KR20020090841A - Composite comprising organic fibers having a low twist multiplier and improved compressive modulus - Google Patents

Abstract

The present invention provides an improved fiber reinforced product comprising at least two plies. Each layer of ply is a cord made from (a) rubber and (b) melt-spun non-metallic multifilament fibers with a twist coefficient of about 375 or less, a stress of at least 1.7 grams / denier at an elongation of 1%, and an initial compression coefficient At least about 7 grams / denier, wherein the two or more plies have a fiber orientation angle of at least about 23 °. The composite is useful as a tire belt in a tire of a passenger car.

Description

FIELD OF THE INVENTION COMPOSITE COMPRISING ORGANIC FIBERS HAVING A LOW TWIST MULTIPLIER AND IMPROVED COMPRESSIVE MODULUS

Tires are high-performance composites that (1) develop longitudinal (circumferential) forces during acceleration and braking, (2) develop lateral forces during cornering, (3) support vertical loads, and (4) impact It should be possible to provide cushioning. Thus, the tire belt contributes significantly to the cornering properties, deformation of the footprint (on road surface contact) and forward movement by providing stiffness to the tire. Increasing the tensile coefficient in the circumferential direction of the tire improves the efficiency of driving force transmission from the axle to the tire and ultimately onto the road surface. When the driver drives the car, cornering forces are generated, which place the contact patch (tire area or footprint area in contact with the floor), and the belt under the control of the in-plane shear force. When the hardness of the tire belt is high, the tire tread is in flat contact with the road surface in the footprint area, thereby improving cornering and treadwear. The importance of these belts makes them a goal of improved use in high performance tire applications.

The main concern for agricultural and off-road tires is how efficiently the force is transmitted through the tire. The goal of performance is greatly influenced by the coefficient of the circumferential direction (or longitudinal direction) of the tire belt. The high circumferential tensile modulus for the tire can be interpreted as a high degree of force transfer from the rotation of the wheel to the forward movement of the motor vehicle. However, maximizing the above characteristics of the belt negatively affects the properties of the in-plane shear modulus. In addition to the power transmission, in passenger tires, i.e. tires used in passenger cars used on a daily basis, riding comfort, handling and treadwear are of interest. Riding comfort is affected by the out-of plane bending of the tire belt. The lower out-of-plane bending coefficient allows tire treads to easily cover road obstructions, minimizing vertical bending transfer to the tire axle. Handling, for example cornering, is influenced by the in-plane bend of the tire belt. As the number of in-plane shears of the tire belt increases, the handling response also improves. However, since the desired level of power transmission must be maintained, the coefficient of circumferential direction cannot be reduced below the possible level of optimizing the above characteristics. Thus, the belt design of passenger car tires is different from the design of off-road and agricultural tires in that a number of belt factors need to be optimized to achieve the desired functional purpose.

Angle-ply belt composites for pneumatic tires are typically made by stacking two or more plies of filament-reinforced rubber sheets in a cross direction. Reinforcing filaments are usually unidirectional in the sheet. When incorporating the unidirectional ply into a tire, an arbitrary angle is formed between the reinforcing filament and the circumferential direction line of the tire. The angle is usually 20 ° to 23 °. This conventional manufacture of belt composites produces a belt in which the cut filament rim is located along the circumferential full length of the belt rim. Thus, the individual reinforcing filaments of the angle-ply composite are not connected to each other, which impairs the mechanical and fatigue properties of the composite due to its ability to move independently rather than collectively at the ends of the cut filaments. Cut cord ends also exhibit material discontinuities that cause undesirable stress concentrations.

The use of steel wire cords for reinforcing filaments is the most common method for existing tire belts. This is because the steel cord has suitable compressive and tensile properties for belt reinforcement. However, steel cords have a low tenacity and a high density, so the weight of steel is a disadvantage in that the fuel economy is adversely affected. In addition, steel-reinforced belts require cap plies or overlays for optimal function at high speeds, where low density synthetic filaments help nest heavy steel cords by overlapping the cut edges of steel cords and sharp cuts of steel cords Helps reduce stress concentration at the end, increasing tire life and high speed capability. Tires made of synthetic filament-reinforced belts do not require the use of a cap ply, resulting in savings in labor and material costs. In addition, the use of steel reinforcement belts makes tire regeneration impractical if the tires are corroded. Furthermore, tire recycling of steel-belt tires becomes more difficult (due to excessive wear of the tire grinding device) and increases the proportion of lower rubber debris (ie, no guarantee of absence of metal). Overall, recycling of steel-belt tires is less cost effective than recycling synthetic organic filament belt tires.

Given the many disadvantages associated with the use of steel for reinforcing tire belts, it is highly desirable to replace steel as a lightweight material as a reinforcing material. Advantageously, the tensile strength of lightweight synthetic filaments such as PEN, PET, aramid and nylon is much better than the tensile strength of steel when compared to a given fiber weight. Since tires are generally designed for strength, the difference results in fewer cords per tire when synthetic filaments are used. Disadvantageously, however, the synthetic fibers generally have a lower compression coefficient compared to steel wire and produce a composite with smaller in-plane shear modulus. The low in-plane shear modulus of the tire belt is detrimental to the cornering coefficient and treadwear characteristics of the pneumatic tire.

There are several possible approaches to increasing belt function when reinforced with synthetic fibers. Generally the approach is to introduce additional plies to the belt and / or to use three-dimensional reinforcements. The latter approach involves stitching the plies together to tack the belt plies together, folding the plies, or braiding or interweaving.

U.S. Patent 3,616,832, U.S. Patent 3,854,515 and International Publication WO 98/14336 have attempted to replace steel cords in tire belts with synthetic materials. U. S. Patent 3,616, 832 discloses four-ply belts having a ply angle of 5 degrees to 35 degrees; As an example, a ply angle of 15 degrees was employed. U. S. Patent 3,854, 515 discloses replacing a steel belt with four plies, all with 30 [deg.] Ply angles in the belt. Polyesters used as reinforcements have a lower degree of polymerization than those used in conventional polyester cords with twist restrictions. International publication WO 98/14336 discloses the use of polyesters with a special cord structure in belts designed for heavy duty applications such as off-road tires and for use in agricultural radial carcass tires. Examples use polyethylene terephthalate (PET) fibers and have a conventional ply angle of 20 ° on a 4-ply belt, and a ply angle of 15-30 °, preferably 17-23 ° on a 2-ply belt. It is starting. A total of three publications disclose the use of conventional ply angles as synthetic reinforcing materials, but do not consider the low in-plane shear modulus problem inherent in the tire belt compared to steel reinforced materials.

The use of varying bias ply angles has been applied in the design of drive belts. U. S. Patent 5,211, 609 discloses a two-ply composite drive belt with two layers having a bias ply of approximately 45 degrees to 75 degrees (preferably 70 degrees) with respect to the longitudinal axis of the belt. The bias angle is chosen to balance the forces of the lateral forces that affect the belt tracking. There is no disclosure of the composition of the reinforcing cable, nor is there any indication for application to the structure of the tire belt.

Although the use of stitching in laminated composite designs has been disclosed, nothing discloses an advantageous effect on in-plane shear modulus, nor does it disclose or imply the use of stitching in tire belt composites. The use of stitching in composites with laminated structures has been disclosed in US Pat. Nos. 4,331,495 and US Pat. Nos. 5,185,195, 5,198,280 and 5,591,993. The disclosure at 495 does not disclose the arrangement of reinforcing filaments in adjacent plies, discloses other stitching patterns, is not intended for flexible elastic composites, and discloses the benefits of stitching in in-plane shear modulus. Or implied. The disclosures at 195 and 280 employed stitching to consolidate layers of penetration resistant articles with two or more adjacent stitching paths that are less than 0.125 inches apart. The disclosure of 933 teaches a loose stitching process to achieve satisfactory 'delamination' in penetration resistant products. M. Cholakara, B.Z. Jang and C.Z. In Wang, "Mechanical Properties of 3-D Composit" (ANTEC'89, pp 1549 to 1551) discusses the effect of stitching of Kevlar and epoxy resin laminates on damage tolerance by improving interlaminar shear strength. It is starting. The document does not disclose unidirectional fibers, there is no detailed description of stitching, does not imply the use of stitching in tire belt composites, nor does it consider in-plane shearing.

Composites employing overlapping plies are disclosed, for example, in US Pat. No. 5,535,801, which discloses the use of aromatic polyamide fiber-reinforced ribbons with a width of 5 to 15 mm and zigzag overlapping between the rim of the belt. The patent makes no mention of the code features for the code structure and the reinforcement code, nor does it disclose any particular ply angle. Although the zigzag belt only contains a continuous fiber reinforcement with a cutting cord at both ends of the ribbon, it will have many seams and it will be difficult to prepare a given narrow width ribbon. U.S. Patent 4,210,189 discloses a belt formed by reinforcing cords folding a single wide ply across the width of a single ply into a structure having three folds and four overlapping plies. The cutting cord ends are across the width of a single unfolded ply, and when folded, the cutting cord ends exist through the circumference of the folded belt structure. The patent does not mention code structure and code specificity for enhanced code. Belt ply angles disclosed for use in radial tires are 0 ° to 30 ° and belt ply angles disclosed for use in bias tires are 20 ° to 55 °. U. S. Patent 3,830, 276 also discloses a folded belt wherein the reinforcement cord is cut and the cut end is along the circumference of the folded belt structure. A braided structure is disclosed, for example US Pat. No. 4,830,781 discloses a woven tire reinforcement component that is used as the basis for the tread and at least the sidewall area of the pneumatic tire. The interwoven structure is made using a coated continuous cord reinforcement, preferably comprising a single cord located in a rubber coating. The patent does not mention code features for code structure and enhancement code.

Another disclosure of composites using polyethylene naphthalate fibers includes: Japanese publication 30210-1997 (1997.2.4), Japanese publication 276704-1996 (October 22, 1996), Japanese publication 310251-1995 (1995.11.28), Japanese Publication 193608-1997 (July 29, 1997), and Japanese Publication 142101-1997 (1997.6.3) and International Publication WO 98/4726

After extensive research on composite design, the present invention uses only non-metallic reinforcements to ensure that significantly lighter weight belts can have comparable or better circumferential tensile modulus and in-plane shear modulus as compared to steel belts. By doing so, the improvement of the existing tire belt design was achieved. This combination of properties is the result of combining the properties of the synthetic filament cord with the novel composite structure. Important code properties include the initial tensile and initial compressive coefficients.

The present invention relates to a product or component of the product having an improved combination of in-plane shear modulus (IPSM) and circumferential tensile modulus, which improves the resistance to various stresses generated during use of the article. It is. More particularly, the present invention relates to rubber products reinforced with nonmetallic multifilament, for example, in products subjected to tensile and shear stress during use, as found in tires, in particular belts for radial tires and transmission drive belts. It is about.

1 illustrates a two-ply composite useful in the practice of the present invention.

2 shows four-ply, other ply-angle composites useful in the practice of the present invention.

Figure 3 shows a 3-ply, different ply-angle complex in the practice of the present invention.

Figure 4 illustrates a continuous chain stitch pattern useful in the practice of the present invention.

Figure 5 illustrates a cross-stitch pattern useful in the practice of the present invention.

Figure 6 illustrates a zigzag stitch pattern useful in the practice of the present invention.

7 illustrates a series of folding steps useful in the practice of the present invention.

8 shows a tire belt splicing method without a cutting edge.

9 shows the relationship between the fly angle and the two properties of the 2-ply composite.

Detailed description of the preferred embodiment

As used herein, 'multifilament fibers' include yarns, twisted yarns, cords, etc., but excludes monofilaments with a Taesumdo (> 500d). The term 'code' as used herein includes a structure with zero twist coefficient because it has no code twist.

The term 'ply' as used herein refers to a monolayer in the composite of the present invention. The ply may be continuous or discontinuous with other plies in the composite. The other plies and subsequent plies have one or more folds in them, and if not folded, will be a single piece of unidirectional fiber-reinforced rubber sheet. These plies can be mixed with one or more other plies to form a braided structure. Thus, the two ply composite has two layers of unidirectional fiber-reinforced rubber sheets, which sheets can be continuous with one or more folds, can be braided or non-continuous, and if separate, It may be a separate sheet.

As used herein, 'ply angle' or 'orientation angle' means an acute angle formed between the unidirectional reinforcement fibers in the rubber and the circumferential direction of the tire belt or between the longitudinal directions of the product in a typical composite product.

The term "twist coefficient" as used herein is a calculated amount that reflects the structure of the cord and is associated with the helix angle of the constituent yarn, or the helix angle of the twisted filament with respect to the axis of the cord in the yarn. Lowering the kink coefficient lowers the helix angle. The following equation is used to calculate the twist coefficient:

Twist Coefficient = tpi × (TD) ^½ (1)

"Tpi" refers to the number of turns per inch of cord twist, and "TD" is the total nominal denier of the cord. The TD can be calculated by multiplying the number of yarns used to make the code by the denier of the yarn, or simply by adding the denier of the individual component yarns when mixed deniers are used in the code.

As is known in the art, increasing the number of twists can compensate for the poor fatigue properties of a given synthetic yarn. However, high kinks cause lowering of the tensile and compression coefficients, which adversely affects tire belt function. On the other hand, reducing the kink in the cord lowers the fatigue life of the yarn. PEN yarns have inherently better fatigue resistance than other ultrahigh modulus synthetic organic yarns such as aramid, and have inherent high adhesion. Therefore, it is possible to reduce the twist of the PEN cord without lowering fatigue life to an unacceptable level and without reducing adhesiveness to an unacceptable level. Thus, by using a low twist effectively providing a sufficiently high compression coefficient for the tire belt, while maintaining sufficient fatigue life and good adhesion for durability, successful use of PEN over steel in the tire belt is possible.

For use as a reinforcing cord, PEN is a preferred fiber. However, any melt-spinable multifilament fibers can be used as long as the code characteristics presented can be satisfied. Melt-spun fibers are, for example, polyethylene naphthalate (PEN), and polyesters such as polyethylene terephthalate (PET) and liquid crystalline polyester; Polyolefin ketones (POK); Polyamide fibers such as nylon 4,6, and nylon 6T. The fibers used as reinforcements in the examples of the invention are polyester, polyethylene naphthalate, and in all examples using PEN fibers, PENTEX® polyethylenenaphthalate fibers supplied by AlliedSignal Inc. were used. PEN fibers useful in the practice of the present invention may be conventional PENs, such as those disclosed in U.S. Patent 3,616,832 or British Patent 1,445,464, or dimensionally stable PEN fibers, as disclosed in U.S. Patent 5,397,527, designated generally, all of which It is specified by reference to the extent necessary to complete the disclosure.

Cords useful for the composites of the present invention have a twist coefficient of less than about 375, more preferably less than about 360 and most preferably of 310 or less. Thread and cord twist can be performed using any useful device, including ring twisters and direct cablers. While balanced twists, that is, the fly (thread) twist is essentially the same as the cable (cord) twist, have been used for the embodiments of the present invention, but the physical properties and the fatigue life are dependent on the cable twist and by the thread fly twist Unbalanced cord kinks are also possible because they are not dependent. Particularly useful in the present invention is a yarn of about 500 to about 6000 denier. The denier per filament is at least about 2 dpf and is preferably about 5 dpf to about 10 dpf.

Cord dipping for the PEN codes used here was done using dip consisting of Aerosol OT (3.6 grams), distilled water (2045 ml), gum tragocanse (1.2 g), and Aracast XU-AY-238 epoxy (150 g). Conventional dual dip treatment with a preliminary immersion stage, with dip pick-up of 0.7% by weight. The pre-soaked cord passes through two ovens under 6% constant tensile elongation, with the first oven at 300 ° F (80 seconds) and the second oven at 450 ° F (40 seconds). The final immersion is followed by ammonialation RFL, with dip pick-up being 0.5% by weight. The cord is then passed through two ovens and allowed to relax by 2%. The first oven is 300 ° F (80 seconds) and the second oven is 450 ° F (60 seconds).

Cords useful for the present invention have a stress of at least 1.7 grams / denier (g / d) at 1% elongation. Codes useful for the present invention also have an initial compression coefficient of at least about 7 g / d, more preferably at least 9 g / d, most preferably at least 9.5 g / d.

Total cord denier and EPI (ends per inch) are determined by measures of tire size, structure and function. Nowadays, finite element modeling (FEM) is often used to determine the required mechanical properties of the tire belt. The belt demands in turn define the amount and space of the cord. As a general rule, cord deniers require as low as possible to provide the thinnest (lightest) plies while providing good belt durability. The close cord spacing improves the elastic modulus of the composite ply in the direction perpendicular to the cord axis. For the angle ply of the present invention, the closer spacing can enhance the tensile properties of the tire in the circumferential direction. The fractional distance between the cords can be described by the term ribbon rivet which is commonly used. "Rubber rivet" is the fractional rubber density perpendicular to the cord axis, which can be calculated by the formula:

Rubber rivet = 1- (EPI) ^＊ (cord diameter) (2)

At this time, the cord diameter is measured in inches. In the present invention, a ribbon rivet of about 0.10 to 0.25 is preferred for a 2-ply composite comprising a 2-ply continuous edge composite, and for the outer plies of the 3- and 4-ply composites. Higher ribbon rivets (up to about 0.86) are useful for 4-ply continuous edge composites as well as inner plies / plies of 3- and 4-ply composites.

In the embodiment of the present invention, the reinforcing cord is about 6000 d, 4 × 4, and has the following characteristics: Twisting coefficient 310, cutting strength of 8.3 g / den, initial modulus of elasticity of 173 g / den, final elongation of 6.4%, 1 Stress at 1.7% elongation, 4.4g / den at 3% elongation, and 6.9g / den at 5% elongation.

The composite product can use any suitable rubber suitable for the required end use. For use in belts for reinforcing pneumatic tires for passenger cars, typical tire belt rubber raw materials include, for example, natural / SBR (styrene butadiene rubber) rubber blends and sulfur curing agents. The rubber used here is a rubber raw material used commercially.

In a first embodiment of the present invention, the two ply belts are constructed using unidirectional fiber-and-rubber composite sheets, wherein the PEN fiber cords meet the aforementioned parameters. Composite sheets are made using existing process methods such as conventional tire cord calendering, filament winding, prepregging of unidirectional composites, and pultrusion. The unidirectional sheet is then bias cut to a particular ply angle, and these two sheets are stacked to create a two-dimensional stack of ± angle ply structures. For the lab scale sample used here, the uncured laminate composite is subjected to moderate pressure to consolidate two plies into an integrated multi-ply composite. The final step involves curing the composite by conventional methods of heating to a moderately elevated temperature, applying pressure for a time long enough to vulcanize (cure) the rubber matrix. It should be noted that in a typical tire manufacturing process the curing step takes place with the belt already assembled in the actual tire.

1 shows a two ply belt. In the composite structure 5, the two plies 7 and 9 are adjacent to each other and the parallel reinforcement filaments 11 of the first layer are not parallel to the parallel reinforcement filaments of the second layer. The ply angle 13, ie the angle formed between the circumferential axis of the belt 15 and the reinforcing fibers 11 in the composite, is important in this embodiment. The two plies are balanced positively (ply 9) and negatively (ply 7), have the same ply angle, and have an optimal combination of in-plane shear modulus and tensile modulus in the circumferential direction, i. In order to achieve a combination comparable to a ply steel-reinforced belt, the ply angle of the two ply composite of the present invention is preferably at least about 23 ° to 35 °, more preferably from about 25 ° to about 35 ° and most preferably Is about 26 ° to about 35 °.

In a second embodiment of the invention, the preparation of the 3- and 4-ply composites having a combination of different ply angles begins with a series of steps as was done for the two ply composites. Unidirectional fiber-and-rubber composite sheets are made using existing process methods such as conventional tire cord calendering, filament winding, prepregging of unidirectional composites, plutrsion, and the like. The unidirectional sheet is then bias cut at a particular ply angle, wherein the cut sheets are stacked to create a two-dimensional stack of ± angle ply structures. Figure 2 Figure 3 shows 4-ply and 3-ply versions of the above embodiments of the invention, respectively.

In FIG. 2, complex 17 consists of four plies 19, 21, 23 and 25. Two inner plies 21 and 23 are inserted between the two outer plies 19 and 25. When used on a tire, one of the outer plies 19 or 25 may be the innermost ply radially relative to the axis of rotation of the chai, the other outer ply radially the outermost ply and the tread of the tire It can be a close fly. Each ply is reinforced with parallel, unidirectional fibers 11. Each 13 is an acute angle formed between the reinforcing fibers 11 and the circumferential (or longitudinal) tire axis 15 of the composite, called a 'ply angle'. In the figure, plies 19 and ply 21 have a positive fly angle, while plies 23 and 25 have a negative fly angle. Although, in general, the ply angle of each ply in a composite can vary while satisfying the symmetry conditions for the circumferential direction, examples of useful angles include the outer ply ± 23 ° and the inner ply ± 45 °. It is not limited to this. For example, the orientation angle in the ply is + / + /-/-or-/-/ + / + or + /-/-/ + from the radially innermost ply to the radially outermost ply. Or-/ + / + /-or + /-/ + /-or-/ + /-/ +.

In FIG. 3 the three ply complex 27 consists of two outer plies 29 and 33 and one inner ply 31. For use on a tire, one of the outer plies 29 or 33 can be the innermost ply radially about the axis of tire rotation, and the other outer ply is radially closest to the outermost ply and tire tread. Can be a fly. Each ply is reinforced with parallel, unidirectional fibers 11. Angle 13 is an acute angle formed by the circumferential (or longitudinal) tire axis 15 of the reinforcing fiber 11 and the composite, called a ply angle. Ply 29 has a negative fly angle, and ply 33 has a positive fly angle. The outer ply preferably has a non-metallic reinforcement at an angle from about ± 23 ° to 35 °. The single inner ply 31 inserted between the outer plies 29 and 33 has a non-metallic reinforcement with a ply angle of about ± 0 ° to 5 °, most preferably about 0 °.

Another embodiment of the invention involves the introduction of three-dimensional components into the composite, ie stitching. As in other embodiments, the manufacture of stitched belt composites involves a series of steps. The rubber composite is assembled and cured as above, except that the uncured, assembled composite is stitched before curing.

Stitching of the composite requires a flexible reinforcing material such as synthetic fibers. Steel is unsuitable for stitching in the present invention because of its inflexibility. The most industrial fibers can be used, such as PEN, PET, nylon, rayon or aramid. Preferred denier for the stitching fibers is 500 to 6000. Stitching fibers have certain mechanical properties. Stitching of the laminate can be performed manually or by machine. The stitching holes have a diameter approximately equal to the stitching cord diameter and can be pre-drilled into the stack prior to stitching or formed almost simultaneously with the fibers passing through the thickness of the stack. The stitching hole flows into and seals it while curing at the final raised temperature. The stitches are initially tensioned and remain intact after curing. Stitching preferably covers the entire surface of the laminate composite to maximize the improved in-plane shear modulus. A small portion of the stitching of the straight edge or belt will reduce the delamination of the laminate, but the in-plane shear modulus will not be improved. It is not necessary to tie the stitching fiber ends. Due to the subsequent curing at elevated temperatures, stitching becomes a permanent part of the composite.

Regarding the pattern used in the first embodiment of the present invention, any pattern that results in an improvement in the in-plane shear step can be used. Some conventional stitches are preferred and are detailed above for clarity purposes. Preferred continuous chain stitches are shown in FIG. 4 where the stitch 35 indicated by the solid line is on the front side of the laminated composite 36 and the stitch 37 indicated by the dashed line is on the back side of the laminate composite. Line 15 indicates the orientation of the circumferential axis of the product. For example, the stitching fiber exits the composite at point 39 and travels along the front of the composite, penetrates to the back at point 41, then moves along the back of the composite and back through the composite at point 43 , Cross the composite again at point 45. Similarly, the stitching fiber exits the composite at point 47, moves along the surface, then enters the back at point 49, moves along the back of the composite, then reverses through the composite at point 41, then traverses the composite again at point 51 Shout This pattern continues over the entire surface of the composite belt. Each 53 is described below.

Preferred zigzag stitches are shown in FIG. 5. In Figure 4, stitch 35 is on the front side of the laminated composite and stitch 37 is on the back side. Angle 53 is an angle formed between the circumferential axis 15 of the stitched and stitched composite. In the zigzag pattern, the fiber goes from point 55 across the front of the composite to point 57 where it penetrates the composite to the back and moves back to point 59 to repenetrate the thickness of the laminate along the front to point 61. Move. The pattern continues over the entire surface of the composite belt.

The preferred third stitch pattern, cross stitch, is shown in FIG. 6 and is similar to a zigzag pattern except that the stitching fibers cross each other. Thus, the stitching fiber travels from point 63 across the surface of the composite to point 65 and then crosses back here to point 67, where it again penetrates the composite to the front and moves to point 69. Similarly, the stitching fibers travel from point 71 across the surface of the composite to point 73 where they cross over to the back and move to point 75, where they repenetrate the composite back to the front and move to point 77. As in FIGS. 4 and 5, stitch 35 is on the front side of the laminate composite and stitch 37 is on the back side. Angle 53 is an angle formed between the stitch and the circumferential axis 15 of the stitched composite.

If necessary, the three stitch types can be used in combination. Of the three combination forms, the most preferred is a continuous chain stitch used throughout the surface of the belt. Useful ply angles for the practice of stitched embodiments range from about 23 ° to 35 °, preferably 23 ° to 30 °, and the most preferred value is 23 °.

In the stitching pattern, it is highly desirable that each 53 formed by stitching about the circumferential axis 15 of the tire belt (or the longitudinal axis of the general product) is ± 45 °. When the stitch angle 53 is this amount, the maximum advantage for improved in-plane shear count is obtained. Most preferably, the immediately adjacent parallel lines of the stitch are about 0.35 inches apart. Thus, the stitch density, defined as the number of stitch lines per inch, is preferably about 3 lines per inch. The stitch size, for example, the length of the fibers from point 39 to point 41, is most preferably on the order of about 0.7 inches. Thus, there is about 1.4 stitching per inch in one linear row of stitching.

In another embodiment of the invention, the preparation of the composite with the non-cut edge begins with the same sequence of steps as the other ply angled composites stitched in the production of the unidirectional composite sheet. However, depending on the folding method employed, the unidirectional composite sheet may or may not be cut to produce a particular ply angle. U.S. Patent 3,473,594; 3,863,695; And 4,210,189 describe the folded belt concept previously used in the tire industry. In addition, the present invention discloses a series of new folding steps, as shown schematically in FIG. 7, which provides a belt having a non-cut folded edge and a fiber reinforcement that is necessarily continuous at the belt edge. "Must be continuous" means that there are few free ends of the cord on the outer rim of the belt. Referring to FIG. 7A, a fiber-reinforced rubber composite 79 with fiber reinforcement 11 parallel to the longitudinal direction of the sheet is shown. In FIG. 7B, composite 79 is folded along line 85 to bring point 81 to point 83. Each 13 between line 85 and border 87 is the resulting ply angle of the folded complex. Once folded, the composite is flipped once as shown in FIG. 7C and folded along line 93 to bring point 89 to point 91 as shown in FIG. 7D. Line 95 indicates the width of the tire belt. The twice folded composite is again inverted as shown in FIG. 7E, and folded along line 101 as shown in FIG. 7F, bringing point 97 to point 99. The three times folded composite is turned upside down and folded continuously in the same way until the length of the folded composite is of sufficient length for a given function, ie the tire belt. Thus, even two foldings can provide sufficient length for a given function. The folded belt is cured using pressure and elevated temperature as described above. The folding can be done manually and can be done using any suitable automated process.

Cylindrical belts can be formed by forming two end-to-end splices from a spirally folded two-ply composite of uncut edges. New splices were developed as shown in FIG. 8. In this figure, the reinforcing filaments 11 are parallel to the original edge 105 of the unfolded uniaxial composite sheet. Terminals 107 and 109 are single plies and, when overlapped, are formed as belt regions where two-ply splices are folded with the same thickness. The reinforcing cord of the folded belt cuts along one side to form a cut notch 111 in the splice region. To minimize the impact of the cutting cord, a flap 113 is included at the other end of the single ply. The folded complex is bent to place a single ply end 107 on a single ply end 109 to form a ring. Flap 113 is folded along line 115 to fit the cut notch 111 region. The flap 113 has a complementary shape with the notch 111 so that when the flap 113 is folded to the notch 111 it completely fills the notch 111. By doing so, there is no cutting cord at the rim of the final spliced belt composite. In the case of the 4-ply composite, the ends 107 and 109 are 2-ply and, when overlapped, the 4-ply splice is formed with the same thickness as the folded belt region. In a braided belt, two plies are braided together to form a cylindrical sleeve. The sleeve is then squeezed to produce two necessarily flat plies, parallel to the longitudinal axis of the cylindrical sleeve.

Current reinforced products can be used in reinforced products that require improved properties resulting from the present invention. The use is a tire belt or a motorcycle tire for a passenger car. Still other applications include transmission belts, V-belts and conveyor belts.

How to measure

a. code

Initial tensile modulus was measured according to ASTM. Each sample was fixed with the appropriate pretension specified in ASTM D885. At an elongation value of 1%, the stress was taken from the same data used to calculate the initial tensile modulus and calculated using the actual denier of the cord. The stress at 1% elongation is related to the load at 1% elongation, ie at specific elongation, but standardized for denier of yarn.

The initial compression coefficient of the cord was measured using composite specimens based on Goodrich disk fatigue specimens. Except for the control cord sample without the cord added, instead of a single cord, five cords are placed in each rubber filled mold hole. During molding of the sample the cord is constrained under a minimum tension of about 0.01 g / den. Each compressed sample was in the shape of a rectangular prism approximately 0.49 inches wide, 0.43 inches thick and 1.25 inches long. The top and bottom of each sample are ground to form parallel planes. Compression coefficients are measured by uniaxially compressing a sample between platens at a crosshead speed of 0.5 in / min. The compressive coefficient (E _composite ) of the _composite is determined using the initial straight portion of the compressive stress-elongation curve (before the code / sample distortion) and is calculated by the formula:

E- _composite = slope x gauge length / width (3)

Here, "tilt" is the slope of the initial straight line portion in the load-to-displacement curve, "gauge length" is the initial composite gauge length, and "width" refers to the initial composite cross-sectional area. The cord elastic modulus (E _cord ) is calculated assuming iso-strain conditions, where the rubber / cord composite modulus (E _composite ) is determined by the mixing law as follows;

E _Composite = (V _Code × E _Code ) + (V _Rubber × E _Rubber ) (4)

Where "E" is the initial compression coefficient and "V" is the volume fraction of the component in the sample. The correction factor is applied to the V _code calculation taking into account the empty space in the code bundle. The code volume assumes that 70% is solid and 30% is empty.

b. Complex

The circumferential tensile test was performed on a rectangular composite sample with a width of approximately 0.75 inches and a gauge length of 6 inches and a sample aspect ratio of 8 (length divided by width) according to ASTM D 3039. Samples were evaluated on an Instron 8511 tester running Series ® data collection software or on an Instron 4505 tester running Series ® software at a constant crosshead speed of 0.2 in / min. The data were collected on a computer connected to an Instron tester via a GPIB interface.

The maximum load is the load at break described on ASTM D 3039.

The circumferential tensile modulus (indicated by the tensile modulus in the table of example data) was calculated by the following equation:

Circumferential tensile factor = (F / Δl) l _o / w _o (5)

"F / Δl" is the slope of the load displacement curve in the elongation range of 1% to 4%, "l _o " is the initial sample gauge length, "w _o " is the initial sample width. The unit obtained is pound-force / inch (lbf / in).

In-plane shear modulus (IPSM) tests were performed in accordance with ASTM D 4255 standard guidance to evaluate the in-plane shear properties of the composites. Rail shear (method A) was used. For stitched composite samples, the Series® software was tested on an Instron 4505 tester at room temperature (˜23 ° C.) and 55% relative humidity at a constant crosshead rate of 0.2 in / min. For other fly angle samples, tests were carried out on an Instron 8511 tester at a constant crosshead rate of 0.2 in / min under room temperature (-23 ° C.) and relative humidity of air circulation. The data were collected on a computer connected to an Instron tester via a GPIB interface. The equation used to calculate IPSM is:

IPSM = (F / Δw) w _o / 2l _o (6)

Where "F / Δw" is the slope of the shear load versus displacement curve, "w _o " is the width of the initial sample and "l _o " is the initial sample gauge length. The unit obtained is lbf / in.

Tensile modulus and in-plane shear modulus values are expressed here in pound-force / inch. The thickness of the sample was not included in the calculation, eliminating the devaluation of the possible values due to restraint on the possible rubber sheet thickness. The composites prepared in this study are thicker than can be made with conventional calendering methods. Furthermore, the use of such units is consistent with those traditionally used in the tire industry.

The out-of-plane bending coefficient (OPBM) test was performed by a dynamic bending test using a three-point bending geometry with a central load on a simple support compensation. The sample was initially placed at 3 mm in position of the instrument and the total rotational displacement was 1.4 mm below the initial position distance. The test frequency was 10 Hz. The sample had a length of about 1.6 inches and a width of 0.4 inches. The thickness between the complexes changed. OPBM was calculated by the formula:

OPBM = (F / Δl) / w _o (7)

Where "F / Δl" is the slope of the dynamic load vs displacement curve and "w _o " is the initial sample width.

Flexural fatigue tests were performed on rectangular composite specimens of 10 inches and 0.75 inches in length. Specimens were tested on a Scott compression fatigue tester commonly used to assess fatigue and cord adhesion of reinforced rubber composites in the tire industry. Samples are placed around a 0.5 inch diameter spindle and placed under a total load of 70 pound-forces (lbf). Rotate (bend) the sample at a rate of approximately 266 revolutions per minute (-4.4 hertz) until breakage occurs. A description of the total number of revolutions until broken and the breaking mechanism was recorded for each sample.

The data in the table are the results obtained by testing two or more samples. The reported values are average values.

Summary of the Invention

The problem to be solved is to increase the inflation shear rate of tire belts reinforced with synthetic filaments, such as polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), to benefit from reduced tire weight, easier regeneration and recycling, To provide circumferential tensile modulus and in-plane shear modulus comparable to steel-reinforced tire belts. The problem is due to the inherently low compression coefficient of synthetic organic fibers when compared to steel cords. The problem has been solved in the present invention, which is a fiber reinforced product comprising at least two plies, in which each layer of ply has a twist coefficient as a cord made from (a) rubber and (b) melt spinnable nonmetallic multifilament fibers. And a cord having a stress of at least 1.7 grams / denier at an elongation of 1% and an initial compression coefficient of at least about 7 grams / denier at an elongation of 1%, wherein the two or more plies have a fiber orientation angle of at least about 23 °.

The present invention improves the main properties of tire belts reinforced with non-metallic filaments by modifying or converting the design of existing steel reinforced tire belts to achieve a combination of these properties that is comparable to or better than the combination found in existing steel reinforced belts. Could.

In a first preferred embodiment, the in-plane shear modulus and the tensile modulus in the circumferential direction were improved by employing an unusual ply angle for the two ply composite.

In a second embodiment, for 3- and 4-ply composites, an additional ply angle is employed, with the addition of low cord density and relatively low cord weight to offset undesirable losses in the circumferential tensile modulus. By adding a ply of, an optimal combination of in-plane shear modulus, out-of-plane bending modulus and circumferential tensile modulus was achieved. Alternatively, one can combine unidirectional plies with different ply angles and specific ply sequences. More specifically, two plies having a ± 45 ° angle are fitted to a particular ± 23 ° angled outer ply or a single ply of about 0 ° to an outer ply of ± 30 °. The implementation of this embodiment is further advantageous in that no new device is required.

In a third embodiment, an excellent combination of circumferential tensile modulus, in-plane shear modulus, and out-of-plane bending modulus was achieved by introducing a three-dimensional reinforcement, ie stitching, into the angle ply composite. In-plane shearing can be comparable to traditional steel-reinforced belts. In more detail, non-metallic flexible reinforcements, such as PEN, PET, aramid and nylon, were used to stitch through the thickness of the composite with unidirectional nonmetallic filament-reinforced rubber sheet layers.

In a fourth embodiment of the present invention, a continuous reinforcement cord composite of a non-cut edge is disclosed. The method significantly improves the tensile and fatigue properties of the composite obtained, by removing the cutting filament ends along the belt edge, compared to conventional cutting edge composites. The continuous rim can be prepared by folding the belt as disclosed in US Pat. No. 4,210,189 or by the novel helical folding method disclosed herein. Synthetic filament cord is flexible and suitable for the above folding operation. A variation of this embodiment is to press the braided sleeve to form a two-ply, uncut edge, continuous stiffener cord composite. Also disclosed is a novel splicing method.

The present invention is advantageous because the steel cord is completely replaced by synthetic fibers without sacrificing tire performance. Furthermore, weight reduction can have a positive impact on the fuel economy, tires can be regenerated, tire recycling becomes less difficult and significantly advantageous.

Other advantages of the present invention will become apparent from the following detailed description, the accompanying drawings and the appended claims.

Comparative Codes A, B, C, D, E, F and G, and Starting PEN Codes 1-6 (Examples of the Invention)

A series of cords were produced with varying polymer compositions and cord structures. The purpose of a series of cords is to describe the relationship between the twist coefficient and the code characteristics for each polymer type. Comparative codes A, B and C are made from commercially available aramid yarn. Comparative codes D, E and F are from commercially available PET company. Starting PEN code 1-6, PEN Inc. was made using PENTEX (R) which is commercially available from AlliedSignal. Initial tensile and initial compressive coefficients were measured on each of these cords. These data are shown in Table 1 and the stress is stress under 1% elongation.

1.n.a means not available. Data are not available because the code processing conditions are not comparable, or the preparation of the sample is inappropriate or incomparable.

As shown in Comparative Codes A, B and C, the low twist coefficient aramid cord has a high initial tensile coefficient, but the compression coefficient of the cord is very low. Tire belts made of such cords have poor treadwear characteristics and poor cornering coefficients due to low compression coefficients. As shown in Comparative Codes D, E, F and G, cords made from PET have good compression coefficients but relatively low initial tensile values. Starting PEN codes 1 to 6 have high levels of initial modulus of elasticity and good compression coefficient values. Unless stated otherwise, starting PEN code 5 with nominal denier 6000, actual denier 6500 and dpf of about 7 was used continuously to make the rubber and cord composites of the examples and comparative examples A below.

Comparative Example A and Example 1-6

For Comparative Examples A and Examples 1-6, the base rubber-and-fiber composite sheets are the same, a 21 EPI unidirectional prepreg sheet of starting PEN code 5 coated with Resorcinol formaldehyde latex (RFL) It was prepared by laminating with a commercially used tire rubber. The following belts were manufactured to explore the relationship between the fly angle and two belt properties important in passenger car belt designs: in-plane shear and tensile modulus. Each belt is a cut edge composite similar to that shown in Figure 1 with two plies. Each uncured laminate was cured under pressure of 100 psi at 150 ° C. for 30 minutes. The fly angle varies from 0 ° to 45 °. Using Comparative Example B as a comparison point, data is reported in Table 2. Data in Table 3, Comparative Example B, is a conventional 2-ply steel-reinforced belt with a ply angle of 23 °. The data in Table 2 are also shown in the graph of FIG. 9, where solid dot is relative-plane shear modulus data and hollow rectangle is relative tensile modulus data.

1. Data compared with conventional steel-reinforced belts with a fly angle of 23 °; Values greater than 1 indicate that the PEN-reinforced belt exceeds the value of the steel-reinforced belt.

The data clearly shows that the in-plane shear modulus increases with increasing ply angle, while the tensile modulus decreases. In addition, the data indicate that the belt angle should be optimized for the PEN reinforced composite in order to meet the needs of the steel belt criterion, clearly showing that the optimal PEN belt angle is different from that used in steel.

The data surprisingly show that for PEN-reinforced composites, the optimum value of the bias ply angle with regard to maximizing the in-plane shear modulus and tensile coefficient is a ply angle greater than 23 ° typical for steel belts. For example, Examples 2, 3, 4 and 5, having ply angles of 25 °, 26 °, 30 ° and 35 °, respectively, had a reasonable and preferred combination of in-plane shear modulus and tensile modulus. It is reasonable to believe that all angles from 25 ° to 35 ° likewise have the desired combination of in-plane shear modulus and tensile modulus. The data also show that when the ply angle is greater than 30 °, the in-plane shear modulus of the PEN reinforced composites outperforms the equivalent conventional steel belts.

Comparative Example B

Comparative Example B is a two ply, steel-reinforced tire belt that represents a typical commercial belt, in which the unidirectional reinforcement was oriented at ± 23 °. Steel cords range from -14,000 deniers at 22 EPI per ply. Laminations were cured at standard tire molding conditions to form the final composite structure.

Example 7-11

Example 7 was also a two-flybelt similar to that shown in Figure 1, consisting of the same as in Examples 1-6, but using starting PEN code 2 at 26 EPI in a unidirectional prepreg sheet. The fly angle was 28 degrees.

Examples 8 and 9 are both 4-ply composites similar to those shown in FIG. 2, reinforced with RFL-coated starting PEN Cord5. In both examples, the outer plies 19 and 25 were ± 23 ° and the PEN code was 21 EPI per ply. In both cases, two inserted inner plies 21 and 23 were ± 45 °. In Example 8 of the invention, the PEN reinforcement was 4EPI per fly, while in Example 9 it was 8EPI. In both examples, the sequence of plies in constructing the laminated composite was -23 ° / -45 ° / + 45 ° / + 23 °.

Examples 10 and 11 were 3-ply belts similar to those shown in FIG. For Example 10, the fly angles of the two outer plies 29 and 33 were ± 30 ° and the PEN reinforcement was 21 EPI per ply. Inner ply 31 was approximately 0 ° with respect to the circumferential axis of the composite and the PEN cord reinforcement was 4 EPI per ply. Similarly, for Example 11, the fly angles of the two outer plies 29 and 33 were ± 30 ° and the PEN reinforcement was 21 EPI per ply. For the internal ply of Example 11, the PEN cord reinforcements were 1000/1/3, 5.6 × 5.6 at 16EPI. Since the cord structure has a twist coefficient of approximately the same as the starting PEN code 5, it has the same initial tensile coefficient and initial compression coefficient as the cord. The data for this example is shown in Table 3.

Example 1 tested the additional properties listed in Table 3.

Example 1 shows that the use of starting PEN code 5 in a typical belt structure would be comparable to the maximum load and OPBM values comparable to the typical two-ply steel reinforcement belt of Comparative Example B, and the tensile modulus and fatigue over conventional steel belts. It shows that it has a lifetime. However, the in-plane shear modulus decreased compared to conventional steel belts. Example 7 includes a PEN code with a low twist coefficient (as reported for starting PEN code 2 in Table 1 above) 63 in the ply, the use of increased EPI per ply, and the use of a ply angle of 28 °. It shows that IPSM can be achieved which is comparable to the existing steel belt.

From the results summarized in Table 3 for Examples 8-11 of the invention, it can be seen that the belt composites made with additional plies and various ply angles have IPSM values approaching the values of the steel-reinforced composites. Examples 8 and 9 show that increasing the internal fly's EPI for 4-ply composites results in an increase in IPSM. An additional EPI increase in the inner ply is expected to further increase the IPSM, exceeding the IPSM value of the steel-reinforced belt. The practicality of this increase in EPI is limited only by belt thickness and weight limitations and cord diameters.

Examples 10 and 11 show comparable or improved IPSM values when the 3-ply composite has a 30 ° fly ply angle and an internal ply 0 ° compared to the existing steel reinforcement belt of Comparative Example B. In other words, it can have improved circumferential tensile modulus and superior fatigue life. The increased EPI of the inner ply for Example 11 increases the maximum load, circumferential tensile modulus and IPSM compared to Example 10.

Examples 12-15

Using stitching, the effect of simple introduction of the three-dimensional reinforcement into Example 1 was studied. Examples 12-14 were stitched across the entire surface of the composite using starting PEN code 5, the same cord used to reinforce rubber. Example 15 was stitched using a PEN cord with a 1000/2, 7 × 7 cord structure and 2400 actual deniers. All the above examples were stitched at 3 rows per inch and the stitches were 45 ° with respect to the circumferential axis of the belt. Example 12 used a continuous chain stitch similar to that of FIG. Example 13 used a cross stitch similar to that of FIG. 6. Examples 14 and 15 used a zigzag stitch similar to that in FIG. The stitched laminate was then cured under 100 psi pressure at 150 ° C. for 30 minutes. The various forms of stitching have been tested. Data for the stitched composite samples are shown in Table 4.

The data of Comparative Example 8 and Example 1 are again shown in Table 4 for comparison, respectively. In Table 4, n.s means not stitched.

As the data in Table 4 show, stitching of PEN-reinforced belt composites can significantly improve IPSM over that of belts made solely of PEN reinforcements in rubber sheets. For example, when using a cross stitch pattern, at least 16% improvement over PEN-reinforced Example 1, which is not stitched, can be achieved. As shown in Examples 12, 13 and 14, the stitch pattern has some influence on the level improvement of IPSS. Comparing Examples 14 and 15, it can be seen that the denier change of the stitching fibers does not affect the effect. In addition, stitched belts have been observed to reduce lamination detachment of composite plies, thereby reducing general fatigue related problems with tire belts of conventional designs. Lamination detachment is advantageous because it is a general breaking mechanism of tire belts.

Examples 16-19

Folding of the belt rim as a three-dimensional reinforcement was tested by introducing folding into the same two-ply belt as in Examples 3 and 4 to avoid cutting the reinforcement cord. The folded two-ply belts obtained were Examples 16 and 17. The 4-ply folded belt structure was also tested in Example 18. Example 19 is a 2-ply in which folding is introduced by braiding.

In the folded belt, the reinforcing cord of the composite was not cut during the belt manufacturing process. The structure was obtained by performing a unique series of folding operations on a unidirectional fiber reinforced rubber sheet. The folding operation is as shown in part in FIG. In the case of a braided belt, the 2-plies were braided together to form a tubular sleeve. The sleeve was compressed to produce two essentially parallel plies parallel to the vertical axis of the tubular sleeve.

Table 5 summarizes the belt structure, and mechanical and fatigue data are in Table 6. Examples 3 and 4 were also tested for the additional properties listed in Table 6. Comparative Example B is also shown in Tables 5 and 6 for each comparison. In Table 6, n.d. means 'not measured'.

The data in Table 6 show the effect of the continuous rim belt composite on the mechanical and fatigue properties. Examples 3 and 16 were identical in construction but different in structure: Example 3 had reinforcing fibers cut with cut edges, while Example 16 had non-cut edges and continuous reinforcing fibers . As shown in Table 6, the tensile strength and tensile modulus dramatically increased in the non-cut edge composite (Example 16) compared to the cut edge composite (Example 3). In Example 16, the fatigue resistance that did not break during the flexural fatigue test was dramatically higher than in Example 3. Similarly, Example 17 and Example 4 were identical in constituent material but different in structure. Once again, the beneficial effects of the non-cut edges and continuous fiber reinforcements were evident by comparing the values of tensile modulus, tensile strength and flex fatigue life in the two examples. One of the obvious reasons for the improved tensile strength and fatigue durability characteristics exhibited by the non-cut edge composite is that their breaking mechanism is fiber cutting rather than shearing failure: the non-cut edge composite of the present invention is broken by cutting of the reinforcement. On the other hand, the corresponding cut edge composite is broken by the matrix shear without cutting the reinforcing cord.

In Example 18, a sheet of 14 EPI unidirectional fiber-reinforced rubber was placed directly on the second sheet of the same unidirectional fiber reinforced rubber, followed by a ply angle of 30 [deg.] During one folding operation as in FIG. It is treated as a unit. The final result is 28 EPI in the fly angle direction (+ or-), respectively, as opposed to 21 EPI in the fly angle direction respectively in Examples 16 and 17. In Example 18 above, the IPSM was increased and the tensile modulus, tensile strength and flexural modulus were also increased as compared to Example 17 with only 21 EPI in each ply angular direction and 30 ° ply angle.

Example 19 is a braided structure, similar to Example 17, which is a 2-ply composite having 21 EPI per ply of starting PEN code 5 and a ply angle of 30 °. This improved in terms of tensile modulus and maximum load compared to Example 17 and Steel-Reinforced Comparative Example B, and had an improved fatigue life compared to Comparative Example B. However, the IPSM of Example 19 was not improved over that of Example 17.

Tensile and shear properties vary with reinforcement cord ply angles. This is shown, for example, in Table 2 and FIG. 9 for a 2-ply composite. In general, as the ply angle increases between 0 ° and 45 °, the tensile modulus decreases while the in-plane shear modulus increases. As a result, the ply angle in the existing cut rim steel belt had a typical value of 23 ° to balance the opposing changes. The cut rim belt, reinforced with nonmetallic multifilament fibers of Example 3, nearly satisfied the tensile and in-plane coefficients of the steel belt at ply angle 26 °. Increasing the ply angle to about 30 ° in Example 4 increased the in-plane shear modulus but resulted in a drop in the tensile modulus to a lower level. Through the use of the non-cut edge composite structure as in Examples 16 and 17, the bias angle could be increased to 30 ° to improve the in-plane shear modulus while at the same time exceeding the steel belt tensile coefficient of Comparative Example B. Thus, through the use of an uncut edge continuous fiber composite, formed by folding a single direction synthetic organic fiber-reinforced rubber sheet, a belt composite having a high bias angle to achieve desirable high in-plane shear modulus and more appropriate tensile properties Can be prepared. In addition, the above embodiments achieve very good flex fatigue resistance compared to existing steel-reinforced belt designs (Comparative Example B).

Embodiments of the present invention provide a weight reduction of the tire belts as compared to existing steel-reinforced belts, providing an additional advantage as well as an opportunity to reduce the weight of the entire tire. In Table 7, representative data of the weight loss are provided.

Claims (28)

A fiber-reinforced article comprising two or more plies, each said ply comprising a cord made from (a) rubber and (b) melt-spun non-metallic multifilament fibers, the cord having a twist coefficient of about 375 or less, A fiber-reinforced article, characterized in that it has a stress at an elongation of at least 1 gram / denier, an initial compression coefficient of at least about 7 grams / denier, and the at least two plies have a fiber orientation angle of at least about 23 °. The article of claim 1, wherein the twist coefficient is about 310 or less. 2. The product of claim 1, wherein the initial compression coefficient is at least 9 grams / denier. The method according to claim 1, wherein said fiber orientation angle of said at least two plies is at least 26 degrees. The article of claim 1, wherein the article comprises three plies, wherein the two plies have a fiber orientation angle of about 30 ° and the third ply has a fiber orientation angle of about 0 °. 6. The article of claim 5 wherein the third ply has the cord at 4 to 20 ends per inch. The method of claim 1, wherein the article comprises four plies, wherein the two plies have the fiber orientation angle of about 23 ° and the two plies have a fiber orientation angle of about 45 °. 8. The article of claim 7, wherein said two inner plies have said cord at 4 to 20 ends per inch. The article of claim 1 wherein said cord is made of polyethylene naphthalate. The article of claim 1 having a three-dimensional fiber reinforcement. The article of claim 10, wherein the three-dimensional reinforcement comprises stitching or folding. 12. The article of claim 11 wherein the stitches comprise a continuous chain, zigzag or cross-stitch. 12. The product of claim 11, wherein the folds form a longitudinal edge of the composite. 12. The article of claim 11, wherein the three dimensions are formed by braiding. The article of claim 1, wherein the article is substantially free of cut cord ends along its longitudinal rim. The article of claim 1, wherein the cord further comprises a cord having at least about 2 denier / filaments. The article of claim 1, wherein the cord further comprises a cord having an initial elongation coefficient of at least about 165 grams / denier. The article of claim 1, wherein the article has an in-plane shear modulus of at least about 730 pound-forces per inch. The article of claim 1, wherein the article has an in-plane shear modulus of at least about 830 pound-force per inch. The article of claim 1, wherein the article has a fatigue of at least about 2700 revolutions to failure. The article of claim 1, wherein the article has a fatigue of at least about 5500 revolutions until fracture. 2. The product of claim 1, wherein the product is a tire belt. A tire comprising the belt according to claim 1. A tire comprising the belt according to claim 9. A method of making a tire comprising incorporating therein the fiber-reinforced product of claim 1. 14. A method of making the product of claim 13, comprising helically folding a unidirectional composite sheet (79) to produce a composite having a continuous fiber reinforcement and an uncut folded edge. In a method of forming an annular object, the product of claim 13 is folded to form a ring, the ends 107 and 109 of the product are overlapped, and one of the ends has a notch 111, and And having a complementary flap (113) on the other side, folding the flap toward the notch, wherein the annular object does not have a cord end cut along its circumferential edge. 13. The method of making a product of claim 12 comprising stitching the two or more plies together.