TECHNICAL TIP HANDLING PROCEDURES FOR EPOXY ADHESIVES

Transcription

1 1. Introduction These notes are based on practical experience and are intended to discuss the more commonly asked questions about cold epoxy adhesives and how they should be handled to achieve best results. Safety is mentioned, however it is crucial that this is also assessed locally taking full consideration of: Material Safety Data Sheet (MSDS) of the epoxy adhesive Local work environment Why choose a one component epoxy adhesive? One component cold syringe packed epoxy adhesives are widely used in many high volume production environments because they offer a number of practical benefits. The materials are manufactured under vacuum and packaged into syringes or cartridges under controlled conditions, before storing at sub-zero temperatures. This style of product offers considerable practical benefits. These include eliminating the need for mixing, easy automated dispensing, reduced operator contact, less cleaning, more consistent air-free material. A few simple handling precautions are recommended to ensure that the material is kept in optimum condition during shipping, storage and use. 2. Health and Safety 2.1. Material Safety Data Sheet (MSDS) Emerson & Cuming provides MSDS for all epoxy adhesives. The MSDS should always be reviewed prior to use of the material by anyone that may come into contact with it Safe Handling It is important that users are familiar with the safety information on the MSDS. Epoxy adhesives have widespread & successful use throughout many industries, however, as with all industrial chemicals we strongly recommend that operator exposure is controlled. ALL epoxy resin systems have possible hazards and avoidance of these hazards through proper control is the best solution. Potential hazards of epoxies are: skin sensitization (after prolonged unprotected exposure) dermatitis (after prolonged unprotected exposure) skin and eye irritation upon contact irritating vapors when curing possibility of exothermal reaction when curing large masses Page 1 of 7

2 Page 2 of 7 The syringe packages that we supply help to minimize skin contact, however it is still important that spillage is dealt with appropriately & operator contact controlled as per the MSDS. In addition to familiarity with the MSDS, operators should be familiar with the recommended protective/preventive measures that may be obtained through a variety of sources: read the label on the syringe speak to your supervisor follow good personal hygiene: wash hands, use personal protective equipment (PPE) training provided by qualified E&C personnel 3. Supply Chain 3.1. Transportation All shipments will comply with all local and national regulations. For materials that must be temperature controlled, the standard packaging configuration consists of an outer corrugated box with an inner insulating layer containing dry ice at about -80 C. The cooler configuration ensures that the product chamber gets no colder than -30 to -35 C, which means that the product should not reach its freeze point and therefore should not develop freeze/thaw voids. Dry ice packages remain cool for up to 4 days. E&C prefer to ship dry ice packages on Mondays, Tuesdays or Wednesdays, thus ensuring that packages do not arrive and sit over the weekend before transfer to cold storage. Paperwork included with shipment: packing lists / Certificate of Compliance and any required Certificate of Analysis, will be included with all shipments inside the shipment box Inspection of Shipment Packages should be inspected immediately upon receipt. Our aim is to supply all goods in perfect condition. If they are damaged in transit for any reason, we are keen to identify and correct the cause. In the unlikely event that you experience a problem, please make us aware as soon as possible. If a package is damaged, please note this on the delivery note, as we may need to claim against our carrier. Photographs of the problem are always appreciated, as they will help in identifying the cause. Europe North America Asia-Pacific Nijverheidsstraat 7 46 Manning Road 100 Kaneda, Atsugi-shi B-2260 Westerlo Billerica, MA Kanagawa-ken, Belgium % Japan % +(32)-(0) % (978) % (81) Fax: +(32)-(0) Fax: (978) Fax: (81) ANY OTHER USE. These materials are not designed or manufactured for use in implantation in the human body. National Starch has not performed clinical testing of these materials for implantation. National Starch has neither sought, nor received, approval from the FDA for the use of these materials in implantation in the human body. No representative of ours has any authority to waive or change the foregoing provisions but, subject to such provisions, our engineers are available to assist purchasers in adapting our products to their needs and to the circumstances prevailing in their business. Nothing contained herein shall be construed to imply the non-existence of any relevant patents or to constitute a permission, inducement or recommendation to practice any invention covered by any patent, without authority from the owner of this patent. We also expect purchasers to use our products in accordance with the guiding principles of the Chemical Manufacturers Association s Responsible Care program National Starch & Chemical Company

3 Special attention is needed for products that are shipped with dry ice. If upon receipt no dry ice is visible, E&C should be informed and the condition of the adhesive checked prior to use. Damaged packages are more likely to loose the dry ice. Any physical damage to the box should therefore be noted on the delivery note and the contents checked immediately. Please do not return material directly to us as this causes problems with tracability & investigation, if necessary we will arrange collection. 4. Storage Syringes that are shipped with dry ice should be transferred directly from the dry ice to the recommended storage temperature without delays. This recommended storage temperature can be found on the label of the adhesive. For best results, store in original, tightly covered containers. Storage in cool, clean and dry areas are recommended. If these recommended storage conditions are not respected, this will have a dramatic effect on the usable shelf and work life of the one component epoxy adhesive (see also paragraph 5.4.): e.g. freezer failure: monitoring freezer temperature is recommended. Safety : Dry ice (solid carbon dioxide) is extremely cold (-80 C) and has the potential to cause freeze burns. Suitable protective gloves should be worn. Unpack in a wellventilated area. 5. Instructions for use 5.1. Surface preparation Epoxy based adhesives generally have excellent adhesion to clean, oxide-free surfaces. They cannot overcome high levels of surface contamination such as silicones, greases, heavy oxidation, dirt etc. High levels of ionic contamination on surfaces may also promote corrosion that will be detrimental to the long-term reliability of the adhesive joint. Any changes to the cleaning materials or process used should be checked for compatibility Freeze/Thaw voids Emerson & Cuming takes all necessary precautions with packaging configurations to avoid Freeze/Thaw void (FTV) formation. FTVs form when a syringe is frozen and then exposed to higher temperatures. This causes the syringe to snap away from the material, entrapping air when the adhesive is brought to room temperature. This is illustrated below. Page 3 of 7

4 Page 4 of 7 Syringe Wall Frozen Adhesive Freeze/ Thaw Voids Air Gap before freezing after freeze/thaw snap after thaw 5.3. Conditioning procedure To avoid the formation of FTV as much as possible, the following guidelines should be followed: handle the syringes by using gloves handle the syringes by the end or bags by the corner (e.g. even a warm hand holding a cold syringe can sometimes cause formation of freeze/thaw voids) thaw the syringes with the dispensing tip down at room temperature. This will reduce the risk of air voids causing inconsistent dispensing. allow the material to reach room temperature before use. Remove any moisture (condensation) on the packages prior to opening. do not attempt to thaw by applying additional heat Typical conditioning times for different package sizes are shown below (at room temperature, for products stored at 20 C to 0 C): Package size Recommended conditioning time at 25 C 10 cc minutes 30 cc 2 hours 55 cc 2 hours 6 ounce 3 hours Europe North America Asia-Pacific Nijverheidsstraat 7 46 Manning Road 100 Kaneda, Atsugi-shi B-2260 Westerlo Billerica, MA Kanagawa-ken, Belgium % Japan % +(32)-(0) % (978) % (81) Fax: +(32)-(0) Fax: (978) Fax: (81) ANY OTHER USE. These materials are not designed or manufactured for use in implantation in the human body. National Starch has not performed clinical testing of these materials for implantation. National Starch has neither sought, nor received, approval from the FDA for the use of these materials in implantation in the human body. No representative of ours has any authority to waive or change the foregoing provisions but, subject to such provisions, our engineers are available to assist purchasers in adapting our products to their needs and to the circumstances prevailing in their business. Nothing contained herein shall be construed to imply the non-existence of any relevant patents or to constitute a permission, inducement or recommendation to practice any invention covered by any patent, without authority from the owner of this patent. We also expect purchasers to use our products in accordance with the guiding principles of the Chemical Manufacturers Association s Responsible Care program National Starch & Chemical Company

5 As an example two conditioning graphs are given for products stored in different syringes at respectively 20 and 0 C. Products stored at -20 C Elaps ed time, minutes Lab ambient 30 cc 55 cc 6 o z Products stored at 0 C Elapsed time, minutes Lab ambient 55cc and 30cc 6 oz Important to remark is that due to the identical internal diameter of the syringes of respectively 30cc and 55cc, their conditioning time will also be similar. It is extremely important that the adhesive is fully conditioned to room temperature before use to avoid moisture problems and to obtain a stable viscosity Adhesive work life It s important to note that the work life of a material is quite dependent on the individual application. One component materials are formulated with properties that give sufficient stability to allow use at ambient temperature, whilst they are reactive enough to cure quickly at elevated temperatures. However exposure to room temperature or elevated temperatures can have a dramatic effect on the work life of these one component epoxy adhesives. This is shown in the next graph where, as an example, the viscosity changes at different temperatures are given as a function of the time. At the recommended storage temperature the viscosity of the epoxy adhesive will remain stable (< 25 % increase in viscosity). At room temperature the viscosity already increased significantly, reducing the work life to approximately one day. At higher temperatures the increase in viscosity is dramatic. Page 5 of 7

6 Page 6 of 7 This graph clearly shows the importance of the storage conditions on the work life as mentioned already in paragraph 4. Adhesive working life at different temperatures Viscosity (mpas) storage T T = RT T = 40 C Time (hours) 5.5. Dispensing of the adhesive During dispensing any temperature change in the clean room can lead to viscosity changes of the adhesive, as is shown in the next graph. Simple air-over dispense equipment will not compensate for this slight change in viscosity and the dispensed volume may change. It is possible that, without appropriate adhesive temperature control, the dispensing parameters will need some adjustment throughout the day. Viscosity changes in function of the temperature 100 Viscosity change (%) E T = 20 C T = 22.5 C T = 25 C T = 27.5 C T = 30 C Therefore for optimal performance a consistent dispense temperature is recommended. This will reduce the effect of a potential temperature change between storage place and cleaning room. It will also compensate for possible temperature variations in the clean room during the day whilst dispensing. Europe North America Asia-Pacific Nijverheidsstraat 7 46 Manning Road 100 Kaneda, Atsugi-shi B-2260 Westerlo Billerica, MA Kanagawa-ken, Belgium % Japan % +(32)-(0) % (978) % (81) Fax: +(32)-(0) Fax: (978) Fax: (81) ANY OTHER USE. These materials are not designed or manufactured for use in implantation in the human body. National Starch has not performed clinical testing of these materials for implantation. National Starch has neither sought, nor received, approval from the FDA for the use of these materials in implantation in the human body. No representative of ours has any authority to waive or change the foregoing provisions but, subject to such provisions, our engineers are available to assist purchasers in adapting our products to their needs and to the circumstances prevailing in their business. Nothing contained herein shall be construed to imply the non-existence of any relevant patents or to constitute a permission, inducement or recommendation to practice any invention covered by any patent, without authority from the owner of this patent. We also expect purchasers to use our products in accordance with the guiding principles of the Chemical Manufacturers Association s Responsible Care program National Starch & Chemical Company

7 5.6. Epoxy clean up Spoiled non-cured epoxies should best be cleaned up as soon as possible. A simple clean wipe is the most effective method and therefore strongly recommended. Cured epoxy resins are very heat and chemically resistant and difficult to remove. The safest method for removing these materials is by heating to soften them and by mechanical scraping i.e. heat gun and paint scraper. 6. Key Words Freeze-Thaw Voids = air-voids that are formed in syringes because of differences in thermal expansion coefficient between the plastic syringe and the adhesive during thermal cycling. Shelf Life = The length of time from date of manufacture during which a product can be expected to remain in good useable conditions when properly shipped and stored. Work Life (for a frozen adhesive) = The time period of reliably useful life after conditioning to room temperature. Application specific. Conditioning = process whereby cold syringes are brought to room temperature prior to use for consistent dispense performance. E-30/04/ L. Mattheus Page 7 of 7