Polyester demolding cloth for polyurethane forming process

Abstract

The utility model relates to the technical field of release cloth, in particular to polyester release cloth for a polyurethane forming process. The polyester demolding cloth for the polyurethane forming process is a plain weave structure, the warp density is 180-200 pieces / 10cm, and the weft density is 170-190 pieces / 10cm; warps in the polyester demolding cloth comprise first core-spun yarns, each first core-spun yarn is formed by twisting a plurality of first core-spun monofilaments, and each first core-spun monofilament comprises a first core layer and a first polyester skin layer; wefts in the polyester demolding cloth comprise second core-spun yarns, each second core-spun yarn is formed by twisting a plurality of second core-spun monofilaments, and each second core-spun monofilament comprises a second core layer and a second polyester skin layer. The polyester demolding cloth can be used for a polyurethane forming process, the surface roughness uniformity of a workpiece can be guaranteed, the demolding performance is good, the polyester demolding cloth is free of residues after being torn off, the recycled polyester demolding cloth can be recycled for the second time, and the production cost for producing blades through the polyurethane forming process is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of release fabrics, and in particular to a polyester release fabric for polyurethane molding processes. Background Art

[0002] Blades are one of the most fundamental and costliest components of wind turbines. Since 2010, the product iteration speed has increased sharply, and the prices of wind turbines have decreased in a fluctuating manner. Epoxy resin is usually required in the blade production process. However, in recent years, the price of the raw material epoxy resin has shown an upward trend, resulting in a year-on-year increase in the production cost of blades. Therefore, under the dual pressures from upstream and downstream, it has become an inevitable trend for blade manufacturers to promote more economical alternative materials to epoxy resin. Compared with epoxy resin glue, polyurethane potting glue has the advantages of low price, low viscosity, good wettability, low exothermic peak, stronger fluidity and mechanical properties of products. At the same time, it has more excellent tensile properties, bending properties and compression modulus, making it one of the ideal alternative materials for epoxy resin systems. Currently, some domestic blade manufacturers have begun to try using polyurethane-based blades, such as Sany Heavy Industry Co., Ltd.

[0003] Due to its unique chemical structure, polyurethane resin contains a large number of isocyanate groups. The isocyanate groups will react chemically with the hydroxyl groups in water molecules to generate bubbles, ultimately leading to a decrease in the mechanical properties of the material. Therefore, when using polyurethane resin glue to replace epoxy resin glue, moisture isolation treatment is required.

[0004] In the vacuum infusion RTM process of epoxy resin glue, traditional nylon release fabrics are used. However, when traditional nylon release fabrics are used in the vacuum infusion RTM process of polyurethane resin glue, surface quality problems will occur. The reason is that the isocyanate groups in polyurethane resin glue will react with the moisture adsorbed on the surface of nylon to generate bubbles, resulting in a decrease in the mechanical properties of the blades or pultruded beams formed by polyurethane resin, and the surface roughness after demolding is uneven, and local bubble defects are likely to occur. During the process of tearing off the release fabric, the reaction bonding force between the release fabric and polyurethane resin glue is relatively strong, resulting in relatively difficult demolding. During the tearing process of the release fabric, it will leave residues in a torn state, which not only affects the surface quality of the material, but also affects the secondary utilization of the release fabric. Therefore, the inventor provides a polyester release fabric for polyurethane molding processes that is easy to demold and can be reused. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a polyester release fabric for polyurethane molding processes.

[0006] The polyester release fabric for polyurethane molding processes provided by the present application is achieved through the following technical solutions:

[0007] A polyester release fabric for a polyurethane molding process has a plain weave structure. The warp density of the polyester release fabric is 180 - 200 ends per 10 cm, and the weft density of the polyester release fabric is 170 - 190 ends per 10 cm. The warp yarns in the polyester release fabric include first core-spun yarns, and each first core-spun yarn is twisted by a number of first core-spun filaments. Each first core-spun filament includes a first core layer and a first polyester skin layer, and the first polyester skin layer covers the outer peripheral side of the first core layer. The weft yarns in the polyester release fabric include second core-spun yarns, and each second core-spun yarn is twisted by a number of second core-spun filaments. Each second core-spun filament includes a second core layer and a second polyester skin layer, and the second polyester skin layer covers the outer peripheral side of the second core layer.

[0008] The polyester release fabric in this application can be used in the polyurethane molding process. It can not only ensure the uniformity of the surface roughness of the workpiece, but also has good demolding performance. The polyester release fabric can be torn off without residue, and the recycled polyester release fabric can be recycled for a second time, reducing the production cost of producing blades by the polyurethane molding process.

[0009] Preferably, each first core-spun yarn is twisted by 48 - 64 first core-spun filaments, and the specification of each first core-spun yarn is 70 - 150 D. Each second core-spun yarn is twisted by 36 - 54 second core-spun filaments, and the specification of each second core-spun yarn is 70 - 135 D.

[0010] Preferably, in each first core-spun filament, the first core layer is nylon 66, and the first polyester skin layer is polyester. The outer diameter of the first polyester skin layer is 1.2 - 1.5 times the diameter of the first core layer.

[0011] Preferably, in each second core-spun filament, the second core layer is nylon 66, and the second polyester skin layer is polyester. The outer diameter of the second polyester skin layer is 1.2 - 1.5 times the diameter of the second core layer.

[0012] Preferably, each first core-spun yarn is twisted by 64 first core-spun filaments, and the specification of each first core-spun yarn is 135 D. Each second core-spun yarn is twisted by 48 second core-spun filaments, and the specification of each second core-spun yarn is 105 D.

[0013] The warp tensile strength of the produced polyester release fabric > 1200 N, the weft tensile strength > 1100 N, and the grammage is 100 - 110 g / m 2 。

[0014] Preferably, the warp yarns in the polyester release fabric further include first reinforcing fibers, and there are 1 - 5 first core-spun yarns arranged between adjacent first reinforcing fibers. The first reinforcing fibers are UHMWPE fibers with a fineness of 144 - 200 Dtex.

[0015] Preferably, the weft of the polyester release fabric further includes a second reinforcing fiber, and there are 1-5 second core-spun yarns arranged between adjacent second reinforcing fibers; the second reinforcing fiber is a UHMWPE fiber of 144-200 Dtex.

[0016] Preferably, the outer wall of the first reinforcing fiber is coated with a first heat-resistant polyester PET layer; the thickness of the first heat-resistant polyester PET layer is 10-25 microns; the outer wall of the second reinforcing fiber is coated with a second heat-resistant polyester PET layer; the thickness of the second heat-resistant polyester PET layer is 10-25 microns.

[0017] The warp tensile strength of the polyester release fabric > 1350 N, the weft tensile strength > 1200 N, and the gram weight is 95-110 g / m 2 , which can effectively improve the overall tear resistance. The polyester release fabric can be torn off without residue, and the recycled polyester release fabric can be recycled twice, reducing the production cost of the polyurethane molding process for producing blades.

[0018] Preferably, a fluorosilicone resin layer is integrally formed on the surface of the polyester release fabric by an impregnation process.

[0019] By adopting the above technical solutions, the demoulding performance, weather resistance and tear resistance of the polyester release fabric can be further improved, and at the same time, the overall heat resistance of the polyester release fabric can also be improved.

[0020] In summary, the present application has the following advantages:

[0021] 1. The polyester release fabric in the present application can be used in the polyurethane molding process, which can not only ensure the uniformity of the surface roughness of the workpiece, but also has good demoulding performance. The polyester release fabric can be torn off without residue, and the recycled polyester release fabric can be recycled twice, reducing the production cost of the polyurethane molding process for producing blades.

[0022] 2. The production and preparation of the polyester release fabric in the present application is relatively easy, which is convenient for industrial production, reduces the use cost of the polyester release fabric, and thus reduces the total production cost of the polyurethane molding process for producing blades.

[0023] 3. Introducing UHMWPE fibers in the present application can effectively improve the overall tear resistance. The polyester release fabric can be torn off without residue, and the recycled polyester release fabric can be recycled twice, reducing the production cost of the polyurethane molding process for producing blades.

[0024] 4. Using the fluorosilicone resin layer to modify the surface of the polyester release fabric in the present application can further improve the demoulding performance, weather resistance and tear resistance of the polyester release fabric, and at the same time, the overall heat resistance of the polyester release fabric can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the polyester release cloth in the embodiment of the present application.

[0026] Figure 2 It is a schematic structural diagram of the first core-spun monofilament in the embodiment of the present application.

[0027] Figure 3 It is a schematic structural diagram of the second core-spun monofilament in the embodiment of the present application.

[0028] Figure 4 It is a schematic structural diagram of the polyester release cloth in the embodiment of the present application, and the warp and weft contain UHMWPE fibers.

[0029] Figure 5 It is a schematic structural diagram of the first reinforcing fiber in the embodiment of the present application.

[0030] Figure 6 It is a schematic structural diagram of the second reinforcing fiber in the embodiment of the present application.

[0031] In the figure, 1 is the first core-spun yarn; 100 is the fluorosilicone resin layer; 10 is the first core-spun monofilament; 11 is the first core-spun monofilament; 12 is the first polyester skin layer; 2 is the second core-spun yarn; 20 is the second core-spun monofilament; 21 is the second core layer; 22 is the second polyester skin layer; 3 is the first reinforcing fiber; 30 is the first heat-resistant polyester PET layer; 4 is the second reinforcing fiber; 40 is the second heat-resistant polyester PET layer. Detailed implementation manners

[0032] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with examples and comparative examples. Examples

[0033] A polyester release cloth for polyurethane molding process is in plain weave. The warp density of the polyester release cloth is 180 - 200 threads / 10 cm, and the weft density of the polyester release cloth is 170 - 190 threads / 10 cm.

[0034] Reference Figure 1 , the warp in the polyester release cloth includes the first core-spun yarn 1, and the first core-spun yarn 1 is twisted by a plurality of first core-spun monofilaments 10. Specifically, the first core-spun yarn 1 is twisted by 48 - 64 first core-spun monofilaments 10, with a twist of 445, and the specification of the first core-spun monofilament 10 is 1 - 2D. The specification of the first core-spun yarn 1 is 70 - 150D, customized by Weifang Jinyi Yarn Co., Ltd.

[0035] Reference Figure 1, the first core-spun monofilament 10 includes a first core layer 11 and a first polyester skin layer 12. The first polyester skin layer 12 is coated on the outer peripheral side of the first core layer 11, which can reduce the water absorption rate of the first core layer 11, thereby improving the overall quality stability of the polyester release fabric. In the first core-spun monofilament 10, the first core layer 11 is nylon 66 and the first polyester skin layer 12 is polyester; the outer diameter of the first polyester skin layer 12 is 1.2 - 1.5 times the diameter of the first core layer 11. The first core-spun yarn 1 customized by Weifang Jinyi Yarn Co., Ltd. is a polyester / urethane core-spun yarn with polyester as the skin layer and urethane as the core layer, with a specification of 135D / 64F, and the outer diameter of the polyester is 1.5 times the diameter of the urethane.

[0036] Reference Figure 1 , the weft in the polyester release fabric includes a second core-spun yarn 2. The second core-spun yarn 2 is twisted by a number of second core-spun monofilaments 20. Preferably, the second core-spun yarn 2 is twisted by 36 - 54 second core-spun monofilaments 20. The specification of the second core-spun monofilament 20 is 1 - 2D, with a twist of 445, and the specification of the second core-spun yarn 2 is 70 - 135D, customized by Weifang Jinyi Yarn Co., Ltd.

[0037] Reference Figure 1 , the second core-spun monofilament 20 includes a second core layer 21 and a second polyester skin layer 22. The second polyester skin layer 22 is coated on the outer peripheral side of the second core layer 21, which can effectively reduce the water absorption rate of the second core layer 21, thereby improving the overall quality stability of the polyester release fabric. In the second core-spun monofilament 20, the second core layer 21 is nylon 66 and the second polyester skin layer 22 is polyester. The outer diameter of the second polyester skin layer 22 is 1.2 - 1.5 times the diameter of the second core layer 21. Preferably, the second core-spun yarn 2 is twisted by 48 second core-spun monofilaments 20, with a specification of 105D / 48F, customized by Weifang Jinyi Yarn Co., Ltd., a polyester / urethane core-spun yarn, and the outer diameter of the polyester is 1.5 times the diameter of the urethane.

[0038] A fluorosilicone resin layer 100 is integrally formed on the surface of the polyester release fabric by an impregnation process. The warp tensile strength of the polyester release fabric made of the above warp and weft is > 1200N, the weft tensile strength is > 1100N, and the gram weight is 100 - 110g / m 2 .

[0039] Reference Figure 3 , in order to further improve the mechanical properties of the polyester release fabric, the warp in the polyester release fabric further includes a first reinforcing fiber 3. There are 1 - 5 first core-spun yarns 1 arranged between adjacent first reinforcing fibers 3. The first reinforcing fiber 3 is a 144 - 200Dtex UHMWPE fiber, such as Spectra 2000 from Allied Corporation, with a linear density of 144Dtex, a tensile strength of 2.74GPa, a breaking strength of 41N, and a modulus of 113 / N*tex -1, elongation at break of 2.8% or Tekmilon Ι of Mitoui Company. The outer wall of the first reinforcing fiber 3 is coated with a first heat-resistant polyester PET layer 30; the first heat-resistant polyester PET layer 30 is a polyester layer, and the thickness of the polyester layer is 10 - 25 μm.

[0040] Reference Figure 4 , in order to further improve the mechanical properties of the polyester release fabric, the weft of the polyester release fabric further includes a second reinforcing fiber 4, and there are 1 - 5 second core-spun yarns 2 arranged between adjacent second reinforcing fibers 4. The second reinforcing fiber 4 is a UHMWPE fiber with a linear density of 144 - 200 Dtex, such as Spectra 2000 of Allied Company, with a linear density of 144 Dtex, a tensile strength of 2.74 GPa, a breaking strength of 41 N, and a modulus of 113 / N*tex -1 , elongation at break of 2.8% or Tekmilon Ι of Mitoui Company. The outer wall of the second reinforcing fiber 4 is coated with a second heat-resistant polyester PET layer 40; the second heat-resistant polyester PET layer 40 is a polyester layer, and the thickness of the polyester layer is 10 - 25 μm.

[0041] A fluorosilicone resin layer 100 is integrally formed on the surface of the polyester release fabric through an impregnation process. The warp tensile strength of the polyester release fabric made of the above warp and weft is > 1350 N, the weft tensile strength is > 1200 N, and the grammage is 95 - 110 g / m 2 .

[0042] Example 1: A polyester release fabric for polyurethane molding process is in a plain weave structure, the warp density of the polyester release fabric is 180 threads / 10 cm, the weft density of the polyester release fabric is 170 threads / 10 cm, and the grammage is 101.3 g / m 2 .

[0043] The warp of the polyester release fabric is the first core-spun yarn 1, and the first core-spun yarn 1 is a polyester / urethane core-spun yarn with polyester as the cortex and urethane as the core, with a specification of 135 D / 64F, customized by Weifang Jinyi Yarn Co., Ltd., and the outer diameter of the polyester is 1.5 times the diameter of the urethane.

[0044] The weft of the polyester release fabric is the second core-spun yarn 2, and the specification of the second core-spun yarn 2 is 105 D / 48F, customized by Weifang Jinyi Yarn Co., Ltd., a polyester / urethane core-spun yarn, and the outer diameter of the polyester is 1.5 times the diameter of the urethane.

[0045] A fluorosilicone resin layer 100 is integrally formed on the surface of the polyester release fabric through an impregnation process (impregnated in an aqueous solution of 3,3,3-trifluoropropyltrimethoxysilane KH-331 with a mass concentration of 5 wt% for 15 min, dried, and the impregnation and drying processes are repeated twice to complete the impregnation process to form a fluorosilicone resin layer 100 on the surface of the polyester release fabric yarn).

[0046] The difference between Example 2 and Example 1 lies in that: the warp density of the polyester release fabric is 200 threads / 10 cm, the weft density of the polyester release fabric is 180 threads / 10 cm, and the grammage is 109.7 g / m 2 .

[0047] The difference between Example 3 and Example 1 lies in that: the warp density of the polyester release fabric is 190 threads / 10 cm, the weft density of the polyester release fabric is 180 threads / 10 cm, and the grammage is 106.4 g / m 2 .

[0048] The difference between Example 4 and Example 1 lies in that: a polyester release fabric for polyurethane molding process is plain weave, the warp density of the polyester release fabric is 180 threads / 10 cm, the weft density of the polyester release fabric is 170 threads / 10 cm, and the grammage is 97.2 g / m 2 .

[0049] The warp of the polyester release fabric is the first core-spun yarn 1 and the first reinforcing fiber 3. There is 1 first core-spun yarn 1 arranged between adjacent first reinforcing fibers 3, that is, the first core-spun yarn 1 and the first reinforcing fiber 3 are arranged at intervals. The first reinforcing fiber 3 is UHMWPE fiber. The UHMWPE fiber is Spectra 2000 of Allied Corporation, with a linear density of 144 Dtex, a tensile strength of 2.74 GPa, a breaking strength of 41 N, and a modulus of 113 / N*tex -1 , and the elongation at break is 2.8%. The UHMWPE fiber is coated with a first heat-resistant polyester PET layer 30 on the outer wall. The first heat-resistant polyester PET layer 30 is a polyester layer, and the thickness of the polyester layer is 20 - 25 μm. The polyester layer coated on the UHMWPE fiber is processed and customized by Weifang Jinyi Yarn Co., Ltd.

[0050] The weft of the polyester release fabric is the second core-spun yarn 2 and UHMWPE fiber. The specification of the second core-spun yarn 2 is 105 D / 48F, customized by Weifang Jinyi Yarn Co., Ltd., a polyester / spandex core-spun yarn, and the outer diameter of the polyester is 1.5 times the diameter of the spandex

[0051] The weft of the polyester release fabric is the second core-spun yarn 2 and the second reinforcing fiber 4. There is 1 second core-spun yarn 2 arranged between adjacent second reinforcing fibers 4, that is, the second core-spun yarn 2 and the second reinforcing fiber 4 are arranged at intervals. The second reinforcing fiber 4 is UHMWPE fiber. The UHMWPE fiber is Spectra 2000 of Allied Corporation, with a linear density of 144 Dtex, a tensile strength of 2.74 GPa, a breaking strength of 41 N, and a modulus of 113 / N*tex -1, the elongation at break is 2.8%. The UHMWPE fiber is coated with a second heat-resistant polyester PET layer 40 on the outer wall. The second heat-resistant polyester PET layer 40 is the polyester layer, and the thickness of the polyester layer is 20 - 25 μm. The polyester layer coated on the UHMWPE fiber is processed and customized by Weifang Jinyi Yarn Co., Ltd.

[0052] The difference between Example 5 and Example 4 is that: the warp of the polyester release cloth is the first core-spun yarn 1 and the first reinforcing fiber 3, and there are 3 first core-spun yarns 1 arranged between adjacent first reinforcing fibers 3. The weft of the polyester release cloth is the second core-spun yarn 2 and the second reinforcing fiber 4, and there are 3 second core-spun yarns 2 arranged between adjacent second reinforcing fibers 4.

[0053] The difference between Example 6 and Example 4 is that: the warp of the polyester release cloth is the first core-spun yarn 1 and the first reinforcing fiber 3, and there are 5 first core-spun yarns 1 arranged between adjacent first reinforcing fibers 3. The weft of the polyester release cloth is the second core-spun yarn 2 and the second reinforcing fiber 4, and there are 4 second core-spun yarns 2 arranged between adjacent second reinforcing fibers 4.

[0054] The difference between Comparative Example 1 and Example 1 is that: the warp density of the polyester release cloth is 160 roots / 10 cm, the weft density of the polyester release cloth is 150 roots / 10 cm, and the gram weight is 93.6 g / m 2 。

[0055] The difference between Comparative Example 2 and Example 1 is that: the warp of the polyester release cloth is 135D spandex, Shaoxing Keqiao Pubuzhuang Knitting and Spinning Co., Ltd., and the weft of the polyester release cloth is 105D spandex, Shaoxing Keqiao Pubuzhuang Knitting and Spinning Co., Ltd.

[0056] The difference between Comparative Example 3 and Example 1 is that: the fluorosilicone resin layer is not integrally formed on the surface of the polyester release cloth by impregnation process.

[0057] Performance detection test A: 1. Test method for the gram weight of the polyester release cloth: It is measured according to the test method of GB / T 4669-2008. 2. Test method for heat resistance performance: It is measured according to the test method of GB / T 13767-1992. If the heat resistance performance is greater than 180 °C, it is recorded as qualified. 3. Test method for warp and weft density: It is measured according to the test method of GB / T 4668-1995. 4. Test method for warp tensile strength and weft tensile strength: It is measured according to the test method of GB / T 3923.1-2013.

[0058] Table 1: Test parameter table of polyester release cloth in Examples 1 - 6 and Comparative Examples 1 - 3

[0059]

[0060] Performance Detection Test B: The polyester release fabrics in Examples 1-6 and Comparative Examples 1-3 were pultruded to the same length. The pultruded composite material was glass fiber / polyurethane resin (glass fiber volume content 60%), with release fabrics covered on the upper and lower sides, and pultruded plates with a width of 120 mm were prepared. A micrometer was used to measure the shrinkage of the release fabric in the width direction; the surface of the pultruded profile was visually inspected to count the wrinkles of the release fabric; then the release fabric was peeled off, and the residual condition of the release fabric yarns and the presence of high-temperature marks were visually inspected.

[0061] Table 2: Test Parameter Table of the Application of Polyester Release Fabrics in Examples 1-6 and Comparative Examples 1-3 to Polyurethane Adhesive Encapsulation Casting

[0062]

[0063] Combined with Examples 1-3 and Comparative Examples 1-2 and combined with Tables 1-2, it can be seen that the polyester release fabric has a plain weave structure, with a warp density of 180-200 threads / 10 cm and a weft density of 170-190 threads / 10 cm, which can ensure that the polyester release fabric has good mechanical strength. When the polyester release fabric is torn off, there is no residual breakage of warp and weft threads. The recycled polyester release fabric can be recycled twice, reducing the production cost of blades in the polyurethane molding process.

[0064] Combined with Examples 1-3 and Comparative Example 3 and combined with Tables 1-2, it can be seen that the fluorosilicone resin layer on the polyester release fabric can improve the overall heat resistance performance and at the same time assist in enhancing the warp tensile strength and weft tensile strength. It can improve the demolding performance of the polyester release fabric and endow it with good mechanical strength. When the polyester release fabric is torn off, there is no residual breakage of warp and weft threads. The recycled polyester release fabric can be recycled twice, reducing the production cost of blades in the polyurethane molding process.

[0065] Combined with Examples 1-3 and Examples 4-6 and combined with Tables 1-2, it can be seen that the introduction of the first reinforcing fiber and the second reinforcing fiber can improve the polyester release fabric to have good mechanical strength. When the polyester release fabric is torn off, there is no residual breakage of warp and weft threads. The recycled polyester release fabric can be recycled twice, reducing the production cost of blades in the polyurethane molding process.

[0066] In summary, the polyester release fabric in the present application can be used in the polyurethane molding process, which can not only ensure the uniformity of the surface roughness of the workpiece, but also has good demolding performance. When the polyester release fabric is torn off, there is no residue. The recycled polyester release fabric can be recycled twice, reducing the production cost of blades in the polyurethane molding process.

[0067] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A polyester release cloth for polyurethane molding process, characterized in that: The polyester release cloth is a plain weave, the warp density of the polyester release cloth is 180-200 strands / 10 cm, and the weft density of the polyester release cloth is 170-190 strands / 10 cm; the warp threads in the polyester release cloth include a first core-spun yarn (1), the first core-spun yarn (1) is formed by twisting a plurality of first core-spun monofilaments (10), the first core-spun monofilaments (10) include a first core layer (11) and a first polyester sheath (12), the first polyester sheath (12) is coated on the outer peripheral side of the first core layer (11); the weft threads in the polyester release cloth include a second core-spun yarn (2), the second core-spun yarn (2) is formed by twisting a plurality of second core-spun monofilaments (20), the second core-spun monofilaments (20) include a second core layer (21) and a second polyester sheath (22), the second polyester sheath (22) is coated on the outer peripheral side of the second core layer (21).

2. The polyester release cloth for polyurethane molding process according to claim 1, characterized in that: The first core-spun yarn (1) is formed by twisting 48 to 64 first core-spun monofilaments (10), and the specification of the first core-spun yarn (1) is 70 to 150D; the second core-spun yarn (2) is formed by twisting 36 to 54 second core-spun monofilaments (20), and the specification of the second core-spun yarn (2) is 70 to 135D.

3. The polyester release cloth for polyurethane molding process according to claim 2, characterized in that: The first core layer (11) of the first core-covered monofilament (10) is nylon 66, and the first polyester sheath layer (12) is polyester; the outer diameter of the first polyester sheath layer (12) is 1.2-1.5 times the diameter of the first core layer (11).

4. The polyester release cloth for polyurethane molding process according to claim 3, characterized in that: The second core layer (21) of the second core-covered monofilament (20) is nylon 66, and the second polyester sheath (22) is polyester; the outer diameter of the second polyester sheath (22) is 1.2-1.5 times the diameter of the second core layer (21).

5. The polyester release cloth for polyurethane molding process according to claim 4, characterized in that: The first core-spun yarn (1) is formed by twisting 64 first core-spun monofilaments (10), and the specification of the first core-spun yarn (1) is 135D; the second core-spun yarn (2) is formed by twisting 48 second core-spun monofilaments (20), and the specification of the second core-spun yarn (2) is 105D.

6. The polyester release cloth for polyurethane molding process according to claim 5, characterized in that: The polyester release cloth has a warp tensile strength of >1200N, a weft tensile strength of >1100N, and a gram weight of 100-110g / m 2 .

7. The polyester release cloth for polyurethane molding process according to claim 6, characterized in that: The warp threads in the polyester demoulding cloth further include first reinforcing fibers (3), and 1 to 5 first core-spun yarns (1) are arranged between adjacent first reinforcing fibers (3); the first reinforcing fibers (3) are UHMWPE fibers with a Dtex of 144 to 200.

8. The polyester release cloth for polyurethane molding process according to claim 7, characterized in that: The weft yarns in the polyester demoulding cloth further include second reinforcing fibers (4), and 1 to 5 second core-spun yarns (2) are arranged between adjacent second reinforcing fibers (4); the second reinforcing fibers (4) are UHMWPE fibers with a density of 144 to 200 Dtex.

9. The polyester release cloth for polyurethane molding process according to claim 8, characterized in that: The outer wall of the first reinforcing fiber (3) is coated with a first heat-resistant polyester PET layer (30); the thickness of the first heat-resistant polyester PET layer (30) is 10-25 microns; the outer wall of the second reinforcing fiber (4) is coated with a second heat-resistant polyester PET layer (40); the thickness of the second heat-resistant polyester PET layer (40) is 10-25 microns; the polyester release cloth has a tensile strength in the warp direction of >1350N, a tensile strength in the weft direction of >1200N, and a gram weight of 95-110g / m 2 .

10. The polyester release cloth for polyurethane molding process according to claim 9, characterized in that: A fluorosilicone resin layer (100) is integrally formed on the surface of the polyester release cloth through an impregnation process.

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