Self-cleaning single-layer foaming diffusion plate and preparation method thereof

Abstract

The invention discloses a self-cleaning single-layer foaming diffusion plate and a preparation method thereof. The self-cleaning single-layer foaming diffusion plate is composed of GPPS resin, composite foaming agent master batch, a light diffusion agent, a whitening agent and an antioxidant 1010. Wherein the composite foaming agent master batch is prepared from polyethylene resin, sodium bicarbonate, sodium citrate, modified nano titanium dioxide, stearic acid, calcium stearate, an antioxidant 168, maleic anhydride grafted polyethylene and cellulose nanofibers; the formula and the process are improved, so that the optical performance and the mechanical performance of the single-layer foaming diffusion plate can be comparable with those of an existing three-layer GPPS foaming diffusion plate, and meanwhile the single-layer foaming diffusion plate has the self-cleaning capacity.

Description

Technical Field

[0001] The invention relates to the technical field of diffuser plate manufacturing, in particular to a self-cleaning single-layer foamed diffuser plate and a preparation method thereof. Background Art

[0002] Liquid crystal display technology has been widely infiltrated into various display devices, from mobile phones, tablets to computer monitors, TVs, etc. In order to present clear, realistic and glare-free images, the diffuser plate is required to effectively process the light of the backlight source to ensure that the light is evenly distributed on the screen, thereby improving the display effect. At present, the common diffusers on the market are mostly made of three-layer co-extrusion injection molding process to form three-layer diffusers with thickness specifications such as 1.0 / 1.2 / 1.5 / 2.0mm. However, as the thickness increases, the amount of material used increases, which not only leads to a significant increase in production costs, but also causes a corresponding increase in transportation costs. And as the thickness increases, more light will be absorbed and scattered in the process of passing through the diffuser plate, which will reduce the transmittance and affect the optical performance of the diffuser plate. In addition, the existing diffuser plate is also faced with the problem of electrostatic adsorption of dust in practical applications. Due to the effect of electrostatics, a large amount of dust will adhere to and accumulate on the surface of the diffuser plate, which not only reduces the optical performance of the diffuser plate, but also makes the light scattering effect worse and the lighting uniformity decrease. It also affects its heat dissipation performance and greatly shortens the service life of the diffuser plate. To solve these problems, a single-layer foam diffuser plate came into being. However, the existing single-layer foam diffuser has far inferior optical and mechanical properties to the three-layer foam diffuser, and cannot meet high-standard usage requirements. At the same time, the self-cleaning problem also plagues the development of single-layer foam diffuser, and the adhesion of pollutants such as dust will also reduce its performance. In summary, the development of a single-layer foam diffuser that can achieve or even exceed the three-layer foam diffuser in terms of optical and mechanical properties and has a self-cleaning function is of great significance for promoting the development of liquid crystal display, LED lighting, and imaging systems. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a self-cleaning single-layer foaming diffusion plate, which is composed of the following components in parts by mass: 85-92 parts of GPPS resin, 4.94-5.76 parts of composite foaming agent masterbatch, 3-9 parts of light diffuser, 0.01-0.09 parts of brightener, and 0.05-0.15 parts of antioxidant 1010;

[0004] The composite foaming agent masterbatch is composed of the following components in parts by mass:

[0005] 38-68 parts of polyethylene resin, 5-9 parts of sodium bicarbonate, 6-8 parts of sodium citrate, 10-20 parts of modified nano titanium dioxide, 7.2-11.2 parts of stearic acid, 0.4-1.6 parts of calcium stearate, 0.04-0.08 parts of antioxidant 168, 0.36-1.12 parts of maleic anhydride grafted polyethylene, and 3-11 parts of cellulose nanofibers. Sodium bicarbonate and sodium citrate synergistically decompose and produce gas when heated, and these gases will form uniformly distributed micropores in the GPPS matrix. Stearic acid and calcium stearate serve as lubricants and stabilizers to help improve the fluidity of the components of the diffusion plate during processing.

[0006] Preferably, the light diffuser is nano-silicon dioxide.

[0007] Preferably, the whitening agent is titanium dioxide.

[0008] The present invention also provides a method for preparing a self-cleaning single-layer foaming diffusion plate, comprising the following steps:

[0009] preparing composite foaming agent masterbatch;

[0010] 85-92 parts of the GPPS resin, 4.94-5.76 parts of composite foaming agent masterbatch, 3-9 parts of light diffusing agent, 0.01-0.09 parts of brightener, and 0.05-0.15 parts of antioxidant are pre-mixed by stirring for 3-7 minutes to obtain a mixture a;

[0011] The mixture a is fed into the feed end of the twin-screw extruder for heating and pressurizing and extruding to the extrusion template, and cast and cooled for 3 to 5 minutes to form a blank material that has not been completely cooled and shaped;

[0012] The temperature of each zone of the twin-screw extruder is as follows: the temperature of zone 1 is 180-190°C, the temperature of zone 2 is 190-200°C, the temperature of zone 3 is 210-220°C, the temperature of zone 4 is 210-220°C, the temperature of zone 5 is 225-235°C, the temperature of zone 6 is 215-225°C, the temperature of zone 7 is 210-220°C, and the temperature of the die head is 205-215°C; the production speed is 300-320kg / h; if the production speed is too slow, the material stays in the twin-screw extruder for too long, which will cause the sodium bicarbonate to foam prematurely; if the production speed is too fast, the shear force of the screw on the material is too large, which will cause the material temperature to rise locally, which also causes the sodium bicarbonate to foam prematurely. It is more appropriate to control the production speed at 300-320kg / h. The processing temperature of each section of the twin-screw extruder should be lower than the decomposition temperature of the sodium bicarbonate in the composite foaming agent masterbatch, and at the same time, the material must have good fluidity. The processing temperature of each section and the die head temperature are more appropriate.

[0013] The above-mentioned embryonic sheet material which has not been completely cooled and shaped is placed in the upper and lower electromagnetic heating rollers for hot pressing and ironing to obtain a product sheet material with relatively smooth upper and lower surfaces, and then enters the transmission device for natural cooling to obtain the finished product.

[0014] Preferably, the preparation of the composite foaming agent masterbatch comprises the following steps:

[0015] Preparation of modified nano titanium dioxide;

[0016] The above-mentioned 38-68 parts of polyethylene resin, 5-9 parts of sodium bicarbonate, 6-8 parts of sodium citrate, 10-20 parts of modified nano titanium dioxide, 7.2-11.2 parts of stearic acid, 0.4-1.6 parts of calcium stearate, 0.04-0.08 parts of antioxidant, 0.36-1.12 parts of maleic anhydride grafted polyethylene, and 3-11 parts of cellulose nanofibers are added into a blender and mixed well, and then extruded and granulated by a twin-screw extruder.

[0017] Preferably, the preparation of modified nano titanium dioxide comprises the following steps:

[0018] 7-9 parts of γ-aminopropyltriethoxysilane, 5-9 parts of polypyrrole, and 32-38 parts of nano titanium dioxide powder are dissolved in 38-52 parts of anhydrous ethanol and stirred for 20-40 minutes, and then 4-6 parts of nano silver are added in batches and intermittently ultrasonicated for 20-40 minutes. The ultrasonic power is 50-150W, that is, the ultrasonication is stopped for 5 minutes for 5 minutes, and the precipitate is collected by centrifugation, and the precipitate is washed with anhydrous ethanol for 3-5 times. The washed precipitate is dried at 40-60°C for 2-4 hours to obtain modified nano titanium dioxide.

[0019] Preferably, in the process of preparing the composite foaming agent masterbatch, the speed of the mixer is 500-1000 r / min, the speed of the twin-screw is 40-60 r / min, and the extrusion temperature of the twin-screw is 130-150°C.

[0020] Preferably, during the preparation of modified nano-titanium dioxide, the speed of the stirrer is 500-1000 r / min.

[0021] Preferably, the temperature of the upper and lower electromagnetic heating rollers for hot pressing and ironing is 190-220°C.

[0022] The beneficial effects are:

[0023] The present application optimizes and improves the single-layer foam diffuser plate from the following aspects so that it has optical and mechanical properties comparable to those of a three-layer foam diffuser plate while also having self-cleaning capabilities.

[0024] In terms of technology, in the process of preparing the foamed diffusion plate, the components of the diffusion plate are heated and pressurized by a twin-screw extruder, and the composite foaming agent masterbatch quickly decomposes at the moment of extrusion to produce gas to form a bubble structure. The bubbles can be initially closed by cast cooling, and the embryonic plate that has not been completely cooled and shaped is placed in the upper and lower opposing electromagnetic heating rollers for hot pressing and ironing to obtain a product plate with relatively smooth upper and lower surfaces. The smoother the upper and lower surfaces of the product plate, the smaller the energy loss when light penetrates the diffusion plate, the smaller the deformation caused to the internal bubbles, and the better the light penetration and diffusion of the foamed diffusion plate. In addition, the embryonic plate becomes more compact after hot pressing by the upper and lower opposing electromagnetic heating rollers, and a crusting layer is formed on the upper and lower surfaces after hot pressing to support the middle tissue of the diffusion plate, so as to achieve the purpose of improving the mechanical properties of the diffusion plate.

[0025] In terms of formulation, since sodium bicarbonate is sensitive to temperature, if sodium bicarbonate is directly added to GPPS resin to be processed into a diffusion plate, the high temperature may cause sodium bicarbonate to decompose prematurely. Therefore, the present application does not directly add sodium bicarbonate, but first makes sodium bicarbonate into a composite foaming agent masterbatch by selecting polyethylene resin as a carrier resin to improve the more uniform dispersion of sodium bicarbonate in the final resin mixture so as to form a uniform pore structure; at the same time, the preparation of the composite foaming agent masterbatch can also improve the thermal stability of sodium bicarbonate, so that sodium bicarbonate can remain stable at the processing temperature and can quickly decompose to produce gas when needed, thereby ensuring the foaming effect of sodium bicarbonate and improving the optical properties of the diffusion plate.

[0026] In order to further improve the performance of composite foaming agent masterbatch, modified nano titanium dioxide and cellulose nanofibers are selected as nucleating agents when preparing composite foaming agent masterbatch, which can make the diffusion plate form a smaller and more uniform bubble structure, thereby increasing the foaming ratio and reducing defects. The addition of cellulose nanofibers can significantly improve the mechanical properties of the diffusion plate, such as tensile strength, bending strength and impact strength, making the produced diffusion plate more durable and more stable in structure; the added cellulose nanofibers can also prevent the modified nano titanium dioxide from agglomerating and improve the foaming effect, and the modified nano titanium dioxide can support the pore wall, thereby achieving the improvement of the optical and mechanical properties of the diffusion plate at the same time; and the cellulose nanofibers can also undergo physical crosslinking with the GPPS resin to improve the melt fluidity of the GPPS resin. On the other hand, the cellulose nanofibers are rich in hydroxyl groups and can undergo esterification reaction with the anhydride groups in the maleic anhydride grafted polyethylene. At the same time, the cellulose nanofibers can form hydrogen bonds with the functional groups in the GPPS resin, and the anhydride groups in the maleic anhydride grafted polyethylene react with the hydroxyl groups in the GPPS resin to form chemical bonds. On the other hand, maleic anhydride grafted polyethylene can react with the active sites of polyethylene resin, so that the cellulose nanofibers and maleic anhydride grafted polyethylene work synergistically to improve the compatibility of the composite foaming agent masterbatch with the GPPS resin, so that the composite foaming agent masterbatch can be more evenly dispersed in the blending system, and the optical and mechanical properties of the diffuser are improved; and the modified nano titanium dioxide, in addition to being a nucleating agent to promote bubble formation, can also work together with the light diffuser of the diffuser to further optimize the light diffusion effect of the diffuser, so that the light can be more evenly and softly transmitted or reflected. The most important role of the modified nano titanium dioxide is that it has photocatalytic activity to decompose organic pollutants, and can also improve the conductivity of the composite foaming agent masterbatch and dissipate static electricity, so that the diffuser has self-cleaning ability; finally, the present application cleverly constructs a double-layer antioxidant system for the diffuser when preparing the composite foaming agent masterbatch, the antioxidant 1010 captures free radicals to prevent chain reactions, and the antioxidant 168 decomposes peroxides to reduce the generation of free radicals, thereby greatly extending the service life of the diffuser.

[0027] Thus, the present application makes improvements in formulation and process, thereby greatly improving the optical and mechanical properties of the diffuser plate, and also provides self-cleaning capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 The microstructure of the self-cleaning single-layer foamed diffuser plate prepared in Example 2 of the present application was observed by scanning electron microscopy (SEM). DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0031] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0032] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0033] Source of raw materials:

[0034] GPPS resin (CAS No. 9003-53-6, model PS525) and polyethylene resin (CAS No. 9002-88-4, model HDPE 5000S) were purchased from Jining Tangyi Chemical Co., Ltd.;

[0035] Nano-silicon dioxide was purchased from Shanghai Huijingya Nano New Materials Co., Ltd.;

[0036] Titanium dioxide (particle size 200-500 nm) was purchased from Suzhou Shuoke New Materials Co., Ltd.;

[0037] Antioxidant 1010 and antioxidant 168 were purchased from Henan Wanshan New Materials Technology Co., Ltd.;

[0038] Sodium bicarbonate and sodium citrate were purchased from Langfang Qianyao Technology Co., Ltd.

[0039] Stearic acid was purchased from Langfang Pengcai Fine Chemical Co., Ltd.

[0040] Calcium stearate, purchased from Henan Xinzhiyuan Chemical Products Co., Ltd.;

[0041] Maleic anhydride grafted polyethylene was purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd.;

[0042] Cellulose nanofibers were purchased from Hubei Shineng Chemical Technology Co., Ltd.;

[0043] γ-Aminopropyltriethoxysilane was purchased from Hangzhou Jessica Chemical Co., Ltd.;

[0044] Polypyrrole was purchased from Hubei Nona Technology Co., Ltd.;

[0045] Nano-titanium dioxide (particle size 1-100 nm) was purchased from Guangzhou Yinuo Chemical Technology Co., Ltd.

[0046] Anhydrous ethanol was purchased from Shanghai Kelong Chemical Co., Ltd.;

[0047] Nanosilver was purchased from Hebei Senade Nanomaterial Technology Co., Ltd.

[0048] The remaining reagents are commercially available.

[0049] Example 1

[0050] The present embodiment provides a self-cleaning single-layer foamed diffuser plate, which is composed of the following components in parts by mass: 92 parts of GPPS resin, 4.94 parts of composite foaming agent masterbatch, 3 parts of light diffuser, 0.01 parts of brightener, and 0.05 parts of antioxidant 1010; the above-mentioned composite foaming agent masterbatch is composed of the following components in parts by mass: 68 parts of polyethylene resin, 5 parts of sodium bicarbonate, 6 parts of sodium citrate, 10 parts of modified nano titanium dioxide, 7.2 parts of stearic acid, 0.4 parts of calcium stearate, 0.04 parts of antioxidant 168, 0.36 parts of maleic anhydride grafted polyethylene, and 3 parts of cellulose nanofibers, wherein the above-mentioned light diffuser is specifically nano silicon dioxide, and the brightener is specifically titanium dioxide.

[0051] A method for preparing a self-cleaning single-layer foaming diffusion plate comprises the following steps:

[0052] The preparation of modified nano titanium dioxide comprises the following steps:

[0053] 7 parts of γ-aminopropyltriethoxysilane, 5 parts of polypyrrole, and 32 parts of nano titanium dioxide powder were dissolved in 52 parts of anhydrous ethanol and stirred for 20 minutes at a stirring speed of 500 r / min, and then 4 parts of nano silver were added in batches and intermittently ultrasonicated for 20 minutes at an ultrasonic power of 50 W, i.e., ultrasonicated for 5 minutes and rested for 5 minutes, and the precipitate was collected by centrifugation, and the precipitate was washed 3 times with anhydrous ethanol, and the washed precipitate was dried at 40° C. for 2 hours to obtain modified nano titanium dioxide;

[0054] The preparation of composite foaming agent masterbatch comprises the following steps:

[0055] The above 68 parts of polyethylene resin, 5 parts of sodium bicarbonate, 6 parts of sodium citrate, 10 parts of modified nano titanium dioxide, 7.2 parts of stearic acid, 0.4 parts of calcium stearate, 0.04 parts of antioxidant 168, 0.36 parts of maleic anhydride grafted polyethylene, and 3 parts of cellulose nanofibers were added into a blender and mixed well, and then extruded and granulated by a twin-screw extruder, wherein the blender speed was 500 r / min, the twin-screw speed was 40 r / min, and the twin-screw extrusion temperature was 130°C;

[0056] The preparation of the foaming diffuser plate comprises the following steps:

[0057] 92 parts of the GPPS resin, 4.94 parts of composite foaming agent masterbatch, 3 parts of light diffuser, 0.01 parts of brightener, and 0.05 parts of antioxidant 1010 were pre-mixed by stirring for 3 minutes to obtain a mixture a;

[0058] The mixture a is fed into the feeding end of the twin-screw extruder for heating and pressurizing and extruding to the extrusion template, and cast and cooled for 3 minutes to form a embryonic sheet material that has not been completely cooled and shaped;

[0059] The temperature of each zone of the twin-screw extruder is: the temperature of zone 1 is 180℃, the temperature of zone 2 is 190℃, the temperature of zone 3 is 210℃, the temperature of zone 4 is 210℃, the temperature of zone 5 is 225℃, the temperature of zone 6 is 215℃, the temperature of zone 7 is 210℃, and the temperature of the die head is 205℃; the production speed is 300kg / h;

[0060] The above-mentioned embryonic sheet material that has not been completely cooled and shaped is placed in the upper and lower electromagnetic heating rollers for hot pressing and ironing to obtain a product sheet material with relatively smooth upper and lower surfaces. After that, it enters the transmission device and is naturally cooled to obtain the finished product. The temperature of the upper and lower electromagnetic heating rollers for hot pressing and ironing is 190°C.

[0061] Example 2

[0062] The present embodiment provides a self-cleaning single-layer foamed diffuser plate, which is composed of the following components in parts by mass: 88.5 parts of GPPS resin, 5.35 parts of composite foaming agent masterbatch, 6 parts of light diffuser, 0.05 parts of brightener, and 0.1 parts of antioxidant 1010; the above-mentioned composite foaming agent masterbatch is composed of the following components in parts by mass: 53 parts of polyethylene resin, 7 parts of sodium bicarbonate, 7 parts of sodium citrate, 15 parts of modified nano titanium dioxide, 9.2 parts of stearic acid, 1 part of calcium stearate, 0.06 parts of antioxidant 168, 0.74 parts of maleic anhydride grafted polyethylene, and 7 parts of cellulose nanofibers, wherein the above-mentioned light diffuser is specifically nano silicon dioxide, and the brightener is specifically titanium dioxide.

[0063] A method for preparing a self-cleaning single-layer foaming diffusion plate comprises the following steps:

[0064] The preparation of modified nano titanium dioxide comprises the following steps:

[0065] 8 parts of γ-aminopropyltriethoxysilane, 7 parts of polypyrrole, and 35 parts of nano titanium dioxide powder were dissolved in 45 parts of anhydrous ethanol and stirred for 30 minutes, with the stirring speed of the stirrer being 750 r / min, and then 5 parts of nano silver were added in batches and intermittently ultrasonicated for 30 minutes, with the ultrasonic power being 100 W, that is, ultrasonicating for 5 minutes and stopping for 5 minutes, and the precipitate was collected by centrifugation, and the precipitate was washed with anhydrous ethanol for 4 times, and the washed precipitate was dried at 50° C. for 3 hours to obtain modified nano titanium dioxide;

[0066] The preparation of composite foaming agent masterbatch comprises the following steps:

[0067] 53 parts of polyethylene resin, 7 parts of sodium bicarbonate, 7 parts of sodium citrate, 15 parts of modified nano titanium dioxide, 9.2 parts of stearic acid, 1 part of calcium stearate, 0.06 parts of antioxidant 168, 0.74 parts of maleic anhydride grafted polyethylene, and 7 parts of cellulose nanofibers were added into a blender and mixed well, and then extruded and granulated using a twin-screw extruder, wherein the blender speed was 750 r / min, the twin-screw speed was 50 r / min, and the twin-screw extrusion temperature was 140°C;

[0068] The preparation of the foaming diffuser plate comprises the following steps:

[0069] 88.5 parts of the GPPS resin, 5.35 parts of the composite foaming agent masterbatch, 6 parts of the light diffuser, 0.05 parts of the brightener, and 0.1 parts of the antioxidant 1010 were pre-mixed by stirring for 5 minutes to obtain a mixture a;

[0070] The mixture a is fed into the feeding end of the twin-screw extruder for heating and pressurizing and extruding to the extrusion template, and cast and cooled for 4 minutes to form a embryonic sheet material that has not been completely cooled and shaped;

[0071] The temperature of each zone of the twin-screw extruder is: the temperature of zone 1 is 185℃, the temperature of zone 2 is 195℃, the temperature of zone 3 is 215℃, the temperature of zone 4 is 215℃, the temperature of zone 5 is 230℃, the temperature of zone 6 is 220℃, the temperature of zone 7 is 215℃, and the temperature of the die head is 210℃; the production speed is 310kg / h;

[0072] The above-mentioned embryonic sheet material that has not been completely cooled and shaped is placed in the upper and lower pressing electromagnetic heating rollers for hot pressing and ironing to obtain a product sheet material with relatively smooth upper and lower surfaces. After that, it enters the transmission device and is naturally cooled to obtain the finished product. The temperature of the upper and lower pressing electromagnetic heating rollers for hot pressing and ironing is 205℃.

[0073] Example 3

[0074] The present embodiment provides a self-cleaning single-layer foamed diffuser plate, which is composed of the following components in parts by mass: 85 parts of GPPS resin, 5.76 parts of composite foaming agent masterbatch, 9 parts of light diffuser, 0.09 parts of brightener, and 0.15 parts of antioxidant 1010; the above-mentioned composite foaming agent masterbatch is composed of the following components in parts by mass: 38 parts of polyethylene resin, 9 parts of sodium bicarbonate, 8 parts of sodium citrate, 20 parts of modified nano titanium dioxide, 11.2 parts of stearic acid, 1.6 parts of calcium stearate, 0.08 parts of antioxidant 168, 1.12 parts of maleic anhydride grafted polyethylene, and 11 parts of cellulose nanofibers, wherein the above-mentioned light diffuser is specifically nano silicon dioxide, and the brightener is specifically titanium dioxide.

[0075] A method for preparing a self-cleaning single-layer foaming diffusion plate comprises the following steps:

[0076] The preparation of modified nano titanium dioxide comprises the following steps:

[0077] 9 parts of γ-aminopropyltriethoxysilane, 9 parts of polypyrrole, and 38 parts of nano titanium dioxide powder were dissolved in 38 parts of anhydrous ethanol and stirred for 40 minutes, with the stirring speed of the stirrer being 1000 r / min, and then 6 parts of nano silver were added in batches and intermittently ultrasonicated for 40 minutes, with the ultrasonic power being 150 W, that is, ultrasonicated for 5 minutes and rested for 5 minutes, and the precipitate was collected by centrifugation, and the precipitate was washed with anhydrous ethanol for 5 times, and the washed precipitate was dried at 60° C. for 4 hours to obtain modified nano titanium dioxide;

[0078] The preparation of composite foaming agent masterbatch comprises the following steps:

[0079] 38 parts of polyethylene resin, 9 parts of sodium bicarbonate, 8 parts of sodium citrate, 20 parts of modified nano titanium dioxide, 11.2 parts of stearic acid, 1.6 parts of calcium stearate, 0.08 parts of antioxidant 168, 1.12 parts of maleic anhydride grafted polyethylene, and 11 parts of cellulose nanofibers were added into a blender and mixed well, and then extruded and granulated using a twin-screw extruder, wherein the blender speed was 1000 r / min, the twin-screw speed was 60 r / min, and the twin-screw extrusion temperature was 150°C;

[0080] The preparation of the foaming diffuser plate comprises the following steps:

[0081] 85 parts of the GPPS resin, 5.76 parts of composite foaming agent masterbatch, 9 parts of light diffuser, 0.09 parts of brightener, and 0.15 parts of antioxidant 1010 were pre-mixed by stirring for 7 minutes to obtain a mixture a;

[0082] The mixture a is fed into the feeding end of the twin-screw extruder for heating and pressurizing and extruding to the extrusion template, and cast and cooled for 5 minutes to form a embryonic sheet material that has not been completely cooled and shaped;

[0083] The temperature of each zone of the twin-screw extruder is: the temperature of zone 1 is 190℃, the temperature of zone 2 is 200℃, the temperature of zone 3 is 220℃, the temperature of zone 4 is 220℃, the temperature of zone 5 is 235℃, the temperature of zone 6 is 225℃, the temperature of zone 7 is 220℃, and the temperature of the die head is 215℃; the production speed is 320kg / h;

[0084] The above-mentioned embryonic sheet material that has not been completely cooled and shaped is placed in the upper and lower pressing electromagnetic heating rollers for hot pressing and ironing to obtain a product sheet material with relatively smooth upper and lower surfaces. After that, it enters the transmission device and is naturally cooled to obtain the finished product. The temperature of the upper and lower pressing electromagnetic heating rollers for hot pressing and ironing is 220℃.

[0085] Comparative Example 1

[0086] The difference between this comparative example and Example 2 is that 5.35 parts of the prepared composite foaming agent masterbatch are premixed with 88.5 parts of GPPS resin, 6 parts of light diffusers, 0.05 parts of brighteners, and 0.1 parts of antioxidant 1010 for 5 minutes to obtain a mixture a; the mixture a is put into the feed end of a twin-screw extruder for heating and pressurizing and extruding to an extrusion template, and then directly air-cooled and shaped to obtain a finished product, and the remaining steps are the same as those in Example 2.

[0087] Comparative Example 2

[0088] The difference between this comparative example and Example 2 is that 5.35 parts of sodium bicarbonate powder are used to replace 5.35 parts of composite foaming agent masterbatch, and the other ingredients and experimental steps are the same as those in Example 2.

[0089] Comparative Example 3

[0090] The difference between this comparative example and Example 2 is that 15 parts of nano titanium dioxide are used to replace 15 parts of modified nano titanium dioxide, and the other components and experimental steps are the same as those in Example 2.

[0091] Comparative Example 4

[0092] The difference between this comparative example and Example 2 is that the modified nano titanium dioxide is increased from 15 parts to 22 parts, and cellulose nanofibers are not added. The other components and experimental steps are the same as those in Example 2.

[0093] Comparative Example 5

[0094] The difference between this comparative example and Example 2 is that the modified nano titanium dioxide is increased from 15 parts to 15.74 parts, and maleic anhydride grafted polyethylene is not added. The other components and experimental steps are the same as those in Example 2.

[0095] Comparative Example 6

[0096] This comparative example is a three-layer GPPS foam diffusion plate with a thickness of 2.0 mm, purchased from Changzhou Shunweier Material Technology Co., Ltd.

[0097] The diffuser plates prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were tested.

[0098] Test method:

[0099] Both transmittance and haze are tested by a haze meter according to ASTM D1003 standard; transmittance is defined as the ratio of transmitted light to incident light; haze is the percentage of light transmittance that deviates from the incident direction due to scattering when the transmitted light passes through the sample;

[0100] The center brightness and average brightness are tested according to GY / T 326-2019 standard;

[0101] Heat deformation temperature is tested according to ASTM D648 standard;

[0102] Impact strength is tested according to ASTM D256 standard;

[0103] The tensile strength test analysis was carried out in accordance with GB / T 1040.1-2006 using a universal material testing machine;

[0104] The bending strength is measured using a universal material testing machine in accordance with GB / T142082-2009;

[0105] The test results are shown in Table 1.

[0106] Table 1 Test results of optical properties and mechanical properties of diffuser

[0107]

[0108] The self-cleaning performance test uses a combination of contact angle test and photocatalytic degradation experiment. The specific test steps are as follows: first, the contact angle of water droplets on the surface of the diffuser is measured using a contact angle meter. Then, a methylene blue solution is applied to the surface of the diffuser and exposed to ultraviolet light (365nm, intensity 2mW / cm 2 ) The degradation was observed. The static elimination performance test method was carried out in accordance with the national standard "Electrostatics Part 2-3: Test Method for Resistance and Resistivity of Antistatic Solid Plane Materials". The test results are shown in Table 2.

[0109] Table 2 Diffusion plate self-cleaning performance test results

[0110] project Water contact angle (°) Methylene blue degradation rate (%, 2h) Surface resistivity (Ω / sq) Example 1 8.1 92.3 <![CDATA[1.08*10 8 ]]> Example 2 7.9 95.1 <![CDATA[1.02*10 8 ]]> Example 3 8.2 94.6 <![CDATA[1.11*10 8 ]]> Comparative Example 1 7.8 90.8 <![CDATA[1.06*10 8 ]]> Comparative Example 2 11.6 56.9 <![CDATA[2.96*10 13 ]]> Comparative Example 3 8.6 91.8 <![CDATA[2.33*10 13 ]]> Comparative Example 4 9.4 76.5 <![CDATA[1.85*10 8 ]]> Comparative Example 5 9.7 68.9 <![CDATA[2.27*10 8 ]]> Comparative Example 6 12.9 52.3 <![CDATA[3.16*10 13 ]]>

[0111] From the experimental data in Table 1, it can be seen that the optical properties and mechanical properties of the single-layer foamed diffuser plates prepared in each embodiment of the present application are excellent. Compared with the experimental data of Comparative Example 6, it is found that the optical properties and mechanical properties of each embodiment of the present application are comparable to the existing three-layer GPPS foamed diffuser plate, among which Example 2 performs the best and can be regarded as the best embodiment of the present invention. Its transmittance and haze both reach more than 70%, the center brightness is as high as 1968, and the average brightness also reaches 1723, indicating that the diffuser plate achieves efficient light diffusion effect while ensuring a high transmittance, and can provide high-quality lighting effects. On the other hand, its impact strength reaches 70Kg / cm 2 The above means that the diffuser plate can withstand a large external impact without being easily broken. The bending strength of more than 110MPa means that the diffuser plate can withstand a certain bending stress without obvious deformation or fracture. The tensile strength of 180MPa means that the diffuser plate is not easily torn when subjected to tension. This result fully proves the excellent performance of the diffuser plate of the present invention in terms of optical properties and mechanical properties. Figure 1 It can also be seen that the diffuser plate prepared in Example 2 has uniform and dense pores and excellent foaming effect. From Table 2, it can be seen that Examples 1 to 3 all exhibit excellent self-cleaning performance, with water contact angles less than 10°, methylene blue degradation rates of more than 90%, and surface resistivity of 10 8 Ω, has good static dissipation ability and exhibits excellent self-cleaning effect.

[0112] Continuing to analyze Table 1, it can be found that in Comparative Example 1, the steps of casting cooling and hot pressing and ironing using upper and lower electromagnetic heating rollers are omitted, and the optical and mechanical properties of the diffuser plate are significantly reduced after the diffuser plate is directly prepared according to the ordinary process. This may be because the diffuser plate prepared by the ordinary process has been cooled and shaped before the bubbles on the surface have been closed, resulting in large energy loss when light penetrates the diffuser plate, and the diffusion property of the foamed diffuser plate to light penetration becomes poor. Moreover, without hot pressing and ironing with upper and lower electromagnetic heating rollers, no crust is formed on the surface of the diffuser plate, which cannot support the middle tissue of the diffuser plate, thereby causing the mechanical properties of the diffuser plate to deteriorate. In Comparative Example 2, sodium bicarbonate powder is directly substituted for the composite foaming agent masterbatch. It can be found that the optical and mechanical properties of the diffusion plate are also deteriorated, and the pore diameter is larger. This may be because the processing temperature of GPPS resin is high, while the decomposition temperature of sodium bicarbonate is relatively low. Directly adding sodium bicarbonate to GPPS resin to process it into a diffusion plate causes sodium bicarbonate to decompose prematurely. Although the gas production of sodium bicarbonate powder is large, the dispersion of sodium bicarbonate powder in GPPS resin is poor, resulting in poor foaming quality and failure to form a uniform small pore structure. In Comparative Example 3, nano titanium dioxide is used to replace modified nano titanium dioxide. It can be found that the optical and mechanical properties of the diffusion plate are almost the same as those of the embodiment, but the self-cleaning performance is significantly reduced. According to the national standard "Electrostatics Part 2-3: Test Method for Resistance and Resistivity of Antistatic Solid Planar Materials", it is generally believed that the surface resistivity is less than 10 11 The material with a surface resistivity of 10Ω / sq has good electrostatic dissipation performance, while the surface resistivity of comparative example 3 has reached 10 13Ω / sq, this may be because the foaming agent masterbatch prepared from ordinary nano-titanium dioxide used in Comparative Example 3 does not have conductivity. In addition, Comparative Examples 2 and 6 also have the phenomenon of significantly reduced self-cleaning performance, which just proves that the lack of modified nano-titanium dioxide will indeed cause the diffusion plate to lose its self-cleaning ability. Continuing to analyze Table 1, it can be found that the optical properties and mechanical properties of the diffusion plate in Comparative Example 4 are reduced after the lack of cellulose nanofibers, indicating that the addition of cellulose nanofibers can indeed significantly improve the tensile strength, bending strength and impact strength of the diffusion plate and improve the optical properties of the diffusion plate. This may be because cellulose nanofibers can be used as nucleating agents to increase the foaming ratio and reduce defects on the one hand, and on the other hand, they can avoid the agglomeration of modified nano-titanium dioxide and improve the foaming effect. On the other hand, they can be physically cross-linked or chemically bonded with the GPPS resin to improve the melt fluidity of the GPPS resin and improve the composite foaming agent masterbatch and Compatibility of GPPS resin; Continuing to analyze Table 1, it can be found that after the maleic anhydride grafted polyethylene is not added to the comparative example 5, the optical properties and mechanical properties of the diffuser plate are reduced. This may be because the maleic anhydride grafted polyethylene can react with the cellulose nanofibers by esterification on the one hand, and can chemically bond with the GPPS resin on the other hand, and can also react with the active sites of the polyethylene resin on the other hand. By adding maleic anhydride grafted polyethylene, it can synergistically improve the compatibility of the composite foaming agent masterbatch with the GPPS resin with the cellulose nanofibers, and comprehensively improve the optical properties and mechanical properties of the diffuser plate.

[0113] In summary, the present application provides a self-cleaning single-layer foam diffuser plate. By improving the formula and process, the optical and mechanical properties of the single-layer foam diffuser plate are comparable to those of the existing three-layer GPPS foam diffuser plate, while also having self-cleaning capabilities.

[0114] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A self-cleaning single-layer foam diffuser plate, characterized in that: The composition is composed of the following components in parts by mass: 85-92 parts of GPPS resin, 4.94-5.76 parts of composite foaming agent masterbatch, 3-9 parts of light diffuser, 0.01-0.09 parts of brightener, and 0.05-0.15 parts of antioxidant 1010; The composite foaming agent masterbatch is composed of the following components in parts by mass: 38-68 parts of polyethylene resin, 5-9 parts of sodium bicarbonate, 6-8 parts of sodium citrate, 10-20 parts of modified nano titanium dioxide, 7.2-11.2 parts of stearic acid, 0.4-1.6 parts of calcium stearate, 0.04-0.08 parts of antioxidant 168, 0.36-1.12 parts of maleic anhydride grafted polyethylene, and 3-11 parts of cellulose nanofibers.

2. The self-cleaning single-layer foam diffuser plate according to claim 1, characterized in that: The light diffusing agent is nano silicon dioxide.

3. The self-cleaning single-layer foam diffuser plate according to claim 1, characterized in that: The whitening agent is titanium dioxide.

4. The method for preparing a self-cleaning single-layer foamed diffuser plate according to claim 1, characterized in that: The following steps are involved: preparing the composite foaming agent masterbatch; 85-92 parts of GPPS resin, 4.94-5.76 parts of composite foaming agent masterbatch, 3-9 parts of light diffusing agent, 0.01-0.09 parts of brightener, and 0.05-0.15 parts of antioxidant 1010 are pre-mixed by stirring for 3-7 minutes to obtain a mixture a; The mixture a is fed into the feed end of the twin-screw extruder for heating and pressurizing and extruding to the extrusion template, and cast and cooled for 3 to 5 minutes to form a blank material that has not been completely cooled and shaped; The temperature of each zone of the twin-screw extruder is as follows: the temperature of zone 1 is 180-190°C, the temperature of zone 2 is 190-200°C, the temperature of zone 3 is 210-220°C, the temperature of zone 4 is 210-220°C, the temperature of zone 5 is 225-235°C, the temperature of zone 6 is 215-225°C, the temperature of zone 7 is 210-220°C, and the temperature of the die head is 205-215°C; the production speed is 300-320kg / h; The embryonic sheet material which has not been completely cooled and shaped is placed in the upper and lower electromagnetic heating rollers for hot pressing and ironing to obtain a product sheet material with relatively smooth upper and lower surfaces, and then enters the transmission device for natural cooling to obtain a finished product.

5. The method for preparing a self-cleaning single-layer foamed diffuser plate according to claim 4, characterized in that: The preparation of the composite foaming agent masterbatch comprises the following steps: preparing the modified nano titanium dioxide; 38 to 68 parts of polyethylene resin, 5 to 9 parts of sodium bicarbonate, 6 to 8 parts of sodium citrate, 10 to 20 parts of modified nano titanium dioxide, 7.2 to 11.2 parts of stearic acid, 0.4 to 1.6 parts of calcium stearate, 0.04 to 0.08 parts of antioxidant 168, 0.36 to 1.12 parts of maleic anhydride grafted polyethylene, and 3 to 11 parts of cellulose nanofibers are added into a blender and mixed thoroughly, and then extruded and granulated using a twin-screw extruder.

6. The method for preparing a self-cleaning single-layer foamed diffusion plate according to claim 5, characterized in that: The preparation of the modified nano titanium dioxide comprises the following steps: 7 to 9 parts of γ-aminopropyltriethoxysilane, 5 to 9 parts of polypyrrole, and 32 to 38 parts of nano titanium dioxide powder are dissolved in 38 to 52 parts of anhydrous ethanol and stirred for 20 to 40 minutes, and then 4 to 6 parts of nano silver are added in batches and intermittently ultrasonicated for 20 to 40 minutes. The ultrasonic power is 50 to 150 W, that is, the ultrasonication is stopped for 5 minutes for 5 minutes, and the precipitate is collected by centrifugation, and the precipitate is washed with anhydrous ethanol for 3 to 5 times. The washed precipitate is dried at 40 to 60° C. for 2 to 4 hours to obtain the modified nano titanium dioxide.

7. The method for preparing a self-cleaning single-layer foamed diffusion plate according to claim 6, characterized in that: In the process of preparing the composite foaming agent masterbatch, the speed of the mixer is 500-1000 r / min, the speed of the twin-screw is 40-60 r / min, and the extrusion temperature of the twin-screw is 130-150°C.

8. The method for preparing a self-cleaning single-layer foamed diffusion plate according to claim 6, characterized in that: During the preparation of the modified nano titanium dioxide, the speed of the stirrer is 500-1000 r / min.

9. The method for preparing a self-cleaning single-layer foamed diffuser plate according to claim 4, characterized in that: The temperature of the upper and lower electromagnetic heating rollers for hot pressing and ironing is 190-220°C.

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