JP2007145923A - Tire tube filling elastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire tube filling elastic resin composition having fluidity high enough to be poured through a valve when molten and developing adhesion to a tire tube when cured by gelation and to thereby produce easily within a short time a tire not suffering from puncture and providing good drive quality for a long time. <P>SOLUTION: An elastic resin composition containing 10 to 20 wt.% thermoplastic styrene elastomer, 5 to 15 wt.% tackifier, and 65 to 85 wt.% process oil and having a melt viscosity of 10 cP to 300 P at a melt temperature of 160°C is used as a tire tube filling elastic resin composition which is poured into a tire tube through its air injection valve. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an elastic resin composition that is used by being filled in a tire tube of a tire such as a bicycle, a wheelchair, a motorcycle, an electric bicycle, an agricultural vehicle, or a forklift.

  Conventional pneumatic tires have a problem of puncture due to natural outflow of air from the valve portion or stepping out of a nail or the like. As means for solving this problem, various techniques for eliminating the occurrence of puncture by injecting resin into the tire tube have been proposed. For example, Patent Document 1 discloses a technique for injecting a polyurethane foam resin from an air injection valve. In this technology, a main agent composed of polyol and polyisocyanate and a secondary agent composed of a foaming agent, a catalyst, and the like are mixed using a high-pressure foaming machine, pressed into a tire tube through a valve, and then foamed and cured at room temperature. A solid tire for a bicycle is manufactured by filling a resin into a tube. However, this technique requires a special injection machine combined with a two-component mixing machine called a high-pressure foaming machine, and cannot be easily constructed in a wide range of work sites including bicycle retail repair shops. In addition, tires using this resin not only have poor cushioning and riding comfort, but are also inferior in durability, and have the problem of causing “sagging” in the tire in about one year. That is, when the bicycle is ridden, the tire is compressed and deformed, so that the resin gradually deteriorates and is not easily restored to the original state, and the elasticity decreases with the passage of time. For this reason, there arises an inconvenience that vibration is increased and it is heavy to ride a bicycle. As described above, there is a problem that good riding comfort cannot be maintained over a long period of time.

Patent Document 2 discloses a “tire puncture-resistant soft resin material that can be injected into a tire tube”, and the resin material is a mixture of 5% or more of paraffin oil in a polystyrene-based or polyolefin-based thermoplastic elastomer. It is. However, since this resin material is not sticky, the adhesion between the tire tube and the resin material is low. For this reason, after filling and curing (gelation) of the resin material, if the amount of resin injected and filled is insufficient, or if air is entrained during the injection, as described later, as the tire travels, the resin The bubbles in the inside expand to exist at the interface between the tire tube and the resin as a large air pocket. In other words, the tire tube and the resin are separated and a non-uniform portion of the resin is formed in the tire, and the tire is compressed and deformed during rotation, generating excessive shock and vibration, and the ride comfort is lowered with time. There was a problem that.
Japanese Unexamined Patent Publication No. 08-142603 JP 2005-126654 A

  The present invention provides an elastic resin composition for filling a tire tube (hereinafter simply abbreviated as “elastic resin composition”) that has fluidity that can be injected from a valve at the time of melting and adhesion to the tire tube after gel curing. However, an object of the present invention is to easily and quickly manufacture a tire that does not generate puncture and can maintain good riding comfort for a long period of time.

  The invention of claim 1 for solving the above-mentioned problems is an elastic resin composition for filling a tire tube, which is injected and filled into a tire tube via a tire air injection valve, and comprises a styrenic thermoplastic elastomer. It is characterized by containing 10 to 20% by weight, 5 to 15% by weight of a tackifier and 65 to 85% by weight of process oil, and having a melt viscosity of 10 cP to 300 P at a melting temperature of 160 ° C.

  The elastic resin composition for filling a tire tube of the invention of claim 1 is injected into the tire tube from a valve by a pressure injection means such as a pump to fill the tire tube. At this time, when the elastic resin composition has a mixing ratio of materials such that the melt viscosity of the resin composition is 10 cP to 300 P, the elastic resin composition can easily flow even from the inside of the valve having a small diameter and can be injected into the tube. Has fluidity (viscosity). Therefore, the elastic resin composition can be easily injected and filled into the tire tube without any trouble.

  Further, the elastic resin composition that has been gelated after filling has an adhesive force corresponding to a predetermined vertical peeling force and is in close contact with the tire tube by the action of the tackifier. For this reason, riding comfort is improved by increasing the sense of unity between the gelled donut-shaped elastic resin composition and the tire tube. Further, even when a void is generated due to air mixing at the time of injecting the elastic resin composition or insufficient injection resin, the gelled elastic resin composition is not peeled off from the tire tube. For this reason, air does not easily collect at the interface between the inner peripheral surface of the tire tube and the gelled resin even when the tire is running, or even if it accumulates, the air does not collect and form a large air reservoir. And good ride comfort is maintained.

The invention of claim 2 is characterized in that, in the invention of claim 1, the perpendicular peeling force at normal temperature of the gelled elastic resin composition is 0.1 to 0.5 N / cm ² .

According to the invention of claim 2, in addition to the effects of the invention of claim 1, the perpendicular peeling force at normal temperature of the gelled elastic resin composition is 0.1 to 0.5 N / cm ^2. It is good as a tire because it can hold both the elasticity (impact absorbability) force of the gelled elastic resin composition and the necessary adhesion (adhesion) force to the tire tube when the mixing ratio of the tackifier is Secure ride comfort.

  According to the present invention, by adding a tackifier to the thermoplastic elastomer and the process oil, at the time of melting, it has fluidity that can be injected and filled into a tire tube via a valve, and it is cooled and gelled (cured). Thereafter, an elastic resin composition having not only an elastic force but also an adhesive force to the tube is obtained. Therefore, by using the elastic resin composition according to the present invention as a filler for a tire tube, in addition to excellent shock absorption, a tire that does not greatly reduce the riding comfort even when some air is caught in the tire tube Can be manufactured easily and in a short time.

  The present invention is an elastic resin composition for filling a tire tube in which a tackifier is added to a thermoplastic elastomer and process oil. Hereinafter, the present invention will be described in more detail with reference to examples.

  First, the raw material of the present invention will be described. The thermoplastic elastomer of the present invention is a styrenic thermoplastic elastomer, which is a block copolymer comprising a polystyrene block and an elastomer block having a polyolefin structure. Specific examples of the styrenic thermoplastic elastomer in the embodiment of the present invention include polystyrene-poly (ethylene / propylene) block (SEP) and polystyrene-poly (ethylene / propylene) block-polystyrene (SEEPS). In addition to the styrene thermoplastic elastomers described above, SBS (styrene-butadiene-styrene copolymer), SEBS (styrene-ethylene-butadiene-styrene copolymer), SEBC (styrene-ethylene-butadiene-high crystalline ethylene copolymer). Polymer), SEPS (styrene-ethylene-propylene-styrene copolymer) and the like can be used similarly.

  The process oil of the present invention comprises mineral oils such as naphthenic oil and paraffinic oil. This is used as a plasticizer or softener for the thermoplastic elastomer. Even if any of naphthenic oil, paraffinic oil, or a mixture thereof is used, the effect as a process oil is the same, but in the examples of the present invention, naphthenic oil is used.

  The tackifier of this invention is resin added in order to give adhesive force to the gelatinized elastic resin composition. Examples include terpene resins, α-pinene resins, β-pinene resins, aromatic modified terpene resins, hydrogenated terpene resins, rosin ester resins, hydrogenated rosin resins, and aliphatic saturated hydrocarbon resins. Although any of the above resins can be expected to have the same effect, an aromatic modified terpene resin and a hydrogenated terpene resin are used in the examples of the present invention.

  The mixing ratio of each raw material is the viscosity (fluidity) of the elastic resin composition in the molten state, the elasticity (impact absorbability) of the gelled elastic resin composition, and the shape retention that can maintain the original shape immediately after gelation for a long period of time. Is adjusted to the optimum condition. Here, when an elastic resin composition is prepared by a method similar to the present invention with the mixing ratio of the thermoplastic elastomer as the raw material being less than 10% by weight or the mixing ratio of the process oil being more than 85% by weight, The concentration of the elastomer in the process oil is reduced, and the elastic resin composition obtained by gelation is very soft. The ride feels as if you are riding a tire that is out of air, you can not get a moderate rebound (elastic) force from the ground, and run as if the tire sticks to the ground and ride lightly Absent. On the other hand, when an elastic resin composition is prepared with a mixing ratio of the thermoplastic elastomer exceeding 20% by weight or a mixing ratio of the process oil being less than 65% by weight, the concentration of the thermoplastic elastomer with respect to the process oil increases and gelation occurs. The finished elastic resin composition is very hard, and the repulsion (elasticity) force from the ground is too large, and even small unevenness on the ground will cause a large impact and vibration and will sound on the body, so riding comfort is poor. In addition, the melt viscosity at 160 ° C. exceeds 300 P, and injection from a valve having a small diameter becomes difficult (details on the melt viscosity at 160 ° C. will be described later). For the above reasons, it is optimal to mix the mixing ratio according to the present invention, that is, 10 to 20% by weight of the thermoplastic elastomer and 65 to 85% by weight of the process oil.

  Next, a method for injecting the elastic resin composition into the tire tube will be described with reference to FIG. In FIG. 1, a solution-like elastic resin composition RS (hereinafter abbreviated as “solution-like resin RS”) is injected into a rear wheel WR of an existing bicycle B using a resin injection device including a pump 1. It is the whole state schematic. Using this resin injecting device, a solution resin is produced by the pressure of the pump 1 through a valve V inside a tire tube (not shown) inscribed in the tire forming the front wheel WF and the rear wheel WR of the existing bicycle B. After injecting and filling RS, this is gelled while naturally cooling to produce a solid tire. First, the thermoplastic resin, process oil, and tackifier, which are raw materials, are heated by the heater 7 and dissolved, and the solution resin RS is stored in the solution resin container 2 while maintaining airtightness. ing. A resin injection tube 3 is inserted into the bottom of the side wall of the solution resin container 2, and the pump 1 is incorporated in the resin injection tube 3 near the outlet of the solution resin container 2. When the solution resin RS in the solution resin container 2 is sucked by the pump 1 and discharged toward the tire tube, the solution resin RS passes through the resin injection tube 3, the connecting tube 4, and the valve V, and the rear wheel WR. Flows into the tire tube. After injection and filling, it is naturally cooled and gelled. In addition, 5 of FIG. 1 points out the valve | bulb integrated in the resin injection pipe 3, and prevents the backflow of solution-like resin RS immediately after injection | pouring filling. In addition, in order to let the air originally in the tire tube escape to the outside, the tire and the tire tube at the upper part of the rear wheel WR are made to penetrate a small amount in advance with the hollow needle 6 before the solution-like resin RS is injected.

  Since the high temperature solution resin RS is injected into the tire tube through the valve V having a small diameter by the above injection method, the following two points are considered as conditions required for the solution resin RS at the time of injection. There must be. The first point is that the temperature at which the solution-like resin RS is injected is such that the tire, the tire tube, and the adhesive used for the bonding are not thermally deteriorated, such as a synthetic rubber. The point is that the viscosity (viscosity) of the solution-like resin RS in that state must pass through a valve having a small diameter (about 1 to 3 mm) without being stagnated and be press-fitted into the tube.

  Here, in order to prevent an adverse effect due to thermal deterioration of the tire, the tire tube, and the adhesive, the upper limit of the temperature at which the solution-like resin RS is injected is considered to be about 200 ° C.

  As for the viscosity, if the value is 100 P or less, even a valve having a minimum diameter of about 1 mm can easily flow, and the efficiency of the press-fitting work of the solution-like resin RS into the tube is increased. In addition, it is presumed that there is almost no solution state in which the viscosity of the solution-like resin RS is 10 cP or less. On the other hand, when it exceeds 300 P, fluidity is lowered and injection from the valve becomes difficult.

  In the present invention, the elastic resin composition has a melt viscosity at 160 ° C. of 10 cP to 300 P. That is, in order to satisfy both of the above two conditions, the resin resin RS produced by heating the raw material in the solution resin container 2 is kept at 160 ° C. using the resin injection device, and the tire is connected via the valve V. It is only necessary to press-fit and fill the tube, and this operation can be carried out easily and in a short time.

  Next, the relationship between the adhesive strength of the elastic resin composition RS ′ after cooling gelation on the inner peripheral surface of the tire tube and the riding comfort will be described with reference to FIGS. FIG. 2 is a partial cross-sectional view along the circumferential direction of the tire showing the change of the bubbles 13 mixed in the tire tube 12 at the time of filling with the solution-like elastic resin composition RS that does not have an adhesive force after gelation. is there. First, when the solution-like elastic resin composition RS is insufficiently filled into the tire tube 12 or when air is mixed during the injection of the solution-like elastic resin composition RS, the elastic resin composition after cooling gelation A space (bubble 13) is formed in the object RS ′ [FIG. 2 (A)]. When traveling with this tire, a crack 16 is gradually formed between the inner peripheral surface of the tube 12 and the bubble 13 under pressure from the ground [FIG. 2 (b)]. When the crack 16 occurs, the elastic resin composition RS ′ wets the inner peripheral surface of the tire tube 12 due to its cohesive force, but lacks adhesive force, so that the generated crack 16 gradually expands, and the bubbles 13 are expanded in the tube 12. It can be made at the interface between the peripheral surface and the elastic resin composition RS ′ [FIG. 2 (C)]. The bubbles 13 formed at the interface between the inner peripheral surface of the tube 12 and the elastic resin composition RS ′ are enlarged by collecting the peripheral bubbles 13 in the course of continuing the running of the tire, and become elastic with the inner peripheral surface of the tube 12 as a large air reservoir 17. It comes to exist in the interface of resin composition RS '[Drawing 2 (d)]. When the large air reservoir 17 is generated, the large air reservoir 17 is greatly compressed and deformed as compared with the small air bubbles 13 dispersed in the elastic resin composition RS ′ during running (rotation) of the tire. For this reason, every time the tire rotates while traveling, it receives shock and vibration that are “slammed”, and the ride comfort deteriorates. In addition, since it is thought that the air reservoir 17 is in the direction of reducing the surface energy by reducing the surface area, the reverse change from the large air reservoir 17 to the plurality of small bubbles 13 is followed. It is hard to think. Further, it is considered that the interface energy between the inner peripheral surface of the tire tube 12 and the air reservoir 17 is negligible, and the interface between the air reservoir 17 and the elastic resin composition RS ′ is obtained when the air reservoir 17 is in contact with the inner peripheral surface of the tire tube 12. Since the change proceeds in the direction of reducing energy, the large air reservoir 17 at the interface between the inner peripheral surface of the tire tube 12 and the elastic resin composition RS ′ is less likely to return to the elastic resin composition RS ′. In addition, 11 and 15 of FIG. 2 show the tire skin and rim of a wheel, respectively.

  FIG. 3 is a partial cross-sectional view along the circumferential direction of the tire showing the change of the bubbles 13 mixed in the tire tube 12 when the elastic elastic resin composition RS having adhesive strength after gelation is filled. Similarly to the above, when the tire-tube is not sufficiently filled with the solution-like elastic resin composition RS or when air is mixed during the injection of the solution-like elastic resin composition RS, the elastic resin composition RS after cooling gelation A space (bubble 13) is created inside [Fig. 3 (A)]. When running with this tire, the elastic resin composition RS ′ has adhesive strength, so that the elastic resin composition RS ′ is in close contact with the inner peripheral surface of the tire tube 12 and cracks 16 between them even when subjected to pressure from the ground. Is unlikely to occur [Fig. 3 (b)]. Further, even when the crack 16 occurs, the adhesion between the tire tube 12 and the elastic resin composition RS ′ is high, so that the crack 16 does not expand, and there is a bubble at the interface between the tire tube 12 and the elastic resin composition RS ′. 13 is rarely accumulated [Fig. 3 (b ')]. Furthermore, even if the bubbles 13 are accumulated at the interface, the elastic resin composition RS ′ is applied to the inner peripheral surface of the tire tube 12 rather than the force of the bubbles 13 accumulated for stabilization of energy. By exceeding the adhesive force, it does not grow to a large air pocket, and remains as an air bubble 13 at the interface between the inner peripheral surface of the tire tube 12 and the elastic resin composition RS ′. Therefore, even if the running time elapses, although the small bubbles 13 are scattered in the tire tube 12, uneven portions of the elastic resin composition RS ′ that undergoes large compression deformation such as air pockets are provided. Since it does not occur, the impact and vibration during running of the tire are small, and good riding comfort is maintained over a long period of time.

  In the present invention, in order to increase the adhesion between the tire tube and the elastic resin composition, the gelled elastic resin composition is given adhesive force, and in addition to the thermoplastic elastomer and the process oil which are the raw materials of the elastic resin composition. Then, a resin as a tackifier was blended. Since the tackifier generally provides high adhesive strength and cohesive strength at a low concentration, the blending amount of the tackifier is adjusted so as to exhibit sufficient adhesive strength to maintain good riding comfort of the tire.

  In the present invention, the vertical peeling force is adopted as an index of the adhesive strength of the gelled elastic resin composition. Although the evaluation method of the vertical peeling force will be described later, the gelled elastic resin composition is lightly pressed against the resin bonding wall standing perpendicular to the horizontal plane, and is pulled in the horizontal direction to be peeled off from the resin bonding wall. By measuring the tensile force when peeled and converting this per unit area, the adhesive force of the elastic resin composition to the resin adhesive wall can be evaluated, which is an index of the adhesive force of the elastic resin composition to the tire tube .

When the perpendicular peeling force of the gelled elastic resin composition is less than 0.1 N / cm ² , the adhesive force of the elastic resin composition to the resin bonding wall is small. That is, the adhesion between the tire tube inner peripheral surface and the elastic resin composition is low, and a sufficient effect for maintaining good riding comfort cannot be expected. Further, when the vertical peeling force exceeds 0.5 N / cm ² , the amount of tackifier added is too much for the thermoplastic elastomer, so the gelled elastic resin composition is hard and loses elasticity. Riding comfort is worse.

In the present invention, by adding 5 to 15% by weight of the tackifier, the vertical peeling force after cooling and gelation of the elastic resin composition exhibits 0.1 to 0.5 N / cm ² , and the tire tube and the elastic resin The adhesion of the composition can be ensured. Therefore, the gelled elastic resin composition has not only its own elasticity (shock absorption) but also adhesion to the tube, and a tire filled with this has good riding comfort as a tire. Obtainable.

  In the elastic resin composition, the case where the tackifier was blended and the case where it was not blended were evaluated. As an example and a comparative example, each evaluation result is shown in FIG.

[Example 1]
As a thermoplastic elastomer, Kuraray's brand name “Septon 1000 Series” oil-free polystyrene-poly (ethylene / propylene) block (SEP) 14% by weight, as a process oil, Nippon Sun Oil Co., Ltd. 150% naphthenic oil of 150 ”, and 10% by weight of hydrogenated terpene resin of Yasuhara Chemical Co., Ltd. trade name“ Clearon P125 ”as a tackifier as a raw material, and melt-mixed at 200 ° C. to obtain an elastic resin composition Created. This elastic resin composition had a viscosity of about 100 P at 160 ° C., and the vertical peeling force after cooling gelation was about 0.3 N / cm ² . Moreover, the bicycle provided with the tire which injected this elastic resin composition at 160 degreeC using the said resin injection | pouring apparatus was able to ride comfortably without abnormality after half a year.

[Example 2]
As a thermoplastic elastomer, Kuraray's brand name "Septon 4000 series" oil-free polystyrene-poly (ethylene-ethylene / propylene) block-polystyrene (SEEPS) 12% by weight, as process oil, Nippon Sun Oil Co., Ltd. 80% by weight of naphthenic oil with the trade name “Supreme 150” and 8% by weight of aromatic modified terpene resin with the trade name “YS Resin TO125” of Yasuhara Chemical Co., Ltd. as a tackifier are melt mixed at 200 ° C. Thus, an elastic resin composition was prepared. This elastic resin composition had a viscosity of about 100 P at 160 ° C., and the vertical peeling force after cooling gelation was about 0.2 N / cm ² . Moreover, the bicycle provided with the tire which injected this elastic resin composition at 160 degreeC using the said resin injection | pouring apparatus was able to ride comfortably without abnormality after half a year.

[Comparative Example 1]
As a thermoplastic elastomer, Kuraray's product name “Septon 1000 Series” oil-free polystyrene-poly (ethylene / propylene) block (SEP) 14% by weight, as process oil, Idemitsu Kosan Co., Ltd. product name “Diana Process” Resin was prepared by melting and mixing at 200 ° C. using 86% by weight of paraffin oil of “Oil PW-32” as a raw material. This resin had a viscosity of about 300 P at 180 ° C., and the vertical peeling force after cooling gelation was almost zero. In addition, a bicycle equipped with a tire in which this resin was injected at 180 ° C. using the above resin injection device had a soft spot on a part of the rear wheel after six months, and a decrease in riding comfort was recognized. There was a thing.

[Comparative Example 2]
As a thermoplastic elastomer, Kuraray's product name “Septon 4000 Series” oil-free polystyrene-poly (ethylene-ethylene / propylene) block-polystyrene (SEEPS) 13% by weight, as process oil, a product of Idemitsu Kosan Co., Ltd. A resin was prepared by melting and mixing at 200 ° C. using 87% by weight of paraffin oil having the name “Diana Process Oil PW-32” as a raw material. This resin had a viscosity of about 20 P at 160 ° C., and the vertical peeling force after cooling gelation was almost zero. In addition, a bicycle equipped with a tire in which this resin was injected at 160 ° C. using the above resin injection device had a soft spot on a part of the rear wheel after six months, and a decrease in ride comfort was recognized. There was a thing.

A method for evaluating the vertical peeling force will be described with reference to FIG. First, the digital push-pull gauge 23 includes a gauge body 23a and a spring portion 23b. The digital push-pull gauge 23 smoothly moves in the horizontal direction along the rail on the tensile test slide rail 25. One end of a spring portion 23b is attached to the gauge body 23a, and the degree of expansion / contraction due to the load of the spring portion 23b is measured as a force. A vertical peeling force evaluation test jig 24 (hereinafter abbreviated as “jig 24”) is attached to the other end of the spring portion 23b. A gelled elastic resin composition 22 having an appropriate size is used as a test piece, which is fixed to the tip of a jig 24. Next, the test piece 22 made of an elastic resin composition fixed to the jig 24 is pressed against the resin bonding wall 21 perpendicular to the horizontal plane with an appropriate force to be lightly bonded. The digital push-pull gauge 23 is pulled horizontally with a force F, and the test piece 22 is peeled off from the resin bonding wall 21. The tensile force at the time of peeling is measured by the gauge body 23a, and the value is converted per unit area (1 cm ² ). This converted value is defined as the vertical peeling force.

It is the whole schematic figure of the state which has inject | poured the solution-like elastic resin composition RS into the rear wheel WR of the existing bicycle B using the resin injection apparatus provided with the pump 1. FIG. It is a fragmentary sectional view along the circumferential direction of a tire which shows change of air bubbles 13 mixed in tire tube 12 at the time of filling of solution-like elastic resin composition RS which does not have adhesive strength after gelation. It is a fragmentary sectional view along the circumferential direction of a tire which shows change of bubble 13 mixed in tire tube 12 at the time of filling of solution-like elastic resin composition RS which has adhesive strength after gelation. It is the table | surface which showed the evaluation result of the Example and the comparative example. It is the schematic of a vertical peeling force evaluation test.

Explanation of symbols

F: Tensile force
RS: Solution resin (solution elastic resin composition)
RS ′: elastic resin composition after gelation
V: Valve
1: Pump
2: Solution resin container
3: Resin injection tube
12: Tire tube
13: Bubble
16: Crack
17: Air pocket
21: Resin adhesive wall
22: Specimen consisting of elastic resin composition
23: Digital push-pull gauge
23a: Gauge body
23b: Spring part

Claims (2)

An elastic resin composition for filling a tire tube that is injected and filled into a tire tube via a tire air injection valve,
It contains 10 to 20% by weight of a styrenic thermoplastic elastomer, 5 to 15% by weight of a tackifier, 65 to 85% by weight of process oil, and has a melt viscosity of 10 cP to 300 P at a melting temperature of 160 ° C. An elastic resin composition for filling tire tubes. The elastic resin composition for filling a tire tube according to claim 1, wherein the gelled resin composition has a vertical peeling force at room temperature of 0.1 to 0.5 N / cm ² .

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