JP4754900B2 - Puncture sealant - Google Patents

Description

  The present invention relates to a puncture sealing agent used when sealing a punctured tire.

  Various puncture sealing agents are known as repair agents for sealing the occurrence of puncture (see, for example, Patent Document 1). These mainly include colloidal dispersion polymers in an aqueous medium known as latex. That is, for example, polyethylene-butadiene latex, polyvinyl acetate latex, acrylic copolymer latex, nitrile latex, acrylonitrile-butadiene latex, and polychloroprene latex are used. It is also known that puncture sealants contain tetrachlorethylene as a carrier medium instead of water.

  In order to fill the internal pressure so that such a puncture sealing agent can be guided into the inside of the tire and run, an apparatus, for example, a spray can, conventionally provided with a pressure-resistant container containing a puncture sealing agent containing a liquefied gas as a pressure source has been used. Used. A propane / butane mixed gas is mainly used as the liquefied gas, but rarely a chlorofluorocarbon is also used. One end of a hose is connected to the spray can by an outlet valve, and a screw adapter for a tire valve is attached to the other end of the hose.

  When puncture occurs in the tire, the puncture sealant is blown out of the spray can through the tire valve and into the tire, and the internal pressure of the tire is increased by the fuel gas at a specific level depending on the amount of gas leakage. Refilled. At this time, although depending on the degree of damage, the tire travels several kilometers while spraying a puncture sealing agent inside the tire and sealing the damage.

  In another apparatus, the puncture sealant is housed in a compression flask connected via an adapter to a tire valve from which a valve insert has been previously extracted. The puncture sealant is blown into the tire by the compression action of the flask. After insertion of the valve insert, the tire is reinflated to a specific internal pressure with the aid of a carbon dioxide cartridge.

  By the way, the puncture sealants used are not completely satisfactory. Since they are removed mechanically relatively quickly and the speed of closing the puncture holes is slow, it takes a considerable amount of time for the preliminary run to complete the seal and allow it to run.

However, since the rate at which the latex solidifies is slow, it is necessary to travel 2 to 5 km before complete sealing, and it is necessary to replenish air with a compressor or the like when the internal pressure is greatly reduced, which is troublesome.
Japanese Patent No. 3210863

As described above, an object of the present invention is to solve the above conventional problems and achieve the following object. That is,
An object of the present invention is to provide a puncture sealing agent that can be sealed at a short distance.

As a result of intensive studies to achieve the above object, the present inventors have found that the above-described problems can be achieved by the present invention described below.
That is, the present invention
<1> A puncture sealing agent containing at least a rubber latex, a microcapsule in which an adhesive is encapsulated, and an antifreeze agent, wherein the solid content is 5 to 70% by mass, Content is 0.1-10 mass%, It is a puncture sealing agent characterized by the above-mentioned.

<2> The puncture sealing agent according to <1>, wherein the adhesive is a cyanoacrylate, epoxy, or urethane adhesive.

<3> The <1>, wherein the rubber latex is at least one selected from the group consisting of SBR latex, NBR latex, MBR latex, carboxyl-modified NBR latex, carboxyl-modified SBR latex, and NR. Or it is a puncture sealing agent as described in <2>.

  According to the puncture sealing agent of the present invention, it is possible to provide a puncture sealing agent that can be sealed with a short travel distance.

The puncture sealing agent of the present invention is a puncture sealing agent containing at least a rubber latex, a microcapsule encapsulating an adhesive, and an antifreeze agent, and the solid content is 5 to 70% by mass. The microcapsule content is 0.1 to 10% by mass.
Here, the “solid content” can be determined as follows. First, 100 g of the puncture sealing agent is allowed to stand at 200 ° C. for 30 minutes. It can be determined by measuring the mass of the residue after standing and dividing the mass of the residual by the mass of the puncture sealing agent (mass of residual amount / mass of the puncture sealing agent before leaving).

When the solid content is less than 5% by mass, the ratio of the rubber latex becomes low, and it becomes impossible to ensure sufficient sealing performance. Moreover, when it exceeds 70 mass%, characteristics other than a sealing property cannot fully be ensured.
The upper limit with preferable solid content in the said range is 60 mass%, More preferably, it is 50 mass%, More preferably, it is 40 mass%. Moreover, the minimum with preferable content of solid content in the said range is 8 mass%, More preferably, it is 10 mass%.

  In the present invention, the microcapsule bursts when passing through the puncture hole, and the adhesive component enclosed in the microcapsule pops out to solidify the adhesive, and the puncture hole is solidified and sealed. The microcapsule ruptures because the microcapsule is compressed by repeatedly contracting and expanding the puncture hole during traveling. When the adhesive solidifies, the puncture can be sealed. However, since the adhesive solidifies in a shorter time than the latex alone, it can be sealed faster than before.

  In the present invention, the content of the microcapsules is 0.1 to 10% by mass, but if the content of the microcapsules is less than 0.1% by mass, the sealing property is insufficient, and if the content is 10% by mass or more, Viscosity increases and liquid injectability decreases. The content of the microcapsule is more preferably 0.5 to 7.5% by mass, and further preferably 1 to 5% by mass.

  The particle size of the microcapsule is preferably 1 to 500 μm, more preferably 5 to 250 μm, and still more preferably 10 to 200 μm. If the particle size of the microcapsule is less than 1 μm, the microcapsule may not burst even if the puncture hole contracts, and if it exceeds 500 μm, it may not be able to pass through the puncture hole.

  The material of the capsule wall of the microcapsule is not particularly limited, but particularly suitable materials in the present invention include nitrile copolymers and formalin condensation resins.

  The adhesive encapsulated in the microcapsule is preferably a cyanoacrylate, epoxy, or urethane. Specifically, cyanoacrylate adhesives include cyanoacrylate adhesives manufactured by Sumitomo Chemical Co., epoxy systems include Cemedine manufactured by Cemedine Tsusho Co., Ltd., urethane systems include urethane resins manufactured by Mitsui Takeda Chemical Co., Ltd., and the like. . Of these adhesives, cyanoacrylate adhesives are particularly preferably used. Moreover, high adhesiveness is obtained by anionic polymerization using a small amount of water as a catalyst.

  A method for encapsulating the adhesive in a microcapsule will be described below. As the inclusion means, as seen in a general method for producing microcapsules, for example, a copolymer that becomes a component of the capsule wall, a condensed resin and an adhesive component to be included are mixed, and then a homomixer And a means obtained by polymerization in an autoclave which has been dispersed and nitrogen-substituted using a stirring means such as the above.

The viscosity of the puncture sealant is a condition assumed as an actual use condition (at 60 ° C. to −30 ° C., preferably 3 to 6000 mPa · s, more preferably 5 to 4500 mPa · s, More preferably, it is -3000 mPa * s, It is especially preferable that it is 10-3000 mPa * s, It is most preferable that it is 15-1500 mPa * s.
If it is less than 3 mPa · s, the viscosity may be too low and liquid leakage may occur during injection into the valve. If it exceeds 6000 mPa · s, the resistance during injection may become strong and the ease of injection may be reduced, and the spread to the tire inner surface may not be sufficient, and high sealing performance may not be obtained. The viscosity can be measured with a B-type viscometer or the like.

  The antifreezing agent is not particularly limited, and ethylene glycol, propylene glycol and the like can be used. The content of the antifreezing agent is preferably 5 to 50% by mass. If it is less than 5% by mass, sufficient anti-freezing properties at low temperatures may not be obtained. If it exceeds 50% by mass, the amount of glycol increases with respect to the amount of rubber latex. Due to the presence of latex particles dispersed in glycol, sufficient sealing properties may not be obtained.

  Various latexes can be used as the rubber latex, but from the viewpoint of ensuring better sealing properties, the latex is composed of SBR latex, NBR latex, MBR latex, carboxyl-modified NBR latex, carboxyl-modified SBR latex, and NR. It is preferable to use at least one selected from the group.

  The puncture sealant of the present invention can contain water for dilution. Furthermore, you may add a normal dispersing agent, an emulsifier, a foaming stabilizer, or pH adjusters, such as ammonia and caustic soda, to a puncture sealing agent. Further, as the resin adhesive, a terpene resin such as a terpene phenol resin can be used.

  As a puncture repair method using the puncture sealing agent as described above, a known method can be applied. That is, first, a container filled with a puncture sealing agent is inserted into a valve opening of a tire and an appropriate amount is injected. Thereafter, the tire may be rotated so that the puncture sealing agent spreads on the inner surface of the tire and can seal the puncture hole.

  Further, the puncture sealing agent of the present invention can be applied to puncture repair of various pneumatic tires. Examples thereof include automobile tires, motorcycle tires, unicycle tires, wheelchair tires, vehicle tires used for farmland work and garden work, and the like.

  The puncture sealant itself of the present invention described above can be introduced into the inside of a tire using various pump-up devices, for example, a spray can containing a propane / butane mixed gas as a fuel gas, and the tire can be reinflated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these.

[Examples 1 to 3 and Comparative Example 1]
The materials shown in Table 1 below were mixed into NBR rubber latex (Nipole manufactured by Nippon Zeon Co., Ltd.) to prepare puncture sealing agents according to Examples 1 to 3 and Comparative Example 1. The particle size of the microcapsules was 50 μm.

  100 g of the puncture sealing agent prepared in Examples 1 to 3 and Comparative Example 1 was collected, held at 200 ° C. for 30 minutes, and the solid content was calculated from the mass after the holding. The respective solid contents are shown in Table 1.

[Evaluation]
The produced puncture sealant was evaluated for puncture hole sealability as described below.
・ Punk sealability:
In a tire tread groove portion of one tire, a φ6 mm nail was stepped out to make a hole, and the produced puncture sealing agent was injected and attached to a car. After that, while maintaining the air pressure of 1.3 kgf / cm ² (12.74 × 10 ⁻⁴ Pa), the vehicle was run at about 50 km / h, and it was confirmed whether or not the air leakage stopped after running for 5 km. . Table 1 shows the case of being sealed as ◯ and the case of not being sealed as x.

  From the results of Table 1, in Examples 1 to 3, the travel distance until puncture sealing was reduced to 5 km or less, while in Comparative Example 1, the seal was not sealed even after 5 km travel.

Claims (3)

A puncture sealing agent comprising at least rubber latex, a microcapsule encapsulating an adhesive, and an antifreeze agent,
A puncture sealing agent having a solid content of 5 to 70 mass% and a microcapsule content of 0.1 to 10 mass%.   The puncture sealing agent according to claim 1, wherein the adhesive is a cyanoacrylate, epoxy, or urethane adhesive.   3. The rubber latex is at least one selected from the group consisting of SBR latex, NBR latex, MBR latex, carboxyl-modified NBR latex, carboxyl-modified SBR latex, and NR. Puncture sealant.