Abstract: A spark plug includes a center electrode, an insulator, a metallic shell, and a ground electrode which has a noble metal tip at the other end portion. A gap is formed between a forward end portion of the center electrode and a discharge surface of the noble metal tip. When an acute angle formed by the forward end surface and the discharge surface is ?1, a point on the forward end surface closest to the noble metal tip is A, opposite ends of the discharge surface are B1 and B2, and an angle formed by a first line segment connecting A and B1 and a second line segment connecting A and B2 is ?2, 35°??1?55°, 85°??2?90°, and the difference in length between the first and second line segments is equal to or less than 10% of the longer line segment.

Abstract: A spark plug includes a center electrode, an insulator, a metallic shell, and a ground electrode which has a noble metal tip at the other end portion. A gap is formed between a forward end portion of the center electrode and a discharge surface of the noble metal tip. When an acute angle formed by the forward end surface and the discharge surface is ?1, a point on the forward end surface closest to the noble metal tip is A, opposite ends of the discharge surface are B1 and B2, and an angle formed by a first line segment connecting A and B1 and a second line segment connecting A and B2 is ?2, 35°??1?55°, 85°??2?90°, and the difference in length between the first and second line segments is equal to or less than 10% of the longer line segment.

Abstract: A resin composition having superior molding character, bonding character, moisture resistance, and heat resistance, for encapsulating of a semiconductor which contains:(a) An ether imide group compound represented by the general formula (I) ##STR1## wherein, each of R.sup.1 -R.sup.4, R.sup.8 and R.sup.8 is hydrogen, lower alkyl group, lower alkoxy group, lower fluoroalkyl group, chlorine or bromine, and R.sup.1 -R.sup.4, R.sup.7 and R.sup.8 may be same or different each other, and each of R.sup.5 and R.sup.6 is hydrogen, methyl group, ethyl group, trifluoromethyl group or trichloromethyl group, and R.sup.5 and R.sup.6 may be same or different each other, and D is a hydrocarbon group of a dicarboxylic acid having an ethylene type unsaturated double bond of an extract of the compound obtained by extraction with water in an amount 10 times by weight of the compound at 120.degree. C. for more than 100 hours has electric conductivity of at most 300 s/cm ph of 1.

Abstract: A polymer having dihydropyridine rings or dihydrotriazine rings as main constitutional units, an ethynyl- or cyanato-terminated Schiff's compound which is a starting material for producing the polymer, and applications of the polymer.

Abstract: There are disclosed a nitrile-terminated Schiff compound represented by the formula X--Z--Y--C.tbd.N).sub.m (I) wherein n is 1 or 2, Z is --CH.dbd.N-- or --N.dbd.CH-- and Y is a divalent organic group such as phenylene and the like, and X is the same as Y when n=2 or H, lower alkyl group etc. when n=1; polymers obtained by polymerizing said Schiff compound alone or together with other monomers, and a process for preparing such a polymer therefrom.

Abstract: Disclosed is a resin encapsulated semiconductor memory device comprising a semiconductor memory element, a package encapsulating the memory element and an .alpha.-rays shielding layer made from a water-resistant aromatic polyimide polymer, interposed between the memory element and the package, the aromatic polyimide polymer having a saturated water absorption rate of 1% or less. The polyimide polymer is exemplified as the polymer having the following recurring units: ##STR1## wherein R is an aliphatic or aromatic group; R.sub.1 and R.sub.2 are independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or CF.sub.3 ; and R.sub.3 to R.sub.6 are independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 4 carbon atoms. The disclosure is also concerned with resin encapsulated semiconductor devices in which the aromatic polyimide polymer of low water absorption is used as an insulating layer or passivation film.

Abstract: A SF.sub.6 gas insulating electric apparatus usable as a circuit breaker, etc., containing a SF.sub.6 gas insulator and a resin insulator, both of which insulators are present in an atmosphere to be exposed to arcs, characterized by making at least the surface portion to be exposed to arcs of the resin insulator from a polymer containing nitrogen atoms or a polyolefin resin, and if necessary together with an inorganic filler powder, is excellent in both surface and inner arc resistance and can maintain breaking performance for a long period of time.

Abstract: In a semiconductor memory device comprising semiconductor memory elements having such a degree of integration in memory circuits as to produce soft errors by incident .alpha.-rays derived from a packaging material and a package which packages the memory elements and is made from the packaging material, when an .alpha.-rays shielding layer made from a resinous material, which may contain one or more high-purity fillers, containing a total amount of 1 part per billion or less of uranium and thorium is interposed between the memory elements and the package, the generation of soft errors is reduced remarkably.

Abstract: An ether imide of the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and D are as defined in the specification produced by reacting a diamine with an ethylenically unsaturated dicarboxylic acid can give a composition together with one or more unsaturated polyesters, epoxy compounds, amines, and the like to give shaped articles excellent in flexibility and heat resistance.

Abstract: The disclosure is concerned with a maleimide-diamine resin composition which is well soluble to a low boiling point solvent and is excellent in heat resistance. The composition is featured by containing a maleimide-diamine adduct having the general formula: ##STR1## wherein A is a mono-, di-, tri- or tetravalent organic group containing at least two carbon atoms, R.sub.1 through R.sub.6 are hydrogen atom, a lower alkyl group, a lower alkoxy group, chlorine atom, bromine atom, trifluoromethyl group, or trichloromethyl group, and m is an integer of 0-4.

Abstract: A bisimide-ether compound having the general formula is obtained by reacting an ethylenically unsaturated dicarboxylic acid anhydride, a diamine compound and a phenolic compound having in the molecule at least two hydroxyl groups, or by reacting a prepolymer of the anhydride and diamine compound with the phenolic compound: ##STR1## wherein R.sub.1 is a group containing at least two carbon atoms, R.sub.2 is a group containing at least two carbon atoms, R'.sub.2 is a group containing at least two carbon atoms and a carbon-carbon double bond, R.sub.3 is an aromatic group, the nitrogen atoms of the imide rings being directly connected to different carbon atoms of the group R.sub.1, the carbonyl groups of the imide rings being directly connected to different carbon atoms of the group R.sub.2 or R'.sub.2, the oxygen atoms between the groups R.sub.2 and R.sub.3 being directly connected to an aromatic nucleus of the group R.sub.3, and n is an integer of zero, one or more than 1.

Abstract: A thermosetting resin composition suitable for use as a molding material comprising (a) a reaction product mixture obtained by preferably reacting 1 mole of a dicarboxylic acid anhydride having ethylenic carbon-carbon double bond such as maleic anhydride with 2-20 moles of a diamine such as 4,4'-diaminodiphenylmethane in a molten state and (b) an epoxy compound having more than one 1,2-epoxy group on the average gives a cured product excellent in heat resistance, etc., when cured with heating at a temperature of 150.degree. to 200.degree. C.

Abstract: An unsaturated polyester resin composition for use in pressure molding, which comprises an unsaturated polyester resin and fillers consisting essentially of (a) calcium carbonate powder which passes a 325 mesh sieve, (b) an inorganic mineral particulate which passes a 12 mesh sieve and is retained on a 200 mesh sieve and (c) glass fibers having a length larger than 0.2 mm, wherein the ratio by weight of (a) to (b) is within a range of from 0.3 to 10, the ratio of (a)+(b) to the unsaturated polyester resin is within a range of from 1.5 to 7, and the ratio of (c) to the total weight of the resin, calcium carbonate, silica sand and glass fiber is within a range of from 0.01 to 0.25.

Abstract: A polymerizable, curable resin composition suitable for molding materials, prepreg, powdery paint materials or the like, which comprises a polyepoxide, a uretdione and a tetraphenyl borate-amine complex. This composition has long pot life and good curability by virtue of latent catalytic characteristics of the complex.

Abstract: In a dynamoelectric machine having a stator assembly of coil windings and a core, a heat-dissipating, electro-insulative housing encapsulates the coil windings and the core. The housing is made of a cured molded article or material formed of a resin-filler composition which comprises a liquid unsaturated polyester resin, a finely divided calcium carbonate powder, an inorganic mineral particulate having a particle size larger than that of the calcium carbonate powder, and a chopped glass fiber, wherein the ratio by weight of the calcium carbonate to the mineral particulate is 0.3 to 4, the ratio of the weight of glass fiber to the total weight of the composition is 0.05 to 0.25, the ratio of the weight of the polyester resin to the total weight of the composition is 0.1 to 0.4 and the weight ratio of the calcium carbonate powder, the mineral particulate and the glass fiber to the total weight of the composition is 0.6 to 0.9.

Abstract: A novel thermosetting resin composition consisting essentially of (a) an isocyanate group-terminated condensate obtained by reacting a polycarboxylic acid compound having at least one acid anhydride ring with a stoichiometrical excess of a polyfunctional isocyanate compound or said condensate containing the unreacted isocyanate compound, (b) a polyfunctional epoxy compound and (c) a catalyst which forms mainly isocyanurate rings and oxazolidone rings. A cured product having excellent thermal resistance and excellent high temperature strength can be obtained by heating said composition.

Abstract: An epoxy resin composition having a remarkably improved storage stability and an excellent hardening characteristic when heated, which comprises an epoxy resin and an aromatic amino carboxylic acid or a derivative thereof as a hardener for the epoxy resin. This composition can be molded by injection molding, heretofore being deemed inapplicable to epoxy resin compositions, whereby the molded articled of epoxy resin can be produced with a high molding efficiency.