Glass syringe barrels with increased cone breaking forces

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 Lbarrel 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 I1 and has an outer diameter d1 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 c1 with an outer radius r1 beginning below the second end of the cone region and a convex and substantially circular arc-shaped area c2 with an outer radius r2 beginning above the second end of the shoulder region, wherein the shoulder region has a glass thickness ns, measured at a point of an inner shoulder surface at which the surface first forms an angle of 30° with the longitudinal axis Lbarrel, and wherein ns 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 d2 and a glass thickness n2;
• 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 Lbarrel 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=P1 and x=P2 for any concave curvature in the interval a minimum value for (1/k(x))/n22 is at least 0.5 mm−1, wherein P1 defines the x-position at which the outer diameter of the glass syringe barrel (100) is 0.95×d2 and P2 is P1+3×n2.