JP2979247B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a rim assembly which is a drawback of this type of bead ring while using a fiber-reinforced resin composite material as a bead ring disposed at a bead portion for reducing the weight of a tire. The present invention relates to a pneumatic tire having improved properties and durability.

[0002]

2. Description of the Related Art It has become clear that the greatest factor of global warming in recent years depends on carbon dioxide emission caused by petroleum fuel consumption. Above all, the influence of vehicle exhaust gas is very large, and there is an urgent need to reduce exhaust gas, that is, to reduce the fuel consumption of vehicles.

In order to achieve low fuel consumption in automobiles,
Weight reduction of tires is an effective means. However, simply reducing the weight of each member of the tire not only reduces the durability, but also reduces the basic performance of the tire such as steering stability and uniformity. Therefore, it is extremely difficult to reduce the weight of each member while maintaining the basic performance of the tire.

In order to reduce the weight of the tire under these difficult conditions, a tire using a new lightweight material having basic performance comparable to that of a conventional member has been proposed. For example, Japanese Patent Application Laid-Open No. 57-66007 discloses that a high modulus fiber bundle of inorganic material is impregnated with a thermosetting resin or liquid rubber as a matrix in place of steel wire of a bead member, formed into a predetermined shape, and then heat cured. There has been proposed a pneumatic tire using the above as a bead ring. As a result of intensive studies conducted by the present inventors, it has been found that the higher the rigidity of the matrix, the better the durability of such a bead. It has been found that when the rigidity of the matrix is increased with such a bead, the bead annular body (bead portion) becomes rigid, which deteriorates the rim assemblability of the tire and makes it difficult to apply the current rim.

[0005] Japanese Utility Model Application Laid-Open No. 64-16901 discloses a fiber-reinforced resin composite material composed of carbon fiber and a thermosetting resin, which has a relatively thick, circular, rectangular flat plate or polygonal cross section. A bead ring is disclosed which is formed into a linear body having a predetermined strength by imparting a predetermined strength by winding the wire in a required number of times, and then winding a wrapping tape. However, since this bead ring is rigid and poor in flexibility, it is easily broken in a tire manufacturing process, and good rim assemblability cannot be obtained. In addition, there is a disadvantage that the strength is impaired due to wear between the linear bodies made of a fiber reinforced resin composite material (hereinafter, referred to as FRP), resulting in poor durability.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a tire having improved durability while using a bead ring formed from FRP comprising non-metallic fiber filaments and a thermoplastic resin, and having a basic steering stability and the like. An object of the present invention is to provide a pneumatic tire having improved performance and rim assembly.

[0007]

The present invention for achieving the above object has a specific gravity of less than 3.0 and a tensile strength of 150 kgf /
mm ² or more, a tensile modulus of 4000 kgf / mm ² or more multiple code-like fiber bundles formed of non-metallic fiber filaments of the tensile modulus as the matrix is 10 kgf / mm ²
15% by weight or more of the above thermoplastic resin is impregnated and adhered to form a linear body made of a fiber reinforced resin composite material having a wire diameter of 0.7 mm to 2.0 mm, and a plurality of the linear bodies have a volume fraction of 0. .3
The bead ring is constituted by being embedded in rubber in the range of 0.8 to 0.8.

[0008] By adopting a structure in which the FRP linear body is buried in the rubber as described above, it is possible to reduce the weight based on the FRP linear body, and to improve the durability and the rim assemblage, which have been disadvantages in the past. to enable. In the present invention, the tensile strength and the tensile modulus of the cord-like fiber bundle are values measured according to the method specified in JIS R7601. The tensile modulus of the thermoplastic resin refers to a value measured according to a method specified in ASTM D638.

The configuration of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a bead ring of the tire of the present invention.
The RP linear member 3 is rubber. The bead ring 1 has a plurality of
It has a structure in which the FRP linear body 2 is embedded in the rubber 3 and formed into a square cross section. FIG. 2 is a sectional view of the FRP linear body 2 constituting the bead annular body of FIG. As shown in the drawing, the FRP linear body 2 is a wire having a circular cross-sectional shape obtained by impregnating and adhering a thermoplastic resin 5 as a matrix to a cord-like fiber bundle composed of a large number of non-metallic fiber filaments 4 and integrating the same. It is formed into a shape.

The cord-shaped fiber bundle constituting the FRP linear body 2 has a specific gravity of less than 3.0 and a tensile strength of 150 kgf.
/ Mm ² or more and a non-metallic fiber filament 4 having physical properties of a tensile modulus of 4000 kgf / mm ² or more.
If the specific gravity of the non-metallic fiber filaments 4 is 3.0 or more, the merit as a lightweight material is not exhibited, and the tire cannot be sufficiently reduced in weight. In addition, the tensile strength is 150k
If the amount is less than gf / mm ² , unless the amount of the FRP linear body is increased, the required strength as a bead ring cannot be obtained, and the weight cannot be sufficiently reduced. On the other hand, if the tensile modulus is less than 4000 kgf / mm ² , the rigidity of the bead portion of the tire is insufficient and the steering stability is reduced.

The thickness of the cord-like fiber bundle is 20,000
It is preferably 0 denier (D) or less. When the thickness is 20,000 D or less, the resin can be easily impregnated into the inside, the convergence effect of the non-metallic fiber filaments is improved, and the utilization efficiency of the tensile modulus of the cord-like fiber bundle is improved. Resistance to bending strain increases, and steering stability can be improved. The cord-like fiber bundle is usually used without twist, but for imparting convergence, a slight twist can be imparted to the extent that the impregnation of the resin is not impaired.

The non-metallic fiber material constituting such a cord-like fiber bundle of the present invention includes, for example, carbon fiber, aramid fiber (polyparaphenylene terephthalamide fiber),
Glass fiber, polyarylate fiber, silicon carbide fiber, boron fiber and the like can be mentioned. On the other hand, the matrix of the FRP linear body of the present invention has a tensile modulus of 10 kgf.
/ Mm ² or more of the thermoplastic resin 5 is used. If the tensile modulus is less than 10 kgf / mm ² , the rigidity of the FRP is insufficient, and the bead annular body is likely to buckle due to the stress repeatedly applied to the tire during running, so that the durability of the tire decreases. Also, although the vulcanization is performed at a relatively high temperature for a short time in the tire manufacturing process, the bead ring is easily deformed when melted or vulcanized during vulcanization, and the design shape of the tire changes. . For this reason, it is desirable to use a crystalline thermoplastic resin having a melting point of 200 ° C. or higher, and a non-crystalline thermoplastic resin having a glass transition point of 20 ° C. or higher. Such thermoplastic resins include, for example, nylon, polyester, polycarbonate, polyacetal, polyetheretherketone, chlorinated polyether, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylene oxide, polyarylate, polyetherimide, polyamide Imide, polyoxybenzoyl, polyethylene, polypropylene,
Polystyrene, polyvinyl chloride, acrylic resin, fluorine resin and the like can be mentioned.

The amount of the thermoplastic resin 5 impregnated on the cord-like fiber bundle 4 is preferably at least 15% by weight, more preferably at least 30% by weight, based on the weight of the cord-like fiber bundle.
If it is less than 15% by weight, it is insufficient to impregnate uniformly, and the convergence effect on a large number of filaments is reduced.
Since the utilization efficiency of the tensile modulus of the cord-shaped fiber bundle is reduced, the resistance to bending strain is reduced, and the steering stability is reduced.

This FRP linear body has a diameter of 0.7 mm or more.
It should be within the range of 2.0 mm. If the diameter is 0.7 mm or less, the shape stability of the tire in the step before vulcanization is reduced. Further, the rigidity of the bead portion of the tire is insufficient, and steering stability is deteriorated. When the diameter is 2.0 mm or more, the bead rigidity of the tire becomes too large, the rim assemblability deteriorates, and the FR
The change in the cross-sectional area at the end of the P linear body increases, and the uniformity decreases.

The cross-sectional shape of the FRP linear body may be a circle or a triangle having a cross-sectional area equivalent to the circular cross-section having a diameter in the range of 0.7 mm to 2.0 mm to a substantially circular shape. Various cross-sectional shapes such as polygons and other irregular shapes can be used. A plurality of such FRP linear bodies are embedded in rubber so that the volume fraction is in the range of 0.3 to 0.8. By combining and integrating the FRP linear body with rubber as a matrix, it is possible to impart flexibility while satisfying the rigidity required for the bead annular body. However, if the volume fraction of the FRP linear body is less than 0.3, the amount of rubber in the matrix becomes too large, the bead rigidity decreases, and the steering stability of the tire decreases. On the other hand,
If the volume fraction exceeds 0.8, the amount of rubber becomes too small and the flexibility of the bead annular body (bead portion) is reduced, so that the rim assemblability is deteriorated. Leads to. In addition, the adhesiveness between the FRP linear body and the rubber is weakened, and when subjected to repeated impacts such as when traveling on rough roads, separation occurs and the FRP linear body breaks. In addition, even if it does not break, there is a problem that the strength of the FRP linear body is impaired due to wear between the FRP linear bodies.

An adhesive is applied to the FRP linear body to improve the adhesion to rubber. As such an adhesive, there is a so-called mixed liquid (RFL) of a resorcinol-formalin precondensate and latex. In order to further improve the adhesion to rubber, it is preferable to use a chlorinated rubber-based adhesive, or to perform surface treatment by plasma treatment or etching with an acid, and then to perform the RFL treatment.

[0017]

EXAMPLES The following four types of FRP linear bodies a, b, c and d were produced. FRP linear body A: specific gravity 1.8, tensile strength 360 kgf / mm ²
, Tensile modulus of 23,500 kgf / mm ² , thickness 9,0
100D untwisted carbon fiber with tensile modulus of 400 Kgf
A polyetheretherketone resin having a melting point of 334 ° C./mm ² and a melting point of 334 ° C. was melted and impregnated so as to have an adhesion amount of 35% by weight, and then a FRP linear body having a circular cross section was produced through a die.

FRP linear body b: Specific gravity 2.52, tensile strength 2
80 kgf / mm ² , tensile modulus 7,500 kgf / mm
² , FRP on untwisted glass fiber of 10,000D thickness
Melt the same nylon 6 resin as the linear body B
After impregnating and adhering to 5% by weight, a FRP linear body having a circular cross section was produced through a die.

FRP linear body: An FRP linear body was prepared in the same manner as the FRP linear body except that a thermoplastic polyester elastomer having a tensile modulus of 9 kgf / mm ² and a melting point of 213 ° C. was used as the thermoplastic resin. C was prepared. FRP linear body D: An FRP linear body was prepared in the same manner as the FRP linear body B except that the amount of the nylon 6 resin attached was changed to 10% by weight.

An adhesive is applied to each of the above-mentioned FRP linear bodies (a), (b), (c), (d) and the steel wire in order to improve the adhesiveness to rubber, and these are used as bead rings, respectively. Kinds of the present invention tire A, the present invention tire B, and comparative tires A, B, C, D, E, F, and G were produced. The size of these tires is the same 19
5 / 70HR14. Invention tire A: A tire composed of the following bead ring, carcass layer and belt layer.

Bead bead: FRP linear body having a diameter of 1.0 mm is embedded in rubber so that its volume fraction becomes 0.6, and is wound 25 times. Carcass layer: 1000D
Belt layer in which two polyester cords of / 2 are laminated: 1
× 5 × 0.25 steel cords were arranged so as to intersect with each other at 20 ° in the tire circumferential direction at a driving number of 40 per 5 cm. Tire B of the present invention: In the Tire A of the present invention, a FRP linear body having a diameter of 1.2 mm was embedded in rubber so as to have a volume fraction of 0.6 as a bead annular body and wound 25 times. Comparative tire A: In the tire A of the present invention, a FRP linear body having a diameter of 1.2 mm as a bead annular body was embedded in rubber so as to have a volume fraction of 0.2 and 25 times. Comparative tire B: In the tire A of the present invention, a FRP linear body A having a diameter of 1.0 mm was used as a bead ring body without embedding it in rubber (volume fraction: 1.0). Comparative tire C: In the tire A of the present invention, a rubber having a bead annular body and a FRP linear body having a diameter of 1.2 mm and a volume fraction of 0.6 was used. It ’s a 25-turn tire embedded inside. Comparative tire D: In the tire A of the present invention, a FRP linear body having a diameter of 0.9 mm was embedded as a bead annular body in rubber so as to have a volume fraction of 0.6, and wound 25 times. Tire Comparative tire E: In the tire A of the present invention, a FRP linear body 0.5 mm in diameter was embedded as a bead annular body in rubber so that the volume fraction was 0.6, and wound 25 times. Comparative tire F: In the tire A of the present invention, a FRP linear body A having a diameter of 3.0 mm as a bead annular body was embedded in rubber so that the volume fraction thereof was 0.6, and was 25%. Comparative tire G: In the tire A of the present invention, a steel wire having a diameter of 0.95 mm was embedded as a bead ring in rubber so that the volume fraction was 0.4, and 25 times. The wound tire You.

With respect to these nine types of tires, the steering stability test, the tire rolling resistance, the tire weight, the rim assembly, the uniformity, and the strength retention of the composite linear body after running on a rough road were evaluated. The evaluation results of the steering stability test, the rolling resistance of the tire, and the weight of the tire were indicated by indices with the evaluation result of the comparative tire G being 100. The higher the index value, the better these performances.

The strength retention rate after running on a rough road is indicated by an index when the strength at the time of new article is set to 100. The larger the value, the better the strength retention. The methods for evaluating the steering stability test, the tire rolling resistance and the strength retention after running on rough roads are as follows. Driving stability test : In the feeling test of the test driver, points were deducted from the reference tire as 100 points, and superiority was evaluated by adding points. Tire rolling resistance : The tire is rotated on the drum at a peripheral speed of 150 Km / hr, and then the drum is driven along with it to calculate the rolling resistance between the tire and the drum from the relationship between the damping speed of the drum and time, and the rotation of the drum under no load The rolling resistance of the tire was determined by subtracting the resistance. Strength retention after running on rough road : After traveling 20,000 km on a rough road, the composite linear body was taken out of the tire, and the strength was measured with a tensile tester and compared with the strength when new.

Table 1 shows the evaluation results.

[Table 1]

As shown in Table 1, the tires A and B of the present invention
All of the comparative tires A to F are significantly lighter in weight than the comparative tire G using a steel wire, and have improved tire rolling resistance. However, as in Comparative Tire A, a bead-shaped FRP linear body having an extremely low volume fraction (0.2) has insufficient weight reduction and reduced steering stability. Also, when the FRP linear body is not embedded in rubber as in the comparative tire B,
The strength is reduced during driving.

Further, when the tensile elastic modulus (9 kgf / mm ² ) of the thermoplastic resin forming the FRP linear body is small as in the comparative tire C, a decrease in the strength with running is also observed. In the case of the comparative tire D, the amount of the thermoplastic resin impregnated (10% by weight) of the matrix forming the FRP linear body was small, the convergence of the filament was reduced, and the steering stability was greatly reduced.

In the comparative tire E, the wire diameter of the FRP linear body was small (0.5 mm), indicating that the steering stability was reduced. Conversely, when the wire diameter of the FRP linear body is large (3.0 mm) as in the comparative tire F, the rim assemblability is poor and the uniformity is reduced. On the other hand, the tire A of the present invention and the tire B of the present invention are both reduced in weight without impairing the rim assemblability, durability and steering stability.

[0028]

As described above, according to the present invention,
Since a bead annular body was formed from the FRP linear body, and the reinforcing fiber of the FRP linear body was a cord-like fiber bundle made of nonmetallic fiber filaments having a low specific gravity and a specific tensile strength and elastic modulus, In addition, it is possible to impart the strength characteristics and bead portion rigidity required of the bead annular body while significantly reducing the weight of the bead annular body. Further, by impregnating and adhering a specific amount of a thermoplastic resin having a tensile elastic modulus of a certain value or more after curing as a matrix of the FRP linear body, the convergence to the cord fiber bundle is improved, and the buckling resistance against repeated stress is improved. By increasing the size, the durability of the bead ring can be improved.

Further, the FRP linear body has a specific wire diameter,
Since the volume fraction is embedded in the rubber so as to be within a specific range, imparting flexibility while satisfying the rigidity required for the bead annular body, improving the molding stability in the production of the tire, Good rim assemblability can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of a bead ring of the tire of the present invention.

FIG. 2 is a sectional view showing an example of a linear body made of a fiber reinforced resin constituting the bead annular body of FIG. 1;

[Explanation of symbols]

1 Bead annular body 2 FRP linear body
3 Rubber 4 Non-metallic fiber filament
5 thermoplastic resin

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) B60C 15/00-15/04 B60C 1/00 B29D 30/48

Claims (1)

(57) [Claims] 1. Specific gravity of less than 3.0, tensile strength of 150 kgf
/ Mm ² or more, and a cord-like fiber bundle composed of a large number of nonmetallic fiber filaments having a tensile modulus of 4000 kgf / mm ² or more, a tensile modulus of 10 kgf / mm ² as a matrix.
15% by weight or more of the above thermoplastic resin is impregnated and adhered to form a linear body made of a fiber reinforced resin composite material having a wire diameter of 0.7 mm to 2.0 mm, and a plurality of the linear bodies have a volume fraction of 0. .3
A pneumatic tire having a bead ring shape by being embedded in rubber in the range of 0.8 to 0.8.