ZINC CHEMICALS IN PLASTICS SYSTEMS - Industrial & Engineering

ZINC CHEMICALS IN PLASTICS SYSTEMS. J. George. Bilek, Valerie. Kollonitsch, and Charles H. Kline. Ind. Eng. Chem. , 1966, 58 (5), pp 28–36. DOI: 10...
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polystyrene (749),and sodium phenyl phosphinate in nylon (68).

f the metallic elements whose compounds find application as plastics additives, zinc is probably the most widely used. Zinc chemicals are employed in a variety of resin systems as activators, catalysts, stabilizers, fillers, pigments, lubricants, fungistats, and dyeing aids. In a few experimental polymers, zinc actually forms part of the polymer structure. I n some applications zinc compounds are used for their unique intrinsic propertieefor example, the strong ultraviolet absorption of zinc oxide. In other uses zinc is often merely a convenient metal to use with a functional moiety such as a fatty acid. In either case, zinc has advantages over other metals of stability, safety, freedom h m color, mild reactivity, moderate molecular weight, and relatively low cost.

0

Plastic Foams

More recently, zinc chemicals have been widely adopted as processing aids in the production of plastic foams for packaging, insulation, cushions, mattresses, and buoyant materials. Foams are made either by mechanically incorporating air or other gases into polymer systems or by induding in the formulation 'a chemical blowing agent which will decompose to a gas on heating or by chemical reaction. A common blowing agent is azobisformamide, N H r C O - N = N - C O NH2, which decomposes on heating to release nitrogen. The decomposition of azobisformamide starts at about 20O0 C. (65, 709). Zinc oxide, zinc soaps, and similar compounds of other metals at 1 to 4 p.h.r. serve as activators (often called kickers or promoters) to lower the decomposition temperature. The exact temperature depends on the type and amount of activator, plasticizer, and such deactivating components as chelating agents,

Mold Lubricanlr

The oldest use for zinc chemicals in plastics is the incorporation of soaps into resins to give good flow and release of finished parts from the mold. Because of its high lubricity, zinc stearate is the most common metal

n

I

1 S I

Ir

soap used as a mold lubricant (767). U.S.consumption in this use is about 2 million pounds a year. Zinc stearate is often added to the major thermosetting resins, particularly phenolics (29,63, 799),ureas and melamines (748, 778, 799),and polyesters (29,749). I t is also sometimes used in formulations for such thermoplastic resins as polyethylene (726, 729),polystyrene (77,760, 787), and nylon (68, 735). In vinyls, zinc stearate or other metal soaps in the stabilizer formulation also act as mold lubricants. The amount of zinc stearate in molding compounds rarely exceeds one part per hundred parts resin (p.h.r.). For example, phenolic and polyester premix formulations use 1.25 p.h.r. (29). However, in polystyrene, the level of zinc stearate in the formulation is held below 0.1 to 0.2 p.h.r. to avoid cloudiness and haze in the molded parts (78, 760). Most commonly, zinc stearate is used alone. However, some recent patents disclose its use in mixtures with such other additives as plyethylene glycol in polyethylene (726), polyethylene glycol monostearate in 28

INDUSTRIAL A N D ENGINEERING CHEMISTRY

imines, or vulcanization accelerators (65, 797, 794). Some typical decomposition temperatures for azobisformamide (ABFA) alone and in poly(viny1 chloride) (PVC)systems are listed in Table I. In vinyl foams, zinc oxide, zinc stearate, and other zinc soaps are effective, nontoxic, nonstaining activators (65, 797,796). Cadmium and lead compounds are also effective, but both metals are toxic, while lead also TABLE 1.

EFFECT OF ZINC COMPOUNDS ON ABFA DECOMPOSITION TEMPERATUREm

+

ABFA plasticizer ABFA plasticizer zinc litcarate ABFA ~lanicizer nnc oxide PVC ABFA plasticizer No activator Cadmium-barium stabilizer Zinc or lead activator

+ +.

+

e

(65, 797).

+

++

180-210 150-160 130-155

190-200

160

stains the foam in the presence of hydrogen sulfide. Frequently, zinc soaps or zinc oxide is used in combination with other metal chemicals to serve as both stabilizers and activators. Some common combinations are barium-cadmium-zinc, barium-zinc, and calcium-zinc soaps and calcium-zinc-cadmium soaps plus zinc oxide (65, 709, 747). A number of commercial zinc stabilizers are recommended for foamed vinyls at concentrations from 0.5 to 4.0 p.h.r. Specially formulated activators containing zinc have recently been introduced that make possible the production of low-density vinyl foams at less cost than with conventional stabilizers (737, 732). Cross-linking strengthens plastic foams and gives them much greater stability to heat. Zinc compounds are used to catalyze the cross-linking reaction in several types of foams. For example, in polyurethane systems, low-density, fine cell foams can be produced by reacting the diisocyanate components with polyesters, polyester amides, or polyethers in the presence of zinc oxide and water (773). Zinc oxide is used at a level of 10% by

weight of polyester. It appears to be a better crosslinking agent than the tertiary amines commonly used. Rigid poly(viny1 chloride) foams are made by crosslinking epoxidized oil plasticizers with zinc oxide. Here organic amines would react explosively with the nitroso blowing agent recommended for this system. A typical formulation is resin 100 parts, epoxy plasticizer 65 parts, and zinc oxide 25 parts (52). In cross-linked polyethylene foam, zinc oxide is sometimes incorporated in the pigment system (709, 770). Structural properties of foams are sometimes improved by zinc additives. For example, polyethylene compositions for foaming by direct extrusion can be formulated with only the resin and blowing agent (770). However, addition of 1.0 p.h.r. of zinc stearate (or similar soaps of other metals) gives a finer, more even cell structure and a smoother surface (78). Similarly, the load-bearing properties of polyurethane foams exposed to moist environments can be improved by adding zinc, cadmium, or lead salts of substituted dithiocarbamates at 0.05 to 0.1% by weight of the poly01 component (727).

Vinyl Yclbilization

PVC and its copolymers must be stabilized against degradation by heat and light, both in service and particularly in processing, when the resins are exposed to elevated temperatures for extended periods. Degradation greatly reduces the mechanical properties of the resin and destroys its clarity and color. Initially hydrogen chloride is split off to leave an unsaturated chain, which is then further degraded by oxidation and crosslinking. Degradation can be largely prevented by the use of metallic soaps, phenates, phosphites, and other salts as stabilizers. Their action apparently results from the replacement of labile chlorine atoms in the polymer by the carboxylic acid group from the metal salt. The ester thus formed is more stable than the original chloride. Labile chlorine atoms are generally attached to tertiary carbon atoms or to carbon atoms immediately adjacent to tertiary carbon or double bonds (allylic chlorine) (58,59).

Zinc soaps alone are not good primary stabilizers, apparently because they are readily converted by the hydrogen chloride evolved from the resin to zinc chloride, which functions as a Lewis acid to catalyze further degradation. When vinyl resins are processed at elevated temperatures with zinc soaps alone, the resin maintains excellent color and clarity for a period, but then suddenly turns black within a few seconds. The phenomenon is so rapid that it is referred to as catastrophic degradation (89). However, zinc soaps have proved to be highly effective secondary stabilizers, primarily in conjunction with barium and cadmium soaps, and also with calcium and lead soaps. As secondary stabilizers zinc soaps have a number of advantages: -In formulations with barium and cadmium soaps, they prevent atmospheric staining by sulfur compounds. They also prevent green staining by copper. -They improve the clarity and color and reduce VOL 5 8

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plateout of PVC resins stabilized with barium and cadmium. -They improve the stabilization of highly filled PVC compounds, particularly those filled with ground limestone and clay. -By partial substitution of cheaper zinc for the more expensive cadmium, the cost of stabilization is reduced and the use of a more readily available and less critical metal in times of shortage is made possible ( 7 75). -Because zinc is nontoxic, its soaps can be used with calcium soaps in stabilizers for food packaging (40). A number of calcium-zinc stabilizers are approved by the U. S. Food & Drug Administration. The chief potential competitors to zinc in these applications are the dioctyltin stabilizers recently approved for food use in Germany (88). --In plastisols, zinc-containing stabilizers minimize increases in viscosity and do not retard the release of entrained air. PVC resins differ widely in their tolerance to zinc. Homopolymers generally have considerably greater tolerance than copolymers. However, even within a given type of resin, zinc tolerance varies from manufacturer to manufacturer, apparently because of differences in chain branching and the type of suspending agent and catalyst used in manufacture. Because of the practical importance of zinc-containing stabilizers, leading stabilizer manufacturers classify commercial PVC resins by their zinc tolerance ( 2 ) . In many stabilizer formulations zinc stearate demonstrates synergistic effects with barium, cadmium, calcium, and lead soaps (40, 777, 180). In modern practice, mixed stabilizers are generally used. These contain metal soaps or other salts, epoxy compounds such as epoxidized soybean oils or derivatives of cyclohexene oxide, and organic phosphites-for example, triphenyl phosphite. The epoxy compounds improve light stability, and the phosphites apparently chelate metal ions that might otherwise form undesirable acid chlorides. The auxiliary components also display synergistic effects. Figure 1 demonstrates that color formation of PVC at 160' C. can be most successfully retarded with mixtures containing barium, cadmium, and zinc soaps and an auxiliary phosphite inhibitor. Without the zinc and the inhibitor there is little stabilization against discoloration (44). Stabilizer formulations often contain mixed metal soaps at up to 5 p.h.r., epoxy compounds at 5 to 15 p.h.r., chelators at 1 p.h.r., and antioxidants at around 0.5 p.h.r. Some typical formulations are listed in Table 11. The content of zinc soap in the mixed metal soaps is generally 10% or less, although calcium-zinc mixtures sometimes contain higher amounts of the zinc soap. On a resin basis, the concentration of zinc soap ranges between 0.2 and 0.8 p.h.r., and sometimes goes over l p.h.r. I t averages about 0.5 p.h.r. The zinc soaps 30

INDUSTRIAL A N D ENGINEERING CHEMISTRY

-

10.' mole psrrent Sta bilizar$ Bo Cd Zn

6 io

Minutes to color formation at 160" C.

40

do

& II b l l i o l i 0 IiO 160

7 4 3

'0

9 6 -

10

11 7 3

9 6-

- 0 - 0

---

-

'

=

I

0

Figure 7. Efect of zinc on stabilization of poly(viny1 chloride) film (44). Zinc compounds make good secondary stabilizers for vinyls

TABLE II. SOME TYPICAL VINYL STABILIZER MIXTURES CONTAINING ZINC

Content, P.H.R.

~

Comfionents Barium stearate Zinc stearate Epoxy compound Chelator

2.75 0.25 5-7 1

Calcium stearate Zinc stearate Epoxy compound

2.75 0.25 5-7

Coprecipitated strontium-zinc laurate Epoxy compound

2

Calcium benzoate Zinc stearate Epoxy compound Sorbitol Antioxidant

2.5 1 5 0.4 0.1

Barium-cadmium mixture Zinc 2-ethyl hexoate

5

Comments

Reference

Nonstaining in sulfur. .41so good for high-speed calendering stock FDA approved nontoxic combination for focd packaging For suspensionor emulsiontype Polymers Nontoxic formulation

(137, 738)

Nontoxic formulation for calendering or extrusion Nonstaining in sulfur. Good air release properties in organosols, plastisols Slush molding rainboots

(737, 738)

( 737)

(40)

( 739)

( 759)

(47)

commonly used are the stearate, laurate, and 2-ethylhexoate (octoate). Zinc phenate is also reportedly used. The solid stearate is an extremely efficient lubricant, but is less compatible with resin formulations than the liquid 2-ethylhexoate. Zinc laurate is generally available in mixed soaps. The recent patent literature discloses a number of novel zinc stabilizer formulations. For example, a

mixture of zinc and potassium 2-ethylhexoates is claimed to be effective at the extremely low concentration of 0.03 p.h.r. ; such low concentrations improve clarity and prevent increases in resin viscosity (37). Some other effective combinations are listed in Table 111. Examination of suppliers’ literature indicates that between one third and one half of all commercial PVC stabilizers contain zinc. Total consumption of zinc soaps in these products is approximately 2 million pounds a year. Recent reviews of vinyl stabilizers are given in references 35, 40, 774, 775, 777, 778, 737-747, 759, 777, and 7 72. Ultraviolet Stabilization

Zinc oxide has the greatest ultraviolet absorption of any pigment commercially available (782). Although it has long been used for stabilization against ultraviolet radiation in paints and rubber, it has only recently been considered for this purpose in plastics. Because of current interest in exterior plastics for building, several resin manufacturers are now studying effects of zinc oxide in vinyl, polyester, and other resins for outdoor use. Zinc oxide is also used in some highly filled vinyl floor tile for ultraviolet stabilization. A recent patent claims use of zinc oxide or sulfide as a light stabilizer in

TABLE l t l . SOME RECENTLY DISCLOSED ZINC STABILIZER FORMULATIONS FOR PVC

Zinc Chemicals

Other Components

Soaps (from edible oils)

Ca benzoate sorbitol Ca benzoate glycerol K soaps chelator Mg soap mannitol Ca ricinoleate epoxy Stearyl thioElycolate -. epoxy Phenol chelator K 2-ethvl hexoate 4-chelator BaO pentaerythritol BaClz pentaerythritol epoxy BaO pentaerythritol Ca naphthenate epoxy chelator

++

2-Ethyl hexoate

Reference

+ +

+ +

+

Chloride Oxide Naphthenate Diheptylphenyl phosphate Laurate, dilauroyl zinc, zinc deriv. of dodecanethiol, etc. Epoxy oleate Soaps of epoxy fatty acids Laurate Thio-&naphthol) Soaps of ether deriv. of lower fatty acids Salt of thiodiethylenebis-0-carboxy acrylate Salt of maleic acid monoesters Benzoate

++ +

+

+

+

EPOXY Unsaturated terpene mercaptan

+

Ca epoxy oleate Soaps, branched fatty acids, or metal phenolates Li and Mg soaps of epoxy fatty acids

+

Stabilization of Polyoleflns, Acrylics, and Other Resins

Several zinc compounds are reported to function as stabilizers for polyethylene and polypropylene, particularly against heat. For example, zinc diisopropyl dithiophosphate (ZDD) gives good high-temperature protection to polypropylene (72) and polyethylene (73). Zinc diethyl dithiocarbamate is also reported to be a good heat stabilizer for polyethylene (73). The concentration of these additives is below 1%. Various mixed stabilizers have been proposed that contain zinc oxide, stearate, or other salts of organic acids plus antioxidants and other components. A number of these are listed in Table IV. In several formulations the zinc oxide probably functions as an ultraviolet absorber. Zinc stearate, which is a moderate heat stabilizer when used alone (70), decreases the viscosity of molten polyethylene without otherwise affecting its desirable properties (726). A threefold increase in melt index can be obtained by adding a zinc soap, such as zinc stearate, palmitate, or myristate, to the resin. The soaps are used in concentrations of 0.25 to 6.0% and preferably between 0.8 and 2.5y0 by weight of the polymer. Up to 40% of the zinc soap can be replaced by the free fatty acid. Mixtures containing zinc compounds are good color stabilizers for acrylonitrile homopolymers and copolymers for fibers, coatings, or molding compositions. The zinc compounds include zinc formaldehyde sulfoxylate (79, 90), zinc hydrosulfite (80), and zinc diacetyl dithiophosphate (97,92). The compounds are always used in combination with an acid, such as sulfuric, sulfamic, oxalic, phosphoric, benzenephosphonic, or phosphonous acid. Sodium formaldehyde sulfoxylate (97) and formaldehyde (80, 92) can also be included. The additives are used in equal amounts in total concentrations ranging from 0.01 to 3.0%. Acrylic fibers can be stabilized by adding zinc acetate or oxalate to the finishing bath (784), and acrylonitrile graft polymers by organic ultraviolet absorbers plus 1yo zinc sulfide (74). Polystyrene can be stabilized against light deterioration with ethylene or propylene oxide adducts of organic compounds. Stabilization is further increased in the presence of zinc stearate (69). Thus, molded polystyrene parts containing 0.5% diethylene glycol mono-

AUTHORS 3.

Ca laurate

Alkali metal soap chelator

polyolefins and such copolymers as ethylene-vinyl acetate (728).

+ poly01

George Bilek is project manager, chemistry, f o r the International Lead Zinc Research Organization, Inc., New York. ILZRO, as the organization is commonly called, is an international association of lead and zinc producers, currently conducting research on these metals on three continents. Valerie Kollonitsch is technical information specialist and Charles H. Kline is president of C. H. Kline &? Co., Inc., Pompton Plains, N . J. VOL. 5 8

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Zinc dust, foil, and flakes impart strength, hardness, and decorative pluses butyl ether plus 0.002% zinc stearate showed much less discoloration after exposure to radiation from the quartz lamp than those made without zinc soap. The thermal stability of perfluorochlorocarbon plastics can be improved by adding the oxides or sulfides of zinc, cadmium, and mercury at concentrations of 0.2 to 2.0% for molding compounds and 3 to 7% for dispersions. Zinc oxide is one of the best stabilizers tested (87). Polyvinyl pyrrolidone has been successfully stabilized with 0.1 to 5.0% zinc formaldehyde sulfoxylate (45); polycarbonate resins with up to 3.0% crystalline zinc silicate (93) ; and poly(viny1 acetate) spinning solutions with zinc sulfate (156). Functional Pigments

Zinc dust added to polyester resins in high concentrations (400 p.h.r.) gives high hardness, good mechanical properties, and low abrasion in molds for plastic parts. Polyvinyl alcohol films used as parting agents for the molded pieces adhere well to the zinc-rich resin. Abrasion is considerably less than in similar systems filled with calcium carbonate, silica, or iron (775). In lower loadings metallic zinc increases the impact strength and heat distortion temperature of vinyl, styrene, and acrylic resins (4); the heat conductivity of polybutenes (7); and the working life of plastic pipe (793). I n epoxy adhesives, zinc dust contributes to greatly increased shear strength ( 7 7 I b ) . A typical formulation is shown in Table V. The excellent performance of zinc dust is apparently caused in part by its catalytic effect on the resin. For decorative effects, zinc foil and flakes are sometimes incorporated in resins for plastic housewares and toys to give a tinsel appearance. Zinc and copper-zinc alloys are also used in powdered form as metallic pigments for plastics (62). Zinc oxide is also used as a filler at levels up to 30 p.h.r., primarily to give high hardness (768b). Heat stability, electrical conductivity, impact strength, elastic recovery, water resistance, or other properties are sometimes also improved. For example, silicone resins loaded with up to 95Yc zinc oxide are reported stable up to 2000O C . (197). Similarly, addition of 4 to GYc zinc oxide improves the thermal conductivity of cross-linked polyethylene for electrical insulation ( 787). However, zinc oxide is not recommended for acrylics to be used in acid atmospheres (770). Among the other systems in which the addition of zinc oxide has been studied are alkyd resins (24, 779))ethyl cellulose (768~7))shellac (24), polyethylene plus vinylsilane-coated fillers (95), silicone insulating coatings for polyester film (ZO), and irradiated polybutenes (203). Zinc chromate gives improved corrosion resistance in epoxy laminates ( 1 7 7c) and zinc sulfide can be used as a phosphorescent pigment (62) or to enhance photocon32

INDUSTRIAL AND ENGINEERING CHEMISTRY

ductivity (106). Zinc stearate can be used as a temporary filler in the production of porous polyethylene for filters. Polyethylene powder is mixed with 10% talc and 10% zinc stearate, molded, and sintered. The zinc stearate is removed with concentrated phosphoric acid (764). Curing and Cross-linking Agents

Zinc oxide serves as a catalyst for various cross-linking reactions, usually to produce rubberlike materials froin various copolymers. Generally, the cross-linked product has better mechanical properties, improved chemical resistance, and greater stability. Some recent examples are chlorinated polyolefins (120), copolymers of ozonized polyethylene (or polystyrene) with acrylic acid (145), and copolymers of alkyl acrylates and unsaturated acids to elastomers (26). In a similar application liquid copolymers of butadiene and methacrylic acid are converted by zinc oxide to stiff, puttylike materials suitable for centers of golf balls. Such conventional cross-linking agents as sulfur give flexible rubbers (37). These reactions are carried out at 50' to 170' C. with 5 to 10% of zinc oxide. Higher levels of zinc oxide are occasionally used. Sometimes it is coated with zinc sulfate or phosphate, as in the preparation of elastomers from organic acids (25). Zinc oxide is used as a curing catalyst for such resins as alkyds (768c), phenolic-polyvinyl butyral and phenolic-tung oil mixtures (24), and ozonized polychloroprene (46). I t also functions as an accelerator or activator for peroxide curing agents. For example, poly(vinyl chloride) is cross-linked with pentaerythritol by dicumyl peroxide in the presence of 1 p.h.r. zinc oxide. Without the zinc oxide the reaction is unsuccessful (51). Zinc oxide can be used to neutralize acids released in cross-linking or curing. For example, in cross-linking chlorofluorocarbons with polyisocyanates, zinc oxide functions both as a catalyst to split out hydrogen chloride from the saturated chlorofluorocarbon and also as a reactant to neutralize the acid formed (42). Zinc oxide or carbonate serves a similar function in the cross-linking of fluorocarbons with polyphenols, polyformaldehyde, epoxy, or boron polymers by dicumyl peroxide (3). Zinc chloride and particularly zinc nitrate are frequently employed as acidic catalysts to cure or set various urea-formaldehyde crushproofing resins for textiles. Consumption is several million pounds a year. Zinc fluoborate is similarly used for epoxy textile resins (49, 64, 84, 94, 779, 130, 762, 176, 177, 790) and for other epoxy compositions (71, 27, 733). Other zinc compounds proposed for curing epoxies include zinc chloride plus boron trifluoride ( 3 4 ,chelates of zinc chloride with phenols ( 7 4 , and chelates of zinc bromide (79, 772), benzoate, or stearate (198) with organic amines. These

Organozinc additives reduce static, kill organisms, improve dyeability complex catalysts cure epoxies only above 60' C. so that the resins can be mixed and stored safely at room temperature. Other zinc compounds reported as accelerators or curing and cross-linking agents are shown in Table VI. Other Additive Uses

Antistatic Agents. Zinc soaps, often in combination with other chemicals, are used a t 1 p.h.r. or less to reduce the surface friction of plastics and thus prevent the buildup of static electricity. For example, a mixture of zinc stearate and polyethylene glycol monoesters at about 4 p.h.r. makes polystyrene nondusting (749). Zinc caproate, caprylate, or pelargonate with such tertiary amines as triisopropanol amine act as antistatic agents for polystyrene, polyvinylidene chloride, methacrylates, and acrylonitrile-styrene and butadiene-styrene copolymers (36). Zinc stearate alone may be used to prevent accumulation of static electricity in flame-spraying polyethylene, polyisobutylene, or acrylates ( 75). Zinc salts also contribute antistatic properties by providing charged particles to remove electricity by conduction. The N-methyl-N-stearyl dithiocarbamate has recently been patented as an antistatic agent (75). Composite plastic films containing a surface layer of an olefin-

TABLE IV.

SOME POLYOLEFIN STABILIZERS CONTAINING ZINC

vinylidene chloride copolymer over Mylar or various thermoplastic films can be given an antistatic treatment by spraying or dip-sizing with a dilute solution of zinc chloride, sodium chloride, and sodium lauryl sulfate (I58).

Fungistats a n d Bacteriostats. Zinc chemicals are effective agents for protection against fungi and other microorganisms. Use of 3 to 8 p.h.r. of mixed calciumzinc salts as stabilizers for vinyl-asbestos floor tile also gives protection against molds and other fungi (759). In PVC for outdoor use barium-cadmium-zinc stabilizers act as supplemental fungistats to trichloromethylmercapto compounds (708). Plastic sheets can be dipped into solutions of zinc salts for protection against microorganisms (725). Zinc is often the preferred metal for incorporation into organic compounds or metal alloys for control of microorganisms in plastics. Some recently patented examples are zinc salicylanilide (724); zinc pentachlorophenolate (67) ; zinc phenolate, naphtholate, dibromophenolate, and ethyl mercurithiosalicylate (707); and metallic zinc or aluminum-zinc alloys in combination with copper or a noble metal (700). Flameproofing. Zinc oxide is sometimes used as a minor component in fireproofing compounds for polyethylene (l76)or particularly for textiles (28).

TABLE V. TYPICAL FORMULATION FOR EPOXY ADHESIVE CONTAINING ZINC DUSTa ~~

Components,

Resin

70

Zinc oxide Colloidal sulfur

0.5 0.1

Polyethylene

Zinc oxide Nonylphenyl phosphite

1.o 1.0

Polyethylene

Zinc stearate Magnesium stearate Triisooctyl phosphite 2,6-Di-tert-butyl-4-methylphenol

0.8 0.8 2.0 5.0

Polyethylene

Zinc monolaurylmaleate 0.1-0.2 or succinate Calcium monoethylhexyl 0.1-0.3 adipate or monolauryl maleate N-stearoyl-p-aminophenol 0.04-0.05 or other antioxidant Zinc salt of phenolic condensation products

0.002-5.0

Zinc diethyl phenyl-2naphthylamine

...

+

Zinc oxide or sulfide Organic sulfur or phosphorus compounds Zinc oxide or soap Ultraviolet absorber

1 .o

Polyethylene Polypropylene

...

Polyolefins

Polypropylene

100 parts 14 25 50 80 100

TABLE VI. SOME ZINC COMPOUNDS USED AS ACCELERATORS OR CURING AGENTS

Chloride

Polypropylene

~

Amount

Epoxy resin Mica Short-fiber asbestos Alumina Talc Zinc dust

Zinc Compound

Polyolefins

5.0

Component

Mercaptide Naphthenate Octoate Soaps Soaps and naphthenates Stearate Sulfate

Resin

Reference

Poly(viny1 alcohol) Vinyl ethers Polyurethane elastomers Polyurethane elastomers EPOXY EPOXY Poly(viny1 chloride) Silicone emulsions Acrylics Melamine

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Water Repellency. Zinc stearate and other metal soaps can be added at 1 to 30 p.h.r. to ethylene-propylene and other alpha-olefin copolymers to improve water repellency and insulating properties (143). Die Swell. A mixture of up to 95y0zinc pentachlorothiophenol and iron phthalocyanine added to polyethylene at up to 5 p.h.r. reduces die swell on extrusion ( 7 23). Synthetic Fibers. The low affinity of many fibers for dyes can be increased by treatment with salts of zinc, magnesium, and aluminum which have colorless ions and do not cause deterioration of the fiber. Some of the zinc salts recommended are listed in Table VII. Generally the metal compound is added to the melt before drawing and spinning in amounts of 1 to 10%. Acrylic filaments can be treated by passage through an aqueous bath containing 0.02 to 0.8y0zinc oxide (792) or 2 to 4% zinc sulfate (795). Polyolefin fibers can be treated similarly with zinc octoate, other soaps, or organic coordination compounds (70). Surface treatment of polyamide fibers with solutions of zinc chloride is claimed to iniprove snag resistance (773), friction, moisture pickup, dimensional stability, antistatic properties (72), and abrasion resistance (763) and to impart a dull luster comparable to that obtained with titanium dioxide. Treatment of nylon with zinc acetate and gallic acid or pyrogallol improves its adhesion to synthetic rubber (96). Incorporation of 0.05 to 0.2% zinc (as sodium zincate) in viscose rayon improves crimpability of the fiber (38). Incorporation of 2y0 zinc sulfate or other compounds in

the polymer (755) or spinning bath (783) retards the discoloration of PVC fibers. Zinc-Base Polymers

Polymers containing zinc and other metals have been the subject of considerable research in recent years, particularly in view of their potentially high thermal and chemical stability. Most of these polymers also contain benzene rings or other aromatic groups of high stability. For example, high-melting, glassy polymers containing 18Y0 zinc by weight can be made by polymerizing zinc cinnamate with peroxide or other free radical catalysts. The polymer melts at 205’ C. I t is soluble in such

Bisphenyl phosphinate (21)

L---l

H

Bisimidazole (23) Dithioxamide (154)

2,d-Dihydroxy-pbenzoquinone (154)

NH

NH ll

/I

TABLE V I I S SOME ZINC SALTS USED TO INCREASE FIBER DYEABILITY

Fiber Polypropylene

Polyethylene Polyester Polyacetal A cry 1ic

Zinc Salt Stearate Oxide or hydroxide Organic complexes Stearate Stearate Monomethyl adipate Dimethyl trimesate Stearate Oxide

Reference

(55, 85,86, 134, 736, 769) (55, 85)

Naphthazarin thiosemicarbazone (32)

(85)

/

Bis(Z-pyridinyl)biphenylene-4-4’-diimine (57)

TABLE V I I I . SOME ZINC-CONTAINING POLYMERS STU D I ED FOR H I G H -TEMPE RATURE PROPER T I ES

Organic Monomer

]

RejeTence

Bis(2-pyridinyl)biphenylene-4,4’-diimine Tetraacetylethane 2,5-Dihydroxy-p-benzoquinone Dithioxamide p-Phthaloylbis( acetylethyl acetate) Bisdithiocarbamic acid and derivatives Thiamides plus a-picoline or 2,6-lutidine Methacrylhydrazide

p-( 1,3-Butanedione)-N-phenylglycine 34

INDUSTRIAL A N D ENGINEERING CHEMISTRY

n

6-9

p=i: ICH ’ *zn’ , J CH I

T i

C

/ \

YH2 ?

-N---Zn--.N11H H 1 \ 0, ,CH2

\ /

/ \ c-o o-c

1 1 0 \ /

C

II

0 #-(1,3-Butanedione)-N-phenylglycine (122)

Figure 2. Polymers with zinc in the backbone have high resistance to thermal degradation. Some are coordination comfiounds in which the zinc is held in chelate form, as the ones shown here

highly polar solvents as chlorinated polyphenyls and dimethyl sulfoxide (56). Similarly, zinc can be incorporated into polyester resins to form the group -COOZnOCO--. Zinc can be introduced into such resins by adding zinc acetate to the resin batch during the cook-for example, to a partially reacted mixture of ethylene glycol and dimethyl terephthalate. Incorporation of zinc into the resin improves the wetting of metal surfaces, increases its toughness and resistance to thermal shock, and enhances its thermal stability. Zinc-bearing resins of this type have been proposed as wire enamels (5). Somewhat similar results are obtained with polyamides (50). A number of more exotic structures have also been studied, chiefly coordination compounds in which the zinc is held in chelate form. Examples are low polymers of the type [Zn(OPPhzO)z], and [Zn(OPPhCH80)2],, where Ph is the phenyl group. These polymers are believed to have the structures shown in Figure 2. On heating, the zinc bisphenyl phosphinate polymers do not begin to lose weight until 495’ C., and the zinc phenyl methyl phosphinate polymers begin at 41 5 C. (27) *

Several chelate structures give high thermal stability. For example, polyzincbisimidazole is stable to 500’ to 575 O C. in nitrogen (23); polyzincbis(8-hydroxy-5quino1yl)methane to 500’ C. (82); and polyzincnaphthazarin thiosemicarbazone to 450’ C. (32). Some other zinc-containing polymers studied for high temperature properties are listed in Table VIII. Structures of selected coordination polymers are shown in Figure 2. Other zinc-containing polymers are the luminescent zinc-chdated anils of 5,5’-niethylenebissalicylanilide (752) and products made from zinc ammine chloride (766) and organozinc salts of boronic acids (704). Outlook

As plastics are subjected to an ever-widening range of environmental conditions, use of zinc chemicals and other additives is certain to increase. Many applications are already well established. Others, like the use of zinc oxide as an ultraviolet stabilizer, are still being investigated. Particularly promising for the future is the investigation for polymer use of the large number of new organozinc compounds now being synthesized in this country and abroad. REFERENCES (1) Ackerman B (to Deutsche Advance Production G.m.b.H.), Belgian Patent 612,218 (Juiy 1962). (2) Advance Division, Carlisle Chemical Works, “Modern Vinyl Compounding and Stabilization,” New Brunswick, N. J., 1965. (3) Alekseenko, V. I., et ol., Russian Patent 150,959 (Oct. 25, 1962); C.A. 58,10373 (1963). (4) Aluminium FranSais, British Patent 791,653 (March 5, 1958).

i,

(5) Arndt, R. P. (to Anaconda Wire & Cable Co.), U. S. Patent 2,985,624 (May 23, 1961). (6) Arnold, R. G., Kehr, C. L., Verbanc, J. J. (to E. I. du Pont de Nemours & Co.), Ibid., 2,846,416 (Aug. 5, 1958). (7) Ascher R (to Middlesex Oil and Chemical Works, Ltd.), British Patent 794,107 ? A p h 30, 1958). (8) Aubrey, D. W. (to Adhesive Tapes, Ltd.), Ibid., 952,590 (March 18, 1964). (9) Azienda Colori Nazionali Affini A.C.N.A., Zbid., 896,327 (May 16, 1962). (10) Barker, P. W., Mills, W. P., Morris, W. (Imperial Chemical Industries, Ltd.), Zbid., 953,757 (April 2, 1964). (11) Bataafsche Petroleum Maatschappij, Dutch Patent 86,579 (Oct. 15, 1957). (12) Baum, B. 0. (to Union Carbide Corp.), U. S. Patent 3,041,311 (June 26, 1962).

(13) Baum, B., Perun, A. L., SPE Tmm. 2, 250 (1962). (14) Bawn, C. V. (to United States Rubber Co.), Belgian Patent 636,312 (Dec. 16, 1963). (15) Beike, H., Zorn, E., Erberich, G., German Patent 883,500 (July 20, 1953). (16) Bemberg A. G., J.P., British Patent 911,108 (Nov. 21, 1962). (17) Bentov, I., Mod. Plastics 40, 138 (October 1962). (IS) Bishop, R. B., Ibid., 33, 141 (October 1955). (19) Bishop, R. R. (to Leicester Lovell & Co., Ltd.), British Patent 836,695 (June 9, 1960). (20) Blatz, P. S. (to E. I. d u Pont de Nemours & Co.), German Patent 1,133,144 (July 19, 1962). (21) Block, B. P., Rose, S. H., Schumann, C. W., Roth, E. S., Simkin, J., J. Am. Chem. Soc. 84, 3200 (1962). (22) Bonnard, L. (to Societe Rhodiaceta), French Patent 1,352,243 (Feb. 14, 1964). (23) Brown, G. P., Aftergut, S., J.PolymerSci. Pt. A 2 (4), 1839 (1964). (24) Brown, H. E., “Zinc Oxide Rediscovered,” pp. 90-1, New Jersey Zinc Co., New York, 1958. (25) Brown, H. P., Rubber Chem. Technol. 36 (4), 931 (1963). (26) Brown, H. P., Carlson, E. J. (to B. F. Goodrich Co.), German Patent 944,397 (1956). (27) Brueschweiler, H., Zuppinger, P. (to Ciba, Ltd.), U. S. Patent 3,004,931 (Oct. 17, 1961). (28) Buck G. S. in “Encyclopedia of Chemical Technolog ” R. E. Kirk and D. F. Othmer: eds., vol. 6 , p. 551, Interscience, New York, 1957: (29) Calao, J. J., Gurvitch, M . M., Plastics Technol. 5, 36 (March 1959). (30) Canarios, C. M., Weir, V. J., Lerner, R. W. (to Ferro Corp.), U. S. Patent 3,030,334 (April 17, 1962). (31) Carlisle Chemical Works, Inc., British Patent 942,104 (Nov. 20, 1963). (32) Chakravarty, D. N., Drinkard, W. C., J.Indian Chem. Sac. 37,517 (1960). (33) Charles, R . G., J. Polymer Sci. Pt. A 1, 267 (1963). (34) Chenicek A G Alster, F. G. (to Martin-Marietta Corp.), U. S. Patent 3,080,341 (Ma(rch’5, 7963). (35) Chwassus F., Broutelles R., Jacque L., “The Stabilization of Polyvinyl Chloride,” S;. Martin’s Pres;, Inc., New qork, 1963. (36) Coler, M. A., Cutler, J. A., Louis, A. S.,U. S. Patent 2,992,199 (July 11, 1961). (37) Cooper, W. (to Dunlop Rubber Co., Ltd.), British Patent 831,061 (March 23, 1960). (38) Courtaulds, Ltd., Belgian Patent 620,593 (Nov. 14, 1962). (39) Csendes, E , (to E. I. d u Pont de Ncmours & Co.), U. S. Patent 2,870,157 (Jan. 20, 1959). (40) Darby, R., SPE Tech. Pupers 10, Session I X , Paper No, 3 (1964). (41) Darcy, G. J., Plustics Techno/. 7, 39 (November 1961). (42) Davis, H. R., Honn, F. J., Griffis, C. B., Montermoso, J. C. (to Minnesota Mining & Mfg. Co.), U. S. Patent 3,071,565 (Jan.1, 1963). (43) Deligny J Zagdoun R. (to Pechiney-Comp. de Produits Chim. et Electrometall.), Fkn‘dh Patent 11205,729 (Feb. 4, 1960). (44) Dodgson, D. P., J . Oil Colour Chemists Assoc. 43, 576 (1960). (45) Dow Chemical Co., British Patent 807,455 (Jan. 14, 1959). (46) E. I. d u Pont de Nemours & Co., Zbid., 894,701 (April 26, 1962). (47) Elliott, S. B. (to Ferro Chemical Corp.), U. S. Patent 2,861,052 (Nov. 18, 1958). (48) Zbid., 2,918,451 (Dec. 22, 1959). (49) Enders, H., Zoerkendoerfer, R., Pusch, G. (to Chemische Fabrik Pfersec), German Patent 1,122,036 (Jan. 18, 1962). (50) Endrey A L. Angelo R. J. (to E. I. d u Pont de Nemours & Co.), British Patent 945),674 $an. 8, 1664). (51) Feild, G. B. (to Hercules Powder Co.), U. S. Patent 3,017,379 (Jan. 16, 1962). (52) Ferrigno, T. H., “Rigid Plastics Foams,” p. 227, Reinhold, New York, 1963. (53) Ferro Corp., British Patent 905,074 (Sept. 5, 1962). (54) Fielden, R. J., Dadson, L. M. (to Imperial Chemical Industries, Ltd.), Ibid., 961,457 (June 24, 1964). (55) Fior, A. Caldo C. (to Montecatini SOC. Gen. per 1’Industria Mineraria e Chimica), 6elgian Patent 614,776 (Sept. 7, 1962). (56) Freedman M. L. Elliott, S. B. (to Ferro Chemical Corp.), U. S. Patent 3,024,222 (March 6, i962). (57) Friihauf, E. J., Bailar, J. C., J . Inorg. Nud. Chem. 24, 1205 (1962). (58) Frye, A. H., Horst, R. W., J . PolymerSci. 40, 419 (1959). (59) Zbid., 45, 1 (1960). (60) Fuchsman, C. H., SPE Tech. Papers 7, Session 5, No. 1 (1961). (61) Genth, H. (to Farbenfabriken Bayer, A.G.), German Patent 1,084,912 (JulyJ, 1960). (62) Godfrey, G. J., Sheftel, M. S., Mod. Pluslics Encycl. 1961, p. 423. (63) Gould, D. F., “Phenolic Resins,” p. 62, Reinhold, New York, 1959. (64) Guest, H. R., Adams, J. T., Sookne, A. M., Phillips, B., Frostick, F. C. (to Union Carbide Corp.), German Patent 1,146,028 (March 28, 1963). (65) Hackert, H. A., Ktmststofe 52, 624 (1962). (66) Hansen, F. R. (to Ferro Chemical Corp.), British Patent 811,532 (April 8, 1959). (67) Hansen, F. R., Elliott, S. G. (to Ferro Corp.), German Patent 1,163,536 (Feb. 20, 1964). (68) Hansen, J. E. (to E. I. du Pont de Nemours & Co.), U. S. Patent 3,009,900 (Nov. 21, 1961). (69) Hanusch, F. (to Badische Anilin & Soda Fabrik), German Patent 940,609 (March 22, 1956). (70) Haward, R. N., Boultbee, T. H. (to Shell Oil Co.), U. S. Patent 2,994,675 (Aug. 1, 1961). (71) Hecker, A. C., Pollock, M. W., Cohen, S. (to Argus Chemical Corp.), British Patent 903,933 (Aug. 22, 1962); German Patent 1,150,202 (June 12, 1963). (72) Herschler, R. J. (to Crown Zellerbach Corp.), U. S. Patent 3,023,074 (Feb. 27, 1962). (73) Heuck, C., Stark, E., Doppler, W. (to Farbewerke Hoechst), German Patent 1,096,598 (Jan. 5, 1961). (74) High Polymer Chemical Industries, Ltd., French Patent 1,351,508 (Feb. 7, 1964). (75) Hoechst A. G., Farbewerke, Belgian Patent 611,660 (June 18, 1962).

VOL. 5 8

NO. 5 M A Y 1 9 6 6

35

(76) Hoesch, Chemische Fabrik, Zbid.,611,161 (Dec. 29, 1961). (77) Ibid., 630,201 (July 15, 1963). (78) Hohenberg, P. hl., James, W.R., Wechsberg, H . E. (to Monsanto Chemical Co.), U. S. Patent 3,017,371 (Jan. 16, 1962). (79) Holmes, R. R., Jenkins, L. T. (to Chemstrand Corp.), Zbid., 2,878,203 and 2,878,206 (March 17, 1959). (80) Zbid., 2,878,214 (March 17, 1959). (81) Honn, F. J. (to Minnesota Mining & Mfg. Co.), Zbid., 2,985,620 (hlay 23, 1961). (82) Horowitz, E., Perros, T. P., J . I n o r f . Nucl. Chem. 26 ( I ) , 139 (1964). (83) Hoyt Metal Co. of Great Britian, Ltd., British Patent 851,974 (Oct. 19, 1960). (84) Hurwitz, M., Wang, S. Y. (to Rohm & Haas C o . ) , U. S. Patent 3,097,050 (July 9, 1963). (85) Imperial Chemical Industries, Ltd., Belgian Patent 614,566 (Sept. 3, 1962). (86) Zbid.,619,493 (Dec. 28, 1962). (87) Zbid., 620,927 (Jan. 31, 1963). (88) Jasching, W., XuntlJfofe 52, 458 (1962). (89) Jellinek, H . H . G., “Degradation of Vinyl Polymers,” Academic Press, New York, 1955. (90) Jenkins, L. T., Campbell, C . H . (to Chemstrand Corp.), U. S. Patent 2,850,472 (Sept. 2, 1958). (91) Jenkins, L. T., Holmes, R . R. (to Chemstrand Corp.), Ibid., 2,849,413 (Aug. 26, 1958). (92) Zbid., 2,878,213 (hlarch 17, 1959). (93) Jibhen, B. P. (to N. V. Onderzoekingsinsrituut Research), Dutch Patent 98,323 (June 15, 1961). (94) Jones: E. I$’.> Rayburn, J. A . , J.Appl. PolJmer Sci. 5,714 (1961). (95) Jordan, H . F., Smith, W.V. (to U. S. Rubber Co.), U. S. Patent 2,952,595 (Sept. 13, 1960). (96) Kanis, F., Bigga, H., East German Patent 21,645 (Aug. 4, 1961); C.A. 57, 1117 (1962). (97) Kauder, 0. S., Perry, N. L. (to Argus Chemical Corp.), U . S. Patent 3,003,998 (Oct. 10, 1961). (98) Zbid., 3,003,999. (99) Ibid.,3,004,000. (100) Kirmser, W., Rauen, H. M. (to Vereinigte Deutsche Metallwerke A.G.), German Patent 925,494 (March 24, 1955). (101) Klemchuk, P. (to J. R. Geigy A.G.), Belgian Patent 633,440 (Dec. 10, 1963). (102) Zbid.,633,441. (103) Kopetz, K.. IV‘lck, G., Hahmann, 0. (to Chemische Werke Huels A.G.), German Patent 1,138,215 (Oct. 18, 1962). (104) Korshak, V . V., e t nl., Vymkomolektil. Soedin. 4 , 188 (1962); C.A. 56, 15663 (1962). (105) Zbid., 5, 1288 (1963); C.A. 59, 15392 (1963). (106) Kryszewski, M., Skorko, M., J . PolymerSci. Pt. C 4 , 1401 (1964). (107) Lal, J. (to H . D. Justi & Sons, Inc.), U. S. Patent 2,873,263 (Feb. 10, 1959). (108) Lanfield, H., Taylor, W. S., Plariics Terhnol. 8, 29 (August 1962). (109) Lasman, H. R., M o d . Plo5llc5 E n c y l . 1963, p. 422; 1964, p. 364. (110) Lasman, H . R . , S P E J . 18,1184 (1962). (111) Lee H. Iieville, K., “Epoxy Resins,” (a) p. 220, (b) p. 226, ( c ) p. 2439 McGra;v-Hiil, New York, 1957. (112) Leicester, Love11 & Co., Ltd., French Patent 1,351,709 (Feb. 7, 1964). (113) Lord, F. W. (to Imperial Chemical Industries Ltd.), British Patent 876,058 (Aug. 30, 1961). (114) Mack, G. P., M o d . Plastics Encyd. 1960, p. 333. (115) Zbid., 1962, p. 466. (116) Ibtd., 1963, p. 479. (117) Zbid., 1964, p. 405. (118) Ibid., 1965, p. 382. (119) hlaeder, A , , Aenishaenslin, R. (to Ciba, Ltd.), Swiss Patent 364,482 (Nov. 15, 1962). (120) hlakowski, H . S., Cain, W’. P., Wei, P. E,, IND.EKG.CHEH.PROD. RES. 3, 282 (1964). DEVELOP. (121) Manzella, A. S., Hyre, J. E., Blue, D . C. (to Union Carbide Corp.), Belgian Patient 632,091 (Sept. 2, 1963). (122) Mattison, L. E., Phipps, M. S., Kazan, J., Alfred, L., J . Polymer Sci. 54, 117 (1961). (123; McGlamery, R . M . (to Phillips Petroleum Co.), U . S. Patent 3,157,612 f\ov. 17. 1964). (124) hlelnikov, N.N., e! a i . , Russian Patent 126,259 (Feb. IO, 1960). (125) Mendelsnhn, M., Horowitz, C. (Yardney International Corp.), U. S. Patent 3,079,213 (Feb. 26, 1963). (126) Monsanto Chemical Co., British Patent 849,181 (Sept. 21, 1960). (127) Ibid.,876,443 (Aug. 30, 1961). 1128) . , Zbid.. 940,028 (Oct. 23, 1963). (129) Nakazawa, T. (to Kiss0 Chemical Industries, Ltd.), Japanese Patent 1215 (Fcb. 19, 1963). (130) Narita, S. (to Kureha Spinning Co.): Japanese qatents 941 and 946 (Feb. 3, 1964). .. . (131) Nass, L. I., h d . Plastics 40, 127 (April 1963). (132) Zbid., p. 151 (March 1963). (133) Xewey, H . A . (to Shell Development Co.), U. S. Patent 2,795,565 (June 11, 1957). (134) Nishio, M., Shin, Y., Urata, Y . (toToyo Rayon Co.), Japanese Patent 20,489 (Oct. 4, 1963). (I 35) Onderzoekingsinstituut Research N. V., British Patent 938,702 (Oct. 2, 1963). (136) O’Neill, !\’, A., et ai. (to Imperial Chemical Industries), British Patent 954.387 (Aoril . . 8.. 1964). (137) Penn, W. S., “PVCTechnology,” Chaps. 11 and 12, Maclaren, London, 1962. (138) Penn, W.S., Rubber Plastics Weekly 141 (No. 1-6), 8, 42, 80, 122, 152, 206 (1961). (139) Perry, M., Bruins, P. F., Plastics Technol. 1, 609 (November 1955). (140) Zbid., p. 673 (December 1955). (141) Perry, N. L., .Ilood. Plastics Eni)lrl. 1963, p. 502. (142) Perry, N. L., Pollock, M. W. (to Argus Chemical Co.), Belgian Patent 635,264 (Jan. 22, 1964). \

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INDUSTRIAL A N D ENGINEERING CHEMISTRY

(143) Pirelli SOC.per Azioni and Montecatini SOC.Gen., Italian Patent 613,494 (Dec. 6, 1960). (144) Pollock, M. W. (to Argus Chemical Co.), Belgian Patent 635,830 (Feb. 5, (1 964). (145) Polyplastic S.A., French Patent 1,255,077 (Jan. 23, 1961). (146) Porck, A. J. (to E. I. dn Pont de Nemours & Co.), Belgian Patent 609,474 (April 24, 1962). (147) Porter, M. R. (to Midland Silicones, Ltd.), British Patent 930,470 (July 3, 1963). (148) Powers P. O., in “Encvclopedia of Chemical Technology ” R. E. Kirk and D . F. OthLer, eds., Vol. 1, p. 757, Interscience, New York, 1947. (149) Price, R . M . (to Dow Chemical (20.1, L’. S. Patent 2,965,589 (Dec. 20, 1960). (150) Rhodiaceta, SOC.,French Patent 1,328,940 (June 7, 1963). (151) Riser, G. R., Hunter, J. I.,Ard, J. S., Witnauer: L. P., S P E J . 19, 729 (1963). (152) Rode, V. V., et nl., Vysokornolekul. Soedin. 4 , 13 (1962); C . A . 57, 1055 (1962). (153) Roos E. Freyrag H . Kallert, W. (to Farbenfabriken Bayer A.G.), German Patent l,i60:171 (Dei. 2 j , 1963). (154) Rose, S. H., Block, B. P., Davis, J . E., Inorg. Chem. 3, 1258 (1964). (155) Rosner, T., et al.: Polimery 8, (7-8), 291 (1963). (156) Ibid., 9 (I), 7 (1964). (157) Ryshavy, D., Balaban, L., SPE T m n r . 2, 25 (1962). (158) Sapper, D. I. (to E. I. du Pont de Piemours & Co.), U. S. Patent 2,925,356 (Feb. 16, 1960). (159) Savarese, F. B., M o d . Plastics Encycl. 1961, p. 397. (160) Schildknecht, C. E., “Polymer Processes,” p. 744, Interscience, New York, 1956. (161) Schlenker, F. (to Chemische Werke Albert), U. S. Patent 2,803,609 (Aug. 20, 1957). (162) Schroeder, C. ’A’. (to Shell Oil Co.), Zbid., 3,018,262 (Jan. 23, 1962). (163) Schuller, E., Jaensch, M., Fuserforsch. Texliiterh. 14, 97 (1963). (164) Seefluth, C. L. (to Phillips Perroleum Co.), U. S. Patent 2,981,979 (May 2, 1961). (165) Shimizu, A. (to Bureau of Industrial Technics), Japaucsc Patent 889 (Feb. 21, 1959). (166) Simkin, J., Block, B. P., U. S. Dept. of Com., Office Tech. Serv., P. B. Rept. 148,132 (1962). (167) Simonds. H. R., Church, J. h?., “A Concise Guide to Plastics,” p. 156, Reinhold, New York, 1963. (168) Simonds, H. R., Weith A . J. Bigelow M. H . “Handbook of Plastics,” (a) p. 396, (b) p. 304, (c) p. i14, Vah Nosrranh, Prince‘ton, N. J., 1949. (169) Simpson, H. V.; Erlich, V. L. (to Reeves Brorhers, Inc.), Brlgian Patent 617,280 (Nov. 5, 1962). (170) Simpson, J . E., M o d . Plastics 40, 107 (May 1963). (171) Smith, H. V., Brit. Plastics 25, 304 (1952). (172) Zbid.,27, 176 (1954). (173) Smith, R. D . (to American Enka Corp.), U. S. Patent 3,060,550 (Oct. 30, 1962). (174) Solomon, S,l. hi. (to General Electric Co.), Ibid.,3,098,833 (July 23, 1963). (175) Solvay & Cie, Belgian Patrnr 549,463 (July 31, 1956). (176) Sookne 4.>I. Galligan J. D. Guesr H. R. Adams, J. T . (to Cnion Carbide Corp.), U. k: Pateht 3,024,135 (March 6,’1962).’ (177) Sookne, A. SI.,Guest, H . R., Adams, J. T. (to Union Carbide Corp.), Zbid., 3,026,216 (March 20, 1962). (178) Sorenson 14’. R. Campbell, T. W., “Preparative Eiiethods of Polymer Chemistry,” 300, 363, Interscience, Piew York, 1961. (179) Stastnv F. (to Badische Anilin & Soda Fabrik), German Patent 870,331 (March 12,’1953). (180) Stepek, J., Franta, I., Dolezel, B., M o d . Plashis 40, 145 (August 1963). (181) Struthers, J. A. Boyer R . F. Goggin W. C. in “Encyclopedia of Chemical Technology,” R. E.’Kirk and D.’F. OthAer, eds:, Vol. 13, p. 158, Interscience, New York, 1954. (182) Stutz, G. F., J . Franklin Znsl. 202, 89 (1926). (183) Tanaka, H., et ~ i .(to Daiwa Spinning Co., Ltd.), Japanese Patent 1475 (hlay 8, 1962). (184) Tarkington, T. W., Whitt, C. D. (to hlonsanro Chemical Co.), V. S. Patent 3,088,932 (May 7, 1963). (185) Terentev, A. P., el al., Vjsokomoiekul. Soedin. 4, 821, 1005 (1962); C.A. 59, 772 (1963). (186) Zbid.: 6 , 1267 (1964); C..4. 61, 14794 (1964). (187) Thomson-Houston, Compagnie FranSaise, French Patent 1,320,189 (March 8, 1963). (188) Tolmachev, V. N., e t ai., Vysokomolekul. Soedin. 5, 512 (1963); C.4. 59, 2966 (1963). (189) Tsunoda, T., Yamaoka, T., J. A,6pl. PolymerSci. 8 , 1379 (1964). (190) Tullio, V. (to E. I. du Pont de Nemours & Co.), U. S. Patent 3,044,843 (July 17, 1962). (191) Varenelli, A. D., W i r e Wire Prod. 36, 861 (1961). (192) Veitch, J. D. (to Monsanto Chemical Co.), U. S. Patent 3,061,398 (Oct. 30, 1962). (193) Waeser, B., KunsLrtofe 48, 320 (1958). (194) Wallace & Tiernan, Inc., LucidolDiv., Prod, Bull. 9, 101, June 1963. (195) Webb M. Q. (to E. I. d u Pont de Nemours 8; Co.), U. S. Patent 3,123,432 (March 3,’1964). (196) Werner, 4.C., .Mod. P / Q i t i C S 39, 135 (October 1961). (197) rVeyer, D. E. (to Dow Corning Corp.), U. S. Patent 3,108,985 (Oct. 29, 1963). (198) Wille H . Jellinek K. (to Gesellschaft fuer Teerverwertung G.m.b.H.), German i a t e d t 1,097,l;Z (Jan. 12, 1961). (199) \Vinding, C, C., Hiatt, G. D., “Polymeric Materials,” pp. 230, 236, h1cGrawHill, Piew York, 1961, (200) Wright, B., Williamson, G. R. (to Shell Internationale Research), British Patent 937,630 (Sept. 25, 1963). (201) Wright, G . C., Hunsberger, J. (to General Aniline & Film Corp.), U. S. Patent 3,000,869 (Sepr. 19, 1961). (202) Zaremsky, B. (to Ferro Corp.), Ibid.,3,067,166 (Dec. 4, 1962). (203) Zurakowska-Orszagh J. Sobolewska, Z . E., Polish Acad. Sci., Inst. Nucl. Res. Rept. Ah.31l/xvii, ;96i.

b.