JPH0377082B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is mainly composed of a thermoplastic polyurethane elastomer, which is blended with a synthetic resin having higher gas barrier properties than the thermoplastic polyurethane elastomer. Regarding tubes for motorcycles that are excellent in quality. [Conventional technology] In recent years, the tubes of automobiles, motorcycles, etc.
Regarding tubes made of thermoplastic polyurethane elastomer, which have many excellent properties such as elasticity, flexibility, abrasion resistance, aging resistance, and mechanical strength, in place of tubes made of natural rubber latex or butyl rubber, which have been widely used in the past. has been reported. (For example, JP-A-54-122507, JP-B-56-39805) However, as is well known, thermoplastic polyurethane elastomer costs much more than conventional natural rubber latex or butyl rubber.
In order to adopt it for general bicycles, motorcycles, etc., it is essential to first reduce the cost problem. Therefore, in order to reduce the cost of tubes made of thermoplastic polyurethane elastomer, a method of making the tube thinner has been proposed. As a result, the air retention properties are further significantly reduced, and its practicality as a tube for two-wheeled vehicles is in question.Currently, no product has yet been found that is satisfactory in terms of cost performance. (Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to solve the problems that have hitherto been considered a major obstacle in reducing the cost of thermoplastic polyurethane elastomer tubes. The object of the present invention is to provide a tube for two-wheeled vehicles that is extremely practical and improves the problem of air retention. (Means for Solving the Problems) As a specific means for improving the air retention problem of tubes made of thermoplastic polyurethane elastomer, the present inventors conducted intensive research on the blending effect with other synthetic resins. Performances required for this type of tube, such as the properties that thermoplastic polyurethane elastomer tubes have, such as moldability for adhesion of valve rubber seats and tube jointing, elasticity, durability, running safety, etc. In order to improve the air retention problem without compromising the many special performance requirements of polyurethane, it is essential to blend a specific proportion of a synthetic resin that can be blended with at least the thermoplastic polyurethane elastomer and has excellent gas barrier properties. They reached the conclusion that the method is effective and most practical, and completed the present invention. That is, the present invention mainly uses a thermoplastic polyurethane elastomer selected from the group of polyvinyl chloride resins, polyvinylidene chloride resins, polyester resins, polyamide resins, ethylene-vinyl alcohol copolymer resins, and acrylic resins. A tube for a two-wheeled vehicle having excellent air retention properties, characterized in that it is made of a blended resin of a synthetic resin having a higher gas barrier property than the thermoplastic polyurethane elastomer, which is made of a combination of one or more of the above thermoplastic polyurethane elastomers. . Hereinafter, the configuration and effects of the tube for two-wheeled vehicles with excellent air retention properties of the present invention will be explained in detail. The thermoplastic polyurethane elastomer used in the present invention is a general term for rubber-like elastic polymers containing urethane groups in the molecular structure whose main raw materials are bifunctional polyol, diisocyanate, and glycol, and which have thermoplasticity. Specifically, it includes thermoplastic polyurethane elastomers such as adipate ester type, caprolactone ester type, and polycarbonate ester type, which are distinguished depending on the type of raw material such as the polyol used, but among these, water-resistant Polyether-based thermoplastic polyurethane elastomers are preferred, as they have excellent properties and weather resistance, and have relatively low permanent elongation. Although such thermoplastic polyurethane elastomers are generally amorphous, crystalline thermoplastic polyurethane elastomers may be used alone or in combination to improve air retention properties. Additionally, appropriate additives such as lubricants, ultraviolet absorbers, antioxidants, colorants, anti-blocking agents, and hydrolysis inhibitors may be added as necessary. On the other hand, the synthetic resin to be blended with the thermoplastic polyurethane elastomer must be able to improve the air retention properties of the resulting tube, so it can essentially be blended with the thermoplastic polyurethane elastomer and has gas barrier properties. must be superior to the thermoplastic polyurethane elastomer. Synthetic resins that satisfy these properties include polyvinyl chloride resins, polyvinylidene chloride resins, and polyester resins based on the measured values of the compatibility of thermoplastic polyurethane elastomers with various resins and air permeability coefficients shown in Table 1. , polyamide resins, ethylene-vinyl alcohol copolymer resins, acrylic resins, polycarbonate resins, polyvinyl butyral resins (these resins also include so-called elastomers, which are rubber-like products of these resins). Examples include those made of one or more selected combinations, and among these, polyvinyl chloride resins with an air permeability coefficient of 2c.c.・mm/cm ²・sec・cmHg・10 ¹⁰ or less are exemplified. , polyvinylidene chloride resins, polyester resins, polyamide resins, ethylene-vinyl alcohol copolymer resins, acrylic resins, and their elastomers can exhibit high air retention with a small blend ratio, so these resins can be used. There must be. Any of these synthetic resins can be blended with the thermoplastic polyurethane elastomer, but since the thermoforming temperature of thermoplastic polyurethane elastomer is usually 150 to 200°C, the synthetic resin used in the present invention is also blended at a temperature of 150 to 200°C.
It is more preferable to appropriately copolymerize the material so that it can be thermoformed at a certain level.

【table】

[Table] The tube for motorcycles with excellent air retention properties of the present invention is made by blending a thermoplastic polyurethane elastomer with a synthetic resin having higher gas barrier properties. Generally, if the blend ratio of synthetic resin is too large, the excellent adhesion properties of thermoplastic polyurethane elastomer due to high frequency or heat will be inhibited, resulting in problems such as poor adhesion of valve rubber seats or poor connection of tubes during tube bonding process. In addition to this, the adhesion of the patch rubber also deteriorates when repairing punctures. Furthermore, if the blend ratio of the synthetic resin in the tube material is small, improvement in air retention cannot be expected. Therefore, the blend ratio of the thermoplastic polyurethane elastomer and the synthetic resin whose air barrier property is higher than that of the thermoplastic polyurethane elastomer is 50 to 99% by weight, preferably 70 to 95% by weight, and 1 to 50% by weight, preferably 70 to 95% by weight, for the latter. is 5 to 30% by weight. In addition, the blend ratio of the synthetic resin is determined by the permanent elongation and 100% modulus (at the time of elongation) of the resulting tube.
When measured by the method specified in JISK6301, the permanent elongation is 40% or less, preferably 30% or less, and
It should be determined so as to satisfy the requirements of 100% (when stretched) modulus of 150 Kg/cm ² or less, preferably 120 Kg/cm ² . These permanent elongations and 100
% (at elongation) modulus, first blend the resins you want to use in a predetermined ratio, then test the blended resin to form films at various temperatures, and each tube produced has a permanent elongation. and 100% (at the time of elongation) modulus was measured, and the temperature at the time of manufacture of the tube with the value corresponding to the above conditions was investigated, and then the film was formed under these temperature conditions,
The desired tube is obtained. The reason why the permanent elongation and 100% modulus (at the time of extension) must be determined within the above range is that the present invention provides excellent running performance even under harsh conditions such as impact, twisting, and repeated compressive loads during running. Tubes for motorcycles require stability (to avoid falling or falling even when running on pebbles or uneven surfaces), and the elasticity and flexibility of the tubes improve the riding feel. The smaller the permanent elongation, which is an index of elasticity, and the 100% (when stretched) modulus, which is an index of flexibility, both have a very large effect on running stability, the better the running feeling and ride based on soft cushioning properties. Therefore, if either the permanent elongation or the 100% modulus (at the time of extension) deviates from the above range, vibrations may increase or the cushioning properties may deteriorate, resulting in poor running feel and This is because running stability is significantly deteriorated and it becomes difficult to apply stress to the tube for a two-wheeled vehicle. Furthermore, since the motorcycle tube of the present invention is mainly made of thermoplastic polyurethane elastomer, it has far superior mechanical properties and heat resistance, cold resistance, and resistance compared to conventional natural rubber latex or butyl rubber tubes. It has many excellent features including ozone properties. Furthermore, the tube for motorcycles of the present invention is economically superior because the synthetic resin for blending is relatively inexpensive and can be easily manufactured with a single extruder. These conventional technologies make it possible to easily and reliably perform the process of adhering the valve rubber seat by bringing the front and back surfaces or cross-sections of the tube into contact with each other, joining the tube, and applying patch rubber when repairing punctures. It has the following advantages. (Examples) Hereinafter, in order to make it easier to understand the tube for a two-wheeled vehicle having excellent air retention properties of the present invention, the present invention will be explained in detail using Examples, but the present invention is not limited to these Examples. The physical properties of the tube for motorcycles having excellent air retention properties of the present invention were measured and evaluated as follows. (1) Air retention rate (unit: %) After filling the tube with air so that the internal pressure was approximately 8 kg/cm ² , the change in internal pressure over time was expressed as the retention rate using the following formula. Air retention rate = Tube internal pressure after aging / Initial tube internal pressure x 100 The standard value for passing/failing air retention rate is that after 10 days, the air retention rate is 1% or more higher than that of polyurethane elastomer alone without resin blending. , and after 30 days, those whose air retention rate is 10% or more higher than that of the polyurethane elastomer alone are considered to be passed, and those which are not are judged to be rejected. (2) Permanent elongation (unit: %) Measured by the method specified in JISK6301-1975. The permanent elongation specified here is measured by pulling the test piece to a length equivalent to approximately 1/2 of the elongation (%), holding it for 10 minutes, then suddenly shrinking it without bouncing back, and measuring after 10 minutes. be. Permanent elongation is calculated using the following formula. PS=l ₁ −L ₀ /L ₀ ×100 where PS: Permanent elongation (%) L ₀ : Gauge distance (mm) l ₁ : Length between the gauge lines after shrinking and leaving for the specified time (mm) ( 3) 100% (when stretched) modulus (unit: Kg/cm ² )
A tensile test was performed according to the method specified in JISK6301-1975, and the load at 100% extension (unit: Kg)
It was calculated from the cross-sectional area of the test piece (unit: cm ² ) using the following formula. Modulus at 100% (at extension) = load at 100% extension/cross-sectional area of test specimen (4) Adhesion processability of tubes When adhering tubes, we checked the adhesion of the valve rubber seat using a high-frequency welder and the jointability of the tubes. It was mainly evaluated,
Those that could be processed without any problems were marked as (○), and those in which poor adhesion was observed in either the valve rubber seat adhesion or the tube joint were marked as (x). (5) Running stability A product with a permanent elongation of 40% or less and a 100% (when stretched) modulus of 150Kg/cm ² or less is considered to have running stability. (6) Comprehensive evaluation This is a comprehensive evaluation of the suitability of tubes for motorcycles based on measurement results such as air retention, permanent elongation, 100% (when stretched) modulus, and tube adhesive workability. Those that are suitable are marked as (◎), those that are suitable are marked as (○), and those that are unsuitable are marked as (×). Examples 1 to 5, Comparative Examples 1 to 3 The difunctional polyol component was polytetramethylene glycol, the diisocyanate component was 4.4' diphenylmethane diisocyanate, and the glycol component was
80% by weight of polyether-based thermoplastic polyurethane elastomer raw material made of 1.4-butanediol (“Elastlan” E380 manufactured by Nippon Elastran Co., Ltd.)
A mixed raw material containing 20% by weight of various synthetic resin raw materials shown in Table 2 was fed to a 50φ extruder and melted and kneaded at a temperature of 160 to 190℃, resulting in a lip diameter of 17.2φ with an extrusion rate of about 20Kg/hr. extruded into a tube shape from an annular die,
By pulling at a speed of approximately 8.5m/min,
A tube of 27mm and 600μ thick was created. In addition, for comparison, we used the same polyurethane elastomer raw material as above, and the folded diameter was 27 mm and the thickness was 700 μm.
A tube was prepared (Comparative Example 1). For the tubes obtained in these Examples and Comparative Examples, the evaluation results of air retention, permanent elongation, modulus at 100% (when stretched), adhesive workability of the tubes, etc. are shown in Table 2. It has become clear that a tube made of a blend of synthetic resin with better gas barrier properties than polyurethane elastomer has excellent air retention, running stability, and tube adhesion processability, and is extremely suitable as a tube for two-wheeled vehicles.

[Table] Examples 6 to 9, Comparative Examples 4 to 6 Folded diameter 27 mm, thickness
A 600μ tube was created. For tubes with different blend ratios, air retention, permanent elongation, 100% (when stretched)
The evaluation results of modulus, tube adhesion processability, etc. are shown in Table 3. From the table, the blend ratio of thermoplastic polyurethane elastomer and polyester resin, permanent elongation, 100% (when stretched) modulus, etc. of the present invention are shown in Table 3. It has become clear that the tubes in this range have excellent air retention, running stability, and tube adhesion processability, and are extremely suitable as tubes for two-wheeled vehicles.

[Table] Examples 10 to 13, Comparative Examples 7 to 9 Polyether-based crystalline thermoplastic polyurethane elastomer ("Elastlan" B385 manufactured by Nippon Elastran Co., Ltd.) was used as the thermoplastic polyurethane elastomer, and examples were used as the synthetic resin. Using the same ethylene vinyl alcohol copolymer resin as used in step 4, mixed raw materials with various blend ratios of both were supplied to a 50φ extruder and heated to 170 to 190℃.
A tube with a broken diameter of 35 mm and a thickness of 900 μm is produced by melt-kneading at a temperature of It was created. For tubes with different blend ratios, air retention, permanent elongation, 100% (when stretched)
The evaluation results of modulus, tube adhesion processability, etc. are shown in Table 4. From the table, the blend ratio of thermoplastic polyurethane elastomer and ethylene vinyl alcohol copolymer resin, permanent elongation, 100% modulus stress, etc. of the present invention are shown in Table 4. It has become clear that the tubes in this range have excellent air retention, running stability, and tube adhesion processability, and are extremely suitable as tubes for two-wheeled vehicles.

[Table] Examples 14 to 17, Comparative Examples 10 to 11 Raw materials prepared by mixing the same thermoplastic polyurethane elastomer and thermoplastic polyamide elastomer (Toray Pebax 2533) used in Example 1 at various blend ratios were put into a 50φ extruder. Supply 160~180
The mixture was melt-kneaded at a temperature of 0.degree. C., extruded into a tube at an extrusion rate of about 25 kg/hr, and taken off at a speed of about 10 m/min to produce a tube with a folded diameter of 30 mm and a thickness of 600 .mu.m. For tubes with different blend ratios, air retention, permanent elongation, 100% (when stretched)
The evaluation results of modulus, tube adhesion processability, etc. are shown in Table 5. From the same table, it can be seen that tubes with blend ratio of thermoplastic polyurethane elastomer and polyamide elastomer, permanent elongation, 100% modulus stress, etc. are within the range of the present invention. It has become clear that the material has excellent air retention properties, running stability, and tube adhesion processability, and is extremely suitable as a tube for two-wheeled vehicles.

[Table] Represents.
(Effects of the Invention) The tube for motorcycles of the present invention as described above has superior air retention properties compared to conventional tubes made only of thermoplastic polyurethane elastomer, and is indispensable for this type of tube. This tube combines the excellent running stability, tube adhesion workability, and puncture repairability of the tube. Furthermore, the tube for motorcycles of the present invention has excellent air retention properties as described above, so in addition to the noteworthy feature that it is possible to reduce costs and weight by making the tube thinner, it also has the unique characteristics of thermoplastic polyurethane elastomer. It is extremely promising as a substitute material for conventional natural rubber latex or butyl rubber tubes because its heat resistance, cold resistance, ozone resistance, abrasion resistance, etc. greatly extend the useful life of the tube, and its industrial value is high. It's really a huge amount.

Claims (1)

[Claims] 1 Mainly thermoplastic polyurethane elastomer, polyvinyl chloride resin, polyvinylidene chloride resin, polyester resin, polyamide resin, ethylene-vinyl alcohol copolymer resin,
Excellent air retention, characterized by being made of a blended resin blended with a synthetic resin having a higher gas barrier property than the thermoplastic polyurethane elastomer, which is made of one or more combinations selected from the group of acrylic resins. tube for two-wheeled vehicles.