JP2011006646A - Puncture sealing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a puncture sealing agent reducing viscosity at a low temperature and improving injection performance at a low temperature, as well as having excellent storage stability, initial seal performance, and seal retention performance.SOLUTION: The puncture sealing agent includes a natural rubber latex and 1,3-propanediol. Preferably, the rubber latex is a natural rubber latex.

Description

The present invention relates to a puncture sealing agent in which the viscosity of a sealing liquid at a low temperature is improved in a puncture treatment system in which a puncture sealing agent and high-pressure air are sequentially injected into a tire from an air valve of a tire wheel during tire puncture.

As a treatment system for repairing a punctured tire as an emergency, for example, a pressure vessel containing a puncture sealant and a high-pressure air source such as a compressor are used, and after the puncture sealant is injected into the tire via an air valve, the system continues. There is known one in which high-pressure air is continuously injected and the tire is pumped up to a pressure at which the vehicle can run (hereinafter sometimes referred to as an integral type) (see FIG. 1 of Japanese Patent Laid-Open No. 2001-199886). .

As such a puncture sealant, a natural rubber latex described in Patent Documents 1 to 3 is blended with a resin-based adhesive and ethylene glycol. However, puncture sealants based on natural rubber latex and added with ethylene glycol as an antifreeze agent are easy to cream for long-term storage, and there is room for improvement in the storage stability (long-term storage properties) of puncture sealants. is there.

Therefore, Patent Document 4 proposes a puncture sealing agent using propylene glycol as an antifreezing agent and having improved stability. However, the use of propylene glycol in place of ethylene glycol increases the viscosity of the puncture sealant at a low temperature, and it may be difficult to inject the puncture sealant from the air valve in a low temperature environment. Further improvements are desired for use at low temperatures. Here, it is possible to increase the fluidity of the puncture sealing agent by reducing the content of the rubber particles and the tackifying resin that are solid contents, but the puncture sealing performance is deteriorated.

JP 2002-294214 A JP 2001-198986 A JP 2000-272022 A Patent 4074073

The present invention solves the above-mentioned problems, reduces the viscosity at low temperature, improves the injectability at low temperature, has excellent storage stability, and has excellent initial seal performance and seal retention performance. An object of the present invention is to provide a puncture sealant.

The present invention relates to a tire puncture sealant containing rubber latex and 1,3-propanediol.

The rubber latex is preferably natural rubber latex or deproteinized natural rubber latex.

According to the present invention, since 1,3-propanediol is further added to the tire puncture sealant containing rubber latex, it exhibits storage stability equivalent to that when propylene glycol is used as an antifreeze agent. It is possible to provide a puncture sealant that exhibits low temperature characteristics equivalent to those obtained when ethylene glycol is used and has a good balance. At the same time, excellent initial seal performance and seal retention performance can be obtained.

The tire puncture sealant of the present invention contains rubber latex and 1,3-propanediol.

Examples of the rubber latex include natural rubber latex and synthetic rubber latex. Among them, in the present invention, the puncture sealing agent can be injected into the tire without clogging the valve, and the puncture sealing agent quickly enters the puncture hole by running, and is solidified by mechanical stimulation due to the deformation of the tire. From the viewpoint of performance such as sealing (initial sealing performance) and maintaining the sealing performance up to a certain distance (seal holding performance), a puncture sealing agent mainly composed of natural rubber latex is preferably used. .

In particular, so-called deproteinized natural rubber latex obtained by removing protein from natural rubber latex can be prevented from decaying with less ammonia, so that it prevents corrosion damage to steel cords caused by ammonia and generation of irritating odors. Can be more preferably used. Deproteinized natural rubber latex can be prepared, for example, by adding a proteolytic enzyme to natural rubber latex to decompose the protein and then washing as described in JP-A-10-217344.

On the other hand, examples of the synthetic rubber latex further include butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-vinyl acetate rubber, chloroprene rubber, vinyl pyridine rubber, butyl rubber, and modified rubber latex thereof. Natural rubber latex and synthetic rubber latex may be used alone or in combination of two or more.

The rubber latex is obtained by emulsifying and dispersing a rubber solid in a fine particle form in an aqueous medium containing a small amount of a surfactant as an emulsifier. Usually, the proportion of the rubber solid is about 60% by mass. Rubber latex is used. Moreover, it is preferable to make the compounding quantity A of rubber latex (rubber solid content) into the range of 10-40 mass% with respect to the total mass 100 mass% of a puncture sealing agent from the point of initial stage sealing performance and seal holding performance. The lower limit of the amount A is more preferably 20% by mass or more, and the upper limit is more preferably 35% by mass or less.

The puncture sealing agent of the present invention preferably contains a tackifier. The tackifier is used to enhance the adhesion between rubber latex and tire and improve the puncture sealing performance. For example, the tackifier resin is emulsified and dispersed in an aqueous medium containing a small amount of an emulsifier. A tackified resin emulsion (oil-in-water emulsion) can be used. As the tackifying resin which is a solid content of the tackifying resin emulsion, those which do not coagulate the rubber latex, for example, terpene resins, phenol resins and rosin resins can be preferably used. Other preferred resins include polyvinyl ester, polyvinyl alcohol, and polyvinyl pyrrolidine.

The blending amount B of the tackifier resin (solid content of the tackifier) is preferably 2 to 10% by mass with respect to 100% by mass of the total mass of the puncture sealing agent. The lower limit of the amount B is more preferably 4% by mass or more, and the upper limit is more preferably 7% by mass or less.

The rubber solid content A is less than 10% by weight, and the tackifier resin content B is
If it is less than 15% by mass, the puncture seal performance and the seal retention performance may be insufficient. On the contrary, if the blending amounts A and B exceed 40% by mass and 20% by mass, respectively, the storage performance is impaired such as rubber particles are likely to be aggregated during storage, and the viscosity increases and the air valve of the puncture sealing agent increases. May make it difficult to inject. Therefore, it is preferable that the sum (A + B (solid content)) of the blending amounts A and B is in the range of 15 to 60% by mass with respect to 100% by mass of the total mass of the puncture sealing agent. The lower limit of the blending amount A + B (solid content) is more preferably 30% by mass or more, and the upper limit is more preferably 50% by mass or less.

As the emulsifier for the rubber latex and the emulsifier for the tackifying resin emulsion, for example, a surfactant such as an anionic surfactant, a nonionic surfactant, and a cationic surfactant can be suitably used. The total amount of the emulsifier is about 0.4 to 2.0% by mass with respect to 100% by mass of the total mass of the puncture sealing agent.

In the present invention, 1,3-propanediol is used as the antifreezing agent. By using 1,3-propanediol instead of propylene glycol (1,2-propanediol), an increase in viscosity at a low temperature is suppressed, and the injection property of the puncture sealant at a low temperature can be improved. For this reason, the operating temperature range of the puncture sealing agent can be expanded to the low temperature side, and clogging in the valve core can be prevented when the puncture sealing agent and air are injected from the valve core even at a low temperature in the integrated type puncture treatment system. This is because in 1,3-propanediol, the hydroxyl group (—OH) is bonded to positions 1 and 3 of the carbon atom, but “1,3-” is more bipolar than “1,2-”. Since the child moment is reduced, it is assumed that the hydrogen bonding force is reduced and the viscosity can be reduced.

In addition, when an antifreezing agent is added to the puncture sealing agent, the stability of the rubber particles may deteriorate and may aggregate, but in the present invention, since 1,3-propanediol is used, it is long. When stored for a period of time, rubber particles and pressure-sensitive adhesive particles can be prevented from aggregating in the vicinity of the surface and being transformed into a cream-like substance, and excellent storage performance (storage stability) is exhibited. Therefore, the use of 1,3-propanediol can eliminate the problems when ethylene glycol is used (poor storage stability) and the problems when propylene glycol is used (poor low-temperature characteristics), and storage stability Compatibility and low-temperature characteristics. Such an effect is obtained when 1,3-propanediol is used, and problems such as thickening occur when other compounds such as butadiol are used as the antifreezing agent.

Further, by using 1,3-propanediol, a good antifreezing effect can be obtained. Furthermore, the amount used can be minimized, and adverse effects on various performances such as puncture sealing performance by the antifreezing agent can be prevented.

As for the compounding quantity C of 1, 3- propanediol with respect to 100 mass% of total mass of a puncture sealing agent, 30-60 mass% is preferable. If the blending amount C is less than 30% by mass, the increase in viscosity at a low temperature is increased. Conversely, if it exceeds 60% by mass, the solid content in the puncture sealing agent is decreased, and the puncture sealing property may be deteriorated. The lower limit of the amount C is more preferably 35% by mass or more, and the upper limit is more preferably 85% by mass or less.

The blending amount D of 1,3-propanediol is preferably 50 to 85% by mass in 100% by mass of the liquid component of the puncture sealing agent. If the blending amount D is less than 50% by mass or exceeds 85% by mass, the increase in low-temperature viscosity may increase. The lower limit of the amount D is more preferably 55% by mass or more, and the upper limit is more preferably 80% by mass or less.

The puncture sealing agent of the present invention may further contain other components as long as the effects of the present invention are not impaired.
The puncture sealant of the present invention is produced by a general method. That is, it can be produced by mixing each of the above components by a known method.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Production Example 1
Bacterial proteolytic enzyme was added to field latex (solid content 30% by mass) and allowed to stand at 40 ° C. for 24 hours to obtain a field latex subjected to proteolysis. This field latex was purified by a rotary flat membrane separator according to the method described in Japanese Patent No. 3350593, and concentrated to a solid content of 60% by mass to obtain a deproteinized natural rubber latex.

Examples 1-7 and Comparative Examples 1-4
Commercially available natural rubber latex (HA-type natural rubber latex from Malaysia: 60% by mass rubber solid content), prepared deproteinized natural rubber latex, carboxy-modified styrene-butadiene rubber (SBR) latex, or butadiene rubber (BR) latex A puncture sealant was prepared based on the specifications in Table 1.

In addition, the following were used for the carboxy modified styrene-butadiene rubber (SBR) latex, butadiene rubber (BR) latex, and tackifier.
Tackifier: terpene resin emulsion (solid content: about 50% by mass)
Carboxy-modified SBR latex: Nipol LX426 (manufactured by Zeon Corporation, solid content: about 50% by mass)
BR latex: Nipol LX111 A2 (manufactured by Nippon Zeon Co., Ltd., solid content: about 50% by mass)

About each obtained puncture sealing agent, puncture seal performance, seal retention performance, storage performance (storage stability), and low temperature viscosity (-40 degreeC) were evaluated by the following method, and the result was shown in Table 1.

(1) Punk seal performance:
A tire having a tire size of 185 / 65R14 was drilled with a nail having a diameter of 4.0 mm, and after removing the nail, 500 ml of a puncture sealing agent was injected, and the air was pressurized to 200 kPa. Thereafter, whether or not the puncture hole was closed after running for 10 minutes at a load (3.5 kN) on the drum was evaluated in two stages.

(2) Seal retention performance:
The tire was used to measure whether or not there was an air leak from a puncture hole before traveling 100 km after being sealed, and was evaluated in two stages: no air leak ... ○, air leak ... ×.

(3) Storage performance (storage stability):
500 ml of the prepared puncture sealant is stored in a bottle-shaped container, and the amount of cream-like substance produced after being stored in an oven at 80 ° C. for 2 months is measured, and the puncture sealant is measured. The mass ratio (%) relative to the whole was shown.

(4) Low temperature viscosity (−40 ° C.):
Using a B-type viscometer (Brookfield viscometer), the viscosity of the puncture sealant at −40 ° C. was measured.

As shown in Table 1, Comparative Examples 1 and 3 using propylene glycol as an antifreezing agent are inferior in low-temperature characteristics, and Comparative Examples 2 and 4 using ethylene glycol are inferior in storage performance, whereas 1,3- The puncture sealant of the example using propanediol was excellent in both of these characteristics. Moreover, it was excellent in puncture seal performance and seal retention performance.

Claims (3)

A tire puncture sealant comprising rubber latex and 1,3-propanediol. The tire puncture sealant according to claim 1, wherein the rubber latex is natural rubber latex. The tire puncture sealant according to claim 1, wherein the rubber latex is a deproteinized natural rubber latex.