Unit 2 / 13 Stanton Road Seven Hills, NSW 2147 Australia Effective:

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1 Unit 2 / 13 Stanton Road Seven Hills, NSW 2147 Australia Effective: CAYTUR 21 DA CAYTUR 21 DA is a blocked, delayed-action diamine curative for use primarily with urethane elastomer prepolymers based on toluene diisocyanate and polyether polyols. It consists of a complex of methylene dianiline (MDA) and sodium chloride, dispersed in dioctyl adipate. At room temperature, it reacts very slowly with terminal isocyanate groups. However, when heated to C ( F), the salt complex unblocks and the freed MDA rapidly cures the urethane elastomer. Caytur DA and Caytur 21 are similar to each other with respect to the long term mix stability and pot life. Caytur 21 DA and Caytur 21 differ from each other in the plasticizer used to disperse the salt complex. Caytur 21 DA uses DOA (dioctyl adipate), a more benign plasticizer, whereas Caytur 21 uses DOP (dioctyl phthalate). They also differ in active solids content. Caytur 21 DA has higher solids content (60% active solids) compared to Caytur 21 (50% active solids) leading to improved physical properties. However, to obtain similar properties as Caytur 21, more plasticizer (DOA) may be added to reduce the active solids content. CAYTUR 21 DA provides a desirable combination of long working life and fast cures. It yields vulcanizates with physical properties similar to those of vulcanizates cured with MBCA (4,4'-methylene-bis-[2-chloroaniline]), and with outstanding dynamic properties. Suitable grades of ADIPRENE urethane rubber are available to provide a full range of hardness from 79A to 62D, using CAYTUR 21 DA as the curative. A low viscosity liquid, CAYTUR 21 DA is suitable for use with conventional processing techniques such as: open casting; transfer, compression or liquid injection molding; and rotational casting. In addition, it is uniquely suitable for such specialty applications as belt or fabric coatings and adhesives because of its long, controllable working life. The information contained herein relates to a specific Chemtura product and its use, and is based on information available as of the date hereof. Additional information relating to the product can be obtained from the pertinent Material Safety Data Sheets. NOTHING IN THIS TECHNICAL DATA SHEET SHALL BE CONSTRUED TO CONSTITUE A REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, REGARDING THE PRODUCTS CHARACTERTICS, USE, QUALITY, SAFETY, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Nothing contained herein shall constitute permission or recommendation to practice any intellectual property without the permission of the owner. Chemtura Copyright and the 2007 Chemtura Chemtura logo Corporation. are trademarks All rights of Chemtura reserved Corporation Page or 1 one of its subsidiaries. Copyright 2007 Chemtura Corporation. All rights reserved.

2 (These data are typical values, presented to describe CAYTUR 21 DA; they are not intended to serve as a specification.) Chemical Composition Approximately 60% dispersion of methylene dianiline/sodium chloride complex in dioctyl adipate (DOA) Amino Nitrogen (A.N.) % Equivalent Weight (E.W.) * 25 C...White liquid free from contamination Odour...Faint amine Decomposition Temperature, When mixed with polymer, C ( F) ( ) Alone in air, C ( F) (320) Viscosity at 30 C...Approximate value: 1425 (Brookfield Viscometer Model RVT,spindle No. 5, speed 5 rpm) Moisture Content, % Settling Characteristics...Slow separation redisperses readily with agitation or rolling. Always mix thoroughly before using. Particle Size, µm (microns)...4 max (4 max) Free MDA * E.W. is calculated by using the Amino Nitrogen (A.N.) number on the COA and the following formula: E.W.= (14.007/A.N)x100. Toxicity and Handling Precautions Methylene dianiline (MDA), the active ingredient of CAYTUR 21 DA, has been shown to produce cirrhosis of the liver and kidney damage in rats and dogs in experimental studies. It is known to have caused hepatitis in industrial workers in the early 1970's. MDA is considered to be a potential human carcinogen and it has been added to the ACGIH Appendix A2. The ACGIH has established a TLV for MDA of 0.1 ppm for an 8-hour TWA exposure. Since MDA is complexed with sodium chloride and dispersed in dioctyl plithalate, dust exposure has been eliminated and, at recommended handling and processing temperatures, vapour exposure is minimized. CAYTUR 21 DA can cause allergic skin reactions and eye irritation. The use of protective clothing and gloves is recommended. Copyright 2007 Chemtura Corporation. All rights reserved Page 2

3 Storage Stability The storage stability of Caytur 21 DA appears to be unlimited at room temperature, and at least several months at 50 C (122 F). However it is recommended that Caytur 21 DA be stored at room temperature. Storage at room temperature for prolonged periods does not affect the performance of the product. Caytur 21 DA needs to be rolled after prolonged storage to provide adequate remixing to insure, homogeneity prior to use. Storage or handling above 50 C (122 F) is not recommended since the complex may dissociate and reduce working life of the polymer/curative mix. Disposal CAYTUR 21 DA is not presently regulated under the Resource Conservation and Recovery Act (RCRA), as of the Federal Register of May 19, However, disposal should be made in an appropriate manner. CAYTUR 21 DA can be disposed of by reacting it with isocyanate terminated polymers containing excess isocyanate groups. It may be incinerated in a halogen type incinerator or buried in an approved landfill designed for chemical wastes. Disposal must be in accordance with local, state and federal regulations. ADIPRENE L URETHANE RUBBER Uncured ADIPRENE L urethane rubbers contain small quantities of free toluene diisocyanate (TDI), which is known to cause severe irritation to the eyes, skin and mucous membranes. Avoid contact with eyes, skin and clothing, and wash thoroughly after handling. Avoid breathing vapour. Use only with adequate ventilation. In the USA, employee exposure to toluene diisocyanate is regulated by the U.S. Department of Labour (OSHA); exposure shall at no time exceed 0.02 parts TDI per million, by volume 3 (refer to 29 C.F.R , Air Contaminants). For additional information on potential hazards and handling precautions for ADIPRENE L, see bulletin AP- I 10.1, "Toxicity and Safe Handling of ADIPRENE ". OTHER COMPOUNDING INGREDIENTS 4,4'-Methylene-bis [2-chloroaniline] (referred to in this bulletin as MBCA) may cause cancer, based on tests with laboratory animals. It may also cause cyanosis (reduction in the oxygen carrying capacity of the blood). It can be absorbed through the skin, so skin contact should be avoided. Also avoid breathing vapours. In case of contact, wash skin with soap and plenty of water. Flush eyes with plenty of water for at least 15 minutes, and call a physician. Dispose of contaminated clothing. If vapours are inhaled, take exposed person to fresh air. Give oxygen or artificial respiration if needed, and call a physician. For additional information on handling precautions and possible health hazards, contact the supplier and read product labels; also, consult appropriate regulatory agencies. Pigments, extenders, solvents, and other materials that may be used with ADIPRENE L urethane rubber in the manufacture of finished products may also present hazards in handling and use. Before proceeding with any compounding or processing work, consult and follow label directions and handling precautions from suppliers of all ingredients. Copyright 2007 Chemtura Corporation. All rights reserved Page 3

4 SPECIAL NOTE - Except as otherwise provided by law outside the USA, the following information should be noted: The information contained herein is correct to the best of our knowledge. Your attention is directed to the pertinent Material Safety Data Sheets for the products mentioned herein. All sales are subject to Chemtura s standard terms and conditions of sale, copies of which are available on request and are printed on the reverse of Chemtura invoices. Except as expressly provided in Chemtura s standard terms and conditions of sale, no warranty, express or implied, including warranties of merchantability or fitness for a particular purpose, is made with respect to the products described herein. Nothing contained herein shall constitute permission or recommendation to practice any invention covered by a patent without a license from the owner of the patent. COMPOUNDING AND CURING CHARACTERISTICS Due to the blocked nature of the curative, mixtures of CAYTUR 21 DA and prepolymer must be heated to affect a cure. The time necessary to cure a given part depends upon the time for the innermost section to reach the unblocking temperature of 100 to 150 C (212 to 302 F). Once this takes place, the mixture cures rapidly due to the speed of reaction between free MDA and isocyanate. Films only a fraction of a millimetre (a few mils) thick, as used in adhesives, are cured in seconds, while 1.9 min (75 mil) thick test slabs are cured in 2 to 10 minutes, depending on the temperature and polymer used. This rapid cure may require the use of lower mold or mix temperature to prevent premature gelation during filling of molds. POLYMER SELECTION The preferred grades of ADIPRENE urethane rubber for use with CAYTUR 21 DA are ADIPRENE L 42, L 83, L 300, L 700, L167, L 367, L 767, and L 315. Table I compares the hardness and stress-strain properties of these ADIPRENE L167 prepolymer cured with CAYTUR 21 and CAYTUR 21 DA For comparison purposes, the amount of curative used in all cases was about 95% of the theoretical stoichiometric amount. Note: Vulcanizate physical properties shown in Table I (and subsequent tables) were measured on compression-molded test slabs and pellets. Sample size and thickness was as specified in the appropriate ASTM test. Copyright 2007 Chemtura Corporation. All rights reserved Page 4

5 TABLE I COMPARISON OF CAYTUR 21 DA VS. CAYTUR 21 Material: Adiprene Caytur 21 Caytur 21-DA Caytur 21-DA L167 (50% solids) (50% solids) (60% solids) Hardness Shore A D Tensile, psi D Elongation, % D % Mod psi D % Mod psi D Split Tear, lb./in D Trouser Tear, lb/in D Die C Tear, lb./in D Bashore Rebound, % D Compression Set % (Method B) 22 D395-B F (70 C) Compressive Mod., psi Third Cycle [aged] 5% 10% 15% 20% 25% D Specific Gravity D Polymers of High NCO Content Free diisocyanate has a deactivating effect on the unblocking of CAYTUR 21 DA. Thus, urethane polymers of high NCO content, such as ADIPRENE L 315 and L 767, cure more slowly than polymers of lower NCO content (at the same cure temperature). Thin sections (up to about 6.4 min (0.25 in) thick) generally cure without difficulty, but thicker sections often develop cracks or voids during cure because the centre of the piece does not warm up to the unblocking temperature as quickly as does the outer section. One way to partially overcome the deactivating effect of free isocyanate is to increase cure temperature. In thick sections, however, this approach merely aggravates the temperature and cure rate differential between the outer edges and the centre of the piece. The preferred method for obtaining a satisfactory cure in thick sections with polymers of high NCO content is to add a catalyst, such as glycerol, which reduces the unblocking temperature Of CAYTUR 2 1. For additional information, see Catalysis. Techniques for processing CAYTUR 21 DA with ADIPRENE urethane rubbers having high NCO content are discussed on page 20. Copyright 2007 Chemtura Corporation. All rights reserved Page 5

6 CATALYSIS Polar compounds such as glycerol and urea may be combined with CAYTUR 21 DA urethane curative to reduce cure time or temperature and to facilitate curing of thick parts, particularly with high hardness systems such as ADIPRENE L 315 (62D). The role of these catalysts is to reduce the unblocking temperature of the methylene dianiline-sodium chloride complex, not to increase the inherently rapid reaction between MDA and isocyanate groups. Urea or glycerol catalysts are best incorporated by prior addition to CAYTUR 21 DA. Glycerol is preferred over urea, since it readily disperses into CAYTUR 21 DA; to use urea, one must either disperse it in DOA before adding it to CAYTUR 21 DA, or ball-mill powdered urea directly into CAYTUR 21 DA. Apart from its ease of addition, glycerol is unique among polar catalysts in that it does not cause either thickening or break-down of the CAYTUR 21 DA dispersion. For example, substitution of other polyhydroxy compounds, such as diethylene glycol, for glycerol causes an unacceptable thickening of the mixture on storage. The catalytic activity of blends of glycerol and CAYTUR 21 DA does not change on storage. Vulcanizate properties are unchanged. COLOURED VULCANIZATES Vulcanizates of ADIPRENE urethane rubber are often coloured for aesthetic or identification purposes. Using one brand of commercially available yellow, blue, and red pigment dispersions, we found that pigmented compositions cured with CAYTUR 21 DA exhibit lighter tints or pastel shades of the colours, rather than the deeper, brighter shades characteristic of vulcanizates cured with MBCA. This difference is due to the white, opaque nature of vulcanizates cured with CAYTUR 21 DA (giving somewhat the effect of the white pigment), in contrast to the translucency of vulcanizates cured with MBCA. The difference in appearance can be minimized by adding extra pigment dispersion when using CAYTUR 21. The choice of carrier for the pigment is important. Plasticizers are generally satisfactory as carriers for the pigment. PROCESSING CAYTUR 21 DA curing agent can be processed satisfactorily using batch mixing techniques and automatic mixing equipment which are typical for processing liquid urethane elastomers. MIXING Batch Mixing ADIPRENE L urethane rubber should be warmed to C ( F), depending on the polymer, and then degassed. Caytur 21 DA can be kept at room temperature or warmed to 50 C (122 F). Prior to use, the container of Caytur 21 DA should be rolled until the container bottom shows no sediment after being inspected with a rod, in order to ensure that the dispersion is uniform (usually, 24 hours of rolling is required). Care must be taken not to overheat (above 50C (122 0 F)) even a portion of the CAYTUR 21 DA, because the complex may prematurely decompose. Oven heating is most satisfactory for batch processing, if required. The procedure sometimes used with MBCA-i.e., heating for a short time on a hot Copyright 2007 Chemtura Corporation. All rights reserved Page 6

7 plate-must not be followed with CAYTUR 21 DA because local overheating causes local decomposition, resulting in shorter working life of the polymer/curing agent mix. Since CAYTUR 21 DA is dispersion, it requires thorough agitation to achieve a satisfactory Mix. CAYTUR 21 DA should be added to the warm polymer and thoroughly blended in with a motor-driven agitator. Mixing should be done gently and carefully to avoid entrapping air. The mixed compound may then be poured into preheated molds and cured as usual. Soft and sticky areas on the surface of the vulcanizate indicate poor mixing. If required, the mixture Of CAYTUR 21 DA and prepolymer can be conventionally degassed at 60 to 65 C (140 F to 149 F). Minor modifications in mixing temperatures may be made to suit individual applications, but working life can be expected to decrease rapidly as the mixing temperature is increased. At 85 C (185 F), the working life of a mix of ADIPRENE L 767 and CAYTUR 21 DA is less than two minutes as judged by pourability. Machine Mixings Suggested temperatures for machine mixing are: 70 to 95 C (158 to 203 F) for the polymer and 20 to 50 C (68 to 122 F) for CAYTUR 21 DA. The polymer should be degassed. A mix temperature of about 70 C (158 F) provides ample working life for most applications. As noted earlier, the chemical stability Of CAYTUR 21 DA decreases substantially above 60 C (140 F), so it should not be processed above that temperature. Some machine modifications may be required when handling CAYTUR 21 DA instead of MBCA. For a given polymer, approximately 80% more volume Of CAYTUR 21 DA is required than of MBCA, so correspondingly larger metering pumps or pistons will be required. Also, it is imperative that reservoirs for CAYTUR 21 DA be equipped with low wattage heaters and a good agitator to prevent settling, local overheating and decomposition. Due to the tendency of the dispersion to settle, daily drainage of pumps, lines and reservoirs is recommended. Circulating systems may prove beneficial. Occasionally, short working life may be observed with machine mixed compositions. This can usually be traced to slight leakage of the polyol used to lubricate the seal of the mixing head. Changing the lubricant to one that does not contain hydroxyl groups (e.g., dioctyl phthalate) should eliminate the problem. Processing Urethanes of High NCO Content The free TDI present in high NCO polymers such as ADIPRENE L-315 tends to deactivate CAYTUR 21 DA, resulting in cracking and fissuring of large parts (50 to 100 min (2 to 4 in) thick). This problem is best overcome by incorporating a polar catalyst, such as glycerol, into the CAYTUR 21 DA (see Catalysis, ). In addition, the following factors will aid in the production of mar-free thick parts on a routine basis. Copyright 2007 Chemtura Corporation. All rights reserved Page 7

8 Use as high a mix temperature as practical, consistent with the required working life. We find that when using glycerol at the 0.3 phr level and maintaining the temperature of the mixed curative/prepolymer stream exiting the mixing head at 60 C (140 F), a six minute working life is obtained with ADIPRENE L-315. Excellent parts as thick as 100 min (4 in) have been produced. Place the filled mold in an oven or press as soon as possible. Mixed polymer held at mix temperatures for long periods tends to deactivate and will result in cracks and fissures. Increasing the speed of the agitator and/or reducing throughput of the mixing machine will improve the mixing efficiency and, therefore, the quality of the molding. MOLDING Compositions containing CAYTUR 21 DA curing agent can be molded by all of the techniques which are used for compositions cured with MBCA, such as casting and gel/compression molding. Conventional mold materials and mold release agents are satisfactory. Compositions containing CAYTUR 21 DA are especially well adapted, because of their long working life, to two molding methods in which MBCA cannot be used readily: liquid injection molding (LIM) and rotational casting. These are discussed in the following sections. Mixing and Mold Filling ADIPRENE L polymer and CAYTUR 21 DA curing agent are mixed at room temperature or slightly above, using an efficient mixer. Material so mixed and protected from atmospheric moisture will be thixotropic, though workable, for a number of hours. It may be necessary to vacuum degas for critical applications. The most bubble-free moldings are made from mixed materials delivered from an automatic mixing machine. Since delivery temperatures from such machines are usually above room temperature, working life of the mix may be shortened somewhat. However, at temperatures up to 70 C (158 F), working life should still be more than sufficient to allow multiple mold filling. Molding Conditions Generally, each molding application and each composition requires its own set of molding conditions. Good results have been obtained by rotating for 10 to 15 minutes at oven temperatures of 190 to 204 C (375 to 400 F). Shorter times or lower temperatures yield moldings which are poorly cured and difficult to demold. Higher temperatures can cause discoloration and, possibly, decomposition of the urethane. Rotational speeds of 5 rev/min on the major axis and 3 to 7 rev/min on the minor axis have been found satisfactory. Rotational speeds outside these ranges will usually result in uneven filling. Copyright 2007 Chemtura Corporation. All rights reserved Page 8

9 Shrinkage The normal linear shrinkage of parts of ADIPRENE cured with CAYTUR 21/CAYTUR 21 DA is 1 to 2 % in all molding methods. Shrinkage is primarily affected by the temperature of the gelling mass, and will therefore increase as the cure temperature or the exotherm temperature increases. Where molding tolerances must be held within close limits, shrinkage must be taken into account in mold dimensions - i.e., they should be oversize. The molded part may be expected to shrink inward from the walls of a containing mold and inward against an insert within the mold. If an insert is to be removed, it should be done as soon as the part can be demolded, before shrinkage occurs. Measurement of shrinkage depends upon the moisture content of the air and the length of time the part is exposed to the air. A part measured immediately after removal from the mold will appear to show more shrinkage than the same part measured two days later, if the humidity is high, since the part will have expanded slightly during exposure to the air. For consistent results, shrinkage should be determined immediately after the part has been demolded and cooled to room temperature. For design purposes, measure shrinkage after equilibration with the atmosphere. NOTES ON TEST PROCEDURES (Test temperature is 24 C (75 F) except where specified otherwise) Test Method Abrasion Resistance, NBS ASTM D1630, National Bureau of Standards Abrader Compression Set ASTM D395, Method B (Type I pellets, 25% deflection) Dynamic Properties Rheovibron Dynamic Tester Dynamic Modulus Loss Tangent Copyright 2007 Chemtura Corporation. All rights reserved Page 9

10 Electrical Properties: Dielectric Constant Dielectric Strength Power Factor Volume Resistivity Flex Life Hardness, Durometer A or D Properties after Heat-Aging Properties after Immersion in Fluids Stress-Strain Properties 100% and 300% Modulus Tensile Strength Elongation at Break Shrinkage, Linear Specific Gravity Tear Strength, Split Graves Torsional Modulus, Clash-Berg Viscosity Volume Change In Fluids ASTM D150 ASTM D149 ASTM D150 ASTM D257 ASTM D1052 ASTM D2240 ASTM D573 ASTM D471 ASTM D412, pulled at 8.5 mm/ s [20 in/ Accurate measurement of a 254 mm x 12.7 min x 12.7 mm (10 in x 0.5 in x 0.5 in) bar after heat cure ASTM D792 ASTM D470 ASTM D624, Die ASTM D1043 Brookfield ASTM D471 Mat Copyright 2007 Chemtura Corporation. All rights reserved Page 10