Mould base provided with decompression channels opening on to a peripheral upper face

1. Mold base ( 11 ) to equip a mold ( 1 ) for the manufacturing of a container ( 2 ) by blow molding or stretch blow molding starting from a polyolefin blank, with the container ( 2 ) comprising a body ( 4 ) and a base ( 6 ), the mold base ( 11 ) comprising:

a raised molding face ( 12 ) that defines a base wall ( 13 ) and a peripheral side wall ( 14 ) that extends into the extension of the base wall ( 13 ) and that is connected to the latter by a fillet ( 15 ) that forms an impression for a plane ( 7 ) of installation of the container ( 2 ), with this mold base ( 11 ) ending, opposite the base wall ( 13 ), by a peripheral upper edge ( 16 ),

ribs ( 17 ) forming impressions for reinforcing grooves ( 8 ) of the base ( 6 ) of the container ( 2 ) and that straddle the fillet ( 15 ), and

decompression vents ( 24 ) that are hollowed out in the molding face ( 12 ), wherein the decompression vents ( 24 ) comprise, for each rib ( 17 ):

at least one pair of shallow side channels ( 24 A) that extend on either side of the rib ( 17 ) and that open, at one upper end ( 25 ), onto the peripheral upper edge ( 16 ), and

at least one central channel ( 24 B) that extends into the extension of the rib ( 17 ) and extends from one lower end ( 27 ) located at a vertex ( 28 ) of the rib ( 17 )up to an upper end ( 29 ) by which the central channel ( 24 B) opens onto the peripheral upper edge ( 16 ).

2. Mold base ( 11 ) according to claim 1 , wherein each side channel ( 24 A) has a lower end ( 26 ) that is located at the fillet ( 15 ).

3. Mold base ( 11 ) according to claim 1 , wherein each channel ( 24 A, 24 B) extends to a depth (P) that is less than or equal to 5/10 mm.

4. Mold base ( 11 ) according to claim 3 , wherein the depth (P) of each channel ( 24 A, 24 B) is approximately 3/10 mm.

5. Mold base ( 11 ) according to claim 1 , wherein each channel ( 24 A, 24 B) has a width (L) that is less than or equal to 5/10 mm.

6. Mold base ( 11 ) according to claim 5 , wherein the width (L) of each channel ( 24 A, 24 B) is approximately 3/10 mm.

7. Mold base ( 11 ) according to claim 1 , wherein the side channels ( 24 A) are divergent at their lower ends ( 26 ).

8. Mold base ( 11 ) according to claim 1 , wherein the side channels ( 24 A) are convergent at their lower ends ( 26 ).

9. Mold base ( 11 ) according to claim 1 , wherein each rib ( 17 ) comprises a vertical portion ( 18 ) that extends over the peripheral lateral wall ( 14 ) and a horizontal portion ( 19 ) that extends over the base wall ( 13 ), and wherein the side channels ( 24 A) extend on either side of the vertical portion ( 18 ) for each rib.

10. Mold ( 1 ) for the manufacturing of containers ( 2 ) starting from polyolefin blanks, which comprises a mold base ( 9 ) defining a cavity ( 10 ) hearing the at least partial impression of a body ( 4 ) of the container ( 2 ) and a mold base ( 11 ) according to claim 1 , hearing the at least partial impression of a base ( 6 ) of the container ( 2 ) and that extends into the extension of the mold wall ( 9 ).

11. Mold ( 1 ) according to claim 10 , wherein a gap ( 30 ) is made between a lower end face ( 31 ) of the mold wall ( 9 ) that borders the cavity ( 10 ) and the peripheral upper edge ( 16 ) of the mold base ( 11 ).

12. Mold ( 1 ) according to claim 11 , wherein the gap ( 30 ) has a height (H) that is less than or equal to 5/10 mm.

13. Method for manufacturing a container by blow molding or stretch blow molding in a mold according to claim 10 , which comprises an operation tor inserting a blank into the mold and an operation for injecting a pressurized fluid into the blank.

14. Method according to claim 13 , wherein the blank is manufactured in a polyolefin.

15. Mold base according to claim 2 , wherein each channel extends to a depth that is less than or equal to 5/10 mm.

16. Mold base according to claim 2 , wherein each channel has a width that is less than or equal to 5/10 mm.