Document zBonr10bw9VQ62j0mNXeJGJ7

UNION CARBIDE NEW PRODUCT DATA UNION CARBIDE CORPORATION PLASTICS DIVISION 270 PARK AVENUE, NEW YORK, N. Y. 10017 BAKELITE Rigid Vinyl Powder Blend for Pipe INTRODUCTION i ncrCiv/rn JUL 2 2 1966 R. N Wheeler product designation QGPB-9311 Gray 5775 White 5135 ISSUE NUMBER 1 DATE July 1, 1966 BAKELITE rigid vinyl compound QGPB-9311 is a powder blend designed for rigid pipe applications. QGPB-9311 is a normal impact product whose versatile properties meet both PVC 1120 (Type I, Grade 1) and PVC 1120 (Type I, Grade 2) requirements of the Plastics Pipe Institute of the S.P.I. This compound is approved by National Sanitation Foundation for use in potable water systems and also qualifies under Commercial Standards CS-256-63 (Pressure Pipe) and CS-272-65 (Drain Waste & Vent Pipe) QGPB-9311 is available as an easy handling, free flowing powder that offers better consistency, greater latitude in the use of regrind, and at the same time, permits higher output rates than pellet compounds. The excellent properties of this rigid vinyl powder suggests its use for water, gas, chemical and petroleum piping systems. Other areas of application include irrigation and sprinkler systems. PROPERTIES Powder Blend The physical properties of QGPB-9311 are listed in Table I which compares the properties of this material with the minimum require ments of ASTM Specification D1784-60T for Type I Grade 1 rigid PVC and a competitive rigid vinyl compound. QGPB-9311 offer advantages in both strength and heat distortion characteristics. Table I Property ASTM Method Type I Grade 1 QGPB-9311 Competitive Product Specific Gravity Tensile Strength, psi Tensile Modulus, psi D1505 D638 D628 _ 7000 400,000 - Continued - 1.386 8200 418,000 1.390 7900 396,000 "BAKELITE", "KRENE", "VINYLITE" and UNION CARBIDE are registered trade marks of Union Carbide Corporation. This information is offered solely for your consideration, investigation and verification and is not to be construed as a warranty or representation for which we assume legal responsibility. In using these materials, you must establish for yourself the most suitable formulations, production methods, and control tests to ensure the uniformity and quality of your product. Nothing contained herein is to be understood as permission or recommendation to practice a patented invention without a license, and you should determine whether relevant patents exist. Union Carbide has highly trained engineers in the field ready to serve you, and these technical representatives will be glad to dis cuss individual problems. 6-1178 &A-32&-18B 'TrQ `7* 1 2 Table I (Cont'd.) Property Heat Distortion Temp. @ 264 psi C. Izod Impact Strength ft.lbs./in. notch Flexural Strength, psi Flammability Chemical Resistance, Sulfuric Acid 93% 14 days floatation at 55C. Change in Weight max.% Change in Flexural StT. max.7. ASTM Oil #3 30 days immersion (? 23C. Change in Weight max.% ASTM METHOD D648 D256 D790 D543 D471 Type I Grade 1 70 0.65 11,000 SE QGPB-9311 75 1.5 14,530 SE +5.0/-0.1 +5.0/-25.0 +0.104 +1.17 +1.0/-1.0 +0.0345 Competitive Product 72 1.5 14,049 SE +3.4 -3.44 +0.0240 Pi^e Instantaneous burst strength of 1" (SDR 13.5) pipe produced from QGPB-9311 is 1450 psi (9100 psi Iso hoop stress). The performance of QGPB-9311 pipe under sustained pressure is excellent. As indicated in Figure 1, the hoop stress is 5200 psi at 2000 hours of testing. Extrapolation of this data by computer indicates the ability of the pipe to withstand 4200 psi (670 psi in 1" SDR 13.5 pipe) for 11-1/2 years (100,000 hours), well above the PPI requirements of 3840 psi for Type 1120 pipe. Powder vs Pellets Production of rigid PVC pipe from powder blend has gained widespread acceptance over pellet extrusion in recent years for several reasons. Because of the limited heat history powder blends have received, they possess much greater residual heat stability than hot processed pellets. The better stability permits 30-40F. higher stock temperature, resulting in substantially higher production rates and better physical properties. The better stability of the powder permits greater regrind percentages without impairing pipe properties. The higher extruding temperature and the inherently more uniform quality of powder blend give greater assurance of producing pipe of superior quality^ providing years of dependable service. 3 EQUIPMENT Since the extruder must be depended upon not only to melt the compound as with pellets, but to compact and fuse it before forming the pipe, somewhat different equipment is required to assure successful production from powder. Extruder QGPB-9311 can be extruded easily on 2-1/2", 3-1/2" and 4-1/2" machines designed for rigid PVC powder blend materials. To compact the powder from a bulk density of 35 lbs./ft.^ to a melt density of 88 lbs./ft.3 air must be removed while compacting and fluxing it. This may be accomplished through the use of either a typical vented extruder or a vacuum hopper. QGPB-9311 has been extruded successfully in both ways. A low shear auger type vertical screw (stuffer) in the hopper is desirable to assure uniform flow of powder to the extruder screw regardless of free flowing qualities of the powder. In addition, the use of the stuffer will increase significantly the output rate; about 30-50 lb./hr. in a 2-1/2" extruder. The extruder barrel should have provisions for cooling in order to control a rise in stock temperature as screw speed is increased to increase production. Screw Because the screw has the greatest influence on the performance of an extruder, careful attention must be given to its design to assure maximum mixing at screw speeds which optimize output rate while limiting stock temperature to 400-410P. Any screw handling powder blend should be hard chrome plated to increase its life. A two-stage screw having a length to diameter ratio of 24 to 1 and constant pitch equal to the diameter is recommended. The compression ratio in the first stage where fluxing, compacting and fusing occurs should be 3.0 -3.5/1. Since a fluxed homogeneous stock is delivered to the second stage, less compression is required; approximately 2/1. The flight depth at the end of the first stage and at the discharge section have an important influence on the shear developed and, therefore, will influence the output rate at given screw speeds as well as the rate of stock temperature rise as the screw speed is increased. The screw should be cored for cooling, preferably with circulating oil, so that the stock temperature can be controlled to achieve optimum performance at various speeds. A screw design offering flexibility for rigid PVC compositions in a 2-1/2" extruder and well suited for QGPB-9311 will have the dimensions shown in Figure 2. The sections are labelled with the number of flights in uce 039373 4 that section shown. The flight depth in the fed, decompression and two metering sections are also indicated. Dies Dies should be carefully streamlined to eliminate any potential stagnation areas which could result in material decomposition. All interior surfaces of the die should be polished and chrome plated. Land lengths should be in the range of 10-15 times the average wall thickness of the pipe to assure good welding of the stock past the spiders supporting the pin and to develop gloss. It will be noted the inherently high gloss of QGPB-9311 makes it unnecessary to induce surface gloss by special die and pin temperatures. No attempt will be made to recommend pin and die sizes since head pressure, stock temperature, output rate, will all influence the swelling that occurs as the stock leaves the extruder and the subsequent shrinkage as the pipe is cooled to room temperature. Sizing Because higher stock temperatures are required for good quality pipe from powder blend compared to pellets, handling the less viscous melt is more difficult and may require different sizing arrangements than those used for same size pipe made from pellets. Sizing with a vacuum has been found to.be ideally suited for rigid pipe extruded from QGPB-9311. The vacuum could be applied to a box containing several sizing plates or directly to a water cooled sleeve of about 2" length. Using negative pressure in this way to size the outside diameter of the pipe not only results in saving pipe quickly after start up but avoids the need of maintaining a seal and uniform air pressure on the inside of the pipe. Sizing the inside diameter with a water cooled mandrel can be very difficult. The taper of the mandrel must be exactly right to maintain good contact for rapidly cooling the shrinking pipe without the pipe sizing or dragging excessive ly on the mandrel. The amount of dimensional change occurring in the pipe over the length of the mandrel is dependent upon stock temperature and ex trusion rate which tends to make the taper requirements more critical. EXTRUSION A 2-1/2" Davis Standard extruder with a vacuum hopper and hopper stuffer were used to develop QGPB-9311 at Union Carbide Plastics' Application Development Center at Bound Brook, New Jersey. The conditions outlined in Table II resulted in an excellent balance between quality and production rate. ! !f.n 5 Table II Temperature Barrel Zones 1 Feed section 2 Transition 3 Metering 4 Decompression 5 Metering Die Zones 1 Adapter 2 Transition 3 Die lands Screen Head Pressure Screw Speed Temperature Stock Temperature Rate Sizing Die Pin Vacuum Sizing Box Sleeve diameter Distance from die Water Bath Pipe OD wall thickness 340F. 360 370 370 370 350 350 370 1-40 mesh 3000-4000 psi 65 rpm 180 - 210F. 390 - 410F. 180 lbs./hr. 1.420" 1.226" 1.314" 1.5" 40F. 1.320" 0.097" ISO HOOP STRESS, PSI FIGURE 1 TIME IN HOURS METERING DISCHARGE ~r~ 0.180" 4 VENT DECOMP RESSION METERING D __________Lt _ TRANSITION HOPPER STUFFER b \i FEEDING \ _______T_______ T 0.300" 0.130" v 0.400" 10"- 2 y2" 10" 7y2" 60" 15" 15" SECOND STAGE --4*-------------------- FIRST STAGE FIGURE 2