High-reflection flash spinning film

Abstract

The invention relates to a high-reflection flash spinning film, the raw material of the flash spinning film comprises polyethylene, and the reflectivity of the unit fineness of the flash spinning film is 0.22-0.99 micron <-1 > in the visible light wavelength range of 350-800 nanometers; the reflectivity per unit fineness = reflectivity / average diameter of the fiber; the test method of the reflectivity is as follows: ISO (International Standardization Organization) 9050: 2003. The flash spinning film provided by the invention has relatively high reflection performance, and is particularly applied to the technical field of agricultural mulching films.

Description

Technical Field

[0001] The present invention relates to the technical field of thin films, and specifically, to a highly reflective flash-spun film. Background Art

[0002] Common types of highly reflective thin flash-spun film materials and their reflection mechanisms are as follows: (1) Metal reflection films. Common types: Commonly, there are aluminum films, silver films, gold films, etc. Reflection mechanism: It is mainly based on the collective oscillation of free electrons, that is, plasma resonance. When light is incident on the metal surface, the free electrons in the metal will undergo collective oscillation under the action of the electric field. This oscillation will interact with the incident light, causing most of the light to be reflected back. Metals have high electrical conductivity and can quickly respond to changes in the electric field, thus strongly reflecting light. For example, silver has an extremely high reflectivity in the visible light range because silver has a high density of free electrons and the plasma resonance frequency matches well with the visible light frequency.

[0003] (2) Dielectric reflection films. Common types: Such as multi-layer film structures made of dielectric materials such as titanium dioxide (TiO2) and silicon dioxide (SiO2). Mechanism: Utilize the principle of optical interference. A multi-layer film structure is formed by alternately stacking dielectric materials with different refractive indices. When light propagates in these film layers, reflection and transmission will occur at different interfaces. By precisely designing the thickness and refractive index of the film layers, constructive interference can be generated among the reflected lights of specific wavelengths in each layer, thereby achieving high reflection. In a multi-layer film composed of dielectric materials with high refractive index and low refractive index alternately, when light is incident, the reflected lights at each interface will, according to the relationship between the film layer thickness and refractive index, achieve in-phase superposition at certain specific wavelengths, enhancing the reflection effect.

[0004] (3) Metal-dielectric composite reflection films. Types: Composed of a combination of a metal layer and a dielectric layer. Reflection mechanism: Combines the reflection characteristics of metals and dielectrics. The metal layer provides a relatively high initial reflectivity, while the dielectric layer can further enhance the reflection or improve other characteristics by adjusting the optical properties. Covering a suitable dielectric material on the metal surface can reduce oxidation and scattering on the metal surface and improve the stability of the reflectivity. At the same time, the dielectric layer can also play roles such as protecting the metal layer and adjusting the reflection spectral range.

[0005] (4) Plastic film, usually made of PE, PVC, etc. It features uniform thickness, ensuring consistent coverage and enabling the soil to receive relatively uniform heat preservation, water retention, etc. Generally, the thickness of the plastic film is usually around dozens of microns. The plastic film can adapt to farmland with different terrains, is not easily broken or damaged during the laying process, and can be easily stretched and covered, conforming to the undulations of the ground to ensure good coverage. However, the reflectivity of the plastic film is not very high, which is a common problem. This should be determined by the extrusion stretching process in the manufacturing process. The low reflectivity is one of the defects in the application of plastic film.

[0006] However, the preparation process of this application is completely different from that of traditional high-emission films. It takes a different approach and uses the flash spinning process to spin the polyethylene raw material and then make a film. By taking advantage of the orderly distribution of flash fibers in the film, a good reflection effect is achieved, especially having broad application prospects in the field of agricultural mulch films. Summary of the Invention

[0007] The purpose of the present invention is to overcome the technical problem of the low emissivity of the flash-spun film used in the field of agricultural mulch films and provide a high-reflection flash-spun film.

[0008] The purpose of the present invention is achieved through the following technical solutions: A high-reflection flash-spun film, the raw material of the flash-spun film contains polyethylene, and within the visible light wavelength range of 350 - 800 nanometers, the reflectivity per unit fineness of the flash-spun film is 0.22 - 0.99 microns -1 ; Reflectivity per unit fineness = Reflectivity / Average diameter of the fiber; The test method for reflectivity is: ISO 9050:2003. The reflectivity per unit fineness of the flash-spun film is 0.22 - 0.32 microns -1 .

[0009] The reflectivity per unit fineness of the flash-spun film is 0.32 - 0.42 microns -1 .

[0010] The reflectivity per unit fineness of the flash-spun film is 0.42 - 0.52 microns -1 .

[0011] The reflectivity per unit fineness of the flash-spun film is 0.52 - 0.62 microns -1 .

[0012] The reflectivity per unit fineness of the flash-spun film is 0.62 - 0.72 microns -1 .

[0013] The reflectivity per unit fineness of the flash-spun film is 0.72 - 0.82 microns -1 .

[0014] The reflectivity of the flash-spun film per unit fineness is 0.82 - 0.92 microns -1 。

[0015] The reflectivity of the flash-spun film per unit fineness is 0.92 - 0.99 microns -1 。

[0016] In the visible light wavelength range of 350 - 800 nanometers, the reflectivity of the flash-spun film is 0.89 - 0.99

[0017] In the visible light wavelength range of 350 - 800 nanometers, the reflectivity of the flash-spun film is 0.89 - 0.92

[0018] In the visible light wavelength range of 350 - 800 nanometers, the reflectivity of the flash-spun film is 0.92 - 0.95

[0019] In the visible light wavelength range of 350 - 800 nanometers, the reflectivity of the flash-spun film is 0.95 - 0.97

[0020] In the visible light wavelength range of 350 - 800 nanometers, the reflectivity of the flash-spun film is 0.97 - 0.99

[0021] A processing method of a highly reflective flash-spun film, characterized in that the technical steps it includes are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 7 - 16%; Among them, the polymer is polyethylene and the like; the spinning solvent is aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, unsaturated hydrocarbons, halogenated hydrocarbons, alcohols, esters, ethers, ketones, nitriles, amides, fluorocarbons, sulfur dioxide, carbon disulfide, nitromethane, water and a mixture of one or more of the above substances; (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning component to obtain flash fibers, and then web laying and hot rolling are carried out to obtain a highly reflective flash-spun film; Among them, the spinneret plate of the spinning component is arranged in three layers, with three spinneret holes in the upper layer, four spinneret holes in the middle layer, and three spinneret holes in the lower layer; and the sizes of each spinneret hole are the same, and the diameter of the spinneret hole is 0.075 - 0.1 mm

[0022] During the hot rolling process, the hot rolling temperature is controlled at 105 - 115 °C, the hot rolling pressure is controlled at 0.5 MPa - 2 MPa, and the hot rolling time is controlled at 10 - 30 s

[0023] When the hot rolling pressure and a shorter time (less than 1 MPa, less than 10 s) are used, a lower reflectivity per unit fineness less than 0.22 microns is obtained -1. The main reasons are: (1) The degree of fiber bonding is limited: the low hot rolling pressure makes the bonding between flash-spun fibers not tight enough, and there are still many gaps and relatively independent structures between the fibers. The short hot rolling time is not enough for the fibers to fully fuse and deform. The fibers basically maintain the initial state after flash spinning. This relatively loose structure is not conducive to multiple reflections and scattering of light. Light can easily penetrate the gaps between fibers, making the amount of light involved in reflection relatively small, resulting in low reflectivity. (2) The fiber surface morphology changes little: under such hot rolling conditions, the pressure and action time on the fiber surface are limited, and its surface morphology does not change significantly, and still maintains a certain degree of roughness and irregularity. This not-so-smooth surface will cause light to be diffusely reflected during reflection, and some light will scatter in different directions, unable to form concentrated, high-intensity reflections, which in turn leads to a low reflectivity per unit fineness.

[0024] As the spinneret hole increases, the internal structure of the fiber becomes looser or more uneven. When light is incident on the fiber, more light enters the fiber and is scattered and absorbed, which reduces the reflected light and reduces the reflectivity, ultimately significantly reducing the reflectivity per unit fineness of the product.

[0025] Compared with the prior art, the present invention has the following positive effects: This application adopts the design of this spinneret and accurately controls the hot rolling process parameters, which can make the diameter of the flash-steamed fiber thinner and the bonding state between fibers better, which is beneficial to the reflection of light and meets the demand for higher reflectivity in the field of agricultural mulch films. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the spinneret of the present application.

[0027] The marks in the accompanying drawings are: 1 is a spinneret hole. DETAILED DESCRIPTION

[0028] A specific embodiment of a highly reflective flash-spun membrane of the present invention is provided below.

[0029] Example 1 A method for processing a highly reflective flash-spun membrane comprises the following technical steps: (1) dissolving the polymer in a spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 7%; wherein the polymer is polyethylene; The spinning solvent is cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1H-perfluoroheptane, and 1,1,1,3,3-pentafluorobutane, and the mass ratio of the four is 5:3:1:1; (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning component. The temperature of flash spinning is 220 ± 5 °C to obtain flash fibers, and then web laying and hot rolling are carried out. The temperature of hot rolling is 110 ± 3 °C to obtain a highly reflective flash-spun film. Among them, as Figure 1 shown, the spinneret of the spinning component is arranged in three layers. Among them, there are three spinneret holes 1 in the upper layer, four spinneret holes 1 in the middle layer, and three spinneret holes 1 in the lower layer; and the size of each spinneret hole 1 is the same, and the diameter of the spinneret hole is 0.085 mm.

[0030] During the hot rolling process, the hot rolling temperature is controlled at 110 °C, the hot rolling pressure is controlled at 0.6 MPa, and the hot rolling time is controlled at 12 s.

[0031] Example 2 A processing method of a highly reflective flash-spun film, and the technical steps included are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 10%. Among them, the polymer is polyethylene. The spinning solvent is cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1H-perfluoroheptane, 1,1,1,3,3-pentafluorobutane, and the mass ratio of the four is 5:3:1:1. (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning component. The temperature of flash spinning is 220 ± 5 °C to obtain flash fibers, and then web laying and hot rolling are carried out. The temperature of hot rolling is 110 ± 3 °C to obtain a highly reflective flash-spun film. Among them, as Figure 1 shown, the spinneret of the spinning component is arranged in three layers. Among them, there are three spinneret holes 1 in the upper layer, four spinneret holes 1 in the middle layer, and three spinneret holes 1 in the lower layer; and the size of each spinneret hole 1 is the same, and the diameter of the spinneret hole is 0.085 mm.

[0032] During the hot rolling process, the hot rolling temperature is controlled at 110 °C, the hot rolling pressure is controlled at 1.4 MPa, and the hot rolling time is controlled at 19 s.

[0033] Example 3 A processing method of a highly reflective flash-spun film, and the technical steps included are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 13%. Among them, the polymer is polyethylene. The spinning solvent is cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1H-perfluoroheptane, 1,1,1,3,3-pentafluorobutane, and the mass ratio of the four is 5:3:1:1. (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning assembly. The temperature of the flash spinning is 220 ± 5 °C to obtain flash fibers, and then web laying and hot rolling are carried out. The temperature of the hot rolling is 110 ± 3 °C to obtain a highly reflective flash spun film; Among them, as Figure 1 shown, the spinneret plate of the spinning assembly is arranged in three layers. There are three spinneret holes 1 in the upper layer, four spinneret holes 1 in the middle layer, and three spinneret holes 1 in the lower layer; and the size of each spinneret hole is the same, and the diameter of the spinneret hole is 0.085 mm.

[0034] During the hot rolling process, the hot rolling temperature is controlled at 110 °C, the hot rolling pressure is controlled at 2 MPa, and the hot rolling time is controlled at 28 s.

[0035] Comparative Example 1 A processing method of a highly reflective flash spun film, and the technical steps included are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 10%; Among them, the polymer is polyethylene; The spinning solvent is cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1H-perfluoroheptane, 1,1,1,3,3-pentafluorobutane, and the mass ratio of the four is 5:3:1:1; (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning assembly. The temperature of the flash spinning is 220 ± 5 °C to obtain flash fibers, and then web laying and hot rolling are carried out. The temperature of the hot rolling is 110 ± 3 °C to obtain a highly reflective flash spun film; Among them, as Figure 1 shown, the spinneret plate of the spinning assembly is arranged in three layers. There are three spinneret holes 1 in the upper layer, four spinneret holes 1 in the middle layer, and three spinneret holes 1 in the lower layer; and the size of each spinneret hole is the same, and the diameter of the spinneret hole is 0.085 mm.

[0036] During the hot rolling process, the hot rolling temperature is controlled at 110 °C, the hot rolling pressure is controlled at 0.3 MPa, and the hot rolling time is controlled at 5 s.

[0037] Comparative Example 2 A processing method of a highly reflective flash spun film, and the technical steps included are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 10%; Among them, the polymer is polyethylene; The spinning solvent is cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1H-perfluoroheptane, 1,1,1,3,3-pentafluorobutane, and the mass ratio of the four is 5:3:1:1; (2) The spinning solution obtained in step (1) is subjected to flash spinning through a spinning pack. The temperature of the flash spinning is 220 ± 5 °C to obtain flash fibers, and then web laying and hot rolling are carried out. The temperature of the hot rolling is 110 ± 3 °C to obtain a highly reflective flash-spun film. Among them, as Figure 1 shown, the spinneret plate of the spinning pack is arranged in three layers. The upper layer has three spinneret holes 1, the middle layer has four spinneret holes 1, and the lower layer has three spinneret holes 1; and the size of each spinneret hole is the same, and the diameter of the spinneret hole is 0.15 mm.

[0038] During the hot rolling process, the hot rolling temperature is controlled at 110 °C, the hot rolling pressure is controlled at 1.4 MPa, and the hot rolling time is controlled at 19 s.

[0039] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A highly reflective flash spun film, characterized in that, The raw material of the electrospun film contains polyethylene. In the visible light wavelength range of 350 to 800 nanometers, the reflectivity of the electrospun film per unit fineness is 0.22 to 0.99 micrometers -1 ; Reflectivity per unit fineness = Reflectivity / average diameter of the fiber; The test method for reflectivity is: ISO 9050:2003.

2. The highly reflective flash-spun film according to claim 1, wherein The reflectivity of the spunbond film per unit fineness is 0.22 to 0.32 microns -1 .

3. The highly reflective spunbond film according to claim 1, characterized in that, The reflectivity of the spunbond film per unit fineness is 0.32 to 0.42 microns -1 .

4. A highly reflective flash-spun film as claimed in claim 1, wherein The reflectance of the spunbond film per unit fineness is 0.42 to 0.52 microns -1 .

5. The highly reflective flash-spun film according to claim 1, characterized in that, The reflectance of the spunbond film per unit fineness is 0.52 to 0.62 microns -1 .

6. The highly reflective spunbond film according to claim 1, wherein The reflectivity of the spunbond film per unit fineness is 0.62 to 0.72 microns -1 .

7. A highly reflective flash-spun film according to claim 1, characterized in that, The reflectance of the spunbond film per unit fineness is 0.72 to 0.82 microns -1 .

8. The highly reflective flash-spun film according to claim 1, wherein, The reflectance of the spunbond film per unit fineness is 0.82 to 0.92 microns -1 .

9. The highly reflective flash-spun film according to claim 1, wherein, The reflectivity of the flash-spun film per unit fineness is 0.92 to 0.99 microns -1 .

10. A highly reflective flash-spun film as claimed in claim 1, wherein In the visible light wavelength range of 350 - 800 nm, the reflectivity of the flash-spun film is 0.89 - 0.

99.

11. The highly reflective flash-spun film according to claim 1, wherein, In the visible light wavelength range of 350 - 800 nm, the reflectivity of the flash-spun film is 0.89 - 0.

92.

12. A highly reflective flash-spun film as claimed in claim 1, wherein, In the visible light wavelength range of 350 - 800 nm, the reflectivity of the flash-spun film is 0.92 - 0.

95.

13. A highly reflective flash-spun film as claimed in claim 1, wherein, In the visible light wavelength range of 350 - 800 nm, the reflectivity of the flash-spun film is 0.95 - 0.

97.

14. A highly reflective flash-spun film according to claim 1, characterized in that, In the visible light wavelength range of 350 - 800 nm, the reflectivity of the flash-spun film is 0.97 - 0.

99.

15. The processing method of a highly reflective flash-spun film as claimed in claim 1, characterized in that, The technical steps it includes are: (1) Dissolve the polymer in the spinning solvent to form a spinning solution; the mass fraction of the polymer in the spinning solution is 7 - 16%; (2) The spinning solution obtained in step (1) undergoes flash spinning through a spinning pack to obtain flash-spun fibers, and then web laying and hot rolling are carried out to obtain a highly reflective flash-spun film; Among them, the spinneret plate of the spinning pack is arranged in three layers, with three spinneret holes in the upper layer, four spinneret holes in the middle layer, and three spinneret holes in the lower layer; and the size of each spinneret hole is the same.

16. The processing method of a highly reflective flash-spun film according to claim 15, characterized in that, The diameter of the spinneret hole is 0.075 - 0.1 mm; during the hot rolling process, the hot rolling temperature is controlled at 105 - 115 °C, the hot rolling pressure is controlled at 0.5 MPa - 2 MPa, and the hot rolling time is controlled at 10 - 30 s.

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