CN117901581A

CN117901581A - Low rolling resistance cap ply and tire

Info

Publication number: CN117901581A
Application number: CN202410163550.9A
Authority: CN
Inventors: 郭玉梅; 王其旭
Original assignee: Anhui Giti Radial Tire Co Ltd
Current assignee: Anhui Giti Radial Tire Co Ltd
Priority date: 2024-02-05
Filing date: 2024-02-05
Publication date: 2024-04-19

Abstract

The invention relates to a low rolling resistance cap ply and a tire, wherein the low rolling resistance tire comprises a tread rubber layer, a cap ply, a belt ply and a ply layer which are sequentially arranged from outside to inside, wherein the cap ply is continuously spirally wound along the circumferential direction of the tire, and the load force difference between 0.5% deformation and 3% deformation of the cap ply cord at the normal running temperature of the tire is between 0.6 and 1.3 cN/D. The invention realizes the effect of reducing the rolling resistance of the tire by optimizing the performance of the cap ply cord, in particular to the energy consumed by the cap ply at the ground contact surface of the tire by limiting the load force difference value of the cap ply cord in the variation range of the normal running temperature, thereby realizing the technical effect of drag reduction to a certain extent.

Description

Low rolling resistance cap ply and tire

Technical Field

The invention relates to the technical field of tire manufacturing, in particular to a low rolling resistance tire.

Background

In the cycle, in the running process of the automobile, nearly 1/3 of oil consumption of the automobile is used for overcoming the rolling resistance of the tire, so that the low rolling resistance tire is selected, the oil consumption can be effectively reduced, and meanwhile, the automobile is more friendly to the environment. With the implementation of the tag method and the rapid development of electric vehicles, tire manufacturers are actively developing tires with lower rolling resistance.

The existing means for reducing the rolling resistance mainly reduces the rolling resistance of the tire in terms of formulation and component weight, mainly adjusts the formulation of the tire with relatively large weight in the tire such as tread, sidewall and the like, but the formulation with low rolling resistance tends to be not wear-resistant or has reduced drivability. Or parts with a relatively large weight ratio, such as a carcass, an inner liner, RC/triangular glue, a reinforcing layer and the like, but the reduction of the weight often causes the reduction of safety performance or other characteristic loss. However, since the cap ply weight ratio is small, it is known through finite element analysis that most of rolling resistance of the tire is lost in energy consumption of the tire when the tire is driven on a hard road, the tread consumption is about 50%, the base (including cap ply) is about 20%, the belt layer is about 10%, and the side (including carcass) is about 10%. There has been relatively little research into reducing rolling resistance from the cap ply side.

In the prior art, there is very little research on reducing rolling resistance from the aspect of cap ply, and the research on the effect of cap ply on rolling resistance of tires has been advanced since 2015.

The utility model patent CN207496401U uses aramid fiber/nylon 66 composite gum dipping cord fabric to replace common steel wires and crown belts. Compared with the common radial tire of the car with the same specification, the weight is reduced by about 8 percent, and the rolling resistance is reduced by about 18 percent. However, the blend fiber cord is used for replacing steel wires, the strength of the ply is reduced, the tire pressure penetrating performance is at risk, and the safety of the tire is difficult to ensure.

The invention patent CN111086358A forms a cap ply by winding the cap ply in the circumferential direction of the tire, binds the belt ply, improves the high-speed performance, reduces the weight of the cap ply material, further reduces the rolling resistance of the tire, but has limited reduction range and maximally reduces the rolling resistance value to 3 percent.

The invention patent CN109835118B forms a cord textile layer in the form of a thin tape by spinning and placing a plurality of cord strands, rather than twisting a plurality of cord strands to form a cap ply cord. Which reduces the rolling resistance of the tire by reducing the weight, but the process is complicated and the manufacturing cost increases.

The invention patent CN108944272B improves durability and tire rolling resistance by adjusting the design of the belt ply and simultaneously applies a tensile load of 660N to the crown ply of 0.06 or less to the crown ply cord of unit number, and the maximum reduction rolling resistance value is 4%.

The invention patent CN114761253B limits the tangential modulus of the cap ply at 1.3% elongation to 200daN/mm to 650daN/mm by using 3 polyester multifilament strands or two multifilament strands of aromatic polyamide or aromatic copolyamide and one multifilament strand of aliphatic polyamide or polyester, while matching a single belt layer, thus increasing the tire rolling resistance and maximally reducing the rolling resistance value to 4%. The use of a single belt layer can reduce the strength of the belt layer, the tire puncture performance can be at risk, and the tire safety is difficult to ensure.

Disclosure of Invention

The present invention aims to provide a technical solution for improving the rolling resistance of a tire based on the improvement of the fibrous properties of the cap ply, and thus to provide a tire with low rolling resistance.

The technical proposal of the invention provides a cap ply with low rolling resistance,

The cap ply comprises cap ply cords formed by continuous spiral winding in the circumferential direction of the tire, and the difference of load force between 0.5% deformation and 3% deformation of the cap ply cords at the normal running temperature of the tire is between 0.6 and 1.3 cN/D.

Preferably, the cap ply cord has a load force difference between 0.5% deflection and 3% deflection at normal running temperatures of the tire of between 0.7 and 1.0 cN/D.

Preferably, the tire has a normal running temperature of 90-125 ℃.

Preferably, the M100 of the cap ply compound is between 2.0 and 3.0Mpa, and the M300 is between 10.0 and 14.0 Mpa.

Preferably, the M100 of the cap ply compound is 2.5Mpa, the M300 is 12Mpa, and the calendering thickness of the cap ply compound is 1.1mm.

The technical scheme of the invention further provides a low rolling resistance tire, which comprises a tread rubber layer, a cap ply, a belt layer and a ply layer which are sequentially arranged from outside to inside, and is characterized in that the cap ply is arranged between the belt layer and the tread rubber layer, the cap ply covers the belt layer, and the cap ply is any of the low rolling resistance cap ply.

The invention realizes the effect of reducing the rolling resistance of the tire by optimizing the performance of the cap ply cord, in particular to the energy consumed by the cap ply at the ground contact surface of the tire by limiting the load force difference value of the cap ply cord in the variation range of the normal running temperature, thereby realizing the technical effect of drag reduction to a certain extent.

Drawings

FIG. 1 is a chart showing the cap ply stress curve obtained by finite element analysis.

Detailed Description

The present invention will be described in detail below with reference to the drawings and the specific embodiments, and in the present specification, the dimensional proportion of the drawings does not represent the actual dimensional proportion, but only represents the relative positional relationship and connection relationship between the components, and the components with the same names or the same reference numerals represent similar or identical structures, and are limited to the schematic purposes.

The invention aims to provide a pneumatic radial tire with low rolling resistance, and the deformation of a cap ply when the tire is driven is controlled by controlling the load force difference value of the cap ply cord under different deformation, so that the relatively obvious optimization of the rolling resistance can be realized by matching with a cap ply rubber formula with low modulus.

In general, in normal running (running speed not greater than 120 km/h), the temperature of the cap ply of the tire is generally around 120 ℃, and this temperature range may float in the range of 90-125 ℃ depending on the situation. The properties of the material fibers are generally affected by temperature significantly, so that the change in mechanical properties of the cap ply fibers, such as modulus of the material, is often significant at normal temperature as compared to when the tire is running. In order to study the optimization of the rolling resistance of a tire during running, the mechanical properties of the fiber under running conditions should be considered. While the present application is described in terms of cap ply performance optimization at 120 ℃, it should be understood that the specific improvement is not limited to implementation at about 120 ℃, but rather has a range of feasibility, which may be 90-125 ℃ as described above, or other temperatures determined based on the temperature rise value at the target driving condition of the tire.

For a conventional 205/55R16 gauge semisteel radial tire, the effect of cap ply performance on tire rolling resistance was studied. First, the running state of the tire is analyzed. Four different types of cap ply cords were selected for preliminary testing and finite element analysis. Table I shows the relevant data, and FIG. 1 shows the stress curve of the cap ply.

Remarks: the state of inflation is 100% inflated and the state of load is 100% loaded under 100% inflated conditions.

Table 1: stress and strain conditions of cap ply cord

As can be seen from Table 1, the load value at 120℃of the cap ply cord at 0.5% elongation is substantially identical to the deformation and stress of the cap ply cord in the inflated state of the tire. The maximum deformation of the cap ply cord is between 3 and 4% under load. The higher the modulus of the cap ply cord, the smaller the amount of cord change, at a minimum of 3%, and if the cap ply cord has a 3% cord deflection under load, then it is apparent that the load value should be nearly identical to the load value of the cord at 3% elongation of the cord at 120 ℃.

In fact, during running of the tyre, the load conditions represent the stress conditions of the ground contact surface of the tyre, whereas the charge conditions can generally be regarded as stress conditions of the circumferential non-ground contact. The running process of the tire can be simply considered as the periodic loading and unloading of the load experienced by the tire in the circumferential direction, which causes the stress conditions at all places in the circumferential direction of the tire to change periodically during running. It can also be seen from the above table that in both the loaded and inflated state, the cap ply and the cord are deformed simultaneously, and energy is consumed by the deformed portion of the material, resulting in an increase in resistance. Therefore, the reasonable design of the cap ply reduces the performance of the cap ply in an inflated state and a loaded state, and the loss of power on the cap ply can be reduced, which is shown as the reduction of rolling resistance.

The cap ply cord maximum deformation range for normal tire application is expected to be between 3-4%. The cap ply can be reasonably and pertinently improved within the range so as to optimize the rolling resistance of the tire. The main idea is to reduce the energy loss caused by the stress change when the cap ply normally runs. Taking the maximum deformation of the inflation state as 3% and the maximum deformation of the load state as 0.5%, taking the influence of the load force difference change of the cord layer under the two states on the final rolling resistance into consideration.

The test tire specifications were 205/55R16, 245/45R18, 255/45R20, the cap ply rolled thickness was 1.1mm, and the cords in the cap ply were continuously spirally wound in the tire circumferential direction.

Comparative example 1 is a conventional cap ply material nylon 66, with a load force differential of 0.4cN/D (cN/D, cN/denier) at 120 ℃ at 3% and 0.5% deflection.

Comparative example 2 is a polyester material with a load force difference of 0.5cN/D at 120 ℃ at 3% and 0.5% deflection;

comparative example 3 is a conventional aramid and nylon 66 blend (one aramid blended with one nylon 66) with a load force differential of 1.7cN/D at 120 ℃ at 3% and 0.5% deflection.

Examples 1,2, 3, 4, 5 are all polyester materials with a load force differential of 0.8cN/D,1.0cN/D, 1.3cN/D, 0.6cN/D, 0.7cN/D at 120℃at 3% and 0.5% deflection, respectively. In practice, fiber cords that can control the load force differential between 3% and 0.5% deflection at 120 ℃ at 0.6 to 1.3cN/D include rayon cords and polyester-based cords (including but not limited to polyethylene terephthalate, polyethylene naphthalate, and the like). However, polyester-based cords are preferred because of the high cost of rayon cords.

The mechanical properties of the fibrous material are affected by the process of the precursor, twisting and dipping. The properties of the filaments are also affected by the intrinsic viscosity of the chip, the spinning speed, the cooling device and the drawing process. Meanwhile, the strength and modulus of the cord are affected by the twist degree and twisting mode of twisting and the temperature during dipping. In general, the stretching curve of a polyester material can be adjusted by adjusting the molecular weight of the crystalline regions and the degree of orientation of the amorphous regions. There have been a great deal of research in the industry as to the method of adjusting the tensile properties of polyester cords, which is not described in detail herein.

Meanwhile, conventionally, the polyester-based material has a low polarity and does not have a hydrogen bond-forming group, so that the dipping solution is difficult to penetrate into the inside of the cord, and the standard RFL dipping solution cannot cause good adhesion between the polyester-based cord and the rubber. There is a great deal of research in the industry concerning the impregnation improvement of polyester-based cords, including the use of a secondary impregnation or multiple impregnation process, a modification of the primary impregnation process and the surface modification of the polyester-based material. The polyester-based cord used in the invention is equivalent to the conventional nylon material in steam aging resistance at 100 ℃ through secondary dipping and dipping optimization, and is a mature dipping formula for suppliers.

The results in the following table can be obtained by performing experiments on the tested tires on a tire testing machine according to national standards:

Remarks: 1. the rolling resistance is the test value of each scheme/the test value of comparative example 1, and the average value of 3 specifications is taken for display;

2. the difference in load force was 3% and 0.5% of the difference in load force at 120 ℃.

Table 2: rolling resistance experimental data of different schemes

According to the experimental results, basically, if the difference of the load force at the deformation of 3% and 0.5% of the cap ply cord at 120 ℃ is controlled to be 0.6-1.3 cN/D, the rolling resistance can be reduced by 3% -5%. More preferably, the roll resistance can be reduced by 4% to 5% if the difference in load force at 120℃at 3% and 0.5% deflection is controlled to 0.7 to 1.0cN/D, such as in example 1, and the roll resistance can be reduced by about 5% if the difference in load force at 120℃at 3% and 0.5% deflection is controlled to 0.8 cN/D. With reference to the prior art, the optimization of the tire rolling resistance to 3-5% has reached and partially exceeded the average level of the prior art in the field. The improvement effect is remarkable. When the rolling resistance is reduced by adjusting the cap ply or the cap ply and the belt ply, the safety performance is often reduced, the lifting complexity is often reduced or the rolling resistance reduction range is limited.

Qualitatively, it is understood that the cap ply cord has limited binding force to the belt layer when the difference of the load force at 120 ℃ at 3% and 0.5% deformation is less than 0.6cN/D, and the cap ply component deforms greatly, so that heat generation is large, which may be a potential cause of increased energy consumption. When the difference of load force at 120 ℃ at 3% and 0.5% deformation of the cap ply cord is greater than 1.3cN/D, the modulus and rigidity of adjacent belt components and tread components are greatly different, and the lack of an effective transition of a proper cap ply leads to greater energy consumption under the interaction between different material layers of the tire, which may be one of the causes of increased energy consumption.

To confirm the utility of the solution for adjusting the load force differential of the cap ply cords, we also tested other performance performances of the experimental tires. Taking example 1 and comparative example 1 as examples, the tire detailed properties are as follows:

table 3: other performance comparisons of example 1 and comparative example 1

The experiment was continued. The maximum roll-off resistance amplitude is 5% when the difference of the load force of the cap ply cord at 120 ℃ under the deformation of 3% and 0.5% is 0.6-1.3 cN/D. In order to further reduce rolling resistance, a large number of experiments prove that the corresponding tire performance can be optimized by changing the type and the parts of carbon black and the modulus of the cap ply formula. The test results are shown in Table four.

Table 4: influence of different cap ply formulations on test results

Remarks: 1. the tire specification is 205/55R16, 245/45R18, 255/45R20, and the cap ply calendering thickness is 1.1mm;

2. the basic performance of the formula is 160 ℃ for 15 min;

3. the rolling resistance is the test value of each scheme/the test value of comparative example 1, and the average value of 3 specifications is taken for display;

M100 is the 100% tensile stress of the tire;

m300 is the 300% tensile stress of the tire;

TS is the tensile strength of the tire.

Continuing table 4: influence of different cap ply formulations on test results

As shown in the test results of Table 4, by adjusting the type and the number of the carbon black and the modulus of the formula, the M100 of the cap ply formula is 2.0-3.0 Mpa, the M300 is 10.0-14.0 Mpa, and the load force difference between 3% and 0.5% deformation of the cap ply cord is 0.6-1.3 cN/D at 120 ℃, so that the rolling resistance of the tire is reduced by 7% -10%. The M100 of the cap ply formula is 2.5Mpa, the M300 is 12Mpa, and the load force difference between 3% and 0.5% deformation of the cap ply cord is 0.8cN/D at 120 ℃, so that the rolling resistance of the tire can be reduced by 10%. Wherein, by comparing the g and h, if only changing the part of the existing carbon black, the effects of M100 in 2.0-3.0 Mpa and M300 in 10.0-14.0 Mpa are difficult to achieve, and the preferable means is to use carbon black with large particle size or white carbon black to replace the commonly used small particle size carbon black for cap ply (the traditional formula generally uses small particle size carbon black N3XX series). It is demonstrated by examples a, b, c, d and comparative examples c, d, e, f: the N5XX series and N6XX series carbon black are used, the use parts of the carbon black are reduced by 5 to 10 parts, the modulus of the sizing material is proper, and more preferably, the rolling resistance reducing effect is better by using the N6XX series carbon black. As demonstrated by examples e, f and comparative example f: the functional white carbon black is used, and meanwhile, the reduced part is 0 to 20 parts, and the modulus of the sizing material is proper.

To confirm the effect of changing cap ply compound composition on other effects of the tire, the present application also tested other data for tires made from the combination of comparative example 1 and example 1, comparative example a and example b in the above table. The test results are shown in Table 5. The data in the table can show that the tire rolling resistance can be reduced by about 7% -10% by controlling the load force difference between 3% and 0.5% deformation of the cap ply cord at 120 ℃ to be 0.6-1.30 cN/D, and matching with the cap ply rubber material with low modulus of M100 between 2.0 and 3.0Mpa and M300 between 10 and 14Mpa, and the tire safety performance is not reduced.

Table 5: test experimental data for test tires of different combinations

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and various modifications and improvements made by those skilled in the art to which the invention pertains will fall within the scope of the invention as defined by the appended claims without departing from the spirit of the invention.

Claims

1. A cap ply with low rolling resistance is characterized in that,

2. The low rolling resistance cap ply of claim 1, wherein the cap ply cord has a load force differential between 0.7 and 1.0cN/D at a tire normal running temperature of 0.5% deflection and 3% deflection.

3. The low rolling resistance cap ply of claim 1, wherein said tire has a normal running temperature of 90-125 ℃.

4. A low rolling resistance cap ply according to any one of claims 1-3, wherein the cap ply compound has an M100 between 2.0 and 3.0Mpa and an M300 between 10.0 and 14.0 Mpa.

5. The low rolling resistance cap ply of claim 4, wherein the cap ply compound has an M100 of 2.5MPa and an M300 of 12MPa, and the cap ply has a calendered thickness of 1.1mm.

6. A low rolling resistance tire comprising a tread rubber layer, a cap ply, a belt layer and a ply layer which are sequentially arranged from outside to inside, wherein the cap ply is arranged between the belt layer and the tread rubber layer, the cap ply covers the belt layer, and the cap ply is the low rolling resistance cap ply according to any one of claims 1 to 5.