portions 2 and 2 at both ends. In FIG. 1, a plurality of grooves 4 are inclined substantially in parallel from one flange portion 2 to the other flange portion. Provided. In FIG. 2, a plurality of block-like convex portions 3 are provided over almost the entire outer surface. These convex portions 3 are formed in a grid pattern on the outer surface of the bladder 1 by intersecting a plurality of grooves 4 extending in the radial direction (the direction extending between both flange portions 2 and 2) and the circumferential direction. The shape of the convex part 3 is not necessarily limited to a quadrangle, and may be a hexagonal shape (tortoise shape) shown in FIG. 9, a circular shape shown in FIG. 10, or another shape.
[0018]
As shown in FIG. 13, the bladder 1 is inserted into the unvulcanized tire 30 with the flange portion 2 fixed to the inner diameter portion 33 of the mold for vulcanization molding of a pneumatic tire. used. At the time of vulcanization molding, high-temperature and high-pressure steam is supplied to the inside of the bladder 1 to expand it, and the unvulcanized tire 30 is pressed against the inner surface of the mold. After the vulcanization is completed, the steam is exhausted from the bladder 1 to be contracted and detached from the vulcanized tire.
[0019]
As described above, when the bladder 1 expands and contracts, its wall surface moves toward the flanges 2 and 2 on both sides as indicated by the arrows when contracting with the equator line M as a boundary, and in the opposite direction when expanded. Moving. (See Figs. 1 and 2)
The first reference technique describes a part of the preferred embodiment of the present invention, and the XX section in FIGS. 1 and 2 is configured as shown in FIGS. . 3 shows a cross section taken along line XX in FIG. 1 and FIG. 4 shows a cross section in FIG. The groove depth of the groove 4 is 0.1 to 2.0 mm, preferably 0.1 to 0.7 mm, and a draft angle 7 is provided on the groove wall 5 on the rear side of the bladder orientation (arrow) of the groove 4. ing. The draft angle 7 is formed so that the angle with respect to the direction perpendicular to the plane direction of the bladder is preferably 15 to 75 degrees , more preferably 45 to 60 degrees , during vulcanization. If the groove depth is less than 0.1 mm, the effect of exhausting air at the time of bladder expansion is not sufficient, and tire inner surface failure due to air accumulation tends to occur. Further, if it exceeds 2.0 mm, even if a draft is provided, the inner surface of the tire is easily scratched when the bladder contracts.
[0020]
If the draft angle 7 of the groove 4 is less than 15 degrees, it cannot sufficiently slide with the tire inner wall surface in a heated state, which may cause scratches. Further, if the draft exceeds 75 degrees, the space for exhausting the air when the bladder is expanded becomes narrow, and the tire inner surface is liable to be damaged due to air accumulation.
[0021]
Draft also vulcanization is bladder expands, the slope when the unvulcanized tire is pressed against the inner wall of the mold, the groove at an angle of the same gradient vulcanized pneumatic tire surface Since it is transferred as a corresponding convex portion, the gradient can be measured from a pneumatic tire .
[0022]
Of course, the draft angle may be provided on the groove wall on the front side of the groove 4 in the bladder contraction direction. When draft angles are provided on both the front and rear sides, it is preferable that the draft angles on the front and rear sides are the same or the draft angle on the rear side is made larger.
[0023]
The second reference technique describes a part of the preferred embodiment of the present invention, and the XX cross sections in FIGS. 1 and 2 are configured as shown in FIGS. 5 and 6, respectively. ing. In the second reference technique , an arc-shaped chamfer 10 is provided at the edge of the groove 4 on the rear side in the bladder contraction direction (arrow). The curvature radius of the chamfer 10 during vulcanization is preferably 0.1 mm or more and 3 times or less of the groove depth. More preferably, it is 0.5-1.5 mm. The groove depth is 0.1 to 2.0 mm, preferably 0.1 to 0.7 mm, as in the first reference technique . If the radius of curvature is less than 0.1 mm, the pneumatic tire that is still heated immediately after vulcanization has a high frictional resistance when the bladder is detached, and may cause scratches. On the other hand, if the radius of curvature exceeds three times the groove depth, the space for exhausting air when the bladder expands becomes narrow, and air cannot be exhausted sufficiently.
[0024]
Further, since the arc-shaped chamfer is transferred to the pneumatic tire side in the same manner as described above, the radius of curvature can be obtained from the pneumatic tire .
[0025]
The chamfer 10 may also be provided at the front edge of the groove 4 in the bladder contraction direction, as shown in FIGS. 7 and 8, which are other examples of the XX cross-sectional views of FIGS. When chamfering is provided on both the front and rear sides, it is preferable that the front and rear side chamfers have the same size or the rear side chamfer is made larger.
[0026]
9 and 10 show examples of block-shaped convex portions divided by a large number of grooves, FIG. 9 shows a hexagonal shape (tortoise shape), and FIG. 10 shows a circular example. The diameter L of the block is preferably 3 to 10 mm, but is not limited to the range as long as the air discharge effect (air bleeding property) at the time of bladder expansion can be secured. Further, the shape of the block-shaped convex portion is not limited to a hexagon or a circle.
[0027]
Figure 11 is a perspective view showing a prototype of the onset Ming bladder.
In FIG. 11, flange portions 2 and 2 are provided at both ends of the bladder 1, and a plurality of grooves 4 are provided on the outer surface from one flange portion 2 to the other flange portion 2.
In the groove 16, the direction of the groove 4 is substantially the same as the tire shrinkage direction in the portion 16 corresponding to the bead portion from the bead core portion of the tire to the top of the bead filler, but in the portion 15 other than the corresponding portion 16 of the bead portion, As shown in FIG. 12, it intersects with the carcass cord 17 inside the tire at an angle of 5 ° or more. Therefore, the portion 16 corresponding to the tire bead portion and the portion of the groove 4 corresponding to the portion 15 other than the bead portion are bent at the boundary.
[0028]
In this way, in the portion 16 corresponding to the bead portion, the direction of the groove 4 is substantially parallel to the shrinkage direction of the bladder, so there is no risk of scratching the inner surface of the tire when the bladder shrinks. Is preferably 15 degrees or less with respect to the bladder contraction direction.
[0029]
The groove in the portion 15 corresponding to the range other than the bead portion should be provided so as to intersect the carcass cord of the tire at an angle of 5 degrees or more, preferably 15 degrees or more. If it is less than 5 degrees, the behavior of the expansion of the groove spacing in the process of expansion of the bladder at the start of vulcanization causes disturbance in the arrangement of the carcass cords in the region from the maximum tire width to the tread, resulting in tire durability. Because it gets worse.
[0030]
The groove angle may be set as described above, and a draft or chamfer may be provided in the groove as in the first and second reference techniques .
Further, the present invention is effective when a thermoplastic resin that is easily softened during vulcanization is used on the inner surface of the pneumatic tire for the purpose of preventing gas permeation.
[0031]
As a thermoplastic resin composition used for this invention, the following thermoplastic resins or arbitrary resin mixtures containing these can be mentioned, for example.
[0032]
Polyolefin resin (for example, high density polyethylene (HDPE), low density polyethylene (LDPE), ultra high molecular weight polyethylene (UHMWPE), isotactic polypropylene, ethylene propylene copolymer resin), polyamide resin (for example, nylon 6 (N6)) Nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 666 (N666), nylon 610 (N610), nylon 612 (N612), nylon 6/66/610 Polymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer), polyester resin (for example, poly Butylene terephthalate (PB ), Polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polyester copolymer, PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimidic acid / Aromatic polyester such as polybutyrate terephthalate copolymer), polyether resin (for example, polyacetal (POM), polyphenylene oxide (PPO), polysulfone (PSF), polyether ether ketone (PEEK), polynitrile resin (for example, polyacetal) Acrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer ), Polymethacrylate resins (for example, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl resins (for example, vinyl acetate (EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH)), Polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl methacrylate copolymer), cellulosic resins (eg, cellulose acetate, cellulose acetate butyrate), fluorine resins ( For example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE), imide resin (for example, aromatic polyimide (PI)), polyaceter And the like.
[0033]
The thermoplastic resin composition may be a thermoplastic elastomer composition in which the continuous phase is a thermoplastic resin and the dispersed phase is an dynamically crosslinked elastomer. As an elastomer component in the elastomer composition constituting the thermoplastic elastomer composition, for example, the following elastomer and any mixture containing them as a main component can be used.
[0034]
Diene rubber and hydrogenated products thereof (for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubber (for example, ethylene propylene) Rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer), halogen-containing rubber (for example, Br- IIR, Cl-IIR, bromide of isobutylene paramethylene copolymer (Br-IPMS), CR, hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid modified chlorinated polyethylene ( M-CM), silicone rubber (for example, methyl vinyl silicone) Rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg polysulfide rubber), fluorine rubber (eg vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone) Examples thereof include rubber, fluorine-containing phosphazene rubber, urethane rubber, epichlorohydrin rubber, thermoplastic elastomer (for example, styrene elastomer, olefin elastomer, ester elastomer, urethane elastomer, polyamide elastomer).
[0035]
The ratio of the thermoplastic resin composition and the elastomer composition constituting the thermoplastic elastomer composition used in the present invention is not particularly limited, but preferably the thermoplastic resin composition / elastomer composition = 85 / weight ratio. 15 to 15/85. In this thermoplastic elastomer composition, the elastomer is dynamically cross-linked. That is, the thermoplastic resin and the elastomer are kneaded but the elastomer is allowed to crosslink. By using such a production method, the obtained thermoplastic elastomer composition is in a state in which a crosslinked elastomer phase that becomes a discontinuous phase is finely dispersed in a thermoplastic resin that becomes a continuous phase.
[0036]
Although the embodiment described above has been described for the case of a pneumatic tire, the first reference technique and the second reference technique can be applied to vulcanization of, for example, a bellows type air spring, a fender, an air roll, and the like. can do.
[0037]
【Example】
( Reference Examples 1-11, Comparative Examples 1-5, Conventional Example 1)
In vulcanizing and molding a pneumatic radial tire having a tire size of 185 / 65R14 and an inner liner (innermost layer) of nylon 11 having a thickness of 0.1 mm (melting point: about 190 ° C.) at 180 ° C. for 10 minutes, As the vulcanizing bladder, the convex shape of the surface of the structure shown in FIGS. 2 and 4 and FIGS. 2 and 6 is a square shape (7 mm square, block interval 3 mm), and a hexagonal shell shape ( The convex portion width L (distance between opposite sides) 20 mm: groove width 7 mm) and the circular shape shown in FIG. 10 (convex portion diameter 10 mm, circle center distance 17 mm), draft angle and chamfer radius are shown in Table 1. Vulcanization was performed using differently made bladders. Table 1 shows the presence / absence of failure of the inner surface of the tire due to rubbing at the time of removal of the bladder during vulcanization molding as x (present) and ◯ (absent).
[0038]
[Table 1]
[0039]
(Examples 1-4 , Comparative Examples 6-8, Conventional Example 2)
A radial tire having the same structure as in Reference Example 1 and a tire having a half radial structure in which the carcass cord direction is set to 8 degrees have the bladder groove shown in FIG. 12 under the same vulcanization conditions, and the angles of the parallel grooves are as shown in Table 2. Vulcanization molding was performed differently.
The following tire durability test was performed as an influence of the inner surface failure of the tire due to rubbing at the time of detachment of the bladder at the time of vulcanization molding and carcass disturbance at the time of bladder expansion. The results are shown in Table 2.
[0040]
Tire endurance test: Applying a pressure of 240MPa to the tire and a load of 7.79kN, running at 20,000km on a drum with a diameter of 1707mm at a speed of 80km / h, observing the appearance of the tire and the state of the inside (inner liner part) did.
○: No abnormality Δ: The appearance of the liner was whitened due to stress strain at the disordered portion of the carcass cord arrangement on the liner surface, but there was no practical problem.
X: Liner cracks occurred in the carcass cord disordered part on the liner surface.
[0041]
[Table 2]
[0042]
【The invention's effect】
As described above, the first reference technique and the second reference technique that are suitably added to the present invention are the drafts in the groove wall on the rear side in the contraction direction of the bladder in the bladder having grooves on the outer surface. Alternatively, an arc-shaped chamfer is provided, the draft angle during vulcanization is 15 to 75 degrees with respect to the direction perpendicular to the bladder surface direction, and the arc-shaped chamfer has a radius of curvature of 0.1 mm or more during vulcanization and a groove depth. Therefore, scratches on the inner surface of the pneumatic tire due to rubbing when the bladder is detached after the tire vulcanization can be prevented.
[0043]
According to the present invention , in a bladder provided with a plurality of grooves on the surface, a groove corresponding to a bead portion of an unvulcanized tire has a groove substantially in the same direction as the bladder contraction direction, and a groove corresponding to a portion other than the bead portion corresponds to a tire carcass. Since it is provided in a direction that intersects with the cord at an angle of 5 degrees or more, it can prevent disorder of the arrangement of the tire carcass cord when the bladder expands during tire vulcanization, and also prevents scratches on the inner surface of the tire when the bladder contracts it can.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a bladder according to an embodiment of a reference technique of the present invention.
2 is a perspective view of a bladder made of an embodiment of another reference technology of the present invention.
FIG. 3 is a partially enlarged cross-sectional view showing a cross section taken along line XX in FIG. 1;
4 is a partially enlarged cross-sectional view showing a XX cross section of FIG. 2;
FIG. 5 is a partial enlarged cross-sectional view showing another embodiment of the reference technique corresponding to FIG. 3;
FIG. 6 is a partially enlarged cross-sectional view showing an embodiment of another reference technique corresponding to FIG. 4;
7 is a partially enlarged cross-sectional view showing an embodiment of still another reference technique corresponding to FIG. 3. FIG.
FIG. 8 is a partially enlarged cross-sectional view showing still another embodiment of the reference technique corresponding to FIG. 4;
FIG. 9 is a plan view showing the main part of the surface of a bladder according to another embodiment of the reference technique of the present invention.
FIG. 10 is a plan view showing the main part of the surface of a bladder according to still another embodiment of the reference technique of the present invention.
11 is a perspective view of a bladder showing the implementation of the invention.
12 is an explanatory diagram showing the relationship between blanking ladder groove direction and the carcass direction of the pneumatic tire of the present invention.
FIG. 13 is an explanatory view showing a main part of a mold for vulcanizing a pneumatic tire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vulcanizer for vulcanization 3 Block-shaped convex part 4 Groove 7 Draft 10 Chamfer 15 Part corresponding to other than bead part 16 Part corresponding to bead part 30 Pneumatic tire

Claims (5)

A vulcanizing bladder that presses the unvulcanized tire against the inner wall of the mold by expanding inside the unvulcanized tire, and a plurality of grooves having a groove depth of 0.1 to 2.0 mm are provided on the surface thereof, The groove of the portion corresponding to the bead portion from the bead core portion of the unvulcanized tire to the upper end portion of the bead filler is made substantially the same direction as the shrinkage direction of the bladder, and the groove of the portion corresponding to a portion other than the bead portion is formed. Vulcanizing bladder with an angle of 5 degrees or more with the direction of the carcass cord. A radius of curvature of 0.1 mm at a draft angle of 15 to 75 degrees with respect to a direction perpendicular to the surface direction of the bladder, or a groove wall at least on the rear side in the contraction direction of the bladder of the plurality of grooves. above, vulcanization bladder of claim 1 comprising providing a 3-fold less arcuate chamfer of the groove depth. Vulcanization bladder of claim 1 or 2 to an angle with respect to the bladder contraction Direction of the grooves of the portion corresponding to the bead portions below 15 degrees. The vulcanization bladder according to claim 1 , 2 or 3 , wherein an inner surface of the unvulcanized tire is a layer of a thermoplastic resin composition. A pneumatic tire vulcanized using the vulcanizing bladder according to claim 1 , 2 , 3 or 4 .