Tsutomu Noguchi

A new recycling system for expanded polystyrene using a natural solvent. Part 1. A new recycling technique

A new recycling technique has been developed which uses a natural solvent, d limonene, to shrink expanded polystyrene (EPS). d-Limonene is a natural vegetable oil which is extracted from the rinds of citrus fruits and is a good solvent of EPS. Limonene has almost the same solubility as toluene at room temperature. This technique reduces the volume of EPS to about 1/20th of the original. Contracted EPS is recyclable with almost no molecular weight degradation because d-limonene acts as an antioxidant of polystyrene during the heating process.

A new recycling system for expanded polystyrene using a natural solvent. Part 2. Development of a prototype production system

A prototype production system for recycling expanded polystyrene (EPS), which uses an orange oil, d-limonene, as the EPS shrinking agent, has been developed. This system consists of an apparatus to dissolve EPS and a recycling plant to separate the limonene solution. The recycling plant can mass reproduce polystyrene with the same mechanical properties as new polystyrene. The recycled polystyrene can be used for packaging a 28 inch TV set.

A new recycling system for expanded polystyrene using a natural solvent. Part 3. Life cycle assessment

A new system of recycling expanded polystyrene has been developed which uses limonene orange oil as a solvent to recycle high grade polystyrene. Life cycle assessment was applied to this system to simulate its effect on the environment. It is shown that the new system has a lower greenhouse effect (−30%), acidification (−58%) and energy consumption (−20%) than the conventional recycling system using thermal shrinking.

Electron beam curing of acrylic oligomers

Abstract The electron-beam curing process of acrylic oligomers, with and without γ-Fe2O3 pigment filler and blended linear polymer, was investigated in terms of molecular structure and reaction mechanism. The polymerized fraction of trimethylolpropane-triacrylate (TMPTA) oligomers increases with increasingly total dose, and is independent of the dose rate. Since the reaction rate is linearly dependent on the dose rate, the reaction mechanism involves monomolecular termination. The reaction rate does not depend on the number of functional groups of the oligomer at low doses, but above 0.3 Mrad the rate is slower for oligomers of higher functionality. A gel is formed more readily upon curing of a polyfunctional than a monofunctional oligomer, especially at high conversion to polymer; the resulting loss of flexibility of the polymer chains slows the reaction. Decrease of the molecular weight per functional group results in lower conversion; this is also due to the loss of chain flexibility, which is indicated as well by a higher glass-transition temperature. Modification of the acrylate oligomers with urethane results in more effective cross-linking reactions because of the more rigid molecular chains. Addition of γ-Fe2O3 pigment reduces the reaction rate very little, but has the effect of providing added structural integrity, as indicated by the decrease of solvent-extractable material and the improvement of anti-abrasion properties. However, the flexibility of the coating and its adhesion to a PET base film are diminished. To increase the flexibility, linear polyvinylchloride and/or polyurethane were added to the acrylic oligomers. Final conversion to polymer was nearly 100 per cent, and a higher elastic modulus and better anti-abrasion properties were realized.

Development of moulded pulp materials for the packaging of electronic equipment

A new shredded pulp–plastic microsphere composite with modified starch binder which is applicable to the packaging of electronic equipment has been developed. This composite with a 3 wt% microsphere content has almost the same compressive stress at 50% compressive strain as that of (poly)styrene foam, which has a specific gravity of 0.025. A moulded sample of the above composites can be released from a mould after 1.5 minutes of steam heating, the same cycle time as that of styrene foam.

A Novel Silicon-Containing Resist For A Bi-Layer Resist System

A new positive working photoresist which is applicable to the bi-layer resist system using a current g-line stepper has been developed. This resist consists of a naphthoquinone diazide photoactive compound and a silicon containing novolak resin, which is synthesised from phenols with siloxane groups(-Si-O-), and formaldehyde by condensation reaction. The Si-containing resist has a resolution capability of 0.5μm L/S with a g-line sensitivity about 250 mJ/cm2, and a high resistance to oxygen plasma, with an etching rate ratio of 61:1(photoresist/Si resist). 0.5μm L/S pattern was precisely transferred to the bottom layer by 02 RIE with vertical side walls.

NEW PULP MOLD MATERIALS FOR THE PACKAGING OF ELECTRONIC EQUIPMENT

A new pulp-plastic microsphere composite which is applicable to the packaging of electronic equipment has been developed. This composite with a 10wt. % microsphere content has a compressive stress 80% lower than a conventional pulp mold at 50% compressive strain, and has almost the same compressive stress as that of styrene foam, which has a specific gravity of 0.02. The composite has a low compressive stress because the microspheres have a low specific gravity (0.02), and a shock absorbing property and the voids are uniformly distributed. The new pulp mold is promising as a material to replace styrene foam.

Novolak resin design concept for high-resolution positive resists

A new novolak-type photoresist which is applicable to excimer laser lithography has been developed. This resist consists of a naphthoquinonediazide-4-sulfonyl ester(NQD-4) and branched novolak resins, which are synthesized in an excess formalin/m-cresol molar ratio (1approximately equals 2) condition. The branched novolak resin-NQD-4 pendent resist (BNP resist) has about two times higher sensitivity than a conventional novolak resist (PR-1024MB) and exhibits clearly a surface development induction, which affords higher (gamma) -values. Copolymerization of hydroquinone (HQ) improves the sensitivity, resist profile, and mask linearity of the BNP resist. The BNP-HQ resist has a resolution capability of 0.35 micrometers lines and spaces with a KrF excimer laser sensitivity of about 170 mJ/cm2. Therefore, our design concept of novolak resin is applicable to high resolution positive resists and especially to excimer resists.