JPS627236B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a puncture sealing composition, and more particularly to a puncture sealing composition suitable as a puncture prevention material for tubeless tires. In general, tubeless tires do not easily fall out even if a nail or the like pierces them, so there is no sudden drop in air pressure, and they are said to be relatively safe against punctures. However, in reality, if you drive for a long time, especially at high speeds, with a nail stuck in it, the centrifugal force makes it easier for the nail to come off. It becomes a dangerous situation. To prevent such risks,
It is important to maintain conditions such that sudden air leakage does not occur due to nails or the like coming off while the vehicle is running. For this reason, various attempts have been made to prevent air leakage inside the tire and maintain safe running of the vehicle by applying a sealing composition to the inner surface of the tire and immediately sealing the puncture area due to a nail or the like. ing. For example, melting point 10
A method in which polyisobutylene is added to coal tar pitch or petroleum pitch at a temperature of ℃ or above, heated and melted, and then applied to the inside of the tire crown (Japanese Patent Publication No. 31-9489), adhesive rubber is pasted inside the crown, and stockinette is applied on top of it. A method of attaching a piece of breathable fabric such as cloth (Japanese Patent Publication No. 35-17402), a sticky substance made by adding polybutene, process oil, etc. to butyl rubber and partially causing weak crosslinking is formed into a honeycomb shape. A method of forming a puncture prevention layer by filling the compartments (Japanese Patent Publication No. 34-1095), or a method of adding pulverized urethane foam, short fibers such as vinylidene chloride, and methyl cellulose to rubber latex, alcohol, and ethylene glycol. (Tokuko Showa 39-
(Japanese Utility Model Publication No. 18744), a liquid mixture of emulsion containing vinyl acetate and acrylic acid ester as main components and rubber particles, such as old tire particles (Utility Model Publication No. 1974-7442), foam liner layer and adhesive. (Japanese Patent Publication No. 50-21402), ethylene-propylene rubber mixed with polybutene and filler (Japanese Patent Publication No. 50-39453), and styrene-butadiene copolymer randomly mixed with water. mixed with aromatic oil and rosin resin (Japanese Patent Publication No. 51-5433),
Depolymerized natural rubber or synthetic rubber mixed with a large amount of highly compatible oil and then partially crosslinked (Japanese Patent Publication No. 1983-4801), butyl rubber and liquid rubber (butyl rubber) with carbon black, polybutene, and water. A method has been proposed in which solution-polymerized styrene-butadiene rubber and a crosslinking agent are dissolved in a solvent, and the two parts are mixed during spraying to crosslink (Japanese Patent Application Laid-Open No. 10354/1983), but none of these methods The sealing composition tends to migrate and concentrate in the center of the crown due to centrifugal force during high-speed driving, and safety and work environment problems arise due to the large amount of solvent used. Hot,
It has drawbacks such as being virtually impossible to mold and having insufficient sealing properties. Therefore, an object of the present invention is to eliminate the drawbacks of the conventional puncture seal compositions described above, and to provide a puncture seal that has excellent sealing properties and is easy to apply when applied to the inner surface of a tubeless tire as a puncture prevention layer. An object of the present invention is to provide a composition. The puncture seal composition according to the present invention comprises (a) a butyl rubber emulsion, (b) at least one of a diene-based unsaturated hydrocarbon polymer emulsion (hereinafter referred to as diene-based rubber emulsion) and natural rubber latex, and (c) a saturated At least one type of hydrocarbon polymer emulsion, (d) a crosslinking agent, and (e) a crosslinking initiator are combined into the above component (a).
Solid content of component (b) 5 parts by weight per 100 parts by weight of solid content of
The solid content of component (c) is 50 to 500 parts by weight per 100 parts by weight of solid content of components (a) and (b). The butyl rubber emulsion in the sealing composition of the present invention is an emulsion of a rubber component included in generally known butyl rubber, and specifically, isobutylene-isoprene copolymer or the copolymer is partially halogenated, for example, chlorinated. A brominated product is usually used, which is then emulsionized using a surfactant. Such a butyl rubber emulsion preferably has a total solid content of 60% by weight or more, and a total solid content less than this is not so preferred because a large amount of thermal energy is required to volatilize water after application. The diene rubber emulsion in the sealing composition of the present invention has good compatibility with the butyl rubber emulsion, and is further crosslinked with a crosslinking agent and a crosslinking initiator to form a three-dimensional structure.
Such diene rubbers include polyisoprene,
Examples include polybutadiene, styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), ethylene-propylene-diene copolymer (EPDM), and derivatives thereof. For example, polyisoprene emulsion is produced by dissolving polyisoprene with a large number of cis-1,4 bonds in a solvent such as toluene, which has been polymerized with an organometallic catalyst in a solution, and then producing an anionic, cationic, or nonionic emulsion using a conventional method. The polymer is dispersed into as fine particles as possible using a surfactant at a suitable temperature with gradual addition of water in a high-intensity mixing device such as a Baker Perkins type mixer with a thermal jacket of steam or hot water. It can be prepared by emulsion-forming the emulsion, and then removing the solvent such as toluene using a method such as vacuum distillation. In addition to polyisoprene, styrene,
One or more types of vinyl monomers such as vinyl acetate, acrylic acid, methacrylic acid and their esters, acrylonitrile, etc. (for example, 10% or less based on isoprene or polyisoprene,
Polyisoprene derivatives that have been copolymerized or graft polymerized to increase the strength or adhesiveness of the sealant can also be made into emulsions in the same manner. Regarding the other diene rubbers mentioned above, polymers obtained by solution polymerization, such as polybutadiene with many cis bonds, 1,2-polybutadiene, styrene-polybutadiene copolymers, such as styrene-butadiene copolymers, are mixed with maleic anhydride, etc. Modified styrene-butadiene copolymer derivatives, ethylene-propylene-diene copolymers, etc. can also be made into emulsions in the same manner as polyisoprene. On the other hand, diene rubber obtained by emulsion polymerization, such as random polybutadiene,
Styrene-butadiene copolymer, such as a styrene-butadiene copolymer derivative obtained by copolymerizing a small amount of vinylpyridine with a styrene-butadiene copolymer;
Acrylonitrile-butadiene copolymer and the like can be used by increasing the solid content concentration by an appropriate method. Natural rubber can also be used by concentrating ordinary latex. Such diene rubber emulsion and natural rubber latex have a solid content concentration of
A total solid concentration of 60% by weight or more is preferable, and a total solid content concentration of less than 60% by weight is not so preferable since a large amount of thermal energy is required to volatilize water after application. The diene rubber emulsion and natural rubber latex can be mixed with the butyl rubber emulsion in any proportion, but considering the sealing properties when used as a sealant, diene rubber or natural rubber latex can be mixed with 100 parts by weight of butyl rubber solid content. Solid content of rubber is 5 to 150 parts by weight, preferably 20 to 100 parts by weight.
Use within the range of parts by weight. If the blending amount of these diene rubbers and natural rubber is less than 5 parts by weight (solid content) per 100 parts by weight of butyl rubber, the unsaturated bond content of butyl rubber is small (excluding liquid butyl rubber, the unsaturated bond content is (usually 2% or less), even if a crosslinking agent is used, it can be used at low temperatures (e.g., temperatures below about 60°C) for short periods of time (e.g., about
Under crosslinking reaction conditions (within 30 minutes), practically sufficient strength and gelation rate cannot be obtained, and furthermore, the three-dimensional crosslinking density due to crosslinking is insufficient, so the "sag" and flow phenomena at high temperatures cannot be completely eliminated. So I don't like it. That is, by blending natural rubber or diene rubber containing many unsaturated bonds with butyl rubber and co-crosslinking it, the three-dimensional density can be increased and the above properties can be improved. On the other hand, if the blending amount of the diene rubber and natural rubber exceeds 150 parts by weight, the air permeation resistance and sealing properties of the resulting sealant layer will decrease, which is not preferable. The diene rubber emulsion must be of the same type as the butyl rubber emulsion, depending on whether it is an anionic, cationic or nonionic emulsion. When mixing natural rubber latex, since the pH of natural rubber latex is usually on the alkaline side, it is preferable to use an anionic or nonionic butyl rubber emulsion, but even a cationic butyl rubber emulsion is stable even when mixed with natural rubber latex. Some products may not become gel-like. The saturated hydrocarbon polymer emulsion in the seal composition of the present invention has a number average molecular weight of 500 obtained by polymerizing a monoolefin having 4 to 6 carbon atoms.
Emulsions of ~100,000 polymers can be suitably used. Examples of such polymers include polybutene obtained by polymerizing isobutene, polyisobutylene obtained by polymerizing isobutylene, polypentenes obtained by polymerizing one or more types of pentenes, and one or more hexenes. It includes polyolefins obtained by copolymerizing polyhexenes obtained by polymerizing the above or monoolefins having 4 to 6 carbon atoms. These polyolefins are liquid or semi-solid at room temperature and serve as a tackifier in sealants. The number average molecular weight of the saturated hydrocarbon polymer (
n) is preferably 500 to 100,000. This is because if the molecular weight is less than 500, the polymer migrates from the sealant layer into the adjacent contact material after being applied to the tire, resulting in a loss of the initial desired sealant properties, such as self-sealing properties, and an increase in modulus. If this occurs and the molecular weight exceeds 100,000, the rubber elasticity will become strong, the adhesiveness will be lost, and the sealing performance will deteriorate, which is not preferable. These polymers can be made into emulsions using surfactants in the same way as the diene rubbers mentioned above, but in this case, since their molecular weight is small, it is not necessarily necessary to use a solvent, and it is easy to emulsion them at high concentrations. Emulsions can be prepared. Such saturated hydrocarbon polymer emulsions may be used alone, or two or more types may be mixed as appropriate. The total solid content of the saturated hydrocarbon emulsion is also preferably 60% by weight or more, as in the butyl rubber emulsion. In this case as well, it is necessary that the diene rubber emulsion or natural rubber to be mixed be adapted to the pH of the butyl rubber emulsion and the type of emulsion such as anionic, cationic, or nonionic. The saturated hydrocarbon polymer emulsion can be mixed in any proportion to the total solid content (hereinafter referred to as rubber component) of the butyl rubber emulsion, diene rubber emulsion, and natural rubber latex; Considering properties and sealability, it is preferable to mix saturated hydrocarbon polymer emulsion in a solid content of usually 50 to 500 parts by weight, more preferably 80 to 200 parts by weight, per 100 parts by weight of the rubber component. Although a mixture of at least one of the butyl rubber emulsion, the diene rubber emulsion, and natural rubber latex, and at least one of the saturated hydrocarbon polymer emulsion alone can be applied as a sealant layer, usually, the double bonds in the rubber component are It is partially crosslinked by crosslinking or hydrogen abstraction crosslinking of α-methylene groups to form a three-dimensional structure. As the crosslinking agent in the sealing composition of the present invention, generally known crosslinking agents for butyl rubber or crosslinking agents for diene rubber can be appropriately selected and used. However, the crosslinking of the sealing composition of the present invention occurs at room temperature to 70°C.
It is preferable to perform the crosslinking under mild conditions of about 0.degree. C., both from the viewpoint of the manufacturing process and the quality of the product, and therefore crosslinking means known as quinoid crosslinking or resin crosslinking are particularly preferably used. In the case of quinoid crosslinking, paraquinone dioxime or paraquinone dioxime dibenzoate is used as a crosslinking agent, and an organic peroxide or an inorganic peroxide is used as a crosslinking initiator. Suitable organic peroxides include benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl peroxybenzoate, bis(p-monomethoxybenzoyl) peroxide, bis(p-nitrobenzoyl) peroxide. ,2,5-dimethyl-2,5
-Bis(benzoylperoxy)hexene, cumene hydroperoxide, t-butyl hydroperoxide, etc. are used, and hydrogen peroxide can also be used. Examples of inorganic peroxides include metal peroxides that do not react with water, such as manganese peroxide and lead peroxide. In the case of resin crosslinking, an alkylphenol resin is used as a crosslinking agent, and stannous chloride or stannic chloride is used in combination as a crosslinking initiator. The amount of these crosslinking agents and crosslinking initiators used depends on the amount of unsaturated bonds or the amount of α-methylene groups in the rubber component in the seal composition of the present invention. Therefore, according to the usual crosslinked polymer production method, taking into account the degree of unsaturation of the butyl rubber used, the degree of unsaturation of natural rubber and diene rubber, the amount of α-methylene groups, and the blending ratio of these rubber components, etc. The amounts of the crosslinking agent and crosslinking initiator used can be selected as appropriate. If the amount of these crosslinking agents used is too low, the crosslinking density will be low, resulting in problems such as a lack of sealing performance at high temperatures or the sealant flowing during high-speed driving.On the other hand, if the amount of crosslinking agent is too large, the crosslinking density will be high. If it becomes too large, the modulus becomes too large and it cannot function as a sealant. For example, in the case of quinoid crosslinking, the rubber component
1 to 15 quinone dioximes per 100 parts by weight
It is appropriate to use the peroxide in an amount of 3 to 10 parts by weight, preferably 3 to 10 parts by weight, and the peroxide is usually used in an amount of 0.5 to 1.5 equivalents per equivalent of quinone dioxime. The stoichiometric reaction amount of peroxide per 1 equivalent of quinone dioxime is 1 equivalent, but in reality, it is within the above range considering the dispersibility and solubility of the crosslinking agent and crosslinking initiator in the emulsion. decided on. If there is too little crosslinking initiator, the crosslinking reaction will not take place effectively no matter how much crosslinking initiator there is.On the other hand, if there is too much crosslinking initiator, for example, excess peroxide may cause further deterioration of butyl rubber or other diene rubbers. It is undesirable because it may be involved in crosslinking. In the case of resin crosslinking, for example, the amount of alkylphenol resin used is within the range of 1 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the rubber solid content, as in the case of quinoid crosslinking. It is preferred that the proportion of stannous chloride or stannic chloride used at the same time be within the range of 3:1 to 10:1 to the alkylphenol resin. The sealing composition of the present invention may also contain inorganic fillers, such as anhydrous silicic acid, hydrated silicic acid, clay, talc, mica, calcium carbonate, alumina, titanium white, carbon black, and cellulose microcrystals. By blending, it is possible to increase the total solid content concentration of the emulsion, prevent sag and flow immediately after spraying and coating, and improve the heat resistance of the crosslinked product. Further, it is also possible to use an anti-sagging agent (thixotropic agent) for the sole purpose of preventing dripping. The amount of the inorganic filler is usually preferably 50 parts by weight or less per 100 parts by weight (solid content) of the emulsion; if more than 50 parts by weight is added, sealing properties tend to be impaired. The sealing composition of the present invention is usually used by spraying or applying it to the surface to be sealed, that is, the inner surface of a tire, etc., but in order to create a more preferable usage condition, it is necessary to add a crosslinking agent to a butyl rubber or diene rubber emulsion. It is preferable to prepare a mixed system and a system in which a crosslinking initiator is mixed with a saturated hydrocarbon polymer emulsion, and to mix the two immediately before use. When a crosslinking initiator such as peroxide or tin chloride is added to a rubber emulsion, it interacts with the double bond in the rubber molecule and the hydrogen of the α-methylene group to induce a crosslinking reaction, resulting in a crosslinking reaction over time. This tends to cause an increase in viscosity and reduce workability during spraying and application. On the other hand, even if a crosslinking initiator is added to a saturated hydrocarbon emulsion, the above-mentioned change over time does not occur. On the other hand, even if a crosslinking agent such as paraquinone dioxime or alkylphenol resin is added to a rubber emulsion, a crosslinking reaction will not occur unless a crosslinking initiator is present. Therefore,
If a system in which a crosslinking agent is mixed with a rubber emulsion and a crosslinking initiator in a saturated hydrocarbon polymer emulsion are prepared separately, and the two are mixed at the time of use, the viscosity will increase before spraying or application. without causing quality changes that affect workability such as
A high-performance sealing layer can be easily formed. When mixing the two components, it is of course not a problem to mix the saturated hydrocarbon polymer emulsion in the rubber emulsion in advance without an initiator. When applying the sealing composition of the present invention to the surface to be sealed, for example, the inner surface of a tire as a puncture prevention layer, as described above, the entire composition is mixed and adjusted immediately before use, and this is applied by spraying or coating. After applying it to the designated area, leave it or store it at 60-70℃.
It is preferable to volatilize moisture and induce a crosslinking reaction by heating to a certain degree. The sealing layer thus formed has high elongation and self-sealing properties, and is highly effective as a puncture prevention material for tubeless tires, ensuring safe running of vehicles, and is also effectively used as a sealing material for civil engineering and construction. Ru. The present invention will be explained in more detail with reference to Examples below. Unless otherwise specified in the examples, "part"
and "%" represent "part by weight" and "% by weight", respectively. Example 1 Butyl rubber emulsion (trade name Exxon
Butylatex100, solids content 62%, viscosity 3500cps (25
)) and 100 parts of polyisoprene emulsion (second
(See Table Note 2) and add paraquinone dioxime (trade name, Actor Q, manufactured by Kawaguchi Chemical Co., Ltd.) to this mixture.
5 parts were predispersed. On the other hand, 20 parts of carbon black (SRF) and 8.4 parts of benzoyl peroxide were added to 100 parts of polybutene emulsion (see note 11 in Table 2) and uniformly dispersed. These two types of emulsions were evenly applied to the inner surface of a steel tire that had been molded using a spray machine equipped with a two-component static mixer, and then the surface was coated with hot air (approx.
℃) to form a sealant layer approximately 2.5-3 mm thick. The physical properties of this sealer layer are the second
As shown in the table. Tests were conducted on this tire mounted on a rim and filled with air at a pressure of 1.9 kg/cm ² . 60 nails with a diameter of 6 mm and a length of about 90 mm are attached to a pressurized tire.
After a book was driven through the hole, 20 nails were removed at a time and the changes in air pressure were measured. Five tires were used under the same test conditions. The places where it was driven were the crown and shoulder of the tire. The results are shown in Table 1.

[Table] After running the tire on a steel drum for 2 hours at a speed of 80 km/hr with a nail driven into the tire, the speed was increased to 120 km/hr.
hr and ran for 30 minutes, then ran at 128 km/hr for 30 minutes, increasing the speed at 30 minute intervals and then at 8 km/hr intervals until the nail came out due to centrifugal force. As a result, all nails came out within the range of 130Km/hr to 160Km/hr, although this varied depending on the tire. Immediately after the tire came out, the drum was stopped and the tire air pressure was measured to check for leaks. All of the five tires tested were satisfactory, with no drop in air pressure. Also, when looking at the sealant layer after running, there was no movement of the sealant layer in the shoulder area, and there was a large difference compared to the unvulcanized one. Examples 2 to 21 Sealants were prepared using the combinations shown in Table 2, applied to tires, and tested in the same manner as in Example 1. In both cases, there was no drop in air pressure and no flow of sealant.

【table】

【table】

【table】

【table】

[Table] Examples 22 to 27 Etsuobutyl HT (trade name) (chlorinated butyl rubber, manufactured by Etsuo Chemical) was swollen and dissolved in toluene to give a solid content concentration of about 70%. This was made into an emulsion in the same manner as the polyisobutylene emulsion (see Note 14 in Table 2), and the toluene was removed under reduced pressure. The total solids content of the resulting chlorinated butyl rubber emulsion was 63%. In the same manner, an emulsion of brominated butyl rubber (trade name: Polyserbrombutyl X-2, manufactured by Polysar) was prepared. Add these emulsions to the third
The formulations shown in the table were used.

[Table] Place the obtained two emulsion liquids into tanks equipped with circulation pumps and keep them warm at approximately 70°C. If necessary, switch the discharge valve of the circulation pump and pass them through a static mixer to a steel tire. was applied to the inner surface of the These two emulsion liquids are sprayed onto the inner surface of the tire at an appropriate mixing ratio, and if the crosslinking initiator is active, they will not flow along the inner wall surface of the tire.
A very smooth surface is obtained. Unlike conventional methods that use organic solvents such as n-hexane, the installation method is simple and safe, and there is no risk of fire or explosion. The resulting sealant layer is approximately 3.0mm thick, and the tire is made into a product after going through a drying process. Static and dynamic tests were conducted on this tire in the same manner as in Example 1, and the puncture sealing properties were all the same as in Example 1. Comparative example Polyisobutylene (Vistanetx MML)
80Exxon Chemical) 20 parts of polybutene HV-1900
(manufactured by Nisseki Chemical Co., Ltd.) and 15 parts of silicic anhydride were added, heated to lower the viscosity, and then hot-sprayed at about 90°C and applied to the inner surface of the tire, and the same test as in Example 1 was conducted. In the static test, all seals were good, but in high-speed performance, one out of five tires did not seal, resulting in a drop in air pressure. Furthermore, after high-speed driving, the sealant was concentrated in the center of the tire's crown due to centrifugal force and a decrease in viscosity, and there was no sealing performance in the shoulder area or in areas where the sealant was thin. Examples 28-33 Sealants made from puncture seal compositions prepared by blending butyl rubber emulsions with other diene rubber emulsions (see Table 4 for formulations) were tested. A sealant having the composition shown in Table 4 was applied uniformly to the inner surface of steel tires in the same manner as in Example 1, and the tires were rotated in an atmosphere of 100°C and 120°C for 10 hours to observe the flow of the sealant. A tire sealing test was conducted. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. (a) butyl rubber emulsion; and (b)
(c) at least one of diene-based unsaturated hydrocarbon polymer emulsion and natural rubber latex;
At least one type of saturated hydrocarbon polymer emulsion, (d) a crosslinking agent, and (e) a crosslinking initiator are added in an amount of 5 to 150 parts by weight of the solid content of component (b) per 100 parts by weight of the solid content of component (a). A puncture seal composition comprising 50 to 500 parts by weight of component (c) as solids per 100 parts by weight of solids of components (a) and (b). 2. Claim 1, wherein the diene-based unsaturated hydrocarbon polymer is polyisoprene, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene-diene copolymer, and derivatives thereof. The puncture seal composition described in Section 1. 3. The number average molecular weight of the saturated hydrocarbon polymer obtained by polymerizing a monoolefin having 4 to 6 carbon atoms.
Claim 1, which is a polymer of 500 to 100,000
The puncture seal composition described in Section 1.