Paints, Coatings and Solvents Episode 10 doc

14.4. Tosicologj, und Orci~pationril Health 305 14.4. Toxicology and Occupational Health 14.4.1. Toxicology [ 14.103 a] Acute and Chronic Toxicity. Solvents act with different intensities on human, animal, and plant organisms. Their effects depend on the amount of solvent and the exposure time. Under short-term exposure to high solvent doses acute damage may occur, whereas the absorption of smaller amounts over a longer period leads to chronic damage and sensitization. The chronic effects are more dangerous since they are accompanied by an acquired tolerance, with the result that they are often not detected early enough. In order to evaluate the solvent toxicities, their LD,, values (oral administration to rats) are listed in Table 23. Since most cases of solvent poisoning are caused by inhalation of solvent vapors, the LC,, values are also given. Inhaled solvent vapors pass via the lungs and blood circulation into the body, where they accumulate in tissues with high lipid content (e.g., nerves, brain, bone marrow, adipose tissue, liver, and kidneys) [14.104]. The cells can either be damaged by the solvents or by their decomposition products. Solvents can also pass into the body via cutaneous or, more rarely, gastrointestinal absorption [14.105], [14.106]. Symptoms of acute solvent poisoning include dizziness, drowsiness, headache, loss of consciousness, and narcotic effects which are attributed to disturbances of the central nervous system. Chronic poisoning is initially undetectable, but subsequently causes damage to organs that are specific for each solvent [14.107]-[14.110]. Solvents have two effects on the skin: (1) they dissolve the natural fatty layer, the skin therefore cracks and microorganisms and dirt particles can penetrate more easily and cause infection; (2) solvents can act directly to cause inflammation or blistering. The following solvents are absorbed very readily through the skin and pass into the body: aniline, benzene, butyl glycol, butyl glycol acetate, dimethylacetamide, dimethylformamide, dioxane, ethyl glycol, ethyl glycol acetate, ethylbenzene, iso- propyl glycol, carbon disulfide, methanol, methyl glycol, methyl glycol acetate, methylcyclohexane-2-one, 4-methyl-2-pentano1, nitrobenzene, nitrotoluene, iso- propylbenzene, 1,1,2,2-tetrachIoroethane, and tetrachloromethane. After sensitization of the skin or respiratory system, allergic reactions may occur but vary widely, depending on the individual susceptibility. Observance of the MAK or TLV values is no guarantee against the occurrence of such reactions [14.111]. Turpentine oil is the only solvent that has attracted attention because of its ability to trigger hypersensitivity reactions of an allergic nature. Investigations have shown that some liquid products have carcinogenic, mutagenic and reproduction toxic (including teratogenic, embryotoxic) properties. The carcinogenic, mutagenic and reproduction toxic properties in the EC classifi- cation are, in the jargon used, referred to as “cmr” properties [14.103a]: c: carcinogenic -+ causing cancer m: mutagenic + altering genetic material r: reproduction toxic -+ hazardous for reproduction The EC classification of “cmr” substances uses categories 1,2 and 3 (see also TRGS 905). 0 Category 1: Substances which are known to have this property (c, m or r) in humans. 0 Category 2: Substances which have shown this property to date unambiguously only in animal experiments. It must be assumed that this is applicable to the human situation. Substances for which there is cause to suspect that they have this property. Information for a satisfactory assessment is available. 0 Category 3: The classifications of the German “MAK Committee” in respect of these proper- ties in some cases differ considerable from the EC categories, which are binding in the final analysis. In future, all the national classifications will lose significance, irrespective of the European country. Carcinogenicity. The central principle for protection when handling carcinogenic substances in section 6 of the german Gefahrstoffverordnung (hazardous substance regulations) is, after the replacement requirement, the requirement to minimize exposure. For substances in categories I and 2, no MAK value is fixed because it is not possible to indicate any concentrations which can be regarded as safe. If use of these substances is necessary in industry, special protection and monitoring mea- sures are needed (see the german Technische Richtkonzentrationen). Particular care is also necessary when handling substances in category 3. The substances in catego- ry 3 are divided into subgroups 3a (substances whose toxicity has been extensively investigated) and 3 b (substances not yet adequately investigated). Examples of substances in categories 1 to 3: Category I : Benzene Category 2 : Hydrazine, butadiene, 1 ,2-dichloroethane7 hexamethylphosphoric- acidtriamide, 2-nitropropane Category 3 : Aniline, chloroform, dioxane, ethyl chloride, methylene chloride, pen- tachloroethane, 1 ,I ,2,2-tetrachloroethane, 1,1,2-trichloroethane, te- trachloroethene, tetrachloromethane, trichloroethene. Classification by the “MAK Committee”: The “MAK Committee” assigns carcinogenic substances to groups 111 A and 111 B. The unambiguously carcinogenic substances are in turn divided into two subgroups, similar to the subdivision made by the EC Commission : I11 A: I11 A 1 : Substances which, as shown by experience, may cause malignant tumours in IIIA2: Substances which have as yet clearly been shown to be carcinogenic only in 111 B: Products unambiguously proved to be carcinogenic humans animal experiments Substances for which there is cause to suspect a carcinogenic potential. The use of 111 A and 111 B results from the divisions in the MAK list: I I1 List of substances 111 Carcinogenic products IV Sensitizing products V VI Particular products. Relation between the classifications of the MAK Committee and the EC: Significance and use of the MAK values Dusts and smokes (suspended particles) Carcinogenic products MAK classification EC classification 111 A1 111 A2 111 B Category 1 Category 2 Category 3 a and 3 b Mutagenicity. Mutagenic means causing damage to male and female germ cells, resulting in genetic alterations in the progeny. This damage may take the form of genetic mutations, or alterations in the structure and number of chromosomes. Examples of substances in categories 1 to 3 (EC classification): Category 1 : No substance has yet been included in category 1 Category 2: e. g. Hexamethylphosphoric-acid-triamide, ethylene oxide, ethylen- imine, diethyl sulphate, acrylamide Category 3 : e. g. 4,6-Dinitro-o-cresol Reproduction toxicity. Reproduction toxicity defined in the EC classification em- braces two independent properties : 1. Substances which impair development of the unborn child (impaired develop- ment; Symbol RE) 2. Substances which impair fertility (Symbol RF) As described above, the EC classification makes use of the usual three categories for each part. The term impaired development embraces not just the occurrence of anatomical malformations (teratogenic effects); on the contrary, it also includes growth retarda- tion without changes in organs as well as impairments of mental development. Examples of development-impairing substances in the EC classification : Category RE 1 : Category RE 2 : Lead chromate, lead acetate Ethylglycol, methylglycol, ethylglycol acetate, methylglycol acetate, dimethylformamide In contrast to the EC, the German MAK Committee takes only the embryotoxic effect of substances into account. Whereas the classification of the MAK Committee only provides information on the inhalational exposure at the relevant limit in air (MAK), the classification of the EC Commission follows the generally valid scheme without reference to a limit for the workplace. According to the MAK classification, the embryotoxic effect is divided into 4 pregnancy groups: Group A: Certain proof of an embryotoxic effect. Harm cannot be precluded even below the MAK. No solvent has yet been put in group A. Group B: Embryotoxicity probable even below the MAK. e.g. 2-Methoxy- propanol, 2-methoxypropyl acetate, methyl chloride, chloroform Group C: There is no risk of embryotoxicity below the MAK. e.g. Ethanol, l,l,l- trichloroethane, 1,l -dichloroethene, tri- and tetrachloroethylene, n-hex- ane di(2-ethylhexyl) phthalate, 2-butoxy-ethanol, 2-butoxyethyl ac- etate, 1 -methoxy-2-propanol, 1 -methoxypropyl acetate, ethylene glycol, butyldiglycol, isoamyl alcohol, 2-isopropoxyethanol, isobutanol, THF, toluene, cyclohexanone, dimethylacetamide, styrene Assessment not yet possible. Group D: Relation between MAK and EC classifications: Embryotoxic substances Development-impairing substances MAK classification EC classification Reference point = MAK Reference point = oral intake Group A Group B Group C Group D RE 1 RE 2 and 3 no classification Fertility-impairing substances (EC classification): All substances classified as impairing fertility (RF 1 or 2) are at present also classified as impairing development (RE), e.g. Category R, 1 : Lead acetate Category R, 2 : Ethylglycol, ethylglycol acetate, methylglycol, methylglycol acetate In connection with the detection and assessment of dangers due to hazardous substances at the workplace (TRGS 440) and finding possible substitutes (“replace- ment requirement”), account must be taken of the industrial regulations of the 600 series, including in particular TRGS 609 (“substitutes, replacement processes and restrictions on use of methyl- and ethylglycol and their acetates”) and TRGS 61 2 (“substitutes, replacement processes and restrictions on use of dichloromethane in paint removers”). 14.4.2. Occupational Health Personal Safety Precautions. When working with solvents or solvent-containing preparations, contact with the skin and mucous membranes should be avoided. Protective goggles and gloves should be worn and the skin protected with skin cream. Wet articles of clothing should be changed immediately. Inhalation of solvent vapors should be avoided. The guidelines and codes of conduct published by the industrial and trade unions should be observed. Odor Threshold. Most solvents have a characteristic odor. Human perceptibility and sensitivity to solvent vapors depends on habituation, which varies markedly from one person to another. Odors that are regarded as pleasant in small concentra- tions may be considered intolerable at high doses and under constant exposure. Other vapors that are initially considered objectionable may subsequently be regard- ed as tolerable [14.3 121. It is therefore impossible to give objective rules for determin- ing when an odor becomes objectionable. Odor intensity is subdivided into four levels : 1) Imperceptible 2) Weakly perceptible 3) Moderately perceptible 4) Highly perceptible The odor threshold is the vapor concen ration in a cubic me :r of air (ppm) that is just still perceptible, [14.3 13].The odor threshold values of some solvents are given in Table 23. When handling solvents, the odor can be regarded as a preliminary warning sign but cannot replace necessary safety measures. Relatively high solvent concentrations may irritate the mucous membranes. It must be pointed out, however, that some mildly smelling solvents may present more of a health hazard than other, strongly perceptible products. MAK Values. The toxicity of solvent vapors at the workplace has been investigat- ed in animal experiments and by observing and monitoring humans. The MAK (Maximale Arbeitsplatzkonzentration) is the maximum permissible concentration of a substance in the atmosphere at the workplace that is generally not injurious to the health of the employees and is not regarded as intolerable by the latter, even after repeated and long-term exposure (generally 8-h exposure per day). As a rule, MAK values are average values over a period of a working day or a working shift. Since the actual concentration of the working substances in the inhaled air frequently fluctuates, uper exposure peaks are specified in the TRGS 900 section 2.3. Technical equipment at the workplace should be designed and dimensioned so that the MAK values of the individual solvents are not exceeded. No MAK values can be specified for a number of carcinogenic and mutagenic substances. For these substances the Technische Richtkonzentrationen TRK (low- est technically feasible levels) have been set to minimize the risk of a health hazard at the workplace. The TRK value for benzene and 2-nitropropane is 5 ppm (TRGS 102). Since the MAK values apply only to pure substances in the workplace atmo- sphere, an evaluation index IMAK has been defined in TRGS403 according to the following formula for mixtures of solvent that occur in the majority of cases at the workplace: where C, , C,, . . ., C, are the average concentrations of a working day or working shift of the substances I = 1, 2, . . N with MAK,, MAK,, . . ., MAK, that goes with it. TLV Values. In the United States, the equivalent of the MAK value is the threshold limit value (TLV). The TLV value is that concentration of a substance in the air to which virtually all workers can be exposed daily without any harmful effects. This value is subdivided into TLV-TWA (time-weighted average concentra- tion), TLV-STEL (short-term exposure limit), and TLV-C (ceiling limit). TLV-TWA applies to a normal 8-h working day or a 40-h week, TLV-STEL is the maximum concentration for an exposure time of 15 min, and TLV-C is the concentration that should at no time be exceeded. The TLV values published by the ACGIH are recommendations, whereas the PEL values (permissible exposure limit) specified by OSHA (Occupational Safety and Health Administration) are enforced by law. The safety limits are recommended to OSHA by NIOSH (National Institute of Occupa- tional Safety and Health). Solvent TLV values for the USA and several European countries are listed in Table 13. Other Limiting Values. In Scandinavia, solvent-containing products are identified with a YL value (yrkeshygieniskt luft behov = industrial hygiene air requirement). This value states how many cubic meters of air are required to dilute the amount of solvent contained in 1 L of product to such an extent that the concentration is below the TLV value. The YL value can be calculated for each solvent by multiplying the YL factor by the percentage content of the respective solvent in the liquid. A PWA Table 13. Threshold limit values of Germany and the USA (ppm, 1996) Solvent Germany (MAK) USA (TLV-PEL) C yclohexane 300 300 Diethyl ether 400 400 Ethyl acetate 400 400 Tetrahydrofuran 200 200 Pentyl acetate 100 100 Methyl ethyl 200 200 Methyl isobutyl 100 100 ketone ketone factor ( paint technology work hygiene air requirement) is allocated to the solvents on the basis of their YL value. The PWA number is in turn used as a basis for calculating the potential health hazard of a paint, and serves to specify the protective measures and working clothes that are to be used when applying paints (Swedish Work Safety Office Publication No. 463 and State Factory Inspectorate Publication No. 464. of 3rd August 1982). A harmfulness factor has been proposed to quantify the harmfulness of solvents [14.114]-[14.316]: 10 000 TLV . relative evaporation number Harmfulness factor = The harmfulness factor takes into account not only the actual health-damaging action of the solvent, but also the time for a health-damaging concentration to accumulate if the product leaks or is split. 14.5. Environmental and Legal Aspects 14.5.1. Environmental Protection Being volatile substances, all solvents inevitably evaporate and pass as harmful substances into the atmosphere [14.117]-[14.120]. They may also affect waterways, lakes, rivers, ground water, and soil. Anthropogenic organic emissions total ca. 12 million t/a in the EC; of this, 30% stems from the use of solvents and 45% from the transport and traffic sector (Corinair Study 1990, Inventaire europeen des emissions). United States. The first environmental protection measures were implemented in particularly threatened, highly industrialized regions with a high density of motor- ized traffic. In the Los Angeles district of California, exposure of certain organic solvent vapors to solar radiation can lead to the formation of photo smog [14.121]- [14.123]. In the United States, Public Law 84-159 of 1955 passed by the Federal Departments of Health, Education, and Welfare was the basis for local clean air directives. In Rule 66 and Rule 442 (district of Los Angeles), aromatic hydrocarbons (xylene, tetrahydronaphthalene, toluene, and ethylbenzene) and branched-chain ke- tones (e.g., isophorone, mesityl oxide, methyl isobutyl ketone, methyl isopropyl ketone, and diacetone alcohol) are classified as photochemically reactive, smog-pro- ducing solvents. Aliphatic hydrocarbons and nitro compounds are considered to be photochemically nonreactive. Efforts are being made to reduce the solvent content of paints and use photochemically nonreactive solvents or water. Clean air measures in the United States have become more stringent as a result of further laws passed by the EPA, including the Air Pollution Control Act 1962, Clean Air Act 1963, Air 3 1 2 f 4. Soll~rtlrs Quality Act 1967, National Environmental Policy Act 1969/1970/1975, Clean Air Act 1970 and 1990 (CAA) [14.124]-[14.127]. The implementation of these acts in the federal states is governed by executive provisions (e.g., New York State Rule 187). Since 1989, emissions have been regulated and reduced in stages by restricting the use of solvent-containing coatings in certain areas of application ; for example, specific directives apply to the use of paints in automobile repair workshops, air-drying industrial paints, wood paints, swimming-pool paints, and marine paints. Special regulations apply to new industrial sites (e.g., new automobile factories). Europe. An anti-emission law (Immissionsschutzgesetz) was passed by the state of North Rhine-Westphalia, Germany, in 1968. The purpose of this law and various executive directives was to improve living conditions and the atmosphere in the Ruhr district. In 1974, the individual laws of German states (Linder) were unified in the form of the Bundesimmissionsschutzgesetz (Federal Anti-Emission Law) and the Technische Anleitung zur Reinhaltung der Luft, TA Luft (Clean Air Regulations) of 27 Feb., 1986, which has since become known throughout Europe [14.128]- [14.131]. The following laws and directives currently exist in other European countries: Unirrd Kingdom. Environmental Protection Act with Air Pollution Control APC (1 990) [14.132]. Iidj~. Law 203 of the Ministry for the Environment (1988) including guidelines (1990) that restrict solvent emissions in certain application sectors (e.g., the automo- bile industry). Tlir Nrtherlunds. Guideline KWS 2000 to reduce aromatic hydrocarbon emissions by ca. 50% of the 1981 level by the year 2000. France. Guideline to reduce emissions of volatile organic compounds (VOC) by ca. 30% by the year 2000. Austria. Anti-emission law to reduce the use of solvents, particularly aromatic hydrocarbons [14.133]. European legislation is standardized by a guideline on Integrated Pollution Prevention and Control (IPPC) which restricts and controls emissions produced during the erection of new technical plants and the expansion of existing plants. The guideline will come into effect shortly. For solvents a european legislation will be standardized by the Solvent Emis- sions Directive that is currently beeing drafted and will become effective prob- ably in 1998. Its aim is a reduction of the ozone content in the troposphere by stepwise limitation of emissions of volatile organic compounds beginning with a reduction of 30 '/o until 1999 in comparison to 1990. In the long term there are plans to reduce the emissions up to 70-80%. Affected by the Solvent Emissions Directive are among others the paint and automotive, printing ink, metal de- greasing, wood impregnation, chemical dry cleaning and pharmazeutical indus- tries [14.134]. For the different solvents POCP values (POCP = photochemical ozone cre- ation potential) were determined which are listed below: Perchloroethylene 1 Trichloroet hylene 7 Dichloromethane 1 Methanol 10 Methyl acetate 3 lsopropyl alcohol 15 14.5. Environmental and Legal Aspects 33 3 Diacetone alcohol Acetone Ethyl acetate Ethanol C yclohexane Methoxypropyl acetate Isobutyl acetate Methylcyclohexane Isobutanol Methyl ethyl ketone Hexane Butyl acetate Propanol Toluene Butanol sec-Butanol 20 20 20 25 25 30 35 35 40 40 40 45 45 55 55 55 Ethyl glycol acetate Butyl glycol acetate Diethyl ether Ethoxypropyl acetate Tetrahydrofuran Ethyl glycol Butyl glycol Isophorone Methox ypropanol Diisobutyl ketone Ethoxypropanol p-X ylene 1.3-Diethylbenzene Tetramethylbenzene Trimethylbenzene Diethylmethylbenzene 60 60 60 65 70 15 75 80 80 80 85 90 95 110 120 120 In the TA Luft organic substances (including solvents) are divided into two groups of which each group is subdivided into three classes. The following concentration limits must not be exceeded in emissions: Non carcinogenic substances: Class I: Substances with a mass flow 2 0.1 kg/h: 20 mg/m3 Class I/: Substances with a mass flow 2 2 kg/h: 100 mg/m3 Class 111: Substances with a mass flow 2 3 kg/h: 150 mg/m3 Carcinogenic substances: Class I: Substances with a mass flow 2 0.5 g/h: 0.1 mg/m3 Class /I: Substances with a mass flow 2 5 g/h: 1 mg/m3 Class 111: Substances with a mass flow 2 25 kg/h: 5 mg/m3 If non-carcinogenic organic compounds of several classes are present, the mass concentration in the waste gas must not exceed 150 mg/m3 with a total mass flow 2 3 kg/h. The classes contain the following solvents (non carcinogenic): Cbss I. Aniline, 1 ,4-dioxane. nitrobenzene. phenol, 1,1.2,2-tetrachloroethane. tetrachloromethane, trichloromethane. furfurol. Cluss II. Butyl glycol, chlorobenzene, cyclohexanone. dimethylformamide, diisobutyl ketone, ethyl glycol, ethylbenzene. furfuryl alcohol, isopropylbenzene, carbon disulfide, methyl glycol, methyl acetate, methyl cyclohexanones, methyl formate, styrene, tetrachloroethylene, tetrahydro- furan. toluene, 1 .l.l-trichloroethane. trimethylbenzenes, xylenes. C1u.r.r 111. Acetone, alkyl alcohols, methyl ethyl ketone, butyl acetate, dibutyl ether, diethyl ether, diisopropyl ether, dimethyl ether, ethyl acetate, ethylene glycol. diacetone alcohol, methyl isobutyl ketone, N-methylpyrrolidone. paraffin hydrocarbons (except methane), pinenes. Organic substances not listed above should be allocated to the classes containing substances that they most closely resemble as regards their environmental effects. The toxicity, degradability, degradation products, and their odor intensity should be borne in mind. The degradation of solvents by microorganisms in water, wastewater, effluent, and in clarification plants differs. In Germany solvents have been therefore classified 314 14. Sohent.~ as non, weakly, slightly, moderately, or strongly water-polluting [14.140]. In general, the discharge of solvents into water and waterways should be avoided to prevent contamination of rivers and ground water. The majority of solvents in wastewater and treatment plants are degradable if handled properly [14.141]. Detailed investiga- tions have been carried out to assess the toxicity of solvents toward fish, which have been embodied OECD test standards [14.142], [14.143]. 14.5.2. Laws Concerning Dangerous Substances The EC directives and the wording of the dangerous substances directive are being continually updated. In order to assess the potential danger of a solvent the current wording of the directive should therefore be consulted. On the basis of the EC directives the Verordnung uber gefihrliche Stoffe, Gef- StoffV (Directive on Dangerous Substances) of August 26, 1986 was issued in Ger- many (Bundesgesetzblatt I, p. 1470) in the wording of June 5, 1991 (Bundesgesetz- blatt I, p. 1 - 1218). Classification criteria such as danger of explosion, fire promoting. highly flammable. readily flammable. flammable, highly toxic, toxic, harmful. corrosive, irritant, carcinogenic. reproduction toxic. and mutagenic are defined in this directive. Instructions are given concerning the packaging and labelling of substances and preparations. The directive also contains instructions on the han- dling of dangerous substances (protective measures, prohibition of use, official regulations) and on health monitoring (preventive medicine, health data file). Individual paragraphs deal with legisla- tion for the protection of young workers, pregnant women, and nursing mothers, and regulations governing trades, businesses, and working hours. Appendices I-VI include regulations concerning classification and identification; directives covering carcinogenic substances, aliphatic chlorinated hydrocarbons, lead and antifouling paints; provisions on working in rooms and containers; pre- scribed medical examinations; and a list of substances together with legally binding information on their labelling. The German Chemikaliengesetz, ChemG (Chemicals Law) was passed on Septem- ber 18, 1980 (Bundesgesetzblatt I, p. 171 8) and deals with protection against danger- ous substances. Newly developed substances must be registered with the authorities and subjected to toxicological testing. Similar regulations exist in other countries. Toxicological and ecotoxic data are also being compiled for chemicals that already exist and are listed in the European Inventory of Existing Chemical Substances (EINECS). The Toxic Substances Control Act (TSCA) in the United States has been effective since 1977 and is similar to the German Chemicals Law. The TSCA specifies that chemicals must be assessed as regards their risks and registered before production and use. The Technische Regeln fur Gefahrstoffe, TRGS (Technical Regulations for Dan- gerous Substances) specify safety, industrial medicine, hygiene, and ergonomic re- quirements for introducing and handling dangerous substances. [...]... ether trichloro ethene 111-77-3 107 -21-1 78-93-3 79-20-9 67-56-1 109 -86-4 1 10- 49-6 1 10- 12-3 108 -11-2 108 -10- 1 563-80-4 57-55-6 107 -87-9 1634-04-4 1 12-35-6 7 1-36-3 872-50-4 71-23-8 30136-13-1 109 -60-4 29387-86-8 57515-72-7 108 -32-7 688 1-94-3 127-18-4 2807-30-9 632-84-7 107 -98-2 108 -65-5 770-35-4 (4169-04-4 ' I ) ') No of isomers 78-92-2 105 -46-4 75-65-0 1 12-21-6 109 -99-9 873-94-9 1638-16-0 25498-49-1... 96-48-0 143-22-6 123-42-2 74-95- 3 60-29-7 1 11-46-6 96-22-0 108 -83-8 4039-63-8 108 -20-3 127-19-5 68-1 2-2 67-64-1 67-68-5 35884-42-5 25265-71-8 34590-94-8 106 -68-3 96-49-1 1 1 1-90-0 112-15-2 7737-40-8 1 10- 80-5 111-15-9 104 -76-7 103 -09-3 141-78-6 64- 1 7-5 122-25-4 78-83-1 1 10- 19-0 97-85-8 78-59-1 67-63-0 108 -21-4 109 -59-1 3944-36-3 1 10- 43-0 591-78-6 337 Table 21 (continued) Abbreviation Name CAS-NO... inwardly migrating solvents Mild true solvents (e.g., alcohols and glycol ethers), diluents, and non -solvents should be used for this 14.7.2 Solvents in Paint Removers Solvents used for paint removal are able to dissolve or considerably swell physically drying binders (e.g., vinyl chloride copolymers, cellulose nitrate, polyacrylates) and chemically cross-linked coatings (e.g., oil-based paints, dried alkyd... Important information and data on individual solvents are listed in the following tables: Table 3 5 Solubility parameters, dipole moments, and hydrogen bond parameters Table 16 Miscibility with water Table 17 Azeotropes of the most important solvents Table 18 Relationships between solubility parameter and surface tension Table 19 Gross calorific values Table 20 Standards for solvents and solvent tests... used in casting, rolling, and hot-spraying methods The correct choice of solvents serves to optimize the paint properties [14.200], [14.201] Solvents in High-Solids and Waterborne Paints In high-solids (low-solvent) paints, small amounts of auxiliary solvents are used to reduce the viscosity, as well as to optimize degassing and the flow properties [34.202] Butyl acetate and butanol are mainly used... Alcohols, glycol ethers, and glycol ether esters are most suitable for gravure and flexographic printing The volatility of the solvents must be adapted to the application process, the drying process, and the drying time during printing Solvents are rarely used in offset, letterpress, and typograhical printing, whereas rapidly evaporating solvents are employed in flexographic and gravure printing 323... solution is cooled and accordingly the more slowly the crystals form 14.7 Lfws 325 14.7.9 Solvents in Film Production Diethyl ether-ethanol mixtures are used as solvents in the production of cellulose nitrate films Acetone is most suitable for cellulose acetate or cellulose acetate butyrate films, and dichloromethane for cellulose triacetate films 14.7 .10 Solvents for Synthetic Fibers Solvents used for... and high boilers are used to produce a flawless surface Oven-drying paints, stoving enamels, and coil coatings are applied at relatively high temperature and contain a large amount of high boilers and only a small amount of readily volatile solvents, if at all, because they may cause the paint to “boil” during stoving The nature of the solvents in the mixture also depends on the type of binder In order... propylene carbonate, and N-methylpyrrolidone) in combination with alcohols and aromatics, or consist of aqueous, frequently alkaline or acidic systems 14.7.3 Solvents in Printing Inks Solvents in printing inks must readily dissolve the binder or resin and must not attack the printing rollers [14.238] Acidic or sulfur-containing solvents must not be used with copper rollers Aliphatic and aromatic hydrocarbons... drying temperature, and drying time of the paint The solvent mixture in a paint that undergoes physical drying at room temperature contains ca 45 O low boilers, ca 45 % medium boilers, and ca 10% n / high boilers True solvents and latent solvents are present in such a ratio that the paint dries to give a clear film without haze Low boilers accelerate drying, whereas medium boilers and high boilers are . inwardly migrating solvents. Mild true solvents (e.g., alcohols and glycol ethers), diluents, and non -solvents should be used for this. 14.7.2. Solvents in Paint Removers Solvents used for. of solvents into water and waterways should be avoided to prevent contamination of rivers and ground water. The majority of solvents in wastewater and treatment plants are degradable if handled. Oven-drying paints, stoving enamels, and coil coatings are applied at relatively high temperature and contain a large amount of high boilers and only a small amount of readily volatile solvents,