Vial and method for producing the same

Abstract

A method for producing a vial with low alkali elution by removing a deteriorated region caused by processing on an internal surface of a vial is disclosed. The method involves forming vials from borosilicate glass tubes including a first step of forming a borosilicate glass tube into a cup-shaped body by formation of a bottom of a vial, and a second step of forming the cup-shaped body into the vial by formation of a mouth of the cup-shaped body.

Claims

1. A method for producing a vial as a product wherein the method comprises the steps of: providing as a preform a container for the vial having a bottom made of a borosilicate glass tube, and intensely heating only an inner surface of the container as the preform with oxygen-gas flame such that the flame changes from an early blue flame to a yellow flame with increasing temperature so as to obtain the vial as the product.

2. The method according to claim 1 wherein the step of intensely heating is carried out such that a flame reaction of sodium present in the container as the preform of the borosilicate glass tube is caused.

3. The method according to claim 2, wherein the inner surface to be intensely heated is present from a bottom toward an opening of the container by a certain distance where a deteriorated region caused by forming is present.

4. The method according to claim 1 wherein the oxygen-gas flame is oxygen-town gas flame.

5. The method according to claim 1 wherein the oxygen-gas flame is produced by a point burner.

6. The method according to claim 1, wherein the inner surface to be intensely heated is present from a bottom toward an opening of the container by a certain distance where a deteriorated region caused by forming is present.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an electron microscope photograph of a deteriorated region affected by processing of a cup C according to the present invention, and

(2) FIG. 2 is an electron microscope photograph showing a deteriorated region affected by processing of a cup C according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(3) The inventors have found that, when the forming steps in the process of forming borosilicate glass tube into a vial are carried out in the order of bottom-forming to mouth-forming, the quantity of eluted alkali is reduced to one-fifth to one-sixth of that of the vial formed by the conventional process proceeding from mouth-forming to bottom-forming. In the conventional process proceeding from mouth forming to bottom forming, alkali-containing materials exuded from or vaporized from the glass at the time of bottom forming are trapped in the vial-in-process because of a narrowed mouth of the vial-in-process, resulting in formation of the deteriorated region due to processing. In contrast, in the process proceeding from bottom forming to mouth forming, it is believed that the vaporized materials are easily released from the vial-in-process to the outside because of a large opening of the vial-in-process, resulting in decrease in formation of the deteriorated region due to processing, which in turn causes lowering of the alkali elution. When the borosilicate glass is intensely heated by an oxygen-gas flame of the point burner, the flame changes from an early blue flame to a yellow flame with increasing temperature. This results from the flame reaction of sodium (Na) present in the glass. Based on these observations, the inventors have found that use of fire-blasting with a sharp and strong oxygen-gas flame makes it possible to remove the deteriorated region induced by processing in the internal surface of the vial. It is believed that the fire-blasting is shot-blasting with particle ions and molecules in the flame.

(4) In order to remove the processing-induced deteriorated region by fire-blasting, it is required to allow the oxygen-gas flame jet from the point burner to flow out with little resistance after impingement on the inner surface of the glass tube. To this end, the vial forming process is required to begin with forming of a bottom to make a glass tube into a cup-shaped body and then proceed to forming of a mouth. It should be noted that the quantity of eluted alkali for evaluation of effects of the forming process according to the present invention was determined as an amount (mL) of 0.01 mol/L sulfuric acid consumed in accordance with Method 2 (internal surface method) defined in the Japanese Pharmacopoeia.

Example 1

(5) Using the conventional process (mouth-forming to bottom-forming process), there were produced vials with 60 mm-height12.5 mm-internal mouth diameter (Vial P) from borosilicate glass tubes with a 30 mm-outer diameter and a 1.5 mm-thickness. The quantity of eluted alkali measured for vial P was 0.74 mL.

(6) Separate from the above, the same glass tubes were formed into cup-shaped containers (cup A) by forming a bottom with an automatic vertical forming machine. The quantity of eluted alkali measured for cup A was 0.10 mL. Using a horizontal forming machine, cup A was provided with a mouth to form it into a vial (vial Q) in accordance with the forming process of the present invention (bottom-forming to mouth-forming process). The quantity of eluted alkali measured for vial Q was also 0.10 mL and there was no change in alkali elution caused by the mouth-forming process. It is believed that this results from the fact that the processing temperature of the mouth-forming is lower than that of the bottom-forming and causes low volatilization of the alkali-containing material.

(7) TABLE-US-00001 TABLE 1 outer diameter Eluted height inner diameter alkali Sample thickness (mm) of mouth (mm) (mL) Vial P 30 60 1.5 12.5 0.74 (mouth-forming > bottom-forming) Cup A same as above 27.0 0.10 Vial Q same as above 12.5 0.10 (bottom-forming> mouth-forming)

Example 2

(8) A borosilicate glass tube with a length of 200 mm was closed at one end thereof with a silicone rubber stopper, held vertically, and the filled with a volume of water and autoclaved at 121 C. for 60 minutes. The quantity of eluted alkali per 100 mL was 0.03 mL. This value was regarded as the quantity of eluted alkali for the vial never affected by processing.

(9) Samples (cup B) were formed from the cup A in Example 1 by fire-blasting an internal surface of the cup A about 10 mm above its bottom with an obliquely-directed oxygen-gas flame about 10 cm long, while holding and rotating the cup A. The quantity of eluted alkali measured for cup B was 0.03 mL. It is believed that this results from the fact that the deteriorated region due to processing is removed by the fire-blasting, thereby recovering the original surface of the borosilicate glass tubes. The fire-blasting was done using a point burner with a 1.0 mm bore diameter which is fed by mixed gas of 0.75 L/min town gas (methane) and 2.20 L/min oxygen to generate an about 10 cm long flame.

(10) Then, the cup B was provided with a mouth by a horizontal forming machine to form it into a vial (vial R), of which the quantity of eluted alkali was 0.03 mL. As mentioned in Example 1, It is believed that this results from the fact that the processing temperature of the mouth-forming is lower than that of the bottom-forming, thus making it harder for the alkali-containing material to volatilize.

(11) TABLE-US-00002 TABLE 2 outer diameter bore Eluted height thickness diameter alkali Sample (mm) (mm) (mL) borosilicate glass 30 60 1.5 27.0 0.03 tube Cup A same as above 27.0 0.10 Cup B same as above 27.0 0.03 (fire-blasting treatment) Vial R same as above 12.5 0.03 (Cup B > mouth- forming)

Example 3

(12) Borosilicate glass tubes with a 40.5 mm-outer diameter and a 1.5 mm-thickness were formed into vials with 78.5 mm-height22.0 mm-internal mouth diameter by the conventional process (mouth-forming to bottom-forming). The quantity of eluted alkali measured for the vial was 0.57 mL. Using the automatic vertical forming machine, a glass tube was provided with a bottom to prepare a cup-shaped container (cup C). The quantity of eluted alkali measured for cup C was 0.21 mL. The quantity of eluted alkali measured for cup D prepared by fire-blasting an internal surface of the cup C was 0.03 mL. The quantity of eluted alkali measured for a vial made from the cup D by provision of a mouth with the horizontal forming machine was 0.03 mL.

(13) TABLE-US-00003 TABLE 3 outer diameter bore Eluted height thickness diameter alkali Sample (mm) (mm) (mL) Vial S 40.5 78.5 1.5 22.0 0.57 (mouth-forming> bottom-forming) Cup C same as above 37.5 0.21 Cup D same as above 37.5 0.03 (fire-blasting treatment) Vial T same as above 22.0 0.03 (Cup D >mouth- forming)

(14) Electron microscopic observation on the cup C showed that there is a deteriorated region due to processing, which has a crater-like pattern resulting from alkali-containing volatiles (a photograph of FIG. 1). On the other hand, electron microscopic observation of the cup D, prepared by fire-blasting the deteriorated region due to processing of cup C, showed that the region corresponding to the deteriorated region due to processing has no crater-like pattern (photograph of FIG. 2). This shows that the deteriorated region due to processing was removed by fire-blasting.

Example 4

(15) Borosilicate glass tubes with a 40.5 mm-outer diameter and a 1.5 mm-thickness were formed into vials with 78.5 mm-height22.0 mm-internal mouth diameter by the conventional process (mouth-forming to bottom-forming). The quantity of eluted alkali measured for the resultant vial was 0.57 mL. Using the point burner which generates a gas-oxygen mixed gas flame (about 10 cm long), the resultant vials were subjected to fire blasting so that the flame is blasted to the deteriorated region about 10 mm above the bottom while rotating the vial. The vial subjected to the fire-blasting for 40 seconds showed that the quantity of eluted alkali was reduced to 0.30 mL, while vial subjected to the fire-blasting for 60 seconds showed that the quantity of eluted alkali was reduced to 0.13 mL. The vials after the fire-blasting treatment possess no change in both shape and size. It is to be noted that the fire-blasting time (seconds) which has an effect on decrease of alkali elution can be shortened by preheating of the vials. From these results, it was confirmed that the deteriorated region of the vials caused by the conventional forming process can be substantially removed by fire-blasting.

(16) TABLE-US-00004 TABLE 4 Outer diameter bore Eluted height thickness diameter alkali Sample (mm) (mm) (mL) Vial S 40.5 78.5 1.5 22.0 0.57 (mouth-forming> bottom-forming) Vial T same as above 22.0 0.30 (fire blasting) (40 seconds) Vial U same as above 22.0 0.13 (fire blasting) (60 seconds)