JP2022029222A - Adhesive sealant material - Google Patents

Abstract

To provide an adhesive sealant material capable of exhibiting good sealability even under a low-temperature environment, suppressing flow during travel, securing sufficient adhesiveness to a tire, and satisfactorily maintaining these performances over a long period of time.SOLUTION: An adhesive sealant material constituting a sealant layer 10 arranged on an inner surface of a pneumatic tire is composed of a sealant material composition which contains 0.1-40 pts.mass of sulfur, more than 0 pt.mass and less than 1 pt.mass of a crosslinking aid, and 50 pts.mass or more of a plasticizer component based on 100 pts.mass of a rubber component. Viscosity V1 measured under a condition of -20°C immediately after vulcanization is set to 20 kPa s or less, and a viscosity difference ΔV between the viscosity V1 and viscosity V2 measured under a condition of -20°C after storage for two weeks in a 30°C environment from immediately after vulcanization is set to 5 kPa s or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive sealant material that constitutes a sealant layer of a self-sealing type pneumatic tire having a sealant layer on the inner surface of the tire.

In a pneumatic tire, it has been proposed to provide a sealant layer inside the inner liner layer in the tread portion in the tire radial direction (see, for example, Patent Document 1). In such a pneumatic tire (so-called self-sealing type pneumatic tire), when a foreign substance such as a nail pierces the tread portion, the sealant material constituting the sealant layer flows into the through hole, so that the air pressure is increased. It becomes possible to suppress the decrease in tires and maintain running.

In the above-mentioned self-sealing type pneumatic tire, if the viscosity of the sealant material is low, the sealant material can be expected to improve the sealing property in that it easily flows into the through hole. If the sealant material flows toward the tire center side due to the influence, and as a result, the through hole deviates from the tire center region, the sealant material may be insufficient and sufficient sealing property may not be obtained. On the other hand, if the viscosity of the sealant material is high, the flow of the sealant material can be prevented, but the sealant material is less likely to flow into the through hole, and the sealing property may be deteriorated. Therefore, the sealant material composition constituting the sealant material is required to balance the suppression of the flow of the sealant material with running and the assurance of good sealing property in a well-balanced manner.

In addition to this, the viscosity of the sealant generally has a temperature dependence, and the lower the temperature, the higher the viscosity tends to be. Therefore, in a low temperature environment such as when used in winter or in a cold region, the viscosity of the sealant material may increase and the sealing property may be impaired. Furthermore, depending on the temperature conditions, the sealant material solidifies, and when a foreign substance such as a nail pierces the tread, part of the sealant material around the through hole is lost due to the impact, and the through hole is properly filled. It may not be possible to seal. Therefore, the sealant material composition constituting the sealant material is required to exhibit good sealing properties even in a low temperature environment.

Further, since the sealant material functions only when a puncture occurs, it remains installed in the tire until the puncture occurs. Therefore, the component contained in the sealant material may be transferred to the rubber constituting the tire, the adhesiveness of the sealant material to the tire may be impaired, and the sealant material may be peeled off during running. Therefore, it is also required to maintain the performance as a sealant material for a long period of time, specifically, the adhesiveness to a tire in addition to the above-mentioned sealing property and fluidity.

Japanese Unexamined Patent Publication No. 2006-152110

An object of the present invention is to exhibit good sealing performance even in a low temperature environment, suppress flow during running, secure sufficient adhesiveness to a tire, and further improve these performances over a long period of time. The purpose is to provide an adhesive sealant material that can be maintained.

The adhesive sealant material of the present invention that achieves the above object is an adhesive sealant material constituting a sealant layer arranged on the inner surface of a pneumatic tire, and has 0.1 part of sulfur with respect to 100 parts by mass of the rubber component. It was composed of a sealant composition containing 40 parts by mass to 40 parts by mass, more than 0 parts by mass of a cross-linking aid and less than 1 part by mass, and 50 parts by mass or more of a plasticizer component, and was measured at -20 ° C immediately after vulcanization. The viscosity V1 is 20 kPa · s or less, and the viscosity difference ΔV between the viscosity V2 and the viscosity V1 measured under the condition of −20 ° C. after being stored in an environment of 30 ° C. for 2 weeks immediately after vulcanization is 5 kPa · s or less. It is characterized by that.

Since the adhesive sealant material of the present invention is composed of the sealant material composition having the above-mentioned composition and has the above-mentioned characteristics, it exhibits good sealing properties even in a low temperature environment and is a running sealant. It is possible to suppress the flow of the tire, secure sufficient adhesiveness to the tire, and further maintain good performance over a long period of time. In particular, since it contains sulfur (crosslinks are formed by sulfur), it is possible to enhance the adhesiveness to the inner surface of the tire, and the above-mentioned formulation ensures sufficient viscosity to obtain good sealing properties. It is advantageous to obtain an appropriate elasticity that does not flow during running or storage, and to achieve both of these performances in a well-balanced manner. Further, by using the above-mentioned composition, the temperature dependence of the physical properties of the adhesive sealant material can be reduced, which is advantageous for achieving both sealing properties and fluidity in a well-balanced manner in a low temperature environment. In addition to this, the sealing property in a low temperature environment can be ensured by setting the viscosity V1 in the above range, and further, by setting the viscosity difference ΔV as described above, the adhesive sealant material. It is possible to prevent the plasticizer component contained in the above from migrating to the rubber constituting the tire over time, and to maintain good performance of the adhesive sealant material for a long period of time. In the present invention, the "viscosity" is a value measured using a rotary viscometer under specified temperature conditions in accordance with JIS K6833-1: 2008. In particular, the viscosity V1 is a value measured by cooling the adhesive sealant immediately after vulcanization under the condition of −20 ° C. for 24 hours, and the viscosity V2 is a value measured immediately after vulcanization after being stored in an environment of 30 ° C. for 2 weeks. , The value measured by cooling the adhesive sealant material at −20 ° C. for 24 hours.

In the adhesive sealant material of the present invention, the viscosity difference ΔV between the viscosity V1 and the viscosity V2 is preferably 3 kPa · s or less. This is advantageous for ensuring sufficient sealing properties in a low temperature environment and maintaining good performance of the adhesive sealant material for a long period of time.

The adhesive sealant material of the present invention preferably contains 1 part by mass to 40 parts by mass of an organic peroxide with respect to 100 parts by mass of the rubber component. As described above, the organic peroxide is contained, and the cross-linking is performed by the combined use of the above-mentioned sulfur and the organic peroxide, so that the viscosity is sufficient to obtain good sealing property, and the viscosity is secured during running or storage. It is advantageous to obtain an appropriate elasticity that does not flow and to achieve both of these performances in a well-balanced manner. In addition, such a formulation can reduce the temperature dependence of the physical properties of the adhesive sealant material, which is advantageous for achieving a good balance of sealing property, storability, and fluidity in a low temperature environment. ..

The adhesive sealant material of the present invention preferably contains 10% by mass or more of butyl rubber with respect to 100% by mass of the rubber component. Further, it is preferable that the butyl rubber contains chlorinated butyl rubber and the content of the chlorinated butyl rubber is 5% by mass or more with respect to 100% by mass of the rubber component. With such a composition, the adhesiveness to the inner surface of the tire can be improved.

In the adhesive sealant material of the present invention, the plasticizer component is preferably a liquid polymer. In particular, it is preferable that this liquid polymer is paraffin oil. Further, the molecular weight of paraffin oil is preferably 800 or more. This makes it possible to reduce the temperature dependence of the physical properties of the adhesive sealant material, which is advantageous for ensuring good sealing properties in a low temperature environment.

The adhesive sealant material of the present invention is preferably vulcanized under the conditions of a vulcanization temperature of 150 ° C. or higher and a vulcanization time of 5 to 60 minutes. By vulcanizing under these conditions, it is possible to prevent unreacted sulfur from remaining in the adhesive sealant material, which is advantageous for maintaining good performance of the adhesive sealant material over a long period of time. Become.

In the pneumatic tire provided with the sealant layer made of the above-mentioned adhesive sealant material of the present invention, the excellent physical properties of the above-mentioned adhesive sealant material are good while suppressing the flow of the adhesive sealant material due to running. The sealing property can be exhibited, and in particular, good sealing property can be ensured even in a low temperature environment. In addition, the above-mentioned formulation and physical properties prevent the plasticizer component contained in the adhesive sealant material from migrating to the rubber constituting the tire over time, so that the performance of the adhesive sealant material is good for a long period of time. Can be maintained at.

It is a cross-sectional view of the meridian which shows an example of the pneumatic tire of this invention.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, for example, the pneumatic tire of the present invention (self-sealing type pneumatic tire) is arranged on a tread portion 1 extending in the tire circumferential direction to form an annular shape and on both sides of the tread portion 1. It includes a pair of sidewall portions 2 and a pair of bead portions 3 arranged inside the sidewall portion 2 in the tire radial direction. In FIG. 1, the reference numeral CL indicates the tire equator. Although FIG. 1 is a cross-sectional view of the meridian, the tread portion 1, the sidewall portion 2, and the bead portion 3 each extend in the tire circumferential direction to form an annular shape, whereby the pneumatic tire is formed. The toroidal basic structure of is constructed. Further, the other tire components in the meridian cross-sectional view also extend in the tire circumferential direction to form an annular shape unless otherwise specified.

In the example of FIG. 1, a carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the vehicle around the bead core 5 and the bead filler 6 arranged in each bead portion 3. The bead filler 6 is arranged on the outer peripheral side of the bead core 5, and is wrapped by a main body portion and a folded portion of the carcass layer.

A plurality of layers (two layers in FIG. 1) of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Among these plurality of belt layers 7, the layer having the smallest belt width is referred to as the minimum belt layer 7a, and the layer having the largest belt width is referred to as the maximum belt layer 7b. Each belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set to, for example, in the range of 10 ° to 40 °. A belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7 in the tread portion 1. In the illustrated example, two belt reinforcing layers 8 are provided, one is a full cover layer covering the entire width of the belt layer 7, and the other is an edge cover layer arranged on the outer peripheral side of the full cover layer and covering only the end portion of the belt layer 7. ing. The belt reinforcing layer 8 includes an organic fiber cord oriented in the tire circumferential direction, and the angle of the organic fiber cord with respect to the tire circumferential direction is set to, for example, 0 ° to 5 °.

An inner liner layer 9 is provided on the inner surface of the tire along the carcass layer 4. The inner liner layer 9 is a layer for preventing the air filled in the tire from permeating to the outside of the tire. The inner liner layer 9 is composed of, for example, a rubber composition mainly composed of butyl rubber having an air permeation prevention property. Alternatively, it may be composed of a resin layer having a thermoplastic resin as a matrix. In the case of the resin layer, the elastomer component may be dispersed in the matrix of the thermoplastic resin.

As shown in FIG. 1, a sealant layer 10 is provided inside the inner liner layer 9 in the tread portion 1 in the tire radial direction. In particular, the sealant layer 10 is provided on the inner surface of the tire corresponding to the region where foreign matter such as a nail may pierce during traveling, that is, the ground contact region of the tread portion 1. In particular, it is preferable to provide the sealant layer 10 in a range wider than the width of the minimum belt layer 7a. The sealant material composition of the present invention is used for the sealant layer 10. The sealant layer 10 is attached to the inner surface of a pneumatic tire having the above-mentioned basic structure, and when a foreign substance such as a nail pierces the tread portion 1, the sealant layer 10 is formed in the through hole thereof. The adhesive sealant material flows in and seals the through holes, thereby suppressing a decrease in air pressure and making it possible to maintain running.

The sealant layer 10 has a thickness of, for example, 0.5 mm to 5.0 mm. By having such a thickness, it is possible to suppress the flow of the sealant during traveling while ensuring good sealing performance. Further, the workability when the sealant layer 10 is attached to the inner surface of the tire is also improved. If the thickness of the sealant layer 10 is less than 0.5 mm, it becomes difficult to secure sufficient sealing properties. If the thickness of the sealant layer 10 exceeds 5.0 mm, the weight of the tire increases and the rolling resistance deteriorates. The thickness of the sealant layer 10 is an average thickness.

The sealant layer 10 can be formed by later attaching it to the inner surface of the vulcanized pneumatic tire. For example, it is preferable to attach the adhesive sealant material obtained by vulcanizing the sealant material composition described later to the inner surface of the tire to form the sealant layer 10. When attaching the adhesive sealant material, the adhesive sealant material molded into a sheet shape is attached over the entire circumference of the inner surface of the tire, or the adhesive sealant material molded into a string shape or a band shape is applied inside the tire. It can be attached to the surface in a spiral shape.

The vulcanization conditions for vulcanizing the sealant material composition described later in order to obtain the above-mentioned adhesive sealant material are not particularly limited, but are required for the composition of the sealant material composition described later and the adhesive sealant material. Considering the physical properties, the vulcanization temperature is preferably 150 ° C. or higher, more preferably 160 ° C. to 200 ° C., and the vulcanization time is preferably 5 minutes to 60 minutes, more preferably 10 minutes to 30 minutes. It is good. By vulcanizing under these conditions, it is possible to prevent unreacted sulfur from remaining in the adhesive sealant material, which is advantageous for maintaining good performance of the adhesive sealant material over a long period of time. Become.

Since the present invention mainly relates to an adhesive sealant material (sealant material composition) used for the sealant layer 10 of the above-mentioned self-sealing type pneumatic tire, the basic structure of the pneumatic tire and the sealant layer 10 The structure of is not limited to the above example.

For the adhesive sealant material of the present invention, the viscosity measured under the condition of -20 ° C immediately after vulcanization is V1, and the viscosity measured immediately after vulcanization under the condition of -20 ° C after storing in the environment of 30 ° C for 2 weeks is V2. Then, the viscosity V1 is 20 kPa · s or less, preferably 5 kPa · s to 15 kPa · s, and the viscosity difference ΔV between the viscosity V1 and the viscosity V2 is 5 kPa · s or less, preferably 3 kPa · s or less. When the adhesive sealant material having such characteristics is used for the sealant layer 10 of a pneumatic tire, the viscosity V1 is sufficiently low to exhibit good sealing performance even in a low temperature environment, and further, the viscosity difference. Since ΔV is small, the performance of the adhesive sealant material can be well maintained for a long period of time. At this time, if the viscosity V1 exceeds 20 kPa · s, the sealing property in a low temperature environment deteriorates. If the viscosity difference ΔV exceeds 5 kPa · s, it becomes difficult to maintain the performance of the adhesive sealant material for a long period of time.

The viscosity V2 is not particularly limited as long as it is calculated from the range of the viscosity V1 and the above-mentioned range of the viscosity difference ΔV, but is preferably 5 kPa · s to 20 kPa · s, more preferably 7 kPa · s to 15 kPa ·. It should be s.

In addition to having the above-mentioned physical properties, the adhesive sealant material of the present invention is composed of a sealant material composition having the following composition (hereinafter referred to as the sealant material composition of the present invention).

In the sealant material composition of the present invention, the rubber component may contain a butyl rubber. The ratio of the butyl rubber to the rubber component is preferably 10% by mass or more, more preferably 20% by mass to 90% by mass. By including the butyl rubber in this way, good adhesion to the inner surface of the tire can be ensured. If the proportion of the butyl rubber is less than 10% by mass, the adhesiveness to the inner surface of the tire cannot be sufficiently ensured.

In the sealant material composition of the present invention, it is preferable to contain halogenated butyl rubber as the butyl rubber. Examples of the halogenated butyl rubber include chlorinated butyl rubber and brominated butyl rubber, and chlorinated butyl rubber can be particularly preferably used. When chlorinated butyl rubber is used, the ratio of chlorinated butyl rubber to 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass to 85% by mass. By containing halogenated butyl rubber (chlorinated butyl rubber), the reactivity between the rubber component and the cross-linking agent and organic peroxide described later is enhanced, which is advantageous for ensuring the sealing property and suppressing the flow of the sealant at the same time. Become. In addition, the processability of the sealant material composition can be improved. When the proportion of chlorinated butyl rubber is less than 5% by mass, the reactivity between the rubber component and the cross-linking agent or organic peroxide described later is not sufficiently improved, and the desired effect cannot be sufficiently obtained.

In the sealant material composition of the present invention, the total amount of butyl rubber does not have to be halogenated butyl rubber (chlorinated butyl rubber), and non-halogenated butyl rubber can also be used in combination. Examples of the non-halogenated butyl rubber include unmodified butyl rubber usually used in a sealant material composition, for example, BUTYL-065 manufactured by JSR Corporation, BUTYL-301 manufactured by LANXESS Corporation, and the like. When the halogenated butyl rubber and the non-halogenated butyl rubber are used in combination, the blending amount of the non-halogenated butyl rubber is preferably less than 20% by mass, more preferably less than 10% by mass in 100% by mass of the rubber component.

In the sealant material composition of the present invention, it is preferable to use two or more kinds of rubber together as the butyl rubber. That is, it is preferable to use another halogenated butyl rubber (for example, brominated butyl rubber) or a non-halogenated butyl rubber in combination with the chlorinated butyl rubber. Since chlorinated butyl rubber, other halogenated butyl rubber (brominated butyl rubber), and non-halogenated butyl rubber have different vulcanization rates, if at least two types are used in combination, the difference in vulcanization rate is caused. , The physical properties (viscosity, elasticity, etc.) of the sealant material composition after vulcanization do not become uniform. That is, due to the distribution (variation in concentration) of rubbers having different vulcanization rates in the sealant material composition, a relatively hard portion and a relatively soft portion are mixed in the sealant layer after vulcanization. As a result, the fluidity is suppressed in the relatively hard portion, and the sealing property is exhibited in the relatively soft portion, which is advantageous for achieving both of these performances in a well-balanced manner.

In the sealant material composition of the present invention, a diene-based rubber other than the butyl-based rubber can be blended as the rubber component. Other diene-based rubbers include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), and chloroprene. Rubber generally used for sealant material compositions such as rubber (CR) and acrylonitrile butadiene rubber (NBR) can be used. These other diene rubbers can be used alone or as any blend.

In the sealant material composition of the present invention, sulfur is always blended as a cross-linking agent. The blending amount of sulfur is 0.1 part by mass to 40 parts by mass, preferably 0.5 part by mass to 20 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component. As a result, the adhesive sealant material is crosslinked by sulfur, so that the adhesiveness to the tire can be improved. If the amount of sulfur blended is less than 0.1 parts by mass, it is substantially equivalent to containing no cross-linking agent, and appropriate cross-linking cannot be performed. If the amount of sulfur blended exceeds 40 parts by mass, the sealant composition is crosslinked too much and the sealing property is deteriorated. Even if a cross-linking agent other than sulfur (for example, quinonedioxime, zinc oxide, etc.) is used, sufficient adhesiveness to the tire cannot be ensured.

In the sealant material composition of the present invention, it is preferable to add an organic peroxide together with the above-mentioned cross-linking agent (sulfur). By blending sulfur and an organic peroxide in combination in this way, it is possible to realize suitable cross-linking in order to ensure both sealing properties and prevent the flow of the sealant. The blending amount of the organic peroxide is preferably 1 part by mass to 40 parts by mass, and more preferably 1.0 part by mass to 20 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component. If the blending amount of the organic peroxide is less than 1 part by mass, the amount of the organic peroxide is too small to sufficiently carry out cross-linking, and the desired physical properties cannot be obtained. If the blending amount of the organic peroxide exceeds 40 parts by mass, the sealing property of the sealant material composition is excessively crosslinked and the sealing property is deteriorated.

When the sulfur and the organic peroxide are used in combination in this way, the mass ratio A / B of the sulfur compounding amount A and the organic peroxide compounding amount B is preferably 5/1 to 1/200, more preferably. Should be 1/10 to 1/20. By setting such a blending ratio, it becomes possible to achieve both ensuring the sealing property and preventing the flow of the sealant in a more balanced manner.

Examples of the organic peroxide include dicumyl peroxide, t-butyl cumyl peroxide, benzoyl peroxide, dibenzoyl peroxide, butyl hydroperoxide, p-chlorobenzoyl peroxide, 1,1,3,3-. Examples thereof include tetramethylbutyl hydroperoxide. In particular, an organic peroxide having a 1-minute half-life temperature of 100 ° C. to 200 ° C. is preferable, and among the above-mentioned specific examples, dicumyl peroxide and t-butyl cumyl peroxide are particularly preferable. In the present invention, the "1 minute half-life temperature" generally adopts the value described in "Organic Peroxide Catalog 10th Edition" of NOF CORPORATION, and if not described, it is described in the catalog. The value obtained from the thermal decomposition in the organic solvent is adopted in the same manner as the above method.

A cross-linking aid is always blended with the above-mentioned cross-linking agent (sulfur) in the sealant material composition of the present invention. The cross-linking aid is a compound that acts as a cross-linking reaction catalyst when blended with a cross-linking agent containing a sulfur component. By blending a cross-linking agent (sulfur) and a cross-linking aid, the vulcanization rate can be increased and the productivity of the sealant material composition can be increased. The blending amount of the cross-linking aid is preferably more than 0 parts by mass and less than 1 part by mass, and more preferably 0.1 parts by mass to 0.9 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component. By suppressing the blending amount of the cross-linking aid in this way, it is possible to suppress the deterioration (heat deterioration) of the sealant material composition while promoting the cross-linking reaction as a catalyst. If the blending amount of the cross-linking aid is 1 part by mass or more, the effect of suppressing thermal deterioration cannot be sufficiently obtained. Since the cross-linking aid acts as a cross-linking reaction catalyst by blending with the cross-linking agent containing a sulfur component as described above, the cross-linking reaction catalyst can be coexisted with an organic peroxide instead of the sulfur component. However, a large amount of cross-linking aid must be used, which accelerates thermal deterioration.

When the cross-linking agent (sulfur) and the cross-linking aid are used in combination, the blending amount of the cross-linking agent (sulfur) is preferably 50% by mass to 400% by mass, more preferably 100% by mass to 200% by mass, based on the blending amount of the cross-linking aid. It should be. By blending the cross-linking agent (sulfur) and the cross-linking aid in a well-balanced manner in this way, the function of the cross-linking aid as a catalyst can be satisfactorily exhibited, and both ensuring the sealing property and preventing the flow of the sealant are achieved. Will be advantageous. If the blending amount of the cross-linking agent (sulfur) is less than 50% by mass of the blending amount of the cross-linking aid, the fluidity is lowered. When the blending amount of the cross-linking agent (sulfur) exceeds 400% by mass of the blending amount of the cross-linking aid, the deterioration resistance is lowered.

Examples of the cross-linking aid include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamate-based, aldehyde-amine-based, aldehyde-ammonia-based, imidazoline-based, and xanthate acid-based compounds ( A vulcanization accelerator) can be exemplified. Among these, thiazole-based, thiuram-based, guanidine-based, and dithiocarbamate-based vulcanization accelerators can be preferably used. Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole and dibenzothiazyl disulfide. Examples of the thiuram-based vulcanization accelerator include tetramethylthium monosulfide and tetramethylthium disulfide. Examples of the guanidine-based vulcanization accelerator include diphenylguanidine and dioltotrilguanidine. Examples of the dithiocarbamate-based vulcanization accelerator include sodium dimethyldithiocarbamate and sodium diethyldithiocarbamate. In particular, in the present invention, it is preferable to use a thiazole-based or thiuram-based vulcanization accelerator, and it is possible to suppress variations in the performance of the obtained sealant material composition.

A compound that actually functions as a cross-linking agent, such as quinonedioxime, may be referred to as a cross-linking aid for convenience, but the cross-linking aid in the present invention is cross-linked by a cross-linking agent (sulfur) as described above. Since it is a compound that functions as a reaction catalyst, quinonedioxime does not fall under the cross-linking aid in the present invention.

A plasticizer component (for example, a liquid polymer) is always blended in the sealant material composition of the present invention. By blending the plasticizer component in this way, the viscosity of the adhesive sealant material can be increased and the sealing property can be improved. The blending amount of the plasticizer component is 50 parts by mass or more, preferably 50 parts by mass to 400 parts by mass, and more preferably 70 parts by mass to 200 parts by mass with respect to 100 parts by mass of the above-mentioned rubber component. If the blending amount of the plasticizer component is less than 50 parts by mass, the effect of increasing the viscosity of the adhesive sealant material may not be sufficiently obtained. If the blending amount of the plasticizer component exceeds 400 parts by mass, the flow of the sealant cannot be sufficiently prevented.

As the plasticizer component, a liquid polymer can be exemplified as described above, but a liquid polymer that can be co-crosslinked with the rubber component (butyl rubber) in the sealant material composition is particularly preferable. Examples of such liquid polymers include paraffin oil, polybutene oil, polyisoprene oil, polybutadiene oil, polyisobutene oil, aroma oil, polypropylene glycol and the like. Paraffin oil, polybutene oil, polyisoprene oil, polybutadiene oil, aroma oil, polypropylene from the viewpoint of keeping the temperature dependence of the physical properties of the sealant composition low and ensuring good sealing properties in a low temperature environment. Glycol is preferable, and paraffin oil is particularly preferable. The use of paraffin oil is advantageous for setting the viscosity in a low temperature environment to an appropriate range. The molecular weight of the liquid polymer is preferably 800 or more, more preferably 1000 or more, and further preferably 1200 or more and 3000 or less. By using a tire having a large molecular weight in this way, it is possible to prevent the plasticizer component (oil component) from migrating from the sealant layer provided on the inner surface of the tire to the tire body and affecting the tire.

The adhesive sealant material of the present invention exhibits good sealing properties even in a low temperature environment by combining the above-mentioned physical properties (viscosity) and composition, suppresses the flow of the sealant during running, and further, for a long period of time. These performances can be maintained satisfactorily over the years. In particular, the inclusion of sulfur (crosslinking with sulfur) can enhance the adhesiveness to the inner surface of the tire, and the above-mentioned formulation ensures sufficient viscosity to obtain good sealing properties. It is possible to obtain an appropriate elasticity that does not flow during running or storage, and to achieve both of these performances in a well-balanced manner. Further, by adopting the above-mentioned composition, the temperature dependence of the physical properties of the sealant material composition can be lowered, and the sealing property and the fluidity in a low temperature environment can be compatible in a well-balanced manner. In addition to this, by setting the viscosity V1 in the above range, the sealing property in a low temperature environment can be ensured, and further, by setting the viscosity difference ΔV as described above, the adhesive sealant material. It is possible to prevent the plasticizer component contained in the above from migrating to the rubber constituting the tire over time, and to maintain good performance of the adhesive sealant material for a long period of time. Therefore, the adhesive sealant material of the present invention can be suitably used for the sealant layer 10 of a self-sealing type pneumatic tire. The tire provided with the sealant layer 10 made of the adhesive sealant material of the present invention has the excellent performance of the adhesive sealant material based on the above-mentioned physical properties and the combination of the above-mentioned physical properties, so that the through holes created by the puncture can be formed in a low temperature environment. However, it can be reliably closed and its performance can be maintained for a long period of time.

Hereinafter, the present invention will be further described with reference to Examples, but the scope of the present invention is not limited to these Examples.

A sealant material composition having the compositions shown in Tables 1 and 2 was prepared. Specifically, the rubber component and carbon black are kneaded with a 1.7 L Banbury mixer for 10 minutes, then the plasticizer component (liquid polymer) is added, and finally the cross-linking agent (sulfur) and the organic peroxide are added. Then, each sealant material composition was prepared by kneading for another 10 minutes. This sealant material composition was vulcanized under the conditions shown in Tables 1 and 2 to obtain an adhesive sealant material (Comparative Examples 1 to 10 and Examples 1 to 5).

Tables 1 and 2 also show the viscosities of the adhesive sealant material. Viscosity V1 is the viscosity of the adhesive sealant material immediately after vulcanization, and immediately after vulcanization under the conditions of each example shown in Tables 1 and 2, the adhesive sealant material of each example is subjected to the condition of −20 ° C. It is a value measured after cooling for 24 hours. Viscosity V2 is the viscosity of the adhesive sealant material after being stored in an environment of 30 ° C. for 2 weeks immediately after vulcanization, and is a value measured by cooling the adhesive sealant material after storage for 24 hours under the condition of −20 ° C. Is. Viscosity V3 is the viscosity of the adhesive sealant material after being stored in an environment of 25 ° C. for 10 days immediately after vulcanization, and is a value measured by cooling the adhesive sealant material after storage for 24 hours under the condition of −20 ° C. Is. Each viscosity was measured using a rotary viscometer in accordance with JIS K6833-1: 2008.

For these adhesive sealant materials, the sealing property, the adhesiveness, and the fluidity during running were evaluated by the following test methods, and the results are also shown in Tables 1 and 2.

Sealability (Condition 1)
A test tire is manufactured by pasting each adhesive sealant immediately after vulcanization on the inner side of the inner liner layer in the tread portion of a pneumatic tire (tire size: 255 / 40R20) having the basic structure shown in FIG. did. Then, after cooling each test tire under the condition of temperature -20 ° C for 24 hours, it is attached to the wheel of rim size 20 × 9J and mounted on the test vehicle, and the initial air pressure is 250 kPa, the load is 8.5 kN, and the temperature is -20 ° C. A nail having a diameter of 4.0 mm was driven into the tread portion, and the air pressure was measured after the tire was allowed to stand in a −20 ° C. environment for 1 hour with the nail removed. The evaluation results are shown in the following five stages. It should be noted that if the score of the evaluation result is "3" or more, sufficient sealing property is exhibited, and the larger the score, the better the sealing property is exhibited.
5: Air pressure after standing still is 240 kPa or more and 250 kPa or less 4: Air pressure after standing is 230 kPa or more and less than 240 kPa 3: Air pressure after standing is 215 kPa or more and less than 230 kPa 2: Air pressure after standing is 200 kPa or more and less than 240 kPa Less than 215 kPa 1: Pneumatic pressure after standing is less than 200 kPa

Sealability (Condition 2)
A test tire is manufactured by pasting each adhesive sealant material inside the inner liner layer in the tread portion of a pneumatic tire (tire size: 255 / 40R20) having the basic structure shown in FIG. 1 in the tire radial direction. Was stored in a 30 ° C. environment for 2 weeks. Then, after cooling each test tire under the condition of temperature -20 ° C for 24 hours, it is attached to the wheel of rim size 20 × 9J and mounted on the test vehicle, and the initial air pressure is 250 kPa, the load is 8.5 kN, and the temperature is -20 ° C. A nail having a diameter of 4.0 mm was driven into the tread portion, and the air pressure was measured after the tire was allowed to stand in a −20 ° C. environment for 1 hour with the nail removed. The evaluation results are shown in the following five stages. It should be noted that if the score of the evaluation result is "3" or more, sufficient sealing property is exhibited, and the larger the score, the better the sealing property is exhibited.
5: Air pressure after standing still is 240 kPa or more and 250 kPa or less 4: Air pressure after standing is 230 kPa or more and less than 240 kPa 3: Air pressure after standing is 215 kPa or more and less than 230 kPa 2: Air pressure after standing is 200 kPa or more and less than 240 kPa Less than 215 kPa 1: Pneumatic pressure after standing is less than 200 kPa

Adhesiveness (Condition 1)
A test tire is manufactured by pasting each adhesive sealant immediately after vulcanization on the inner side of the inner liner layer in the tread portion of a pneumatic tire (tire size: 255 / 40R20) having the basic structure shown in FIG. did. Then, each test tire is attached to a wheel having a rim size of 20 × 9J, mounted on the test vehicle, and after traveling 100,000 km under the conditions of an air pressure of 250 kPa, a load of 5.0 kN, and a speed of 80 km / h, the splice portion of the adhesive sealant material is used. The peeling condition of the adhesive sealant material was visually confirmed. The evaluation result is "good" when peeling does not occur, "possible" when the area where peeling occurs is less than 1/3 of the width of the sealant layer from the end of the splice portion in the tire width direction, and peeling occurs. The case where the generated region is 1/3 or more of the width of the sealant layer from the end portion in the tire width direction of the splice portion is shown as "impossible".

Adhesiveness (Condition 2)
A test tire is manufactured by pasting each adhesive sealant material inside the inner liner layer in the tread portion of a pneumatic tire (tire size: 255 / 40R20) having the basic structure shown in FIG. 1 in the tire radial direction. Was stored in a 30 ° C. environment for 2 weeks. Then, each test tire is attached to a wheel having a rim size of 20 × 9J, mounted on the test vehicle, and after traveling 100,000 km under the conditions of an air pressure of 250 kPa, a load of 5.0 kN, and a speed of 80 km / h, the splice portion of the adhesive sealant material is used. The peeling condition of the adhesive sealant material was visually confirmed. The evaluation result is "good" when peeling does not occur, "possible" when the area where peeling occurs is less than 1/3 of the width of the sealant layer from the end of the splice portion in the tire width direction, and peeling occurs. The case where the generated region is 1/3 or more of the width of the sealant layer from the end portion in the tire width direction of the splice portion is shown as "impossible".

Fluidity during running Each adhesive sealant immediately after vulcanization is attached to the inside of the inner liner layer in the tire radial direction in the tread portion of a pneumatic tire (tire size: 255 / 40R20) having the basic structure shown in FIG. I made a test tire. Then, the test tire was attached to a wheel having a rim size of 20 × 9J, mounted on a drum tester, and traveled for 1 hour under the conditions of an air pressure of 220 kPa, a load of 8.5 kN, and a traveling speed of 100 km / h. The flow state was examined. The evaluation result is when a line of 5 mm grid ruled 20 x 40 squares is drawn on the surface of the sealant layer before running, the number of squares whose shape is distorted after running is counted, and no flow of the adhesive sealant material is observed ( "Good" indicates that the number of distorted cells is 0), "OK" indicates that the number of distorted cells is less than 1/4 of the total, and the number of distorted cells is 1/4 or more of the total. The case of is indicated by "impossible".

The types of raw materials used in Tables 1 and 2 are shown below.
-Chlorinated butyl rubber: JSR CHLOROBUTYL 1066
・ Natural rubber: Natural rubber manufactured by SRI TRAN ・ Carbon black: Seast KH manufactured by Tokai Carbon Co., Ltd.
・ Sulfur: Small lump sulfur manufactured by Hosoi Chemical Industry Co., Ltd. ・ Quinone Dioxime: Barnock GM manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
-Crosslinking aid: Thiram-based vulcanization accelerator, Noxeller TT-P manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
-Organic peroxide: Dibenzoyl peroxide, NOF NS manufactured by NOF CORPORATION (1 minute half-life temperature: 133 ° C)
-Liquid polymer 1: Aroma oil, Idemitsu Kosan Diana process oil AH-58 (molecular weight: 1000)
-Liquid polymer 2: Paraffin oil, Hicol K-350 manufactured by Kaneda (molecular weight: 850)
-Liquid polymer 3: Polybutene oil, Nippon Oil Polybutene HV-15 manufactured by JXTG Energy Co., Ltd. (Molecular weight: 1300)

As is clear from Tables 1 and 2, the adhesive sealant materials of Examples 1 to 5 are both immediately after production and after storage under the above-mentioned conditions when used as a sealant layer for a self-sealing type pneumatic tire. Goodly exhibited sealing property and adhesiveness. That is, the sealing property and the adhesive property could be well maintained for a long period of time. In addition, it was possible to suppress the flow of the sealant during running. On the other hand, since the adhesive sealants of Comparative Examples 1 to 4 did not contain sulfur, appropriate vulcanization was not performed, and the sealing property and adhesiveness deteriorated after storage under the above-mentioned conditions. Since the adhesive sealant materials of Comparative Examples 5 to 6 have a large viscosity difference ΔV, the sealing property and the adhesiveness deteriorated after being stored under the above-mentioned conditions. Since the adhesive sealant materials of Comparative Examples 7 to 8 contained quinonedioxime instead of sulfur, the adhesiveness could not be ensured both immediately after production and after storage under the above-mentioned conditions. The adhesive sealant material of Comparative Example 10 contains quinonedioxime instead of sulfur, and has a high viscosity V1, so that it has good sealing properties and adhesiveness both immediately after production and after storage under the above-mentioned conditions. I couldn't secure it.

1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcement layer 9 Inner liner layer 10 Sealant layer CL Tire equator

Claims (10)

An adhesive sealant material that constitutes a sealant layer arranged on the inner surface of a pneumatic tire.
It is composed of a sealant material composition in which 0.1 part by mass to 40 parts by mass of sulfur, more than 0 part by mass of a cross-linking aid and less than 1 part by mass, and 50 parts by mass or more of a plasticizer component are blended with respect to 100 parts by mass of the rubber component. ,
Immediately after vulcanization, the viscosity V1 measured under the condition of -20 ° C is 20 kPa · s or less, and immediately after vulcanization, the viscosity V2 and the viscosity V1 measured under the condition of -20 ° C after being stored in the environment of 30 ° C for 2 weeks. An adhesive sealant material having a viscosity difference ΔV with and less than 5 kPa · s. The adhesive sealant material according to claim 1, wherein the viscosity difference ΔV between the viscosity V1 and the viscosity V2 is 3 kPa · s or less. The adhesive sealant material according to claim 1 or 2, wherein 1 part by mass to 40 parts by mass of an organic peroxide is blended with 100 parts by mass of the rubber component. The adhesive sealant material according to any one of claims 1 to 3, wherein the butyl rubber is contained in an amount of 10% by mass or more based on 100% by mass of the rubber component. The adhesive sealant material according to claim 4, wherein the butyl rubber contains chlorinated butyl rubber, and the blending amount of the chlorinated butyl rubber is 5% by mass or more with respect to 100% by mass of the rubber component. The adhesive sealant material according to any one of claims 1 to 5, wherein the plasticizer component is a liquid polymer. The adhesive sealant material according to claim 6, wherein the liquid polymer is paraffin oil. The adhesive sealant material according to claim 7, wherein the paraffin oil has a molecular weight of 800 or more. The adhesive sealant material according to any one of claims 1 to 8, wherein the vulcanization is carried out under the conditions of a vulcanization temperature of 150 ° C. or higher and a vulcanization time of 5 to 60 minutes. A pneumatic tire provided with the sealant layer made of the adhesive sealant material according to any one of claims 1 to 9.

Images