JP4862426B2 - Tire puncture sealant - Google Patents

Description

  The present invention relates to a tire puncture seal material.

Conventionally, as a tire puncture sealing material for repairing a punctured tire, a natural rubber latex blended with a tackifying resin emulsion and an antifreezing agent has been frequently used (for example, see Patent Documents 1 and 2).
This tire puncture sealant is a latex in which natural rubber particles and tackifying resin particles are repelled by ionic repulsion in an aqueous solution of an antifreeze and dispersed.
As this type of tire puncture sealant, for example, “a puncture sealant for a tire containing at least a natural rubber latex, a tackifying resin emulsion and an antifreezing agent, wherein the solid content A of the natural rubber latex and the tackifying resin are used. The solid content A of the natural rubber latex is 30 to 60 parts by weight with respect to 100 parts by weight of the total solids, which is the sum A + B + C of the solids B of the emulsion and the cryoprotectant C. The content of component B was 10 to 30 parts by weight, the content of the antifreezing agent C was 20 to 50 parts by weight, and an aromatic modified terpene resin was used as the tackifying resin of the tackifying resin emulsion A tire puncture sealant characterized by the above is known (see Patent Document 1).

  In addition, tire puncture seal materials using synthetic rubber latex such as acrylonitrile-butadiene rubber (NBR) latex and styrene-butadiene rubber (SBR) latex have been proposed (see Patent Documents 3 to 4).

  The tire puncture sealing material as described above is usually injected into the tire from the air filling portion of the tire, filled with air to a predetermined air pressure, and then traveled to reach the puncture hole. And the aggregate of rubber particles is formed by the compressive force and shearing force received when the tire is in contact with the rotation, and the puncture hole is sealed.

  The tire puncture frequency that has been used recently is usually said to be once every few years, and the frequency with which the sealant is actually used is very low. For this reason, the tire puncture sealant has not only excellent sealing performance but also performance that can withstand long-term storage in the vehicle.

JP 2004-035867 A Japanese Patent No. 3210863 JP 2005-170973 A JP 2001-62934 A

However, the natural rubber latex tire puncture seal materials described in Patent Documents 1 and 2 have low storage stability, and, for example, have a life of about one year when left in an automobile trunk, and if that is exceeded, There are problems such as solidification or gelation, and the fluidity is remarkably lowered, making it impossible to inject into a punctured tire.
Natural rubber latex tire puncture seal materials usually have an irritating odor because ammonia is used to stabilize the natural rubber latex. Furthermore, since the pH is adjusted to about 9.0 to 12.0, there is a problem that the steel cord in the tire is corroded by rust, and may cause inflammation when touching the skin.
On the other hand, Patent Document 1 describes that if so-called deproteinized natural rubber latex is used, the decay of natural rubber latex can be suppressed with less ammonia. However, the problem of odor and corrosion of steel cords remains even when deproteinized natural rubber latex is used. In addition, complicated manufacturing processes such as deproteinization are required.

Although the NBR latex tire puncture sealant described in Patent Document 3 is excellent in storage stability, it has a relatively high viscosity, so that a load is applied to the pump when it is injected into the tire, or it remains in the nozzle after the injection. There is a risk that the tire puncture sealant will harden and become clogged. Furthermore, when the temperature is extremely low, such as during the severe cold season or during snowfall, the viscosity becomes higher and the above-mentioned problem is likely to occur when injecting. In addition, since ammonia is usually adjusted to pH 9.0 to 11.0 for stabilization of NBR latex, as with natural rubber latex tire puncture seal materials, generation of irritating odors, steel cord There are problems such as corrosion and irritation when touching the skin.
In addition, since the SBR latex tire puncture sealant is also adjusted to pH 9.0 to 11.0 using ammonia for stabilization, there is a problem similar to that of the NBR latex tire puncture sealant.

Accordingly, an object of the present invention is to provide a tire puncture sealant having a sealing property equivalent to that of a conventional tire puncture sealant, having a relatively low viscosity and less odor.
Another object of the present invention is to provide a tire puncture sealing material that is also excellent in storage stability.

The inventor of the present invention is a tire puncture sealant containing a chloroprene emulsion and an antifreezing agent and having a hydrogen ion index of less than 9.0. It was found that the tire puncture sealant has a low viscosity and low odor. The inventor has also found that the tire puncture sealant has excellent storage stability when the hydrogen ion index is 7.5 or more.
The present inventor completed the present invention based on these findings.

That is, the present invention provides the following (1) to (8).
(1) A tire puncture sealant containing a chloroprene emulsion and an antifreezing agent and having a hydrogen ion index of less than 9.0.
(2) The tire puncture sealant according to the above (1), which has a hydrogen ion index of 7.5 or more.
(3) The tire puncture sealing material according to (1) or (2), wherein the antifreezing agent is contained in an amount of 100 to 400 parts by mass with respect to 100 parts by mass of the solid content of the chloroprene emulsion.
(4) The tire puncture sealing material according to any one of (1) to (3), further containing a tackifier.
(5) The tire puncture sealant according to (4), wherein the tackifier is an emulsion obtained by emulsifying a resin.
(6) The tire puncture seal material according to (4) or (5), wherein the tackifier includes at least one selected from the group consisting of a rosin resin, a terpene resin, and a hydrogenated terpene resin.
(7) The tire puncture seal according to any one of (4) to (6), wherein the solid content of the tackifier is 50 to 250 parts by mass with respect to 100 parts by mass of the solid content of the chloroprene emulsion. Wood.
(8) The tire puncture sealant according to any one of (1) to (7), wherein the hydrogen ion index is lowered by an acid.

The tire puncture seal material of the present invention has a sealing property equivalent to that of a conventional tire puncture seal material, has a relatively low viscosity, and has a low odor.
Further, when the tire puncture sealant has a hydrogen ion index of 7.5 or more, the tire puncture sealant is excellent in storage stability and can be stored in the automobile for a long time.
Furthermore, when the hydrogen ion index is 5.5 to 8.5, rust is hardly generated on the steel cord of the tire.

Hereinafter, the present invention will be described in more detail.
The tire puncture seal material of the present invention is a tire puncture seal material containing a chloroprene-based emulsion and an antifreezing agent and having a hydrogen ion index (pH) of less than 9.0.

The chloroprene emulsion used for the tire puncture seal material of the present invention is not particularly limited, and a conventionally known chloroprene emulsion can be used.
Examples of the chloroprene emulsion include emulsion polymerization of a chloroprene monomer and a vinyl monomer having an anionic group, and, if necessary, other copolymerizable ethylenically unsaturated monomers. Suitable examples are listed.

  Here, the “anionic group” refers to a group that can be negatively charged by neutralization with a base. Specifically, for example, a carboxy group, a sulfo group, a phosphoric acid group and the like are preferable. In particular, a carboxy group is more preferable.

Specific examples of the vinyl monomer having an anionic group include unsaturated fatty acids such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, and styrene sulfonic acid. These may be used alone or in combination of two or more. Of these, methacrylic acid is preferred.
0.1-20 mass parts is preferable with respect to 100 mass parts of chloroprene monomers, and, as for the usage-amount of the vinyl monomer which has the said anionic group, 1-15 mass parts is more preferable.

Specific examples of the copolymerizable ethylenically unsaturated monomer include ethylene, styrene, methyl methacrylate, acrylonitrile, 2,3-dichlorobutadiene, 1-chlorobutadiene, and the like.
The amount of the copolymerizable ethylenically unsaturated monomer is preferably 20 parts by mass or less with respect to 100 parts by mass of the chloroprene monomer.

The emulsion polymerization can be carried out by a known method, and specifically, for example, a method of polymerizing by mixing water, each of the above monomers, an emulsifying dispersant, a polymerization initiator, a chain transfer agent and the like. It is done. Furthermore, a polymerization terminator may be added when a predetermined conversion rate is reached.
The polymerization temperature can usually be carried out in the range of 0 to 80 ° C, and preferably in the range of 5 to 50 ° C.

The emulsifying dispersant is not particularly limited, and known ones can be used, and specific examples include alkali metal salts of rosin acid, sulfonic acid type, sulfuric acid ester type anionic emulsifiers, nonionic emulsifiers, and the like. . More specifically, for example, alkyl sulfonate, alkyl aryl sulfonate, alkyl sulfate, alkyl aryl sulfate, condensate of sodium naphthalenesulfonate and formaldehyde, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol, Examples include sorbitan fatty acid esters and polyoxyethylene acyl esters.
When emulsion polymerization of a chloroprene monomer and a vinyl monomer having a carboxy group is carried out under acidic conditions, alkali metal salts and triethanolamine salts of alkyldiphenyl ether disulfonic acid, alkali metal salts of dodecylbenzenesulfonic acid and triethanol Amine salts, alkali metal salts of lauryl sulfate, triethanolamine salts, and the like are preferably used.

  The addition amount of the emulsifying dispersant is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the charged monomer from the viewpoint that the emulsion polymerization can be stably performed.

Examples of the polymerization initiator include known free radical-generating substances, specifically, persulfates such as potassium persulfate and ammonium persulfate; inorganic or organic peroxidations such as hydrogen peroxide and t-butyl hydroperoxide. Thing etc. are mentioned.
Specific examples of the chain transfer agent include alkyl mercaptans, halogenated hydrocarbons, alkyl xanthogen disulfides, and sulfur.

  Specific examples of the polymerization terminator include phenothiazine, 2,6-t-butyl-4-methylphenol, and hydroxylamine.

In order to improve the stability of the chloroprene-based emulsion, it is preferable to add an emulsion dispersant in addition to the emulsion dispersant used during emulsion polymerization.
The timing of adding the emulsifying dispersant includes a method of batch addition at the time of polymerization preparation, a method of addition during polymerization, and a method of addition at the end of the polymerization. Although there is no particular limitation, the conversion rate is 50 to 90% during the polymerization. It is preferable to add at the time of reaching.

Next, the antifreezing agent will be described.
Specific examples of the antifreezing agent used in the tire puncture seal material of the present invention include, for example, ethylene glycol and propylene glycol. These may be used alone or in combination of two or more.

The content of the antifreezing agent is preferably 100 to 400 parts by mass with respect to 100 parts by mass of the solid content of the chloroprene-based emulsion from the viewpoint that the tire puncture sealant can be prevented from freezing and maintain stability. -350 mass parts is more preferable, and 140-350 mass parts is still more preferable.
Here, the solid content of the chloroprene-based emulsion means the total of the components contained in the chloroprene-based emulsion excluding water and the solvent.

The tire puncture sealant of the present invention preferably further contains a tackifier from the viewpoint that excellent sealing properties can be obtained.
Specific examples of the tackifier include rosin resins such as rosin esters, polymerized rosin esters, and modified rosins; terpene resins such as terpene phenols and aromatic terpenes; hydrogenated hydrogenated terpene resins. Examples include terpene resins; phenol resins; xylene resins. In addition, an emulsion obtained by emulsifying these resins is one of preferred embodiments from the viewpoint of excellent compatibility with the chloroprene emulsion. These may be used alone or in combination of two or more.
Among these, a tackifier containing at least one selected from the group consisting of rosin-based resins, terpene-based resins, and hydrogenated terpene-based resins is preferable from the viewpoint of excellent sealing properties.

The content of the solid content of the tackifier is preferably 50 to 250 parts by mass and more preferably 70 to 180 parts by mass with respect to a total of 100 parts by mass of the solid content of the chloroprene emulsion from the viewpoint of excellent sealing properties. Preferably, 70 to 150 parts by mass is more preferable.
Here, the solid content of the tackifier means the total of the components contained in the tackifier excluding water and the solvent.

  In addition to the components described above, the tire puncture seal material of the present invention is optionally filled with a filler, an anti-aging agent, an antioxidant, a pigment (dye), a plasticizer, a thixotropic agent, an ultraviolet absorber, a flame retardant, Various additives such as a dispersant, a dehydrating agent, and an antistatic agent can be contained.

  Examples of the filler include organic or inorganic fillers having various shapes. Specifically, for example, fumed silica, calcined silica, precipitated silica, ground silica, fused silica; diatomaceous earth; iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide; calcium carbonate, magnesium carbonate, zinc carbonate; Waxite clay, kaolin clay, calcined clay; carbon black; these fatty acid treated products, resin acid treated products, urethane compound treated products, fatty acid ester treated products, and the like.

Specific examples of the anti-aging agent include hindered phenol compounds.
Specific examples of the antioxidant include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).

  Specific examples of the pigment include inorganic pigments such as titanium oxide, zinc oxide, ultramarine, bengara, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, sulfate, etc .; azo pigment, phthalocyanine pigment, quinacridone Pigment, quinacridone quinone pigment, dioxazine pigment, anthrapyrimidine pigment, ansanthrone pigment, indanthrone pigment, flavanthrone pigment, perylene pigment, perinone pigment, diketopyrrolopyrrole pigment, quinonaphthalone pigment, anthraquinone pigment, thioindigo pigment, benzimidazolone Examples thereof include organic pigments such as pigments, isoindoline pigments, and carbon black.

  Specific examples of the plasticizer include diisononyl phthalate (DINP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate, methyl acetylricinoleate; tricresyl phosphate, trioctyl phosphate An adipate propylene glycol polyester, an adipate butylene glycol polyester, and the like.

  Specific examples of the thixotropic agent include aerosil (manufactured by Nippon Aerosil Co., Ltd.), disparon (manufactured by Enomoto Kasei Co., Ltd.), and the like.

Specific examples of the flame retardant include chloroalkyl phosphate, dimethyl / methyl phosphonate, bromine / phosphorus compound, ammonium polyphosphate, neopentyl bromide-polyether, brominated polyether, and the like.
Specific examples of the antistatic agent include quaternary ammonium salts; hydrophilic compounds such as polyglycols and ethylene oxide derivatives.

The tire puncture sealant of the present invention has a pH of less than 9.0. When the pH is within this range, the sealing performance equivalent to that of a conventional tire puncture sealing material can be obtained. Moreover, since content of ammonia etc. which causes an odor as pH is less than 9.0 is comparatively small, an irritating odor can be suppressed. The pH of the tire puncture sealing material of the present invention is preferably 8.5 or less, more preferably 5.5 to 8.5, because these properties are superior and rust is hardly generated on the steel cord of the tire.
In addition, the pH of the tire puncture sealant of the present invention is preferably 7.5 or more, more preferably 8.0 or more, from the viewpoint of excellent storage stability and the like, which can be stored in an automobile for a long period of time. preferable.

  The method for producing the tire puncture sealant of the present invention is not particularly limited. For example, the above chloroprene emulsion and antifreeze agent are added to a reaction vessel, and if necessary, a tackifier and various additives are mixed under reduced pressure. A method of sufficiently kneading using a stirrer such as a mixer may be mentioned.

In one preferred embodiment, the tire puncture sealant of the present invention has a hydrogen ion index reduced by an acid. For example, when a commercially available chloroprene-based emulsion is used, the commercially available chloroprene-based emulsion is often strongly alkaline, so that the resulting tire puncture sealant may have a pH of 9.0 or more. In such a case, an acid is added to lower the pH to the above pH range.
The timing of adding the acid is not particularly limited, and may be added in advance to a chloroprene emulsion, a tackifier, water, or the like, and the chloroprene emulsion and the antifreeze agent and the above optional components are being mixed or mixed. An acid may be added later.

  The acid is not particularly limited, and specific examples include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, phosphorous acid, acetic acid, propionic acid, formic acid, butyric acid, lactic acid, malic acid, and citric acid. Organic acids such as These may be used alone or in combination of two or more.

Hereinafter, the usage method of the tire puncture sealing material of this invention is demonstrated. However, the method of using the tire puncture seal material of the present invention is not limited to the following method.
First, the tire puncture seal material of the present invention is injected into the tire from the air filling portion of the tire. The method for injecting the tire puncture sealant of the present invention into the tire is not particularly limited, and a conventionally known method can be used, and examples thereof include a method using a syringe, a spray can and the like. The amount of the tire puncture sealant injected into the tire is not particularly limited, and is appropriately selected according to the size of the puncture hole.
Next, air is filled up to a predetermined air pressure.
Then, drive the car. Aggregates such as synthetic resin particles can be formed by compressive force or shear force received when the tire is in contact with the rotating ground, and the puncture hole can be sealed.

  The tire puncture seal material of the present invention has a sealing property equivalent to that of a conventional tire puncture seal material, has a relatively low viscosity, and has a low odor. Furthermore, when the pH of the tire puncture sealant is 7.5 or more, the tire puncture sealant is excellent in storage stability and can be stored in the automobile for a long time. Moreover, when pH is 5.5-8.5, it is hard to generate | occur | produce rust in the steel cord of a tire.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<Preparation of chloroprene emulsion (Formulation Examples 1 to 6)>
Chloroprene-based emulsion (C-84, manufactured by Sumika Bayer Urethane Co., Ltd.) and hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in the amounts (parts by mass) shown in Table 1 below. A chloroprene emulsion was obtained.
The hydrogen ion index of each obtained chloroprene emulsion was measured with a pH meter (manufactured by Hitachi High-Technology Corporation, the same applies hereinafter). The results are shown in Table 1.

<Preparation of NBR latex tire puncture sealant (Formulation Example 7)>
An NBR latex tire puncture sealant was prepared in accordance with the method of Example 1 described in JP-A-2005-170973.
Specifically, the following materials (1) to (5) were mixed using a stirrer to obtain an NBR latex tire puncture sealant (pH 9.5) of Formulation Example 7.

(1) Rubber latex: NBR latex (Nipol, manufactured by Nippon Zeon Co., Ltd.), 65% by mass in the puncture sealing agent
(2) Nylon fiber: content 2% by mass in the puncture sealant, fiber length 2 to 7 mm, fiber thickness 5 to 30 μm
(3) Antifreezing agent: 25% by mass in ethylene glycol and puncture sealing agent
(4) Thickener: Smectite clay, content in puncture sealing agent: 2% by mass
(5) Other: Water as the balance

<Examples 1-17 and Comparative Examples 1-3>
Each component shown in Table 2 below was mixed using a stirrer with the composition (parts by mass) shown in Table 2 to obtain each tire puncture sealant shown in Table 2.
The hydrogen ion index of each tire puncture sealant obtained was measured with a pH meter. Each tire puncture sealant was evaluated for rust prevention, odor, freezing point, sealability, thermal cycle stability, shaking test, storage stability, and liquid feeding property by the following methods.
The results are shown in Table 2.

(Rust prevention)
Each tire puncture sealant was applied to the surface of a steel sheet degreased with methyl ethyl ketone, allowed to dry at 20 ° C. for 24 hours, and then left in warm water at 50 ° C. for 7 days. Thereafter, the sealing material was peeled off from the steel sheet, and the surface of the steel sheet was visually observed to evaluate the presence or absence of rust.
The case where rust did not occur or the case where it occurred but was inconspicuous was indicated as “◯”, and the case where rust was conspicuous was indicated as “X”.

(Odor)
Each tire puncture sealant was checked for odor.
“O” indicates that there is no odor, “Δ” indicates that there is an odor but it is weak, and “X” indicates that the odor is strong.

(Freezing point)
The freezing point was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments).

(Sealability)
A hole was formed by penetrating a nail having a diameter of 5 mm through a tread of a member obtained by cutting the tire tread portion into a length of 15 cm and a width of 22 cm.
Assuming that the inside of the tire was injected in a 20 ° C., 65% RH environment, 50 g of each tire puncture sealant was hung from the back side (inside) of the tread to the hole portion.
In order to promote film formation, the periphery of the hole portion was hit with a mallet five times from the tread side.
After leaving for 20 minutes in an environment of 20 ° C. and 65% RH, water was sprayed from the tread side to the hole portion, and the presence or absence of water leakage to the back surface (inside) was observed.
The case where there was no water leak was indicated as “◯”, and the case where water leaked was indicated as “X”.

(Cool cycle stability)
Each tire puncture sealant was cooled at −20 ° C. for 8 hours and then heated at 80 ° C. for 16 hours. After repeating this cycle 10 times, the dispersion state was visually observed, and there was no precipitation and the particles were uniformly dispersed. “◯” was used for the sample, and “Δ” was used for the case where the aggregate or film was present.

(Shaking test)
In a 70 ° C. atmosphere, the glass bottle containing 200 g of the sealing material was sealed and shaken at 1 to 5 Hz for 60 hours.
Thereafter, the dispersion state was visually observed, and “◯” indicates that there was no precipitation / separation, and “Δ” indicates that there was an aggregate or film.

(Storage stability)
The obtained tire puncture sealant was put in a container, purged with nitrogen, sealed, and left at 80 ° C. for 100 days. Thereafter, the state of the tire puncture sealant was observed, the dispersion state was visually observed, and “◯” indicates that there was no precipitation / separation, and “Δ” indicates that there was an aggregate or film.

(Liquid feeding property)
A compressor having a power source (12 V) obtained from a cigar lighter was attached to a plastic container containing 500 ml of the obtained tire puncture sealant, and a nozzle was attached to a tire valve. Next, the sealing material was fed into the tire at 0.5 MPa pressure and normal temperature, and the time (seconds) required to feed all the sealing material in the plastic container into the tire was measured.

The components shown in Table 2 are as follows.
・ Natural rubber latex: HA, manufactured by Felfex, solid content 60% by mass, pH 11.5
-Tackifier: Harrier Star SK508, Harima Kasei Co., Ltd., solid content 54% by mass, pH 6.5
-Antifreeze agent (ethylene glycol): Wako Pure Chemical Industries, solid content 100% by mass

As is apparent from the results shown in Table 2 above, Comparative Example 1 having a high pH of 11.0 was excellent in stability, but rusted, had an irritating odor, and had low sealing properties. Moreover, the natural rubber latex tire puncture sealant (Comparative Example 2) had a high pH, rusted, an irritating odor, and low storage stability. Further, the NBR latex tire puncture sealant (Comparative Example 3) had high pH, rust was generated, there was an irritating odor, and the liquid feeding property was low.
On the other hand, Examples 1-17 had the sealing performance equivalent to Comparative Examples 2-3, and although Examples 1-3, 6-17 had some ammonia smell, the grade was weak. Moreover, Examples 1-6, 10, 14, and 17 were excellent in liquid feeding property. In Examples 1 to 17, there was little or no generation of rust. Furthermore, Examples 1-3 and 6-17 were excellent in storage stability.

Claims (8)

  A tire puncture sealant containing a chloroprene-based emulsion and an antifreezing agent and having a hydrogen ion index of less than 9.0.   The tire puncture sealant according to claim 1, which has a hydrogen ion index of 7.5 or more.   The tire puncture sealant according to claim 1 or 2, comprising 100 to 400 parts by mass of the antifreezing agent with respect to 100 parts by mass of the solid content of the chloroprene emulsion.   Furthermore, the tire puncture sealing material in any one of Claims 1-3 containing a tackifier.   The tire puncture sealant according to claim 4, wherein the tackifier is an emulsion obtained by emulsifying a resin.   The tire puncture sealing material according to claim 4 or 5, wherein the tackifier includes at least one selected from the group consisting of a rosin resin, a terpene resin, and a hydrogenated terpene resin.   The tire puncture sealing material according to any one of claims 4 to 6, wherein the solid content of the tackifier is 50 to 250 parts by mass with respect to 100 parts by mass of the solid content of the chloroprene emulsion.   The tire puncture sealing material according to any one of claims 1 to 7, wherein a hydrogen ion index is lowered by an acid.