JP4787502B2 - Puncture sealant - Google Patents

Description

  The present invention relates to a puncture sealant used when sealing a hole in 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 comprise colloidal dispersion polymers (latex) in an aqueous medium. Examples of the latex include polyethylene-butadiene latex, polyvinyl acetate latex, acrylic copolymer latex, nitrile latex, and polychloroprene latex.

However, the puncture sealants conventionally used as described above are not completely satisfactory. Since they are removed mechanically relatively quickly and the speed at which the puncture holes are blocked is slow, it takes a considerable amount of time for preliminary travel to complete the seal and allow travel. Moreover, since the lifetime is short, it is necessary to exchange frequently.
Japanese Patent No. 3210863

  In view of the above, an object of the present invention is to solve the above conventional problems. That is, an object of the present invention is to provide a puncture sealing agent having a high puncture hole sealing speed and long-term stability.

As a result of intensive studies to achieve the above object, the present inventors have found that the object can be achieved by the following present invention.
That is, the present invention is a puncture sealing agent for sealing a hole in a punctured tire, which contains a natural rubber latex and an antifreeze solution, and at least a part of the end of the natural rubber latex is modified with a carboxyl group or a hydroxyl group. Or one or more compounds selected from the group of acrylate compounds, epoxy compounds, styrene compounds, acrylonitrile compounds, and anhydrous maleic compounds are grafted onto at least some of the natural rubber latex It is a sealing agent characterized by being copolymerized .

Puncture sealant of the present invention, among the following first to the second aspect, that having a least one aspect.
(1) A 1st aspect is an aspect by which the terminal of at least one part of the said natural rubber latex is modified | denatured with the carboxyl group or the hydroxyl group.
(2) In the second embodiment, at least a part of the natural rubber latex is selected from the group consisting of an acrylate compound, an epoxy compound, a styrene compound, an acrylonitrile compound, and an anhydrous maleic compound. In this embodiment, the compound is graft copolymerized.
(3) The third aspect is an aspect further containing a low molecular weight natural rubber latex obtained by depolymerizing natural rubber latex.

  According to the present invention, it is possible to provide a puncture sealing agent having a high puncture hole sealing speed and long-term stability.

The puncture sealant of the present invention that seals a hole in a punctured tire contains natural rubber latex and antifreeze. At least a part of the natural rubber latex is modified or polymerized. By being modified or polymerized, the sealing speed of the puncture sealing agent can be increased, and long-term stability can be improved. Examples of the modification treatment include a treatment in which at least a part of the natural rubber latex is modified with a carboxyl group or a hydroxyl group . Upper Symbol treatment may be only one kind, or may be multiple combinations.

  As described above, from the viewpoint of further improving the stability, it is preferable that at least some of the ends of the natural rubber latex are modified with a carboxyl group or a hydroxyl group. A surfactant may be contained for the purpose of improving the stability of the puncture sealant. However, the surfactant contained in this way may be separated from the natural rubber latex when the temperature increases. On the other hand, by introducing a carboxyl group or a hydroxyl group directly into the end of the natural rubber latex, high stability can be ensured without being affected by other solvents. Also, good uniformity can be secured.

  In order to modify with a carboxy group, it is preferable to use at least one carboxylic acid such as acrylic acid, maleic acid, phthalic acid, succinic acid, and itaconic acid. In order to modify with a hydroxyl group, a phenol resin derivative is preferably used.

  The substitution rate with a carboxyl group or a hydroxyl group is preferably 0.5 to 95%, more preferably 10 to 50%. If it is less than 0.5%, a sufficient stabilizing effect due to terminal modification may not be obtained, and if it exceeds 95%, stability may be improved too much and sealing performance may be deteriorated. In order to control the substitution rate within the above range, the amount of monomer added and the addition of a reaction terminator may be performed.

  Further, at least a part of the natural rubber latex is graft copolymerized with one or more compounds selected from the group of acrylate compounds, epoxy compounds, styrene compounds, acrylonitrile compounds, and anhydrous maleic compounds. It is preferable. Stability can also be improved by graft copolymerization using these compounds as monomers.

  Examples of the compound that polymerizes with the double bond in the main chain of the natural rubber latex include the following compounds. That is, examples of the acrylate compound include acrylic acid, methacrylic acid and esters thereof. Specifically, (meth) acrylic acid lower alkyl esters such as methyl (meth) acrylate and ethyl (meth) acrylate. Other examples include glycidyl (meth) acrylate.

  Examples of the epoxy compound include 2-ethylhexyl glycidyl ether, lauryl glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, and glycerin diglycidyl ether.

  Examples of the styrenic compound include styrene, α-methylstyrene, vinyltoluene, and the like. Examples of acrylonitrile compounds include acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, α-chloroacrylonitrile and the like. Examples of maleic anhydride compounds include maleic acid, maleic anhydride, and derivatives thereof.

  The graft ratio is preferably 0.5 to 95%, and more preferably 10 to 40%. If it is less than 0.5%, the degree of improvement in adhesion (sealability) due to grafting may be reduced, and if it exceeds 95%, storage stability may be lowered. In order to control the graft ratio within the above range, the addition amount of the monomer and the addition of a reaction terminator may be performed.

  The molecular weight of the graft copolymer after grafting is preferably 5 to 60, more preferably 10 to 50, when the molecular weight of the natural rubber latex as the trunk polymer is 100. If it is less than 10, there is little improvement in sealing performance, and if it exceeds 60, stability may be lowered.

  The puncture sealing agent of the present invention preferably further contains a low molecular weight natural rubber latex obtained by depolymerizing natural rubber latex. By adding the low molecular weight natural rubber latex, the adhesion to the puncture hole can be improved. The content of the low molecular weight natural rubber latex in the puncture sealing agent is preferably 5 to 40% by mass.

  In consideration of the fact that the smaller the molecular weight, the higher the effect of improving the tackiness, and the like. 5 to 60%, preferably 10 to 50%. If it is less than 5%, the tackiness may be increased so that the injection into the tire may be difficult, and if it exceeds 50%, a sufficient tackiness improving effect may not be obtained. In order to control to the said range (5 to 60%), what is necessary is just to perform control of reaction time, selection of the kind of catalyst, and adjustment of the quantity.

  Further, the puncture sealing agent of the present invention contains an antifreeze liquid (an antifreezing agent). The antifreeze 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. The content of the preferred antifreeze agent is 10 to 40% by mass.

  The puncture sealing agent of the present invention as described above can contain various additives for the purpose of improving the other characteristics as long as the effect is not inhibited. Hereinafter, the additive will be described.

(Resin adhesive)
As the resin-based adhesive, a terpene resin such as a terpene phenol resin can be used. As the terpene phenol resin, α-pinene phenol resin, dipentene phenol resin, terpene bisphenol resin, or hydrogenated one of these can be used. Commercially available products can also be used. In addition, when the puncture sealing agent of this invention contains a low molecular weight natural rubber latex, the said resin adhesive is not necessarily required.

  The content of the resin adhesive is preferably in the range of 3 to 30% by mass, more preferably in the range of 5 to 25% by mass, and further preferably in the range of 7 to 20% by mass. By setting it in the range of 3 to 30% by mass, practical and good sealing properties can be exhibited. The resin-based adhesive is preferably added in the state of an aqueous dispersion of the rubber latex or an aqueous emulsion of the rubber latex in consideration of improving the sealing property.

(Short fiber)
The short fibers enter a hole (defect portion) generated in the tire due to puncture to cause clogging, and serve to close the hole quickly and reliably. The content of short fibers in the puncture sealing agent is preferably 0.1% by mass to 5% by mass.

  If it is less than 0.1% by mass, the sealing performance due to the addition of the short fibers may not be sufficiently exhibited. On the other hand, if it exceeds 5% by mass, the short fibers will be entangled, the viscosity will increase and the ease of injection will be lowered, and it will be difficult to fully perform the above-mentioned role, so the sealing performance will also be reduced. May end up. The short fiber content is preferably 0.3 to 4% by mass, and more preferably 0.5 to 3% by mass.

  In addition, it is preferable to design various types of short fibers in order to sufficiently fulfill the role as described above. Therefore, the specific gravity (S), length (L), diameter (D), and ratio of length to diameter (L / D) of the short fibers are preferably set in the following ranges, respectively.

(1) Specific gravity (S): 0.8 ≦ S ≦ 1.4 (more preferably 0.9 ≦ S ≦ 1.3, and still more preferably 1.0 ≦ S ≦ 1.2).
If the specific gravity is less than 0.8, the short fibers may float upward and the long-term separation stability may be low. If the specific gravity exceeds 1.4, the short fibers may sink and the long-term separation stability may be lowered. May be low.

(2) Length (L): 0.05 ≦ L ≦ 10 mm (more preferably 0.08 ≦ L ≦ 8 mm, still more preferably 0.1 ≦ L ≦ 6 mm).
If the length is less than 0.05 mm, the short fiber may not fully exhibit the effect of causing clogging in the defective portion due to puncture and improving the sealing property. Therefore, the sealing performance may be reduced.

(3) Diameter (D): 1 ≦ D ≦ 100 μm (more preferably 3 ≦ D ≦ 80 μm, still more preferably 5 ≦ D ≦ 50 μm).
If the diameter (thickness) is less than 1 μm, the role of short fibers that cause clogging and improve the sealing performance may not be sufficiently exhibited. If the diameter (thickness) exceeds 100 μm, the relative number of short fibers may not be achieved. May decrease the sealing performance.

(4) Ratio of length to diameter (L / D): 5 ≦ L / D ≦ 2000 (more preferably 20 ≦ L / D ≦ 1600, more preferably 50 ≦ L / D ≦ 1200, particularly preferably 100 ≦ L / D ≦ 300).
If L / D is less than 5, the role of short fibers that cause clogging and improve sealability may not be sufficiently exhibited. If L / D exceeds 2000, lumps of short fibers may occur. , May cause deterioration of sealability and ease of injection.
In addition, short fibers made of one material can be used in a certain shape, but short fibers made of a plurality of materials can be used in various shapes within the range described above.

  The short fiber is not particularly limited in its material, but is preferably composed of polyester, polyethylene, nylon, polypropylene, or a composite of two or more thereof, polyethylene, nylon, polypropylene, and a composite of two or more of these. It is more preferable that it consists of either. By using such short fibers, better separation stability can be obtained.

  It is preferable that the short fiber is treated with a solvent such as a higher alcohol derivative and / or a betaine activator in the whole amount or a part thereof (preferably the whole amount). By this treatment, the solvent acts as an active agent, and the dispersibility of the short fibers can be improved. The treatment may be performed before or after inclusion in the puncture sealant. The treatment can be carried out by impregnating the short fiber with the solvent or spraying the solvent. As the higher alcohol derivative, polyglycol polyester is suitable.

  The addition amount of the solvent (amount absorbed by the short fiber by the above treatment) is preferably 0.2 to 20% by mass, more preferably 0.5 to 10% by mass of the short fiber mass, More preferably, it is 1 to 6%. If the amount added is too small, the effect of dispersing the short fibers may not be obtained and the treatment may be insufficient. If the amount is too large, further improvement in the effect cannot be expected.

  In the puncture sealing agent as described above, the content of the solid component (hereinafter sometimes referred to as “solid content”) in the puncture sealing agent is preferably 5 to 70% by mass.

  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).

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

Further, the viscosity of the puncture sealant is preferably 3 to 6000 mPa · s under the conditions assumed as actual use conditions (at least in a range of 60 ° C. to −30 ° C. before filling into the tire) It is more preferably 5 to 4500 mPa · s, further preferably 8 to 3000 mPa · s, particularly preferably 10 to 3000 mPa · s, and most preferably 15 to 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 puncture sealant of the present invention can contain water for dilution. Further, a normal dispersant, an emulsifier, a foam stabilizer, and a pH adjuster such as caustic soda may be added to the puncture sealant.

  In addition, one or more fillers may be mixed in the puncture sealant so that it can be quickly sealed and reliably sealed even in large holes. Examples of the stable filler include silicic acid, chalk, carbon black, synthetic resin reinforced with glass fiber, polystyrene particles, powder rubber obtained by grinding vulcanized products such as tires, sawdust, moslaver particles, foam particles for cut flowers Etc. can be adopted. Among these, particularly preferred fillers are rubber powder bonded with silicic acid, and synthetic resin reinforced with glass fiber.

  The filler can be added directly to the puncture sealant. However, as long as the filler has a size that makes it difficult or impossible to guide the puncture sealant through the valve without changing the valve size, these fillers generally rim the tire. Sometimes it is introduced into the inside of the tire, and when a puncture occurs in the tire, a puncture sealing agent is injected to achieve sealing.

  The filler is preferably added to the puncture sealant at about 20 to 200 g / liter, more preferably 60 to 100 g / liter, or disposed inside the tire in the tire rim set. On the other hand, a dispersant or emulsifier for a resin adhesive, preferably water, may be added as a liquid component, and a liquid resin adhesive may be used if necessary.

  The puncture sealant can be produced by mixing the above-described materials by a known method. The production, storage, and filling of the puncture sealing agent is preferably performed in an atmosphere of nitrogen or a rare gas in order to avoid oxidation and the like.

  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.

  Such a puncture sealant itself can be introduced into the inside of a tire by using various pump-up devices, for example, a spray can containing a propane / butane mixed gas as a fuel gas, and is shown in FIG. The pump-up device 20 can be used more preferably.

  In the pump-up device 20 shown in FIG. 1, a small air compressor 1 is used as the pressure source. This air compressor 1 is connected to a gas introduction part 3 of a pressure vessel 4 via a hose 2. The gas introduction part 3 is formed as a riser tube that can be closed by a stopper valve 5 and extends to the liquid level of the puncture sealing agent 6 accommodated in the pressure resistant container 4.

  The pressure vessel 4 has an outlet valve 7 for taking out the puncture sealing agent 6. One end of a hose 8 is connected to the outlet valve 7, and the other end of the hose 8 is connected to a tire valve 10. A screw adapter 9 to be screwed is attached.

  The pressure vessel 4 has a filling stub 12 and a jacket 11 filled with water. The filling stub 12 can be filled with calcium chloride as a heating source as required. When the puncture sealant 6 is frozen at a low temperature, the puncture sealant 6 is heated to an available temperature by the heat released by the hydration action of the heating source.

  An electric cable 13 is connected to the air compressor 1, and its plug 14 is inserted into a cigarette lighter, for example.

  When puncture occurs in the tire, the screw adapter 9 is screwed to the tire valve 10, the air compressor 1 is connected to the cigarette lighter, and the plug valve 5 is opened in the gas introduction part 3 of the pressure vessel 4. The compressed air introduced from the air compressor 1 into the pressure vessel 4 through the gas introduction part 3 pushes out the puncture sealing agent 6 from the outlet valve 7 and introduces the tire valve 10 into the inside of the tire. Thereafter, air is refilled into the tire, causing the tire to inflate at a specific internal pressure. When this is finished, the screw adapter 9 is removed from the tire valve 10 and the air compressor 1 is stopped. Immediately after this, after preliminarily traveling for a certain distance and sealing the puncture hole while spraying the puncture sealing agent 6 inside the tire, the pump-up device 20 is connected again and the tire is pumped again to the required internal pressure. Up.

  Further, the puncture sealing agent of the present invention can be more preferably used by the pump-up device 30 shown in FIGS. 2A and 2B. In the pump-up device shown in FIGS. 2A and 2B, parts common to the pump-up device 20 shown in FIG.

  The pump-up device 30 includes a resin bottle 22 that is a container for the puncture sealing agent 6 shown in FIG. 2A, and an air compressor 1 as a pressure source shown in FIG. 2B. The bottle 22 contains the puncture sealing agent 6 necessary for one puncture repair. A hose 24 having an adapter 26 disposed at the tip is connected to the bottle 22. An adapter 9 is also arranged at the tip of the hose 2 connected to the air compressor 1. However, if the hose 24 of the bottle 22 can be directly connected to the tire valve 26, the adapter 9 may be omitted.

  When the puncture occurs, the adapter 26 of the bottle 22 is screwed to the tire valve 10. Thereby, it communicates in the tire through the hose 24 and the adapter 26. In this state, as shown by a two-dot chain line (imaginary line) in FIG. 2A, the operator squeezes the bottle 22 and squeezes the puncture sealing agent 6 out of the bottle 22, thereby passing the puncture sealing agent through the hose 24. 6 is injected into the tire.

  When the injection of the puncture sealing agent 6 from the bottle 22 into the tire is completed, the operator removes the adapter 22 from the tire valve 10 and separates the bottle 22 from the tire.

  Next, the operator screws the adapter 9 of the air compressor 1 to the tire valve 10 and causes the air compressor 1 to communicate with the tire through the adapter 9 and the hose 2. In this state, the operator operates the air compressor 1 to refill the tire with pressurized air, and inflates the tire with a specific internal pressure. When this is finished, the operator removes the adapter 9 from the tire valve 10 and stops the air compressor 1. Immediately after this, after traveling for a predetermined distance and sealing the puncture hole while spraying the puncture sealant 6 inside the tire, the operator reconnects the air compressor 1 of the pump-up device 30 and removes the tire. Pump up again to the required internal pressure.

  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.

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

[Example 1]
A puncture sealant was produced by adding 30% by mass of propylene glycol to a latex having a solid content of 70% by mass obtained by graft copolymerization of styrene and deproteinized natural rubber latex.

[Example 2]
A puncture sealant was produced by adding 30% by mass of propylene glycol to a latex having a solid content of 70% by mass obtained by graft copolymerization of acrylic acid with deproteinized natural rubber latex.

[ Reference Example 3]
By depolymerizing the deproteinized natural rubber latex, the molecular weight was reduced to 1/10 of the original latex to produce a low molecular weight natural rubber latex having a solid content of 70% by mass.

  A puncture sealing agent was produced by mixing 40 parts by mass of the low molecular weight natural rubber latex with 100 parts by mass of deproteinized natural rubber latex that was not depolymerized, and further mixing 40 parts by mass of propylene glycol.

[Comparative Example 1]
A puncture sealing agent was produced in the same manner as in Example 1 except that graft polymerization with styrene was not performed.

[Evaluation]
(Evaluation of puncture hole sealability)
A hole of φ2.3 mm was drilled in a tire tread groove portion of one tire, and the produced puncture sealing agent (each of Examples 1 to 4 and Comparative Example 1) was injected and mounted on a car. Thereafter, 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 the distance until the hole was completely sealed was measured. The results are shown in Table 1 below.

(Evaluation of stability)
Example 1-2, each of the puncture sealing agent prepared in Reference Example 3 and Comparative Example 1 in the same amount taken and kept at 80 ° C., and observed time gelation occurs (in days) visually. The results are shown in Table 1 below.

From the results of Table 1, in Examples 1 and 2 , since at least a part of the natural rubber latex was modified or polymerized, the hole sealing speed was high. Moreover, it has confirmed that it had favorable long-term stability. From these results, it was found that the puncture sealing agent of the present invention was practically excellent.

It is the schematic which shows an example of the sealing and pump-up apparatus used in order to fill a tire with the puncture sealing agent which concerns on embodiment of this invention. It is the schematic which shows the other example of the sealing pump-up apparatus used in order to fill a tire with the puncture sealing agent which concerns on embodiment of this invention.

Explanation of symbols

3 Gas introduction part 4 Pressure vessel 6 Sealing agent 7 Outlet valve 20 Pump-up device 30 Pump-up device

Claims (2)

A puncture sealant that seals punctured tire holes,
Contains natural rubber latex and antifreeze,
At least a part of the natural rubber latex is modified with a carboxyl group or a hydroxyl group, or at least a part of the natural rubber latex is an acrylate compound, an epoxy compound, a styrene compound, an acrylonitrile compound, And a puncture sealant characterized in that one or more compounds selected from the group of anhydrous maleic compounds are graft copolymerized. The puncture sealant according to claim 1, wherein styrene or acrylic acid is graft copolymerized with at least a part of the natural rubber latex.