JP2003082328A - Puncture sealing agent for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rubber component from solidifying during storage and becoming a foreign matter to obstruct the injection ability and the sealing properties. SOLUTION: In a puncture sealing agent comprising a deproteinized rubber latex, one or more glycols selected from ethylene glycol, diethylene glycol and propylene glycol are used as an antifreezing agent, and the content is more than 25 wt.% and not more than 35 wt.% based on the total weight of the puncture sealing agent.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a puncture sealing agent for a tire, which prevents storage of a rubber component when a puncture sealing agent is stored for a long period of time and has improved storage performance. 2. Description of the Related Art When a puncture occurs in a tire, the applicant of the present invention has disclosed a puncture sealant which is injected into the tire and seals the puncture portion from the inside.
No. 44 proposes a deproteinized natural rubber latex containing an adhesive, an antifreezing agent, and a surfactant. [0003] Compared to a conventional puncture sealant using a non-deproteinized natural rubber latex, the sealant, liquefaction stability and spoilage resistance can be improved while suppressing the use of ammonia. This has the advantage that corrosion damage and irritating odor can be prevented from being generated on the steel cord. [0004] However, when a puncture sealant having such a composition is stored for a long period of time, the rubber component in the puncture sealant may be solidified and cannot be used as a puncture sealant. It turned out that there is. [0005] As a result of research conducted by the present inventor to determine the cause, it was found that the solidification of the rubber component was caused by freezing of the puncture sealing agent during storage. That is,
A puncture sealant is a latex in which rubber particles and pressure-sensitive adhesive particles are dispersed and suspended in an aqueous solution of an antifreezing agent due to the ion repulsion of a surfactant, but the rubber particles are bonded to each other by freezing of the aqueous solution. To solidify. Further, the rubber component once solidified does not return to its original state even when the temperature is increased and then thawed, remains as a foreign substance in the puncture sealing agent, and impairs the injection property and sealing property to the tire. Therefore, in order to prevent such solidification of the rubber component, it is essential not to freeze the puncture sealant during storage, and at least to -30 ° C., which is assumed to be the worst storage environment. It becomes important. Accordingly, the present invention relates to an improvement of the puncture sealant disclosed in the above-mentioned publication, and its object is to prevent the freezing of the puncture sealant up to -30.degree. An object of the present invention is to provide a tire puncture sealant that can suppress solidification of a rubber component therein, enhance long-term storage performance, and can be used in a low-temperature environment. [0008] In order to achieve the above object, the invention of claim 1 of the present application provides a puncture sealing agent which seals the inner surface of a tire, from natural rubber latex to rubber particles in raw rubber. The deproteinized rubber latex obtained by removing the contained protein contains an adhesive, an antifreezing agent, and a surfactant, and the nitrogen content relative to the rubber solid content of the deproteinized rubber latex is reduced. A puncture sealant having 0.1% by weight or less and an ammonia content of 0.5% by weight or less, wherein one or more glycols selected from ethylene glycol, diethylene glycol, and propylene glycol are used as the antifreezing agent, Moreover, the content of the glycol with respect to the total weight of the puncture sealing agent is set to be more than 25% by weight and 35% by weight or less. It is characterized by. The "nitrogen content" is a value measured by the Kjeldahl method.
It is a value measured by the method described in SK6381-5.3. An embodiment of the present invention will be described below. The puncture sealant of the present invention uses a deproteinized rubber latex having a nitrogen content of 0.1% by weight or less based on a rubber solid content in a low ammonia state having an ammonia content of 0.5% by weight or less. The deproteinized rubber latex contains an adhesive, an antifreezing agent, and a surfactant for stabilizing the deproteinized natural rubber latex. Here, the deproteinized natural rubber latex is a latex obtained by removing the protein contained in the rubber particles in the raw rubber from the natural rubber latex. Use less than 0.1% by weight per minute.
Incidentally, the protein content of ordinary natural rubber latex has reached about 0.2 to 0.3% by weight in terms of nitrogen content. [0012] The deproteinized natural rubber latex is formed, for example, by adding a protease to natural rubber latex to decompose the protein, followed by washing, as described in JP-A-10-217344. it can. [0013] Since the deproteinized natural rubber latex has a low protein content, it can suppress decay with less ammonia, and can prevent corrosion damage to steel cord and generation of irritating odor caused by ammonia. [0014] The puncture sealant quickly enters the puncture hole as it travels, closes the puncture hole, and maintains the sealing performance up to a certain traveling distance. The content relative to the total weight is 40 to 60% by weight. At this time, the content of the rubber solid content is at least 25% by weight based on the total weight of the puncture sealant. Next, as the pressure-sensitive adhesive, various resin-based pressure-sensitive adhesives that do not coagulate the deproteinized natural rubber latex can be used. For example, terpene resins and phenol resins can be preferably used. Other preferred resin-based adhesives include polyvinyl ester, polyvinyl alcohol, and polyvinyl pyrrolidine. The resin-based pressure-sensitive adhesive is used to enhance the adhesion between the rubber latex and the tire and to improve the sealing performance. The content of the resin-based pressure-sensitive adhesive is 10 to 10% based on the total weight of the puncture sealing agent. A range of 30% by weight is preferred. If it is less than 10% by weight, the puncture sealant will have low adhesiveness, and the sealing performance and the seal holding performance will be insufficient. Conversely, if it exceeds 30% by weight, the sealing performance will be reduced due to the relative decrease in the latex content. As the above-mentioned surfactants, anionic surfactants, amphoteric surfactants, special carboxylic acid type surfactants and the like can be used. It can be preferably used, for example, without lowering the solidification and having the effect of suppressing solidification in the valve core. Examples of the fatty acid in the fatty acid salt having 9 to 18 carbon atoms include capric acid having 10 carbon atoms, lauric acid having 12 carbon atoms, myristic acid having 14 carbon atoms, palmitic acid having 16 carbon atoms, and 18 carbon atoms. Stearic acid, oleic acid, linoleic acid, linolenic acid and the like.
On the other hand, examples of the salt include a sodium salt, a potassium salt, an ammonium salt, and a triethanolamine salt. However, among these, ammonium laurate and triethanolamine laurate, in particular, can exhibit an excellent coagulation inhibitory effect and have the property that the coagulation inhibitory effect can be improved in proportion to the content thereof. It can be used preferably. The ammonium laurate and triethanolamine laurate can be used by mixing with other surfactants. In this case, the other surfactants are those of the above-mentioned fatty acid salts having 9 to 18 carbon atoms. It is better to use The ammonium laurate has a tendency to smell ammonia because ammonia is required when forming the ammonium laurate. Therefore, from the viewpoint of smell, it is more preferable to use triethanolamine laurate. The content of the surfactant is preferably in the range of 0.4 to 2.0% by weight based on the total weight of the puncture sealing agent. It becomes insufficient and tends to solidify in the valve core. Conversely, if it exceeds 2.0% by weight, the sealing performance itself may be deteriorated. Next, one or more glycols selected from ethylene glycol, diethylene glycol and propylene glycol are used as the antifreezing agent. This is because ethylene glycol, diethylene glycol, and propylene glycol have an excellent antifreezing effect as compared with other glycols, as shown in FIG. 1 showing the relationship between the aqueous solution concentrations of various glycols and their freezing points. Because it can be demonstrated. That is, it is possible to minimize the amount of the antifreezing agent used while securing the necessary antifreezing effect, and to prevent the antifreezing agent from adversely affecting various properties such as sealing performance. From such a viewpoint, ethylene glycol and propylene glycol, which have particularly high antifreezing effects, can be preferably used. In the puncture sealant, about 40% by weight of the deproteinized natural rubber latex is water, and about 50% by weight of the adhesive is water. That is, about 30% of the usual puncture sealant
About% becomes moisture. On the other hand, as shown in FIG. 1, in the case of ethylene glycol, diethylene glycol and propylene glycol, the freezing point temperature (freezing temperature) is -3.
In order to lower the temperature to 0 ° C., the aqueous solution needs to have a concentration of about 45% or more. That is, in order for the water to be an aqueous solution having a concentration of 45% or more of ethylene glycol, diethylene glycol, and propylene glycol,
About 25% of the total puncture sealant ethylene glycol, diethylene glycol, and propylene glycol are required. Therefore, in this embodiment, the content of ethylene glycol, diethylene glycol and propylene glycol with respect to the total weight of the puncture sealant is
By setting the amount to be greater than 25% by weight and 35% by weight or less, it is possible to prevent the puncture sealant from freezing during storage and from solidifying the rubber component. Thereby, even when thawed, it is possible to prevent the solidified matter from remaining as a foreign substance in the puncture sealant and impairing the injection property and sealing property to the tire. When the content of ethylene glycol, diethylene glycol, and propylene glycol is 25% by weight or less, the storage performance is sufficiently improved by freezing in an environment up to -30 ° C. to cause solidification of the rubber component. Can not. On the other hand, if the content exceeds 35% by weight, the latex content is relatively reduced, so that the sealing performance is lowered. Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment, but can be implemented in various forms. As described above, the present invention provides a puncture sealant using a deproteinized rubber latex in which a predetermined amount of an antifreezing agent selected from ethylene glycol, diethylene glycol and propylene glycol is blended. Therefore, storage performance can be improved, and it is possible to prevent solidification of a rubber component during storage and prevent foreign matters from impairing injectability and sealability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between aqueous solution concentrations of various glycols and their freezing point temperatures.

Claims (1)

Claims: 1. A puncture sealing agent for sealing the inner surface of a tire is adhered to a deproteinized rubber latex obtained by removing a protein contained in rubber particles in raw rubber from natural rubber latex. And a nitrogen content of 0.1% by weight or less and an ammonia content of 0.5% by weight or less based on the rubber solid content of the deproteinized rubber latex. A puncture sealant, wherein one or more glycols selected from ethylene glycol, diethylene glycol, and propylene glycol are used as the antifreeze, and the content of the glycol relative to the total weight of the puncture sealant is 25.
A puncture sealant for a tire, wherein the amount is greater than 35% by weight and greater than 35% by weight.