Resin Container, Manufacturing Method of Resin Container, and Manufacturing Apparatus of Resin container

Abstract

In a first embodiment of the present invention, a coating layer 3 which covers a container body 2 is formed; this coating layer 3 disappears while continuously and gradually reducing its thickness in a reduction rate of 0.1 to 1.5 μm/mm from a coating layer forming part 4 toward a coating layer non-forming part 5 ; and the coating layer 3 has a thickness reducing portion 6 in which a thickness reduction rate is 0.1 to 0.5 μm/mm at least in a range of 30 mm in a height direction immediately before a part where the coating layer 3 disappears.

1 . A resin container manufactured by blow molding a parison extruded from an extruder, 
 the resin container comprising at least a container body and a coating layer which covers the whole or a part of the container body,    the coating layer having a thickness reducing portion in which a thickness of the coating layer is successively reduced in a reduction rate of 0.1 to 1.5 μm/mm in a height direction of the container.    
     
     
         2 . The resin container according to  claim 1 , wherein the thickness reducing portion is formed in a range which occupies ¼ or more of a length of a container base portion in a height direction.  
     
     
         3 . The resin container according to one of claims  1  and  2 , wherein the coating layer disappears while reducing a thickness thereof, and the thickness reduction rate of the coating layer is 0.1 to 0.5 μm/mm at least in a range of 30 mm in the height direction immediately before a part at which the coating layer disappears.  
     
     
         4 . The resin container according to one of  claims 1  to  3 , wherein a color tone adjusting layer is provided on an outer surface side of the container body, and the coating layer is formed on an outer surface side of the color tone adjusting layer.  
     
     
         5 . The resin container according to  claim 4 , wherein a direction of a change in thickness of the coating layer along the height direction is opposite to a direction of a change in thickness of the color tone adjusting layer along the height direction at a part where the thickness reducing portion is formed.  
     
     
         6 . The resin container according to one of  claims 1  to  5 , wherein the coating layer and the color tone adjusting layer are formed of the same resin.  
     
     
         7 . The resin container according to one of  claims 1  to  6 , wherein the coating layer and the color tone adjusting layer contain a pearl pigment.  
     
     
         8 . The resin container according to one of  claims 1  to  7 , wherein a container innermost surface includes an inner layer.  
     
     
         9 . The resin container according to one of  claims 1  to  8 , wherein a container outermost surface-includes an outer layer.  
     
     
         10 . The resin container according to one of  claims 1  to  9 , wherein MI of each of a base material resin forming the container body and a sub-material forming the coating layer is 0.1 to 30 g/10 min.  
     
     
         11 . The resin container according to one of  claims 1  to  10 , wherein the coating layer is subjected to coloring which is similar to coloring applied to the container body but has a different color tone.  
     
     
         12 . The resin container according to one of  claims 1  to  10 , wherein the coating layer is subjected to coloring having a hue different from that of coloring applied to the container body.  
     
     
         13 . The resin container according to one of  claims 1  to  12 , wherein the coating layer contains an antibacterial agent.  
     
     
         14 . A manufacturing method of a resin container, comprising: continuously supplying a base material resin forming a container body from a main extruder; 
 discharging from a discharge portion provided in a die head a sub-material supplied from a sub-extruder so that the sub-material joins the base material resin; extruding a parison from a slit portion opened on an end side of the die head; and blow-molding the parison, thereby forming a coating layer which covers the whole or a part of the container body by using the sub-material,    wherein a thickness reducing portion in which a thickness is continuously reduced is formed in the coating layer while adjusting a resin pressure in a supply path of the sub-material fed from the sub-extruder by performing suck-back control which pulls back the sub-material from the discharge portion at an arbitrary timing when joining the sub-material with the base material resin.    
     
     
         15 . The manufacturing method of a resin container according to  claim 14 , wherein the suck-back control is performed at least once before the resin pressure in the supply path of the sub-material is reduced to 70 to 15% of a maximum resin pressure when joining the sub-material with the base material resin.  
     
     
         16 . The manufacturing method of a resin container according to one of claims  14  and  15 , wherein the suck-back control is performed before a reduction rate per unit time of the resin pressure in the supply path of the sub-material becomes 10% or below of a maximum reduction rate.  
     
     
         17 . The manufacturing method of a resin container according to one of  claims 14  to  16 , wherein the reduction rate of the resin pressure in the supply path of the sub-material after the suck-back control is five times or below the reduction rate before the suck-back control.  
     
     
         18 . The manufacturing method of a resin container according to one of  claims 14  to  17 , wherein a direction of a change in thickness of the coating layer is reversed by inverting a top side and a bottom side of a forming mold with respect to an extruding direction of the parison.  
     
     
         19 . A manufacturing apparatus of a resin container, comprising: a main extruder which supplies a base material resin; and a sub-extruder which supplies a sub-material, the sub-material supplied from the sub-extruder being discharged from a discharge portion provided in a die head so that the sub-material joins the base material resin continuously supplied from the main extruder, a parison being then extruded from a slit portion opened on an end side of the die head, the parison being subjected to blow molding, thereby forming a coating layer which covers the whole or a part of a container body formed of the base material resin by using the sub-material, 
 wherein a suck-back mechanism which pulls back the sub-material from the discharge portion is provided between the sub-extruder and the die head, and    the discharge portion is provided in the vicinity of the slit portion in the die head.    
     
     
         20 . The manufacturing method of a resin container according to  claim 19 , wherein a flow path of the sub-material is provided to the die head, the flow path comprising: an annular portion which is formed to relatively approximate the discharge portion as distanced from a side where the sub-material is supplied; and a cone-shaped portion which is continuous with the discharge portion from the annular portion.  
     
     
         21 . The manufacturing method of a resin container according to one of claims  19  and  20 , wherein a second suck-back mechanism is provided at a position close to the die head.  
     
     
         1 . A resin container manufactured by blow molding a parison extruded from an extruder, 
 the resin container comprising at least a container body and a coating layer which covers the whole or a part of the container body,    the coating layer having a thickness reducing portion in which a thickness of the coating layer is successively reduced in a reduction rate of 0.1 to 1.5 μm/mm in a height direction of the container.    
     
     
         2 . The resin container according to  claim 1 , wherein the thickness reducing portion is formed in a range which occupies ¼ or more of a length of a container base portion in a height direction.  
     
     
         3 . The resin container according to one of claims  1 , wherein the coating layer disappears while reducing a thickness thereof, and the thickness reduction rate of the coating layer is 0.1 to 0.5 μm/mm at least in a range of 30 mm in the height direction immediately before a part at which the coating layer disappears.  
     
     
         4 . The resin container according to  claim 1 , wherein a color tone adjusting layer is provided on an outer surface side of the container body, and the coating layer is formed on an outer surface side of the color tone adjusting layer.  
     
     
         5 . The resin container according to  claim 4 , wherein a direction of a change in thickness of the coating layer along the height direction is opposite to a direction of a change in thickness of the color tone adjusting layer along the height direction at a part where the thickness reducing portion is formed.  
     
     
         6 . The resin container according to  claim 1 , wherein the coating layer and the color tone adjusting layer are formed of the same resin.  
     
     
         7 . The resin container according to  claim 1 , wherein the coating layer and the color tone adjusting layer contain a pearl pigment.  
     
     
         8 . The resin container according to  claim 1 , wherein a container innermost surface includes an inner layer.  
     
     
         9 . The resin container according to  claim 1 , wherein a container outermost surface includes an outer layer.  
     
     
         10 . The resin container according to  claim 1 , wherein MI of each of a base material resin forming the container body and a sub-material forming the coating layer is 0.1 to 30 g/10 min.  
     
     
         11 . The resin container according to  claim 1 , wherein the coating layer is subjected to coloring which is similar to coloring applied to the container body but has a different color tone.  
     
     
         12 . The resin container according to  claim 1 , wherein the coating layer is subjected to coloring having a hue different from that of coloring applied to the container body.  
     
     
         13 . The resin container according to  claim 1 , wherein the coating layer contains an antibacterial agent.  
     
     
         14 . A manufacturing method of a resin container, comprising: continuously supplying a base material resin forming a container body from a main extruder; discharging from a discharge portion provided in a die head a sub-material supplied from a sub-extruder so that the sub-material joins the base material resin; extruding a parison from a slit portion opened on an end side of the die head; and blow-molding the parison, thereby forming a coating layer which covers the whole or a part of the container body by using the sub-material, 
 wherein a thickness reducing portion in which a thickness is continuously reduced is formed in the coating layer while adjusting a resin pressure in a supply path of the sub-material fed from the sub-extruder by performing suck-back control which pulls back the sub-material from the discharge portion at an arbitrary timing when joining the sub-material with the base material resin.    
     
     
         15 . The manufacturing method of a resin container according to  claim 14 , wherein the suck-back control is performed at least once before the resin pressure in the supply path of the sub-material is reduced to 70 to 15% of a maximum resin pressure when joining the sub-material with the base material resin.  
     
     
         16 . The manufacturing method of a resin container according to  claim 14 , wherein the suck-back control is performed before a reduction rate per unit time of the resin pressure in the supply path of the sub-material becomes 10% or below of a maximum reduction rate.  
     
     
         17 . The manufacturing method of a resin container according to  claim 14 , wherein the reduction rate of the resin pressure in the supply path of the sub-material after the suck-back control is five times or below the reduction rate before the suck-back control.  
     
     
         18 . The manufacturing method of a resin container according to  claim 14 , wherein a direction of a change in thickness of the coating layer is reversed by inverting a top side and a bottom side of a forming mold with respect to an extruding direction of the parison.  
     
     
         19 . A manufacturing apparatus of a resin container, comprising: a main extruder which supplies a base material resin; and a sub-extruder which supplies a sub-material, the sub-material supplied from the sub-extruder being discharged from a discharge portion provided in a die head so that the sub-material joins the base material resin continuously supplied from the main extruder, a parison being then extruded from a slit portion opened on an end side of the die head, the parison being subjected to blow molding, thereby forming a coating layer which covers the whole or a part of a container body formed of the base material resin by using the sub-material, 
 wherein a suck-back mechanism which pulls back the sub-material from the discharge portion is provided between the sub-extruder and the die head, and    the discharge portion is provided in the vicinity of the slit portion in the die head.    
     
     
         20 . The manufacturing method of a resin container according to  claim 19 , wherein a flow path of the sub-material is provided to the die head, the flow path comprising: an annular portion which is formed to relatively approximate the discharge portion as distanced from a side where the sub-material is supplied; and a cone-shaped portion which is continuous with the discharge portion from the annular portion.  
     
     
         21 . The manufacturing method of a resin container according to  claim 19 , wherein a second suck-back mechanism is provided at a position close to the die head.