Puncture-proof tire filler and method for manufacturing the same

Abstract

The objective is to provide a puncture-proof tire filler with high rebound elasticity and a comfortable ride. [Solution] A puncture-proof tire filler 10, which is housed in an annular space formed by a tire outer shell 20 and a rim 25, is formed by a prepolymer method using a composition that includes a prepolymer made from a composition comprising a polyisocyanate comprising at least one of 1,5-naphthalene diisocyanate (NDI) and 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), and a polyol containing more than 90 parts by weight of polytetramethylene glycol in 100 parts by weight of polyol.

Description

Technical Field

[0001] The present invention relates to a filler for a non-puncture tire and a method for manufacturing the same.

Background Art

[0002] As a non-puncture tire that does not puncture even when a tire of a bicycle or the like is punctured by nails, instead of an air tube into which air is press-fitted, there is one in which a filler for a non-puncture tire is housed in an annular space formed by a tire outer skin and a rim (Patent Document 1, Patent Document 2).

[0003] In Patent Document 1, a filler for a non-puncture tire is proposed, which is composed of an elastic foam of closed cells formed into a circular cross-section mainly composed of butyl rubber or halogenated butyl rubber, and a solid film mainly composed of butyl rubber or halogenated butyl rubber integrally formed on the outer peripheral surface of the elastic foam. In Patent Document 2, a filler for a non-puncture tire composed of a foamed styrene elastomer is proposed. However, conventional non-puncture tires are further required to have higher resilience and better riding comfort.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above points, and an object thereof is to provide a novel filler for a non-puncture tire having high resilience and good riding comfort and a method for manufacturing the same.

Means for Solving the Problems

[0006] The first embodiment is a puncture-proof tire filler housed in an annular space formed by a tire sheath and a rim, characterized in that it is formed by a prepolymerization method using a composition that includes a urethane prepolymer made from a composition comprising a polyisocyanate comprising at least one of 1,5-naphthalene diisocyanate (NDI) and 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), and a polyol containing more than 90 parts by weight of polytetramethylene glycol per 100 parts by weight of polyol.

[0007] The second aspect is a density (according to JIS 6268) of 0.2 to 0.5 g / cm³. 3 It is characterized by being such.

[0008] The third embodiment is a method for manufacturing a puncture-proof tire filler according to the first or second embodiment, characterized in that a composition containing the urethane prepolymer is placed in a mold and a urethane elastomer is formed by a prepolymerization method.

[0009] A fourth aspect is characterized in that, in the third aspect, the polytetramethylene glycol has a weight-average molecular weight of 1500 to 3500.

[0010] The fifth embodiment is characterized in that, in the third embodiment, the amount of the composition containing the urethane prepolymer added to the mold is 20 to 60 vol% of the cavity volume of the mold.

[0011] A sixth aspect is a composition comprising the urethane prepolymer to the mold in the fourth aspect. The amount of the material to be added is characterized by being 20 to 60 vol% of the cavity volume of the mold.

[0012] The seventh aspect is a urethane elastomer with a rebound modulus (in accordance with JIS K6255) of 80% or more. This is a puncture-proof tire filler made of Mar. [Effects of the Invention]

[0013] According to the present invention, a filler for a non-puncture tire with high resilience and good riding comfort can be obtained.

Brief Description of the Drawings

[0014] [Figure 1] It is a partial cross-sectional perspective view of a filler for a non-puncture tire according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view showing an annular space composed of a tire outer skin and a rim and a filler for a non-puncture tire. [Figure 3] It is a table showing the configurations and physical properties of Examples and Comparative Examples.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described. The filler 10 for a non-puncture tire shown in FIG. 1 is accommodated in an annular space 27 composed of a tire outer skin 20 such as a bicycle tire and a rim 25 as shown in FIG. 2. The tire outer skin 20 and the rim 25 can be those used for ordinary bicycles using an inner tube.

[0016] The filler 10 for a non-puncture tire of the present invention is composed of a urethane elastomer formed by a prepolymer method using a composition containing a urethane prepolymer prepared from a composition containing a polyisocyanate and a polyol, and has a substantially circular cross-sectional shape that can be accommodated in the annular space 27.

[0017] The filler 10 for a non-puncture tire is not limited to being pre-formed into an annular shape, and a plurality of divided bodies or a single formed body formed into a predetermined length of a linear or arc shape may be accommodated in the annular space 27 to form an annular shape. When the filler 10 for a non-puncture tire is composed of a plurality of divided bodies, the divided bodies adjacent to each other in the annular space 27 may be joined by adhesion or the like, or may simply have their end faces adjacent to each other without adhesion.

[0018] ​For the urethane prepolymer, at least one isocyanate of 1,5-naphthalene diisocyanate (NDI) and 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI) is used. More preferably, NDI is used alone.

[0019] Also, for the polyol of the urethane prepolymer, a polyol containing polytetramethylene glycol (PTMG) in an amount exceeding 90 parts by weight per 100 parts by weight of the polyol is used. More preferably, PTMG is used alone. By containing polytetramethylene glycol in an amount exceeding 90 parts by weight per 100 parts by weight of the polyol, the resilience of the filler 10 for the non-puncture tire can be increased, and the riding comfort can be improved. Also, high hydrolysis resistance, physical strength, and excellent general physical properties such as strain characteristics can be expected. Since water such as rainwater may enter the annular space 27 from the gap between the tire outer skin 20 and the rim 25 during use of the non-puncture tire filler 10 and come into contact with the non-puncture tire filler 10, if the hydrolysis resistance is not high, the durability will decrease. The weight average molecular weight of polytetramethylene glycol is preferably 1500 to 3500. By using polytetramethylene glycol with a weight average molecular weight of 1500 to 3500, the resilience can be made higher.

[0020] When the amount of polytetramethylene glycol contained in 100 parts by weight of the polyol is less than 100 parts by weight, as the remaining polyol used together with polytetramethylene glycol, one or more polyols having a weight average molecular weight of 1000 to 3000 and a functionality of 2 are used. Examples of the polyol having a weight average molecular weight of 1000 to 3000 and a functionality of 2 include polyethylene glycol, polypropylene glycol, polycaprolactone polyol, polycarbonate polyol, and the like.

[0021] This document describes the manufacturing process of a puncture-proof tire filler 10 using a prepolymer method. Step 1: A urethane prepolymer is prepared from a composition containing the polyisocyanate and the polyol. Specifically, the polyol is reacted with a stoichiometrically excess of the polyisocyanate to produce a urethane prepolymer (Solution B) having isocyanate groups at the ends with an isocyanate content of 3 to 10% by weight. A surfactant such as a silicone-based foam stabilizer may be added at this stage.

[0022] Step 2: A composition containing urethane prepolymer (liquid B) is poured into a mold to produce a filler for puncture-proof tires. Specifically, at least one foaming solution (Solution A) selected from aliphatic diols, trifunctional polyols, water, mixtures thereof, and aromatic diamines having two preferably primary hydroxyl groups and a weight-average molecular weight of 56 to 210 g / mol, is mixed with the urethane prepolymer (Solution B) in an amount such that the ratio of mol% of isocyanate groups in the urethane prepolymer (Solution B) to mol% of hydroxyl groups in the foaming solution (Solution A), i.e., the value of [mol% of isocyanate groups in Solution B / mol% of hydroxyl groups in Solution A] is 1.0 to 1.3. The mixture is then poured into a mold having a cavity for a puncture-proof tire filler, and the molded product is demolded after reaction curing. A foam stabilizer, surfactant, or antioxidant may be added to the foaming solution (Solution A) as needed. The amount of mixture to be added to the mold varies depending on the amount of water that functions as a foaming agent and the foaming ratio which is correlated with the amount of water added. However, from the standpoint of balancing the lightness and strength (durability) of the filler for puncture-proof tires, an amount of 20 to 60 vol% of the volume of the mold cavity is preferable.

[0023] Examples of aliphatic diols used in the second step include 1,4-butanediol, ethylene glycol, diethylene glycol, 1,6-hexanediol, ethoxylated hydroquinone, and cyclohexanediol. Examples of aromatic diamines include methylenebis-o-chloroaniline, 3,5-diamino-p-chloroisobutylbenzoate, and trimethylene glycol-di-p-aminobenzoate. For foam stabilizers, those known for use with urethane elastomers can be used. Examples include silicone-based foam stabilizers and fluorine-containing compound-based foam stabilizers. Surfactants and antioxidants known for use with urethane elastomers can be used.

[0024] The puncture-proof tire filler 10 of the present invention has a density (according to JIS K6268) of 0.2 to 0.5 g / cm³ from the viewpoint of lightness. 3 It is preferable. Furthermore, the puncture-proof tire filler 10 of the present invention can be manufactured by a prepolymer method from a composition containing the urethane prepolymer, thereby achieving a rebound modulus (in accordance with JIS K6255) of 80% or more, and improving the riding comfort of bicycles and the like equipped with this puncture-proof tire filler 10.

[0025] The puncture-proof tire filler 10 of the present invention preferably has a surface hardness (Asker C hardness, compliant with JIS K6253) of 50 to 60. If the surface hardness (Asker C hardness) is too low, the tire resistance during driving will increase, and if it is too high, the impact caused by unevenness in the road surface will be greater. The puncture-proof tire filler 10 of the present invention preferably has a tensile strength (according to JIS K6251) of 2.0 MPa or more.

[0026] Furthermore, the puncture-proof tire filler 10 of the present invention preferably has a viscoelasticity (tanδ / 20℃) of 0.025% or less, and more preferably 0.02% or less, as measured by ARES-G2 TA Instruments under test conditions of temperature range: -100 to 100℃, heating rate: 6℃ / min, mode: parallel plate mode, strain: 0.5%, and frequency: 1Hz. As the viscoelasticity (tanδ / 20℃) decreases, the rebound elasticity increases, resulting in a smoother ride and reduced rolling resistance. This allows for less pedaling force when using a bicycle or other vehicle equipped with the puncture-proof tire filler 10, making for a more comfortable ride. [Examples]

[0027] Examples and comparative examples of the present invention are described below. <1st process> A urethane prepolymer (solution B) was prepared using the following polyol and polyisocyanate in the formulation shown in Figure 3. [Polyol] • PTMG-1: Polytetramethylene glycol, weight-average molecular weight 2000, product name: PTMG2000, manufactured by Mitsubishi Chemical Corporation. • PTMG-2: Polytetramethylene glycol, weight-average molecular weight 3000, product name: PTMG3000, manufactured by Mitsubishi Chemical Corporation. • PPG: Polypropylene glycol, weight-average molecular weight 2000, Product name: Primepol FH2202, manufactured by Sanyo Chemical Industries, Ltd. [Polyisocyanate] • 1,5-Naphthalene diisocyanate (NDI), product name: Desmodur 15, manufactured by Sumika Bayer Urethane Co., Ltd.

[0028] [Preparation of urethane prepolymers] A specified amount of polyol (corresponding to the ratio of polyol and polyisocyanate shown in Figure 3) is added to a 20L metal reaction vessel, and the temperature is controlled to 130°C. With the reaction vessel maintained at 130°C, a specified amount of polyisocyanate (corresponding to the ratio of polyol and polyisocyanate shown in Figure 3) is added and stirred for 20 minutes. By leaving the reaction vessel at room temperature and allowing it to cool slowly, a urethane prepolymer having isocyanate groups at its ends is produced.

[0029] <Second process> Using the prepared urethane prepolymer (liquid B) and foaming liquid (liquid A), molded products (test pieces) for physical property measurement were manufactured as follows. [Foaming liquid] The foaming solution (Solution A) was prepared by mixing a foaming agent containing castor oil and water in a 1:1 ratio with an amine catalyst (amine catalyst, product name: Addocat PP, manufactured by Rhein Chemie) in the proportions shown in Figure 3.

[0030] [Manufacturing of molded products] A urethane prepolymer (liquid B) heated to 80°C and a foaming liquid (liquid A) heated to 40°C were mixed according to the ratio of urethane prepolymer to foaming liquid shown in Figure 3, and stirred and mixed using a low-pressure injection machine. 330g of the mixture (target density 0.5g / cm³) was then prepared. 3 The mixture is placed into a mold (200 x 110 x 30 mm) that has been preheated to 80°C, and cured for 30 minutes (primary curing). After curing (primary curing), the product is removed from the mold and cured again (secondary curing) at 100°C for 12 hours to obtain the molded product.

[0031] <Measurement of physical properties> Density (according to JIS K6268), rebound modulus (according to JIS K6255), surface hardness (Asker C hardness, according to JIS K6253), tensile strength (according to JIS K6251), and tanδ / 20℃ were measured for the molded products. The measurement conditions for tanδ / 20℃ were as described above. For rebound modulus and surface hardness, measurements were taken at three different locations on the molded product, and the difference between the maximum and minimum values ​​measured at these three locations was defined as variability. For rebound modulus variability, values ​​less than 3% were judged as "○" and values ​​of 3% or more were judged as "×". For surface hardness variability, values ​​less than 3 were judged as "○" and values ​​of 3 or more were judged as "×".

[0032] • Example 1 Example 1 is an example in which a urethane polymer was prepared using polytetramethylene glycol with a weight-average molecular weight of 2000 as the polyol and 1,5-naphthalene diisocyanate as the polyisocyanate. The physical properties of the molded product in Example 1 are as follows: density of 0.30 g / cm³ 3 The rebound modulus was 81-82%, the variation in rebound modulus was 1%, the variation in rebound modulus was judged as "○", the surface hardness (Asker C hardness) was 55-56, the variation in surface hardness was 1, the variation in surface hardness was judged as "○", the tensile strength was 2.7 MPa, and tanδ / 20℃ was 0.0193%. The molded product of Example 1 is lightweight, has good resilience, and exhibits little variation in rebound modulus and surface hardness. Furthermore, because the value of tanδ / 20℃ is small, it has low rolling resistance. In bicycles and the like fitted with the puncture-proof tire filler made with the configuration of Example 1, the good rebound elasticity results in a comfortable ride, and the low rolling resistance allows for less pedaling force, resulting in a comfortable ride.

[0033] • Example 2 Example 2 is an example in which a urethane polymer was prepared using polytetramethylene glycol with a weight-average molecular weight of 3000 as the polyol and 1,5-naphthalene diisocyanate as the polyisocyanate. The physical properties of the molded product in Example 2 are as follows: density of 0.30 g / cm³ 3 The rebound modulus was 84-85%, the variation in rebound modulus was 1%, the variation in rebound modulus was judged as "○", the surface hardness (Asker C hardness) was 52-53, the variation in surface hardness was 1, the variation in surface hardness was judged as "○", the tensile strength was 2.5 MPa, and tanδ / 20℃ was 0.0185%. The molded product of Example 2 is lightweight, has good resilience, and exhibits little variation in rebound modulus and surface hardness. Furthermore, because the value of tanδ / 20℃ is small, it has low rolling resistance. In bicycles and the like fitted with the puncture-proof tire filler made with the configuration of Example 2, the good rebound elasticity results in a comfortable ride, and the low rolling resistance allows for less pedaling force, resulting in a comfortable ride.

[0034] • Comparative Example A comparative example is a urethane polymer prepared using polytetramethylene glycol and polypropylene glycol with a weight-average molecular weight of 2000 in a weight ratio of 85:15 as the polyol, and 1,5-naphthalene diisocyanate as the polyisocyanate. The physical properties of the comparative example molded product were a density of 0.38 g / cm³. 3 The rebound modulus was 76-79%, the variation in rebound modulus was 3%, and the variation in rebound modulus was judged as "×". The surface hardness (Asker C hardness) was 59-62, the variation in surface hardness was 3, and the variation in surface hardness was judged as "×". The tensile strength was 2.4 MPa, and tanδ / 20℃ was 0.0276%. The molded product of the comparative example has a higher density, lower resilience, and greater variation in rebound modulus and surface hardness compared to Examples 1 and 2. Furthermore, it exhibits a higher tanδ / 20°C value and greater rolling resistance compared to Examples 1 and 2.

[0035] As described above, the puncture-proof tire filler of the present invention has high rebound elasticity and provides a comfortable ride. Furthermore, the present invention is not limited to the embodiments described herein and can be modified without departing from the spirit of the invention. [Explanation of Symbols]

[0036] 10. Inflatable tires for puncture-proof tires 20 Tire outer layer 25 rim 27. Ring-shaped space

Claims

1. A puncture-proof tire filler that is housed in an annular space formed by the tire sheath and the rim, A polyisocyanate comprising at least one of 1,5-naphthalene diisocyanate (NDI) and 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), A polyol containing more than 90 parts by weight of polytetramethylene glycol in 100 parts by weight of the polyol, A filler for puncture-proof tires, characterized by being formed by a prepolymerization method using a composition containing a urethane prepolymer made from a composition containing the above.

2. Density (according to JIS K6268) is 0.2 to 0.5 g / cm³ ３ The puncture-proof tire filler according to claim 1, characterized in that it is the same as described in claim 1.

3. In the method for manufacturing a puncture-proof tire filler according to claim 1 or 2, A method for producing a filler for puncture-proof tires, characterized by introducing a composition containing the aforementioned urethane prepolymer into a mold and forming a urethane elastomer by a prepolymerization method.

4. The method for producing a filler for puncture-proof tires according to claim 3, characterized in that the polytetramethylene glycol has a weight-average molecular weight of 1500 to 3500.

5. The method for producing a puncture-proof tire filler according to claim 3, characterized in that the amount of composition containing the urethane prepolymer added to the mold is 20 to 60 vol% of the cavity volume of the mold.

6. The method for producing a filler for puncture-proof tires according to claim 4, characterized in that the amount of composition containing the urethane prepolymer added to the mold is 20 to 60 vol% of the cavity volume of the mold.

7. A puncture-proof tire filler made of urethane elastomer with a rebound modulus (compliant with JIS K6255) of 80% or higher.

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