Kazuo Naito

Oxygen Plasma Treatment of Rubber Surface by the Atmospheric Pressure Cold Plasma Torch

A new application of the atmospheric cold plasma torch has been investigated. Namely, the surface treatment of an air-exposed vulcanized rubber compound. The effect of plasma treatment was evaluated by the bondability of the treated rubber compound with another rubber compound using a polyurethane adhesive. The adhesion property was improved by treatment of the rubber compound with plasma containing oxygen radicals. Physical and chemical changes of the rubber surface as a result of the plasma treatment were analyzed by field emission scanning electron microscopy (FE-SEM) and fourier transform infrared attenuated total reflection (FTIR-ATR).

Studies on oil distribution in polymer blends

Oils and resins are widely used in rubber industries to improve or control the mechanical properties, viscoelastic behavior, processability, and tackiness of a rubber compound. Very few fundamental studies have been reported on the function and the mechanism of oils and resins in a rubber mixture. In this article oil or resin distribution to each phase in an immiscible binary elastomer blend was studied by measuring the change of thermodynamical parameters, such as glass transition temperature, melting point of crystallines, and heat at melt of each polymer component. Several independent approaches give consistent results. It was found that aromatic oil was favorably distributed to the polystyrene-butadiene (SBR) phase of an SBR/natural rubber (NR) blend. Similarly, unequal distribution of resin in a blend was observed for a natural resin (rosin) and a petroleum resin.

Plasma modification of the inner surface of a rubber hose

In order to coat a sufficiently bonded barrier layer onto the inner surface of a rubber hose, plasma modification of the rubber surface prior to the coating was investigated. A stable plasma generation in the rubber hose was obtained when a piece of metal wire was inserted into the hose, while no plasma was available without a wire. Though the surface energy of the rubber was significantly increased by plasma exposure, it decreased with the extended treatment time. The rubber modified by oxygen plasma showed excellent adhesion to coated nylon compared with that treated in argon plasma. With this technique, a high performance, durable hose can be obtained.

Analysis of Crosslinking Structure by Compressive Property of the Swollen Rubber(Part 3).

本報では第一報, 二報で報告した架橋構造解析法の基礎となった, スルフィド結合の選択的切断の吟味を行った. 実験はモデル化合物を用い, ガスクロマトグラフ法により行った. その結果,(1) 一級チオールはポリ, ジ, 両スルフィド結合を迅速に切断し, 水素化アルミニウムリチウムによる切断と一致する.(2) 二級チオールはポリスルフィド結合を切断するが, ジスルフィドとの反応は1/200程度と緩やか.(3) 一級チオールは炭素-炭素結合は切断しない.(4) チオールによるスルフィド結合の切断反応は酸素を除去した系で行う必要がある. 等が確かめられた.

Plasma surface treatment of fluoropolymers at atmospheric pressure

The plasma surface treatment at atmospheric pressure was applied to fluoropolymers and extensive interfacial contact was obtained by using helium gas. Surface analysis suggested that the fluorine was selectively etched and functional groups containing oxygen and nitrogen were produced. These changes increased surface energy. The transmission electron microscopic observation confirmed that microscale roughness of the surface was enhanced. The treated ethylene-tetrafluorinated ethylene films were bonded to a thermostable acrylonitrile-butadiene rubber compound with several adhesives by heat pressing. The urethane adhesive was found to be the best for heat aging.

Modification of polymer in the liquid crystal/polymer complex film

Several kinds of polymers for liquid crystal/polymer complex film (LC/P film) and their modifications had been examined in order to improve their thermal stabilities and mechanical durabilities. Crosslinked rubbery resin; modified poly butadiene, was found to be one of the suitable materials as matrix polymer. The matrix of polymethyl methacrylate, with which satisfactory optical property was available, showed poor thermal stability. The addition of multi-functional monomers which introduced crosslinking structure to the polymer was slightly effective to improve the thermal stabilities, while the matrix of modified polyamide shown inferior optical properties in spite of its desirable stabilities.