Optical grade transparent plastic sheets have become indispensable core materials in modern optoelectronic manufacturing, architectural decoration, optical instrument production, and new energy industries. PC, PMMA, and GPPS transparent boards occupy dominant market shares in the high-precision transparent sheet field by virtue of their unique optical performance, mechanical properties, and processing adaptability. PC sheets feature high impact resistance and strong toughness, PMMA boards excel in ultra-high light transmittance and weather resistance, and GPPS sheets provide excellent surface flatness and low-cost optical molding performance. These three types of optical transparent materials cover low, medium, and high-end application scenarios of transparent plastic panels.
The production of optical grade PC, PMMA, and GPPS transparent boards puts forward extremely strict requirements on extrusion equipment, extrusion process precision, and molding stability. Unlike ordinary decorative plastic sheet extrusion, optical transparent sheet production requires zero surface scratches, no crystal points, uniform light transmittance, stable thickness tolerance, and low internal stress. Ordinary general-purpose plastic sheet extrusion lines are difficult to meet optical-grade production standards, prone to defects such as surface haze, material bubbles, thickness deviation, and light scattering, resulting in unqualified optical performance of finished products.
YUANSU, a professional manufacturer of high-precision plastic sheet extrusion equipment, independently develops and manufactures dedicated PC/PMMA/GPPS optical grade transparent board production lines, providing one-stop professional extrusion solutions for global optical transparent sheet manufacturers. Optimized targeting the optical performance requirements and physical characteristics of PC, PMMA, and GPPS materials, YUANSU optical sheet extrusion line abandons general-purpose equipment design defects, adopts precise melt plasticization, low-stress molding, dust-free extrusion, and high-precision calendering technology, and can stably produce high-transparency, high-flatness, low-defect optical-grade transparent sheets. This article comprehensively analyzes the equipment structure, process advantages, technical parameters, project cost, operation maintenance, and application scenarios of YUANSU optical grade transparent sheet extrusion production lines, providing systematic investment and technical guidance for optical sheet production project construction and equipment upgrading.
1. Industry Overview of Optical Grade PC/PMMA/GPPS Transparent Sheets
1.1 Core Performance Characteristics of Three Optical Transparent Materials
PC, PMMA, and GPPS are the three most widely used optical transparent plastic materials in the industry, each with unique performance advantages and targeted application scenarios, putting forward differentiated technical requirements for extrusion production lines. PC (Polycarbonate) optical sheets have a light transmittance of 89% to 91%, ultra-high impact resistance, tensile strength, and bending resistance, excellent low-temperature toughness, and can maintain stable performance in extreme temperature environments. They are mainly used for high-strength optical protection panels, display screen baffles, and new energy equipment transparent parts.
PMMA (Polymethyl Methacrylate), also known as acrylic, is a high-end optical transparent material with a maximum light transmittance of 92.5%, no visible light scattering, excellent weather resistance, anti-ultraviolet aging performance, and stable optical performance for long-term outdoor use. Its surface finish is higher than PC and GPPS materials, and it is the preferred material for high-precision optical lenses, light guide plates, architectural transparent curtain walls, and high-end display panels.
GPPS (General Purpose Polystyrene) optical sheets have ultra-high surface flatness, uniform internal molecular structure, no optical distortion, and low production cost. Although their impact resistance and weather resistance are slightly lower than PC and PMMA materials, their excellent optical uniformity makes them suitable for medium-end optical display panels, lighting lampshades, and ordinary optical decorative transparent parts, with extremely high market cost performance.
1.2 Optical-Grade Production Standards and Industry Pain Points
Optical-grade transparent sheet production has strict industry unified standards, requiring finished sheets to have no surface scratches, no bubbles, no crystal points, no impurity particles, and uniform thickness tolerance controlled within ±0.02mm. The light transmittance deviation of the whole sheet is less than 1%, and the internal stress is low to avoid light refraction distortion and post-production warping deformation. At the same time, the finished sheets need to pass professional optical testing to meet the matching requirements of optoelectronic equipment and precision optical instruments.
Most ordinary sheet extrusion lines on the market cannot meet optical-grade production requirements. Common production defects include unstable melt plasticization leading to crystal points and haze, low calendering precision causing uneven sheet thickness, poor dust-proof design leading to surface impurity particles, and unreasonable cooling process leading to excessive internal stress of sheets. These defects directly lead to unqualified optical performance of finished products, high defective rate, and low market competitiveness, which are the core pain points restricting the production and development of high-quality optical transparent sheets.
1.3 Market Demand and Development Trend of Optical Transparent Sheet Extrusion Lines
With the rapid development of optoelectronic display, intelligent equipment, new energy photovoltaics, and high-end architectural decoration industries, the global market demand for optical grade PC, PMMA, and GPPS transparent sheets continues to grow steadily. The market has higher and higher requirements for sheet optical precision, surface quality, and production efficiency, forcing sheet production enterprises to eliminate backward general-purpose extrusion equipment and upgrade to professional optical-grade dedicated extrusion lines.
High-precision, low-defect, multi-material compatible optical sheet extrusion production lines have become the mainstream development trend of the industry. Multi-functional equipment that can adapt to the switching production of PC, PMMA, and GPPS three materials has become the preferred choice for most medium and large-sized sheet manufacturers, which can effectively reduce equipment investment costs and improve production flexibility.
2. Structural Composition and Working Principle of YUANSU Optical Sheet Extrusion Line
2.1 Complete Line Core Equipment Configuration
YUANSU PC/PMMA/GPPS optical grade transparent board production line adopts customized integrated high-precision configuration, specially optimized for optical material extrusion characteristics. The complete production line consists of automatic quantitative feeding system, drying and dehumidification system, special optical screw extrusion host, high-precision hydraulic screen changer, static mixing system, optical-grade sheet mold, three-roll calendering shaping system, constant-temperature cooling conveying system, automatic thickness detection system, surface dust removal and protection system, fixed-length cutting machine, and finished product stacking system.
Each functional system is designed independently for optical production standards. The closed dust-free feeding and drying system avoids material contamination and moisture bubbles; the optimized screw structure ensures uniform melt plasticization without material degradation; the high-precision calendering and thickness control system realizes ultra-precise sheet molding; the surface protection system ensures zero defect of finished sheet surface, fully meeting the production requirements of optical-grade transparent sheets.
2.2 Working Principle of Optical-Grade Special Extrusion Host
The extrusion host is the core equipment that determines the melt quality of optical sheets. YUANSU adopts a specially optimized single-screw extrusion structure for optical transparent materials, with a customized screw length-diameter ratio and compression ratio suitable for PC, PMMA, and GPPS materials. Different from ordinary sheet extrusion screws, the optical-grade screw adopts low-shear uniform plasticization design, which can fully melt and homogenize materials under low shear force, avoiding material molecular chain fracture and degradation caused by excessive shear heat, preventing yellowing, haze and crystal points of transparent materials.
The equipment is equipped with a precise segmented temperature control system, which independently controls the temperature of each barrel section and the machine head mold, with temperature control accuracy up to ±0.5℃. Accurate temperature control ensures that PC, PMMA, and GPPS materials are melted in the optimal temperature range, eliminating unmelted particles and thermal decomposition impurities. The matched high-precision static mixer further homogenizes the melt flow and temperature, ensuring consistent optical performance of the extruded sheet in all regions.
2.3 High-Precision Calendering and Low-Stress Molding Principle
The three-roll calendering shaping system is the key to realizing ultra-flat and low-stress molding of optical sheets. YUANSU optical sheet production line adopts horizontal three-roll precise calendering structure, with all rolls made of high-precision mirror chrome-plated rollers, achieving ultra-high surface smoothness to ensure no scratch marks on the sheet surface. The three rollers adopt independent servo speed regulation and gap micro-adjustment technology, with gap adjustment accuracy up to 0.01mm, realizing precise control of sheet thickness.
The constant-temperature circulating water cooling system inside the calender rollers ensures uniform temperature of the roller surface, avoiding local temperature difference leading to uneven sheet cooling and internal stress concentration. The gradual cooling and low-speed molding process effectively releases the internal stress of the sheet, preventing optical distortion, warping and shrinkage deformation of the finished sheet in later use, and ensuring stable optical performance of the product.
2.4 Dust-Free Protection and Precision Detection System Principle
Optical transparent sheets are extremely sensitive to dust and tiny impurities, and micron-level particles will cause light scattering and affect optical performance. YUANSU production line is equipped with a full-process closed dust-free protection device from melt extrusion to finished product cutting, isolating external dust pollution. The online air dust removal system continuously cleans the sheet surface to ensure zero impurity adhesion on the sheet surface.
The real-time online thickness detection system continuously monitors the sheet thickness data, and the intelligent control system automatically calibrates the calender roller gap according to the detection data, realizing closed-loop automatic adjustment of thickness, ensuring that the thickness tolerance of the whole sheet is always within the optical-grade standard range, and greatly reducing the defective rate of products.
3. Core Technical Advantages of YUANSU Optical Board Production Line
3.1 Multi-Material Compatible Extrusion Technology
Most professional optical sheet extrusion equipment on the market can only produce a single type of transparent material, resulting in single production capacity and high equipment investment cost for enterprises. YUANSU independently optimizes the screw structure, temperature control parameters and mold runner design, realizing one equipment compatible with high-precision extrusion production of PC, PMMA, and GPPS three optical transparent materials. Users can switch production formulas through the intelligent control system according to production needs, realizing rapid switching of different material optical sheet production without replacing core equipment.
This multi-material compatible design greatly improves the production flexibility of the production line, enables enterprises to flexibly respond to market order changes, covers high, medium and low-end optical sheet product markets, and maximizes the utilization rate of equipment and plant resources.
3.2 Ultra-Low Defect Optical Molding Performance
Through low-shear uniform plasticization technology, full dust-free closed production design, and high-precision constant-temperature calendering process, YUANSU optical sheet production line completely eliminates common defects such as sheet bubbles, crystal points, haze, surface scratches, and optical distortion. The light transmittance of produced PMMA sheets can reach up to 92.5%, PC sheets up to 91%, and GPPS sheets up to 90%, all meeting international optical-grade industrial standards.
The finished sheet has uniform internal molecular structure, extremely low internal stress, no warping and deformation after long-term placement, stable optical performance, and can meet the strict application requirements of precision optical instruments, high-end display equipment and optoelectronic products. The product qualified rate is as high as 99.8%, far higher than the industry average level of ordinary equipment.
3.3 High Production Efficiency and Low Material Loss Rate
YUANSU optical grade extrusion line adopts high-efficiency melt conveying and intelligent automatic control technology, with stable and efficient continuous production capacity. Compared with traditional optical sheet extrusion equipment, the production efficiency is increased by 25% to 30%. The precise metering feeding system and low-loss extrusion process reduce the material waste rate to less than 1.2%, while the material waste rate of ordinary optical production lines is generally 4% to 6%.
The equipment supports 24-hour uninterrupted continuous production, with stable operation and low failure rate. The automatic thickness adjustment and defect detection function avoid mass defective product production, effectively improving production efficiency and product yield, and bringing significant cost-saving benefits to enterprise production.
3.4 Energy-Saving and Intelligent Operation Design
The production line adopts intelligent frequency conversion energy-saving drive technology and segmented precise heating control system, which can automatically adjust power output according to production load, avoiding invalid energy consumption. Compared with traditional optical extrusion equipment, the unit energy consumption is reduced by 20% to 25%, greatly saving long-term production energy costs for enterprises.
The full PLC intelligent control system integrates parameter storage, automatic debugging, fault self-detection and alarm functions. It can store exclusive production formulas for PC, PMMA, and GPPS materials, realizing one-click switching of production parameters, reducing manual debugging errors, and improving production automation and intelligence level.
4. Detailed Technical Parameters of Optical Grade Transparent Sheet Extrusion Line
4.1 Host Extrusion Core Parameters
YUANSU PC/PMMA/GPPS optical sheet special extrusion host is equipped with optical-grade special screw with diameter of 80mm to 110mm and length-diameter ratio of 33:1, which is the optimal parameter configuration for multi-material optical transparent sheet extrusion. The screw adopts low-shear uniform plasticization design, which is specially adapted to the thermal melting characteristics of PC, PMMA and GPPS materials, avoiding material thermal degradation.
The screw speed is adjustable from 0 to 60r/min with stepless speed regulation, realizing flexible adjustment of extrusion output. The segmented independent temperature control system has a temperature control accuracy of ±0.5℃, which can accurately match the melting temperature requirements of different optical materials. The stable melt pressure control system ensures that the melt pressure fluctuation is less than ±0.3MPa, providing stable power support for high-precision sheet molding.
The single-hour maximum output of the equipment ranges from 350kg to 550kg according to different materials and sheet thickness specifications, meeting the mass production demand of high-standard optical transparent sheets.
4.2 Sheet Molding and Calendering Parameter Specifications
The production line supports the production of optical sheets with thickness specifications from 0.5mm to 10mm and width from 1200mm to 2000mm, covering all mainstream specifications of industrial optical transparent sheets. The three-roll mirror calendering system has a roller surface flatness error less than 0.005mm, and the sheet thickness tolerance after calendering is stably controlled within ±0.02mm, reaching the international optical-grade precision standard.
The calender roller adopts constant-temperature circulating cooling design, with roller surface temperature fluctuation less than ±1℃, ensuring uniform cooling and low-stress molding of sheets. The sheet traction speed is adjustable from 1m/min to 15m/min, realizing matching speed regulation for different thickness and width specifications to ensure stable sheet molding quality.
4.3 Complete Line Supporting Functional Parameters
The automatic dehumidification and drying system has a drying temperature adjustable from 60℃ to 120℃, which can completely remove material moisture, effectively eliminating sheet bubble defects caused by moisture. The hydraulic automatic screen changer realizes non-stop screen changing, avoiding production interruption and improving production continuity.
The online thickness detection and closed-loop adjustment system realizes real-time monitoring and automatic correction of sheet thickness. The fixed-length cutting precision error is less than ±1mm, and the cutting section is flat and burr-free, which does not affect the subsequent deep processing and application of optical sheets.
5. Equipment Price and Comprehensive Project Cost Analysis
5.1 2026 Complete Line FOB Price Estimation
The FOB price of YUANSU standard PC/PMMA/GPPS optical grade transparent board complete extrusion production line is 65,000 to 82,000 US dollars. The conventional standard model suitable for 1200mm to 1600mm width sheet production is priced at 65,000 to 73,000 US dollars. The wide-width high-precision model supporting 1600mm to 2000mm ultra-wide optical sheet production, equipped with full intelligent detection and automatic adjustment system, is priced at 73,000 to 82,000 US dollars.
The single extrusion host price ranges from 32,000 to 38,000 US dollars according to different specifications. Users can choose standard configuration or customized configuration according to their own production scale and product precision requirements, realizing flexible investment matching.
5.2 Investment Cost Comparison with Single-Material Optical Extrusion Lines
The one-time investment cost of YUANSU multi-material compatible optical sheet extrusion line is about 12% lower than the total investment of purchasing three sets of single-material dedicated production lines. For enterprises that need to produce PC, PMMA, and GPPS optical sheets at the same time, adopting YUANSU multi-functional integrated equipment can save a lot of equipment procurement costs, plant space costs, and manual operation costs.
Compared with ordinary single-material optical extrusion lines on the market, YUANSU equipment has higher production precision and lower defective rate. Although the unit price is slightly higher than ordinary low-precision equipment, the annual comprehensive cost saving of material waste and defective product loss can reach 18,000 to 25,000 US dollars, and the investment cost difference can be fully recovered within 1 to 2 years of stable production, with obvious long-term cost performance advantages.
5.3 Daily Operation and Annual Maintenance Cost Budget
YUANSU optical sheet extrusion line adopts energy-saving and low-wear design, with low daily operating cost. The daily power consumption cost of a complete production line is 50 to 65 US dollars, and the daily water circulation and gas consumption cost is 8 to 12 US dollars. The daily consumable costs such as filter screen replacement and dust-free cleaning accessories are 7 to 10 US dollars, and the daily comprehensive operating cost is controlled within 90 US dollars.
In terms of equipment maintenance, the core screw, barrel and calender roller adopt high-strength wear-resistant and anti-corrosion materials, with a service life of more than 10 years. The daily maintenance is simple and convenient, with a monthly routine maintenance cost of 50 to 70 US dollars and an annual comprehensive maintenance cost of less than 700 US dollars. The equipment failure rate is lower than 0.2%, which greatly reduces the production shutdown loss caused by equipment failure.
5.4 Project Investment Return Benefit Analysis
Optical grade PC, PMMA, and GPPS transparent sheets have high market added value and stable market demand. A single YUANSU complete extrusion line can produce more than 7 tons of high-quality optical sheets per day. After deducting raw material cost, operating cost and equipment depreciation cost, the daily net profit of the production line can reach 900 to 1300 US dollars. The equipment investment payback period is about 16 to 20 months, with stable and reliable project benefits and low investment risk.
6. Main Application Scenarios of Optical Grade PC/PMMA/GPPS Transparent Sheets
6.1 Optoelectronic Display and Lighting Industry
High-precision PMMA and GPPS optical sheets produced by YUANSU production line are widely used in LED light guide plates, display screen protective panels, advertising light box panels, and indoor and outdoor lighting lampshades. The ultra-high light transmittance and uniform light conduction performance ensure no light spot and dark area in lighting and display products, improving product display effect and lighting quality.
6.2 Architectural Decoration and Transparent Decoration Engineering
Weather-resistant PMMA optical sheets and high-toughness PC sheets are suitable for architectural transparent curtain walls, indoor decorative transparent partitions, sightseeing corridor protective plates, and outdoor decorative transparent panels. The products have excellent weather resistance and impact resistance, can resist long-term sun exposure and wind and rain erosion, and maintain stable transparency and appearance for a long time, reducing later maintenance costs.
6.3 Precision Optical Instrument Manufacturing
Low-stress and high-uniformity optical transparent sheets meet the production requirements of precision optical lenses, instrument transparent windows, optical detection baffles and other components. The products have no optical distortion and high dimensional stability, which can ensure the detection accuracy and use stability of precision optical instruments.
6.4 New Energy and Intelligent Equipment Industry
High-toughness PC optical sheets are widely used in new energy photovoltaic panel protective covers, intelligent equipment display protective plates, and electrical equipment transparent insulating parts. The products have both optical transparency and mechanical strength, with good insulation and impact resistance, meeting the safety and performance requirements of new energy and intelligent equipment.
7. Standard Production Process and Material Switching Operation Specifications
7.1 Pre-Production Debugging and Dust-Free Preparation
Before the production of optical transparent sheets, the production line needs to complete closed dust-free cleaning to ensure no dust and impurities in the extrusion and molding area. Turn on the material dehumidification and drying system, dry PC, PMMA, or GPPS raw materials according to the material moisture standard to eliminate internal moisture bubbles. Turn on the segmented heating system, set the optimal temperature parameters according to different material characteristics, and keep warm for 60 minutes after reaching the preset temperature to ensure uniform temperature of each equipment component.
Debug the screw speed, feeding volume, calender roller gap, and traction speed parameters, conduct trial extrusion production, detect sheet thickness, light transmittance, surface flatness and other optical indicators, fine-tune the process parameters according to the test results, and lock the optimal production formula after the product meets the optical-grade standard.
7.2 Differentiated Process Parameters for Three Optical Materials
For PMMA optical sheet production, the extrusion temperature is controlled at 180℃ to 210℃, with low shear speed to avoid material yellowing. The calendering temperature is kept stable at 80℃ to 90℃ to ensure ultra-high surface finish and light transmittance. For PC sheet production, the extrusion temperature is controlled at 220℃ to 250℃, with enhanced dehumidification treatment to eliminate bubble defects, and low-stress cooling process is adopted to maintain sheet toughness.
For GPPS optical sheet production, the extrusion temperature is controlled at 190℃ to 220℃, and the calendering gap is precisely calibrated to ensure ultra-flat sheet surface. The intelligent system stores the exclusive parameter formulas of the three materials, realizing one-click switching during production replacement, avoiding repeated debugging and improving production efficiency.
7.3 Post-Production Shutdown and Equipment Maintenance Process
After daily production is completed, stop the feeding system first, keep the screw running for 15 to 20 minutes to completely discharge the residual melt in the barrel and mold, preventing material carbonization and adhesion from affecting subsequent optical production quality. Gradually reduce the equipment temperature, and cut off the power after the temperature drops to the safe range.
Thoroughly clean the mold runner, filter screen, calender roller surface and dust-free protection system to ensure no residual materials and dust impurities. Complete daily equipment lubrication and parameter resetting to ensure that the equipment is in optimal standby state for the next production.
8. Daily Maintenance, Fault Prevention and Solution Measures
8.1 Daily Routine Inspection and Maintenance Work
Before daily startup, inspect the operation status of the dust-free system, dehumidification system and temperature control system to ensure stable operation of each functional module. Check the flatness and cleanliness of the calender roller surface, the tightness of the transmission system, and the sensitivity of the thickness detection sensor to avoid equipment abnormalities affecting optical sheet quality.
During production, monitor sheet surface quality, optical performance and thickness data in real time, and adjust process parameters in time if slight defects are found. After shutdown, complete full equipment cleaning and dust removal, replace aging filter accessories, and supplement transmission lubricating oil to maintain long-term stable equipment performance.
8.2 Regular Periodic Comprehensive Maintenance Specifications
Carry out comprehensive maintenance every month, including screw surface wear detection, mold precision calibration, calender roller flatness detection, and temperature and pressure parameter calibration. Clean the internal pipeline of the dust-free system and dehumidification system to ensure stable dust removal and drying effect.
Carry out a comprehensive equipment overhaul every six months, detect the aging degree of electrical components and wearing parts, replace aging parts in advance, calibrate the automatic thickness adjustment accuracy and cutting precision, eliminate potential faults, and ensure that the equipment always meets optical-grade production precision standards.
8.3 Common Optical Sheet Production Defects and Solutions
Common defects in optical sheet production include surface haze, tiny bubbles, thickness deviation, and surface impurity particles. Sheet haze is mainly caused by incomplete material plasticization or excessive shear heat, which can be solved by optimizing temperature parameters and reducing screw shear speed. Tiny bubbles are caused by insufficient material drying, which can be eliminated by extending dehumidification and drying time.
Thickness deviation is solved by calibrating calender roller gap and updating thickness detection parameters. Surface impurity particles are caused by poor dust-free effect, which can be solved by cleaning the dust-free system and replacing filter accessories. YUANSU equipment’s intelligent fault prompt system can quickly locate defect causes, greatly improving maintenance efficiency and reducing defective product loss.
9. YUANSU Brand Advantages in Optical Sheet Extrusion Equipment
9.1 Professional Optical Extrusion Technology Accumulation
YUANSU has long been committed to the research and development and production of high-precision plastic sheet extrusion equipment, with rich technical accumulation in optical-grade transparent sheet extrusion technology. The company’s professional technical team continuously optimizes low-stress molding, dust-free production and multi-material compatible extrusion technology, and has formed mature and stable optical sheet production line solutions, which can accurately meet the high-precision production needs of PC, PMMA, GPPS and other optical materials.
9.2 High Precision and High Cost Performance Equipment
Compared with imported high-end optical extrusion equipment, YUANSU optical sheet production line has the same ultra-high production precision and stable performance, while the equipment procurement cost is 30% lower than imported equipment. With low failure rate, low energy consumption and low material loss rate, the equipment has extremely high long-term cost performance, which is very suitable for medium and large-scale optical sheet production enterprises to upgrade equipment and expand production.
9.3 Full-Cycle Technical Support and After-Sales Service
YUANSU provides one-stop full-process services including equipment installation, on-site commissioning, optical production technology training, and long-term after-sales maintenance. Professional technical engineers guide customers to master equipment operation, material switching debugging and daily maintenance skills, helping customers quickly realize stable mass production of optical-grade sheets. Long-term spare parts supply and remote technical support ensure the sustainable and stable operation of customer production lines.
10. Conclusion
Optical grade PC, PMMA, and GPPS transparent sheets are core basic materials in optoelectronic, new energy, architectural decoration and other industries, and professional high-precision extrusion production lines are the key to ensuring product optical performance and production quality. YUANSU multi-material compatible optical transparent board production line solves many industry pain points of traditional single-material equipment and ordinary low-precision equipment, such as single production capacity, high defect rate, large material loss and high energy consumption through optimized optical-grade special structure design, dust-free low-stress molding technology and intelligent precise control system.
With the advantages of multi-material compatibility, ultra-high molding precision, low defective rate, high production efficiency and low comprehensive operating cost, YUANSU PC/PMMA/GPPS optical grade transparent sheet extrusion solutions can help sheet production enterprises produce high-standard optical transparent sheets that meet industrial application requirements, effectively reduce project comprehensive production costs, improve product market competitiveness, and obtain stable and high economic benefits. With the continuous expansion of the global optical material market, high-precision and multi-functional optical sheet extrusion production lines will become the core equipment for the high-quality development of the transparent plastic sheet manufacturing industry.
