Patent GB-674562-A (GB)
Title: Ampul with breakable neck
Inventor: SMITH WINFIELD FOULDS
IPC: A61J1/06
Filed: 1950-07-04
Abstract: 674,562. Combining glasses of different compositions. OWENS-ILLINOIS GLASS CO. July 4, 1950, No. 16660/50. Class 56. [Also in Group VI] A relatively small localised area B' of a glass container A is coated with a solidified fusible material which is fused to the glass in that area, the coating material having a coefficient of expansion greater than that of the glass whereby an initial force is set up in the vicinity of the localised area which is less than that required to effect complete fracture of the glass. This defined area of the glass is therefore of greater frangibility. The coating material preferably includes colouring matter such as the salts of Co, Cr, Ti, Sb &c. but may be of the same colour as the glass when it is denoted by the difference in contour. The coating is applied as a frit and is heated to a temperature sufficient to melt the frit but below the melting point of the container. The softening point of the coating is usually 450- 600‹ C. and the fusion temperature 500-600‹ C. After cooling the coating is under tension, since it has the greater contraction rate, this tension being controlled by selecting a glass and coating with the desired contraction rates, and only a slight further pressure is required to fracture the container. Suitable compositions for the container in percentages by weight are, (A) SiO, 74.7, B 2 O 3  9.6, Al 2 O 3  5.6, ZnO 0.1, CaO 0.9, Na 2 O 6.4, K,O 0.5, Sb,O, 0.009, BaO 2.2, As 2 O 5  0.027, (B) SiO, 65.2, B 2 O 3  5.0, Al 2 O 3  2.4, ZnO 5.4, MgO 1.6, CaO 2.6, Na 2 O 9.1, K,O 0.8, Sb,O, 0.6, Fe 2 O 3  3.3, MnO 4.0, (C) SiO, 67.6, B,O, 1.5, Al 2 O 3  2.8, MgO 4.0, CaO 5.6, Na 2 O 15.1, K,O 1.3, BaO 1.9, (D) Al 2 O 3  18.0, ZnO 10.0, P 2 O 5  72.0, and (E) SiO 2  68.3, B 2 O 3  2.2, Al 2 O 3  2.0, ZnO 6.8, MgO 0.1, CaO 5.7, Na 2 O 14.5, K,O 0.4. The properties of these glasses are respectively, coefficient of expansion 50 x 10-', 69 x 10-', 92 x 10-', 59 x 10-', 88 x 10-', softening temperature 653‹ C., 612‹ C., 590‹ C., 675‹ C., 600‹ C., and annealing temperature 575‹ C., 548‹ C., 520‹ C., 605‹ C., 536‹ C. Suitable coating compositions in weight percentages are, (a) SiO, 27.9, B,O, 4.2, Al 2 O 3  1.3, TiO 2  12.5, PbO 48.8, CaO plus MgO 0.16, Na 2 O 2.9, K,O 0.19, Li 2 O 0.73, As 2 O 5  0.58, (b) SiO 2  27.2, B 2 O 3  2.9, Al 2 O 3  0.84, ZnO 2.3, PbO 51.0, CaO plus MgO 0.17, Na,O 1.08, K,O 0.22, S 0.86, Cr 2 O 3  5.6, CoO 1.2, CdO 7.2, As 2 O 5  0.1, and (c) lead chloride consisting of Pb 74.5 per cent and Cl 2  25.5 per cent, with coefficients of expansion (a) 86Î10<SP>-7</SP>, (b) 73Î10<SP>-7</SP>, and softening temperatures (a) 463‹ C., (b) 484‹ C., and '(c) 501‹ C. The force required to break glass (A) coated with coating (a) is 58 per cent less than that required to break uncoated glass (A), similarly the reduction when (D) is coated with (a) is 44 per cent, (B) coated with (b) 15 per cent, and (E) coated with (a) 11 per cent. The minimum weakening should be about that which gives an 11 per cent lesser breaking force. The coating may be applied over a small area or along a line if necessary around the major or entire portion of the circumference.