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PVC FABRICATION AND APPLICATIONS by W. C. DOUGLAS J. M. GYENGE GEORGE HACK IM A. J. HANLEY W , ' . I'i'111 j 1 . i. 1 . , > i ' i ; 1 ` 11 'i ; I!: < I u i v > r i [ L 11 i11 a i i !i a B,u ii M . : i, 'i l i r:. - iPi'i p .i ii v .] uppli' iii'U,-, in Mi < "i i i a ] I1 n g i :i c c i i n a Hr i n \ l i a 1 1 v ) , i r d ~`i i [ !ii' a 11 r k i i-in in i-il j i o a n >1 the li-1 r 1 D|iiiii-n t and ,,i in iiinlji) p l al i i /. r i ; dor v i n\ 1 resins. nince Ui i ,im t rrhn i r a [ 1 do 5 tic has been employed by The General Tire A Rubber (.umpariy as ferhuical Service Uieriist in the 1 1 c 1 d of polyurethane foams. He l = a member ot the Society o 1 P l a i r i c s ting l n e ers, J. M. Gyenge was graduated from Baldwin Wallace College in 1943 with a Bachelor of Science degree in Chemistry. He has done graduate work at Akron University in polymer chemistry. From 194b to 195b, he was a development chemist at the Akron Gov, rument Development Laboratories of Rubber Reserve. In The General Tire & Rubber Company's Chemical Division he has served as both Technical Service Representative and as Sales Development Engineer. He was appointed to his present position, Manager, Technical Service, in 1959, Mr. Gyenge is a member of the American Chemical Society. George Hackim was graduated from the University of Akron in 1947 with the degree of Bachelor of Science in Chemistry. First employed by the Sun Rubber Company, he came to The General Tire & Rubber Company in 1948 m the production training program. From a first assignment in Research, he was transferred to the Chemical Division in 1950 as Manager of Technical Service and later became Sales Manager. In the newly formed^ ChemicaL Plastics Division he was: Assistant Director of Sales, 1962; General Sales Manager, 1963; and has been Vice PresidentIndustrial Sales since early 1964. Mr. Hackim is a member of the American Chem ical Society, the Society of the Plastics Industry, and is former chairman of the Akron Rubber Group. Albert J. Hanley is Section Head of Plastic Evaluation and Application for The General Tire & Rubber Company. Graduated in 1920 from Massachusetts Institute of Technology with a Bachelor of Science degree in Chemical F.ngineering, he went on to serve as head of the chemistry department at Mount Saint Mary's College, Maryland, until 1926. He became, in turn, chief chemist at Textileather and Technical Director for Respro, Inc., plastics manufacturers, until these firms were absorbed by the parent company in 1955. At that time he became Group Head of Plastic Evaluation and Application until appointed to his present post in 1962. Mr. Hanley is a member of the American Chemical Society, the Society of Plastics Engineers, and the Society of Plastics Indus tries. .501 . \r II'- Lilt! l - - \pp 1 1 (' .1 l L U II 3 P\( , R, i ii Types Lonvei sion of He sin to Product A. Compoundi ng 1. Stabi lization 2 _ Plasticization 3. Lubrication 4. Pigmen t ation B. Processes and Fabrication 1. Dryb lending 2 . Banburying .3. Milling 4. Calendering 5. ExtFusion a. Rigid Vinyl b. Vinyl Foam 6. Blow Molding 71 . Compression Molding 8 . I n j ec tion Molding 9. Fluidized Bed Coatings 10. Contour Forming n. Assembly of PVC^Product c. De corative Effects 1. Embo s sing 2. Printing D. Mining and Processing of Plastisol Resi n s 1. Dip Co a c1ng 2. Slush Molding 3. Rotational Molding 4. PVC Foams oc'-I \1 i \ ! iiAi p! -V1 i i ii u ! a 'Tbiun u t p,,pt Pit into Ul ilicsr r i to-1! how p o 1 s v r n , 1 i I; I o I' l .1 o i , o b L a l n e ,i as II .lb b t. .1 t <: , PVC It a - v i- r \ 1 uni t ed use and the c o u commercial proi no to he pen ilo upon '>s mo d l t l c d t, l o n through eom poumlin g. The man y <: ompo bilious obtainable 1rom PVC. are highly a d ap t a b 1 e to a number o f o pei at l o n .b wh l c h e o n v oft. the maten q 1 s in f. o u s a b 1 e product s. Most PVC prod uc t s are obtained by calendering,. extrusion, and coating techniques. Other conversi on methods such as blow molding, c u rn p r ess i on rno 1 d i ng, injec11 on molding, and f1uldi zed bed are us ed to a 1 e s s e r degree. The mo 1 e c u1 a r weight of the resin, compounding, processing, and finishing all contribute ' The great van ft, C r t o rm an c e and appearance of the final product. --;iJ Jaes lor PVC make it one of Am erica' s most thriving and expanding industri e s . PVC, more than any other polymer, i s synonomous w i t h vers a till ty. II. End Use Applic a t i o n s In 1962, PVC b ocame the world's first billion pound plastic. Figure 1 allows the sales volumes of the various classifications of vinyl for 1962 and 1963. It can be seen from the curves that calendering and extrusion captures the bulk of the market. Poundage for 1963 was greater than in 1962 in every classification except miscellaneous, and the total increase for the one year period is 18%. Indications are that 1964 will show a similar increase over 1963 and PVC. seems headed toward a two billion pound market in the near future. As PVC has grown in volume, the price has dropped accordingly, further accelerating the plastics industry's interest in the material. The current low price of lbtf/'lh. contributes toward making PVC one of the first materi als considered when production of a new plastic article is being planned. Though the 1.40 specific gravity of the unp1 asticized resin is relatively liLgh, the pound-volume costs of the plasticized compounds are much more favorable. This poundage is nor. consumed as a single product or application, PVC has widespread utility in products ranging in stiffness from rigid sheet, for construction applications to flexible film for food wrapping. This extreme difference in end product application is possible because the basic vinyl polymer can be solvated by plasticizers over a range of concentrations. All of these PVC compounds are thermoplastic in character and acquire at som critical elevated temperature a rubber -like 'onsist. encyi Th e r e f o r e , it is not surprising that in the early days plasticized vinyl compounds were converted or formed t,o shape on equipment found in the rubber industry. Experience soon demonstrated that calendering, tubing, extruding, and pressing machines for rubber were inefficient for making quality vinyl products. "These same types of converting machines were modified in basic engineering design, temperature tange, and automatic control in order to manufacture vinyl end-products to extremely close dimensionnl tolerances. -1-  o SUBTOTAL USAGE OF PTC RESIiN (000,000 OF LBS.) t-Z> L-- c O CH o O '' G ~i 1962 J H O O IJ M S 1 H ' )Ad JO NOLUIWOSWOO ATHV3A ' I 1963 YEAH 1964 (E S T .) GRAND TOTAL IN H] LL] 0\ i fi> \ ; l 1 1 .1 r 1 L i ! , the h i lie p < > L \ v l !1 \ i h ! o l 1 ! e .hi t -* pc i '. me ! i . r ; wpo i 1 Z e li h\ all a pen - 1 O f. , riMi 1 noil, *) r i >) 1 ii L i mi l r i i. -i l i[*i <`s. h l ) j. \ ' \> ii ['[him .-i j t i h i -> p ap c r , t he e mp L a s i i wi 1! he placed on the s u ' p e n si./ : lit I .* -> 1 n , PY(. poivniei can hr made i n a wide lunge o 1 c h am 1 e u g t h s or mo 1 e c u 1 a r weights. Fur control and i d e n Li fication purposes, t. h e m o 1 e c u 1 a r we i h L is characicrized by the polymer's int n nsie vincosi ty in a solvent solution The higher molecular wei ght polymers p o asesi higher tens) 1 e strength and hardness, better s'si seance to flow at. elevated temperatures, and Utpr o v e d solvent resistance, when compared to their lower mo 1 ecu 1ar weight homo logs. Table 1 Effect of Moleculai Weight on PVC Properties Resin Vygeu 85 Vygen 105 Vygen 110 Vygen 120 Molecular Weight* Intrinsic Viscosity 74,000 . 80 83,000 .93 Tensile Strength, psi** Ultimate Elongation, %** Tensile Stress at 100% Elongation, psi** Shore A Hardness, 0 Sec . 10 Sec. 2160 230 1290 91 80 2490 300 1400 91 80 Formulation Resin - 100 pares DOP - 50 parts Ba-Cd Stabi 1izer - 2 parts 93,000 1.03 2730 340 1420 91 81 107, 000 1.18 2890 350 1 46 0 92 82 * D. J. Mead and R. M. Kuo ss, J. American Chemical Society , 64, 277, ( 1 9 42 ** ASTM D-412-61T In a typical formulation using 50 parts of dioctyl phthalat.e (DOP) plas ticizer per hundred parts of resin and resins of differing intrinsic viacn.iitv ranging from 0.80 to 1.18, it can be seen that the tensile strength, elon gation at break, and Shore A hardness increase with increasing molecular weight. Figures 2 and 3 show these points graphically. .3 Ml ^ , -t bENC G0G4`"j 1 III >-,111 t 11 i i id11 ; > i g ii r > 1-. ; \ > i ; , , , 1 ;i , i , I LKMt.T OK MOI.Kt l I, \H ViMOlll' ON 0\1 KNOKll 1 NO IKMl-'Lll A II HI- Higher processing temperatures tend in create resin instability problems it the processing cycle is of long duration. A compromise must often be made between the molecular weight resin selected and the processing tech nique, Ihe higher molecular weight resins are used in extrusions of flexible tubing, welting, electrical components, garden hose, and calendered film which require short dwell times at rhe elevated processing temperatures. Intermediate molecular weight resins are used in film and sheet, coated fabrics and rigid applications. Low molecular weight resins are used in f 1 u i d i zed bed coatings, phonograph records and injection molded parts. 5 P[ odui ! I ) U [ 111 1 11 g S t a b 1 1 1 ' .i l i i) n V e v y t <_* w po 1 yme r s l nil r r tmlly po a sess outstanding heal or 1; l ^ h t i' e >i i .-j L a n t' e on long t eim e \ p o s ii i e , and polyvinyl chloride i, S I) o except\on . Th e :ien ce of PVC d egradation is well establl. sh ed and although complicated, is known to involve the loss of a chlorine and a hydrogen atom from adjacent carbon atoms on the backbone chain. .Strong alkali promotes this loss of hydrogen chloride. A slightly alkaline metallic salt will act as an acid acceptor and prevent further generation of HC1 along the polymer chain. Lead salts such as basic lead carbonate or lead silicate were the earli est stabilizers used in polyvinyl chloride. Lead stabilizers are still used in electrical insulation where the service specifications require up to a 105C temperature rating. Organo-lin compounds such as dibutyl tin dilaurate or tin maleate are liquid at processing temperatures and can be dispersed through the PVC compound more readily than solid metallic salts. They also protect the polymer by saturating the double bond created wherever HC1 is lost in the first, stage of decomposition. A major advance in stabilization was the discovery that organoeadmium compounds are synergized in their stabilizing action by companion barium organic compounds. These systems are readily dispersed and have limited solubility in plasticized PVC compounds and make possible haze-free products of good clarity and color. Plasticization It was stated previously that polyvinyl chionde resins are capable of being compounded into a wide variety of products having different degrees of flexibility and hardness. This great versatility is possible because of the softening action of plasticizers on the hard horny resin. In general, the degree of softness of the com pound will be in direct proportion to the plasticizer-resin ratio. By varying this ratio, a wide range of PVC properties can be achieved. The chemical function of a plasticizer is dependent upon the presence of polar groups in its molecular structure. This polarity allows the plasticizer molecules to be inserted between PVC resin molecules, neutralizing the Van der Waal or secondary valence bonds. This weakening of the Van der Waal forces creates localized flexible areas intermingled with resin strength areas. The combination re sults in a strong, yet pliable, polymer. The re is evidence that the plasticizer swells the amorphous regions and that the small regions of crystallites are unattacked or u n affected by the plasticizer. This situation is unique to polyvinyl -6- 0 0 0 4? 1 Mm,, !m` 1 It i' ' 1 ' 1 1 ' ' wiMk, >1 : < I r - 1 tMm - 1 L k t Mom M i b - 1 ) o 1 1 d \) i db 1 Dll ! f .t i ' Ldll `; " I 1 1` ' 1 ; 1 "; -- ` - * _ i, , i i . , , 1 ' ii ; * , ; ` '1 . " ,s , tail l mnnie i c L U 1 jj l (nl IJ F t, 3 o f s alls f tu t ij r y il u i i b i 1 i tv inquire t ii a t the sol V rn L or pi a s t. i c i /- L [L K agent have lung t <_ r m p er mane n t e . The p 1 a s t i i.' l /.Ff s h o u 1 d b l* a t lea =, r. a 'i p e rnuiruMi t a t he properly it a b l 1 Jl zed resin. To b e pe r mi ci[itiH , the p 1 a 'i t i ctzer must either b e a tnic solvent oi be U S S O (' { d [ed with a true ao 1 vc* tit tor the PVC resin. Th e plasticizer m u s L resist o x i d al ioh both during processing and du f ing long term i n - u s c a gin g tor periods up to five or more years. Its affinity to the l us ill must tie greater than to foreign substances which would normally contact the PVC product in service. For upholstery, these substances would include lesistance to wieking into clothing, dust or dirt, and soapy water washing. It must have a very low volatility to eliminate evaporation. It should be odorless and colorless in order to have widespread utility. When the material in question meets these specifications to a practical degree, it becomes known as a primary PVC plasticiser. Ordinarily, a plasticizer will be a high molecular weight ester formed by the reaction of an aliphatic alcohol of eight to twelve carbon chain length with an acid which may be either phthalic, azelaic, adipic, or sebaeic. Polymeric forms of esters are usually in the 2000-5000 molecular weight range. These plasticizers are used where special permanence is lequired. PUst icize r s are commonly liquids with viscosities which may be as low as a light oil or as thick as honey. They vary widely in their efficiency in f1exibl1izing the PVC resin and the particular proper ties contributed to the PVC product. For this reason, it is common practice to blend a mixture of plasticizers to obtain a compromise ol their individual assets and detects. It is this type of blending that makes vinyl products so versatile. figures 5, 6, and 7 show the effect of OOP plasticizer Idi-octyl phlhalale) concentration on the tensile strength, elongation and Sh orp A Hardness o t' a V y g f* n I '2 0 f o r m u [ a L i o w . Wti e r f1 except! on a l pormauernv m 11 i hip n ^ i o n a L stability i ^ demanded, c h Pin i c a L 1 y bound copolymers rind physical polymer blends provide the answer. Nitrile rubber (buLudifMit`/acrylonitrile) can be used, although its poor color limits it tu d a i k colored applications. Other polymers used for modification are chlorinated polyethylene, acrylics, and acrylonitrile-butadiene-styrene (ABS) resins. 7 ircNC 000 4 ;!)ij u o cc !()()() < ifi n a < oi-j 2000 - O. o I 1_____ I______ J_______1___ _l_______ L_____ J_______ L TO UJ SO bO 70 PARTS !X)P/100 PARTS VYGEN 120 FIGURE 6. EFFECT OF OOP LEVEE ON ELONGATION PER CENT PARTS 1)017 100 PARTS VYGF.N 120 .lOt'.! 40 - O 80 - '"'O. 70 - oO - _J________I____ ,,_L_______L_ ,,___lIIi|| 8 0 40 SO b 0 70 PARTS DOP/100 PARTS VYCEN 120 L u b r iracion Vinyl is processed and formed by metallic parts which may be a set of rolls, a forming die, a mold, or some other device. During this processing, the vinyl must adhere to the metal so that the plastic draws in, fills, and flows with the forming surfaces. However, this adhesion must not be great enough to cause distortion wnc-n the an ic Le is removed from these metal surfaces. Adequate parting is obtained by including in the compound trace quantities of lubricants that act as metal release agents. The release agents are soluble to only a limited degree in the vinyl compound at the processing temperatures. Thus, minute particles of the release agent are deposited on the hot metal surfaces and form a s e nu continuous coating. Excessive quantities of the release agent shouLd be avoided to prevent exudation on the finished PVC surface. Exudation of lubricant appears after processing and is not only unsightly, but can interfere with the application of decorative finishes or subsequent dielectric heat sealing. Stearic acid is a common release agent, but metallic stearates, waxes, or poly ethylene have been used. Proper technology in the use of lubricants is an important factor in successful production of vinyl products. Pigmentation The growing use of PVC has been due in part to the color possibilities of the p1 a31ic. 9 \ 1: ! ' \ . 1 ` .1 11 i !; ' ; i <1 t L ' It i 11 p i l i > ! -j I ` 1 . 1 [ *1 L J 1 11 - 1 : 1 ' If 111 1' 1 ^ - t \ i " 11 1 i; i to i ; i h i; r i , in r a -> t. a i l h m n v , i i u i .. 1 u, < PV < ' li i - c t i ii li -I v l n g , ii [j f i i ,) i1 il ii i a l) i 1 i t. v is p r i)ii u i e d in -. i i o i s and ; e x - till'1 1 -villi 11 o 1 t f 1 unlimited 1 r c a L 1 v e s t y 1 1 11 s p 1) s 1 1 b 1 i 1 t 1 1' to -il e lir -11 L'lhM . rill- [) 1 .unit'll t, S lined mil a r, hr* acid rt'al .ildll t , stable to tile pnii l-isliii' t ciiipc r it urcs up to 100F, nuiimi grat ory , .md liglit stable. Tile1 pigments arc" dispersed to a fine particle sice by erindinc in a t hr e e - r o 1 1 paint mill with part, of the plasticizer. Satisfactory' pigments include titanium dioxide, ph t h a 1 or y an 1 rie blues and greens, and high tint carbon blacks. Fillers are often used for cost reduction. Finely divided calcium carbonate is most often used, but clay, asbestos, and other fillers are common. Certain electrical properties are improved through the use of f 1 1 I ' sFlame resistance is bolstered through the incorporation ~**C `nionv trioxide and phosphate plasticizers. Electrical propeicies are improved with the addition of calcined clay. B. Processes and Fabrication 1. Dryblending A PVC compound initially is a heterogeneous mixture of the manv components. The major ingredients are a PVC resin powder and a liquid plasticizer which must solvate the resin. The solvation rate of this type of system is time and temperature dependent. The most economical method of solvating the resin is through the use of inexpensive mixing equipment with large capacities. Thus, large stainless steel chambers jacketed for heating are used to churn, tumble, or agitate three to five thousand pounds of the compound. At this stage, only the colorant is omitted. The temper ature is maintained at 180 to 200F for about an hour. This equip ment is often a ribbon blender. 2. Hanbu ry1ng Part of the presolvated resin-plasticizer masterbatch from the preblender, together with the pigment paste, is fused into a homogeneous mass in an intensive shear internal mixer such as a Banbury. This machine consists of a two cylindered stator containing two powered rotors. Their operation is such that the plastic compound is sheared against and around the stator's surfaces. The stators and/or the rotors are heated to raise the temperature of the vijiyl compound to its fusing temperature between 300-350F. A plunger retains the compound within the -chambers and a sliding door iji the bottom of the chambers allows the fused homogetieous compound to be discharged. The capacity of production,size Banburys for the vinyl industry varies from a 110 to a 600 lb. batch delivered on five minute cycles. 3. Milling Normally, a Banbury batch is delivered to one or more 60" to 90" wide two-roll mills designed for high temperature operation. The 10 r-.i! r iLiiJf.l .ii' w li i |i [j t- ` i mi ; . .1 tii g 11 - f 11 i ' 1 H .i 11 In i ; % , ' i i ,, . : 'ill I l r *, . i 1 1 I Ml 1 !' I) i I ' 11 1 I "I j I i I ,1 t 11 I r M i n .1 , f 11 [ r 1 (i [ , a : 1 p; i ,t ii . i a asi t \ 1 , i II '1 i ' : ! 1) li r I 1 \ I1 I tin [i l .1 at i i i ii a : 1 !.! < ' a : p r i: ii e 1 i' [ iii i n i- ii w i d i Ii and g i u g e nl i Ii l t'kiii'M . I ii l a ribbon ilm L hr t` i ii ! i [ i.-t t 1 y lo a o a 1 o n ii a i or an r x r r u ii er in prai r i r,i 1 1 v an ideal p last. 10 a L a l r- , or ii may bn par I l ally r Led ami tod lo a d l c n r or p o L L o t. l l e r to make a reserve oompourid inventory I'm future p r o o e .a .a 1 n g . f. CaIende nng ' 1 A large percentage of the above mill-prepared vinyl plastic com pound is fed to a calender which converts the crudely shaped ribbon into continuous lengths of film, sheeting, or coating lor a sub strate (i.e,, woven cloth, knit fabrics, or paper, etc.) of surpris , hfe-", : i r 11 e widths and thicknesses. for example, a modern pu^t. . calender is capable of delivering a 0.0018" gauge film with a maximum variation in gauge of i 0.0001", Normally, film of this gauge can be more economically produced by extrusion, since a two million dollar calender train must have a high poundage output Lo justify its capital investment. A modern calender engineered for handling plastics has four cast chilled iron rolls mounted in a Z type frame so that the influences of forces on any one roll can affect only one adjacent roll. A roll with a working face of 66" width will be from 20" to 2-1" in diameter while a 96" width roll face will have from 30" to 36" in diameter. 1his calender will be automated both to control the gauge of the film and also to emboss, cool, and deliver the film to the packaging unit. These devices and their controls in the calender train repre sent an investment of a million dollars. The output production of a calender is dependent upon the gauge of the plastic delivered and generally falls In the range of 2000 to 3000 lbs. per hour for a 66" width machine. The ordinary plastic calender produces film hetween 0.003" and 0.005" gauges to be used for raincoats, shower or window curtains, aprons, baby pants, food covers, and similar articles. Film be tween 0.005" and 0.010" gauges is used for inflatable toys, air mattresses, industrial protective covering, and electrical tape. Sheeting between 0.016" and 0.022" is used for novelty purposes such as ladies handbags, belts, wallets, and briefcases. All of these gauges are used for coating fabrics or paper that are widely used in upholstery, rainwear, apparel, boat decking, shoe trimmings, book covers, and many other uses. Table 2 shows a typical formulation for a General Purpose Film. -11- I\ : i I '\ 1 K'll lliH I II I'll r j, u "i t- 1' l ! in Parts Re S L 11 P 1 a s t icuors: Processing aid' Stabiliser: Vygen 1 10 DOP (. r esv 1 diphenyl Mo numeric epoxy Stearic acid !ia-Cd phosphate p 1 a s t i c i 7. e r 100.00 37.00 8.00 r>. oo 0.2 5 2 , 00 Extrusion A second method for shaping a molten plastic into a desired shape is with an extruder. This device consists of a smooth bore cylinder with a close fitting worm screw rotating inside the cylinder. PVC compound as cold pellets, cold dry blended powder, or hot mill ribbon is fed to the extruder. It is homogeneously mixed and brought to its proper working viscosity for ultimate forming by the mechanical energy of the screw and the heat provided by the controlled temperature cylinder or barrel. The changed pitch of the screw at its end alters the screw's function from masticating and mixing to that of a positive displacement pump. The orifice or die mounted at the head of the screw is similar in shape to the desired product. The shaped extrudate is drawn in a measured degree from the die to the cooling medium, usually water. The die must be designed in such a fashion as to compensate for the change m dimensions and shape that this pull or draft exerts on the hot extrudate. Hie extruder can form flat film, sheeting, and coated products simi lar to the products of a calender and, in addition, make hollow articles and complex shapes impossible ro obtain from a calender. It is considerably less costly to install, but has only a small fraction of the capacity of a calender. Film as thin as 'T mil can be extruded by the blown film technique. A tube with a wall thickness of 0.012" is extruded. As the tube of hot plastic issues from the extruder, air is introduced inside the tube in sufficient quantity to expand the plastic to a 72" diameter cylinder. This simultaneously widens the film and reduces the gauge of the wall thickness. The percentage gauge tolerance of this film is far greater than the i 5% allowable for calendered film, but it is adequate for film used in packaging applications. An alternate procedure to blown film is the use of a slit die with dimensions approximately equal to that of the film desired. This die requires a high degree of engineering sophistication to produce uniform flow of the 1'VC plastic across wide widths and especially to prevent any sectional areas in the flow of the PVC plastic that are slow moving or "dead." This latter condition can lead to - 12 . 1 i, ; .i: 1 i i i i [i i ' ! i i'\1 111 ( 'i 1 :i r \ i t - i . r .i s Ill , ` : ' . '. il i , t i' ii , i i> 11 i - i'll'- p l a . t i i [ 11 'ii i ii g . Tin* t i 1 -n , [j r . t ,i n . t* J : * ,i i : 1 t ill To l *1. to ! . i - f t i) I !' 1 III I r ,in c ,i U g i* mil |t i) 1 1 1 1 1 t* i*. 1 L 11 !i 1 I) * u i 1 <1 [11 L 11 J f 1 11 M ( ) I 1 ! t t 11 t l ( tll'ij 11 1 [ ' 1 i 1 1 t. In U j M i 11 ' -.1 t t* tJ ^ LI 1 .-o I 1 1 [ t* 'It IS .1 fabric ill [I 11 p r I I -I (11) 1 1 |j l e W 1 t. h silt tilt-.1 t' \ I 1 11 s 1 o II .-Milk i a r [ o ii paper is n I I e n i n a I e d in this inaiiin.'r. The t: x l r ml e r i s used for making film," nionof i 1 jiiipii t strips, rods, tubing, hose, and profile .shapes surli as r e fr l ge i a t o r gasketing. Table 3 shows a Ly p l e a 1 - PVC refrigerator gasket, compound. Table 3 Extruded Refrigerator Gasket Parts Re sin: Plastici icrs: Filler: Stabilizer: Processing aid: Vygen 120 Polymeric epoxy plasticizer Polymeric plasticizer Calcium carbonate Ba-Cd lubricant 100.00 10. 00 80,00 25.00 1.50 0.2 5 The extruder is the universal device used for PVC coating of elec trical wire. In this latter application, the copper wire is pre heated, passed through a cross head on the extruder and carefully centered in a circular stream of extruding plastic so that an even coating surrounds the wire. The wire is pulled at a constant rate of speed and actually aids the production rate of the extruder in assisting the flow of the plastic. A cross head is a device for changing the flow of the plastic to a right, angle with its normal flow. The capacity of an extruder is rated by the diameter of its cylin der. Extruders are available in a range from lid" to 12" with the 2lA\ 4`A" , and 6" the most popular sizes. Their output capacities are about 175,500, and 1000 pounds per hour, respectively. The technology of the action of various thermoplastic materials during extrusion has received intensive study during the past five years and many plastics have had their behaviour reduced to mathematical terms. For example, screw design has been keyed to specific thermo plastic compositions and the proper ratio of the length of the screw to its diameter (C/D) has been established. Plastic extruders nor mally have an l./D of at least 20/1 and often are 30/1. As in the case of calendering, the process of cooling the extrudate and handling during postforming are highly developed operations which affect the surface characteristics, clarity, flatness, shape, and gauge of the product, a. Rigid Vinyl Rigid PVC contains only a small amount of plasticizer or none at all. Two types of rigid PVC are available. Type 1 possesses 13 11 ; [ . i f \ i i . i , a i i I ,s r , i 1 i i ' i i , ; am !l '!, I , A J .1 11 ll fill'.' i.-.il pi i t 1 f f - .'111 ,1 n. i : . , . p 1 1 1 -r - ill [' i` , up i > 2 0 i i i! t* [ h .i i ,1 l\pe i- 1 !u Linp.ii L s r [' 11 LT ' 1 ^ p ; 11 v id e il b \ i n e 1 i] -ion <> t i f r i 1 e mi li h < r . or in od i l \ l n '- o-, 1 1 o n g with b L a b i 1 \ L e [' s , I ; i 1 e r b, and ad ll 1 i vi'b, la b V L P d L 1 0 u o L F y p e 2 lb e a s1 e r and a u r t a r e d e 1 et t b a i e less o1 a p i o b 1 cm , Tv p e s 1 anti 2 PVC art" use d in idectrica 1 conduit, p l p e, con- s t r u c t ion panels, Lank linings, valves and skylight S , and man y other rigid a p p1 i cat ions. Table 1 shows the effect o f mo 1 e c ti 1 weight and ifsin modi t ier on t lie phy s l < a 1 propertie S of r i gi a PVC. The use of t h e ABS resin provides a s u b s L a n L i a 1 iiir r e a s e in impact resistance* Table 4 Elfect ot Molecular Weight and Modifying Re sin on Rigid PVC Properties Resin Vygen 65 Vygen 85 Vygen 120 ABS* Intr) Viscosity 0.70 0.80 1. 18 19 100 - - LOO - - Propertie s 3 , 1 00 - 4 70 * 30 S 70 30 Tensile Strength, psi Flexural Strength, ps L Flexural Modulus, psi 7,750 7,775 7,850 6,150 6, 250 11,750 12,000 1 2, 500 9,225 9, 60 0 4.2 x 105 4.2 x 105 4. 4 x 10 5 3.3 x 105 3.6 x 10 Notched Iz o d 7 7 0 F, ft. 1 b . /l n . 0.44 0 . 50 0.80 14.0 18.0 Heat Distortion 264 psi, C 10 mil deflection 60 mil deflection 6 9 69 7 5 6 b 7 2 75 7 6 80 74 78 Rockwell "R" Hardness 115 115 116 107 108 * Ac r y 1 o n i t r i 1 e - Bu t ad lene-Styrene resin b. Vinyl Fo am Vinyl foam may be prepared from suspension resin by extrusion Nitrogen compounds which decompose under heat are us ed to pro vide the gas needed for expansion , Th e decomposition temper* ature i s adj ustab 1 e by a post expansion technique. In t h 1 s process, the material is extruded at a temperature b e 1 ow th e b 1 owi "8 agent decomposition temperature ; subsequent expansion 14 I! I :1 i \ Mi 1 t 11 i i |) I) 11 11, i . f, I [ 1 *b . ! 1 " ' 1 tj * I " ' : 1 \ l > II [[ 1 J u .!, 'I , 1 t ( p) lb. c u . ! i ..I 111 h l a b e I 1 r 1 o T -1 I- ! ! 7 u ,iiii ,i be' p rob '! i i` il bydiicrt u x L r n s i o n jii<1 bln* ini' otMir 'impound within tbf barrel o 1' t lit: c\t. muIi1 r. K x p an l o n nmn , upon the cm <_ i n e ne i-" `>1 the i ompounJ from the extruder head. Closed i ell vinyl foams arc also made 1 r-oin blends oi vinyl and nitrile rubber. The pruper relationship must be maintained between the cure of the nitrile and the decomposition of the blowing agent, since the curing nitrile supports the cellular matrix. Too rapid a cure ieads to ruptured cells; too slow a cure results in lost gas, giving high densities. 1J roper balancing of the system gives densities as low as four to s;x pounds per cubic foot. 6. Blow Molding Blow molding is a we 11 -accepted process for the production of plastic bottles especially, but the use of vinyl in this process in the U.S.A, has not reached the volume which it enjoys in Europe. The slower growth of blown PVC bottles in this country has been due to a lack of stabilizers which will permit clarity of the finished bottle and still pass the tojucity requirements of the Pood and Drug Administration. Blown l1 VC bottles do show superior properties to polyethylene types. In addition to tiigh clarity and good oil resistance, PVC bottles have 1/10 the oxygen permeability of similar PE bottles. Due to the high rigidity of PVC, thinner walls can be used. An extruder is the source of the prepared hot plastic compound for blow molding. In this process a cylinder of hot plastic falls in a vertical position below the extruder head and between the opening of a split mold. The split mold closes to pinch the ends of the plastic, making a sealed tube. A hypodermic needle pene trates the interior of the sealed Lube, and pressurized air is injected to expand the sealed tube until it fills the mold cavity. The cold or relatively cold mold converts the plastic to its hardened condition in a few seconds. The mold opens and discharges the molded object, and the cycle repeats itself automatically. The formed object may be a waste basket, an automobile arm rest, or a part of a toy doll, although PVC bottles have one of the most interesting possibilities for future markets. This is an intricate art requiring extremely accurate control of the temperature (i.e., viscosity) of the PVC compound. Clarity is achieved through proper compounding and is based mainly on the stabilizer used, although the chilling rate of the hot article, particularly bottles, is also important. A rapid chill usually improves the clarity. Some degree of clarity is lost due to the increased molecular weight needed for impact strength. IS Gtric Of jQ.-  :r 1 . I' [ .1 l li( ' *L ' i ii : i . - ,hu i i one! !is 1 1) \ 11 . p r i "i ,11 i 1 \ /.mu ,init call i urn t \ p , il w w < v e i , Ui r - c m ,i t r i i ,i 1 lt L v ij If-,-, p i o I. i -1 I i o n ,i t [) [ o i' (' s s i n g t rm p e - ii t u r r t h a n the Imti lira-1 Jilnmn! ,ui ti tin t V [if s . 1 h e s u (' r e s , o 1 [' V ( blow molding in l.u r o p e is due to the >i , e of di-uclyl tin r o m po u n d s , w`ti i c h arc ,1 s V c L u nn i c p I ;i b 1 c in this i oimr ry . As more acceptable stabilizers are developed, a large market will be created lor PVC bottles where other thermoplastics- are unaccept able. The future should see PVC bottles used to package gasoline, motor and mineral oils, polishes and insecticides, cosmetics, per fumes, disinfectants, detergents, foods, and soft drinks. 7. Compression Molding The molders ol phonograph player records consume large tonnage of vinyl compounds for compression molding of their disks. They use a low molecular weight homopolviner or copolymer resin for this purpose and the application is a specialized industry. Clear rigid sheeting as windows lor instrument panels, flexible clear sheeting as rear windows in automobiles and novelty applications, are also press molded. 8. [nj ec 11on Molding PVC compounds are used to a limited extent in injection molded parts. The rotating piasticating screw plunger type of machine definitely preferred in processing vinyl. is 9. Fluidized Bed Coatings The fluidized bed coating technique is excellent for coating intricate metallic parts. This can be done with a powder blend containing all plasticizers, pigments, and stabilizers. The more popular and successful method is to fuse the powder blend and to then pulverize it into a fine powder. The coating technique is to heat the part to be coated to a temper ature in excess of 450F. The healed part is then suspended in an environment of the powdered resin blend which is fluidized with a stream of air. The thickness of the fused layers can be controlled very , accC urately. coatings. Hepeated dippings can build up thick and uniform 10, Contour Forming Irregular formed parts, such as automotive crash pads, are usually made from flat sheets which are post forme d to the desired shape. The most common pTocedure is to use the vacuum forming system. In this technique the flat sheeting is softened by radiant heat to the forming temperature. The preheated sheet is then placed over 16 i \ .1 l*n III t i r [j r i- ii r t- < a u i m , u i -a lit' i Ii ci- 'ini N the ; mi v i ii < < i ""> i !i i i` i h t mu I ii it-, It e a t rapidly and i a n In- l i 1 t , >1 1 ,i i. r . raid the a 1 inn p K - ; . ra* -uni 1 l 1 I lilt1 i - ,: i , i u i a , tin- v i ii v 1 dir e l i u , i* i Dill the -I.o 1 d a m i n n l > i) r I wo \n ,il UTiuL l ve type of molding to vacuum to distort, the hot vinyl sheering into a is equipped with holes for the escape o 1 The use of mat cited male and female molds the closest dimensional tolerance. forming uses air pressure female mold providing it air entrapped in the molds. results in products with 1 1 . Assembly of PVC Products PVC products are readily cut to si/.e in multiple layers by the commonly employed motor driven circular knives or by cutting with pattern shaped dies. Dielectric heat sealing is often used to seal PVC films and flexible sheets. In the process, the PVC. to be joined is placed between two electrode sealing bars which transmit a high frequency current to the PVC and exert the required pressure on it. Ifeat provided by friction from shifting of the polar chains within the material causes the films to flow together and seal. The resultant seams have bond strengths equal to the strength of the goods. The use of recommended solvent cements to make assemblies is as satisfactory as dielectric sealing and are used for large objects such as in tent-making or swimming pools. Fabric backed or sup ported PVC products are sewn with thread as in upholstery assembly. C. Decorative Effects* 1 2 A high percentage of vinyl resin products are consumer items and depend ent upon their attractive surface appearance and style to sell. These effects are obtained by either embossing or printing the colored surface, or both, 1. Embossing Embossing of the plastic is achieved using steel rolls engraved with impressions that will give a pleasing appearance. These rolls are mounted over rubber backup rolls in the calender or extruder train as close to the forming orifice as possible. At this loca tion, the plastic sheet is in its ideal rheological condition to form into and permanently retain the configuration of the delicate engraving pattern of the embossing roll. 2. Printing The majority of automotive upholstery is currently finished in metallic effects across the entire surface. These chrome tones cannot be obtained directly from the calender since the aluminum flake does not have an opportunity to "leaf" as it does in a highly 17 ' : i i i . i - ii i ' i `1 t` .! r ') 1 o g r a v il ; ! p r i hi tr I 1\-n t . ! r '. i - '' -: r "< , in e ' . ' .1 ' - i ); : birr ,: i i -1,. 1 h e : a b r n. is , u r, c q u cn t i V dr i <"! De .i L g 11 print t a 1 1 3 lilt') 1 A . ) ' ju e s . I'll t: r e a r tj the de l 1 t a l o and n b L 1 e sh ad r ug s a s a o c l 11 c 0 i i r'ti high grade leather' e f f e c L .-o and lh>- gaudy and often in u 1 c l - c o i o i i t in. r s of houseware and app a r e 1 m a t o - rials. These ar e a 1 s o a p 11 1 i e i 1 on rotogravure print m a c h l ii e 3 equipped with print rolls having the appropriate design engraved into their surface. Ar times, print machines must have up to eight stations applying different colors which print in register to make a flower reproduction. D. Mixing and Processing of PI as t. iso 1 Resins* 1 So fir we have discussed how PVC suspension produced resins are com pounded and processed. Plantisol resins are handled and processed in an entirely different manner. Plastisol compounds are made so that when the resin is blended with a liquid plasticizer, the mixture is in the form of a fluid. Plastisol resins are often termed "stir-in resins," for a common method of blending a plastisol resin formulation is the use of a simple agitator. Hl-shear mixers are quite common, although practically any method by which the resin can he dispersed uniformly in the plasticizer and/or solvents is acceptable. In the blending process, the liquids in a formulation are charged to a vessel and agitated until mixed. Then the plastisol resin and other powders are added gradually under agitation until all materials are charged and a uniform liquid, called a "plastisol," is produced. When organic solvents are included in the formulation, the iiquid is termed an "organosol." , The solvents are used as viscosity reducing agents. The rheology of these liquid systems is quite critical, since they are processed by methods where the flowability must be closely controlled, Plastisol s are used in the following ways: 1. Dip Coating A widely used process is dip coating. In this process, an article, such as a wire dish drainer, is dipped into the plastisol arid re moved. The coating is then fused onto the dipped article in forced draft ovens. When an organosol is used, the heating of the article must be carried out in two stages. The first stage consists of evaporation of the solvent under low heat; the second stage consists of fusion of the vinyl. In this way, surface imperfections due to boiling solvent during fusion are eliminated. Usually, a solvent recovery system is installed in plants rising organosols for reasons of economy. In a variation of this process, cotton gloves on metal hands are dip conted in order to impart chemical protection and solvent resistance to work gloves. Articles too large for dip coating may be sprayed with plastisol and subsequently fused. 18 \t,, > ! u 11 'mi ! 1 i i; \i is, in j -,011m, liii- i - - . i i p i i > i1 o -5 s o 1 dip i i j ,i 1 i n 111 ! il L -J (1 I 11 l l- i till' }J 1 '1 1 1 M I 5 |J , > 11 ' ,i 1 II I II ,1 h 0 ,1 t t`d 1110 i 11 , The mold L t 11 o il 1 n v o r t I- d and nnU ,i nul i nil i t tin- gelled v i n v l rniijiii L a ilio mold. Fusion and s L r i [i p i n g u 1 liio article from the mold lomplctc the ptocess. Boots are maOc liy such a technique. The main rest i iction o 1 slush in o i d i n g i s t Ii a t, the article may t have at least one sizeable opening to the interior to permit filling and . emptying the mold ot plant, i oi 1 . 3 . Ho t Jt l iinal Molding Holalional molding is much like slush molding, except that there need be no opening in the article for the introduction of plastisol It. is used for complex shapes like dolls' heads, arms, etc. It is ; Iso use.d for play balls, footballs, and basketballs. In the tech nique, a quantity of plastisol is poured into a mold, the mold is closed and rotated in three dimensions while heat is used to fuse the [ ormelation inside. Temperatures must be controlled so as to permit even fusion and uniform flow characteristics, 4. HVC Foams PVC f oarns are easily prepared from plastisols. Either a chemical which decomposes under heat or a mechanical entrapment of gas may be used. The plastisol is often laid down as a thin coating over another vinyl layer which may or may not be fused. When blown, the combination is effectively used as an insulating material resembling leather for use in outerwear. The areas of cushioning and insulating are more often captured by urethanes or polystyrenes. 19 A ; 't - i . - , :\ * A i k , s ( h L 1 il k n l- '' !i I , l. a I v i i: 1 v a [' r ' ! , \ i ,, v ! 11: i 1 :a c r 3 , W 1 I i v ami Snn.-i , New \ , i Bernhardt, Enir = t 14 59 P r o r e , s l n g o I Plastic M a t e r l a 1 s , Reinhold, New Yarn, 4. Cope, Dwight, Plastic Materials, Goodheart-Wilcox Co, , Chic ago, 19 5 h 5. Esterez, J. M. J. and Powell, 0. C. , Manipulation of Thermoplastic -Sheet, Rod and Tube, llilfe & Sons Ltd., London, 19t>0 6. Simonds, Herbert Rumsey, Source Rook of the New Plastics, Reinhold, New Yo rk, 1959 7 . K r a d o s , Joel ( E d i r_o p- ^^inde,~n Plastics Encyclopedia for 1964, V o 1 . 41/ No. 1A, Hildreth i;: :n>_., Bii.stol, Connecticut, 1963 8. SPI Plastics Engineering Handbook, I960 1 . !' .1 1 I. ,'[ , V >. ' , I i .1 ! k , I II I 11 t I 1 ,1 I l !i ' T 1 1 I 'll) ;i i , I'n'., ! `t ,*11 ) , p!' . ' V - j "j NV * \ ! - : I ' ' (' 'I A ; , 2 . IV r 11 n a 1 ( Viunm n i i ,i i i n , ! n ; n u I'ai i, i dr , \h L n b u 1 .) , l Vi u 3. Scliorh, F.. I1., " A< c L \ 1 n c from H y ii r o c nr b o n s , " Un i v ' - i t y of Te x as Publication, No. SOIL (June L 950), pp. 3 L- 41 4. Bixler, ti. and C.W. Coberly, Induat rial & Engineering Chenn jiry, Vol. J. 5 No. 12 (December 1953), p p. 2596 - 2606 5. Ibid 1, pp. 37-39 6. "Petrochemical Handbook," Petroleum Refine.r, Vol. 38, No. 1 1 ( 1 959 ), p, 202 7. Union Carbide Jl,c- ^-ni Analysis 8. Kennedy and Holm, " Di v i ny 1 sulphi tie in Commercial Acetylene," Canadian Chemistry & Process Industries (October 1959) 9. Ibid 6, p. 298 10. Monsanto U. S. Patent 757,661 (1954) 11. Wesselbolt, Woods, Smith, "Vinyl Chloride from Acetylene and Hydrogen Chloride: Catalytic Rate Studies," A,I.Ch.E Journal, Vol. 5. (September 1959), pp. 351-366 12. Frescoln, The Production of Vinyl Chloride in a Fluidized Catalyst Red, Ph. D. Thesis, Case Institute of Technology (1951) 13. Locher, Trans. Faraday Society, Vol. 58 (1962) 14. Ibid. 6, p. 238 15. Ibid. 1, p. 367-368 16. LaChnmca e L'lndustria 33 (1951), pp, 613-619 17. "Petrochemical Handbook," Petroleum Refiner, Vol. 34, No. 12 (1955), p. 1960 18. Ibid 15 19. "Industrial Vinyl Chloride," The Chemical Age, (December 1951), pp. 801-803 20. Ibid 15 21. Doraiswany, L. K. P. H. Brohme, M. V. Pai, and S. Chidambarum, "A Study of the Kinetics and Thermodynamics of a Reaction Producing Vinyl Chloride," J. Chem, & F.ngi nee ring Data (New York: Re in hold Publishing Company, 1962 ) 22. Barton and Rowlett, J. Chem. Son, (1949), p. 155 39 " 1V ( i ' x i', 'i: i -I ! I Ian u 1m)d k , p p i1 v ' 10 IV i . i I i liin Hi t i n , \ ;i 1 l 2 , Nn i 1 i i, 2 1 Be 1 a 1 U 111 P at I - II t 1 9 8 , 2 J 1 , Soc 1 t- L c Be 1 ge Dr 1. ' \ /. n [ r r t d e , D r Oil 111 t n ('him Ij ij 1 -> lu M.i i 1 > ( lOpO ) 25. Chemical Week, (March 18, 1461), p. 4l 26. "Vinyl Chloride trom Dilute Amlylene (janes," I inlusr i i al & Engineering Chemistry (April 1954), p. 623 27. "OxychUrination," Chemical Week (August 22, 1964), p. 94 28. "MCI: PPG Finds Possible Way Out of By-Product Glut," Oil, Paint, & Drug Be porter (September 21, 19b2) 29. Ibid 27, p. 99 30. "A Package Deal for Making Vinyl Chloride," European Chemical News (March 20, 1964), p. 29-31 31. Ibid 27 32. Oil, Paint, & Drug Reporter (August 10, 1964), p. 24 33. Ibid 30