Check valve, manufacturing method thereof and container having check valve

Abstract

In order to provide a check valve capable of sufficiently suppressing the mixing of air into the container even if a certain impact is applied to the container and also capable of stably maintaining good pouring of the content, a check valve 10 of the invention is formed of rubber material and manufactured by integral molding. The check valve 10 has a tubular main body 1 having openings 1 a and 1 b at opposite ends, a lid 3 arranged to close one opening 1 a of the main body 1 , and a hinge 5 that connects the main body 1 and the lid 3 . The lid 3 has a projection 3 a on the side surface 3 b , the projection 3 a coming in contact with a peripheral edge of the opening 1 a of the main body 1.

1 . A check valve formed of rubber material and manufactured by integral molding, comprising:
 a tubular main body having openings at opposite ends;   a lid arranged to close one opening of the main body; and   a hinge that connects the main body and the lid and is adapted to open the one opening when force is applied to the lid outwardly from the main body side,   wherein the lid has a projection on a side surface thereof, the projection coming in contact with a peripheral edge of the one opening of the main body.   
     
     
         2 . The check valve according to  claim 1 , wherein the one opening is constituted by a linear portion which serves as the hinge and an arc-shaped portion. 
     
     
         3 . The check valve according to  claim 2 , wherein an outer diameter R 1  of an arc-shaped portion of the lid is greater than a diameter R 2  of the arc-shaped portion of the opening and wherein the difference between R 1  and R 2  is from 0.06 mm to 0.50 mm. 
     
     
         4 . The check valve according to  claim 3 , wherein the side surface of the lid and an inner surface of the main body form an angle of 15-25 degrees. 
     
     
         5 . The check valve according to  claim 4 , wherein the rubber material has a hardness of 30-80 degrees and an elongation of 200-900%. 
     
     
         6 . A container comprising:
 a container main body formed of a film; and   a check valve according to  claim 1 , which is attached to the container main body.   
     
     
         7 . The container according to  claim 6 , further comprising a spout in which the check valve is mounted. 
     
     
         8 . The container according to  claim 7 , wherein a liquid outlet at a tip of the spout is shaped to be narrowed in the middle and again broadened. 
     
     
         9 . The container according to  claim 8 , wherein at least part of the main body of the check valve is formed to be thin enough to be able to deform according to a difference from atmospheric pressure when the check valve has a negative pressure inside and thereby allow the check valve to have a reduced volume. 
     
     
         10 . The container according to  claim 9 , wherein the main body of the check valve has a stepped form composed of a small diameter part and a large diameter part and the one opening is formed at the small diameter part. 
     
     
         11 . The container according to  claim 10 , wherein the small diameter part is formed to be thinner than the large diameter part. 
     
     
         12 . A method for manufacturing a check valve which comprises: a tubular main body having openings at opposite ends; a lid arranged to close one opening of the main body; and a hinge that connects the main body and the lid and is adapted to open the one opening when force is applied to the lid outwardly from the main body side, the lid having a projection on a side surface thereof, the projection coming in contact with a peripheral edge of the one opening of the main body, the method comprising:
 a molding step of obtaining a molded body of rubber material in a cavity having a concave portion to form the projection, the rubber material having a hardness of 30-80 degrees and an elongation of 200-900%;   a mold-releasing step of removing the molded body from the cavity; and   a cutting step of separating the main body and the lid from each other except a portion serving as the hinge.