Hollow polyester impregnated cord fabric as well as preparation process and application thereof

Abstract

The invention belongs to the field of tire framework materials, and particularly relates to a hollow polyester impregnated cord fabric as well as a preparation process and application thereof. The light-weight polyester impregnated cord fabric comprises a plurality of warp yarns and a plurality of weft yarns, the warp yarns are obtained by twisting 1-3 polyester protofilaments; the polyester protofilament is synthesized by 100-500 monofilaments; the middle of the monofilament is hollow and is a hollow filament; the degree of hollowness of the monofilament is 10-34%; the monofilament is in a quartered arc shape. Compared with a gum dipping cord thread with the same diameter size, the gum dipping cord fabric produced by using the hollow filaments with the hollowness degree of 10-34% has the advantages that the weight can be reduced by 5-20%, the purpose of light weight is achieved, meanwhile, the purchase cost can be reduced by 5-20%, and the market competitiveness of the product can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of tire skeleton materials, and in particular relates to a hollow polyester dipped cord fabric and a preparation process and application thereof. Background Art

[0002] In recent years, the global new energy vehicle market has developed rapidly. In 2023, China's new energy vehicle market grew rapidly, with sales of 9.495 million vehicles and a market share of 31.6%, a year-on-year increase of 37.9%. In order to save electricity and increase the driving range, new energy vehicles have put forward higher requirements for reducing the rolling resistance of tires. Reducing the weight of tires can meet the needs of ultra-low rolling resistance tire product development. The existing technology does not disclose the method of reducing the weight of tires by reducing the weight of polyester cord fabrics.

[0003] In the process of lightweight development and design of traditional tires, low-denier polyester cords are generally used to replace high-denier polyester cords while increasing the warp density to meet the strength requirements per unit area during the tire design process. However, this method reduces the cord diameter and cord thickness, so the entire tire needs to be redesigned, and the calendering process during the tire manufacturing process needs to be adjusted. The design process requires a large investment and the process is relatively cumbersome, so the lightweight process of skeleton materials is still relatively slow. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a preparation process and application of a hollow polyester dipped cord fabric, which reduces the weight of the tire carcass skeleton material without changing the cord diameter and thickness and without changing the tire design and calendering process, thereby reducing the weight of the tire, thereby reducing the tire rolling resistance, improving fuel utilization, reducing automobile exhaust emissions, and realizing the development of tires towards lightweight.

[0005] In order to achieve the above object, the first aspect of the present invention adopts the following technical solution:

[0006] A hollow polyester dipped cord fabric comprises warp yarns; the warp yarns are obtained by twisting 1 to 3 polyester raw yarns; the polyester raw yarns of the warp yarns are synthesized from 100 to 500 monofilaments; the polyester monofilaments are in a hollow quarter-circle arc shape.

[0007] Preferably, the hollowness of the monofilament is 10 to 34%.

[0008] Furthermore, the polyester raw yarn specification is 840-1750D.

[0009] Preferably, the number of warp yarns is 1000-1500.

[0010] Further, the hollow polyester dipped cord fabric also includes weft yarns. This is prior art and will not be described in detail.

[0011] The second aspect of the present invention provides the use of the aforementioned hollow polyester dipped cord as a tire skeleton material.

[0012] The third aspect of the present invention adopts the following technical solution: a preparation process of hollow polyester dipped tire cord fabric, comprising the following steps:

[0013] 1) Solid phase polymerization: wet polyester chips are used as raw materials, preheated, and the solid phase polymerization reaction time is ≥50h. The viscosity of the produced polyester chips reaches 1.12-1.20dl / g;

[0014] 2) Spinning;

[0015] 3) Twisting: Twisting the high-strength hollow high-modulus low-shrinkage polyester raw yarn on a direct twisting machine;

[0016] 4) Weaving: The twisted double-twisted yarn is put on the loom for weaving;

[0017] 5) Dipping in glue to obtain lightweight polyester dipped cord fabric;

[0018] In the spinning step, due to the thin wall of the hollow fiber, the hollow fiber cools faster than the conventional raw fiber (solid) under the same cooling device, and the hollow fiber bundle drops from 300°C to about 70°C (the conventional raw fiber drops from 300°C to about 100°C), which is lower than the glass transition temperature of polyester at about 75°C. At a higher stretching ratio, the hollow fiber will have a small elongation at break and poor spinnability. In order to achieve the same cooling effect for the hollow fiber and the conventional raw fiber, a new slow cooling device is designed for spinning. The length of the new slow cooling device is 200-500mm (the length of the conventional slow cooling device is 50-100mm), so that the temperature of the hollow fiber bundle after cooling reaches about 100°C, and the elongation at break is close to that of the conventional raw fiber.

[0019] The spinning speed is 5800-6500 m / min, the total stretching ratio is 1.9-2.3, and the relaxation rate is 2.0%-4.0%. A quarter-circular arc spinneret (i.e., a spinneret with four concentric circular arc-shaped spinnerets) is used to produce quarter-circular arc hollow fibers with a hollow middle, and the hollowness of the single fiber is 10-34% (more preferably 10-26%). The hollow high modulus low shrinkage polyester precursor is composed of 100-500 single fibers, and the precursor specification is 840D-1750D.

[0020] Preferably, the high-strength hollow high-modulus low-shrinkage polyester raw yarn has a strength of ≥7.8 cN / dtex.

[0021] Preferably, the outer diameter of the spinneret hole is Φ1.5-Φ2.0 mm, the inner diameter is Φ1.1-Φ1.4 mm, the slit width is 0.10-0.18 mm, the hole depth is 0.5-1.0 mm, and the spinning assembly pressure (i.e., the spinneret assembly pressure) is 10-20 MPa.

[0022] Preferably, the warp yarn is obtained by twisting 1 to 3 polyester raw yarns.

[0023] The present invention protects hollow polyester dipped cord fabric with specifications of 840D / 2 to 1750D / 2 and its preparation process. The preparation process specifically includes the following steps (spinning speed, relaxation rate, stretching ratio, etc. are more important):

[0024] (1) Solid phase polymerization: Wet slices are used as raw materials, and high temperature and high air volume (temperature>211°C, air volume>6800m 3 / h) solid polymerization process conditions to preheat, so that the low molecular terminal hydroxyl and carboxyl groups of the polyester are fully activated. At the same time, the existing solid phase polymerization is modified to add a second-stage reactor and extend the reaction time to ≥50h. The viscosity of the produced chips reaches high viscosity PET chips between 1.12-1.20dl / g.

[0025] (2) Spinning:

[0026] Melting process: High-viscosity sliced ​​raw materials are heated and melted in the range of 280℃~330℃ under N2 protection, and then enter the spinning box. The temperature of the spinning box is controlled at 280℃~310℃; the cooling temperature is 40-70℃, the slow cooling device is 200-500mm, the spinning speed reaches 5800m / min~6500m / min, the total stretching ratio is 1.9~2.3, and the relaxation rate is 2.0%~4.0%. At the same time, a specially customized hollow spinneret is used to produce high-strength hollow high-modulus low-shrinkage raw yarn with a hollowness of 10~34%, and the strength can reach: strength ≥7.8cN / dtex.

[0027] The cross section of the polyester precursor is a hollow quarter arc type, the cross section of the spinneret hole is a four-petal concentric arc type (i.e., a quarter arc type), the outer diameter of the spinneret hole is Φ1.5-Φ2.0mm, the inner diameter is Φ1.1-Φ1.4mm, the slit width is 0.10-0.18mm, the aperture depth is 0.5-1.0mm, and the assembly pressure is 10-20Mpa. With such a spinneret hole outer diameter and inner diameter, the hollowness of the monofilament is moderate; with such a slit width, the slit width is not too thin, and the slit width plays a supporting role of the spinneret hole. Too thinness will cause the spinneret hole diameter to deform and the monofilament cross section to be non-circular; the slit width is not too thick, and too thick will cause the wall thickness of the formed monofilament to be uneven. With such an aperture depth, the assembly pressure is moderate. If the assembly pressure is too low, the spinning will be discontinuous and the spinnability will be poor. If the assembly pressure is too high, the fiber will be squeezed and deformed, affecting the tensile strength and ductility of the tow, thereby affecting the uniformity and strength of the precursor.

[0028] (3) Twisting:

[0029] The high-strength hollow high-modulus low-shrinkage polyester raw yarn is twisted on a direct twisting machine, with a spindle speed of 8500-9000 rpm, an external tension of 10-20%, an internal tension of 25-45%, and an overfeed ratio of -2.0--1.5%;

[0030] (4) Weaving:

[0031] The twisted double-twisted yarn is woven on the air jet loom at a speed of 550 to 750 revolutions per minute according to the required warp density, width and piece length;

[0032] (5) Dipping process

[0033] The conditions for one-bath dipping are: the dipping solution is mainly blocked isocyanate and epoxy resin, with a solid content of 3.8%, a drying temperature of 155-165°C, a tension of 1000-1500 daN; a drawing temperature of 235-245°C, a tension of 2000-3500 daN; and a speed of 75-85 m / min.

[0034] The conditions for the two-bath dipping treatment are: the two-bath dipping solution is mainly RFL, with a solid content of 24.1%, a drying temperature of 155-165°C, a tension of 1000-1500 daN; a setting temperature of 235-245°C, a tension of 900-1100 daN; and a speed of 75-85 m / min.

[0035] Design a dipping process with a high-temperature drawing zone temperature of 235-245°C and a drawing tension of >2000daN. By adjusting the drawing / retraction ratio to the optimal range of 2.0-2.5%, design a tight hot drawing dipping process and a suitable dipping formula system to fully improve the strength retention rate of the cord and make the dipped cord fabric meet the high strength requirements.

[0036] The beneficial effects of the present invention are as follows: the hollow polyester dipped tire cord of the present invention reduces the weight of the tire carcass skeleton material without changing the cord diameter and thickness and without changing the tire design and calendering process, thereby reducing the weight of the tire, thereby reducing the tire rolling resistance, improving fuel utilization, reducing automobile exhaust emissions, and realizing the development of the tire towards lightweight.

[0037] A hollow polyester industrial filament is prepared, which is lighter than traditional polyester industrial filament. By greatly improving the spinning speed and drawing ratio and other parameters in the production process, it is ensured that it has high strength (≥140N), smaller elongation and dry heat shrinkage (≤2.0%), and is used to replace conventional polyester cord products to achieve the effect of reducing costs and making tires lighter.

[0038] The present invention uses a dipped cord fabric produced by hollow fibers with a hollowness of 10 to 34%. Compared with dipped cords with the same diameter, the weight can be reduced by 5 to 20%, achieving the purpose of lightweighting. The procurement cost can be reduced by 5 to 20%, which can greatly improve the market competitiveness of the product.

[0039] Compared with similar hollow polyester filament products, the advantages of the quarter-arc hollow yarn proposed by the present invention are as follows: 1. The quarter-arc hollow yarn has better spinnability than the three-arc hollow yarn. The shape and surface characteristics of the fiber monofilament make the spinning process smoother and can adapt to different types of spinning processes, ensuring that there will not be too many hairy yarns, broken yarns and other problems during the spinning process.

[0040] 2. The hollowness of the quarter-arc hollow fiber is greater than that of the three-arc hollow fiber under the same specification, that is, the same hollowness can be achieved by using a smaller raw fiber specification, which is more conducive to reducing the consumption of raw materials. If the hollowness of the six-arc hollow fiber under the same specification is too large, the fiber wall will become thinner, and the fiber will become easier to squeeze and flatten. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a cross-sectional view of the hollow polyester dipped cord prepared in Example 1 after being magnified 500 times;

[0042] Figure 2 The cross-sectional view after 500 times magnification is compared between the conventional polyester dipped cord prepared in Comparative Example 1 (left) and the hollow polyester dipped cord prepared in Example 1 (right);

[0043] Figure 3 is a cross-sectional view of a spinneret hole of a spinneret;

[0044] Figure 4 It is a structural schematic diagram of a slow cooling device;

[0045] Figure 5These are cross-sectional views of a quarter-arc-shaped hollow fiber and a three-arc-shaped hollow fiber; cross-sectional view of a quarter-arc-shaped hollow fiber (left), cross-sectional view of a three-arc-shaped hollow fiber (right). DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0047] Unless otherwise specified, the test materials or reagents used in the following examples are all existing and can be obtained from commercial channels. If no specific techniques or conditions are specified in the examples, they can be carried out according to conventional techniques or conditions disclosed in the art.

[0048] The specific production process and process parameters of Examples 1-4 are as follows, wherein the same-size precursor yarn specifically means that the outer diameter of the single yarn is the same as that of the hollow precursor yarn, and the number of single yarns of the precursor yarn is the same as that of the hollow yarn.

[0049] 1) Solid phase polymerization

[0050] Solid phase polymerization: using wet slices as raw materials, high temperature and large air volume (temperature> 211°C, air volume> 6800m 3 / h) solid polymerization process conditions to preheat the polyester to fully activate the low molecular terminal hydroxyl and carboxyl groups. At the same time, the existing solid phase polymerization is modified to add a second-stage reactor (so that the polyester chips are reacted in the first-stage solid phase polymerization reactor and the second-stage solid phase polymerization reactor in turn), and the reaction time is extended to ≥50h, and the molecular weight is further increased and more uniform. See Table 1 for details. After preheating and solid phase viscosity enhancement in the continuous solid phase viscosity enhancement device, the intrinsic viscosity of the PET chips after treatment is 1.12-1.20dl / g, as shown in Table 1 for details.

[0051] Table 1 Solid phase polymerization process of hollow fibers and original fibers of the same size

[0052]

[0053] The same-sized precursors in this article have the same preparation process as the corresponding hollow fibers, except for the spinneret hole shape and the specific parameters mentioned in the table.

[0054] 2) Spinning process

[0055] Melting process: High-viscosity sliced ​​raw materials are heated and melted at 305°C under N2 protection, and then enter the spinning box. The temperature of the spinning box is controlled at 300°C; the slow cooling device is 300mm long, and a certain spinning speed, total stretching ratio and relaxation rate are set; the annular air cooling temperature is 50°C. When producing hollow fibers, a specially customized hollow spinneret is used to produce high-strength hollow high-modulus low-shrinkage polyester precursor fibers with a certain hollowness. The hollow precursor fiber index can reach: strength ≥7.8cN / dtex. See Table 2-4 for details.

[0056] Table 2 Spinning process and raw yarn index

[0057]

[0058] Among them, the hollow polyester raw fiber has the shape of Figure 1 As shown, the cross-sectional shape of the spinneret hole is Figure 3 shown.

[0059] Table 3 Specifications and shapes of hollow spinneret and raw yarn

[0060]

[0061]

[0062] Table 4 Comparison of hollow fiber performance of new slow cooler

[0063]

[0064] The slow cooling device (new slow cooler) includes: an outer shell 1, an inner shell 2, a heating layer 3, a heat-insulating layer 4, a first connecting mechanism 5 and a second connecting mechanism 6; the heat-insulating layer is closely attached to the outside of the heating layer; the first connecting mechanism 5 is connected to the spinneret; the second connecting mechanism 6 is connected to the heat-insulating cylinder. The filaments ejected from the spinneret pass through the inside of the slow cooling device. 3-6 layers of different heating temperatures are set from top to bottom in the slow cooling device. The temperature of the heating layer is 260-340℃ and gradually decreases from top to bottom. The length of each layer is 40-100mm. The air temperature in the slow cooling device is slightly lower than the temperature of the heating layer.

[0065] For example, in Examples 1-4, four layers of different heating temperatures are set from top to bottom in the new slow cooling device, each layer is 75 mm long, and the temperatures of each heating layer are 330°C, 310°C, 290°C, and 270°C, respectively.

[0066] The original slow cooler length in Table 4 is 75 mm and the heating layer temperature is 330°C.

[0067] In this paper, except for Table 4 involving the original slow cooling device, the rest are polyester yarns prepared by the new slow cooling device.

[0068] Table 5 Comparison of raw silk properties

[0069]

[0070] In all embodiments, twisting: two high-strength hollow high-modulus low-shrinkage polyester raw yarns are twisted on a direct twisting machine with a spindle speed of 8800 rpm, an external tension of 15%, an internal tension of 35%, and an overfeed ratio of -1.5%; weaving: the twisted double-twisted yarn is woven on an air-jet loom at a speed of 650 rpm according to the required warp density, width and piece length.

[0071] 3) Dipping

[0072] In all embodiments, the conditions of one-bath dipping are: the dipping solution is mainly blocked isocyanate and epoxy resin, solid content is 3.8%, drying temperature is 160°C, tension is 1200daN; drawing speed is 80 m / min; the conditions of two-bath dipping treatment are: the two-bath dipping solution is mainly RFL, solid content is 24.1%, drying temperature is 160°C, tension is 1200daN; setting temperature is 240°C, tension is 1000daN; speed is 80 m / min), which fully improves the strength retention rate of the cord and makes the dipped cord fabric meet the high strength requirements. See Table 6 for details.

[0073] Table 6 Dipping process parameters

[0074]

[0075]

[0076] In the above Example 1, the 840D / 2 hollow dipped polyester cord made of 840D hollow fibers (hollowness of 34%) has no significant difference in physical properties compared with the conventional 1000D / 2 dipped polyester cord (Table 7), but after weight measurement, its weight is reduced by 18.5% compared with the normal polyester cord of the same specification.

[0077] Table 7 Main characteristics of 840D / 2 hollow polyester dipped cord fabric

[0078]

[0079] In the above Example 2, the physical properties of the 1100D / 2 hollow dipped polyester cord made of 1100D hollow fibers (hollowness of 25%) are not significantly different from those of the conventional 1300D / 2 dipped polyester cord (Table 8), but after weight measurement, its weight is reduced by 15.3% compared with the normal polyester cord of the same specification.

[0080] Table 8 Main characteristics of 1100D / 2 hollow polyester dipped cord fabric

[0081]

[0082] According to the preparation process of the hollow fiber in Example 1, the spinneret is replaced with a spinneret with a spinneret hole in a three-point arc shape, and the prepared hollow fiber is as follows Figure 5 shown.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A hollow polyester dipped cord fabric, characterized in that: Including warp yarn; the warp yarn is obtained by twisting 1 to 3 polyester raw yarns; the polyester raw yarn of the warp yarn is synthesized from 100 to 500 monofilaments; the polyester monofilament is in a hollow quarter-circular arc shape.

2. The hollow polyester dipped cord fabric according to claim 1, characterized in that: The hollowness of the monofilament is 10~34%.

3. The hollow polyester dipped cord fabric according to claim 1, characterized in that: The specifications of polyester raw yarn are 840-1750D.

4. The hollow polyester dipped cord fabric according to claim 1, characterized in that: The number of warp yarns is 1000-1500.

5. The hollow polyester dipped cord fabric according to claim 1, characterized in that: Also includes weft yarn.

6. Use of the hollow polyester dipped cord fabric according to any one of claims 1 to 5 as a tire skeleton material.

7. A process for preparing hollow polyester dipped tire cord fabric, characterized in that: The steps include: 1) Solid phase polymerization: using wet polyester chips as raw materials, preheating, solid phase polymerization reaction time ≥ 50h; 2) Spinning; 3) Twisting: Twisting the high-strength hollow high-modulus low-shrinkage polyester raw yarn on a direct twisting machine to prepare a double-twisted yarn; 4) Weaving: The twisted double-twisted yarn is put on the loom for weaving; 5) Dipping in glue to obtain hollow polyester dipped cord fabric; In the spinning step, a slow cooling device is used, the length of the slow cooling device is 200-500mm, the spinning speed is 5800-6500m / min, the total stretching ratio is 1.9-2.3, and the relaxation rate is 2.0%-4.0%; a spinneret with a four-petal concentric arc spinneret hole is used to produce a quarter-arc hollow monofilament, the hollowness of the monofilament is 10-26%, the hollow high modulus low shrinkage polyester precursor is composed of 100-500 monofilaments, and the specification of the polyester precursor is 840D-1750D.

8. The process for preparing hollow polyester dipped tire cord fabric according to claim 7, characterized in that: The strength of high-strength hollow high-modulus low-shrinkage polyester raw yarn is ≥7.8 cN / dtex.

9. The process for preparing hollow polyester dipped tire cord fabric according to claim 7, characterized in that: The outer diameter of the spinneret hole is Φ1.5~Φ2.0 mm, the inner diameter is Φ1.1~Φ1.4 mm, the slit width is 0.10~0.18 mm; the hole depth is 0.5~1.0 mm, and the component pressure is 10-20Mpa.

10. The process for preparing hollow polyester dipped tire cord fabric according to claim 7, characterized in that: In the twisting step, the multi-twisted yarn is obtained by twisting 1 to 3 polyester raw yarns.

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