JP2008056055A - Color seal for tire and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color seal for a tire enabling improvement of a design value and visual recognition of a tire temperature state by changing the color due to ambient temperature and heat generation caused by traveling. <P>SOLUTION: The color seal for the tire comprises a display layer 2 of which color is reversibly changed due to temperature change to display information and an adhesive layer 3 for vulcanization and adhesion to the tire outer surface 6. The display layer 2 comprises a rubber composition which includes a rubber component, a non-carbon black-based filler, and temperature-sensitive color-changing microcapsules with, as encapsulated therein, a temperature-sensitive color-changing component of which color may reversibly change with temperature change and which is obtained by directly mixing and dispersing the microcapsules in the rubber component. The color seal is attached to the tire outer surface 6 and vulcanized and adhered to it to obtain the pneumatic tire. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire color seal that changes color due to a temperature change, and a pneumatic tire using the same.

  Conventionally, in pneumatic tires, various designs such as pictures, characters, symbols, photographs, and patterns are displayed on the outer surface of the tire as information that can be visually recognized, improving design value and recognizing and identifying tire information. To be done.

  When such information is displayed on a tire, it is generally performed to mark the tire. However, information stamped on the tire surface requires a mold with a pattern for each pattern, lacks versatility, can only be the same color as the tire surface, and the mold production cost is enormous, This contributes to an increase in manufacturing costs.

  Therefore, instead of the above-mentioned engraving, a tire color seal composed of a display layer in which various information is displayed in a color other than black, and an adhesive layer that laminates the display layer and vulcanizes and adheres to the outer surface of the tire. It has been proposed (see Patent Documents 1 and 2 below). According to such a color seal, versatility can be given to the mold at the time of vulcanization, and by being vulcanized and bonded to the outer surface of the tire, it does not cause peeling or dropping following the deformation of the tire. . However, since general pigments and dyes that do not change color are used for the display layer, the color seal has only one color and there is no color change, and the appeal to the user is low in terms of improving fashionability.

  In addition, a tire color seal having a display layer containing a phosphorescent phosphor has been proposed (see Patent Document 3 below), but in the case of a phosphorescent phosphor, visibility and design value are exhibited. Only at night.

Patent Document 4 listed below discloses a tire in which a temperature indicating means containing a temperature-sensitive color changing material is attached to a sidewall portion of the tire, and the temperature-sensitive color changing component is used as a microcapsule as the temperature-sensitive color changing material. It is also disclosed that a laminated body of a rubber layer and a base layer containing the temperature-sensitive color changing material is incorporated into a sidewall portion at the time of tire molding by using an encapsulated material. However, in patent document 4, what dispersed the said microcapsule in polyvinyl chloride (PVC) is used. For this reason, the dispersibility of the temperature-sensitive color changing material with respect to the rubber component is poor, and uniform color development as a rubber layer cannot be obtained. In addition, when a temperature-sensitive color changing material masterbatched with a resin such as PVC is used as described above, in order to uniformly disperse, it is necessary to mix and disperse at a temperature higher than the melting point of the resin. Breaking or thermal history can lead to microcapsule damage. Furthermore, in the case of such a resin master batch, compatibility with the rubber component becomes a problem, and it is necessary to select a rubber component that matches the resin.
Japanese Patent Laid-Open No. 10-2222069 JP 2005-178638 A JP 2003-118297 A US Patent Application Publication No. 2005/0139142

  The present invention has been made in view of the above points, and it is possible to improve the design value and to visually recognize the tire temperature state by changing the color due to the atmospheric temperature or the heat generated by the running, and to improve the workability and color development. An object is to provide an excellent tire color seal and a pneumatic tire using the same.

  The tire color seal according to the present invention includes a display layer that displays information by reversibly discoloring due to a temperature change, and an adhesive layer that is vulcanized and bonded to the outer surface of the tire, and the display layer includes a rubber component. And a thermosensitive color-changing microcapsule encapsulating a temperature-sensitive color-changing component that changes color reversibly with a temperature change, and a rubber composition obtained by directly mixing and dispersing the microcapsule in a rubber component It is characterized by this.

  Here, the temperature-sensitive color-changing component preferably includes an electron-donating color-forming organic compound, an electron-accepting compound, and a color-changing temperature adjusting agent. In this case, since the heat resistance is excellent, The discoloration effect can be maintained even after vulcanization molding.

  In addition, an ultraviolet prevention layer that suppresses ultraviolet rays incident on the display layer may be provided on the outer surface side of the display layer. In this case, the ultraviolet rays are blocked from entering the display layer, and discoloration of the display layer due to ultraviolet rays is suppressed. be able to.

  The pneumatic tire according to the present invention is such that the tire color seal is stuck to the outer surface of the tire and vulcanized.

  According to the present invention, the display layer containing the temperature-sensitive color-changing microcapsules changes color due to a temperature change such as the atmospheric temperature or internal heat generation during running. Therefore, compared with a color seal using conventional pigments, dyes, and phosphors, the design value is improved and the appeal to the user is high. Further, the tire temperature state can be visually confirmed, the safety of the tire is enhanced by visually recognizing the abnormal heat generation state, and the tire temperature can be used as a means for preventing tire damage due to impact during tire transportation by visually recognizing the low temperature embrittled state.

  In addition, since the above microcapsules are mixed and dispersed in the rubber component as they are without being dispersed in the resin, the microcapsules can be uniformly dispersed in the rubber matrix while suppressing the temperature rise as much as possible by the shearing force during rubber mixing. Excellent workability. Moreover, since it can disperse | distribute uniformly, the uniform coloring effect can be acquired as the whole display layer, the thermal history with respect to a microcapsule can be suppressed, the damage can be reduced, and the outstanding coloring property can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the tire color seal 1 according to the present embodiment displays on the tire surface information consisting of various patterns composed of at least one of patterns, characters, symbols, photographs, patterns, barcodes, and the like. Display layer 2 and an adhesive layer 3 that can be adhered to a tire on which the display layer 2 is disposed and laminated.

  As shown in FIG. 2, the display layer 2 comprises a temperature-sensitive color-changing rubber composition that changes color reversibly with changes in temperature. The temperature-color-changing rubber composition comprises a rubber component and a non-carbon. Contains a black filler and a temperature-sensitive color changing material. In the example of FIG. 2, (a) shows a state where information is displayed in red when the temperature is low, and (b) shows a state where information is displayed in white when the temperature is high.

  The rubber component is not particularly limited, and various rubber polymers can be used. For example, natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), ethylene propylene rubber (EPDM or EPM), butyl rubber (IIR), halogenated butyl rubber, chloroprene rubber (CR ), Acrylonitrile butadiene rubber (NBR) and the like, and these can be used alone or in combination of two or more. Preferably, halogenated butyl rubber having excellent weather resistance such as brominated butyl rubber (BR-IIR) and chlorinated butyl rubber (Cl-IIR) is used. More specifically, halogenated butyl rubber and natural rubber and / or poly It is preferable to use a blend rubber with isoprene rubber.

  Preferably, the rubber composition contains a non-carbon black filler as a filler and substantially does not contain carbon black. This is because when carbon black is blended, the coloring effect of the temperature-sensitive color changing material cannot be obtained. Examples of the non-carbon black filler include white fillers such as silica, clay, talc, alumina, calcium carbonate, magnesium carbonate, aluminum hydroxide, zinc oxide, magnesium oxide, and titanium oxide, It can be used alone or in combination of two or more. Although the compounding quantity of a non-carbon black type filler is not specifically limited, It is preferable that it is 40-120 weight part with respect to 100 weight part of rubber components.

  As the temperature-sensitive color-changing material, a temperature-sensitive color-changing microcapsule in which a temperature-sensitive color-changing component that reversibly changes color with temperature change is used is used. By microencapsulating, the composition of the temperature-sensitive color-changing component can be kept constant and a stable color-changing effect can be exhibited. As the temperature-sensitive color-changing component, those composed of an electron-donating color-forming organic compound, an electron-accepting compound, and a color-changing temperature adjusting agent are suitable for ensuring heat resistance against the rubber vulcanization temperature. is there.

  As such temperature-sensitive color-changing components, for example, those disclosed in JP-A Nos. 2003-31453 and 2005-220201 can be used.

  Specifically, the electron-donating color-forming organic compound is a component that develops a color reaction with an electron-accepting compound, and a leuco dye is usually used. As the leuco dye, known ones can be used, and examples thereof include triphenylmethane phthalide, fluoran, indolyl phthalide, leucooramine, and spiropyran. The color at the time of color development can be adjusted by using 2 or more types in combination.

  The electron-accepting compound is a color developer component that develops a color reaction with an electron-donating color-forming organic compound, such as phenols, bisphenols, triazoles, aromatic carboxylic acids, fatty acids. Group carboxylic acids, phosphoric acids, or esters thereof, ethers and metal salts.

  Further, the color change temperature adjusting agent is a desensitization that controls the color reaction temperature by inhibiting the transfer of electrons between the electron donating colorable organic compound and the electron accepting compound by melting or melting. For example, organic media such as alcohols, esters, ethers, and fatty acids can be used. The setting of the color change temperature by the color change temperature adjusting agent can be appropriately performed by changing the type and composition of the organic medium according to the purpose. For example, when the color is changed by normal running to improve fashionability In this case, the set temperature for discoloration may be set to 30 to 40 ° C. Further, in order to make it possible to visually recognize the abnormality of the sidewall portion during traveling at low internal pressure, the discoloration set temperature may be set to 45 to 60 ° C. Furthermore, in order to make the low temperature embrittlement state visible in the racing tire, the discoloration set temperature may be set to 0 to 10 ° C.

  In order to encapsulate such temperature-sensitive color-changing components, for example, a known microencapsulation method such as a coacervation method, an in situ polymerization method, or an interfacial polymerization method can be used. The average particle size of the microcapsules is not particularly limited, but is usually 0.5 to 100 μm, preferably 0.5 to 20 μm.

  Examples of such temperature-sensitive color-changing microcapsules include “Chromi Color” manufactured by Matsui Dye Chemical Co., Ltd. and “ETSD powder” manufactured by Nippon Capsule Products. However, as described later, since the microcapsules are directly mixed and dispersed in the rubber component, it is preferable to obtain and use a powdery material that is not masterbatched with a resin.

  The compounding amount of the thermochromic microcapsules is not particularly limited, but the rubber used for the display layer of the tire color seal is 1 to 20% by weight as a proportion of the whole rubber composition. Preferred as a composition.

  Since the rubber composition is vulcanized and molded together with the tire body, a vulcanizing agent is usually blended. As the vulcanizing agent, sulfur-based vulcanizing agents such as sulfur, thiuram polysulfide and morpholine derivatives are generally used, but non-sulfur-based crosslinking agents such as organic peroxides and metal peroxides are used. Also good. In addition, although the compounding quantity of a vulcanizing agent is not specifically limited, Usually, it is preferable that it is 0.1-10 weight part with respect to 100 weight part of rubber components.

  The rubber composition contains various additives such as stearic acid, zinc white, softener, coupling agent, plasticizer, and vulcanization accelerator that are commonly used in the rubber industry. can do. However, it is preferable that all of these additives are non-staining chemicals, that is, those which do not substantially color the base rubber component. Therefore, it is preferable that the temperature-sensitive color-changing rubber composition does not substantially contain a contaminating anti-aging agent.

  In preparing the rubber composition, the microcapsules are directly mixed and dispersed in a rubber component. That is, the microcapsules are stirred and mixed in the rubber component while being dispersed in a powder form without being dispersed in a resin such as PVC. The rubber polymer, which is a viscoelastic material, can uniformly disperse the powdery microcapsules in the matrix while suppressing the thermal history due to the shearing force during stirring and mixing.

  Specifically, for example, in the first step, the rubber component and the non-carbon black filler are added to the mixer and mixed, and the powdered microcapsules are added as they are, and mixed and stirred. In the step, a rubber composition is obtained by adding a vulcanizing agent thereto and mixing them. The mixer is not particularly limited as long as it can mix the rubber composition, and examples thereof include a Banbury mixer, a kneader, a roll mill, and a blender mixer.

  The display layer 2 is laminated and integrated on the surface of the adhesive layer 3 by sheeting the temperature-sensitive color-changing rubber composition. As shown in FIG. 1, the display layer 2 may be formed into a shape for displaying information by itself, or, although not shown, a cover that is formed in a simple sheet shape and forms a display shape on its surface. A rubber layer may be provided, and information may be displayed outside on the display layer that is not covered by the cover rubber layer.

  In addition, as the above information, various characters and designs such as tire manufacturer and shipping destination names and logos, tire rotation direction marks, tire product name characters, etc. are used. Are displayed in clear colors such as white, red, yellow, and blue. The thickness of the display layer 2 is not particularly limited, but is generally about 5 to 100 μm, preferably about 10 to 50 μm.

  The composition of the adhesive layer 3 is not particularly limited, but is preferably made of a rubber composition so as to be adhered to the outer surface of the tire and bonded by vulcanization. Further, the adhesive layer disclosed in JP-A-2005-178638 is disclosed. Is preferably applied. Specifically, a rubber composition in which 30 to 50 parts by weight of at least one of natural rubber and polyisoprene rubber and 50 to 70 parts by weight of halogenated butyl rubber are blended in 100 parts by weight of the rubber component is suitably used. In the rubber composition, the rubber component preferably occupies 70 vol% or more of the entire rubber composition. With such a rubber composition, due to the permeation-preventing performance of halogenated butyl rubber, the adhesive layer 3 provided between the tire and the display layer 2 blocks the transition of the anti-aging agent that bleeds from the tire to the display layer 2, Thereby, discoloration of the display layer 2 due to a contaminating compound such as an anti-aging agent can be prevented.

  The rubber composition constituting the adhesive layer 3 can be blended with various additives used in the normal rubber industry in addition to the rubber component. In particular, when the product body such as a tire is made of a black rubber composition, the adhesive layer 3 is assimilated with the tire body by blackening the adhesive layer 3 as a carbon black compound, and the color color of the display information is clearly highlighted. Can do. The thickness of the adhesive layer 3 is not particularly limited. For example, when the adhesive layer 3 is attached to the sidewall portion, it is preferably about 1/10 to 1/2 of the rubber thickness of the sidewall portion outside the carcass layer. .

  When the tire is molded, the color seal 1 is applied to an uncured tire body 4 at an arbitrary position on the outer surface 6 with the adhesive layer 3 facing the outer surface 6 side of the tire body 4 as shown in FIG. Then, by being vulcanized together with the tire body 4 in the vulcanization mold 5, the display layer 2 is vulcanized and bonded to the tire outer surface 6 with the display layer 2 exposed to the outside. Specifically, it is pressure-bonded to the inner surface of the mold 5 by vulcanization pressure, and as shown in FIG. 4, the color seal 1 is vulcanized and bonded in the rubber of the tire body 4 so that the tire surface 6 and the color seal 1 are bonded. A flattened pneumatic tire is obtained. Thus, since the color seal 1 is integrally vulcanized and bonded to the outer surface of the tire during vulcanization molding of the tire, it is excellent in workability compared to a case where it is separately attached to the tire after vulcanization, and the color seal tire Excellent followability to deformation, can prevent peeling and dropping, and can improve durability.

  The color seal 1 may be applied to the outer surface of the tire and then vulcanized into the mold 5; however, the color seal 1 may be placed at a predetermined position on the inner surface of the mold 5 and attached to the outer surface of the tire inside the mold 5 to be vulcanized and bonded. You can also

  The attaching position of the color seal 1 is not particularly limited, and examples thereof include a sidewall portion, a tread portion, and a bead portion. FIG. 5 shows a pneumatic tire in which a color seal 1 is affixed to the sidewall portion 7 of the tire. By adhering to the sidewall portion 7, a design decoration effect is achieved by the temperature-sensitive color-changing display layer 2. Can also be improved, and can also be used for visualizing the heat generation state of the tire.

  On the other hand, when affixed to the tread portion, it wears during traveling, but a low-temperature embrittled state before traveling can be visually confirmed. Especially for racing tires, because the tread rubber is composed of high Tg rubber, there is a concern that it may be damaged by impact during rim assembly or transportation. It can call attention and help prevent damage.

(Modification)
In the color seal of the present invention, in addition to the color seal 1 composed of the display layer 2 and the adhesive layer 3, an ultraviolet ray preventing layer 8 is provided on the outer surface side of the display layer 2 as shown in FIG. Also good. Accordingly, the display layer 2 is prevented from being discolored by blocking the incidence of the ultraviolet rays on the display layer 2, and if the anti-aging agent is transferred to the display layer 2, the reaction of both causes An increase in discoloration can be suppressed. In this case, the ultraviolet ray preventing layer 8 needs to be formed of a colorless and transparent layer for visually recognizing and recognizing the clear display content of the display layer 2.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Rubber composition for adhesive layer)
Table 1 below shows the composition of the rubber composition used for the adhesive layer.

(Rubber composition for display layer)
Using a Banbury mixer, rubber compositions of Examples 1 and 2 and Comparative Examples 1 to 3 were prepared according to the composition shown in Table 2 below. In the preparation, in the first step, the rubber component, clay, pigment (red MB, temperature-sensitive color changing materials A to C), stearic acid and zinc white are added and mixed, and then the second step. Then, a vulcanizing agent and a vulcanization accelerator were added and mixed to obtain a rubber composition.

  Here, “red MB” in Table 2 is a master batch in which a red pigment that does not change color due to a temperature change is blended with rubber.

  The “temperature-sensitive color-changing material A” and the “temperature-sensitive color-changing material B” are both encapsulated with a temperature-sensitive color-changing component containing an electron-donating color-forming organic compound, an electron-accepting compound, and a color-change temperature adjusting agent. It is a temperature-sensitive color-changing microcapsule, which is a powdery microcapsule itself that is not masterbatched with a resin. “Temperature-sensitive color change material A” has a set temperature of 30 ° C., a pigment that becomes red at a lower temperature and becomes colorless at a higher temperature. It becomes a colorless pigment.

  “Temperature-sensitive color change material C” is a dispersion of microcapsules similar to the temperature-sensitive color change material B in PVC (the pigment content is about 10% by weight).

(Creation of color seals and creation and evaluation of tires)
A color seal for evaluation of a two-layer structure in which a rubber composition for an adhesive layer is sheeted with a calendar to a thickness of 1 mm and a display layer having a thickness of 15 μm obtained by sheeting the rubber composition for a display layer on the obtained sheet surface is laminated ( 30 × 60 mm). The obtained color seal for evaluation was affixed to a predetermined position of the sidewall portion of the unvulcanized tire and vulcanized according to a conventional method to produce a pneumatic radial tire (tire size: 185 / 70R14). A discoloration test was performed on the obtained tire. In the discoloration test, each tire was allowed to stand at an ambient temperature of 20 ° C. and 40 ° C. for 1 hour or longer, and the color of the display layer of the color seal after the standing was visually confirmed.

As a result, as shown in Table 2, in Comparative Example 1 in which no pigment was blended or in Comparative Example 2 in which a simple red pigment was blended, no color change occurred due to a difference in temperature. In addition, in Comparative Example 3 in which the microcapsules mastered with PVC were added, the dispersibility with respect to the rubber component was poor and the microcapsules were dispersed non-uniformly, so that uniform color development as a whole display layer could not be obtained. It was. On the other hand, in each tire of Example 1 and Example 2, the display layer that was red when left at 20 ° C. was white when left at 40 ° C., and discoloration due to temperature change was confirmed. The color was uniform and looked good.

  The color seal for tires of the present invention can be used by sticking to the surface of various tires, and the display layer is discolored by the atmospheric temperature or heat generated by running, thereby improving the design decoration effect or in an abnormal heat generation state. The tire can be visually recognized to improve the safety of the tire, and the low temperature embrittled state can be visually recognized to prevent the tire from being damaged during transportation.

It is a perspective view of the color seal for tires concerning one embodiment of the present invention. It is a top view which shows the discoloration state of the same color sticker. It is the cross-sectional schematic diagram at the time of vulcanization | cure of the tire which stuck the same color seal. It is a principal part expanded sectional view of the vulcanized tire. It is a side view of a tire sidewall part. It is sectional drawing of the color seal | sticker of a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tire color seal, 2 ... Display layer, 3 ... Adhesive layer, 4 ... Tire main body, 5 ... Mold, 6 ... Tire outer surface, 7 ... Side wall part, 8 ... Ultraviolet prevention layer

Claims (4)

It comprises a display layer that displays information by reversibly discoloring due to temperature changes, and an adhesive layer that adheres to the outer surface of the tire.
The display layer includes a rubber component and a temperature-sensitive color-changing microcapsule encapsulating a temperature-sensitive color-changing component that changes color reversibly with a temperature change, and is obtained by directly mixing and dispersing the microcapsule in the rubber component. A tire color seal characterized by comprising the rubber composition described above.   The tire color seal according to claim 1, wherein the temperature-sensitive color-changing component comprises an electron-donating color-forming organic compound, an electron-accepting compound, and a color-changing temperature adjusting agent.   2. The tire color seal according to claim 1, wherein an ultraviolet preventing layer for suppressing ultraviolet rays incident on the display layer is provided on an outer surface side of the display layer. A pneumatic tire, wherein the tire color seal according to any one of claims 1 to 3 is affixed to a tire outer surface and vulcanized and bonded.

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