Glass syringe barrels with increased cone breaking forces
A glass syringe barrel is provided that has an at least partially conically shaped upper portion and a longitudinal axis. The glass syringe barrel has a top end through which a liquid can be ejected and a bottom end into which a plunger stopper can be pushed. The glass syringe barrel includes, in a direction from the top end to the bottom end, a cone, a shoulder region, and a body region. The shoulder region has and outer contour that has a concave and substantially circular arc-shaped area c 1 with an outer radius r 1 . The outer contour of the glass syringe barrel in the shoulder region is defined by a certain minimum value the radius of curvature.
1. A glass syringe barrel, comprising:
a top end through which a liquid can be ejected;
a bottom end into which a plunger stopper can be pushed;
a longitudinal axis L barrel through the top and bottom ends; and
a cone region having a first end that corresponds to the top end and a second end, the cone region has a length I 1 and has an outer diameter d 1 at the second end;
a shoulder region having a first end that is adjacent to the second end of the cone region and a second end, wherein the shoulder region has an outer contour that comprises a concave and substantially circular arc-shaped area c 1 with an outer radius r 1 beginning below the second end of the cone region and a convex and substantially circular arc-shaped area c 2 with an outer radius r 2 beginning above the second end of the shoulder region; and
a body region having a first end that is adjacent to the second end of the shoulder region and a second end that corresponds to the bottom end, wherein the body region has an outer diameter d 2 and a glass thickness n 2 ,
wherein the outer contour consists of a local curvature configured so that a maximum tensile stress in a transition region between the shoulder region and the cone region, when a force of 100 N is applied onto the cone, is at least 8% less than a comparative glass syringe barrel without the local curvature, and
wherein, if an outer surface of the body region is placed on a plane horizontal substrate, within any given cross-section of the glass syringe barrel that is located in a plane centrically located in the glass syringe barrel and comprising the longitudinal axis L barrel of the glass syringe barrel, a first function ƒ(x) defines a vertical distance between the substrate and the outer surface at a given position x,
k ( x )=| f ( x )/[1+ f ( x ) 2 ] 3/2 |
defines an absolute value of the curvature of ƒ(x) at a given position x, and in an interval between x=P 1 and x=P 2 for any concave curvature in the interval a minimum value for (1/k(x))/n 2 2 is at least 0.5 mm −1 , wherein P 1 defines the x-position at which the outer diameter of the glass syringe barrel ( 100 ) is 0.95×d 2 and P 2 is P 1 +3×n 2 .
2. The glass syringe barrel of claim 1 , wherein (1/k(x))/n 2 2 is at least 0.6 mm −1 .
3. The glass syringe barrel of claim 1 , wherein in the interval between x=P 1 and x=P 2 the maximum value of the first derivative ƒ(x) max of ƒ(x) is less than 18.
4. The glass syringe barrel of claim 3 , wherein the maximum value of the first derivative ƒ(x) max of ƒ(x) is less than 15.
5. The glass syringe barrel of claim 1 , wherein the outer radius n 1 is in a range from 0.5 to 3 mm.
6. The glass syringe barrel of claim 1 , wherein outer radius r 2 is in a range from 1.2 to 3.1 mm.
7. The glass syringe barrel of claim 1 , further comprising a constriction region that is located between the cone region and the shoulder region, the constriction region having a first end that is adjacent to the second end of the cone region, a second end that is adjacent to the first end of shoulder region and an outer contour c 3 , wherein the constriction region has a length 11 , a minimum outer diameter d 1 ′<d 1 below the first end of the constriction region and an outer diameter d 1 ″ at the second end of the constriction region.
8. The glass syringe barrel of claim 7 , wherein the outer contour c 3 in the constriction region is conically shaped with d 1 ′<d 1 ″ and wherein at the second end of the constriction region, the outer contour c 3 in the constriction region merges into area c 1 without any offset.
9. The glass syringe barrel of claim 8 , wherein in the constriction region a first line that runs parallel to the longitudinal axis L barrel and a second line that runs parallel to the outer contour c 3 and that runs in the same plane as the first line include an angle γ, wherein γ is in the range from 0.3 to 2.5°.
10. The glass syringe barrel of claim 1 , wherein 11 is in a range from 8 to 12 mm.
11. The glass syringe barrel of claim 7 , wherein 11 is in a range from 1 to 3 mm.
12. The glass syringe barrel of claim 1 , wherein n 2 is in the range from 0.6 to 1.6 mm.
13. The glass syringe barrel of claim 1 , wherein at least a part of the outer surface of glass syringe barrel in the cone region is roughened or is provided with a coating.
14. The glass syringe barrel of claim 1 , further comprising a tip cap attached to the top end.
15. A syringe comprising the glass syringe barrel of claim 1 and a plunger stopper in the bottom end.
16. A syringe, comprising:
the glass syringe barrel of claim 1 ; and
a pharmaceutical composition in an inner volume of the glass syringe barrel.
17. A plurality of glass syringe barrels, each of the glass syringe barrels comprising:
a top end through which a liquid can be ejected;
a bottom end into which a plunger stopper can be pushed;
a longitudinal axis L barrel through the top and bottom ends; and
a cone region having a first end that corresponds to the top end and a second end, the cone region has a length I 1 and has an outer diameter d 1 at the second end;
a shoulder region having a first end that is adjacent to the second end of the cone region and a second end, wherein the shoulder region has an outer contour that comprises a concave and substantially circular arc-shaped area c 1 with an outer radius r 1 beginning below the second end of the cone region and a convex and substantially circular arc-shaped area c 2 with an outer radius r 2 beginning above the second end of the shoulder region, wherein the shoulder region has a glass thickness n s , measured at a point of an inner shoulder surface at which the surface first forms an angle of 30° with the longitudinal axis L barrel , and wherein n s is in the range from 1.2 to 2 mm;
a body region having a first end that is adjacent to the second end of the shoulder region and a second end that corresponds to the bottom end, wherein the body region has an outer diameter d 2 and a glass thickness n 2 ; and
a 50% quantile of the glass syringe barrels contained in the plurality of glass syringe barrels have a Luer cone breaking resistance of at least 145 N,
wherein, if an outer surface of the body region is placed on a plane horizontal substrate, within any given cross-section of the glass syringe barrel that is located in a plane centrically located in the glass syringe barrel and comprising the longitudinal axis L barrel of the glass syringe barrel, a first function ƒ(x) defines a vertical distance between the substrate and the outer surface at a given position x,
k ( x )=| f ( x )/[1+ f ( x ) 2 ] 3/2 |
defines an absolute value of the curvature of ƒ(x) at a given position x, and in an interval between x=P 1 and x=P 2 for any concave curvature in the interval a minimum value for (1/k(x))/n 2 2 is at least 0.5 mm −1 , wherein P 1 defines the x-position at which the outer diameter of the glass syringe barrel ( 100 ) is 0.95×d 2 and P 2 is P 1 +3×n 2 .
18. The plurality of the glass syringe barrels of claim 17 , further comprising a 1% quantile of the glass syringe barrels contained in the plurality of glass syringe barrels have a Luer cone breaking resistance of at least 50 N.
19. The plurality of the glass syringe barrels of claim 18 , wherein the plurality comprises at least 10 glass syringes.