The biodegradable polyester emulsion adhesives were investigated with reference to the adhesion enhancement and the blocking resistance, employing polybutylene succinate-co-adipate (PBSA) emulsion and polycaprolactone (PCL) emulsion and the following results were obtained.1. It was observed that water dispersible aliphatic polyisocyanate was an effective additive for the adhesion enhancement without affecting biodegradability, that is, polyester emulsion films were toughened and the adhesion was enhanced in bonded products such as heat-sealed cellophane, bonded cotton fabrics and impregnated paper. From analytical calculations it was concluded that the adhesion was enhanced by the formation of a comparatively small number of chemical bonds between the polyester emulsion films as glue lines and the adherends.2. PBSA emulsion was found to be an extremely useful additive to improve blocking resistance of widely used EVA emulsion adhesives where the surface free energy of the blended emulsion film was far from those of the original, being close to that of polyethylene.

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The effect of tackifier on the adhesive property of the pressure sensitive adhesive tape was investigated. For this purpose, a model system consisting of polystyrene-polyisoprene-polystyrene tri-block copolymer as base polymer and a typical aliphatic petroleum resin as tackifier was prepared. The tackifier content ranged from 10 to 60wt%. The tackifier used has good a compatibility with polyisoprene, whereas, it has a poor compatibility with polystyrene. The 180°peel adhesion was measured. The peel adhesion increased with the tackifier content, while the degree of increase became significantly above 40wt%. The pressure sensitivity appeared clearly and the maximum peel adhesion obtained without heating above 40wt%. The phase structure was determined using pulsenuclear magnetic resonance, transmission electron microscope and dynamic mechanical analysis. The phase structure that the spherical polystyrene domains having the mean size of about 20nm were dispersed in the polyisoprene continuous phase was observed. The formation of tackifier-rich phase of the order of nm in the polyisoprene matrix was observed and the amount increased with the tackifier content. The tackifier-rich phase seemed to develop the cohesive strength of the pressure sensitive adhesive, and thus it increased the peel adhesion.

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To investigate degradation factors of Ag-epoxy conductive adhesive after reliability test, the electrical resistance and adhesion strength of the samples were evaluated. Reliability tests, such as 358K/85% test and thermal shock test were carried out for 0, 250, 500, 750 and 1000 hours/cycles respectively. The crack was formed at the interface between chip and conductive adhesive due to the difference of thermal expansion coefficient and the shrinkage occurred during the thermal shock test. The crack was initiated at the joint, and propagated along the joint between chip and conductive adhesive. While approaching to another edge of the chip, the crack tended to advance into the matrix of conductive adhesive. Moreover, it is presumed that the oxide film generated at the interface between Sn/Ni plating of chip and conductive adhesive during the 358K/85% test, or the moisture moving into the crack during reliability test, will impact the joint reliability, namely, electrical resistance and adhesion strength. On the other hand, the reliability of conductive adhesive deteriorated with silver particle content in conductive adhesive increased.

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In acrylic-silicone polymer (CAS) solutions, silica micro particles were synthesized by addition of tetraethoxysilane (TEOS) and hydrophobic silane coupling agent (SCA). The morphology of the micro particles and the surface properties of the coating deposited with silica dispersions were examined. Effects of solvent types, concentration of CAS and SCA on these properties were also investigated.The diameter of the particles was depressed by addition of CAS in EtOH/H2O and IPA/H2O solutions (400-500nm→80-100nm), and it was further smaller by using both CAS and SCA (20-100nm). From the results of XPS, the peak ratios of C/Si increased by addition of CAS or CAS-SCA. It was considered that a part of silicone blocks and hydrophobic groups of SCA were localized on particle surface. When CAS-silica colloid was coated on a glass substrate, the contact angle value (CA) increased with CAS concentration and showed maximum value. The CA of the CAS-silica was larger than that of the CAS independently coated, and the CA of the CAS-SCA-silica was >150°. It was thought that in the preparation reactions, the carboxyl groups in CAS were interacted with silica precursor and a part of the CAS were being included into the silica particles. By using both CAS and SCA, bulky hydrophobic groups, e.g. trimethylsilil, were also introduced in the silica surface. The particle diameter depression and the improvement of the CA were attributed to the introduction of silicone blocks and hydrophobic groups on surface of the silica particles. A Super water-repellent surface could be prepared by combining hydrophobic surface and the unevenness of the silica particles.

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