KR20050041007A - High performance radial tire using polyvinylalcohol dip cord - Google Patents

Abstract

A radial pneumatic tire having a flatness ratio of 0.7 or less, comprising: a pair of parallel bead cords and at least one radial carcass ply wound around the bead core and a belt layer laminated on the outer periphery of the carcass; A circumferential belt reinforcement layer formed on the outer circumferential side of the carcass ply includes a deep cord made of polyvinyl alcohol multifilament, and the polyvinyl alcohol deep cord is twisted with high tensile strength during continuous shooting to minimize the strong deterioration. Radiation, characterized by excellent fatigue resistance, adhesion and strength as a high-strength polyvinyl alcohol dip cord that not only prevents penetration into the raw cord of RFL liquid when immersed in the dipping liquid, but also gives high relaxation during heat treatment. It is about a pneumatic tire.

Description

High performance radial tire using Polyvinylalcohol dip cord}

In recent years, the performance of tires has been continuously improved according to the improvement of the road environment and the performance of the vehicle, and in particular, it is recognized that safety is more important as the quality of the tire as the weight of the vehicle increases and the limit speed increases. In line with the demand for increasing tire safety, tire safety standards are also changing, and the tire industry is actively researching methods for providing tire safety.

The present invention relates to a high-performance radial tire manufactured by using a high strength polyvinyl alcohol deep cord having excellent fatigue resistance for a carcass layer and a method of manufacturing the same. More specifically, in a radial pneumatic tire having a flatness ratio of 0.7 or less, a pair of parallel bead cords and at least one radial carcass ply wound around the bead core and a belt layer laminated on the outer circumference of the carcass. And a belt reinforcement layer in a circumferential direction formed on an outer circumferential side of the belt layer, wherein the carcass ply includes a deep cord made of polyvinyl alcohol multifilament, and the polyvinyl alcohol deep cord is twisted with high tensile strength during the twisting. It minimizes the strong deterioration and prevents the penetration of the RFL liquid into the raw cord when immersed in the dipping liquid, and also provides high relaxation during heat treatment, thereby producing a high-strength polyvinyl alcohol deep cord. The present invention relates to a radial pneumatic tire.

Conventional radial tires consist of a carcass ply reinforced with rubber with fiber cords such as polyethylene terephthalate or rayon, and a belt structure reinforced with rubber with steel cords. In addition, the bead wire is reinforced in the contact portion between the tire and the rim to prevent the tire from falling off the rim and to maintain stability, which also serves to fix the carcass ply.

In the first pneumatic tires, cotton canvas was used as a carcass material. With the development of artificial fibers, fiber cords such as rayon, nylon, and polyethylene terephthalate have been used as carcass plies. Cords are used.

In general, polyethylene terephthalate is commonly used as a carcass ply material of pneumatic radial tires, and more specifically, pneumatic radial tires having a flat ratio of 0.65 to 0.82. Background Art Rayon is relatively used as a carcass ply reinforcement for pneumatic radial tires. Although polyethylene terephthalate is used in some of these high-speed, low-flat ratio radial tires, its strength is superior to that of rayon, but its adhesion to rubber is low, and its high temperature properties and shape stability are limited.

Recently, some of the polyethylene naphthalate fibers, which have higher temperature properties and form stability than polyethylene terephthalate, are used to compensate for these problems. However, they are superior in strength to rayon but are limited in their application due to their low adhesion to rubber. .

In the case of general rayon, adhesion with rubber is superior to polyester-based fiber, but in terms of physical properties, the strength is low, and there is a disadvantage that tire weight increases when applied to a tire as well as an unsuitable surface as a tire cord.

Accordingly, the present invention has been made to solve the above problems by applying a polyvinyl alcohol deep cord to the carcass layer of the radial tire to improve the adhesive strength with rubber, which is a disadvantage of polyethylene naphthalate fiber, Its purpose is to provide high performance radial tires by improving its strength.

In order to achieve the above object, the present invention provides a polyvinyl alcohol deep cord for carcass for a car tire through the following processes.

As a preliminary step for producing a polyvinyl alcohol deep cord in the present invention, the production of polyvinyl alcohol multifilament is prepared using the following process.

Hereinafter, the manufacturing process of the polyvinyl alcohol multifilament will be described step by step.

The polyvinyl alcohol fibers used in the present invention may be prepared by (1) dissolving polyvinyl alcohol in a degree of polymerization of 1,500 to 7,000 and a saponification degree of 99.9 mol% or more in dimethyl sulfoxide (hereinafter referred to as 'DMSO'). Spinning step; (2) stretching step of stretching the polyvinyl alcohol unstretched yarn thus prepared at a high magnification of 15 times or more and then heat-treating; (3) twisting step of giving a twist to secure the strength and fatigue resistance required when using a tire cord; (4) It is made by a manufacturing process including a dipping step of impregnating and heat-treating the RFL (Resorcinol formaline latex) resin in order to increase the adhesiveness and rubber to the prepared PVA raw cord.

In the present invention, polyvinyl alcohol polymerization degree is about 1,500 to 7,000 is used, preferably high polymerization polyvinyl alcohol of 1,700 to 3,000 is effective. Spinning may be wet, dry, or wet, but in particular, it is possible to manufacture a polyvinyl alcohol fiber having a uniform structure in a wet and dry spinning method, and thus it is possible to produce a fiber having excellent fatigue resistance.

Figure 1 is an example showing the wet-and-dry spinning process of the polyvinyl alcohol fiber according to the present invention, when the polyvinyl alcohol solution is quantitatively supplied from the gear pump (1) in Figure 1, through the spinning nozzle (2) The discharged spinning stock solution passes through the air layer 3 in the vertical direction and reaches the coagulation liquid interface. The spinning nozzle 2 used is usually circular in shape.

Considering the tire cord and the industrial in terms of use, in consideration of the nozzle interval for uniform cooling of the solution, the number of nozzles is 200 to 1,500.

When the fibrous spinning stock solution passed through the spinning nozzle 2 is solidified in the upper coagulating solution, the larger the diameter of the fluid, the greater the difference in the coagulation rate between the surface and the inside, thus making it difficult to obtain a uniform gel structure. A roller 6 for converting the multifilament introduced into the coagulation bath in the horizontal direction in the horizontal direction is provided. The roller 6 is rotated to reduce the frictional resistance. The coagulated fiber in the coagulation bath removes 100% of the spinning solvent in an extraction tank composed of methanol, and dried and attaches oil to the surface to prepare polyvinyl alcohol unstretched fiber.

The polyvinyl alcohol stretching process of the present invention should be carried out 15 times or more at 170 to 250 ℃, the stretching workability is bad at 170 ℃ or less and pyrolysis occurs at 250 ℃ or more, so 200 to 230 ℃ is preferred for the production of high strength fibers. . Next, a polyvinyl alcohol fiber is twisted according to the use to prepare a raw cord. For example, the tire cord used for the radial tire carcass part is used to give 1500 d / 2p of 300-450 TPM and give the number of years of lower and upper edges.

In the twisting process of the present invention, it is preferable to perform the low-strength and the high-strength twisting force at 0.08 to 0.20 g / d, which is good at twisting workability at 0.08 g / d or less, but strongly deteriorates, and at least 0.20 g / d. This is because damage occurs and workability is reduced. More preferably, the yarn is twisted at a tension of 0.10 to 0.15 g / d. In this case, the raw cord can be manufactured with high strength and high modulus of elasticity.

In order to improve the adhesiveness with the rubber to the raw cord prepared as described above, the RFL solution is attached and dried and heat treated.

In more detail, the dipping process of the present invention, dipping is achieved by impregnating the surface of the fiber with a resin layer called RFL (Resorcinol-Formaline-Latex), which is inferior to the original rubber, It is to improve the disadvantages.

In the present invention, it can be prepared using the following method as an example of the adhesive liquid for the adhesion of the polyvinyl alcohol raw cord and rubber. The examples described below are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

29.4 wt% Resorcinol 45.6

Pure 255.5

37% formalin 20

10wt% sodium hydroxide 3.8

After preparing the solution, the reaction was stirred at 25 ° C. for 5 hours, and then the following components were added.

40wt% VP-Latex 300

Pure 129

28% ammonia water 23.8

After the ingredient is added, the mixture is aged at 25 ° C. for 20 hours to maintain a solid concentration of 19.05%.

In order to prevent the RFL solution from penetrating deeply to the inside when applying the RFL, a stretch of 0.5 to 3% is given when the RFL solution is attached, and the RFL solution adhesion rate (hereinafter referred to as DPU) is set to 4.0 to 9.0 wt%. This is because at 0.5% or less stretch, the DPU becomes excessively more than 9wt% and penetrates deep into the short fiber to reduce fatigue resistance, and at 3% or more, excessive tension is applied to the raw cord, which causes damage to the raw cord. The heat treatment should be carried out at 170 to 230 ° C., particularly 200 to 220 ° C. where the polyvinyl alcohol molecular motion of the amorphous portion is the best. At this time, by minimizing the tension imparted to the fiber to maximize the heat treatment effect by maximizing the molecular movement it becomes possible to manufacture a high strength deep cord.

In the present invention, it is important to set the stretch ratio to 0 to -5% in the heat treatment step after immersing the raw cord in the dipping liquid. If the stretch is more than 0% in heat treatment, since the deep cord elongation is low, when the tire cord is used for a tire cord requiring high fatigue resistance with less than 60% fatigue resistance, cord breakage or breakage occurs. On the other hand, in the case of -5% or less, recrystallization occurs in a direction perpendicular to the fiber axis due to excessive molecular movement, causing strong degradation.

The polyvinyl alcohol dip cord prepared according to the above-described method has an adhesive force of 10 kg or more, preferably 12 to 50 kg, total denier of 1000 to 6000 days, and a cutting load of 10.0 to 65.0 kg. It can be advantageously used as a tire cord.

In the present invention by using the prepared deep cord as a carcass, a tire for a passenger car is manufactured.

Figure 2 schematically shows the structure of a tire for a passenger car manufactured using the polyvinyl alcohol dip cord according to the present invention. 2 will be described in more detail as follows.

The bead regions 35 of the tire 31 each have an annular bead core 36 that is inextensible. Beadcores are preferably made from single or multiple filament steel wires wound in series. In a preferred embodiment, high strength steel wires of 0.95 mm-1.00 mm diameter form a 4x4 structure, and it is also possible to form a 4x5 structure.

In a particular embodiment of the invention, the bead region also has a bead filler 37, in the case of the bead filler, it is necessary to have a hardness of at least a certain level, preferably Shore A hardness of 40 or more is preferred.

In the present invention, the tire 31 is reinforced by the crown portion by the belt 38 and the cap fly 39 structure. The belt structure 38 includes two cutting belt plies 40 and the cords 41 of the belt plies are oriented at an angle of about 20 degrees with respect to the circumferential central surface of the tire. The cord ply 41 of the belt ply is arranged opposite to the direction of the cord 22 of the other belt ply in a direction opposite the circumferential central plane. However, the belt 38 may comprise any number of plies and may preferably be arranged in the range of 16-24 °. The belt 38 serves to provide lateral stiffness to minimize the rise of the tread 43 from the road surface during operation of the tire 31. The cords 41 and 42 of the belt 38 are made of steel cords and have a 2 + 2 structure, but can be manufactured in any structure. The cap ply 41 and the edge ply 44 are reinforced on the upper portion of the belt 38. The cap ply cord 45 in the cap ply 39 is reinforced in parallel to the circumferential direction of the tire, thereby increasing the speed of the tire. It serves to suppress the change in the size of the circumferential direction, and a cap fly cord 45 having a large heat shrinkage stress at a high temperature is used. The cap fly cord uses a dip cord made of polyvinyl alcohol multifilament prepared according to the method of the present invention. One layer of cap ply 39 and one layer of edge ply 41 may be used, but preferably 1-2 layers of cap ply and also 1-2 layers of ply reinforcement.

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention. In Examples and Comparative Examples, properties of the tire cord and the like were evaluated in the following manner.

(a) Deep Code Strength (kgf, Strength)

After drying at 107 ° C. for 2 hours, an Instron low speed tensile tester was used. After twisting 80 TPM (twist per meter), the sample was measured at 250 mm and a tensile rate of 300 m / min.

(b) Dry heat shrinkage (%, Shrinkage)

After drying for 24 hours at 25 ° C. and 65% RH, dry heat shrinkage was determined using the ratio of the length (L ₀ ) measured in 20 g stop and the length (L ₁ ) after treatment at 20 g static load for 30 minutes at 150 ° C. Indicates.

S (%) = (L ₀ -L ₁ ) / L ₀ × 100

(c) even with fatigue

The fatigue strength of the tire cord was measured by using the Goodrich Disc Factigue Tester which is commonly used for fatigue testing of tire cords. The fatigue test conditions were 120 ° C., 2500 RPM, and a compression of 18%. After the fatigue test, the rubber was swelled by immersion in tetrachloroethylene solution for 24 hours, and the rubber and cord were separated to measure residual strength. The residual strength was measured according to the method (a) using a conventional tensile strength tester after drying for 2 hours at 107 degrees.

(d) adhesion

H-test was performed to measure the initial adhesion of the deep cord to the rubber. H-test measures the maximum load that the rubber-cord separation occurs by pulling both rubbers while keeping both ends of the deep cord embedded in 9.5mm rubber lumps and keeping the distance between the rubber lumps at both ends 9mm. It is a method of evaluating adhesive force. In addition, sufficient strength is given to a rubber | gum by measuring at 20 degreeC and the pressure of 25 kg / cm <^2> for 20 minutes, before adhesive force evaluation. The rubber composition used in the test was 100 parts of natural rubber, 3 parts of zinc oxide, 28.9 parts of carbon black, 2 parts of stearic acid, 7.0 parts of pintar, 1.25 parts of MBTS, 3 parts of sulfur, 0.15 parts of diphenyl guanidine and phenylbeta naphthylamine 1.0 part is mix | blended.

       (e) Deep Code Strong Utilization (%)

Deep cord potency was measured by the following equation.

% Strength utilization = {deep code strength (kg) / 2 × yarn strength (kg)} × 100%

Example 1

Polyvinyl alcohol with an average degree of polymerization of 2,500 and saponification degree of 99.9 mol% was dissolved in DMSO, an organic solvent, to prepare a spinning solution with a uniform structure, and dry-spun in a coagulation bath at a DMSO / methanol ratio of 3/7 by weight and 10 ° C. . Next, while performing wet drawing in an extraction tank, DMSO is removed by methanol as an extraction solvent, followed by drying and adding an emulsion to prepare unstretched fibers. Such undrawn yarn is drawn at 230 ° C. to have a total draw ratio of 19 times, and heat treated at 240 ° C. to produce polyvinyl alcohol fibers. The fiber obtained has a high strength of 15 g / d at a fineness of 1500 d / 500 f.

Next, polyvinyl alcohol fibers were rolled using a ring yarn at 36.0 TPM soft water and a tension of 0.12 g / d, and then the two low twist yarns were combined to perform a stage at 0.15 g / d. The deep cord was prepared by immersing the raw cord in RFL solution and then performing heat treatment under a stretch of -3%. Table 1 shows the physical properties of the dip cord thus prepared.

Example 2

The polyvinyl alcohol fiber was subjected to low-yeon in soft water 36.0TPM and tension of 0.15g / d by using a ring yarn, and then two low-twisted yarns were combined and performed at 0.17g / d, and the raw cord was heat-treated under -2% stretch. Except that the tip cord was prepared in the same manner as in Example 1. Table 1 shows the physical properties of the dip cord thus prepared.

Example 3

The polyvinyl alcohol fiber was subjected to low-yeon in soft water 36.0 TPM and tension 0.10 g / d using a ring yarn, and then two low-twisted yarns were combined and superimposed at 0.12 g / d, and the raw cord was heat-treated under -4% stretch. Except that the tip cord was prepared in the same manner as in Example 1. Table 1 shows the physical properties of the dip cord thus prepared.

Comparative Example 1

The polyvinyl alcohol fiber was subjected to low-yeon in soft water 36.0TPM and tension of 0.07g / d using a ring yarn, and then two low-twisted yarns were combined and phase-leaded at 0.07g / d, and the raw cord was heat-treated under -3% stretch. Except that the tip cord was prepared in the same manner as in Example 1. Table 1 shows the physical properties of the dip cord thus prepared.

Comparative Example 2

The polyvinyl alcohol fiber was subjected to low-yeon in soft water 36.0TPM and tension 0.23g / d by using a ring yarn, and then two low-twisted yarns were combined and subjected to high-performance at 0.25g / d, and the raw cord was heat-treated under -4% stretch. Except that the tip cord was prepared in the same manner as in Example 1. Table 1 shows the physical properties of the dip cord thus prepared.

TABLE 1

division CS and Dipping Conditions Treatment Code Properties Continuous Power (Lower / Stage) (g / d) Stretch during heat treatment (%) DPU (%) Raw cord strength (kg) Shrinkage (%) Adhesive force with rubber (kg) Fatigue resistance (%) Deep code strong (kg) Deep Code Strength Utilization (%) Example 1 0.12 / 0.15 -3 6.5 33.2 0.3 19.1 93 36.9 82.1 Example 2 0.10 / 0.12 - 2 7.0 32.2 0.7 18.2 91 36.0 80.1 Example 3 0.15 / 0.17 - 4 6.0 34.3 0.2 19.8 95 36.5 81.1 Comparative Example 1 0.07 / 0.07 -3 12.5 29.1 0.4 14.7 50 31.6 70.2 Comparative Example 2 0.23 / 0.25 - 4 3.0 26.1 0.3 13.2 70 28.1 62.4

Based on the test results of Table 1, when the lower cord and the upper twist yarn tension is 0.12 to 0.17 when the deep cord (Example 1-3) prepared according to the present invention has a yarn tension of 0.07 or 0.23 (Comparative Example 1, Compared to 2), the strength of raw code is not only very good, but also the fatigue and deep code utilization is greatly improved.

Example 4

A radial tire manufactured using the polyvinyl alcohol deep cord prepared according to Example 1 of the present invention as a carcass ply has a carcass layer having a radially outer fly turnup, and the carcass layer includes one layer. Installed. At this time, the specifications of the cap fly cord and the carcass cord were as shown in Table 2 below, and were oriented at a 90 degree angle with respect to the circumferential intermediate surface of the tire. The fly turn-up 34 was to have a height of 40 to 80% with respect to the tire maximum cross-sectional height. The bead part 35 has a bead core 36 formed of 4 × 4 high strength steel wire having a diameter of 0.95 to 1.00 mm and a bead filler 37 having a hardness of shore A hardness of 40 or more. The belt 38 is reinforced by a belt reinforcement layer consisting of a single layer of cap ply 39 and one layer of edge ply 44 at the top thereof such that the cap fly cord in the cap ply 39 is parallel to the circumferential direction of the tire. Placed.

Comparative Example 3

A tire was manufactured in the same manner as in Example 4, except that a polyvinyl alcohol deep cord prepared in Comparative Example 1 was used as a cord material for manufacturing a tire.

[Comparative Example 4]

A tire was manufactured in the same manner as in Example 4, except that a cord material for manufacturing a tire was used with a deep cord obtained by twisting ordinary rayon multifilament with 1650 denier / 3 sum and a soft water of 36.0 TPM.

[Comparative Example 5]

A tire was manufactured in the same manner as in Example 4, except that a cord material for manufacturing a tire was used with a deep cord twisted with a conventional polyethylene terephthalate 1500 denier / 2 sum and a soft water of 36.0 TPM.

[Table 2]

Example 4 Comparative Example 3 Comparative Example 4 Comparative Example 5 Cap fly Material nylon nylon nylon nylon Specification (d / ply twisted yarn) 840/2 840/2 840/2 840/2 Strong (Kg) 16.2 16.2 16.2 16.2 Modulus of elasticity (g / d) 30 30 30 30 Carcass Material Polyvinyl alcohol deep cord of Example 1 Polyvinyl Alcohol Deep Cord of Comparative Example 1 Rayon Polyethylene terephthalate Specification (d / ply twisted yarn) 1500d / 2 1500d / 2 1650d / 3 1500d / 2 Strong (Kg) 36.9 31.6 24.5 22 Modulus of elasticity (g / d) 120 120 120 70 tire Flat ratio 0.60 0.60 0.60 0.60 Carcass floors One One 2 One Cap fly floor 2 2 2 2

The 215/60 R15 V tire manufactured according to Example 4 and Comparative Example 3-5 was mounted on a 2000cc class passenger car, and the noise generated in the vehicle was measured while driving at a speed of 60 km / h, thereby preventing noise in the audible frequency range. (dB), and the steering stability and ride comfort were evaluated by an experienced driver by driving a test course in units of 5 out of 100 points, and the results are shown in Table 3 below. Durability is based on FMVSS 109's P-metric tire endurance test method, measuring 38 ° C (± 3 ° C) and 85, 90, 100% of the tire's nominal load. A total of 34 hours was used to determine the pass (OK) when no trace of bead separation, cord cutting, belt separation, etc. was found in any part of the tread, sidewall, carcass cord, inner liner, or bead. .

Table 3

division Example 4 Comparative Example 3 Comparative Example 4 Comparative Example 5 Tire weight (kg) 9.65 9.89 10.42 10.08 Ride 100 98 98 95 Steering stability 100 98 97 95 durability OK OK OK OK Uniformity 100 97 99 97 Noise (dB) 61.4 62.2 62.1 63.2

From the test results of Table 3, the tire according to the present invention (Example 4) can be seen that the weight of the tire is sharply reduced compared to Comparative Example 4 using only the rayon multifilament in the carcass, and also in terms of performance In the case of the present invention (Example 4) using the polyvinyl alcohol deep cord prepared according to the present invention for carcass, the effect was excellent in terms of riding comfort, steering stability and noise reduction compared to Comparative Examples 3, 4 and 5, It can be seen that the tire uniformity is also improved.

According to the present invention, the polyvinyl alcohol fiber having a gel structure is twisted with high tensile strength when twisting, thereby minimizing the strong reduction and preventing penetration into the raw code of the RFL solution when immersed in the dipping liquid, thereby improving fatigue resistance as well. By providing a high relaxation polyvinyl alcohol deep cord by giving a high relaxation during the heat treatment, it is possible to produce a rubber reinforcement deep cord excellent in fatigue resistance. The polyvinyl alcohol deep cord prepared as described above is particularly excellent in adhesive strength with rubber of 12 to 50 kg, total denier of 1000 to 6000 dare, cutting load of 10.0 to 65.0 kg bar, passenger car tire It can be used advantageously as a cord.

In addition, the polyvinyl alcohol deep cord of the present invention can overcome the disadvantage that the conventional polyethylene terephthalate fiber has a low adhesive strength with rubber, and also can compensate for the disadvantage that the rayon multifilament is relatively strong, The treatment cords formed from these are excellent in adhesive strength and strength and can be usefully used as reinforcements for rubber products such as tires and belts or for other industrial uses.

According to the present invention, by applying the deep cord made of the polyvinyl alcohol multifilament of the present invention to the carcass layer of a pneumatic radial tire for passenger cars, it is possible to improve the adhesive strength with rubber and to improve durability, ride comfort and steering stability of the tire. Satisfactory results can be obtained.

While the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims. .

1 is an example schematically showing a polyvinyl alcohol wet-dry spinning process according to the present invention.

Figure 2 is a schematic diagram showing the structure of a tire for a passenger car manufactured using a polyvinyl alcohol deep cord according to the present invention.

※ Brief description of the main symbols in the drawing

1: Gear Pump 2: Spinning Nozzle

3: polyvinyl alcohol filament 4: solidification bath

5: solidification liquid 6: roller

31: tire 32: carcass layer

33: code for reinforcing the carcass layer 34: fly turn-up

35: bead area 36: bead core

37: Bead Filler 38: Belt Structure

39: cap fly 40: belt fly

41, 42: belt code 43: tread

44: edge fly 45: cap fly code

Claims (3)

A radial pneumatic tire having a flatness of 0.65 or less, comprising: a pair of parallel bead cords and at least one radial carcass ply wound around the bead core and a belt layer laminated on the outer periphery of the carcass; Radial pneumatic tire comprising a circumferential belt reinforcement layer formed on the outer circumferential side of the carcass layer comprises a polyvinyl alcohol deep cord, and at the same time has the following physical properties. (1) 30 kg or more of strength, (2) elongation of 6% or more, (3) 15 kg or more of adhesion to rubber, (4) fatigue resistance of 80% or more, (5) fineness of 1000 to 6000 denier, (6) 3% shrinkage under The method of claim 1, The polyvinyl alcohol deep cord radial pneumatic tires, characterized in that the yarn tension is 0.08 ~ 0.20g / d at the time of giving the lower and upper edges and 300 to 450 TPM. The method of claim 1, Radial pneumatic tire, characterized in that the carcass ply is used in one or two layers.