Fabric capable of not imaging after scattering sunlight based on Tyndall effect and preparation method thereof

Abstract

The invention belongs to the technical field of functional fabrics, and particularly discloses a fabric capable of not imaging after scattering sunlight based on the Tyndall effect and a preparation method of the fabric. The fabric capable of not imaging by scattering sunlight based on the Tyndall effect comprises composite flat fibers, the composite flat fiber sequentially comprises a high-permeability membrane layer, a hollow particle layer and a semi-gloss membrane layer; the hollow particle layer is prepared from polyurethane glue and hollow particles. The hollow particles comprise at least one of hollow silicon dioxide and aluminum oxide. According to the design, light scattering points are formed in the adhesive layer through the hollow silicon dioxide, and incident light is subjected to multiple refraction in the fiber in cooperation with the light diffusion characteristic of the semi-gloss PET. Finally, the fabric achieves a non-imaging privacy effect (the contour of a human body cannot be recognized outdoors), meanwhile, the high UVA blocking rate and the high light transmission retention rate are achieved, and the contradiction between the light transmission of a traditional window screen and privacy protection is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional fabric, and particularly discloses a non-imaging fabric for scattering sunlight based on the Tyndall effect and a preparation method thereof. BACKGROUND

[0002] In building decoration, home life and specific industrial scenes, light-transmitting non-see-through cloth, as a special material with both lighting needs and privacy protection functions, has an increasing demand for application. The core feature of light-transmitting non-see-through cloth is that it can allow light to effectively penetrate to ensure the supply of indoor natural light while preventing clear observation of objects on the other side of the cloth from the outside, thereby creating a safe and private environment for users on the basis of meeting the space brightness requirement. This type of cloth is widely used in product fields such as window screens, partition curtains, indoor decorative curtains and the like.

[0003] However, the current market traditional light-transmitting non-see-through cloth has obvious limitations in the technical path for achieving the balance between light transmission and privacy, and it is difficult to simultaneously meet the comprehensive needs of high light transmittance, good privacy protection and light weight. Specifically, the traditional products mainly realize the functions through two technical means: one is to adjust the physical weaving density to reduce direct light and block the line of sight by encrypting the fabric structure, but this way often leads to a significant decrease in light transmittance; the other is to adjust the opacity of the material itself to achieve privacy protection by selecting high light-blocking raw materials, but it also sacrifices the light penetration ability. From the actual product performance, the products under the existing technology have obvious performance short boards: on the one hand, high light-transmitting window screens (such as common glass fiber screen products) can achieve a light transmittance of more than 70% to ensure sufficient indoor lighting, but since the light penetrates in the form of direct light, it is easy to form glare in the room, affecting visual comfort, and because the fabric structure is loose, the indoor scene can be clearly seen from the outside, and the problem of privacy leakage is prominent; on the other hand, high-privacy window screens (such as thick and dense polyester screen products) can achieve better privacy protection through high-density structure or high-light-blocking material, but their light transmittance is generally less than 40%, leading to insufficient indoor natural light supply, and relying on artificial light in daily use increases energy consumption. At the same time, the grammage of this type of product is generally more than 150 g / m 2 , the material is thick and heavy, which not only affects the installation convenience and use flexibility of the product, but also increases the load of the supporting structure such as window frame, limiting its application in some scenes.

[0004] To solve the contradiction between light transmittance, privacy protection and light weight of traditional light-transmitting non-see-through cloth, it is urgently needed in the industry to develop a window screen product based on a new technical path, which can ensure high light transmittance to meet the demand for natural light, achieve good privacy protection to avoid information leakage, and at the same time, reduce the grammage of the product to achieve lightweight design of the structure, so as to adapt to a wider range of application scenarios and meet the market demand for high-performance light-transmitting non-see-through cloth.

[0005] To solve the above problems, the application provides a solution based on a new composite structure, the core innovation of which is to break through the performance bottleneck of traditional technology by constructing a synergistic system of "hollow particle layer + semi-light film layer". Specifically, the micro-particles of the hollow particle layer scatter light, making the light passing through the hollow particle layer have a bright light path, similar to the Tyndall effect. However, the micro-particles of the hollow particle layer in the application do not reach the nanometer level specified by the Tyndall effect. Since the role of the micro-particles of the hollow particle layer in the application and the Tyndall effect both belong to light scattering phenomena, and both are the process of light deviating from the original direction and spreading around after encountering small particles, the basic physical processes are the same. In addition, due to the similar visual performance, both produce a bright light path that can be seen from the side (i.e., the bright light path produced by the hollow particle layer in the application), the phenomenon of light produced by the hollow particle layer in the application is described as the Tyndall effect. In other words, the Tyndall effect described in the application describes the light scattering behavior of light passing through the hollow particle layer.

[0006] More importantly, the application also provides a semi-light film layer based on the hollow particle layer, so that the light scattering formed by the hollow particle layer and the light diffusion characteristics of the semi-light film layer are synergistic, the incident light occurs multiple refraction inside the fiber, and finally forms a light path that cannot be seen from the side. The entire surface emits uniform, soft and blurred light, so that the window screen has the advantages of light transmission and privacy protection, and compared with traditional high-privacy products, the composite structure does not need to rely on thick materials to achieve the performance target, laying a foundation for lightweight design of the product. SUMMARY

[0007] The application provides a non-imaging fabric based on the Tyndall effect for scattering sunlight, comprising a composite flat fiber.

[0008] Preferably, the width of the composite flat fiber is 0.21-0.77mm.

[0009] Preferably, the composite flat fiber comprises a high-transparency film layer, a hollow particle layer and a semi-light film layer in sequence.

[0010] Preferably, the hollow particle layer is made of polyurethane glue and hollow particles.

[0011] Preferably, the hollow particles comprise at least one of hollow silica and aluminum oxide.

[0012] Preferably, the material of the high-transparency film layer is PET or EVA.

[0013] Preferably, the mass of the hollow particles is 2-5% of the mass of the polyurethane glue.

[0014] Preferably, the hollow silica has a particle size of 1-3 μm and a hollow rate of ≥80%.

[0015] Preferably, the alumina has a particle size of 1-4 μm.

[0016] Preferably, the high-transparency film layer has a light transmittance of ≥92% and a haze of <1%.

[0017] Preferably, the semi-light film layer has a light transmittance of 70-80% and a haze of 15-20%.

[0018] Preferably, the semi-light film layer is made of PET or EVA.

[0019] Further, the preparation method of the composite flat fiber comprises the following steps: S11: coating a coating liquid made of polyurethane glue and hollow microparticles on one side of a high-transparency PET film, using micro-gravure coating, and drying to obtain a hollow microparticle layer with a thickness of 2-5 μm; S12: performing corona treatment and coating glue on one side of a semi-light film, and then laminating the hollow microparticle layer obtained in step S11 to obtain a composite film through hot pressing; S13: slitting the composite film to obtain a composite flat fiber.

[0020] Further, the polyurethane glue in step S11 has a solid content of 30-40%.

[0021] Further, the semi-light film after corona treatment in step S12 has a surface energy of ≥40 mN / m.

[0022] Further, the glue in step S12 is water-based polyurethane.

[0023] Further, the glue coating amount in step S12 is 2-8 g / m 2 .

[0024] Further, the hot pressing temperature in step S12 is 80-100°C, the pressure is 0.3-0.5 MPa, and the speed is 5-10 m / min.

[0025] Further, the preparation method of the non-imaging fabric based on scattering sunlight by the Tyndall effect comprises the following steps: weaving the composite flat fiber as warp yarn, with the flat surface of the composite flat fiber facing the surface of the fabric, and using high-transparency PET film as the front surface to obtain the non-imaging fabric based on scattering sunlight by the Tyndall effect.

[0026] Further, the fabric is a woven fabric, the flat surface of the composite flat fiber faces the surface of the fabric, and the fabric has a grammage of 60-100 g / m 2The warp density of the fabric is 24-36 per centimeter, which is adjusted according to the slitting width, and ensures that the coverage factor is stable; and the weight percentage of the weft yarn is less than 10% of the fabric weight.

[0027] Preferably, the weft yarn of the fabric is low-elasticity polyester.

[0028] In an embodiment of the present application, the low-elasticity polyester is 75D.

[0029] The present application has the following advantages: The present application adopts a three-layer composite film with a specific structure to prepare a composite flat fiber: a high-transparency PET film is used as a base layer, a polyurethane glue containing hollow silica is coated on the surface of the base layer to form a 3-micron scattering functional layer-hollow particle layer, and a semi-light PET film is further compounded as an optical control layer to obtain the composite flat fiber. The design forms light scattering points in the glue layer by using hollow silica, and cooperates with the light diffusion characteristics of the semi-light PET to make the incident light undergo multiple refraction in the fiber. Finally, the fabric realizes a non-imaging privacy effect (the human body contour cannot be recognized outdoors), while having high UVA blocking rate and high light transmission retention rate, and solves the contradiction between the light transmission and privacy protection of traditional window screens. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a structural schematic diagram of the composite flat fiber; Figures 2-4 FIG. 3 shows the scattering effect of the fabric on light, in which a laser is used as a point light source to irradiate the fabric, and the light is obviously scattered to form a light halo after penetrating the fabric. DETAILED DESCRIPTION

[0031] The high-transparency PET film (brand: Hengli, model: GP high-transparency) used in the following examples and comparative examples has a light transmittance ≥92% and a haze <1%; The semi-light PET film (brand: Hengli, model: GP semi-transparency) has a light transmittance of 70-80% and a haze of 15-20%; The hollow silica (brand: XFNANO) has a particle size of 1.5 microns (except as otherwise specified) and a hollow rate ≥80%; The alumina (brand: XFNANO) has a particle size of 3 microns; The polyurethane glue is a water-based polyurethane glue (brand: Archroma, model: Mowipur 1925) with a solid content of 35 wt%; The 75D low-elasticity polyester (brand: Hengli, model: DTY low-elasticity).

[0032] Example 1: S1: Preparation of the composite flat fiber: S11: A coating liquid made of polyurethane glue and hollow silica is coated on one side of a 10 μm thick high-transmittance PET film, wherein the mass of the hollow silica is 2% of the mass of the polyurethane glue, and micro-gravure coating is used in the coating process. After drying, a hollow particle layer with a thickness of 3 μm is obtained; S12: One side of a 10 μm semi-gloss PET film is subjected to corona treatment to make the surface reach a Darcy value of 42 mN / m, and polyurethane glue (diluted with water to 25 ℃-4 cup viscosity 40-48 s) is coated, with a coating amount of 3 g / m 2 Then, the hollow particle layer of the film obtained in step S11 is laminated, 90 ℃ hot pressing, pressure 0.3 MPa, speed 5 m / min, to obtain a composite film; S13: The composite film is cut, and a laser cutting all-in-one machine (Yinghe Technology YHLC800A) is used to cut the composite flat fiber with a width of 0.5 mm.

[0033] S2: Preparation of a non-imaging fabric based on the scattering of sunlight by the Tyndall effect: The composite flat fiber is used as the warp yarn with a warp density of 30 per centimeter, the flat surface of the composite flat fiber faces the surface of the fabric, the high-transmittance PET film is used as the front surface, and the 75D low-elasticity polyester is used as the weft yarn with a mass of 8% of the mass of the fabric. The fabric is woven into a non-imaging fabric based on the scattering of sunlight by the Tyndall effect, with a mass of 85 g / m 2 .

[0034] Example 2: Example 2 differs from Example 1 in that the mass of the hollow silica in step S11 is 3% of the mass of the polyurethane glue, and the rest is the same as in Example 1.

[0035] Example 3: Example 3 differs from Example 1 in that the mass of the hollow silica in step S11 is 4% of the mass of the polyurethane glue, and the rest is the same as in Example 1.

[0036] Example 4: Example 4 differs from Example 1 in that the mass of the hollow silica in step S11 is 5% of the mass of the polyurethane glue, and the rest is the same as in Example 1.

[0037] Example 5

[0038] S1: Preparation of a composite flat fiber: S11: A coating liquid made of polyurethane glue and hollow silica is coated on one side of a 10 μm thick high-transmittance PET film, wherein the mass of the hollow silica is 3% of the mass of the polyurethane glue, and micro-gravure coating is used in the coating process. After drying, a hollow particle layer with a thickness of 3.5 μm is obtained; S12: One side of 10 μm semi-gloss PET film was treated by corona discharge to make the surface reach a Darcy value of 42 mN / m, and polyurethane glue (viscosity 1000 mPa·s) was coated, with a coating amount of 3 g / m 2 Then, the hollow particle layer of the film obtained in step S11 was laminated, and hot pressing was performed at 90°C, with a pressure of 0.4 MPa and a speed of 7 m / min, to obtain a composite film. S13: The composite film was cut to obtain a composite flat fiber with a width of 0.45 mm.

[0039] S2: Preparation of a non-imaging fabric for scattering sunlight based on the Tyndall effect: The composite flat fiber was used as the warp yarn, with a warp density of 30 per centimeter, and the flat surface of the composite flat fiber faced the surface of the fabric. High-transmittance PET film was used as the front surface, and 75D low-elasticity polyester was used as the weft yarn, with a weft yarn mass accounting for 8% of the mass of the fabric. The fabric was woven into a non-imaging fabric for scattering sunlight based on the Tyndall effect.

[0040] Example 6

[0041] S1: Preparation of a composite flat fiber: S11: A coating liquid prepared from polyurethane glue and hollow particles (hollow silica / alumina in a mass ratio of 1:1) was coated on one side of a 12 μm thick high-transmittance PET film, with the mass of the hollow particles accounting for 3.5% of the mass of the polyurethane glue, to obtain a hollow particle layer with a thickness of 4 μm; S12: One side of 11 μm semi-gloss PET film was treated by corona discharge to make the surface reach a Darcy value of 43 mN / m, and polyurethane glue (viscosity 1100 mPa·s) was coated, with a coating amount of 3.1 g / m 2 Then, the hollow particle layer of the film obtained in step S11 was laminated, and hot pressing was performed at 95°C, with a pressure of 0.35 MPa and a speed of 8 m / min, to obtain a composite film. S13: The composite film was cut to obtain a composite flat fiber with a width of 0.3 mm.

[0042] S2: Preparation of a non-imaging fabric for scattering sunlight based on the Tyndall effect: The composite flat fiber was used as the warp yarn, with a warp density of 33 per centimeter, and the flat surface of the composite flat fiber faced the surface of the fabric. High-transmittance PET was used as the front surface, and 75D low-elasticity polyester was used as the weft yarn, with a weft yarn mass accounting for 7% of the mass of the fabric. The fabric was woven into a non-imaging fabric for scattering sunlight based on the Tyndall effect.

[0043] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step S11 is changed to: coating polyurethane adhesive on one side of a 10 μm thick high-transmittance PET film, and after drying, a 3 μm thick polyurethane adhesive layer is obtained; the rest is the same as Example 1.

[0044] Comparative Example 2: S1: Preparation of composite flat fiber: S11: Coating a coating liquid prepared from polyurethane adhesive and hollow silica on one side of a 10 μm thick high-transmittance PET film, wherein the mass of hollow silica is 2% of the mass of polyurethane adhesive, and the coating process adopts micro-gravure coating, and after drying, a 3 μm thick hollow particle layer is obtained to prepare a composite film; S13: Cutting the composite film, and the cutting adopts a laser cutting all-in-one machine (Yinghe Technology YHLC800A) to prepare a composite flat fiber with a width of 0.5 mm; S2: Preparation of a non-imaging fabric based on the scattering of sunlight by the Tyndall effect: The composite flat fiber is used as warp yarn with a warp density of 30 per centimeter, the flat surface of the composite flat fiber faces the surface of the fabric, high-transmittance PET is used as the front surface, 75D low-elasticity polyester is used as weft yarn, the mass of weft yarn accounts for 8% of the mass of the fabric, and the fabric organization is plain weave to weave the non-imaging fabric based on the scattering of sunlight by the Tyndall effect.

[0045] Comparative Example 3: S1: Preparation of composite flat fiber: S11: Coating a coating liquid prepared from polyurethane adhesive and hollow silica on one side of a 10 μm thick high-transmittance PET film, wherein the mass of hollow silica is 2% of the mass of polyurethane adhesive, and the coating process adopts micro-gravure coating to form a hollow particle layer, and the coating amount is the same as Example 1; S12: Corona treatment is performed on one side of a 10 μm semi-gloss PET film to make the surface of the film reach a Darcy value of 42 mN / m, and then the film is laminated with the hollow particle layer obtained in step S11, and hot pressing is performed at 90°C, the pressure is 0.3 MPa, and the speed is 5 m / min to obtain a composite film; S13: Cutting the composite film, and the cutting adopts a laser cutting all-in-one machine (Yinghe Technology YHLC800A) to prepare a composite flat fiber with a width of 0.5 mm.

[0046] S2: Preparation of a non-imaging fabric based on the scattering of sunlight by the Tyndall effect: The composite flat fiber is used as warp yarn with a warp density of 30 per centimeter, the flat surface of the composite flat fiber faces the surface of the fabric, high-transmittance PET film is used as the front surface, 75D low-elasticity polyester is used as weft yarn, the mass of weft yarn accounts for 8% of the mass of the fabric, and the fabric organization is plain weave to weave the non-imaging fabric based on the scattering of sunlight by the Tyndall effect.

[0047] Performance testing: Light transmittance: GB / T 2410-2008; Privacy: During the day when there is sufficient natural light, after drawing the curtains, stand indoors near the curtains (20cm away from the curtains, facing the curtains) and observe from 5m outdoors. Record the following: whether the outline of the person can be identified, whether the outline is clearly identified, and whether details such as the color of the face or clothing can be identified. UV protection: GB / T 18830-2009, test and calculate UVA blocking rate; Weather resistance: The fabric was exposed to sunlight for 6 months. The light transmittance of the fabric before and after exposure was tested. The light transmittance retention rate was calculated using the following formula: Light transmittance retention rate (%) = (Light transmittance after exposure / Light transmittance before exposure) × 100%; Scattering angle: Cut 10cm×10cm fabric samples (3 pieces each in the warp and weft directions), install them in the sample holder, apply a pretension of 0.5cN / tex, and incident a laser (650nm wavelength semiconductor laser, power ≤5mW, beam diameter ≤1mm) perpendicularly to the center point of the sample. Record the peak transmitted light intensity (I0), and use a detector (CCD imaging system) to record the transmitted light intensity distribution (I0) from 0 to 90° in 1° increments. θ ), calculate the light intensity ratio: light intensity ratio = 100 × I θ / I0; The maximum angular range with a light intensity ratio ≥10% is taken as the scattering angle result, and the final data is the average value of 6 samples.

[0048] The performance test results are shown in Table 1.

[0049] Table 1 Performance test results of Examples 1-6 and Comparative Examples 1-3

[0050] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A fabric that scatters sunlight without creating an image based on the Tyndall effect, characterized in that, It includes composite flat fibers; the composite flat fibers sequentially include a high-transparency membrane layer, a hollow microparticle layer and a semi-light membrane layer; the hollow microparticle layer is made of polyurethane adhesive and hollow microparticles.

2. The non-image-forming fabric based on the Tyndall effect for scattering sunlight as described in claim 1, characterized in that, The high-transmittance film layer has a light transmittance of ≥92% and a haze of <1%; the semi-transmittance film layer has a light transmittance of 70-80% and a haze of 15-20%; the material of the semi-transmittance film layer or the high-transmittance film layer is PET or EVA.

3. The non-image-forming fabric based on the Tyndall effect for scattering sunlight as described in claim 1, characterized in that, The mass of the hollow microparticles is 2-5% of the mass of the polyurethane adhesive.

4. The non-image-forming fabric based on the Tyndall effect for scattering sunlight as described in claim 1, characterized in that, The hollow microparticles include at least one of hollow silica and alumina; the hollow silica has a particle size of 1-3 μm and a hollowness of ≥80%; the alumina has a particle size of 1-4 μm.

5. The non-image-forming fabric based on the Tyndall effect for scattering sunlight as described in claim 1, characterized in that, The method for preparing the composite flat fiber includes the following steps: S11: A coating liquid made of polyurethane adhesive and hollow microparticles is coated on one side of a high-transparency PET film. The coating process adopts micro-gravure coating. After drying, a hollow microparticle layer with a thickness of 2-5μm is obtained. S12: Corona treatment and adhesive coating are applied to one side of the semi-gloss film; then it is laminated with the film obtained in step S11 and hot-pressed to obtain a composite film; S13: Cut the composite membrane to obtain composite flat fibers.

6. The non-image-forming fabric based on the Tyndall effect for scattering sunlight as described in claim 5, characterized in that, The surface dyne value of the semi-gloss film after corona treatment in step S12 is ≥40 mN / m; the hot-pressing temperature in step S12 is 80-100℃, the pressure is 0.3-0.5 MPa, and the speed is 5-10 m / min; the adhesive coating amount in step S12 is 2~8 g / m 2 .

7. A method for preparing a non-image-forming fabric based on the Tyndall effect of any one of claims 1-6, characterized in that, The process includes the following steps: using composite flat fibers as warp yarns for weaving, with the flat side of the composite flat fibers facing the fabric surface, and a high-transparency PET film as the front side, to obtain a fabric that does not scatter sunlight based on the Tyndall effect.

8. The method for preparing a non-image-forming fabric based on the Tyndall effect of scattering sunlight as described in claim 7, characterized in that, The fabric is a woven fabric; the flat surface of the composite flat fiber faces the fabric surface.

9. The method for preparing a non-image-forming fabric based on the Tyndall effect of sunlight scattering as described in claim 7, characterized in that, The warp density of the fabric is 24-36 threads / cm, and the weight of the weft yarn is less than 10% of the fabric weight.

Images