Document 377G6QJrDQkYL5aLxaQkBXzeD

PVC Industry and Stabilisers --A Discussion From The Environmental Point of View- R&S 131103 Eiichi Morozumi* T. y.f2~>--L.' .* \ 1 -V /tKj 3 * rV-_ I. Foreword This artidf'will deal with the changing PVC and stabilizer industry from the viewpoints of environmental protection, - safety and hygiene. Japan's PVC industry has developed as the mainstay of the petrochemical industry, laying foundations for the na tion's plastics industry. In the early stage of the 1945-55 period PVC production was put on a commercial basis. Products processed from PVC then on sale at department stores were called "nylon." In the United States nylon resin was being used as raw material for popular products ^mch as stockings. /a. mdustry. __thougkJieaet. with - many. _ occupies a; leading p.oitfctoa^ inr^yerl^marheS^'^ '- Looking. back on the tortuous path which" 'the^madstrjr'jiSSv^ treated in.-the. past I cannot. but fekLeb thousand,.emolions.-i-. - ' -Perhaps nobody could have thought that~the-.industry- would--- show such spectacular growth. The world's PVC production' jy^tinMted^.S," mil metric tons annually. The following reasons can be given for the remarkable rise in PVC production. - (1) PVC is relatively low in price.' Japan's production; now running at an annual rate of 1,200,000 metric tons, (about half the total output in Western Europe), owes much t<f the country's traditional and excellent basic technology in electric power generation as well as in carbide-acetylene processes. (2) Colorful combinations of stabilizers and lubricants were produced by new technologies. A wide range of appli cations were developed, including both rigid and flexible products. Full use was made of plasticizers in the field of flexible PVC. Moreover, the transparency of PVC lends itself to coloring in the processing of a variety of general-purpose products. All this helped create a unique market for PVC products. (3) Unique physical and chemical properties of this resin including weatherability made it possible not only to develop new variants of. PVC resin but also to com plete new fabrication techniques. An assortment of sophisticated fabricating equipment was developed to meet the diverse needs of users and customers. Thus the field of application widened to an extent matched by few other plastics. * Manager of Chemical Dept., Damippon Irik & Chemicals Inc. Director, Japan Interstab Ltd. . All this has led to development of an integrated system of PVC technology. Further innovations in this field are expected to lead the PVC industry to a stage where greater growth bn new dimensions can be assured. . Changing Economic Climate . *:*' "' ' . ^ ' ': Until a year ago the general prediction was that the- growth of the PVC industry would either level off or slow down. Nobody painted a rosy picture. A pall of gloom hung over the future of the industry because the Govern ment and its associated agencies established in 1971-72 one statute after another to prevent environmental pollution. J^.shapej3fjhiiig5JjLCflm^j^^e^ppafeflLmJh^aulunm,, environmental;pollution originating, from PCB , ^Sehted a'inajor"sbtd^^probigm:":ilTe occurrence' jaL disease-i(bonerdisease-caused by "cadmium) in areas ' along. the tributaries- of -Ihe--Jiutsw-rivers ur-Toyama Prefect hire also evoked strong public concern.' These and other hts`:prdmpted"the'Bterto"pass''eaviFdrimehfal:pro--- tection legislation in 1970. The parliamentary sitting then was referred to as the-"antipollution Diet'-'- :*?-- The Law Concerning Waste Disposal and Cleaning imposed especially severe restrictions on PVC resin and its prod ucts. Chlorine generated by the resin and residual heavy metals from stabilizers and colorants were among the fac tors that caused the most "undesirable" label to be put on PVC. Casualties in many fires were attributed to the toxic fumes rising from new building materials using PVC. Thus the public image of this resin as the "culprit" became strengthened. In fiscal 1972, however, the Government's policy of pro moting Prime Minister Kakuei Tanaka's plan for remodel ing the Japanese' archipelago and reflatlonary fiscal and monetary measures brought about an increase in public investments. At the same time; the excess liquidity that resulted partly from such expansive economic policy creat ed a boom in speculation. In such circumstances the PVC industry, like other major industries, enjoyed strong de mand. The market for such building materials as rigid pipe, rain troughs, sheet and electric wires and cables basked in a boom. Meanwhile, the environmental protection measures that have come into force during the past few years, combined with the decline in the economic power of the United States, dampened investment in productive facilities on a global scale. In Japan, where antipollution legislation is more stringent than in other developed countries, investments in 42 Chemical Economy A Engineering Review jinTWfop control fariltrie* hav expanded rapidly during the past few years'. In value terms such outlays account for over 10 per ceni of total icvesm-erss in-new plants and equipment New investments in productive facilities were considerably restricted or delayed. As a result,- produc tive activity slowed down, with demand gracuaily exceed ing supply. This, coupled with tight monetary policy of 1973, set ths- stage for widespread commodity shortages. At present the situation in the PVC industry remains, X $ fluid, and it is difficult to predict with any reasonable ac- \ curacy how the industry will develop. In view of the sub ject of this article, the discussion that follows will center on stabilizers with emphasis placed on environmental tection, safety to human health and hygiene. . 3. Moves Toward Stringent Environmental Control Commodity shortages became apparent in April and May The PVC industry in 1973, as has been described, was 1973 against a background of global supply shortfalls. The subjected to violent economic and social changes. Trends nationwide water shortage that occurred in July and August in this industry were affected especially by statutes design provided an impetus to this trend, creating shortages in a ed to prevent pollution, most notably restrictions on waste wide segment of industry. In the meantime, in April 1973, emissions and the Food Sanitation Act (Table 1). for instance, a series of accidents occurred at chemical plants, beginning at plants of Kureha Chemical and Chiba PVC. Then another blow--the coastal blockade by fisher men in protest against mercury poisoning- in April through June. This forced shutdowm of electrolytic caustic soda plants or a switch-over to a new- manufacturing process not TOTTig mercuryr- But the result of this was a major reduction in chlorine supplies, (1) Revision of Health and Welfare Ministry Directive No. 178 - - - - This directive was a major topic of discussion in the PVC industry in 1973. It was announced in a gazette dated June 22, 1973 and went into effect Jan. 1, -1974. This directive is designed to impose restrictions both on the raw materials for and on the solutes -of stabilizers. Restrictions in the former category are aimed at prohibiting, for all practical A series of accidents at petrochemical plants that began purposes, the use of cadmium, lead, dibutyl tin compounds, in July 1973- at an Idemitsu plant in Tokuyama dealt a and cresol phosphite ester. - - ----- --- +--ii-c heavy blow to the PVC" industry for a long period. The The ban on the use of these compounds caused great re resultant rise in the price of raw materials contributed to percussions within the industry because they would have cost inflation. In addition to shortages of chlorine and a direct effect on human health not only in cases where ethylene, U.S. restrictions on the exports of allow more they were used in packaging material for food containers than trebled the price of stearic add, an important auxil iary raw material Thus the plastics industry as a whole was hit hard by a serious shortage of raw materials. but also in other applications. - -:- There was another problem posed by Directive 178--the lack of accuracy in the analysis method used to determine . In October 1973 came yet another blow that proved to whether a given compound is subject to the predetermined be the heaviest of all. The export embargo imposed by value from the standpoint of food hygiene. For this rea Arab oil producing countries created an "oil crisis," plung- son, complaints were filed by many persons engaged both l 'ing'lhe- Jap^ese'-ihfbf^cfu'dMe^nfr economic .confusion.'^; .. jmlhel ptoduction^f -thfiSgJiosiPqH.nds and in research A " 'What developed ia^a-moBihs--&at--foUowPd-was Txaropant-c.i_xleyfiloprnetit.,_Ihe..common-problem was-that compliaMF^ " "price~inflation.' "In"January 1974,-however,.:there appeared; to the directive was impossible unless the testing method signs of an increase in oil supplies." This notwithstanding, . . was improved\in more specific'terms.__ in a growing mood of conservation, statutory restrictions The Health and Welfare Ministry, aware "of the ^urgency" ."`were: imposed on-the- industrial-coBsumpUoo--.of^oil-and--- . of-tbe_prohlem,-_calld. a- session of the ana]ysis_cpmmittee ~_ electric power. In March 1974 the prices of petroleum ' of'the 'Japan "Hygienic PVC"Association" (JHPA)~ to- review products were increased - by ;a wide margin to . absorb the ... the. method...,A? will be described in greater detail later huge cost rise from the higher price of oil. - --- ; - * in'this "article, the restrictions , pertaining to raw "'materials R&S 131104 Table-1 Laws and regulations- related to safety and hygiene concerning stabilizers and colorants nm hose designed to prevent possible Harmful :ects os humans resulting from Intake or incling of toxic substances. Limited to mrrol of substances. Limited to control : substances and their handling: no previ ous are made for emissions. ,, ood Sanitation Act (Health <& Welfare Ministry) Health & Welfare Mlnistrv Directive No. 173-341) Law for Control of Poisonous Material (Health & Welfare Ministry) Drugs, Cosmetics. & Medical Instruments Act. (Health & Welfare Ministry) Law for Control of Household Goods Containing Poisonous Substances (Health & Welfare Ministry) Law Concerning Labor Safety and Hygiene (Labor Ministry) Those designed to prevent environmental . pollution from affecting human health. (Control of emissions) Law on Waste Disposal & Cleaning (Health & Welfare Ministry) Clean Water Law (Environment Agency) Clean Air Act (Environment Agency) Foul Smell Control Act (Environment Agency) Agricultural Soil Pollution Control Law , (Environment Agency) . Those designed to protect man from disaster, fire, explosion and other hazards due to inadequacies in equipment and structures. Fire Services Act (Ministry of Home Affairs) Law Concerning Safety of Consumer Goods (Ministry of International Trade & Industry) Law Concerning Inspection and Meaufacrcre of Chemical Substances (Minis-- or International Trade i Industry) 43 v.," yfrri .separated from the directive immediately beiore it feeaf fato effect, in a gazette dated Dec. 27, 1973. This /separated portion oi the directive was revised in the new Directive No- 340 of the ministry. As far as No. 173 was concerned, the range of tolerances lenient from the beginning. As a result, restrictions ^Jkie use of lead and other raw materials were in effect watered down. From the viewpoint of persons on the job this problem has a similarity to the problem of implement ing the Muskie Act, which caused a stir in the automotive industry; At any rate, what transpired with respect to Directive No. 173 threw light not only on some of the eco nomic and technical problems facing the industries concern ed but also on the importance of making a correct analysis of both the present and future situations including the gen eral social conditions. The lesson is that new-problems might arise in the stage where given regulations must be observed, making full compliance to them impossible^- An other thing is that in the absence- of a fairly accurate pros pect a technical solution to a given problem might take an unduly long time.! There is also a possibility that.contradic- tions might develop in relation to other relevant laws- and . regulations- The presence of loopholes- could also- make effective operation impossible. ; f .u ; : (2) Chang td Low-toxicity or Nontoxic Formulations Application of. new pollution control statutes, notably Di rective No. 178, in 1973, prompted moves in the Japanese vinyl industry to agree on voluntary restrictions. In the PVC industry these moves gave an impetus to efforts to use nontoxic compounds. More specifically, the main thrust of research and development work on stabilizers was toward fire establishment of low-toxicity or nontoxic formulations, notably, those involving octyl tin compounds, calcium and me combinations, and compounds not containing organic _J^wrmeta25f"Tbe use of cadmium and lead was avoided,- S^moves gained-momentum quickly to ban their use' -altogetherr-Thus a-new direction was set in the FVC fab rication technology. -- / -- . 4. Restrictions on Heavy-metal Stabilizers (1) Directives No. 370 and No. 434 ."** * Standards for food additives were established in the Health and Welfare Ministiy Directive No. 370. which went into effect in December 1959. In Directive No. 434, which be came effective in October 1966, full-scale restrictions were imposed on plastics used as packaging material for food containers from the standpoints of safety and hygiene. (2) PL Standards (JHPA) " .. PVC producers, in response to these new regulations, took the initiative in setting up the JHPA in June 1957. With a view toward supplying food in safety-guaranted containers to end-consumers, the PVC industry drew up voluntary standards (PL standards) for all packaging materials with, the guidance of the Health and Welfare Ministry. These- standards were prepared on the basis of relevant data in the United States- (FDA), West Germany (BGA), Britain. (BPF), France (LF) and the Netherlands (NSV). Accord ing to the rule thus established, each producer is required to select raw materials from a list prepared on the basis of certificates of confirmation issued by JHPA. JHPA acti vities are becoming increasingly important. It is playing a leading role in this particular field*not only for the PVC' industry but also for other plastics industries. I (3) .Directives No. 173 and No. 340 '* - Directive No. 434 was divided to' make revisions which were announced in Directive No. 173. .The revision was an nounced in a gazette on June 22, 1973 and went into effect on Jan. 1, 1974.. The purpose of the new directive was to put the technical relationship between packaged food and packaging material in proper perspective and adapt a wide variety of materials more closely to reality. The ban on the use of cadmium, lead, dibutyl fin and phosphoric ester was certain to affect fields of application other than food packaging and containers. However, the restrictions calling for quality tests of raw materials were eased in Directive No. 340 dated Dec. 27, 1973, immediate ly before Directive. No. 178 went into effect. .The revision !- - * -V* -1* -- < ' . .-V 1 Table 2 Regulations m raw materials and dissolution in Health & Welfare Ministry .Directives No. 178 and No. 340 and PL standards " Food item . . Test solution- .Test-item Standard value (ppm) - - _ Extraction conditions Alcoholic beverages** 20% alcohol . "Water 4% acetic add . Others Evaporation residue Potassium per manganate consumption Heavy metals Materials test** Below 30 Below 10 ' .... "60*C, 30 minutes -"* As lead Below - 1 Cadmium . Below 100 Lead Below 100 Dibutyl tin 0 TCP Below 1,000 : tc - , -- -- Fats and oils & fatty foods** n-heptane Water 4% acetic add Others -Ffipds and beverages r than above two s 4% acetic add Water 4% acetic add Evaporation residue Potassium per manganate consumption Heavy metals Materials test** Below 150 Below 10 As lead Below ' 1 Cadmium Below 100 Lead Below 100 Dibutyltin Below 1,000 TCP Above 1,000 Evaporation residue Potassium perxaaaganate consumption Heavy metal* As lead Below 30 Below 10 Below 1 60*C, 30 minutes 60*C, 30 minutes * Same u dissolution regulation is Health & Welfare Ministry Directive No. 178 * Same es material regulation in Health & Welfare Ministry Directive No. 178 44 Chemical Econ my 8* Engineering Review '*v9s< -9.>-*A concerning the handling of PVC apparatus made it man* datory to make only solute tesa for product other than those used for eating and crmking purposes., and kitchen utensils. In other words, pipes, troughs, wires and cables, and sheet, for example, were exempted from quality tests. Thus the ban on the use of cadmium and lead was virtual ly lifted- _ .................................... Inadequacies in the analysis method prescribed by Direc tive No. 178 were corrected in bulletin No. 5551 issued by JHPA. The testing method pertaining to dibutyl tin was revised as polaro method and TLC method.' - Both methods are being studied by the Health and' Welfare Ministry at the request of JHPA. Relevant values are indicated in Tables 2 and 3. .. ; \V~ _. .... .(4) Vinyl Producers" Understanding".^...-'-. T' . ' " In February 1973 a large amount of cadmium was detect ed in the wastewater treated at. disposal plants in Tokyo and Yokohama. - The metal was' tracsd.to PVC products. The public outcries that ensued prompted, the Japan Vinyl Goods Manufacturers to issue a statement to the effect , that cadmium would not be used. The statement, dated April 19, 1973, gave a one-year grace period before such under standing would take effect. --au'u (5) Labo? Safety and Hygiene - .vt.'^r.iri O'- :7_ 3;VT-- gredients, storage and handling Instructions, effects'^ health and other relevant matters. Such harmful substances are listed in Article 18 of the ordinance that implemented the law. Two items pertaining to PVC stabilizers on the list. They are cadmium and lead compounds. ^H^se are indicated in Table 4. (6) Poison Control * ` The Law for the Control of Poisonous Materials, the imple mentation of which is under the jurisdiction of the Health and Welfare Ministry, deals with substances which harm man's health when they are either taken into the body or directly handled. Two other laws designed for similar pur poses are in force. One governs the Drugs, Cosmetics and Medical Instrument Act; the other concerns household items containing poisonous substances. . Both statutes-are alg/ under the ministry's jurisdiction. ; - ___ .... (7) Pollution Control Legislation ; . Legislation is established concerning the disposal of harm ful waste and deaning.. .The Health and Welfare Ministry is responsible for this. `Under the jurisdiction of the En vironment Agency are the following four laws: The Clean Water Law, the Clean Air Act, the-Foul Smell Control Act, and the Agricultural Soil Pollution Control Law. 'Specificrestrictions applicable to stabilizers are indicated in Table 5. - The Law-Concerning Labor Safety and Hygiene went into effect in October-1973;- This law, for which the Labor Min istry is responsible; is designed to prevent accidents involv ing workers on the-job, ensure the safety and hygiene of workers in their work places and promote their health. Article 57 made it mandatory to identify substances injuri ous to health and -their compounds by indicating their names, chemical- compositions, the content of harmful in- Legislation pertaining to waste disposal obligates producers to treat their industrial waste on their own responsibility. Such waste is dassified into two types: harmful industrial waste and-ordinary or nontoxic industrial waste..:: Prime Minister's Office ordinance No. 5 (1973) governs the former type of industrial waste. It prescribes mefhods for treat ing such waste, containing various heavy metals-^ These methods also vary depending on metal content. " .fVi m . T10 r-> 1*n ***** * _> % - ?:i- j'r-. }-m ` 3 Application standards of Health & Welfare Ministry DirtctiT*-No. 178^:- Cases for application - Inapplicable . Containers and ; For foods eaten after- peeling. (e.g. eggs, oranges) ^ packaging - - materials : Those p( .which .food-contact ..surfaces; are_coated--'or la- initiated with other materials. .... . ... . Food.items packaged individually -in paper . A" .-..... , . Films wrapping-only taps of food-containers fegvcapf .seals for bottles of alcoholic beverages) * PVC labels applied to- outside ef food packaging materials - * other than PVC - ............... Tnstmments ",-- When hose for water'sprinkling is used for foods or -.'-beverages. - .........- ' - Rigid PVC pipe for water service (covered -by Water - Law) ....... t-J-?. rir.. JO r- When rigid PVC pipe is used for transport of foods, raw - PVC gloves used for washing foods . materials, or water in factory premises '" CO "T PVC tanks and PVC-lined tanks for storing foods or their raw materials ................ CO Chopping board of PVC'; * "* ml Cooking gloves of PVC ' O (Materials that come in contact with foods) o> - ..Filter doth of PVC fiber - .t - Table 4 Stabilizers related to Labor Safety and Hygiene Law Substance involved Item Indication [ Cadmium stearate Cadmium compounds `| Cadmium/barium l stabilisers Lead compounds if Lead stearate { Basic lead sulfate l Lead phosphite Regulations for prevention of damage due to special chemical substances - - Regulations for - _ , prevention of lead poisoning Caudon in manufacturing and handling - Class 2 substances . Applicable - 5 9^s for specific disposal methods, such as landfill, laciae* These substances will be tested by various neutral bodies y^atioo, sad water discharge, tolerances vary wnh changes including the Chemical Products Testing Association. Gov / ^ physical and chemical conditions under which the waste ernment agencies under the jurisdiction of the Health and is treated. For example, such variables depend on whether Welfare Ministry, and the Food and Chemicals Safety Cen J^^given substance is liquid, whether it is decomposed, ter. Tests will be conducted on such items as decompos- l^Eer it generates a toxic gas. or whether h. is subjected ability and residual toxicity. New substances will also be to additional treatment. Careful attention is needed in all tested to determine whether they are toxic, and if so, how cases where such toxic industrial waste is handled. This toxic they are. -- goes especially for processors and fabricators who are con The screening law described above is a unique piece of cerned primarily with formulations of auxiliary raw ma legislation which has no parallel in other countries. There terials. Cadmium and lead, two toxic heavy metals of are, of course, some problems that have to be tackled in major importance, are used in stabilizers and pigments order to make it really effective. For example, compli (cadmium sulfide, cadmium selenate,. chrome yellow, chrom ance to rigid standards must be ensured for all substances Vermillion, white lead, red lead, etc.). ' _ * V. which cover a very wide range of fields. There is also (8) Screening ol Chemical- Substances --* `Pollution is caused in the ecological cycle as- chemical substances are produced, consumed,- discharged-or other wise discarded. During the 64th extraordinary Diet session, dubbed the "antipollution Diet," as many as. 13 legislative bills were enacted, all of them dealing with pollution con trol., . / ~v.v Residual toxicity from agricultural.. chemicals and PCB poisoning are ^examples of the effects which the unintended the problem of the time-consuming process that must be followed to determine the safety of specific compounds. Moreover, accuracy in various testing methods must be guaranteed and workable standards established for- such analysis. It is more important to create- an overall system that would preclude any mistake or irregularity such as happened at the Japan Analytical- Chemistry Research In stitute. ^ - - -r ;`i 5. Stabilizers and Present Status oP Stabilizer Industry , intaVt* of chemical substances into- the human system would The PVC industry, as has been described, is producing cause. The Law for the Screening of Chemical Substances, a wide variety of polymers- including- copolymers. - These passed by the Diet on Sept. 18, 1973 and promulgated on polymers are processed and fabricated-into a broad spec Oct 16, 1973, is designed to prevent pollution and health trum of finished products by adding-very small amounts problems caused by such chemical compounds. of stabilizers, of which there is- also a. wide variety. - De The significance of this law lies in the fact that while velopment of such processed PVC products has created a the" laws governing the discharge of waste substances re solid market for them at home and abroad, - - -- gulate their "outflows" this particular law control?-1 "inflows" A colorful range of compounds that have been developed, of toxic substances through prior screening.. In this sense notably stabilizers and plasticizers, is also-a major factor s a positive meaning. The law, under the jurisdiction in the development of original processes and solidly en e Ministry of International Trade and Industry (Mill), trenched markets. Contributing to this was, of course, es the prior screening system to general industrial .unique processing technology of a-kind that is not available chemicals. This marks an improvement on the conventional---in- other polymer'industries. -A -list-of -PVC .products-is system which governs only pharmaceuticals and food addi schematically presented in Table 6. tives. Restrictions are now imposed on the production, im Selection of PVC stabilizers is a difficult problem (recom port and use of ail chemical substances that cause or may mended formulation) for compounders and stabilizer mak cause injury to human health or.to the living-environment.-' ers.- Since this forms the core of PVC processing tech Japan's chemical industry, is making a concerted effort nology each producer boasts unique know-how. This means, to draw up a comprehensive list of chemical substances that of . course, that., stabilizer? .are selected and evaluated by are currently available.^ MOT is lending positive guidance - different standards, depending on the facilities and pro to the industry in the preparation of such a list, A final- . cesses available to individual processors. Moreover, Ejec list was announced in ApriL tion of stabilizers or lubricants has a direct bearing on the --s Table S Statutory restrictions concerning"prevention of pollution of natural environments- Law- Item Cadmium and its compounds Waste Disposal & Cleaning Law Cmg/1) 0.3 as Cd Clean Water Law (tng/1) . I `u .Clean Air Act (mg/m1) 0.1 as Cd '"-V-l -*. "Harmful substances as Cd % Lead and its compounds . x-,; -* 3 as Pb , w y.. - .. Arsenic and its compounds Regions other than pH waters pH waters n-hexane extracted mineral oils . n-hexane extracted animal and vegetable oils Phenol content Zinc content . Chlorine and hydrogen chloride . 1-5 as As . 1 as Pb 0.5 as As (5.8-S.6) C5.0-9.0} 5 .30 5 5 `' Harmful substances as Pb 10 i* * .*.* - * Harmful substances 30 as Cl* : SO as HC1 . W Note: Figures Indicate test liquid analytical values prescribed by the respective laws. 4fi Ch mica! Economy &. Engineering Review R&S 131108 i Ingredients s'.?. ..Tables Manufacture of PVC articles Main Types Amounts Used Main Processes mass ' improvement of productivity and on the degree of rational ization. This question also has a critical effect on PVC compounds since the performance and behavior of stabiliz-ers determine the quality and function of each and product., The process of selecting PVC stabilizers and other com pounds and giving the best performance possible to end products is referred to as performance chemistry. In other words, the main objective is to produce market-oriented products. Stabilizers are precisely such a kind of products, and it is few this reason that applied technologies such as blending and preparation of formulations have been develop ed. Stabilizers are classified and typical products listed in Table 7. ... .. . ,v. .. ,* (I) Lead Stabilizers . Lead as a stabilizer has been used for a longer period than any other stabilizer. Initially basic lead carbonate was used. Later tribasic lead sulfate, dibasic lead stearate, ipad stearate, and dibasic lead phosphite came into use. Current stabilizer production in Japan is 50,000 tons a year, of which lead stabilizers account for 50 per cent in volume and over 30 per cent in value (estimated at 5,500 million-- 6,000 million). Tribasic lead sulfate and lead stearate are the two main stabilizer components which are being produc ed at a rate of over 20,000 tons annually. Lead stabilizers, along with cadmium ones, have the best heat and weather resistance. They are low in price; its high workability ensures high productivity; and they have excellent dielectric property. Although they have draw backs (i.e., transparency and sulfurization) lead stabilizers have been used widely in such areas as pipe, profiles and electric wires and cables. In recent years, however, the problems of environmental Table 7 Classification of PVC stabilizers Type of stabilizer . Lead compounds Metal soaps Organotins. Organic nitrogen compounds Organophosphites ... Epoxy oils Lubricants - Light stabilizers Antioxidants ` Typical product Tribasic lead sulfate ' '- Barium cadmium laurate--- Dibutyltin bis-octyl thioglycolate Aminocrotonate esters ' . .* Tripbeayl phosphite .i-.'' , " Epoxy soya oil . 1^ Glyceryl ridnoleate ' ' ..1 " Benzotriazoles .. . .I'____ 2, 4 diterriaiy butyl p-cresol pollution and labor hygiene have prompted moves to recon sider the use of these traditional stabilizers. In 1973, as has been described, the PVC industry changed course in favor of nonlead stabilizers. Later the use of cadmium was discontinued. At present active research and develop ment work is under way to produce new types of stabilizers. These moves to prohibit the use of toxic compounds gain ed momentum because of restrictions imposed by Directive No. 178, despite the fact that such restrictions were vir tually eased through the revision of this directive in the winter of 1973. The amendment, as has been described, was made in Directive No. 340. In the pipe industry^kj main user of PVC, most producers completed the manufacture of nontoxic pipe during 1973. Efforts are be ing made this year to perfect a formula that is economical ly feasible. Development of such a formula is expected to open the way for the establishment of a new system ade quately prepared to meet more stringent environmental rfr ay frictions that arc likely to be imposed in the. future. ed as compounds containing either one metal or two or Some processors are said to have given up their projects mere metals. to develop coaioxic stabilizers in view of the fact that the The performance of these metal soaps can be rated dif ban on lead and cadmium was virtually lifted in Directive ferently, depending on metal content, the type of acid, 340. However, the trend for contorric pipe, which is combinations with other stabilizers (e.g. phosphite, epoxy. eady available on the market in Japan, is here to stay. Restrictions are now imposed on the production, marketing and use of llad stabilizers and lead-based pigments- More oil, antioxidants), and the synergistic effect. -L ^ Metal soap stabilizers are also available in the solid or~ liquid state, or in the form of paste. Physical appearance specifically, the Clean Air Act and the Law Concerning depends on the type and amount of additive used prior to Labor Safety and Hygiene specify stringent standards for blending. The way this is done has a vital bearing on - " i v suspended particulates, dust and scot that are generated synergistic effect. These metal soaps demonstrate excel-. - during the manufacturing process (e.g., dissolving, sinter lent performance in the calendaring and extrusion of flexible- ' ing and drying), in the distribution stage and in the pro PVC products. They are also highly rated in the field of cessing of PVC. Similarly stringent restrictions are also plastisoi. . imposed on cadmium and its compounds. It is therefore Soaps containing a high level of powder cadmium have-^-7 V. a question of time that lead will disappear from-the PVC been used in the past not only-for-flexible PVC products vV industry. - but also for rigid PVC products- Compound stabilizers In the electric wire and cable industry,- which' is still such as cadmium-barium, barium-zinc, and calcium zinc-- dragging its feet in stopping* the use of lead, antilead moves all of which are typical examples of stabilizers that have- are also gaining momentum. It is notable in this connec the greatest synergistic effect--are.used extensively in a- 1 ;rV tion that progress in projects to discontinue the use of lead - broad range of products. For instance, these include foot---.-L; and cadmium varies from region to region-. Regional dif wear, sheet leather, foamed products, film, flooring ma-4^ -- ferences also exist in producers* attitudes toward such proj terial, sundry goods, and parts for industrial machines and ects:-For instance, in areas around Lake Biwa, where equipment. Calcium-zinc soaps are- most widely -used in - . strict restrictions-are imposed on the-siting of plants and "many countries in such areas as .containers, packaging fLLm.T^' V- on the discharge and disposal of industrial waste, corpora - and foil. In Japan cadmium-barium stabilizers have proved tions are much more eager. to do away with these toxic highly effective in the production of agricultural Aim. . -X elements than those in other regions. - `1 - ` These soaps stabilize the quality of PVC because of the (2) Metal Soap Stabilizers - This type of stabilizers are being used widely, holding the second largest share in total production-after lead. Metals used mainly in these stabilizers are barium, .cad mium, calcium, and zinc. Magnesium and aluminum- are ^Bed in small amounts. These and organic acids are the BKn ingredients of metal soap stabilizers. They are offer- synergistic effect produced when these stabilizers serve as a receptacle for neutralizing the hydrogen chloride gas generated at the time of heat treatment. Japan's output of these stabilizers is estimated at 14,000-15,000 metric tons a year. In value terms this is equivalent to about 5,500 " million--7,000 million. The total production breaks down as follows (estimated): cadmium group--over 5,000 tons; barium group--over 4,000 tons; calcium group--under 3,000 _ s - - .7 V -- Table S - Stabilizer consumption in.Western - Europe----:---- actuals and forecasts -- L By stabilizer (In metric tons) tons; and zinc group--under 2,000 tons. ,;(It is difficult to obtain classified statistics for metal soaps including com- pound soaps.) - .'............ . The most typical of metal soaps is the cadmium-barium system which has the greatest stabilizing effect However, ;.v - ; Lead Cadmium/bariunt - 1970 . . 35.550 - - - --- 1^970 - 1976 ., 56,300 22,140 ` the occurrence of itai-itai disease, one of the internationally known pollution-induced anomalies, has prompted all Industries concerned to discontinue the use of cadmium during the past year. These moves were triggered by a "death ' -_.V .r .7 4,000 6,400 - sentence" that the Japan Vinyl Goods Manufacturer- Asso Tin f 3,100 8,950 - ciation passed on this toxic-metal.- Thus projects against -- Total 55,620 93,790 . 2. By country (In' metric tons) - West Germany Fiance Italy Benelux Britain Spain Sweden Denmark Norway _ Total 1970 1976 17,100 29,000 8,500 ..: 16,100 10,000 15.000 . 4,740 8,100 9.700 15,100 2,700 5.800 - 1,770 2,800 640 1,060 470 830 55,580 . 93,790 lote: As stated before, PVC stabilizers are used a* a con siderably low rate in Western Europe. A high rate of use may be a feature limited to Japan, or it may be that European - countries have much room for ra tionalization. Prospects for cacmium/barium stabilizers may cot be as bright as indicated for the case of Japan. Table 9 PVC consumption in Western Europe (In thousands of metric tons) 1970 1973 (estimates) West Germany France Italy Benelux Britain Spain Sweden Denmark Norway Total _ 750 . ... 1,000 335 . 315 - 7 : . .* ; . 179 ----- - - 326 - 550 440 260 -4SO 3J yP (/) 96"T. 78 ' 29 21 ' 140 03 91 33 -J. O 26 - to 2,179 2,990 Note: Since European countries, like Japan, are suffering from . shortages of equipment and commodities, prospects for 1973 are not dear. The figures should serve better for comparison rather than as absolute values for in dividual countries. . PhMnii-at Frnnnmv A Encineerimr Review R&S 131110 J/fcrihini are ____ .eadway than antilead projects. /Tiie current trend is toward the used of low-toxic or con- oxic systems, notably barium-zinc compounds (low-toxic) ind calcium-zinc compounds (nontoxic.). The sole excep- jon is agricultural film used for cermin purposes, which -equires analysis tests for an extended period of obtain the necessary data, including exposure data (which must be rollected over a-, period of over two years) and weather- ability data. It should be noted that epoxy oil. organophos- phites, and tin-based stabilizers, all of which are in these combinations, contributed to making it technically possible to effect a change to these low-toxic and nontoxic com pounds. Calcium-zinc stabilizers are considered most desirable from the viewpoint of environmental protection.- However, these are essentially not effective in terms of heat and weather resistance unless some auxiliary agents are added. Not only that; the scope of utilization in processing is also limited. For this reason more merchandize design work is needed. This results in an increase in- the variety of processed products and imposes an added strain on pro cessing and operating personnel. ; . ..i. Producers are now developing "one-pack" stabilizers through technological exchange with users as one way of rationalizing the production system. Resolution of the prob lems cited above is naturally part of such rationalization efforts. : (3) Organophosphite Stabilizers ? Stabilizers in this category consist mainly of phosphites containing triaryl, trialkyl, or a combination.of alkyl and aryl. These stabilizers are always used in combination with other stabilizers so that heat stability can be synergisticaily improved. In cases where a phosphite is used with a metal soap the appropriate dose is 0.5--1.5 PKR. A metal chloride chelator that is formed through PVC stabilization serves to improve heat stability. The effect of combination with lead or tin is not as large as that given by the addition of a metal soap. Statistics for the past one or two years show that about 1,COO metric tons of phosphites are being used annually for stabilizers. This quantity is worth an estimated 700 million.-' ` `.- :. . .. (4) Organic Tin Stabilizers . / ' *. - ' These organic tin derivatives are based on organic acids or mercapto compounds, consisting chiefly of butyl tin and octyl tin. This basic difference between these two alkyl groups is that octyl tin is being used in various countries because it meets the requirements of safety and hygiene relevant regulations and is therefore being applied increas ingly as a nontoxic stabilizer component. In general, tin-based stabilizers are relatively expensive, their prices depending largely on the price of the metal. But tin stabilizers are more effective than any other type of stabilizers. They have been used mainly in the area of rigid PVC, especially in those final processed products in which a high degree of transparency and surface finish ing are of special importance. Tin stabilizers impart ex cellent heat stability to these products. Certain tin stabilizers contribute to improving light re sistance. Their effectiveness in this particular application may be further increased if an ultraviolet ray absorbent is added. Tin stabilizers also have been used in rigid PVC and in sol compounds although some restrictions have been imposed in economic terms. Formulations consisting of a combination of a calcium- zinc compound and a lubricant are considered essential to the replacement of cadmium-barium stabilizers in flexible PVC and of lead-based stabilizers in rigid PVC. These are deemed absolutely necessary in terms of both technology and performance and are expected to occupy the leading position in the stabilizer production unless some stabilizers of an entirely new type are developed. Progress in the development of applied technology for combinations for octyl tin, calcium-zinc, and a lubricant holds out much promise for nontoxic PVC products in pipe and other industries. The stabilizing mechanism of tin-based stabilizers varies according to the type of a stabilizer that is used in combina tion. As in the case of metal soaps, tha ester exchange of the PVC main chain is caused by tin, with the result that a stable configuration of five or six tin atoms is formed, thus stabilizing the chloro group in the PVC. Demand for tin-based stabilizers in Japan is estimated at 6,000-7,000 tons a year. Their prices vary with changes in the international quotations of tin; the prices have soared since last autumn. It is expected that the share of octyl tin stabilizers will expand, thus further raising the average price per unit weight. At present the prices of tin-based stabilizers range from 1,200 to 3,000, per kilogram. A new type of methyl tin, which is said to comparable to octyl tin in terms of toxicity, is being imported into Japan from the U.S., where it has not been approved by FDA for use. in the food industry but under NSF standards is applicable to water pipes. In West Germany, BGA is ex pected shortly to authorize the use of this substance, while in Britain, BPF is said to have sanctioned its use. In the manufacturing process of this methyl tin stabilizer, par ticularly at temperatures around 20Q*C, trimethyl tin is generated. It is the toxicity of this trimethyl tin that poses a problem. ........ . , (5) Organic Nitrogen Stabilizers This kind of nonmetal compounds is the best stabilizers. Stabilizers in this group now being used in PVC are amide compounds containing nitrogen. These consist of the follow ing three types: (1) diphenylthiourea, (2) alpha-phenyl indole, and (3) aminocrotonate ester. All these have less stabilizing power than the stabilize)^ mentioned above. Alpha-phenyl indole has excelleont he stabilizing effect but it has poor resistance to light. The reason why these nitrogen-containing stabilizers are receiv ing keen attention despite their drawbacks is that interested authorities in major countries have approved the use of them for packaging containers. -- ' In fact, these compounds are being used rather extensively in combination with calcium-zinc stabilizers or actyl tin stabilizers. In France, for instance, these nonmetal stabiliz ers are being widely used in blow-molded bottles for wine and oils. In Japan consumption is so small that it is not even indicated in relevant statistics.. However, nommetal organic stabilizers offer great promise in the current efforts to develop new types of PVC stabilizers in Japan and abroad. (6) Epoxy Oils This series of additives are important auxiliary stabilizers rather than plasticizers. Main products are epoxy esters of vegetable oil (e.g., soybean oil) aad epoxy monoesters of unsaturated fatty acids (e.g., oleic acid). These can be used in combination with all types of stabilizers in both flexible and rigid PVC. Only a small dosage can have a great heat stabilizing effect because the chlorohydrin com- p und formed by such a stabilizer acts as a receptacle for hydrogen chloride. ... 6. Lubricants The function of a PVC lubricant is as important to pro cessing and fabrication as that of a heat stabilizer. Jhe role of lubricants, used either singly or in combination^B two or more kinds, is particularly important in the pFocessing of rigid PVC. As is the case with stabilizers, the selection of lubricants has a direct bearing not only on the properties of end processed products but also on workability r ( productivity. There is a wide variety of lubricants, as will be describ ed later, with each having a different chemical structure ^^physical appearance. These are dassiSed broadly into ^Htypes: internal lubricants and external lubricants. This classification should not be taken to mean, however, that there arefactually two distinct types of lubricants--one designed strictly for internal application, the other for ex ternal application. Their functions are cot defined in such a clearcut manner. In general, external lubricants act be tween the metal surface of a processing machine and a PYC polymer. Compounds of this type have poor com patibility with P.VC. At temperatures at which PVC is pro cessed, they easily exude on polymer surface, forming a lubricant layer on the unit particle surface of PVC. As a result, gelation of the resin is delayed. Internal lubricants have great affinity for Pyc. At the fimo of processing, therefore, they help reduce the melt viscosity or PVC,. ensure an adequate flow of the compound involved, and mitigate the friction heat generated by the shearing force. Lubricants are available in the solid or liquid state. They can be dassii&d roughly into the following groups: fatty adds, fatty add. esters, fatty alcohols, add. amides,, metal soaps, and hydrocarbons. . 7. Antioxidants v PVC products for outdoor use, such as sign boards, tar paulins, and awnings, require not only heat stability but also good resistance to light and weather. Many heat stabilizers contribute more or less to iraprov- the light resistance of PVC compounds. In general, klor phosphite-based stabilizers have a conspicuous effect nparting light resistance. Metal soaps combined with organic tin maleate or phosphite are similary effective. Antioxidants are used where a higher degree of light fast ness is needed. Among the compounds used for this pur pose are azole derivatives, benzophenone derivatives, organic phosphoric compounds, and `special amine derivatives. These are used either singly or in combination with heat stabilizers. ... .. ..... ... .... ...; : 8. Plasticizers and Extenders - With the exception of epoxy oil, it is not appropriate to include these compounds in the same category as stabilizers. Plasticizers are the main material used in the production of flexible PVC. These are classified into three groups: primary plasticizers, extenders and secondary plasticizers (auxiliary epoxy stabilizers). Primary plasticizers include the following types: phthalic add compounds (annual production exceeds 350,000 tons), phosphoric compounds (under 6,000 tons), esters such as those of citric acid stearic acid and fatty acids .(10,000 tons), dibasic acid derivatives (e.g., sebacic and succinic adds), and polymeries. These plasticizers tend to decom pose through oxidation at high temperatures, yet they con tribute variously to increasing the stabilizing effect on PVC. Drawbacks in property can be overcome by adding a small amount of antioxidant to the plasticizer to be used. This is now practiced. ^tastidzers based on phosphoric acids are designed chiefly ^^nprove the flame retardancy of ?VC products. But taHe also have an excellent plasticizing effect which helps reduce the melFtemperature of the resin. In general, com pounds in this category impair the heat and light stability of PVC polymer although efforts have been made to mini mize these defects. As things stand now, these piastcizers do cot hold out much promise. As for plasticizers based on citric add, acetyl tributyl citrate is a typical example. Food packaging and medical equipment are the main area of application. The strengthen ing of food safety and hygiene standards and the toxidty of phthalic add esters are responsible for the recent ex pansion of demand for this type of plasticizers. In Japan no such compounds are being produced; demand is being met by imports from Akzo of the Netherlands and Pfizer of the United States. Polymeric plasticizers are used to improve the low-tem perature characteristic and extractability of PVC com pounds. They are especially effective in areas such as insulation cables, which are exposed to relatively high tem peratures for a long period of time- For this reason these plasticizers are widely used in fields where more sophis ticated applications are required than those usually offer ed by primary plasticizers. - Extenders indude long-chain hydrocarbons or their chlorinated compounds. At present; the latter group of extenders are being used. The problem, however, is that the presence of chlorine causes interferences with the metal in the stabilizer, thus impairing the stability of the whole PVC compound. ,v 9. Fillers - ,- 44 SO _ V -- -. - 1 _ ; . _____ __ ___ , ; Fillers, like extenders, are used generally to reduce the overall cost of PVC compounds. These are also used in the production of nontransparent products or products that have special physical or chemical features* Addition of fillers to PVC compounds has, of course, a close bearing on the properties of end products. For example, the use of certain fillers results in a drop in tensile strength. Though not as versatile as polypropylene polymers, fillers play an important role in improving the impact strength of processed products. A wide variety of fillers are avail-. able, including those in the form of carbonate, silicate, alu minum salt, and asbestos. It is said that addition of a silicate contributes more to the stability of the whole com pound than does a carbonate or an aluminum salt. Asbestos, a low-cost filler, is used in floor tiles, for example. Asbestos fillers not only have a great stabilizing effect but also make it possible, depending on the stabilizer used together with asbestos, to eliminate unstabilizing factors that are caused in the PVC compound by the presence of asbestos. 3 J "i;1 I -a -ii 10. Pigments '*' * Pigments differ from those additives described above, not ably stabilizers. Below only those pigments which have a bearing on stabilizers or stabilizing effect will be described. Pigments are used to improve either physical appearance or performance, or both. In the former case, and products are colored with pigments to increase their value added. Titanium white is most widely used as pigment in PVC field. Normally its concentration is below 5%. The effect of this pigment on stability is practically nil. But it should be noted that titanium white has a great effect on the plateout phenomenon especially in the case of calcium-zinc for mulations. Some pigments are designed to improve both the stability and the physical appearance of PVC products. In the past, red and yellow pigments based on cadmium have been used because of their excellent pigmentation and their out standing color fastness. These additives, however, are no longer used because of the toxicity of cadmium. The re placement of these pigments by harmless ones was almost completed during 1973. Blue and purple pigments are used for "blueing" design ed to eliminate the color that develops during initial decom* 33 R8 (/) w position of PVC which occurs ar the true of processing. These are essentially the same as other polymer additives. a# 11. ^losing Remarks The PVC industry has developed to date a very wide range of additives and plasticizers and has accumulated in the process a broad spectrum of unique compounding and blending techniques which make it possible to use these compounds as essential auxiliary or assistant materials for PVC prodfcts. And development of unique processing tech niques, machines and processes has contributed to opening up new vistas of possibility in an ever-growing market. The diversity of the PVC industry Feints to two signifi cant factors when it is considered in comparison with other polymer industries. One is the fact that PVC decomposes by dehydrochlorination. The other is related to the first factor;, it is- the great, role played by heat stabilizers the use of which is necessary only for PVC polymers precisely because of the instability due to hydrogen chloride. Diversity also has been a factor of practical importance to those who work, in various PVC-related industries--in the sense that attractions and incentives offered by the broaden ing horizon of the PVC industry have implanted in their tninriit a strong willingness to open new "frontiers.". This is the reason why PVC has come- to occupy the central and leading petition in the family of thermoplastic resins. There are some problem areas, however, which call for rethinking on the part of the industry. Looking back on the history of the Japanese PVC industry one readily notes that this industry has- followed a different course from the path treaded by other polymer industries- In the PVC in dustry, which is an offshoot of the rubber industry, com pounding techniques used in the molding and processing of rubber products were given prominent attention. In other polymer industries, however, raw materials supplied by polymer producers were molded and processed directly. ' - This peculiarity of the PVC industry lends special sig nificance to PVC compounds. In other polymer industries the coloring of compounds was the main objective, but PVC compounds are quite different, not only in processing tech nology but also in the mode of distribution. The historical link with the rubber industry, however, left some stabilizer makers and molders in technical backwaters. The time is past when PVC compounding was a sort of closed busi ness in which know-how was traded on a piecemeal basis. A long time has elapsed since the belief gained groi^i that polyester is the last general-purpose polymers. ever, a breakthrough can still be made in the plasticsW dustry through improvement of existing polymers and of blending techniques using a wide variety of additives. The process of producing stabilizers consists of two major stages: synthesis, and blending and formulation. Stabilizers, which may be referred to as fine chemicals, represent only part of the work done by stabilizer makers. The bulk of their work involves applied technology which brings them into dose contact with other compounders and moldings makers as well as with their customers. The term "tech nical service" is perhaps a misnomer here, because what is involved is not a system of experties or know-how per taining to PVC processing agents but "trial and error" type collaboration on the job, or work of a kind which we call "technical field service." .... The diligence of the Japanese people has made it pos sible to produce a wide variety of end products from PVC, making Japan the No. 1 -PVC producer in the world both in name and in substance. ' - .. But the PVC industry finds. itself in difficult, circum stances. With environmental standards expected to become more stringent, there is a great need to promote coopera tion among the three major parties concerned: polymer producers, the group of PVC moldings makers, compound ers and stabilizer producers, and processing machine makers. In Europe such a trilateral system of collaboration was developed a long time ago. It is hoped that in Japan, too, a similar system will be established as soon as possjjk so that all the industries concerned can take joint ac^P to promote projects of common interest to them. With the PVC industry now gearing up for an era of nontoxic com pounds, now is the best time to make a start . R&S 131H2 August 1974 Vol. 6 N . 8 (No. 75) 51