Abstract: An apparatus for introducing a pressurized gas includes a pressurized-gas supply-source, a plurality of measuring tanks, a first pressurized-gas supply-line, pressurized-gas supply valves in the first pressurized-gas supply-line, second pressurized-gas supply-lines and pressurized-gas discharge-control valves disposed in the second pressurized-gas supply-lines. A combination of the measuring tanks is determined on the basis of the amount of a pressurized gas required for forming a hollow portion in a molded article, and the pressurized-gas discharge-control valves disposed in the second pressurized-gas supply-lines are controlled on the basis of the above determination.

Abstract: A light guide plate which is made of a transparent resin and has a first main surface and a second main surface opposite to said first main surface, said first main surface having a surface portion provided with convex portions having a height of 5×10?7 m to 6×10?5 m each and a pitch of 5×10?7 m to 4×10?4 m, each convex portion having a tip portion, and the convex portions of at least 80% of the total convex portions having the tip portions having a radius of curvature of 2×10?6 m or less.

Abstract: A light guide plate which is made of a transparent resin and has a first main surface and a second main surface opposite to said first main surface, said first main surface having a surface portion provided with convex portions having a height of 5×10?7 m to 6×10?5 m each and a pitch of 5×10?7 m to 4×10?4 m, each convex portion having a tip portion, and the convex portions of at least 80% of the total convex portions having the tip portions having a radius of curvature of 2×10?6 m or less.

Abstract: A light guide plate made of a transparent resin includes a first main surface and a second main surface opposite to the first main surface. The first main surface has a surface portion provided with convex portions having a height in the range of 5×10?7 m to 6×10?5 m each and a pitch in the range of 5×10?7 m to 4×10?4 m. The light guide plate having tip portions of at least 80% of the total convex portions with a radius of curvature of 2×10?6 m or less, or the surface of the convex portions having a surface roughness of 3×10?7 m or less.

Abstract: An apparatus for introducing a pressurized gas comprises a pressurized-gas supply-source 10, a plurality of measuring tanks 20A, 20B and 20C, a first pressurized-gas supply-line 30, pressurized-gas supply valves 31A, 31B and 31C somewhere in the first pressurized-gas supply-line 30, second pressurized-gas supply-lines 32 and pressurized-gas discharge-control valves 33A, 33B and 33C disposed somewhere in the second pressurized-gas supply-lines 32, in which a combination of the measuring tanks 20A, 20B and 20C is determined on the basis of the amount of a pressurized gas required for forming a hollow portion in a molded article, and the pressurized-gas discharge-control valves 33A, 33B and 33C disposed in the second pressurized-gas supply-lines 32 are controlled on the basis of the above determination.

Abstract: A light guide plate which is made of a transparent resin and has a first main surface and a second main surface opposite to said first main surface, said first main surface having a surface portion provided with convex portions having a height of 5×10−7 m to 6×10−5 m each and a pitch of 5×10−7 m to 4×10−4 m, each convex portion having a tip portion, and the convex portions of at least 80% of the total convex portions having the tip portions having a radius of curvature of 2×10−6 m or less.

Abstract: A method for the production of a molded article having a hollow portion by utilizing a gas compression apparatus having a gas source, a compressor composed of a piston and a cylinder, and a discharge valve for controlling the flow of pressurized gas discharged from the cylinder, the method comprising introducing the pressurized gas through the discharge valve into a molten resin injected into a cavity of a mold, under the control of the discharge valve while carrying out, in one molding cycle, the intake step of supplying gas from the gas source to the cylinder and the compression step of compressing the gas by movement of the piston in the cylinder, at least twice each on the basis of predetermined compressor operation conditions, and thereby forming the hollow portion in the molded article.

Abstract: An injection-molding method using an injection molding machine having a mold apparatus comprising(A) a fixed mold member,(B) a movable mold member movable in the mold opening and closing directions,(C) an intermediate mold member which is provided between the fixed mold member and the movable mold member and is slidable in the mold opening and closing directions between the fixed mold member and the movable mold member, and(D) at least one intermediate mold member sliding means for sliding the intermediate mold member in the mold opening and closing directions,the method including the steps ofinjecting a molten resin into a cavity formed of cavity wall surfaces of the fixed mold member, the intermediate mold member and the movable mold member, andincreasing the distance of the cavity by moving the movable mold member in the mold opening direction with keeping the intermediate mold member in intimate contact with the fixed mold member or the movable mold member by the intermediate mold member sliding means, an

Abstract: A process for the production of a molded article having a hollow structure, using an injection molding machine equipped with a mold apparatus having a mold provided with a cavity, said process comprising the steps of(a) positioning a plug in its forward end position in the cavity with a plug-moving means before a molten resin is injected,(b) moving the plug toward its backward end position nearly in parallel with a flow-axis direction of the molten resin, with the plug-moving means or under a pressure of the injected molten resin, after the injection of the molten resin is initiated,(c) introducing a pressurized fluid into the molten resin in the cavity through a pressurized fluid introducing portion while the plug is moving, and(d) moving the plug up to its backward end position nearly in parallel with the flow-axis direction of the molten resin with the plug-moving means or under the pressure of the molten resin and/or the pressurized fluid introduced into the molten resin, and then, cooling and solidifying

Abstract: A gas-feeding nozzle is to be used with a mold attached to an injection molding machine and for introducing a pressurized gas into molten resin injected in a cavity of the mold to produce an injection molded article having a hollow structure. A top forward portion of the gas-feeding nozzle is formed of a gas ejection portion having an inner side wall, along a direction of flow of the pressurized gas, having at least one concavo-convex portion.

Abstract: A gas-feeding device as follows:(A) a gas-feeding nozzle and(B) gas-feeding nozzle shifting device for putting a top portion of the gas-feeding nozzle in forward and backward movement in a guide portion which is provided in a mold and communicates with a cavity and an outside of the mold,the gas-feeding device being used for feeding a pressurized gas through the gas-feeding nozzle into a molten resin injected into the cavity of the mold attached to an injection molding machine for producing a molded article having a hollow portion,wherein:a clearance is provided between the top portion of the gas-feeding nozzle and the guide portion, andat least part of the top portion of the gas-feeding nozzle is out of contact with the guide portion when the molten resin is injected into the cavity.

Abstract: A gas-feeding nozzle 10 for use in a mold 42 attached to an injection molding machine and for introducing a pressurized gas into a molten resin 60 injected into the cavity 48 of the mold, for producing a molded article having a hollow structure, the gas-feeding nozzle 10 comprising a non-return valve 12 provided at an outlet end of the gas-feeding nozzle 10 and a mechanism 14 for preventing the inflow of molten resin, the mechanism is provided upstream to the non-return valve 12 in the flow direction of the pressurized gas.

Abstract: A drive apparatus for driving a movable member of a plastic molding die apparatus is provided which drives and controls a movable shaft for holding a gas injection nozzle by using a plurality of cylinders so that the gas injection nozzle of the die apparatus for use in a gas injection molding method can easily be changed. Resin is supplied from a position through a second die into a cavity formed between a first die and the second die, the drive apparatus disposed adjacent to the first die is used to drive the movable shaft for holding the nozzle of a gas supply means to supply gas into the resin in the cavity so that a hollow product is molded. The nozzle of the gas supply means is disposed at the leading portion of the hollow movable shaft.

Abstract: An injection-molded article of a thermoplastic resin having a base body defining an outer shape of the injection-molded article, a thick-wall portion rising from the base body, and a foot portion formed on the base body and at a foot of the thick-wall portion, the foot portion rising from the base portion, having a thickness which gradually increases toward the thick-wall portion, and having a (maximum thickness of the foot portion)/(width extending from the thick-wall portion to an end of the foot portion) ratio of 1/40 to 1/2, at least the thick-wall portion having a hollow portion.

Abstract: A method for producing a handle-shaped molded article (1) having a thick grip portion (2) and at least one thick fitting portion (3) by injection molding using an injection molding apparatus (10) equipped with a mold having a cavity (60), a resin gate (46) provided in a portion (62) where the fitting portion is to be formed and a gas inlet (48) provided in a portion (64) where the grip portion is to be formed. A hollow structure (4) is formed in the grip portion (2) and a solid structure is formed in the fitting portion (3) by injecting a molten resin into the cavity (60) through the resin gate (46), thereby filling molten resin in a fitting portion-forming cavity zone formed of that portion (62) of the mold where the resin gate is provided and the fitting portion is to be formed and further filling molten resin in part of the rest of the cavity.

Abstract: A gas injection technique of injecting an inert gas (e.g., nitrogen gas) into a molten resin in a cavity, involves utilizing the strokes of reciprocation of a piston in the compression cylinder are used in a series mode, to perform a two-stage compression within the same cylinder, thereby providing a high-pressure gas. The method can also include establishing a relationship or pattern of the amount of movement of the piston with the speed of movement of the piston established to provide optimum control of the relationship between the pressure generated and piston stroke, and quantity of gas injected. The injecting gas pressure can be detected, to control a hold pressure, or the relationship between a piston stroke and generated pressure, so as to obtain optimal injecting pressure during the injection molding operation.