JP2006349641A - Deterioration testing method of tire component and deterioration testing device of tire component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deterioration testing method of a tire component obtaining data satisfactorily conformable to deterioration characteristics by actual use by setting heat (temperature), moisture (humidity) and oxygen (oxygen partial pressure) at the optimum values. <P>SOLUTION: In the deterioration testing method of a tire component, deterioration promotion treatment of the tire component 12 is performed while setting the internal pressure of a storage pressure vessel 14 in the range of 1.2-10 kg/cm<SP>2</SP>, the internal oxygen partial pressure of the pressure vessel 14 at least 20% or more, the temperature of the internal atmosphere of the pressure vessel 14 up to 100°C, and the humidity of the internal atmosphere of the pressure vessel 14 in the range of 70-100%RH. Accordingly, since the deterioration promotion treatment is performed in an atmosphere in which not only pressure, temperature and humidity but also oxygen are enriched, deterioration of the tire component 12 is promoted in a sufficiently promoted deteriorating environment close to that in an actual use in which deterioration factors are combined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tire constituent member deterioration test method and a tire constituent member deterioration test apparatus.

As a means for estimating in advance durability against deterioration when a tire is actually used, evaluation of the characteristics of tire constituent members that have been allowed to stand in a predetermined atmosphere and promote deterioration has been performed. For example, in Japanese Patent Laid-Open No. 4-293940, a sample in which a steel cord is embedded in vulcanized rubber is deteriorated in pressurized steam at 105 ° C. for 24 hours, and then the pulling force of the steel cord and the rubber coverage are disclosed. A steam aging adhesion test is disclosed that measures Japanese Patent Laid-Open No. 8-187799 discloses that a steel cord embedded in a vulcanized rubber is subjected to pressure cooker aging under conditions of a temperature of 130 ° C. and a humidity of 95% RH, and the steel cord pulling force An adhesion degradation evaluation test is disclosed in which the outer side is affirmed. Further, in JP-A-8-259740, a sample in which a steel cord is embedded in vulcanized rubber is left in a constant temperature and humidity chamber at a temperature of 50 ° C. and a humidity of 95% RH for 14 days, and the steel cord is pulled out. It is disclosed that water resistance adhesion is evaluated by measuring force, and a vulcanized rubber piece is left for 72 hours under a condition of a temperature of 70 ° C. and a pure oxygen pressure of 20 kgf / cm ² , and bent. A pressurized oxygen aging test for evaluating the presence or absence of cracks is disclosed.
JP-A-4-293940 JP-A-8-187799 JP-A-8-259740

  By the way, it is known that tire deterioration is greatly affected by heat, moisture, and oxidation and aging due to oxygen. The contribution of each varies depending on the weather conditions and road environment in which the tire is actually used, the type and location of the tire, and the internal pressure used.

  In the conventional deterioration test method, deterioration due to a part of the heat, moisture, and oxygen (only one person to two persons) is promoted. In some cases, a good correlation with the deterioration characteristics due to the use of the resin cannot be obtained, which is not always satisfactory.

  The present invention has been made to solve the above problems, and heat (temperature), moisture (humidity), oxygen (oxygen partial pressure) are set to optimum values, and correspondence with deterioration characteristics due to actual use. An object of the present invention is to provide a tire constituent member deterioration test method and a tire constituent member deterioration test apparatus capable of obtaining good data.

  The invention according to claim 1 evaluates the characteristics of the tire constituent member after the tire constituent member is left for a predetermined time in an atmosphere set to a predetermined pressure, temperature, and humidity and subjected to deterioration promotion treatment. A deterioration test method for a tire constituent member is characterized in that the deterioration promotion treatment is performed in an atmosphere containing oxygen of 70% RH or higher and a partial pressure of 20% or higher.

Next, a deterioration test method for a tire constituent member according to claim 1 will be described.
In the deterioration test method for a tire constituent member according to claim 1, the tire constituent member to be tested is subjected to a deterioration promoting treatment in an atmosphere containing oxygen of 70% humidity and 20% or higher in partial pressure, and then deteriorated. The characteristics of the tire constituent member subjected to the acceleration treatment are evaluated.

For example, when estimating deterioration characteristics in actual use of a tire, the pressure (oxygen partial pressure), temperature, and humidity in the deterioration promotion process are assumed for the tire use environment (weather conditions, road conditions, use internal pressure, etc.), and the tire. Set in consideration of the type.
For some members cut out from the tire and sample pieces simulating a tire constituent member, it is preferable to set conditions in consideration of the applied tire part.

In addition, a tire preliminary test may be performed to set conditions under which the destruction mode is the same as in actual use. Conversely, the degradation environment in actual use can be estimated by searching for degradation promotion conditions that cause the destruction mode to be the same as in actual use.
In this tire component deterioration test method, not only pressure, temperature, and humidity, but also an oxygen-enriched atmosphere is used to promote deterioration. Degradation can be promoted in a degraded environment that is promoted by

In conventional degradation promotion treatment, the pressure or temperature is increased to increase the degradation rate. However, there is a restriction in terms of equipment to increase the pressure, and thermal degradation occurs if the temperature is increased too much. Becomes dominant and it becomes a simple heat aging promotion test.
In the present invention, as the oxygen-enriched atmosphere, an atmosphere having an oxygen concentration higher than that of the atmosphere, that is, an oxygen containing 20% or more partial pressure is applied.

As described above, in the present invention, since the deterioration promotion by the oxygen-enriched atmosphere is used in the necessary high humidity environment, the deterioration in actual use is particularly important in the evaluation of the steel member and its peripheral members that are easily affected by moisture. Degradation can be efficiently promoted while reproducing the state.
When the humidity is less than 70% RH, for example, in a deterioration evaluation of a composite material called a tire, in particular, a steel belt ply member that is easily affected by moisture and its peripheral member evaluation, the deterioration state in actual use efficiently. May not be able to be reproduced.

  The invention according to claim 2 is characterized in that, in the method for accelerating deterioration of a tire constituent member according to claim 1, the test is performed in an atmosphere containing oxygen of 50% or more by partial pressure.

Next, a deterioration test method for a tire constituent member according to claim 2 will be described.
The deterioration can be efficiently promoted by performing the deterioration promoting process on the tire constituent member in an atmosphere containing 50% or more oxygen by partial pressure.

The invention according to claim 3 is the method of accelerating deterioration of a tire component according to claim 1 or 2, wherein the deterioration promotion treatment is performed at a pressure of 1.2 to 10 kg / cm ² and a temperature of 60 to 100 °. It is performed within the range of C.

Next, a deterioration test method for a tire constituent member according to claim 3 will be described.
When the pressure is less than 1.2 kg / cm ² , for example, even in a small passenger car tire, the environment is lower than the normal tire internal pressure, so that it does not meet the purpose of the accelerated test.

On the other hand, when the pressure exceeds 10 kg / cm ² , for example, in a large truck / bus tire, the acceleration is higher under a condition higher than the normal tire internal pressure, but it is not preferable for safety of the apparatus. For example, when further promotion is necessary, it can be dealt with by implementing countermeasures by increasing the oxygen partial pressure.

Further, if the temperature is less than 60 ° C., the acceleration effect of this deterioration test is reduced, which is not desirable. Depending on the tire type and usage environment, the tire temperature is 60 ° C. or higher even in actual normal continuous running.
On the other hand, when the temperature exceeds 100 ° C., only the deterioration of the rubber due to the heat alone greatly contributes, and the failure mode is changed from the actual one, which is out of the purpose of this test.
Therefore, it is preferable to perform the deterioration promoting treatment within a range of a pressure of 1.2 to 10 kg / cm ² and a temperature of 60 to 100 ° C.

  According to a fourth aspect of the present invention, in the tire component member deterioration acceleration test method according to any one of the first to third aspects, the tire component member is a vulcanized rubber, a vulcanized rubber, and a vulcanized rubber. An adhesive evaluation test between the vulcanized rubber and the steel cord is performed after the deterioration accelerating treatment.

Next, a tire component member deterioration test method according to claim 4 will be described.
In the tire component member deterioration test method according to the fourth aspect, the adhesion evaluation test of the tire component member including the vulcanized rubber and the steel cord whose deterioration is accelerated is performed.

  According to a fifth aspect of the present invention, in the method for accelerating deterioration of a tire constituent member according to any one of the first to fourth aspects, a fatigue test of the steel cord is performed after the deterioration accelerating treatment. It is characterized by.

Next, a deterioration test method for a tire constituent member according to claim 5 will be described.
In the tire component deterioration test method according to the fifth aspect, a fatigue test is performed on the steel cord taken out from the tire component whose deterioration has been accelerated.

  The deterioration promoting device for a tire constituent member according to claim 6 is a storage container for storing the tire constituent member, and a gas supply means capable of supplying a gas containing 20% or more of oxygen by partial pressure in the storage container. A humidifying means capable of setting the humidity in the storage container to 70% RH or more, a heating means capable of heating the atmosphere in the storage container, the gas supply means, the humidification means, and the heating means. Control means for controlling and controlling the temperature, humidity, and pressure in the container.

Next, the operation of the tire constituent member deterioration test apparatus according to claim 6 will be described.
In the tire constituent member deterioration test apparatus according to claim 6, the tire constituent member as a sample to be subjected to the deterioration promotion test is disposed in the container, and the gas supply means is controlled by the control means so that the partial pressure is 20% or more. A gas containing oxygen is supplied into the container. Further, the humidifying means is controlled by the control means, the humidity in the storage container is set to 70% RH or more, and the heating means is controlled by the control means, so that the temperature of the atmosphere in the storage container is set to a predetermined temperature. Warm up. Thereby, deterioration promotion processing can be performed under a certain condition.

  A seventh aspect of the present invention is the tire component member deterioration accelerating device according to the sixth aspect, wherein the gas supply means includes a high-pressure oxygen source and a high-pressure inert gas source, and oxygen and inert gas. Are mixed at a predetermined ratio determined in advance, and the pressure of the mixed gas composed of oxygen and inert gas is adjusted to a predetermined pressure and supplied into the storage container.

Next, the operation of the tire constituent member deterioration test apparatus according to claim 7 will be described.
In the deterioration test apparatus for tire constituent members according to claim 7, oxygen gas from a high-pressure oxygen source and inert gas from a high-pressure inert gas source can be mixed at a predetermined ratio, and oxygen and inert gas The pressure of the mixed gas composed of gas is adjusted to a predetermined pressure and supplied into the storage container.
The high pressure means a pressure higher than the atmospheric pressure.
As a specific example of the inert gas, for example, a gas such as nitrogen gas or argon gas can be used.

  As described above, according to the deterioration test method for a tire constituent member and the deterioration test apparatus for a tire constituent member of the present invention, it is possible to obtain data having good compatibility with deterioration characteristics due to actual use. It has the effect.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the deterioration promoting device 10 of this embodiment includes a storage pressure vessel 14 that stores a tire constituent member 12. The storage pressure vessel 14 includes an openable / closable lid (not shown) for allowing the tire constituent member 12 to enter and exit.

  An atmosphere heating heater 16 is provided on the outer surface of the storage pressure vessel 14. The atmosphere heating heater 16 is connected to a control device 18. When the atmosphere heating heater 16 is energized, the storage pressure vessel 14 is heated and the internal gas is heated.

The deterioration promoting device 10 is provided with a humidifying device 20 adjacent to the storage pressure vessel 14.
The humidifier 20 includes a water tank 22 that can store water 21 therein. A water vapor generating heater 24 is provided on the outer surface of the water tank 22. The water vapor generating heater 24 is connected to the control device 18. When the water vapor generating heater 24 is energized, the water tank 22 is heated and the internal water is heated to generate water vapor.

Adjacent to the humidifier 20 are an oxygen cylinder 26 filled with oxygen gas and an inert gas cylinder 28 filled with inert gas.
The oxygen cylinder 26 and the inert gas cylinder 28 are connected to a gas mixer 34 via pipes 30 and 32. The gas mixer 34 provides a mixed gas in which oxygen gas and inert gas are mixed in a predetermined ratio. The ratio of oxygen gas to inert gas is controlled by the control device 18.

The mixed gas from the gas mixer 34 is supplied into the water tank 22 via the pipe 36. A pressure regulating valve 38 controlled by the control device 18 and a mixed gas supply electromagnetic on-off valve 40 are provided in the middle of the pipe 36. The water tank 22 is provided with a pressure sensor 42, and the control device 18 can control the pressure adjustment valve 38 based on a pressure detection signal from the pressure sensor 42.
When the mixed gas is supplied to the water tank 22, the mixed gas is supplied to the storage pressure vessel 14 through the pipe 44 together with the water vapor generated in the tank.

The storage pressure vessel 14 is provided with a temperature sensor 46 and a humidity sensor 48. The temperature sensor 46 and the humidity sensor 48 are connected to the control device 18, and the control device 18 controls the atmosphere heating heater 16 based on the temperature detection signal from the temperature sensor 46 and from the humidity sensor 48. The water vapor generating heater 24 can be controlled based on the humidity detection signal.
Note that an exhaust pipe 50 is connected to the storage pressure vessel 14. An exhaust electromagnetic on-off valve 52 controlled by the control device 18 is provided in the middle of the pipe 50.

  The control device 18 automatically detects the gas mixer 34, the pressure adjustment valve 38, the mixed gas supply electromagnetic on-off valve 40, the exhaust gas based on detection signals (information) from the pressure sensor 42, the temperature sensor 46, and the humidity sensor 48. The electromagnetic solenoid valve 52 is controlled, and the oxygen partial pressure, temperature, and humidity inside the storage pressure vessel 14 are set to desired values. Of course, the operator inputs desired temperature, humidity, and pressure values in advance on the operation panel 54.

In the deterioration promoting apparatus 10 of the present embodiment, the pressure inside the storage pressure vessel 14 is in the range of 1.2 to 10 kg / cm ² , the oxygen partial pressure inside the storage pressure vessel 14 is at least 20% or more, and the storage pressure vessel The temperature of the atmosphere inside 14 can be set to 100 ° C., and the humidity of the atmosphere inside the storage pressure vessel 14 can be set within a range of 70% RH to 100% RH.

Next, the usage method of the deterioration promotion apparatus 10 of this embodiment is demonstrated.
In order to perform the deterioration promoting process of the tire component 12 using the deterioration accelerating device 10, first, the tire component 12 to be tested is placed inside the storage pressure vessel 14, and the lid (not shown) is closed. Seal.

  Here, the tire constituent member 12 includes, for example, the tire itself, a tire cut piece, a rubber cord composite (treat shape), a vulcanized rubber sheet piece, a steel cord piece embedded in rubber and vulcanized. Of course, other than these may be used. In addition to tire cut-out pieces cut out from actual tires, sample pieces manufactured by imitating tire cut-out pieces (ply pieces, vulcanized rubber sheet pieces, etc., which are vulcanized with a cord embedded in rubber) are also tires. It is synonymous with a structural member.

  When the operation panel 54 instructs the deterioration promotion process, the atmosphere heating heater 16 and the steam generating heater 24 are energized, the mixed gas supply electromagnetic on-off valve 40 and the exhaust electromagnetic on-off valve 52 are opened, and gas mixing is performed. The mixed gas from the vessel 34 is supplied into the water tank 22. Examples of the instruction content on the operation panel 54 include pressure, temperature, humidity, oxygen partial pressure, and deterioration processing time.

When a predetermined time has passed and the mixed gas containing water vapor is filled in the storage pressure vessel 14, the exhaust electromagnetic on-off valve 52 is closed, and the storage pressure vessel 14 is once sealed.
The control device 18 keeps the mixed gas supply electromagnetic on-off valve 40 and the exhaust electromagnetic on-off valve 52 at the set values while automatically repeating the opening and closing so that the conditions instructed by the operation panel 54 are satisfied. Control is performed and the environment in the storage pressure vessel 14 is kept constant for a predetermined time.
After a predetermined time (deterioration processing time) has elapsed, the tire constituent member 12 that has undergone the deterioration promotion process is taken out and subjected to various tests.

When evaluating the characteristics of the tire constituent member 12 after the deterioration treatment, for example, tire separation and adhesion evaluation for tires and tire cut pieces, rubber cord interface deterioration evaluation for rubber cord composite pieces, and rubber for vulcanized rubber sheet pieces Aging and curing evaluation, steel cord fatigue evaluation of steel cord pieces embedded in rubber and vulcanized. Of course, other tests may be used for the tire component 12.
Here, the adhesion evaluation test between the vulcanized rubber and the steel cord conforms to the JIS K6301 peeling test.
Moreover, the fatigue test of a steel cord is performed as follows, for example.
As shown in FIG. 2, the steel cord 56 with rubber taken out from the deteriorated tire or the tire cut piece is hung on three pulleys 58 having a diameter of 40 mm as shown in the figure, and the fixed pulley 62 is repeated left and right. The cord is subjected to repeated bending strain by moving 20 cm to cause fatigue fracture of the cord, and the number of iterations leading to cord fracture is evaluated. In FIG. 2, reference numeral 60 denotes a weight attached to the end of the steel cord 56.

In the deterioration test method for tire constituent members according to the present embodiment, the internal pressure of the storage pressure vessel 14 is within a range of 1.2 to 10 kg / cm ² , and the partial pressure of oxygen inside the storage pressure vessel 14 is at least 20% or more, Since the temperature of the atmosphere inside the storage pressure vessel 14 is set to 100 ° C. and the humidity of the atmosphere inside the storage pressure vessel 14 is set within the range of 70% RH to 100% RH, the deterioration promoting process is performed. Not only temperature and humidity, but also the deterioration promotion treatment is performed in an oxygen-enriched atmosphere, and the tire composition is in a deterioration environment that is close to that in actual use where the deterioration factors are combined and sufficiently accelerated. The deterioration of the member 12 can be promoted.

  In addition, because the use of accelerated deterioration by an oxygen-enriched atmosphere in the required high-humidity environment, the efficiency of the steel member and its peripheral members that are particularly susceptible to moisture is reproduced while reproducing the deterioration state in actual use. Degradation can be accelerated.

Next, the deterioration acceleration test of the tire constituent member of the present invention was compared with the conventional deterioration acceleration test.
Both the example, the conventional example 1 and the conventional example 2 were performed under the deterioration treatment conditions described in Table 1 below.
This deterioration promotion process assumes a case where a passenger car tire is used as a tire component and the vehicle travels in a humid area. The mixed gas used is a mixture of oxygen gas and nitrogen gas.
-Necessary degradation time index: The evaluation is an index display of the necessary degradation time until the cord surface of the cord / rubber interface is exposed and more than half of the cord surface is exposed.

試験の結果、比較例１では、劣化速度は速いものの、実際の劣化に対応していなかった。また、比較例２では、実際の劣化には近かったが、劣化速度が極めて遅かった。

As a result of the test, in Comparative Example 1, although the deterioration rate was fast, it did not correspond to the actual deterioration. In Comparative Example 2, the actual deterioration was close, but the deterioration rate was extremely slow.

  On the other hand, in the deterioration acceleration test of the present invention, it was found that the deterioration rate was fast, and the same result as that obtained when used in an actual humid area was obtained, and the reproducibility was excellent.

(A) is a whole block diagram of a deterioration promotion apparatus, (B) is a block diagram of a control system. It is a block diagram of the fatigue test apparatus of a cord.

Explanation of symbols

10 Deterioration Promoter 14 Storage Pressure Vessel (Container)
16 Atmosphere heating heater (heating means)
18 Control device (control means)
20 Humidifier (humidifier)
30 Piping (gas supply means)
32 Piping (gas supply means)
34 Gas mixer (gas supply means)

Claims (7)

A tire constituent member deterioration test method for evaluating characteristics of the tire constituent member after the tire constituent member is left for a predetermined time in an atmosphere set to a predetermined pressure, temperature, and humidity and subjected to deterioration promotion treatment. There,
A deterioration promoting test method for a tire constituent member, characterized in that the deterioration promoting treatment is performed in an atmosphere containing oxygen at a humidity of 70% RH or more and a partial pressure of 20% or more. The method for promoting the deterioration of a tire component according to claim 1, wherein the test is performed in an atmosphere containing 50% or more partial pressure of oxygen. 3. The deterioration promotion test for a tire component according to claim 1, wherein the deterioration promotion treatment is performed within a range of a pressure of 1.2 to 10 kg / cm ² and a temperature of 60 to 100 ° C. 3. Method. The tire component includes a vulcanized rubber and a steel cord vulcanized and bonded to the vulcanized rubber,
The tire structure member deterioration acceleration test according to any one of claims 1 to 3, wherein an adhesion evaluation test between the vulcanized rubber and the steel cord is performed after the deterioration acceleration treatment. Method. The tire structure member deterioration promotion test method according to any one of claims 1 to 4, wherein a fatigue test of the steel cord is performed after the deterioration promotion treatment. A storage container for storing a tire component; and
A gas supply means capable of supplying a gas containing 20% or more of oxygen by partial pressure in the container;
A humidifying means capable of setting the humidity in the container to 70% RH or higher;
Heating means capable of heating the atmosphere in the container;
Control means for controlling the gas supply means, the humidification means, and the heating means to control the temperature, humidity, and pressure in the container;
A deterioration accelerating device for a tire constituent member, comprising: The gas supply means has a high-pressure oxygen source and a high-pressure inert gas source. The gas supply means mixes oxygen and inert gas at a predetermined ratio, and sets the pressure of the mixed gas composed of oxygen and inert gas to a predetermined value. The tire structure member deterioration accelerating device according to claim 7, wherein the pressure is adjusted to a predetermined pressure and supplied into the housing container.

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