Polycarbonate bonding, adhesive

SBR, polycarbonates, etc., can often be achieved by choosing a polyol backbone that is similar in polarity to the substrate to be bonded. For example, polyethers often work well for obtaining adhesion to these medium polarity plastics, whereas polyesters usually work better for polar substrates, such as glass and metal. 

Ibid, A Thermoplastic Transparent Adhesive for Bonding Polycarbonate to Glass , Report No AMMRC CR-71-10, Contract DAAG46-71-... 

The major uses of BPA are in the production of polycarbonate resins (63%) and epoxy resins (27%). Polycarbonates have major outlets in automotive parts, compact discs, eyeglasses, and sheet and glazing applications, and have caused bisphenol A consumption to more than double during the past decade. Epoxy resins are two-component adhesives for very strong bonding. Miscellaneous uses include flame retardants (mostly tetrabromobisphenol A) and other polymer manufacture. Polycarbonate grade bisphenol A is >99% p,p isomer. The epoxy grade is 95% p,p. The p,p and o,p isomers can be separated by a combination of distillation and crystallization. 

In the medical field, UV curable adhesives are used in fhe assembly of medical devices, such as syringes, valves, manifolds for filtering equipmenf, and arteriographs. In these applications, many dissimilar substrates, such as stainless steel, aluminum, glass, polycarbonate, polymethyl methacrylate (PMMA), PVC, and other thermoplastics, are bonded. ... 

A numerically controlled mill fabricated trenches and through holes at the ends of the trenches in a thin, colorless, polyacrylic acid plate [26], This thin plate was bonded to a more rigid, transparent polycarbonate base plate with U V-curing optical adhesive. The through holes in the plate were connected to holes in the base plate, thereby forming one conduit. The latter holes did not penetrate the base plate, but rather were connected to cross-type arranged borings. Thereby, fluid connections could be attached to the side of the base plate. 

An infrared C02 laser (1060 nm) was used to cut through a polycarbonate PC (black) (carbon-coated) wafer of 250-pm thickness to create microfluidic channels. The laser-machined black PC wafer was then thermally bonded between two transparent PC wafers at 139°C under two tons of pressure for 45 min [937], A C02 laser was also used to ablate Mylar sheets (with adhesive). Then the machined Mylar sheets were laminated together [1051]. Moreover, a PMMA substrate was machined by a C02 laser [201,202]. However, the microchannel ( 200 pm deep) has a Gaussian-like cross section and a certain degree of surface roughness [201], The C02 laser has also been used to machine PET substrates [203],... 

It is advisable to use a stainless steel, glass or wood spatula and a clean working area (glass, aluminum foil) or a disposable plastic cup for the mixing of adhesives (preferably polythylene or polypropylene since plastics like polystyrene, polycarbonate or polyvinyl chloride may swell due to components of the adhesive). Tip For frequent bonding processes with low adhesive consumption, even so-called pill cups (content approximately 20 ml) of polyethylene or polypropylene are suitable, which are available in drug stores. 

These adhesives have been found to adhere strongly to metals, glass, wood, ceramics, masonry, asphalt, leather, and plastics like polystyrene, phenolics, polycarbonates, ABS, cellulose acetate, polyesters, rubbers, and some polyolefins. In general, the most favorable results are noted in the bonding of steel and aluminum, perhaps because the bond strengths are more easily observed before substrate failure. 

For bonding molded parts of polycarbonate to other plastics, glass, wood, aluminum, brass, steel, and other materials, a wide variety of adhesives can be used. Generally, the best results are obtained with solventless materials, such as epoxies and urethanes. 

The transportation market has used polyurethane adhesives for such diverse applications as bonding FRP and sheet molding composite (SMC) panels in truck and car applications, polycarbonate headlamp assemblies, door panels, and weatherstrip flocking. 

Company literature from several adhesive suppliers is currently available that lists UV curable and visible light curing acrylic adhesives as part of their product package. This type of acrylic adhesive is being used successfully in polycarbonate lens bonding. 

Bondable substrates for aerobic and second-generation acrylics include clean as well as oily or "as received" metal polyurethanes, filled polycarbonates, filled nylon, phenolics, thermosets, wood, concrete, ceramics, glass, and other common materials of manufacture. Some thermoplastic materials are bonded better by using a second-generation acrylic adhesive. Examples are unfilled nylon, ABS, and rubber. 

A polycarbonate TPE polyurethane that claims biostability is achieved through its replacement of virtually all ether or ester linkages with carbonate groups. The soft segment is composed of a polycarbonate diol formed by the condensation reaction of 1,6-hexanediol with ethylene carbonate. The polycarbonate diol is converted to a high molecular weight polyurethane by the reaction with 1,4-methylene bisphenyl diisocyanate (MDI) and 1,4-butanediol. It is reported to be resistant to environmental stress cracking as experienced with insulation on pacemaker lead wires. The polymer can be extruded, injection molded or compression-molded, and can be bonded with conventional urethane adhesives and solvents (Tables 4.4, 4.12, 4.13, and 4.14). 

Methylene chloride when used alone has an extremely fast evaporation rate. This solvent is recommended for most temperate climate zones and small areas. A solution of 1-5% of polycarbonate in methylene chloride can be used in extreme cases where perfectly mated bonding areas are impossible to obtain. A mixture of methylene chloride with a maximum of 40% ethylene dichloride may be used, where it is difficult to join parts quickly enough to prevent complete evaporation of methylene chloride. The evaporative rate of methylene chloride is 6.7 times faster than that of ethylene dichloride. Bonds made with the mixture have strengths of 62.1-69.0 MPa. Tensile-shear strengths of 31.0-44.8 MPa have been obtained by General Electric after 48 hours of setting at room temperature for both methylene chloride and ethylene chloride solvent bonds. This is superior to conventional adhesive-bond tensile-shear strengths of 2.41-20.0... 

Aliphatic TPUs based on isocyanates like methyldicyclohexyl diisocyanate (H12 MDI), 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) are light stable and offer excellent optical clarity. They are commonly employed in automotive interior and exterior applications and as laminating films to bond glass and polycarbonate together in the glazing industry. They are also used in projects where attributes like optical clarity, adhesion, and surface protection are required. 

Adhesion between the plies is partially mechanical since the materials are molten when combined, but the major bond has to be chemical (see Theories of adhesion). Where compatible materials are used, such as low-density polyethylene or high-density polyethylene (LDPE/HDPE), strong bonds can be achieved between the layers without additional means (see Compatibility). However, where the wider opportunities to use coextrusion are taken and multi-layers conceived with non-compatible materials such as polyamides, polyolefins, polycarbonate and polyethylene vinyl alcohol, adequate adhesion may be difficult to achieve. In these circnmstances, a specific polymeric layer may be used to act as a compatibilizing agent or Tie layer. A very thin layer of the extrudable adhesive has functional gronps to enhance the chemical bonding at the interface. 

The adhesives will bond almost all materials (though a primer may be needed with some), except polyolefin plastics (eg Polythene) and other low surface-energy types such as fluoropolymers (eg Teflon) and silicone-based rubbers. Alkaline glass may cause premature bond failure and all glasses should be silane primed if at all possible, as this considerably improves the joint s humidity resistance. May stress crack stressed mouldings or susceptible plastics - polycarbonate, for example. 

The hydrosilylation of unsaturated polymers (e.g, polybutadiene, polyiso-prene, polyesters, polyenes, and polycarbonates) with a silane having hydrolyzable substituents at silicon atoms leads to polymeric systems with enhanced activity toward mineral fillers (32). Such process also offers a useful and convenient method for preparing silane-modified polymers that may find potential applications as rubber materials, adhesives, and drug delivery agents. Both >C=C< as well >C=0 bonds are capable of hydrosilylation. This modification is connected with a reversed use of the silane (siloxane) coupling agents. Trialkoxysilyl groups are commonly incorporated onto the polymers by Pt-catalyzed hydrosilylation... 

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