Abstract: A silicon single crystal for use as semiconductor is grown by supplying, to a seed rod of single-crystal silicon, hydrochloride gas and silicon formed by admixing at least one chlorosilane gas selected from the group consisting of dichlorosilane, trichlorosilane and tetrachlorosilane with hydrogen gas at a high temperature to grow single-crystal silicon on the seed rod while etching the growing single-crystal silicon with the hydrochloride gas. The silicon single crystal is irradiated with laser rays so that the energy of the laser rays on the irradiated surface of the crystal ranges from 3100 to 3358 mW/cm.sup.2 and then spectra emitted by the crystal are optoelectrically determined to quantify the ultratrace elements present in the silicon single crystal. Moreover, the amounts of these ultratrace elements are reduced to those of ultratrace elements present in the chlorosilane gas.

Abstract: The invention provides a novel method for modifying the surface properties, e.g. antistatic performance and anti-wearing resistance, of a disc-like shaped article made of a vinyl chloride-based resin such as a gramophone record by treating with low temperature plasma so as that the surface of the record is rendered antistatic and the noise generation in playing of the record is remarkably decreased. Different from conventional methods, a great uniformity of the effect by the plasma treatment is ensured by the inventive method all over the surface of the record since the record is transferred through the space between two parallel arrays of electrodes, preferably, with rotation around its axis during the plasma treatment. The manner of connecting the electrodes to the terminals of the high frequency generator may be in two different ways.

Abstract: The invention provides a novel method for the preparation of a composite shaped article of a vinyl chloride-based resin clad with a coating layer of polyvinyl alcohol without the use of any adhesive agent. The method comprises subjecting the surface of the shaped article to exposure to an atmosphere of low temperature atmosphere, coating the thus plasma-treated surface of the shaped article with an aqueous solution of a polyvinyl alcohol and drying. The coating layer of the polyvinyl alcohol thus formed is so firmly bonded to the surface of the vinyl chloride-based resin shaped article that various advantageous properties are imparted to the shaped article.

Abstract: A novel method is proposed for improving the surface properties or, in particular, for increasing the affinity to water of the surface of a shaped article made of a silicone, e.g. a silicone rubber. The inventive method comprises first exposing the surface of the shaped article of the silicone to low temperature plasma of an inorganic gas and then bringing the plasma-treated surface into contact with a liquid inert to the silicone which is an aqueous solution containing a surface active agent. The treated surface retains sufficient affinity to water even 6 months after the treatment.

Abstract: A novel method is proposed for improving the surface properties or, in particular, for increasing the affinity to water of and for reducing accumulation of static electricity on the surface of a shaped article made of an acrylic resin. The inventive method comprises first exposing the surface of the shaped article to low temperature plasma of a gas having no polymerizability in plasma and then bringing the plasma-treated surface into contact with an aqueous solution containing a surface active agent. The effect of the inventive method is so strong and durable that the treated surface remains antistatic even 6 months after the treatment.

Abstract: The invention provides a novel method for modifying surface properties, e.g. liability to surface bleeding of plasticizers and other additives and affinity with water, of shaped articles of polymeric materials such as vinyl chloride-based resins and silicone rubbers by the treatment with low temperature plasma of a gas. The plasma treatment in the inventive method is carried out in two steps with the first step carried out in an atmosphere of oxygen and the second step carried out in a non-oxidizing gas such as argon and carbon monoxide. Different from the conventional methods of plasma treatment which suffer from poor reproducibility and low effectiveness, the inventive method can give good reproducibility and high effectiveness presumably owing to the removal of the surface stain in the first step plasma treatment.

Abstract: The undesirable phenomenon of bleeding of, for example, a plasticizer contained in a shaped article of a plasticized polyvinyl chloride resin on the surface of the article in a long-run use is effectively prevented by the inventive method and the effectiveness of the method is durable over a long period of time even when the article is used in an outdoor environment or under irradiation with ultraviolet light. The method of the invention comprises the first step of exposing the surface of the article to an atmosphere of low temperature plasma of an inorganic gas and then the second step of contacting the thus plasma-treated surface with a halogen or hydrogen halide, preferably, in gaseous state.

Abstract: The invention provides a novel means for the improvement of the surface properties of a gramophone record made of a vinyl chloride-based resin which is deficient in respect of the susceptibility to electrostatic charging and anti-wearing resistance with consequent noise generation in the playing of the record. The inventive method comprises irradiating the surface of the gramophone record with ultraviolet light having a substantial energy distribution in the wavelength region of 200 nm or shorter in an atmosphere of oxygen or an oxygen-containing gaseous mixture of which the pressure or partial pressure of oxygen is at least 15 Torr. The effect of the ultraviolet irradiation is further enhanced and the durability of the antistatic effect is increased by bringing the ultraviolet-irradiated surface of the gramophone record into contact with a solution containing a surface active agent followed by washing with water and drying.

Abstract: The invention provides a novel method for the preparation of a polarizing film or sheet based on a polyvinyl alcohol which is easily prepared and easy to handle. The inventive method comprises first subjecting a substrate film or sheet of a vinyl chloride resin to exposure to low temperature plasma, the surface of the substrate is coated with an aqueous solution of a polyvinyl alcohol and dried so as that a coating layer of the polyvinyl alcohol is formed as firmly bonded to the substrate surface owing to the increased affinity of the surface by the plasma treatment, the thus polyvinyl alcohol-clad substrate is stretched as such unidirectionally and the stretched polyvinyl alcohol layer is treated with iodine to be imparted with a polarizing power. The adhesion between the substrate and the polyvinyl alcohol layer is so strong without an adhesive agent that the difficulty in the prior art in handling fragile stretched polyvinyl alcohol film is completely overcome.