Weld-On 28 is a three-component, medium syrupy, clear, reactive acrylic cement. It polymerizes at room temperature forming high strength joints within a few hours. The bonded joint retains high strength and resists the effects of weathering, but may exhibit slight yellowing in especially harsh conditions. Where retention of clarity is required, Weld-On 40 is recommended.
Weld-On 28 is formulated for bonding acrylics, including cell cast, continuous cast, extruded, cross-linked and molded parts. It also bonds acrylics (PMMA) to polyester (PET), cellulose acetate butyrate (CAB), polystyrene and other materials.
Weld-On 28 is recommended for use as a high strength structural adhesive for bonding acrylics and other plastics. It has many applications and may be used for bonding acrylic to fabric-acrylic impregnates used in aircraft canopy construction. May also be used for laminating and wet lay-up work. This product meets Military Spec A-8576C Type II.
This product must be shipped via a ground service.
Typical Bond Strength†
† Substrate thickness: 0.25 inch (0.64 cm). Bond area: 1.0 in² (6.45 cm²). Ultimate Bond Strength is defined as strength achieved after 24-hour room temperature cure.
Adhesive Properties and Characteristics @ 73°F (23°C)
Directions for Use
Mixing: Before making final mixture, bring Component A to room temperature. CAUTION: Never mix Component B and C directly. (A violent reaction will occur). Per 4 fluid ounces of Component A, add 2.4 gram capsules of Component B. Stir until completely dissolved. Then add 5 cc vial of Component C and stir slowly and evenly to prevent excess air from entering into mixture.
Pot Life: When mixed, pot life at 75ºF (24ºC) is approximately 18 minutes. If base cement is above 85ºF (29ºC), pre-cool to 75ºF (24ºC) before mixing. Note: Shorter shelf life may result where larger masses are used and when temperature of base resin is above 75ºF (24ºC).
Surface Preparation: Surfaces to be joined should fit accurately without forcing. It should not be necessary to flex either piece more than a few thousandths of an inch to achieve complete contact. Surfaces should be sanded with 240 to 400 grit sandpaper before bonding.
Preliminary Annealing: To prevent crazing during bonding, acrylic should be annealed following machining and forming. Joint should be made as soon as possible after annealing. The time between annealing and bonding should not exceed 24 hours. (See Rohm and Haas Bulletin on Annealing Schedules).
Making The Joint: Apply cement with suitable applicator to one or both surfaces and assemble immediately. If plastic masking tapes are used, avoid contact of cement with adhesive side of tape. Apply just enough pressure to remove air bubbles. Do not squeeze parts so hard as to force cement out of joint, or a dry joint could result. If possible cover joint with cellophane to prevent inhibition of cure air.
Cure Time: Usually joints are hard enough for handling in 2 hours at room temperature. Machining may be done after 4 hours. We recommend where possible, a 24-hour cure before machining. For maximum strength, the joint should be cured for 4 hours at 158ºF (70ºC), preferably within 24 hours after assembly.
One year in tightly sealed containers stored in a cool 50° – 80°F (10° – 27°C) dry place. Storage near the ceiling in non air-conditioned warehouses is not recommended. Shelf life is reduced at higher temperatures and enhanced at lower temperatures. Keep away from sources of heat, open flame, sparks and sunlight. The date code of manufacture is stamped on the bottom of the container.
Safety and Environmental Precautions
This product is considered a hazardous material. In conformance with the Federal Hazardous Substance Labeling Act, the following hazards and precautions are given. Purchasers who may re-package this product must also conform to all local, state and federal labeling, safety and other regulations. There is no measurable VOC emission.
WARNING! FLAMMABLE. VAPOR HARMFUL. MAY BE HARMFUL IF SWALLOWED. MAY IRRITATE SKIN OR EYES.
Keep out of reach of children. Do not take internally. Keep away from heat, spark, open flame and other sources of ignition. Keep container closed when not in use. Store away from direct sunlight in a cool 50° F – 80° F (10° C – 27° C) dry place. Use only in adequate ventilation. Avoid breathing of vapors. Atmospheric levels should be maintained below established exposure limit values. See Sections II and VIII of Material Safety Data Sheet. If airborne concentrations exceed those limits, use of a NIOSH-approved organic vapor cartridge respirator with full face-piece is recommended. The effectiveness of an air-purifying respirator is limited. Use it only for a single short-term exposure. For emergency and other conditions where short-term exposure guidelines may be exceeded, use an approved positive pressure self-contained breathing apparatus. Do not smoke, eat or drink while working with this product. Avoid contact with skin, eyes and clothing. May cause eye injury. Protective equipment such as gloves, goggles and impervious apron should be used. Carefully read Material Safety Data Sheet and follow all precautions.
Contains Methyl Methacrylate Monomer (80-62-6), Organic Peroxide (94-36-0) and N.N. Dimethylaniline (121-69-7). Do not use this product for other than intended use.
“Title III Section 313 Supplier Notification:” This product contains toxic chemicals subject to the reporting requirements of Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986 and of 40CFR372. This information must be included in all Material Safety Data Sheets that are copied and distributed for this material.
Inhalation: If overcome with vapors, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Call physician.
Eye Contact: Flush with plenty of water for 15 minutes and call a physician.
Skin Contact: Wash skin with plenty of soap and water for at least 15 minutes. If irritation develops, get medical attention.
Ingestion: If swallowed, give 1 or 2 glasses of water or milk. Do not induce vomiting. Contact physician or poison control center immediately.