Abstract: By reacting a chloromonosilane or chlorodisilane with a halogenated hydrocarbon in a liquid phase in the presence of metallic aluminum or an aluminum alloy, a hydrocarbon group is substituted for at least one chlorine atom of the chlorosilane for introducing hydrocarbon into the chlorosilane. Silanes having a high degree of hydrocarbon substitution can be easily synthesized from chlorosilanes under moderate conditions and with high volumetric efficiency. The reagents used are aluminum or aluminum alloys and halogenated hydrocarbons which are inexpensive and readily available.

Abstract: To a silicone rubber composition including (A) a diorganopolysiloxane having an aliphatic unsaturated hydrocarbon group, (B) an organohydrogenpolysiloxane having at least two SiH groups in a molecule, and (C) a platinum catalyst, is added (D) an organic silicon compound of the following general formula (2): ##STR1## wherein R.sup.2, R.sup.5, and R.sup.6 are independently selected from monovalent hydrocarbon groups free of an aliphatic unsaturated bond, R.sup.3 is a monovalent hydrocarbon group, R.sup.4 is hydrogen or methyl, and n is an integer of 0 to 3. The composition has a long pot life after addition of curing components (B) and (C) and is extrusion moldable into bubble-free transparent parts. The composition is prepared by mixing component (A) with components (B) and (C) while adding component (D) thereto.

Abstract: A silacyclohexane compound represented by the following general formula (I). ##STR1## In this formula, R denotes a linear-chain alkyl group with a carbon number of 1-10, a mono- or di-fluoroalkyl group with a carbon number of 1-10, a branched-chain alkyl group with a carbon number of 3-8, an alkoxyalkyl group with a carbon number of 2-7, or an alkenyl group with a carbon number of 2-8. ##STR2## denotes a trans-1-silacyclohexylene or trans-4-silacyclohexylene group whose silicon at position 1 or position 4 has a substitutional group(s) of H, F, Cl or CH.sub.3. X denotes a CN, F, Cl, CF.sub.3, CF.sub.2 Cl, CHFCl, OCF.sub.3, OCHF.sub.2, OCF.sub.2 Cl, OCHFCl, R or OR group. Y denotes H or F. Z denotes H or F.

Abstract: Polyimides comprising recurring units of the following general formula (1) ##STR1## wherein Ar.sub.1 represents a tetravalent aromatic group and each Ar.sub.2 represents a divalent aromatic group. Polyimide copolymers and preparations of the polyimides and the polyimide copolymers are also described.

Abstract: A heat-curable silicone elastomer composition comprising (A) a thermoplastic resin containing a platinum catalyst and a hydrosilylation reaction retarding agent, (B) an organopolysiloxane having at least two unsaturated aliphatic hydrocarbon groups bonded to silicon atoms in its molecule, and (C) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in its molecule. The composition is excellent in storage stability. That is, even when stored for a long time, the composition has good stability at room temperature and retains curability at high temperatures.

Abstract: A process for producing a polymer of a monomer having an ethylenically unsaturated double bond is described, wherein the monomer is polymerized in a polymerization vessel having a coating on its inner wall surfaces of a specific three-component polymer scale preventive agent, these three components are a naphthoquinone dimer, a water soluble polymer, and an inorganic colloid, whereby polymer scale is prevented from being deposited on the inner wall surfaces of the polymerization vessel.

Abstract: A method for reducing the number of contaminative live bacteria in xanthan gum which comprises the step of washing a mixture of 100 parts by weight of water-containing isopropanol having an isopropanol concentration of 50 to 100% by weight and 1 to 100 parts by weight of the xanthan gum under heating conditions.

Abstract: An apparatus for automatically determining the rate of plasticizer absorption of a powdery resin sample such as a vinyl chloride resin sample. The apparatus for automatically determining the rate of plasticizer absorption of a powdery resin sample is one in which the rate of plasticizer absorption is determined by treating, in a centrifugal separator 10, a powdery resin contained in an inspection container 2 together with an excess of a plasticizer, to remove from the powdery resin sample the excess plasticizer, and determining the amount of the plasticizer absorbed by and remaining in the powdery resin.

Abstract: Proposed is a novel face coat composition having improved stability used in the preparation of a shell-like casting mold for a high melting point metal or alloy by the lost-wax mold method by forming a face coat layer on a wax model using the composition and further forming a backup coat layer thereon followed by removal of the wax by melting and calcination of the shell-like mold formed from the layers. The face coat composition comprises a rare earth oxide powder as the refractory constituent and a binder which is a synthetic resin in the form of an aqueous emulsion, a water-soluble organic polymer in the form of an aqueous solution, a sol of an inorganic oxide such as aluminum oxide, silicon dioxide and zirconium oxide or a combination thereof. A small amount of a powder of rare earth glass can be admixed to the composition so that the face coat layer formed from the face coat composition may have still improved properties.

Abstract: A film forming composition, comprising an amine-modified highly polymerized polysiloxane represented by the general formula (1): ##STR1## wherein R, which are the same or different, each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, a hydroxyl group, or a hydrogen atom, R' each represent an amino-group-containing organic group, a is an integer of 0 to 3, m is an integer of 1 or more, and n is an integer of 5 or more, provided that m+n is an integer of 2,000 or more, and dissolved in an organic solvent, which film forming composition can give a smooth soft film that is excellent in water repellency, water resistance, touch, and durability in comparison with the conventional film forming compositions.

Abstract: A hydrolyzate resulting from co-hydrolysis of a perfluoroalkyl group-containing organic silicon compound and a hydrolyzable group-containing methylpolysiloxane compound in a hydrophilic solvent and water constitutes a water repellent agent which is effective for imparting water repellency and facilitating falling of water droplets and thus imparting excellent water repellency and stain-proofness to a surface of an article treated therewith.

Abstract: A manufacturing method of organosilanes having silanol groups which is characterized by mixing organoalkoxy silanes, having at most a 20 ppm content of chlorine, expressed by the general chemical formula (1) below:Si(R.sup.1).sub.m (R.sup.2).sub.n (OR.sup.3).sub.k (1)wherein each of R.sup.1 and R.sup.2 is either a substituted or unsubstituted monovalent hydrocarbon group; R.sup.3 is an alkyl group of 1 to 4 carbon atoms; subscripts m and n are 0, 1, 2, or 3; k is either 1 or 2; and the sum of subscripts m+n+k=4, with ion-exchanged water having an electroconductivity of at least 10.sup.10 M.OMEGA., then further adding a macro-porous cation-exchange resin with a pore volume measured by the mercury injection method of at least 0.1 ml/g to the said mixture, followed by stirring of the mixture and removal of the cation-exchange resin.

Abstract: Disclosed is a water-based printing ink composition exhibiting excellently low foaming behavior with sustainability even under adverse conditions of high temperature and intense shearing force encountered in the printing works. The printing ink composition comprises, besides an organic polymer as the binder resin in the form of an aqueous solution or emulsion and a coloring agent, e.g., dyes and pigments, a silicone-based defoaming composition comprising a polyoxyalkylene-modified polydiorganosiloxane, polydimethylsiloxane, finely divided silica filler and organopolysiloxane resin mainly or solely consisting of monofunctional organosiloxane units and tetrafunctional siloxane units each in a specified weight proportion.

Abstract: A polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a water-soluble basic polysaccharide and (B) a phenothiazine. The process is used for forming a coating on the inner wall, etc. of a polymerization vessel, and highly safe for operators. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness or a low initial coloration is obtained.

Abstract: A room temperature vulcanizable composition comprises a diorganopolysiloxane blocked with a silanol group at both ends of the molecular chain, an organopolysiloxane having at least three silanol groups in the molecule, and at least one member selected from the group consisting of organosilanes and organopolysiloxanes each having two hydrolyzable groups in one molecule. The composition ensures easy control of its working life and is able to yield a cured product having a low modulus over a long time.

Abstract: This invention provides a primer composition comprising (A) a polyorganosiloxane resin containing at least 0.01 mole of hydroxyl groups per 100 g of the resin represented by the average composition formula: (R.sup.1).sub.a SiO.sub.(4-a)/2 wherein each R.sup.1 represents a substituted or unsubstituted monovalent hydrocarbon group, and a is a value of 0.4 to 1.8; (B) an alkoxytitanium or a partially hydrolyzed product thereof; (C) an acid; and (D) a solvent. The primer composition can strongly adhere a condensation type room temperature curable silicone elastomer to the surface of the coated metal formed by applying a fluororesin coating, an acrylic resin coating or the like to a metal.

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: A polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising an alkaline solution containing a condensation product of (A) an aromatic amine compound having at least two amino groups and (B) an aromatic tetracarboxylic acid anhydride. This process is used for forming a coating on the inner wall, etc. of a polymerization vessel. Such a vessel is effective in preventing polymer scale deposition and useful in producing a polymer that shows very few fish eyes and good whiteness when formed into sheets or the like.

Abstract: A polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising an alkaline solution containing (A) a condensation product of (A-1) an aromatic compound having at least two amino groups with (A-2) an aromatic tetracarboxylic acid anhydride, and (B) at least one member selected from the group consisting of (B-1) a water-soluble polymeric compound and (B-2) an inorganic colloid. The scale preventive process is low in virulence or the like, and high in safety. The process is used for forming a coating on inner wall surfaces of a polymerization vessel. Where such a polymerization vessel is used to carry out the polymerization, polymer scale deposition can be effectively prevented, not only on areas in the liquid-phase region but on areas around the gas-liquid interface in the vessel, and the resulting polymeric product shows few fish eyes and good whiteness when formed into sheets or the like.

Abstract: A room temperature curable rubber composition of a condensation curing type that comprises as a base polymer a diorganopolysiloxane or a polyoxyalkylene in which both ends of the molecular chain are blocked with a hydrolyzable silyl group, and a .beta.-dicarbonyl compound and an amino group containing organic compound that are blended with the base polymer. Since the room temperature curable rubber composition is cured with water in the air and at the same time the dehydration condensation of the .beta.-carbonyl group and the amino group produces water in the composition, the quick curability and deep curability are improved remarkably. In addition, since this dehydration condensation reaction is an irreversible reaction, the product produced by the condensation dehydration is hydrolyzed to prevent the amino group containing compound from being regenerated, and as a result the hydrophilic nature of the cured product is prevented from increasing not to damage the water resistance.