Lightweight foam structure for light diffusion panels

Abstract

To provide a foam lightweight structure of a light diffusion plate.SOLUTION: A light diffusion plate includes an upper surface layer, a first foam layer, a second foam layer, and a lower surface layer which are continuously connected to each other, wherein thickness of the first foam layer is thinner than thickness of the second foam layer, and an average diameter of air bubbles of the first foam layer is smaller than an average diameter of air bubbles of the second foam layer. The upper surface layer and the lower surface layer generate an action of protecting an area from a protective layer to the first foam layer and the second foam layer. The first foam layer is used for increasing diffusion of light, and the second foam layer increases transmittance of light, and is used for lowering average density of the light diffusion plate. Thicknesses of the first foam layer and the second foam layer or the average diameter of the air bubbles is adjusted, which adjusts the average density, light transmittance and haze of the light diffusion plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light diffusion plate, and more particularly to a lightweight foam structure for a light diffusion plate and a method for producing the same. [Background technology]

[0002] Light diffusers are created by chemical or physical means when light encounters two media with different refractive indices (densities) during its travel, resulting in the physical phenomena of refraction, reflection, and scattering. By adding inorganic or organic light diffusing agents to substrates such as PMMA, PC, PS, PP, and HIPS, or by artificially adjusting the light's direction using an array of micro-features on the substrate surface, the light is refracted, reflected, and scattered in different directions, thereby changing the light's path and achieving sufficient color dispersion and optical diffusion of the incident light. Light diffusers are widely used in LCD displays, LED lighting, and imaging display systems, and their main function is to sufficiently scatter the incident light to achieve a softer, more uniform illumination effect. Summary of the Invention [Problem to be solved by the invention]

[0003] In the currently disclosed patents and technologies for foam light diffusion plates, bubbles are used as a medium for light diffusion, and the haze is increased to improve light diffusion efficiency. However, the size of the bubbles and the thickness of the plate are limited, which affects the light transmittance and haze. When the thickness remains the same, two situations occur when the density decreases. 1. The number of bubbles increases and the bubbles become smaller. 2. The number of bubbles remains the same, but the bubbles become larger. As is well known, as the number of bubbles increases and the bubbles become smaller, the light undergoes more refraction as it passes through these bubbles, reducing the light transmittance and ultimately the brightness of the display. If the thickness remains the same and the bubbles become larger and the weight becomes lighter, the light transmittance increases, but the light haze decreases, which means that the diffusion rate does not meet the required rate (90-94%). The density of these light diffusion foam boards currently in mass production is 0.8-0.85g / cm. 3 The density was only able to reach a range between 0.8g / cm and the light transmittance was only able to reach a range between 40% and 50%. 3 If it is lower, the light transmittance will be less than 40% or the haze will be less than 90%, which does not meet the standards currently required in the industry.

[0004] As rising raw material prices put pressure on product profit margins, there was a pressing need to find a way to reduce product costs while still ensuring light transmittance and light diffusion performance.

[0005] Moving beyond the conventional known technology, in order to further solve the foam lightweight structure of the light diffusion plate, a different technology of multi-layer co-extrusion molding and cellular structure layer is adopted to realize a new technological method that can control the light transmittance and light diffusion haze.

[0006] Therefore, the present inventors believed that the above drawbacks could be improved, and as a result of extensive research, they came up with the proposal of the present invention, which effectively improves the above problems through rational design.

[0007] The present invention was developed through extensive research by the inventors in light of the above-mentioned problems. Its objective is to provide a lightweight foamed light diffusion plate structure and a manufacturing method thereof. Specifically, to reduce the cost of light diffusion sheets, it is necessary to increase the number of light-transmitting bubbles and reduce light scattering and loss. Tests have proven that, when the thickness remains constant, if the density decreases and the bubbles become larger, the number of bubbles decreases, increasing light transmittance but decreasing haze. When the thickness remains constant, the density decreases and the bubbles become smaller, increasing the number of bubbles, decreasing light transmittance but increasing haze. In these two situations, changes in light diffusion or haze are detrimental to meeting the industry's requirements for light diffusion plates, but are advantageous for reducing the weight of foamed light diffusion plates, which have already been industrialized. Therefore, the present invention combines the above-mentioned foundation with one or more thin layers of fine-bubble foaming to achieve excellent light diffusion and suitable light transmittance while effectively reducing the weight of the light diffusion plate. [Means for solving the problem]

[0008] In order to solve the above problems, one embodiment of the present invention provides a lightweight foam structure for a light diffusion plate, the light diffusion plate comprising an upper surface layer, a first foam layer, a second foam layer, and a lower surface layer, which are connected in sequence, the thickness of the first foam layer being thinner than the thickness of the second foam layer, and the average diameter of the bubbles in the first foam layer being smaller than the average diameter of the bubbles in the second foam layer. The upper and lower surface layers together act to protect the first and second foam layers from the protective layer. The first foam layer is used to increase light diffusion, and the second foam layer is used to increase light transmittance and reduce the average density of the light diffusion plate.

[0009] In addition, in the lightweight foam structure of the light diffusion plate according to the present invention, the total thickness of the light diffusion plate is in the range of 1 to 5 mm, and the average density is 0.3 to 0.85 g / cm 3 The range is between .

[0010] Moreover, the lightweight foam structure of the light diffusion plate according to the present invention further comprises the first foam layer between the second foam layer and the lower surface layer.

[0011] Moreover, the lightweight foam structure of the light diffusion plate according to the present invention further comprises the second foam layer between the upper surface layer and the first foam layer.

[0012] In the lightweight foam structure for a light diffusion plate according to the present invention, the thicknesses of the upper and lower surface layers are both in the range of 0.01 to 0.05 mm. The thickness of the first foam layer is in the range of 0.2 to 1 mm, and the average diameter of the cells in the first foam layer is in the range of 0.03 to 0.08 mm. The thickness of the second foam layer is in the range of 0.78 to 3.9 mm, and the average diameter of the cells in the second foam layer is in the range of 0.3 to 0.8 mm.

[0013] In the lightweight foam structure for a light diffusion plate according to the present invention, the thicknesses of the upper surface layer and the lower surface layer are both in the range of 0.01 to 0.05 mm. The thickness of the first foam layer is in the range of 0.1 to 0.5 mm, and the average diameter of the cells in the first foam layer is in the range of 0.03 to 0.08 mm. The thickness of the second foam layer is in the range of 0.78 to 3.9 mm, and the average diameter of the cells in the second foam layer is in the range of 0.3 to 0.8 mm.

[0014] In the lightweight foam structure for a light diffusion plate according to the present invention, the thicknesses of the upper surface layer and the lower surface layer are both in the range of 0.01 to 0.05 mm. The thickness of the first foam layer is in the range of 0.2 to 1 mm, and the average diameter of the cells in the first foam layer is in the range of 0.03 to 0.08 mm. The thickness of the second foam layer is in the range of 0.39 to 1.95 mm, and the average diameter of the cells in the second foam layer is in the range of 0.3 to 0.8 mm.

[0015] In addition, in the lightweight foam structure of the light diffusion plate according to the present invention, the first foam layer can be replaced with a light diffusing agent. The light diffusing agent can be an inorganic light diffusing agent and / or an organic light diffusing agent, such as nano-barium sulfate, calcium carbonate, or silicon dioxide, and the organic light diffusing agent can be an acrylic type, a styrene monomer type, an acrylic resin type, or an organic silicon particle type.

[0016] To achieve the above object, another embodiment of the present invention provides a method for manufacturing a foamed light diffusion plate. The method combines a distributor with a screw extruder or uses an in-mold compounding method to manufacture a four- or five-layer light diffusion plate. The light diffusion plate includes an upper surface layer, a first foam layer, a second foam layer, and a lower surface layer, which are connected in sequence. The raw material compositions of the first and second foam layers include a high-polymer transparent material and a foaming agent. The high-polymer transparent material is selected from polystyrene, polypropylene, polycarbonate, and polyethylene terephthalate. When the high-polymer transparent material is polystyrene, the raw material composition further includes a reinforcing agent or a transparent thermoplastic elastomer. When the high-polymer transparent material is polycarbonate, the raw material composition further includes a reinforcing agent, and the reinforcing agent is added in a proportion of 1 to 20 wt% of the raw material composition.

[0017] In addition, in the method for manufacturing a lightweight foam structure for a light diffusion plate according to the present invention, the first foam layer uses expandable microspheres or a foaming agent, and the foaming agent is an endothermic or / and exothermic foaming agent with a pore size after foaming ranging from 0.003 to 0.005 mm, and the amount of the foaming agent ranges from 0.5 to 2 wt% of the raw material composition of the first foam layer. The second foam layer uses an endothermic or / and exothermic foaming agent with a particle size ranging from 0.050 to 0.090 mm, and the amount of the foaming agent ranges from 0.7 to 6 wt% of the raw material composition of the second foam layer. The back pressure of the mold for the in-mold composite method ranges from 2 to 25 MPa, and the mold temperature ranges from 160 to 230°C. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing the configuration of a lightweight foam structure of a light diffusion plate according to a first embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing the configuration of a lightweight foam structure of a light diffusion plate according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a schematic diagram showing the configuration of a lightweight foam structure of a light diffusion plate according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes in detail the embodiments of the present invention, but the present invention is not limited to these, and various modifications are possible within the scope of the description, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0020] (First Example) FIG. 1 is a schematic diagram showing a lightweight foam structure for a light diffusion plate according to a first embodiment of the present invention. The structure comprises an upper surface layer 1, a first foam layer 2, a second foam layer 3, and a lower surface layer 4, which are connected in sequence. The thickness of the first foam layer 2 is thinner than that of the second foam layer 3, and the diameter of the bubbles in the first foam layer 2 is smaller than that of the second foam layer 3. The upper and lower surface layers together protect the protective layer and the core layer (the core layer is a structural layer between the upper surface layer 1 and the lower surface layer 4, which in the first embodiment are the first foam layer 2 and the second foam layer 3). The bubbles in the first foam layer 2 are used to increase light diffusion, while the bubbles in the second foam layer 3 are used to increase light transmittance and reduce the average density of the foam light diffusion plate.

[0021] In the first embodiment, the light diffusion plate has a four-layer structure consisting of a core layer, a first foam layer 2 disposed between two upper and lower surface layers, and a second foam layer 3 added thereto. More specifically, the total thickness of the foam light diffusion plate in the first embodiment is in the range of 1 to 5 mm, and the thicknesses of the upper surface layer 1 and the lower surface layer 4 are both in the range of 0.01 to 0.05 mm. The thickness of the first foam layer 2 is in the range of 0.2 to 1 mm, and the average diameter of the bubbles is in the range of 0.03 to 0.08 mm. The thickness of the second foam layer 3 is in the range of 0.78 to 3.9 mm, and the average diameter of the bubbles is in the range of 0.3 to 0.8 mm.

[0022] The average density of the light diffusion plate according to the first embodiment is 0.3 to 0.85 g / cm 3The thickness can be controlled within a range between 0.01 and 0.15, the light transmittance can be controlled within a range between 40% and 60%, and the haze can be controlled within a range between 92% and 96%. Specifically, by adjusting the thickness or the diameter of the bubbles of the first foam layer 2 and the second foam layer 3, the average density, light transmittance, and haze of the light diffuser plate can be adjusted to obtain the desired light diffuser plate. Table 1 shows the relationship between different thicknesses, average density, haze, and light transmittance of the light diffuser plate according to the first embodiment.

[0023] <Table 1: Haze and light transmittance of light diffusion plates having different total thicknesses and average densities according to Example 1> TIFF0007786686000001.tif93146

[0024] (Second Example) FIG. 2 is a schematic diagram showing a lightweight foam structure of a light diffuser plate according to a second embodiment of the present invention. In this second embodiment, the four-layer structure of the light diffuser plate has been modified to a five-layer structure, with three foam layers interposed between the upper surface layer 1 and the lower surface layer 4. The core layer has a two-layer structure consisting of a first foam layer 2 and a second foam layer 3 laminated thereon, resulting in a three-layer structure of first foam layer 2-second foam layer 3-first foam layer 2. More specifically, the total thickness of the light diffuser plate according to the second embodiment is between 1 and 5 mm, and the thicknesses of the upper surface layer 1 and the lower surface layer 4 are both between 0.01 and 0.05 mm. The thickness of the first foam layer 2 is between 0.1 and 0.5 mm, and the average diameter of the bubbles is between 0.03 and 0.08 mm. The thickness of the second foam layer 3 is between 0.78 and 3.9 mm, and the average diameter of the bubbles is between 0.3 and 0.8 mm.

[0025] The average density of the light diffusion plate according to the second embodiment is 0.3 to 0.85 g / cm 3The thickness can be controlled within a range between 0.01 and 0.15, the light transmittance can be controlled within a range between 40% and 60%, and the haze can be controlled within a range between 92% and 96%. Specifically, by adjusting the thickness or the diameter of the bubbles of the first foam layer 2 and the second foam layer 3, the average density, light transmittance, and haze of the light diffuser plate can be adjusted to obtain the desired diffuser plate. Table 2 shows the relationship between different thicknesses, average density, haze, and light transmittance of the light diffuser plate according to the second embodiment.

[0026] <Table 2: Haze and light transmittance of light diffusion plates with different total thicknesses and average densities according to Example 2> TIFF0007786686000002.tif88138

[0027] (Third Example) FIG. 3 is a schematic diagram showing the configuration of a lightweight foam structure for a light diffuser plate according to a second embodiment of the present invention. In this third embodiment, the four-layer structure of the light diffuser plate has been modified to a five-layer structure, with three foam layers placed between two upper and lower surface layers. The core layer has a two-layer structure consisting of a first foam layer 2 and a second foam layer 3 laminated thereon, resulting in a three-layer structure of second foam layer 3-first foam layer 2-second foam layer 3. More specifically, the total thickness of the light diffuser plate according to the third embodiment is in the range of 1 to 5 mm, and the thicknesses of the upper surface layer 1 and the lower surface layer 4 are both in the range of 0.01 to 0.05 mm. The thickness of the first foam layer 2 is in the range of 0.2 to 1 mm, and the average diameter of the air bubbles is in the range of 0.03 to 0.08 mm. The thickness of the second foam layer 3 is in the range of 0.39 to 1.95 mm, and the average diameter of the air bubbles is in the range of 0.3 to 0.8 mm.

[0028] The average density of the light diffusion plate according to the third embodiment is 0.3 to 0.85 g / cm 3The thickness can be controlled within a range between 0.01 and 0.15, the light transmittance can be controlled within a range between 40% and 60%, and the haze can be controlled within a range between 92% and 96%. Specifically, by adjusting the thickness or the diameter of the bubbles of the first foam layer 2 and the second foam layer 3, the average density, light transmittance, and haze of the light diffuser plate can be adjusted to obtain the desired foam light diffuser plate. Table 3 shows the relationship between different thicknesses, average density, haze, and light transmittance of the light diffuser plate according to the third embodiment.

[0029] Table 3: Haze and light transmittance of light diffusion plates with different total thicknesses and average densities according to this example TIFF0007786686000003.tif88138

[0030] The present invention further provides a method for manufacturing a lightweight foam structure for a light diffusion plate, which manufactures a four-layer or five-layer light diffusion plate by combining a distributor with a screw extruder or by in-mold compounding. The four-layer light diffusion plate has a sequentially connected upper surface layer 1, a first foam layer 2, a second foam layer 3, and a lower surface layer 4. The five-layer light diffusion plate has a sequentially connected upper surface layer 1, a first foam layer 2, a second foam layer 3, a first foam layer 2, and a lower surface layer 4, or a sequentially connected upper surface layer 1, a second foam layer 3, a first foam layer 2, a second foam layer 3, and a lower surface layer 4.

[0031] The surface layer of the light diffusion plate employs materials and techniques common in the art, and the raw material composition of the foam layer includes a high-polymer transparent material and a foaming agent. The high-polymer transparent material is one of polystyrene (PS), polypropylene (PP), polycarbonate (PC), or polyethylene terephthalate (PET). When the high-polymer transparent material is polystyrene, the raw material composition further includes a toughening agent SEBS, transparent TPE, or TPR. When the high-polymer transparent material is polycarbonate, the raw material composition further includes a toughening agent MBS. When the high-polymer transparent material is polypropylene or polyethylene terephthalate, no toughening agent is required. When the raw material composition of the first foam layer 2 and the second foam layer 3 includes a toughening agent, the toughening agent content is between 1 and 20 wt% of the raw material composition.

[0032] When the first foam layer 2 uses an expandable microsphere blowing agent or an endothermic and / or exothermic blowing agent with a particle size between 0.003 and 0.005 mm, the amount of the blowing agent is between 0.5 and 2 wt% of the raw materials for the first foam layer 2. When the first foam layer 2 uses an expandable microsphere blowing agent, a nucleating agent is not required. When the first foam layer 2 uses an endothermic and / or exothermic blowing agent, a nucleating agent is further used to induce the formation of a micropore structure with a pore size of less than 0.08 mm and control the pore size of the bubbles. The nucleating agent is calcium carbonate or silicon dioxide, and the amount of the nucleating agent is between 0.1 and 3 wt% of the raw materials for the first foam layer 2.

[0033] The second foam layer 3 employs an endothermic and / or exothermic foaming agent with a particle size ranging from 0.05 to 0.09 mm, and the amount of the foaming agent ranges from 0.7 to 6 wt% of the raw materials of the second foam layer 3. The pore size ranges from 0.3 to 0.8 mm, and no nucleating agent can be used in the second foam layer 3 to prevent the pore size from becoming small.

[0034] The endothermic blowing agent is sodium bicarbonate, and the exothermic blowing agent is azodicarbonamide.

[0035] The back pressure of the in-mold composite mold is in the range of 2 to 25 MPa, and the temperature of the mold is in the range of 160 to 230°C. Different pressures result in different rates of pressure reduction; as the pressure increases, the pressure reduction also increases, resulting in smaller bubble sizes. The difference in pressure can be used to adjust the bubble size. When the mold temperature is in the range of 160 to 230°C, suitable viscoelasticity is formed during processing of the material, and the desired bubble size can be achieved by adjusting the pressure reduction of the mold.

[0036] Three screw extruders are used as hosts, with No. 3 corresponding to the second foam layer 3, No. 1 corresponding to the upper surface layer 1 and lower surface layer 4, and No. 2 corresponding to the first foam layer 2. The layers are combined using one distributor, and the materials with different pore sizes extruded by the three screw extruders and the non-foamed surface layer obtain three different structural layers, which are then pressed by a flat die to form the three types of light diffusion plate layers with the structures shown in Figures 1, 2, and 3. Each of the three screw extruders includes seven heating areas, namely, a first area, a second area, a third area, a fourth area, a fifth area, a sixth area, and a seventh area, from the feed end to the discharge end. The heating temperature of the first area is in the range of 150 to 160°C, the heating temperature of the second area is in the range of 160 to 170°C, the heating temperature of the third area is in the range of 180 to 190°C, the heating temperature of the fourth area is in the range of 190 to 205°C, the heating temperature of the fifth area is in the range of 190 to 170°C, the heating temperature of the sixth area is in the range of 160 to 170°C, and the heating temperature of the seventh area is in the range of 150 to 160°C. The heating temperature of the filter area ranges between 150-160°C, the heating temperature of the distributor ranges between 150-160°C, and the heating temperature of the die head device ranges between 150-200°C (PC material is heated an additional 30°C on this basis).

[0037] In this embodiment, the foam layer is made of polystyrene and a reinforcing agent, SEBS, with the reinforcing agent added at a ratio of 1 to 20 wt% of the materials. The first foam layer 2 is made of an endothermic blowing agent, sodium bicarbonate, with a particle size of 0.003 to 0.005 mm, with the amount of the blowing agent being 0.5 to 2 wt% of the material. A silicon dioxide nucleating agent is used to induce the formation of a microporous structure with a pore size of less than 0.080 mm and control the pore size of the bubbles, with the amount of the nucleating agent being 0.1 to 3 wt% of the material. The second foam layer 3 is made of an exothermic blowing agent, azodicarbonamide, with a particle size of 0.05 to 0.09 mm, with the amount of the blowing agent being 0.7 to 6 wt% of the material. The pore diameter reaches 0.3 to 0.8 mm, and in order to prevent the pore diameter from becoming smaller, no nucleating agent can be used in the second foam layer 3.

[0038] A method for manufacturing a light diffusion plate according to an embodiment of the present invention includes the following steps. 1. Mix the ingredients for each layer according to the mixing ratio, mix evenly in a mixer, and then store. 2. Select a mold that corresponds to the 5-layer extrusion molding method, install the extrusion head, and inspect whether the extrusion equipment and each rotating part are complete. 3. Adjust the temperature control table to the operating temperature, heat the cylindrical mold, and maintain the temperature constant for 30 minutes after the temperature reaches the set value. 4. Of the three screw extruders, one corresponds to the upper surface layer 1 and the lower surface layer 4, one corresponds to the first foam layer 2 connected to the upper surface layer 1 and the lower surface layer 4, respectively, and one corresponds to the second foam layer 3. After uniform mixing, the mixed material for each layer is fed into the corresponding feed port. The filters of each extruder are replaced, the metering pumps are started in sequence, the screw motors are rotated, and parameters such as metering pump pressure, feed rate, and host rotation speed are set. The plastic material is plasticized as it passes through the cylinder and is then extruded by the extruder. The die lip is cleaned. Parameters such as the metering pump, main line speed, and pressure are adjusted, and extrusion begins. 5. The materials in the three screw extruders are melted and then extruded into a mold to compound them, and the composite plate material is extruded from the mold outlet to produce a five-layer light diffusion plate sheet material.

[0039] In this embodiment, the upper and lower surface layers are manufactured using materials and means commonly used in the art.

[0040] In this embodiment, the screw extruder for producing the first foam layer 2 includes seven heating zones, namely, zones 1, 2, 3, 4, 5, 6, and 7, from the feed end to the discharge end. The heating temperature of zone 1 is in the range of 150 to 160°C, the heating temperature of zone 2 is in the range of 160 to 170°C, the heating temperature of zone 3 is in the range of 180 to 190°C, the heating temperature of zone 4 is in the range of 190 to 205°C, the heating temperature of zone 5 is in the range of 190 to 170°C, the heating temperature of zone 6 is in the range of 160 to 170°C, and the heating temperature of zone 7 is in the range of 150 to 160°C. The heating temperature of zone 1 is in the range of 150 to 160°C, the heating temperature of zone 2 is in the range of 160 to 170°C, and the heating temperature of zone 7 is in the range of 150 to 160°C. The heating temperature of zone 1 is in the range of 150 to 160°C, the heating temperature of zone 1 is in the range of 150 to 160°C, and the heating temperature of zone 1 is in the range of 150 to 200°C. The screw extruder for producing the second foam layer 3 includes seven heating zones, from the feed end to the discharge end: first zone, second zone, third zone, fourth zone, fifth zone, sixth zone, and seventh zone. The heating temperature of the first zone is in the range of 150 to 160°C, the heating temperature of the second zone is in the range of 160 to 170°C, the heating temperature of the third zone is in the range of 180 to 190°C, the heating temperature of the fourth zone is in the range of 190 to 205°C, the heating temperature of the fifth zone is in the range of 190 to 170°C, the heating temperature of the sixth zone is in the range of 160 to 170°C, and the heating temperature of the seventh zone is in the range of 150 to 160°C. The heating temperature of the filter zone is in the range of 150 to 160°C, the heating temperature of the distributor is in the range of 150 to 160°C, and the heating temperature of the die head device is in the range of 150 to 200°C. The back pressure of the in-mold compounding method is in the range of 2 to 25 MPa, and the temperature of the mold is in the range of 160 to 230°C. When the temperature of the mold is in the range of 160 to 230°C, the material forms suitable viscoelasticity during processing, and in combination with the pressure drop of the mold, it is possible to obtain the desired pore size of the cells.

[0041] In an embodiment of the present invention, the first foam layer 2 can be replaced with a light diffusing agent. The light diffusing agent can be inorganic and / or organic. Inorganic light diffusing agents include nano-barium sulfate, calcium carbonate, silicon dioxide, etc., while organic light diffusing agents include acrylic, styrene monomer, acrylic resin, organosilicon particles, etc.

[0042] Compared with the prior art, the present invention has the following advantages: 1. The present invention improves the structure of the light diffusion plate by combining two types of foam layers: one with a small average bubble diameter and a thin foam layer, and the other with a large average bubble diameter and a thick foam layer. This ensures that the performance of the light diffusion plate reaches the level of the prior art while reducing its density to 0.3g / cm. 3 The conventional technology reduces the density to 0.85 g / cm 3 Compared to the previous model, the reduction is over 50%, which means that costs have clearly decreased and it has a clear advantage in market competition. 2. The present invention adjusts the average density, light transmittance, and haze of the light diffusion plate by adjusting the thickness of each of the first foam layer 2 and the second foam layer 3 or the average diameter of the bubbles thereof, and the average density of the light diffusion plate is set to 0.3 to 0.85 g / cm. 3 The light transmittance can be in the range of 40 to 60%, and the haze can be in the range of 92 to 96%.

[0043] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0044] 1 Upper surface layer 2. First foam layer 3 Second foam layer 4 Lower surface layer

Claims

1. A foam lightweight structure of a light diffusion plate, The light diffusion plate includes an upper surface layer, a first foam layer, a second foam layer, and a lower surface layer, which are connected in sequence; the thickness of the first foam layer is thinner than the thickness of the second foam layer; the average diameter of the cells in the first foam layer is smaller than the average diameter of the cells in the second foam layer; The average diameter of the cells in the first foam layer is in the range of 0.03 to 0.08 mm; The average diameter of the cells in the second foam layer is in the range of 0.3 to 0.8 mm. Lightweight foam structure for light diffusion panels.

2. The total thickness of the light diffusion plate is in the range of 1 to 5 mm, and the average density is 0.3 to 0.85 g / cm ３ 2. The light diffusing plate according to claim 1, wherein the foamed lightweight structure is in the range of 0.1 to 1.

0.

3. 3. The lightweight foam structure of claim 2, further comprising one first foam layer between the second foam layer and the lower surface layer.

4. 3. The lightweight foam structure of claim 2, further comprising one second foam layer between the upper surface layer and the first foam layer.

5. the thickness of each of the upper surface layer and the lower surface layer is in the range of 0.01 to 0.05 mm; the thickness of the first foam layer is in the range of 0.2 to 1 mm; 3. The lightweight foam structure of claim 2, wherein the thickness of the second foam layer is in the range of 0.78 to 3.9 mm.

6. the thickness of each of the upper surface layer and the lower surface layer is in the range of 0.01 to 0.05 mm; the thickness of the first foam layer is in the range of 0.1 to 0.5 mm; 4. The lightweight foam structure of claim 3, wherein the thickness of the second foam layer is in the range of 0.78 to 3.9 mm.

7. the thickness of each of the upper surface layer and the lower surface layer is in the range of 0.01 to 0.05 mm; the thickness of the first foam layer is in the range of 0.2 to 1 mm; 5. The lightweight foam structure of claim 4, wherein the thickness of the second foam layer is in the range of 0.39 to 1.95 mm.

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