Abstract: Finely powdered high-purity fibroin and a process for producing the same are disclosed. The fibroin is a fine powder of fibroin in nonfibrous and particulate form which has an average molecular weight of not less than 50,000, particle diameters of from 1 to 100.mu., and a bulk density of from 0.1 to 0.7 g/cm.sup.3 as measured in the dry state and which contains at least 50% by weight of hot-water-insoluble fibroin having the .beta.-configuration. The process comprises dissolving a degummed silk material in an aqueous salt solution containing from 5 to 80% by weight of an alkali metal salt or alkaline earth metal salt; dialyzing the resulting aqueous fibroin solution; adding from 1 to 150 parts by weight of an alcohol to 100 parts by weight of the dialyzed aqueous fibroin solution having a fibroin concentration of from 3 to 20% by weight to form a gel of fibroin; dehydrating and drying the gel so formed; and then pulverizing the resulting powder.

Abstract: An alkali resistant glass composition comprising the following oxides in a weight percentage composition of 57 - 64% SiO.sub.2, 19 - 23.5% ZrO.sub.2, 0.5 - 2.5% Li.sub.2 O, 11 - 18% Na.sub.2 O, 0 - 6% K.sub.2 O, 0 - 0.5% RO, 0 - 0.5% Al.sub.2 O.sub.3 and 0 - 0.5% M.sub.x O.sub.y wherein R is an alkaline earth metal, M is a metal other than an alkaline earth metal, and x and y are positive integers where (valence of M) multiplied by x = 2y, and satisfying the relationships defined by following expressions (1) and (2):21 .gtoreq. Na.sub.2 O + Li.sub.2 O + K.sub.2 O.gtoreq. 15.5 (1)52 - 2zr.sub.2 O.gtoreq.4Li.sub.2 O - K.sub.2 O.gtoreq.ZrO.sub.2 - 21 (2);and alkali resistant glass fibers prepared therefrom.

Abstract: An alkali resistant glass composition and alkali resistant glass fibers composed of said glass composition which comprises______________________________________ SiO.sub.2 61 - 69 mole% , ZrO.sub.2 11.5 - 12.5 mole% , CaO 2 - 5 mole% , R.sub.2 O 16 - 20 mole% , K.sub.2 O 2 - 5 mole% , B.sub.2 O.sub.3 1 - 4 mole% , TiO.sub.2 0 - 0.3 mole% , and M.sub.x O.sub.y 0 - 1 mole ______________________________________Wherein R.sub.2 O represents the total amount of Na.sub.2 O and K.sub.2 O; M is at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Cu, Zn, As, Y, Mo, Cd, Sn, Sb, Hf and Ce; x and y are positive integers with the proviso that the valence of M multiplied by x equals 2y; and the content of fluorides, calculated as F.sub.2, is 0 to 1 mole%, and meeting the following conditions,A. r.sub.2 o + caO .gtoreq. 19 mole%,B. zrO.sub.2 + CaO + B.sub.2 O.sub.3 .ltoreq. 18.5 mole%, andC. the molar ratio of K.sub.2 O/CaO .gtoreq. 0.5.

Abstract: Heat resistant and flame resistant papers composed of at least 60% by weight of phenolic fibers having a hardened degree of 3-30% by weight, which are obtained by melt spinning a phenolic resin and cross-linking the resulting filaments with an aldehyde.

Abstract: A process for producing an anion-exchangeable nonhollow novolak filament which comprises treating a cured nonhollow novolak filament with an amination agent thereby introducing an anion-exchangeable group into the filament.

Abstract: Infusible and insoluble styrene copolymeric fibers are prepared by copolymerizing styrene with an olefinic compound having at least one functional group selected from haloalkyl group, amino group, carboxyl group, carbonic acid ester group, carbonic acid halide group, hydroxyl group, amido group, nitrile group and halogen atom, melt spinning the resulting styrene copolymer into fibers and treating the formed fibers with a cross-linking agent to form three dimensional cross-linkages in the fibers.

Abstract: Light-focussing type optical fibers are formed from concentric circular sheath-core composite fibers composed of a sheath forming polymer having a defined solubility parameter and a defined swelling parameter, which can protect the core, and a core polymer wherein a specific monomer is introduced through the sheath into the core polymer, after which said monomer is polymerized, whereby the defined variation of refractive index from the center of the core towards the periphery of the core is formed.

Abstract: A method of producing a self-crimping composite fiber of phenolic resin having heat-resistant and flameproof properties which comprises compositely spinning a thermoplastic phenolic resin and a modified phenolic resin consisting of a thermoplastic resin and another thermoplastic resin, such that the two components are united in either an eccentric or side-by-side arrangement, and thereafter curing the resulting thermoplastic composite fiber.

Abstract: An alkali resistant glass composition comprisingSiO 55 to 69 mol% ZrO.sub.2 11.5 to 14 mol% R.sub.2 O 12 to 23 mol% B.sub.2 O.sub.3 1 to 6 mol% P.sub.2 O.sub.5 1 to 5 mol%Wherein R represents an alkali metal, the content of R'O, R' being an alkaline earth metal, does not exceed 0.5 mol%, and the content of fluorides, calculated as F.sub.2, does not exceed 1 mol%. Alkali resistant fibers prepared from the glass composition, and a cementitious product reinforced with the alkali resistant fibers.

Abstract: A radiation shielding phenolic fiber comprising (A) a filamentary phenolic polymer consisting predominantly of a sulfonic acid group-containing cured novolak resin and (B) a metallic atom having a great radiation shielding capacity, the metallic atom being incorporated in the polymer by being chemically bound in the ionic state in the novolak resin; a fibrous material, such as fibers, yarns, knit fabrics, woven fabrics, non-woven fabrics, felt, mat, composed of the aforesaid radiation shielding phenolic fiber; and a method for the production thereof.

Abstract: A lead-acid storage battery, in one aspect of this invention, comprises units of cells each having, between alternate fibrous structure and negative plate which are arranged in laminated fashion on each side of a positive plate which is coated on both surfaces with an anode active material, a separator comprised of a paper-like sheet having continuous micro-porous openings throughout the entire area thereof and containing at least 70% by weight of phenol resin fibers each having a diameter of 5 microns or less produced by melt-spinning and curing a novolak resin. A lead storage battery having such separators is of an improved cell capacity and output and a prolonged life span. In another aspect of the invention, the separators are such that said phenol resin fibers have at least 60% by mole of the phenolic hydroxyl groups of the resin capped. A battery employing these separators is of further improved duration and satisfactory cell capacity and output.

Abstract: A process for producing a hollow carbon or ion-exchange filament which comprises treating a filament consisting of a fiber-forming polymer of predominantly an uncured novolak resin composition with a curing reagent in the presence of a curing catalyst to effect the cure of the filament extending from the peripheral portion to the axial portion thereof to a depth of 20-90% of the cross-sectional area of the filament, removing the uncured core portion of the filament by extraction with a solvent, and then subjecting the resulting hollow novolak resin filament to a carbonization treatment or introducing an ion-exchangeable group into the resulting hollow novolak resin filament; and products produced by this process.