JP2009214846A - Bias tire for aircraft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bias tire for an aircraft having a carcass protective layer which is capable of largely enhancing the cutting resistance. <P>SOLUTION: The bias tire has at least a pair of bead cores 4 and a bias carcass 5, and a carcass protective layer 6 is provided outwardly in the radial direction of a crown part of the bias carcass 5. The heat shrinkage stress σ of organic fiber cord constituting the carcass protective layer 6 and the modulus E of elasticity satisfy the inequalities σ≥-0.01E+1.2 and σ≥0.02. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aircraft bias tire, and more particularly to an aircraft bias tire excellent in cut resistance.

  Aircraft tires have a very high filling internal pressure exceeding 10 atm. According to official standards, the tires have a pressure resistance four times that of the specified internal pressure in order to meet the requirements for high reliability of tires. is needed.

  In addition, since the aircraft tire bears a large load, the deflection of the tire in use is set to be very large. That is, since the amount of deformation of the bias carcass of the tire during traveling is large, it is essential to employ a material and structure that can withstand the deformation that is repeated every time the bias carcass travels.

  In order to meet these demands and prevent the intrusion of foreign matter into the tread part while filling the tire with a high internal pressure, conventionally, it consists of a high-strength nylon cord radially outward of the crown part of the bias carcass. A carcass protective layer has been provided to improve durability.

  However, in such a tire for an aircraft, under a high-temperature condition due to high-speed running, the tread portion protrudes radially outward due to the action of centrifugal force during high-speed rotation. Because the tire is stretched in the circumferential direction of the tire, especially when taking off and landing, when the tire passes over a dull or sharp foreign object such as a stone or metal piece on the runway, the resistance of the tread to the foreign object The force was weakened, and the tread rubber could be cut by the foreign matter that was stepped on.

  Accordingly, an object of the present invention is to provide an aircraft bias tire having greatly improved cut resistance, particularly in a tire having a carcass protective layer.

An aircraft bias tire according to the present invention includes at least a pair of bead cores and a toroidal shape extending between the bead cores, and two or more carcass plies formed of a rubber coating layer of a plurality of organic fiber cords. A bias carcass formed by laminating at an interlayer crossing posture, and having a carcass protective layer radially outward of the crown portion of the bias carcass, wherein the heat shrinkage stress of the organic fiber cord constituting the carcass protective layer σ and elastic modulus E are the following formulas (1) and (2):
σ ≧ −0.01E + 1.2 (1)
σ ≧ 0.02 (2)
[In the formula, σ is a heat shrinkage stress (cN / dtex) at 177 ° C., and E is an elastic modulus (cN / dtex) at a load of 49 N at 25 ° C. ]
It satisfies the relationship.

Here, the heat shrinkage stress σ is a 25 cm length sample of an organic fiber cord before vulcanization subjected to a general dip treatment and subjected to a general dip treatment according to a test of JIS L1017 8.10. And stress (cN / dtex) generated in the cord when heated at 177 ° C. for 2 minutes.
The elastic modulus E means an elastic modulus (cN / dtex) calculated from a tangent line at 49N of the SS curve according to a cord tension test of JIS L1017 8.5.
In the aircraft bias tire of the present invention, as the gas filled in the tire, normal air, air with a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

  In such a tire, more preferably, the heat shrinkage stress σ of the organic fiber cord constituting the carcass protective layer is 0.1 to 1.5 cN / dtex, and the organic fiber cord constituting the carcass protective layer is a polyketone fiber cord. And

  By the way, the polyketone is preferably a copolymer of carbon monoxide and at least one kind of unsaturated hydrocarbon, and more preferably, the unsaturated hydrocarbon is ethylene.

  Preferably, the arrangement density of the organic fiber cords constituting the carcass protective layer is 3.0 to 10.0 pieces / 10 mm in the tire width direction.

  In conventional aircraft tires, the high-pressure and centrifugal force during high-speed rotation causes the tread portion to protrude radially outward due to high internal pressure and high-speed rotation. Due to the stretching in the tire circumferential direction, the cut resistance may be reduced.

In contrast, in the aircraft bias tire of the present invention, in particular, the heat shrinkage stress σ and the elastic modulus E of the organic fiber cord constituting the carcass protective layer are expressed by the following formulas (1) and (2):
σ ≧ −0.01E + 1.2 (1)
σ ≧ 0.02 (2)
[In the formula, σ is a heat shrinkage stress (cN / dtex) at 177 ° C., and E is an elastic modulus (cN / dtex) at a load of 49 N at 25 ° C. ]
The organic fiber cords that make up the carcass protective layer are heat-shrinked by heat generated during high-speed driving to ensure the exertion of large heat-shrinking stress. The occurrence of cuts due to the increase in the tread circumference by restraining the tire's diameter expansion deformation by strongly restraining the tread portion from protruding radially outward due to the centrifugal force Can be effectively prevented.

  That is, in the case of σ <−0.01E + 1.2 and in the case of σ <0.02, the effect of preventing the tread portion from protruding outward in the radial direction during high speed running is insufficient, and Improve cutting performance.

Hereinafter, embodiments of an aircraft bias tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction showing one embodiment of an aircraft bias tire of the present invention in a filling posture of a prescribed internal pressure.
In the figure, 1 is a tread portion, 2 is a pair of sidewall portions extending radially inward continuously to the side portions of the tread portion, and 3 is a bead provided continuously on the inner peripheral side of each sidewall portion 2. Each part is shown.

  In the tire shown here, three pairs of bead cores 4 embedded in a pair of bead portions 3, between these bead cores 4, extend in a toroid shape, and the bias carcass 5 is connected to, for example, the tire equatorial plane. Two carcass plies made of a plurality of organic fiber cord coating layers are laminated in an interlayer crossing posture and inclined at an angle in the range of 40 to 70 °.

Further, a carcass protective layer 6 made of an organic fiber cord and a tread rubber 7 are sequentially disposed on the outer side of the crown portion of the bias carcass 5 in the radial direction, and the surface of the tread rubber 7 extends, for example, in the tire circumferential direction. Four circumferential grooves are formed.
Here, in the carcass protective layer 6, for example, the arrangement density of the organic fiber cord in the tire width direction can be set to 3.0 to 10.0 pieces / 10 mm.

  An impermeable inner liner rubber 8 having a barrier property against an enclosed gas such as air is disposed inside the bias carcass 5 in the radial direction.

  FIG. 2A is a partially developed plan view showing a case where the two carcass protective layers of the tire of FIG. 1 are formed by corrugated organic fiber cords, and FIG. FIG. 3 is a partially developed plan view showing a case where two carcass protective layers are formed of angled cords made of organic fibers.

The carcass protective layer 6 shown in FIG. 2A can be formed by winding a large number of organic fiber cords attached to a corrugated shape in the circumferential direction, and even if a high tire internal pressure is filled, the carcass protective layer 6 can be formed. The tension load of the organic fiber cord itself constituting the protective layer 6 can be sufficiently reduced.
Moreover, as shown in FIG.2 (b), the code | cord | chord of many organic fibers is made to extend | stretch linearly at an angle of 50-70 degrees, for example with respect to a tire equator surface, and can infiltrate a foreign material. On the other hand, an excellent protection function against piercing can be exhibited under the inherent rigidity of the organic fiber cord.
In this case, by arranging a plurality of carcass protective layers 6 so that the organic fiber cords constituting the carcass protective layer 6 cross each other, the entry of small foreign matters can be more effectively prevented.

In this aircraft bias tire, the thermal shrinkage stress σ and the elastic modulus E of the organic fiber cord constituting the carcass protective layer 6 are expressed by the following formulas (1) and (2):
σ ≧ −0.01E + 1.2 (1)
σ ≧ 0.02 (2)
[In the formula, σ is a heat shrinkage stress (cN / dtex) at 177 ° C., and E is an elastic modulus (cN / dtex) at a load of 49 N at 25 ° C. ]
Satisfy the relationship.

Here, the elastic modulus E is preferably 60 cN / dtex or more, more preferably 100 cN / dtex or more.
When the elastic modulus E is less than 60 cN / dtex, the effect of suppressing the outward protrusion in the radial direction when traveling at high speed tends to be insufficient.

  In addition, in order to make the effects of the organic fiber cord during normal running and high-speed running compatible, the difference between the heat shrinkage stress of the cord at 20 ° C. and the heat shrinkage stress at 177 ° C. is preferably 0. 20 cN / dtex or more, more preferably 0.25 cN / dtex or more.

  The heat shrinkage stress σ and the elastic modulus E in the formulas (1) and (2) vary depending on the type of the organic fiber cord, but the heat shrinkage stress σ and the elastic modulus can be changed by changing the number of twists and dip treatment conditions at the time of cord preparation. The value of E can be changed.

  In such a heavy duty pneumatic tire, the organic fiber cord constituting the carcass protective layer 6 preferably has a maximum heat shrinkage stress σ of 0.1 to 1.5 cN / dtex, more preferably 0.4 to 1. The range is 0 cN / dtex.

  If it is less than 0.1 cN / dtex, the alignment efficiency due to heating during tire production is lowered, and the strength as a tire tends to be insufficient. On the other hand, when it exceeds 1.5 cN / dtex, the organic fiber cord contracts due to heating at the time of manufacturing the tire, so that the shape of the tire after vulcanization tends to deteriorate.

  More preferably, the organic fiber cord constituting the carcass protective layer 6 is a polyketone fiber cord.

  By using polyketone fiber cords, heat shrinks as the temperature rises, exerts large heat shrinkage stress and elastic force, and has reversibility that stretches and deforms as the temperature falls, resulting in cord fatigue during running The carcass ply can be prevented from breaking, and excellent tire durability can be secured.

ポリケトンは、一酸化炭素ＣＯと不飽和炭化水素との共重合体であり、例えば、高分子鎖中で各ＣＯ単位の隣に、エチレン単位等が一つずつ位置する交互共重合体である。また、ポリケトンは、一酸化炭素と特定の不飽和炭化水素の一種との共重合体であってもよく、一酸化炭素と不飽和炭化水素の二種以上との共重合体であってもよい。式中のＡを形成する不飽和炭化水素としては、エチレン、プロピレン、ブテン、ペンテン、シクロペンテン、ヘキセン、シクロヘキセン、ヘプテン、オクテン、ノネン、デセン、ドデセン、スチレン、アセチレン、アレン等の不飽和炭化水素化合物や、メチルアクリレート、メチルメタクリレート、ビニルアセテート、アクリルアミド、ヒドロキシエチルメタクリレート、ウンデセン酸、ウンデセノール、６−クロロヘキセン、Ｎ−ビニルピロリドン、スルニルホスホン酸のジエチルエステル、スチレンスルホン酸ナトリウム、アリルスルホン酸ナトリウム、ビニルピロリドン及び塩化ビニル等の不飽和結合を含む化合物等であってもよい。これらは単独で用いてもよく、二種以上を組み合わせて用いてもよい。
特にポリマーの力学特性や耐熱性等の点から、不飽和炭化水素としてエチレンを主体とするものを用いたポリケトンが好ましい。 When the organic fiber cord constituting the carcass protective layer 6 is a polyketone fiber cord, it is made of a polyketone fiber substantially composed of a repeating unit represented by Chemical Formula 1.

The polyketone is a copolymer of carbon monoxide CO and unsaturated hydrocarbon. For example, the polyketone is an alternating copolymer in which one ethylene unit is located next to each CO unit in the polymer chain. Further, the polyketone may be a copolymer of carbon monoxide and one kind of specific unsaturated hydrocarbon, or may be a copolymer of two or more kinds of carbon monoxide and unsaturated hydrocarbon. . The unsaturated hydrocarbon forming A in the formula includes unsaturated hydrocarbon compounds such as ethylene, propylene, butene, pentene, cyclopentene, hexene, cyclohexene, heptene, octene, nonene, decene, dodecene, styrene, acetylene, and allene. And methyl acrylate, methyl methacrylate, vinyl acetate, acrylamide, hydroxyethyl methacrylate, undecenoic acid, undecenol, 6-chlorohexene, N-vinylpyrrolidone, diethyl ester of sulphonylphosphonic acid, sodium styrenesulfonate, sodium allylsulfonate, It may be a compound containing an unsaturated bond such as vinyl pyrrolidone and vinyl chloride. These may be used alone or in combination of two or more.
In particular, from the viewpoint of the mechanical properties and heat resistance of the polymer, polyketone using unsaturated hydrocarbons mainly composed of ethylene is preferable.

  The polyketone used as the raw material for the polyketone fiber cord may have partially bonded ketone groups and unsaturated hydrocarbon-derived portions, but the unsaturated hydrocarbon-derived portions and ketone groups are alternately arranged. It is preferable that the proportion of the portion is 97% by mass or more.

（式中、ｔ及びＴは、純度９８％以上のヘキサフルオロイソプロパノール及びヘキサフルオロイソプロパノールに溶解したポリケトンの希釈溶液の２５℃での粘度管の流過時間であり；Ｃは、上記希釈溶液１００ｍＬ中の溶質の質量（ｇ）である）で定義される極限粘度［η］が１〜２０ｄＬ／ｇの範囲にあることが好ましく、２〜１０ｄＬ／ｇの範囲にあることが更に好ましく、３〜８の範囲にあることがより一層好ましい。極限粘度が１ｄＬ／ｇ未満では、分子量が小さ過ぎて、高強度のポリケトン繊維コードを得ることが難しくなる上、紡糸時、乾燥時及び延伸時に毛羽や糸切れ等の工程上のトラブルが多発することがあり、一方、極限粘度が２０ｄＬ／ｇを超えると、ポリマーの合成に時間及びコストがかかる上、ポリマーを均一に溶解させることが難しくなり、紡糸性及び物性に悪影響が出ることがある。 Furthermore, as the polymerization degree of the polyketone, the following formula:

(In the formula, t and T are hexafluoroisopropanol having a purity of 98% or more and a polyketone diluted solution dissolved in hexafluoroisopropanol at a flow rate of 25 ° C. in a viscosity tube; C is in 100 mL of the diluted solution) The intrinsic viscosity [η] defined by the mass (g) of the solute is preferably in the range of 1 to 20 dL / g, more preferably in the range of 2 to 10 dL / g, and 3 to 8 It is still more preferable that it exists in the range. If the intrinsic viscosity is less than 1 dL / g, the molecular weight is too small to obtain a high-strength polyketone fiber cord, and troubles such as fluff and yarn breakage occur frequently during spinning, drying and stretching. On the other hand, if the intrinsic viscosity exceeds 20 dL / g, it takes time and cost to synthesize the polymer, and it becomes difficult to uniformly dissolve the polymer, which may adversely affect the spinnability and physical properties.

  Here, as a spinning method of the unstretched yarn of polyketone, a known method can be employed, and specifically, JP-A-2-112413, JP-A-4-228613, and JP-T-4-505344. A wet spinning method using an organic solvent such as hexafluoroisopropanol and m-cresol, as described in WO 99/18143, WO 00/09611, JP 2001-164422, JP 2004-218189. And a wet spinning method using an aqueous solution of zinc salt, calcium salt, thiocyanate, iron salt and the like as described in JP-A No. 2004-285221.

  For example, in a wet spinning method using an organic solvent, a polyketone polymer is dissolved in hexafluoroisopropanol, m-cresol, or the like at a concentration of 0.25 to 20% by mass, extruded from a spinning nozzle to be fiberized, and then toluene, ethanol, isopropanol The unstretched yarn of polyketone can be obtained by removing and washing the solvent in a non-solvent bath such as n-hexane, isooctane, acetone or methyl ethyl ketone.

  On the other hand, in the wet spinning method using an aqueous solution, for example, a polyketone polymer is dissolved in an aqueous solution of zinc salt, calcium salt, thiocyanate, iron salt or the like at a concentration of 2 to 30% by mass, and a spinning nozzle is formed at 50 to 130 ° C. Then, it is extruded into a coagulation bath and subjected to gel spinning, followed by desalting and drying to obtain an undrawn polyketone yarn.

  Further, for example, according to the method described in JP-A-2-112413, the polymer is dissolved in, for example, hexafluoroisopropanol, m-cresol, etc. at a concentration of 0.25 to 20% by mass, preferably 0.5 to 10% by mass. The fiber is extruded from a spinning nozzle, and then the solvent is removed and washed in a non-solvent bath such as toluene, ethanol, isopropanol, n-hexane, isooctane, acetone, methyl ethyl ketone, preferably an acetone bath to obtain a spinning yarn. Further, a solution spinning method in which stretching treatment is performed at a temperature in the range of (melting point−100 ° C.) to (melting point + 10 ° C.), preferably (melting point−50 ° C.) to (melting point) can be employed.

  The unstretched yarn of the resulting polyketone can be obtained by (i) performing multi-stage hot drawing and drawing at a specific temperature and magnification in the final drawing step of the multi-stage hot drawing, or (ii) after hot drawing and completion of hot drawing. A method of rapid cooling while applying high tension to the fibers is preferred. A desired filament suitable for production of a polyketone fiber cord can be obtained by fiberizing the polyketone by the method (i) or (ii).

  As a drawing method of the obtained undrawn yarn, a hot drawing method in which the undrawn yarn is heated and drawn to a temperature higher than the glass transition temperature of the undrawn yarn is preferable. ) May be carried out in one stage, but it is preferably carried out in multiple stages. There is no restriction | limiting in particular as a method of heat drawing, For example, the method etc. which run a thread | yarn on a heating roll or a heating plate are employable. Here, the heat stretching temperature is preferably in the range of 110 ° C. to (the melting point of the polyketone), and the total stretching ratio is preferably 10 times or more.

  When polyketone fiberization is carried out by the method (i) above, the temperature in the final stretching step of the multistage thermal stretching is preferably in the range of 110 ° C. to (the stretching temperature of the stretching step one step before the final stretching step). Moreover, the draw ratio in the final drawing step of multistage heat drawing is preferably in the range of 1.01 to 1.5 times. On the other hand, when polyketone fiberization is carried out by the method (ii) above, the tension applied to the fiber after completion of the hot drawing is preferably in the range of 0.5 to 4 cN / dtex, and the cooling rate in rapid cooling is 30 The cooling end temperature in the rapid cooling is preferably 50 ° C. or less. Here, there is no restriction | limiting in particular as a rapid cooling method of the heat-stretched polyketone fiber, A conventionally well-known method can be employ | adopted, Specifically, the cooling method using a roll is preferable. In addition, since the polyketone fiber obtained in this way has a large residual elastic strain, it is usually preferable to perform relaxation heat treatment so that the fiber length is shorter than the fiber length after hot drawing. Here, the temperature of the relaxation heat treatment is preferably in the range of 50 to 100 ° C., and the relaxation ratio is preferably in the range of 0.980 to 0.999 times.

  The organic fiber cord is formed by, for example, twisting a plurality of filament bundles made of polyketone, preferably two or three strands. Thus, by twisting in the opposite direction, a twisted cord having a double twist structure can be obtained.

By the way, by setting the arrangement density of the organic fiber cords constituting the carcass protective layer 6 to 3.0 to 10.0 pieces / 10 mm in the tire width direction, the durability against the intrusion of foreign matter into the tread portion 1 is further improved. Can be increased.
That is, when the arrangement density is less than 3.0 / 10 mm, the space between the cords of the organic fiber cords becomes wide, so that it is difficult to protect small foreign matters, while 10.0 / 10 mm is used. In the case of exceeding, the rubber gauge between the cords cannot be sufficiently secured due to the denseness of the organic fiber cords, and the adhesiveness of the portion tends to be lowered.

Next, a bias tire having a structure as shown in FIG. 1 and FIG. 2 (b) and having a size of H49 × 19.0-22 32PR was prototyped, and various specifications were changed as shown in Table 1. The cut resistance was evaluated for each of the Example tires and Comparative Example tires 1 to 3.
The polyketone, which is a material used for the organic fiber cord of the carcass protective layer, is almost 100% composed of repeating units represented by the above (Chemical Formula 1), and 97 mol% or more thereof is 1-oxotrimethylene.

For each of the example tires and comparative tires 1 to 3, the tire was mounted on a rim having a rim size of H49 × 19.0-22, the load was 25670 kg (56600 LBS), the internal pressure was 1410 kPa (205 psi), and the diameter was 3048 mm (120 inches). When the speed of the drum testing machine of) reached 380 km / h, a metal plate having a blade having a height of 10 mm and a width of 500 mm was applied to the tire tread, and the cut depth formed on the tire tread was evaluated. The evaluation results are shown in Table 2 as indices.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 1 as control, and shows that performance is so favorable that an index | exponent is large.

  From the results in Table 2, the example tires showed excellent cut resistance with respect to the comparative example tires 1 to 3.

1 is a cross-sectional view in the width direction showing an embodiment of an aircraft bias tire of the present invention in a filling posture of a prescribed internal pressure. (A) is a development top view which shows the aspect which consists of an organic fiber code | cord | chord which the two-layer carcass protective layer of the tire of FIG. 1 was wrinkled, and (b) is two layers of the tire of FIG. It is an expansion | deployment top view which shows the aspect by which the carcass protective layer of this was arrange | positioned with the angle of the organic fiber cord.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Bias carcass 6 Carcass protective layer 7 Tread rubber 8 Inner liner rubber

Claims (6)

A bias formed by laminating at least a pair of bead cores and two or more carcass plies formed of a rubber coating layer of a plurality of organic fiber cords in an interlayer crossing posture between organic fiber cords. In an aircraft bias tire comprising a carcass and having a carcass protective layer radially outward of a crown portion of the bias carcass,
The thermal contraction stress σ and the elastic modulus E of the organic fiber cord constituting the carcass protective layer are expressed by the following formulas (1) and (2):
σ ≧ −0.01E + 1.2 (1)
σ ≧ 0.02 (2)
[In the formula, σ is a heat shrinkage stress (cN / dtex) at 177 ° C., and E is an elastic modulus (cN / dtex) at a load of 49 N at 25 ° C. ]
An aircraft bias tire characterized by satisfying the above relationship.   2. The aircraft bias tire according to claim 1, wherein the heat shrinkage stress σ of the organic fiber cord constituting the carcass protective layer is 0.1 to 1.5 cN / dtex.   The aircraft bias tire according to claim 1 or 2, wherein the organic fiber cord constituting the carcass protective layer comprises a polyketone fiber cord.   The aircraft bias tire according to claim 3, wherein the polyketone is a copolymer of carbon monoxide and at least one unsaturated hydrocarbon.   The aircraft bias tire according to claim 4, wherein the unsaturated hydrocarbon is ethylene.   The aircraft bias tire according to claim 1, wherein an arrangement density of the organic fiber cord constituting the carcass protective layer is 3.0 to 10.0 pieces / 10 mm in the tire width direction.

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