KR20230121366A - Cord fabric for pneumatic tire - Google Patents

Abstract

The present invention relates to cord paper for tires for pneumatic tires, and EPI (End per Inch) increases and then decreases one or more times from the center to the edge direction, and the EPI of the outermost part is designed to be lower than the EPI of the center part and the center edge. EPI becomes uniform, minimizing dent defects in finished tires and improving uniformity performance, which has the effect of giving a sense of stability during high-speed driving.

Description

Cord fabric for pneumatic tire {Cord fabric for pneumatic tire}

In the present invention, the EPI (End per Inch) increases and decreases more than once from the center to the edge direction so that the EPI of the rolled product becomes uniform, and the EPI of the outermost part is designed to be lower than the EPI of the center part and the center edge. it's about

The fiber tire cords used in PCR tires are largely divided into two types. One is the cap ply located on the steel belt on the cross section of the tire structure, and the other is the body ply located in the direction of the cross section of the tire structure. is that The uses of the two are different, but the cap ply is used to prevent the steel cord from being separated by centrifugal force while driving, and is used by winding it in the direction of tire travel. The body ply is an essential element for maintaining the shape of a pneumatic tire. It also plays a role in preventing the outer diameter of the tire from growing any further even if the air pressure is inflated beyond the specified value, as well as maintaining the handling and riding performance of the tire. Wind it in the direction and use it. Among them, the body ply plays an important role in determining tire performance and being responsible for safety, so to prevent the body ply from being damaged by external forces while driving, a tough rubber member called the sidewall is added on the cord to protect the body ply. It also protects against shock.

As the body ply has to withstand high air pressure, it is important to arrange it at regular intervals within the pneumatic tire to evenly handle the pressure. Since each code in this relatively narrow area receives a relatively small amount of air pressure compared to other areas, a dent defect (Fig. 1) that looks more depressed than other areas occurs on the side of the tire exterior. In addition, the tire rotates at high speed after being installed on the vehicle. If the spacing of the cords is not constant, the stiffness of the tire is irregularly distributed during high-speed rotation, leading to poor performance such as noise from the tire or shaking of the vehicle body. .

In order to prevent such defects in advance, tire manufacturers require cord manufacturers to arrange and fix cords at specific intervals, which are generally recorded in the tire manufacturer's product requirements, and cord manufacturers must satisfy the requirements. We manufacture and supply cord paper after fixing cords, which are weft threads, using weft threads to maintain a specific distance.

Currently, cord manufacturers are making and supplying products with almost constant EPI from the edge to the center in accordance with the requirements of tire manufacturers, and tire manufacturers apply a thin layer of rubber at about 90 ° C to the supplied cord paper and then cool it to room temperature. Through the production of rolled products. At this time, the width of the cord paper is about 2 to 5 cm smaller than the width of the rolling material, and the width of the rolling material usually has a width of around 150 cm.

The rubber material used in the rolling process has rheological characteristics in that it swells and has good flowability when the temperature is high, but slowly shrinks and decreases flowability when the temperature is lowered. When rolling cord paper in the rolling process, tire manufacturers roll cord paper by introducing rubber at a sufficiently high temperature in order to utilize the rheological properties of rubber. The rubber, which has improved flowability under high temperature, penetrates between cords and bridges the rubber between cords. It forms and also serves to increase the adhesive strength with the adhesive treated on the surface of the cord.

The central part of the main roll used to combine rubber and cord in the rolling process is made convex to have a gradient of about 3 to 8/1000 compared to the edge and has a surface temperature of about 90 ° C, which is This is to utilize the rheological properties of rubber according to the temperature like the bar. Considering this, when the behavior of the rolled material is examined in more detail for each part, the central part of the rolled material is rolled relatively thinly by the central gradient while passing through the rolling rolls, and then when the temperature drops to room temperature, the rubber shrinks and shows the desired thickness. Other parts of the rolling material also shrink as the temperature of the rolling material decreases, but the thickness exceeds the target thickness when it is a certain distance from the center.

As cord paper is put into the rolling process, it naturally follows the behavior of the input rubber, and EPI is also affected by the shrinkage of rubber and the rolling roll gradient to form the final rolled product EPI. The shrinkage behavior of the rolled product follows only the shrinkage behavior of the rubber, but since the cords that do not shrink in the width direction are arranged at irregular intervals between the rubber, the shrinkage behavior of the entire width of the rolled product becomes more complicated.

In order to understand this simply, if it is assumed that the cord paper manufactured by the conventional design technology is put into rolling, the EPI distribution from the center to the edge is uniform, and as it passes through the rolling mill, the center and the outermost part conform to the shrinkage behavior of rubber. EPI is higher than before passing through the rolling mill, and especially in the case of the outermost part, since one side is empty and there is no weight hindering shrinkage, the degree of shrinkage can be much greater.

In order to use it in the tire manufacturing process, the thickness of the rolled material must be uniform from the center to the edge, so it is necessary to mechanically pull this heterogeneous area to lower the thickened area due to rubber shrinkage to the target thickness. Inside, various types of expansion devices such as Expander Roll (aka Banana Roll) and Triocanter are operated.

As mentioned several times before, rolling stock tends to get thicker closer to the edge, which can be worked closer to the target thickness and EPI by stretching the rolling stock with a widening device. However, if the rubber of the rolled product is not homogeneous or if the widening device is operated excessively, the thickness and EPI change of the rolled product are not constant in the width direction, and if this is severe, the adhesive bond between the cord and rubber may fall off during the widening operation. can The rolled product is characterized in that it can only widen but does not shrink, and since the cord and rubber are adhered to the rolled product, it is difficult to recycle because the time and cost required to separate the rubber and the cord once rolled are high. In the end, since all rolled products whose widening operation is incorrect are subject to scrap, even a skilled rolling technician for a long time is inevitably passive in the widening operation. And if the edge EPI of the rolling material is high, it can be solved by manually removing the problem area on the edge side in the next process, the cutting process. is given priority, and edge EPI defects are usually left unresolved. After all, for this reason, the general EPI tendency of rolled products takes on a U-shape in which both sides are gradually higher than the center when measured in the full width direction.

In particular, among the total width of the rolled product of about 150 cm, the EPI of the region of about 10 cm at the outermost part on both sides rapidly increases (see the EPI distribution results of the rolled products of Comparative Examples 1 to 3 in FIGS. 2 to 4), which is the following in the tire or tire manufacturing process cause problems such as

Pneumatic passenger tires secure high-speed stability by arranging cords in a direction perpendicular to the rolling direction. The cutting process of jointing the edges is essential, and in this case, an overlap joint method in which edges overlap each other by a certain amount is generally used. However, as described above, the overlap joint method overlaps the outermost edges of the rolling stock, so eventually the jointed part has a higher code density than other parts, and the joint part causes stiffness distribution unevenness in the finished tire, and the overlap position on the finished product is dented. It can be connected to visible dent defects, and it can also be connected to poor uniformity performance of tire products. Therefore, workers in the preparation process frequently check the state of the edge EPI before the edge parts become a joint, and if the EPI is above the process tolerance level, they remove the edge of the rolling material and then put it into joint work, but this is a measure that depends on the skill of the operator. Therefore, it is not a fundamental measure, and therefore, it is difficult to prevent resources from being wasted with only the measures currently being taken.

Tire manufacturers, who were aware of this problem early on, are developing and applying a method of changing the joint method of cord paper to a butt method rather than an overlap method. The butt joint method is not universally applied because defects do not cause significant performance degradation, and it is applied only to the production of cord paper for some high-performance tires.

Cord manufacturers also tried to suppress the increase in EPI at the edges of rolling products by developing a method of giving various EPI to cord paper to compensate for this problem, but as the conventional production target was the uniformization of EPI of cord paper, the above problem was completely solved in the prior art. Not resolved. In order to solve the above problem, Patent Document 1 proposed a cord paper configuration in which the EPI is lowered from the center to the edge, but this is due to the gradient of the rolling roll and the shrinkage characteristics of the rubber. As a technology that has not been reflected, when the above proposal is actually applied, there is a limitation that the EPI of the entire width is uneven while the EPI around the center part moves more than necessary.

Republic of Korea Patent Publication No. 10-2000-0040986

In order to solve the above problem, the present invention designs cord paper for pneumatic tires so that the EPI increases and then decreases one or more times from the center to the edge, but the EPI of the outermost part is smaller than the EPI of the center and the center edge. EPI aims at providing a uniform rolled product.

A cord for a pneumatic tire according to an embodiment of the present invention includes a central portion positioned at the center in the width direction; Central edge portions disposed on both sides of the central portion; and an outermost portion disposed on both sides of the outermost shell in contact with the central edge. At this time, the EPI increases and then decreases one or more times from the center to the edges, but the EPI of the outermost part is smaller than the EPI of the center part and the center edge.

The central part may be divided into one or more sections, the central edge part may be divided into one or more sections, and the outermost part may be divided into two or more sections.

The central edge may be divided into two or more sections, and the EPI of at least one of the two or more sections may be greater than the EPI of the central section.

The EPI of the central edge may be smaller than the EPI of the central part.

the anomaly rate of the outermost part is 94% to 100%; The sum of the reductions in the anomaly rate of the outermost part is -8% to 0%; And the sum of the reduction of the anomaly rate of the central portion, the central edge portion, and the outermost portion may be -16% to 0%.

Since the rolled product manufactured by rolling the cord paper for pneumatic tire according to the present invention has a uniform EPI, even if an overlap joint is made between the edges, the change in stiffness of the joint area is minimized, thereby reducing dent defects of the finished tire. It has the effect of giving a sense of stability during high-speed driving by minimizing and improving uniformity performance.

1 is a photograph of a tire with a dent defect.
Figure 2 is a graph showing the EPI distribution results of the cord paper and rolled paper of Comparative Example 1.
Figure 3 is a graph showing the EPI distribution results of the cord paper and rolled paper of Example 1.
Figure 4 is a graph showing the EPI distribution results of the cord paper and rolled paper of Comparative Example 2.
5 is a graph showing EPI distribution results of cord paper and rolled paper of Example 2.
6 is a graph showing the EPI distribution results of cord paper and rolled paper of Comparative Example 3.
7 is a graph showing EPI distribution results of cord paper and rolled paper of Example 3.
8 is a graph showing EPI distribution results of cord paper and rolled paper of Comparative Example 4.

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Singular expressions include plural expressions unless the context clearly dictates otherwise.

Hereinafter, the present invention will be described in more detail.

A cord for a pneumatic tire according to an embodiment of the present invention includes a central portion positioned at the center in the width direction; Central edge portions disposed on both sides of the central portion; and an outermost portion disposed on both sides of the outermost shell in contact with the central edge. At this time, the EPI increases and then decreases one or more times from the center to the edges, but the EPI of the outermost part is smaller than the EPI of the center part and the center edge.

The overall width of cord paper for pneumatic tires varies depending on the case, but in most cases it is about 150 cm. For ease of description below, the overall width of the cord paper is assumed to be about 150 cm, but the overall width of the cord paper is not limited thereto and may be larger or smaller than 150 cm.

When the overall width of the cord paper is about 150 cm, the width of the central portion may be about 80 cm, but is not limited thereto and may be larger or smaller than 80 cm. When the width of the central part is about 80 cm, the central part may be divided into one or more sections, and in this case, the width of each section may be about 80 cm.

When the overall width of the cord paper is about 150 cm, the width of the central edge may be about 25 cm, but is not limited thereto and may be larger or smaller than 25 cm. When the width of the central edge is about 25 cm, the central edge may be divided into one or more, two or more, or three or more sections, and when divided into three sections, each section may have a width of about 8.3 cm.

When the overall width of the cord paper is about 150 cm, the width of the outermost portion may be about 10 cm, but is not limited thereto and may be larger or smaller than 10 cm. When the width of the outermost part is about 10 cm, the outermost part may be divided into two or more or three or more sections, and when divided into three sections, each section may have a width of about 3.3 cm. As described above, since the overlap joint method is a method in which the outermost edges of the rolling material overlap each other, it is necessary to delicately control the EPI change of the outermost edges. Therefore, the outermost part was divided into more sections compared to the interval compared to the central part and the central edge part.

The EPI of the cord paper for a pneumatic tire according to the present invention increases and then decreases one or more times from the center to the edge, but the EPI of the outermost part is smaller than the EPI of the center part and the center edge. The design so that the EPI of the cord paper increases and then decreases more than once from the center to the edge is in consideration of the difference in shrinkage between the center and the center edge due to the gradient of the rolling roll and the shrinkage characteristics of rubber. to make it even Designed so that the EPI of the outermost part is smaller than the EPI of the central part and the central edge, the outermost part is placed on the outermost part during rolling, so one side is empty and there is no weight that hinders shrinkage, so it can shrink more than the central part and the central edge. Because. Therefore, the present invention may not be evaluated as a product with excellent EPI distribution at the time of cord paper import inspection by a tire manufacturer because the EPI is not designed uniformly across the entire width of the cord paper, but the rolled paper manufactured by rolling the cord paper according to the present invention The results of the EPI distribution of water can be evaluated excellently.

Hereinafter, for ease of explanation, cord paper for a pneumatic tire having a total width of 150 cm is divided into a total of 13 sections across the entire width. A total of 13 sections are A (left), B (left), C (left), D (left), E (left), F (left), G, F (right), E (right), D (right) ), C (right), B (right), and A (right), and A (left) and A (right) are symmetrical to each other based on the center line of G, and this is the same for sections B to F.

First, the G section is a section in which the central part is divided into one section, and the width interval is about 80 cm.

F (left), E (left), and D (left) are sections in which the central edge disposed on the left side of the central part is divided into three sections with equal width intervals. ), named D (left). F (right), E (right), and D (right) are sections in which the central edge disposed on the right side of the central part is divided into three sections with equal width intervals. ), and named D (right). Each width of F (left), E (left), D (left), F (right), E (right), and D (right) is about 8.3 cm.

C (left), B (left), and A (left) are sections that are in contact with the central edge disposed on the left side of the central part and the outermost edge disposed in the outermost part is divided into three sections with equal width intervals, and are placed on the left side of the central part. They were named C (left), B (left), and A (left) in the order closest to the central edge. C (right), B (right), and A (right) are sections that are in contact with the central edge disposed on the right side of the central part and the outermost edge disposed in the outermost part is divided into three sections with equal width intervals, and are placed on the right side of the central part They were named C (right), B (right), and A (right) in the order closest to the central edge. The width interval of each of C (left), B (left), A (left), C (right), B (right), and A (right) is about 3.3 cm.

However, in the case of the rolled material, since the cord paper and the overall width are not the same, the rolled material was divided into 13 sections over the entire width in proportion to each section of the cord paper.

These sections are arbitrarily set for ease of explanation, and more or less than 13 sections can be divided, and the interval of each section can be set larger or smaller.

Hereinafter, an anomaly rate and an anomalous rate reduction amount are defined.

The EPI of each section is divided by the EPI of section G and multiplied by 100 is defined as the anomaly rate of each section. For example, when the EPI of section A is 31.1 (本/In) and the EPI of section G is 32.0 (本/In), the anomaly rate of section A is 31.1/32.0 * 100 = 97.2 (%). The closer the anomaly rate is to 100%, the more uniform the EPI can be.

In order for the EPI of the outermost part of the rolling material to be within the process tolerance range and similar to the EPI of the central part, the irregularity rate of the outermost part of the cord paper may be 94% to 100%.

The reduction of the anomaly rate (%) is defined as the value obtained by subtracting the anomalous rate of the section adjacent to the G direction from the anomalous rate of each section. For example, if the anomaly rate of B(left) is 97.2% and the anomaly rate of C(left) is 97.8%, the reduction in anomaly rate between B(left) and C(left) is 97.2 - 97.8 = -0.6%. The reason why the anomaly rate of C(left) is subtracted from the anomaly rate of B(left) is that C(left) is closer to G than B(left). If the anomaly rate of D(right) is 98.4% and that of E(right) is 100.5%, the reduction in anomaly rate between D(right) and E(right) is 98.4 - 100.5 = -2.0%. The reason why the anomaly rate of E(right) is subtracted from the anomaly rate of D(right) is that E(right) is closer to G than D(right), as explained above.

In order to ensure that the EPI of all sections of the rolling material falls within the process tolerance range and the EPI is uniform, the sum of the reduction in anomaly rates at the outermost edge of the cord paper is -8% to 0%, -6% to 0%, -4% to 0%, or - It may be 2% to 0%.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only to illustrate the present invention, and the present invention is not limited by the following examples.

Cord paper sample manufacturing

Example 1, Comparative Example 1 and Comparative Example 4

After spinning and stretching in the same spinning process using PET chips with the same production LOT, the yarn was twisted using an Allma twisting machine and woven using the Picanol loom under conditions of 1,839 warp yarns and 12.5 mm weft density. Thereafter, heat treatment was performed at a high temperature of 200 degrees or more with a heat treatment machine of Litzler to manufacture cord paper in PET 1300d/2 x 32EPI standard. At this time, EPI for each section of each manufactured code paper is shown in Table 1, Table 2 and Table 7.

Example 2 and Comparative Example 2

Same as Example 1, Comparative Example 1, and Comparative Example 4 except that the conditions of 1,540 warp yarns and 12.5 mm weft yarn density were applied during weaving in the process of preparing the cord paper samples of Example 1, Comparative Example 1, and Comparative Example 4. By doing so, cord paper was prepared according to the PET 1000d/2 x 28EPI standard. At this time, EPI for each section of each manufactured code paper is shown in Tables 3 and 4.

Example 3 and Comparative Example 3

Same as Example 1, Comparative Example 1, and Comparative Example 4, except that the conditions of 1,650 warp yarns and 12.5 mm weft yarn density were applied during weaving in the cord paper sample manufacturing process of Example 1, Comparative Example 1, and Comparative Example 4. By doing so, cord paper was prepared in accordance with the PET 1300d/2 x 30EPI standard. At this time, EPI for each section of each manufactured code paper is shown in Tables 5 and 6.

manufacture of rolled goods

After connecting the rolling stock with a rubber joint, it was confirmed that the tension was evenly distributed. Then, while going through the accumulator, the bias of the fabric was checked, and then rolling was performed at a temperature of about 90 degrees on the main roll, followed by a cooling drum and then a winding process. Rolling was performed by bundling the same manufacturing specifications, Comparative Example 1, Comparative Example 4, and Example 1 were continuously worked, then Comparative Example 2 and Example 2 were continuously worked, and then Comparative Example 3 and Example 3 A rolled product was prepared by continuous operation. At this time, 6 rolls were prepared from each cord paper sample.

EPI measurement

Right before the cord paper was wrapped, the EPI was measured at 5 cm intervals for half of the entire width (about 150 cm), and the values were reflected in a mirror image. The EPI values for each section summarized in Tables 1 to 7 below are the values obtained by averaging the EPI values measured at 5 cm intervals in the corresponding section.

When arranging in the rolling order in the manufacturing process of rolled products, the EPI of the 4th rolled product is measured at 5cm intervals across the entire width, and the measurement results are converted in proportion to each section of cord paper to each section of cord paper as shown in Tables 1 to 7 below. It was made to be comparable with each EPI value.

Examples 1 to 3 and Comparative Examples 1 to 4 EPI, anomaly rate, anomaly rate reduction amount, EPI average and standard deviation for each section of cord paper and rolled paper are summarized in Tables 1 to 8 below.

division Example 1 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 31.1 97.2 - 32.2 101.6 - - 0.6 B (left) 31.1 97.2 32.0 100.9 -0.6 - C (left) 31.3 97.8 32.0 100.9 -0.6 0.6 D (left) 31.5 98.4 31.8 100.3 -2.0 -1.3 E (left) 32.2 100.5 32.2 101.6 0.2 2.2 F (left) 32.1 100.3 31.5 99.4 0.3 -0.6 G 32.0 100.0 31.7 100.0 0.3 -0.3 F (right) 32.1 100.3 31.6 99.7 0.2 2.2 E (Right) 32.2 100.5 32.3 101.9 -2.0 1.3 D (Right) 31.5 98.4 32.7 103.2 -0.6 -0.3 C (Right) 31.3 97.8 32.6 102.8 -0.6 -2.2 B (Right) 31.1 97.2 31.9 100.6 - 0.9 A (Right) 31.1 97.2 32.2 101.6 - - sum - - -5.6 - - 3.2

division Comparative Example 1 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 32.5 103.0 - 34.3 109.2 - 0.6 1.9 B (left) 32.3 102.4 33.7 107.3 0.2 1.0 C (left) 32.3 102.2 33.4 106.4 0.3 1.3 D (left) 32.2 101.9 33.0 105.1 1.0 1.9 E (left) 31.9 101.0 32.4 103.2 0.2 1.0 F (left) 31.8 100.8 32.1 102.2 0.8 2.2 G 31.6 100.0 31.4 100.0 0.8 1.3 F (right) 31.8 100.8 31.8 101.3 0.2 0.3 E (Right) 31.9 101.0 31.9 101.6 1.0 1.3 D (Right) 32.2 101.9 32.3 102.9 0.3 1.0 C (Right) 32.3 102.2 32.6 103.8 0.2 1.3 B (Right) 32.3 102.4 33.0 105.1 0.6 - A (Right) 32.5 103.0 33.0 105.1 - - sum - - 6.0 - - 14.3

division Example 2 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 26.4 93.6 - 27.7 100.0 - -1.0 1.5 B (left) 26.7 94.7 27.3 98.5 -2.6 -3.5 C (left) 27.4 97.3 28.3 102.1 -1.2 -0.3 D (left) 27.8 98.5 28.4 102.4 -0.8 -0.8 E (left) 28.0 99.3 28.6 103.2 0.3 3.1 F (left) 27.9 99.0 27.7 100.1 -1.0 0.1 G 28.2 100.0 27.7 100.0 -1.0 -0.2 F (right) 27.9 99.0 27.6 99.8 0.3 -2.0 E (Right) 28.0 99.3 27.1 97.8 -0.8 1.0 D (Right) 27.8 98.5 27.4 98.8 -1.2 1.2 C (Right) 27.4 97.3 27.7 100.0 -2.6 2.8 B (Right) 26.7 94.7 28.5 102.8 -1.0 -0.0 A (Right) 26.4 93.6 28.5 102.8 - - sum - - -12.7 - - 2.8

division Comparative Example 2 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 28.7 104.7 - 30.5 113.3 - 0.7 4.7 B (left) 28.5 104.0 29.2 108.6 0.4 -1.4 C (left) 28.4 103.6 29.6 110.0 - 2.4 D (left) 28.4 103.6 29.0 107.6 1.1 1.0 E (left) 28.1 102.6 28.7 106.7 1.5 4.8 F (left) 27.7 101.1 27.4 101.9 1.1 1.9 G 27.4 100.0 26.9 100.0 1.1 1.5 F (right) 27.7 101.1 27.3 101.5 1.5 -0.4 E (Right) 28.1 102.6 27.2 101.1 1.1 2.8 D (Right) 28.4 103.6 27.9 103.9 - 3.9 C (Right) 28.4 103.6 29.0 107.8 0.4 5.5 B (Right) 28.5 104.0 30.5 113.3 0.7 3.1 A (Right) 28.7 104.7 31.3 116.5 - - sum - - 9.5 - - 29.8

division Example 3 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 27.8 92.2 - 29.0 97.2 - -1.8 -0.3 B (left) 28.4 94.0 29.1 97.5 -2.2 -1.8 C (left) 29.1 96.2 29.6 99.3 -1.2 -0.5 D (left) 29.4 97.4 29.7 99.8 -1.3 0.8 E (left) 29.8 98.7 29.5 99.0 0.3 -0.7 F (left) 29.7 98.3 29.7 99.7 -1.7 -0.3 G 30.2 100.0 29.8 100.0 -1.7 3.1 F (right) 29.7 98.3 30.7 103.1 0.3 -0.8 E (Right) 29.8 98.7 30.5 102.3 -1.3 -0.8 D (Right) 29.4 97.4 30.2 101.5 -1.2 -0.2 C (Right) 29.1 96.2 30.2 101.3 -2.2 0.3 B (Right) 28.4 94.0 30.3 101.6 -1.8 -2.1 A (Right) 27.8 92.2 29.7 99.5 - - sum - - -15.6 - - -3.2

division Comparative Example 3 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 30.0 101.2 - 31.3 107.3 - 1.1 2.9 B (left) 29.7 100.1 30.5 104.4 -0.0 0.6 C (left) 29.7 100.2 30.3 103.8 0.2 1.1 D (left) 29.6 100.0 30.0 102.6 0.5 1.6 E (left) 29.5 99.5 29.5 101.0 -0.3 - F (left) 29.6 99.8 29.5 101.0 -0.2 1.0 G 29.7 100.0 29.2 100.0 -0.2 4.5 F (right) 29.6 99.8 30.5 104.5 -0.3 - E (Right) 29.5 99.5 30.5 104.5 0.5 -0.1 D (Right) 29.6 100.0 30.5 104.4 0.2 1.4 C (Right) 29.7 100.2 30.9 105.8 -0.0 2.9 B (Right) 29.7 100.1 31.8 108.7 1.1 1.4 A (Right) 30.0 101.2 32.2 110.2 - - sum - - 2.5 - - 17.5

division Comparative Example 4 cord paper rolling stock EPI anomaly rate Anomalous rate reduction EPI anomaly rate Anomalous rate reduction (本/In) (%) (%) (本/In) (%) (%) A (left) 31.1 96.9 - 33.3 104.7 - - 3.5 B (left) 31.2 96.9 32.2 101.3 -0.9 2.2 C (left) 31.5 97.8 31.5 99.1 - 1.6 D (left) 31.5 97.8 31.0 97.5 -1.2 0.3 E (left) 31.9 99.1 30.9 97.2 - -0.9 F (left) 31.9 99.1 31.2 98.1 -0.9 -1.9 G 32.2 100.0 31.8 100.0 -0.9 -1.6 F (right) 31.9 99.1 31.3 98.4 - -1.6 E (Right) 31.9 99.1 30.8 96.9 -1.2 1.9 D (Right) 31.5 97.8 31.4 98.7 - 1.6 C (Right) 31.5 97.8 31.9 100.3 -0.9 4.4 B (Right) 31.2 96.9 33.3 104.7 - 2.8 A (Right) 31.2 96.9 34.2 107.5 - - sum - - -6.2 - - 12.3

division item Comparative Example 1 Example 1 Comparative Example 2 Example 2 Comparative Example 3 Example 3 Comparative Example 4 cord paper EPI
(本/inch) Target 32.0 32.0 28.0 28.0 30.0 30.0 32.0 Average of all sections (sections A to G) 32.1 31.7 28.2 27.4 29.7 29.1 31.6 Standard deviation of all intervals (range A to G) 0.3 0.4 0.4 0.7 0.2 0.8 0.3 Anomaly rate (%) edge of both sides
0-10cm average 102.5 97.4 104.1 95.2 100.5 94.1 97.2 the outermost part of both sides
Sum of anomaly rate reductions from 0-10 cm 1.6 - 1.3 2.2 - 7.3 2.1 -8.0 - 1.9 Sum of reduction in anomaly rate in all areas 6.0 -5.6 9.5 - 12.7 2.5 - 15.6 - 6.2 rolling stock EPI
(本/inch) Target 32.0 32.0 28.0 28.0 30.0 30.0 32.0 Average of all sections (sections A to G) 32.7 32.1 28.8 27.9 30.5 29.8 31.9 Standard deviation of all intervals (range A to G) 0.8 0.4 1.4 0.5 0.9 0.5 1.1 E~G standard deviation 0.37 0.36 0.7 0.5 0.6 0.5 0.4 Anomaly rate (%) Average of 0-10 cm on both sides 106.2 101.4 111.6 101.0 106.7 99.4 102.9

Hereinafter, the process tolerance range of the EPI of the rolled product is set to Target EPI ± 1. In addition, the uniformity of the rolling product EPI is regarded as non-uniform when the standard deviation exceeds 0.5, and is regarded as uniform when it is less than 0.5.

Looking at the EPI for each section of the code paper of Example 1 in Table 1, it can be seen that the EPI of section F is greater than the EPI of section G and the EPI of section E is greater than the EPI of section F. Meanwhile, it can be seen that EPI gradually decreases from section E to section A. This shows that the EPI of the code paper of Example 1 increases and then decreases one or more times from the center to the edge, so that the EPI of the outermost part is smaller than the EPI of the center part and the center edge (see FIG. 3).

On the other hand, when looking at the EPI for each section of the code paper of Comparative Example 4 in Table 7, it can be seen that it continues to decrease from section G to section A. This shows that the EPI of the code paper of Comparative Example 4 decreases from the center to the edge (see FIG. 8).

Target EPI of the rolled products of Example 1 and Comparative Example 4 is 32. At this time, looking at the average EPI and standard deviation of the rolled material of Example 1 and the rolled material of Comparative Example 4 in Table 8, the rolled material of Example 1 had an average EPI of 32.1 and a standard deviation of 0.4, and the rolled material of Comparative Example 4 had an average EPI of 31.9. It can be seen that the standard deviation is 1.1. Looking at Figure 3, it can be confirmed that the EPI of all sections of the rolled product of Example 1 is within the process tolerance range, and the EPI of the rolled product is uniform with a standard deviation of less than 0.5. On the other hand, looking at Figure 8, it can be seen that the rolling product of Comparative Example 4 has a section in which the EPI does not fall within the process tolerance range at the center and the outer edge, and the EPI of the rolled product is not uniform with a standard deviation of 1.1.

Therefore, in order to make the EPI of the rolled product uniform and to make both the EPI of the central edge and the outer edge fall within the process tolerance range, the EPI of the cord paper increases and then decreases one or more times from the center to the edge direction, as in the present invention. It can be seen that the EPI should be designed to be smaller than the EPI of the central part and the central edge.

Looking at the EPI of the cord paper of Example 1 and Comparative Example 1 in Table 8, the cord paper of Example 1 has an EPI mean of 31.7 and a standard deviation of 0.4, and the cord paper of Comparative Example 1 has an EPI mean of 32.1 and a standard deviation of 0.3. Target EPI of Example 1 and Comparative Example 1 is 32. Accordingly, the EPI distribution of the coded paper of Comparative Example 1 having an EPI average closer to 32 and a smaller standard deviation is more uniform than that of the coded paper of Example 1.

However, looking at the EPI of the rolled products of Example 1 and Comparative Example 1 through Table 8, FIGS. 2 and 3, the EPI average of the rolled product of Example 1 is 32.1 and the standard deviation is 0.4, so the EPI of the rolled products is uniform and all sections allow the process. While within the range, it can be seen that the rolling product of Comparative Example 1 has an EPI average of 32.7 and a standard difference of 0.8, so that the EPI of the rolled product is not uniform and there is a section where the EPI does not fall within the process tolerance range at the outermost part. In addition, looking at the average irregularity rate of the outermost 0-10cm section through Table 8, Example 1 rolled material was 101.4%, which is closer to 100% than 106.2% of Comparative Example 4 rolled material, indicating that the outermost EPI is more similar to the central EPI. Able to know. Therefore, it can be confirmed that the EPI uniformity of the rolled product of Example 1 is superior to that of the rolled product of Comparative Example 1.

Similarly, through Table 8 and FIGS. 4 to 7, it can be confirmed that the rolled products of Examples 2 and 3 have excellent EPI uniformity compared to the rolled products of Comparative Examples 2 and 3.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the art do not deviate from the spirit and technical scope of the present invention described in the claims to be described later. It will be understood that the present invention can be variously modified and changed within the scope not specified.

Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be determined by the claims.

Claims (5)

a central portion located at the center in the width direction;
Central edge portions disposed on both sides of the central portion; and
Including an outermost portion disposed on both sides of the outermost portion in contact with the central edge,
Cord paper for pneumatic tires, wherein EPI (End per Inch) increases and then decreases one or more times in the direction from the center to the edges, but the EPI of the outermost part is smaller than the EPI of the center part and the center edge.
According to claim 1,
The central portion is divided into one or more sections,
The central edge is divided into one or more sections,
Cord paper for pneumatic tires in which the outermost part is divided into two or more sections.
According to claim 1,
The central edge is divided into two or more sections,
Cord paper for pneumatic tires in which the EPI of at least one of the two or more sections is greater than the EPI of the central portion.
According to claim 1,
Cord paper for pneumatic tires in which the EPI of the center edge is smaller than the EPI of the center.
According to claim 1,
the anomaly rate of the outermost part is 94% to 100%;
The sum of the reductions in the anomaly rate of the outermost part is -8% to 0%; and
Cord paper for pneumatic tires in which the sum of the anomalous rate reduction of the central portion, the central edge portion, and the outermost portion is -16% to 0%.