JP2006264562A - Color changing property inspection method of rubber product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color changing property inspection method of a rubber product capable of simply confirming color changing property due to migration of an age resister or wax or the like compounded in the rubber of a tire side part or the like. <P>SOLUTION: In the color changing property inspection method of the rubber product, a pressure element 2 is pressed on the surface of the rubber molding 1 to be inspected to apply contact pressure of 200 kPa or more, to inspect the presence or absence of color changing or degree of color changing on the surface of the rubber molding before and after applying the contact pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for inspecting discoloration of rubber products, and more specifically, discoloration inspection of rubber products that enables easy confirmation of discoloration due to migration of anti-aging agents and wax blended in rubber such as tire side portions. Regarding the method.

  When the pneumatic tire is mounted on a vehicle, the side portion thereof is most likely to receive sunlight. Therefore, an anti-aging agent and a wax are blended in the rubber constituting the side portion to prevent deterioration due to ultraviolet rays. However, these anti-aging agents and waxes have a phenomenon that they migrate to the tire surface over time and deposit in a film form. When the tire rim is assembled in such a state that the anti-aging agent and the wax are deposited in this manner, the film-like precipitate may be crystallized by an external stimulus, and the side surface may be changed to white.

  Since this whitening phenomenon does not affect the durability of the tire, there has been little concern in the past. However, as sales competition among car manufacturers intensifies in recent years, appearance deterioration in tires and premium tires to be mounted on new cars has been considered to be a factor in reducing merchandise.

Conventionally, as a measure to prevent the anti-aging agent and wax blended in the tire side part from migrating to the surface, the rubber layer of the side part is made into two layers, and the amount of anti-aging agent and wax blended in the inner layer side is the surface layer. There has been proposed a method of suppressing migration to the surface of the side part by increasing the blending amount on the side (Patent Documents 1, 2, etc.). However, there was no inspection method for easily confirming that whitening does not occur when the rim is assembled even if such a method is implemented. There was a trouble that I had to confirm.
JP 63-112636 A JP-A-4-108007

  The object of the present invention is to eliminate the above-mentioned conventional problems, and to make it possible to easily check the discoloration of rubber products by migrating anti-aging agents and waxes blended in rubber such as tire side portions. It is to provide a method.

  In the method for inspecting discoloration of a rubber product of the present invention that achieves the above object, a pressure is applied to the surface of a rubber molded body to be inspected to apply a surface pressure of 200 kPa or more, and rubber molding before and after the surface pressure is applied. It is characterized by inspecting the presence or absence of discoloration of the body surface or the degree of discoloration.

  According to the present invention, it is possible to confirm the presence or absence of discoloration or the degree of discoloration of the rubber molded body simply by applying a surface pressure of 200 kPa or more to the surface of the rubber molded body to be inspected by a pressurizer. It can be done easily and without any hassle.

  In the present invention, the rubber product is not particularly limited as long as it is a molded product made of a rubber composition. Preferably, the target is a pneumatic tire, a belt, a hose, and the like, and more preferably, the target is a pneumatic tire. In addition, since the object of the present invention is to examine the presence or absence or degree of discoloration of whitening, rubber products containing weathering agents such as anti-aging agents and waxes are directly targeted. Even rubber products that do not contain an agent can be confirmed to have no discoloration by using the discoloration inspection method of the present invention, so rubber products that do not contain anti-aging agents or weathering agents such as wax should also be inspected. Can do.

  As the rubber molded article for inspection used in the method for inspecting discoloration of the present invention, a rubber product may be used directly, or a sectioned sample molded from the same rubber composition as the rubber product may be used. Good.

  The inspection for discoloration is carried out by pressing a pressure element against the surface of the rubber molded body to be inspected and applying a surface pressure of 200 kPa or more.

  As the pressurizer, a plate, bar, or roller made of metal, resin, wood, or the like can be used. In the case of a plate-like or bar-like pressurizer, it is preferable to chamfer the edge of the surface portion that contacts the rubber molded body, and this chamfering can prevent damage to the rubber molded body. The chamfer is preferably a curved surface, and preferably has a curvature radius of 0.5 mm or more. Although an upper limit is not specifically limited, About 10 mm is good for a limit.

  The surface pressure applied by pressing the pressurizer must be 200 kPa or more. When the surface pressure is lower than 200 kPa, it is difficult to visually confirm even a rubber molded body having a color change property that turns white when the rim is assembled. Preferably, the surface pressure is 1 MPa or more, more preferably 5 MPa or more. The upper limit of the surface pressure is not particularly limited, but if the surface pressure is too large, the rubber molded body is damaged, so it is desirable to set the upper limit to about 50 MPa.

The contact area of the pressurizer when pressing the rubber molded body is preferably 1 cm ² or more. Moreover, it is preferable that the maximum contact length of the pressurizer at that time be 1 cm or more. If the contact area is smaller than 1 cm ² or the maximum contact length is shorter than 1 cm, it will be difficult to visually confirm the change in discoloration, even if it is a rubber molded product having discoloration. May be. The upper limit of the contact area and the maximum contact length is not particularly limited because it depends on the size of the rubber molded body. A larger value is preferable because it is easy to confirm discoloration, but from the viewpoint of operability, it is preferable to limit about 5 cm ² and 5 cm, respectively.

  Here, the maximum contact length of the pressurizer means the one corresponding to the diameter when a circumscribed circle is drawn in the contact shape formed by the pressurizer.

  In the present invention, when pressing the pressurizer to apply a surface pressure to the rubber molded body, it is possible to further improve the inspection accuracy for confirming discoloration by moving along the surface of the rubber molded body simultaneously with the pressing. it can. The moving distance is preferably at least 1 cm. The upper limit of the moving distance is not particularly limited and is preferably as large as possible. However, from the viewpoint of operability, the upper limit is preferably about 5 cm.

  In addition, the rubber molded body is held in a state where both end portions are gripped, and the center portion of the rubber molded body surface is displaced by pressing a pressurizer, and the rubber molded body surface is bent in a V shape with the pressurizer interposed therebetween. Even if it gives, improvement of the high inspection precision similar to the said movement operation can be aimed at. In this case, the distance L for displacing the central portion of the rubber molded body surface in the pressing direction is preferably at least 1 cm. Further, it is preferable that the angle θ sandwiched between the V-shaped V-shaped bent by this operation is in a range of 90 ° to 150 ° (see FIG. 2).

  The evaluation of the presence or absence of discoloration or the degree of discoloration of the rubber molded body may be performed visually, but preferably when the reflectance is measured using a reflectance measuring instrument and evaluated, particularly the degree of discoloration Can be converted into data, so that it is possible to perform a more accurate color change confirmation. In addition, automatic measurement can be made possible by using a reflectometer.

  FIG. 1 shows an example of a method for inspecting discoloration of a rubber product according to the present invention.

  Reference numeral 1 denotes a rubber molded body for inspection, which is composed of a rubber composition in which an antiaging agent and / or a weathering agent such as wax is blended. This rubber molded body 1 is placed on a support base 3 made of a rigid body, and a plate-like pressurizer 2 is pressed against the surface of the rubber molded body 1 to apply a load W corresponding to a surface pressure of 200 kPa or more. If necessary, the pressurizer 2 may be moved along the surface of the rubber molded body 1 in the direction of the arrow a. The moving distance is 1 cm or more.

  When the rubber molded body 1 has an anti-aging agent or wax migrated on its surface, the migrated precipitate crystallizes and turns white by an external stimulus given by the pressurizing operation of the pressurizer 2. Therefore, it can be confirmed that the antioxidant and the wax are deposited on the surface of the rubber molded body 1.

  FIG. 2 shows another example of the method for inspecting discoloration of a rubber product according to the present invention.

  In the embodiment shown in FIG. 2, both end portions 1e and 1e of the rubber molded body 1 to be inspected are held by gripping means (not shown). In this way, the pressurizer 2 is pressed against the center of the upper surface of the rubber molded body 1 holding the both ends 1e, 1e, a load W corresponding to a surface pressure of 200 kPa or more is applied, and a distance L of 1 cm or more is applied downward. The surface of the rubber molded body 1 is bent in a V shape with the pressurizer 2 interposed therebetween. Further, if necessary, the pressurizer 2 may be moved by 1 cm or more along the surface of the rubber molded body 1 in the direction of the arrow b.

  As in the inspection method of FIG. 1, when the anti-aging agent or wax is migrated on the surface of the rubber molded body 1 by this discoloration inspection, the precipitate on the surface crystallizes and whitens. It can be confirmed that an anti-aging agent, wax or the like is deposited on the surface of the rubber molded body 1.

  FIG. 3 shows still another example of the method for inspecting discoloration of a rubber product according to the present invention.

  In the embodiment of FIG. 3, a pneumatic tire 11 is directly used as a rubber molded body to be inspected, and a rubber composition containing an anti-aging agent and a weathering agent such as wax is used in the side portion. .

  In the discoloration inspection method, a rod-like pressurizer 12 is pressed against the side portion of the pneumatic tire 11 and a load W corresponding to a surface pressure of 200 kPa or more is applied. If necessary, the pressurizer 2 may be moved in the circumferential direction of the arrow c along the side surface of the pneumatic tire 11. The moving distance is 1 cm or more.

  By this discoloration test, when the anti-aging agent or wax is migrated on the surface of the side portion of the pneumatic tire 11, the precipitate on the surface crystallizes and whitens, so that the anti-aging agent or wax is on the surface. It can confirm that it has precipitated.

It is the schematic which shows an example of the discoloration property inspection method of the rubber product of this invention. It is the schematic which shows the other example of the discoloration test method of the rubber product of this invention. It is the schematic which shows the further another example of the discoloration property inspection method of the rubber product of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber molded object 2 Pressurizer 3 Support stand 11 Pneumatic tire 12 Pressurizer

Claims (8)

  Discoloration of a rubber product that presses against the surface of a rubber molded body to be inspected and applies a surface pressure of 200 kPa or more, and inspects the surface of the rubber molded body for the presence or absence of color change or the degree of color change before and after the surface pressure load Sex testing method.   The method for inspecting discoloration of a rubber product according to claim 1, wherein the pressurizing element is pressed against the surface of the rubber molded body and moved along the surface of the rubber molded body. The method for inspecting discoloration of a rubber product according to claim 1 or 2, wherein a contact area of the pressurizer with respect to the surface of the rubber molded body is 1 cm ² or more.   The method for inspecting discoloration of a rubber product according to any one of claims 1 to 3, wherein the maximum contact length of the pressurizer with respect to the surface of the rubber molded body is 1 cm or more.   The both ends of the rubber molded body are gripped, the central portion of the surface of the rubber molded body is displaced by at least 1 cm in the pressurizing direction by the pressurizer, and the surface of the rubber molded body is bent into a V shape. 4. The method for inspecting discoloration of a rubber product according to any one of 4 above.   The method for inspecting discoloration of a rubber product according to any one of claims 1 to 5, wherein the discoloration of the surface of the rubber molded body is evaluated by measuring reflectance.   The method for inspecting discoloration of a rubber product according to any one of claims 1 to 6, wherein the rubber molded body is a rubber composition containing an antioxidant and / or a wax. The method for inspecting discoloration of a rubber product according to any one of claims 1 to 7, wherein the rubber molded body is a pneumatic tire.

Images