Abstract: A fluororesin composition containing a melt moldable fluororesin and a silica, wherein the fluororesin has 25 or more carbonyl group-containing functional groups per 106 main-chain carbon atoms; the silica is a spherical silica; and the fluororesin composition has a linear expansion coefficient of 100 ppm/° C. or lower. Also disclosed is a fluororesin sheet including the fluororesin composition, a laminate including a copper foil layer and a layer including the fluororesin composition and a substrate for circuits including a copper foil layer and a layer including the fluororesin composition.

Abstract: A device to duplicate a key utilizing the predetermined pitch codes and depth codes of the key to be duplicated, wherein a punch which produces an individual pattern of serrations and a die which makes a pair with said punch are used, a key-holding means which clamps a blank key to be duplicated is moved to the specified position by the use of a pitch code plate and either a depth code plate provided with stair-like codes corresponding respectively to the depth code of the key to be duplicated or a depth code piece whose contacting faces have the width corresponding respectively to the depth code of the key to be duplicated and, by the use of aforesaid punch and die, an individual serration pattern is formed one by one on the blank key mounted on the device.

Abstract: A key having a gripping portion made of synthetic resin and a metal made base end portion is provided with an insertion portion covered with a synthetic resin. The insertion portion is made thin, and the gripping portion made of synthetic resin covers the corresponding insertion portion. A reinforcement portion having a thickness which is the same as that of the blade portion, but having a width which is wider than the width of the blade portion is provided at a middle portion between the insertion portion and the blade portion on which key serrations are formed. The key is not bulky in size and can not be damaged even after repeated uses.

Abstract: A key using a synthetic resin bow which is connected to a metal key body having a blade section to which serrations are to be formed for use and an inserting section which is thinner than the blade section; the bow is formed into the thickness within 0.9 to 1.3 times that of the blade section.