Patent Application
20060239866
The present invention relates to glass safety tube that contains an encapsulating protective barrier that contains the glass tube and its contents if the glass tube is fractured or broken.
Traditionally, test tubes and vacuum tubes have been made from glass. However, in recent years, due to the inherent danger of handling infectious fluids in a glass container, plastic test tubes and vacuum tubes have become more popular. While plastic tubes may be safer than glass tubes for handling infectious fluids, many medical professionals still prefer glass tubes for several reasons. For example, plastic vacuum tubes have a tendency to prematurely loose their vacuum. Therefore, it would be desirable to provide a glass tube that is safer for handling fluids of all types.
In order to make glass test tubes and vacuum tubes safer, it has been suggested to wrap the external surface of the glass tube with protective sheeting. However, most inexpensive polymer sheeting lack sufficient strength to encapsulate the glass tube when it fractures or breaks. Further, polymer sheeting does not lay neatly on the closed, bulbous end of the glass tube.
To protect the bulbous, closed end of the tube, it has been suggested to apply a form-fitted, plastic cap. However, a plastic cap is cost prohibitive compared to the cost of mass manufactured glass test tubes or vacuum tubes. Further, since the tolerance is high for such mass produced test tubes and vacuum tubes, a standard plastic cap would likely fail to properly engage a large percentage of such glass tubes. Therefore, it would be desirable to provide a glass safety tube that can be mass produced at a cost comparable to an unprotected glass test tube or vacuum tube.
The present invention provides a glass safety tube having an encapsulating protective safety barrier that contains the glass tube and its contents in the event the glass tube is fractured or broken. The safety tube can be mass produced without substantially adding to its cost compared to an unprotected glass test tube or vacuum tube.
The glass tube has an overall length L1, and an elongate tubular central portion with a diameter D and a length L2, which is less than L1. The glass tube has an open end, and a bulbous closed end portion integrally formed with the central portion and axially extending a distance L3 from the central portion. The open end of the glass tube may have an integrally-formed, radially-projecting lip.
A first safety barrier envelops the central portion of the glass tube. The first safety barrier comprises transparent, tear-resistant, polymer sheeting adhered to and wrapped around the central portion. Preferably, the sheeting comprises a heat sealable polyester film that is adhered to the central portion. In the preferred embodiment, the sheeting comprises oven-lidding Mylar®. Preferably, the sheeting does not envelop the lip at the open end of the glass tube.
In a preferred embodiment, one end of the sheeting extends axially past the interface of the central portion and the closed end portion of the glass tube 12. The extension portion does not contact the closed end portion of the glass tube. Rather, the extension portion forms an annular reservoir surrounding the closed end portion.
A second safety barrier envelops the closed end portion of the glass tube. The second safety barrier comprises an adhesive that adheres to the closed end portion of the glass tube and to the extension portion of the sheeting. Preferably, the second safety barrier may comprise a hot melt adhesive, a quick-cure epoxy, or a UV cured adhesive. The adhesive forms a flush interface with the ends of the extension portion.
Other embodiments of glass safety tube are provided. In some alternative embodiments, protection of the closed end portion of the glass tube is reduced or eliminated to reduce the cost of the safety tube.
The present invention also provides a method of making the glass safety tube. In accordance with the method, the glass tube is initially heated. The central portion of the glass tube is then wrapped with the tear-resistant, polymer sheeting. The annular reservoir is formed around the closed end portion by axially extending the sheeting past the interface of the central portion and the closed end portion without contacting the closed end portion.
After the glass tube is wrapped, the glass tube is oriented vertically with the closed end oriented upwardly. The closed end is then enveloped by depositing a fluid adhesive on the closed end, and then allowing the adhesive to cure. The adhesive is contained within the reservoir and prevented from contacting the central portion of the tube. The adhesive forms a flush interface with the end of the sheeting.
For the purpose of illustration, there is shown in the accompanying drawings several embodiments of the invention. However, it should be understood by those of ordinary skill in the art that the invention is not limited to the precise arrangements and instrumentalities shown therein and described below. To more clearly illustrate the invention, the drawings are not to scale.
A glass safety tube in accordance with an embodiment of the invention is shown in
The glass safety tube 10 comprises a glass test tube, designated generally by reference numeral 12, having an open end 14, an elongate, tubular central portion 18, and a generally-bulbous, closed end portion 20 integrally formed with the central portion 18. The open end 14 may also include an integrally-formed, radially-projecting lip 16, which is formed by fire polishing. Referring to
A first safety barrier envelops the central portion 18 of the glass tube 12. In the embodiment shown in
For best results, the sheeting 22 comprises 1.5 mil, oven-lidding Mylar® sold by Dupont Teijin Films. The Mylar® sheeting has an inner adhesive layer and is typically supplied as a non-tacky film sheet with no peelable backing layer. The adhesive becomes tacky at about 200° F. and has excellent adhesive properties.
Referring to
In the preferred embodiment, the sheeting 22 is adhered to the glass tube 12 by an adhesive that is provided as a layer on the sheeting 22. However, it is within the scope of the present invention to adhere non-adhesive sheeting to the glass tube by first applying a separate adhesive and then applying the non-adhesive sheeting.
The sheeting 22 is preferably clear so that the user can observe the contents of the glass tube 12. If the sheeting 22 is wrinkled or otherwise not laid flay over itself, clarity will be obstructed. To prevent wrinkling, the sheeting preferably does not overlay the radial lip. Instead, the first axial end 24 of the sheeting 22 is applied immediately adjacent the radial lip 16 of the glass tube 12 as best seen in
Referring to
As best seen in
A second safety barrier adheres to and envelops the closed end portion 20 of the glass tube 12. In the embodiment shown in
Referring to
In a preferred embodiment shown in
In the embodiment shown in
The sheeting 22 and adhesive 28 generally increase the strength of the glass tube 12 to prevent breakage. Further, the sheeting 22 and adhesive 28 form a very durable encapsulating safety barrier than contains the glass tube and its contents if the glass tube is fractured or broken. Under normal circumstances, the safety barrier remains intact and protects the user from injury or contamination if the glass tube is fractured or broken.
In a preferred embodiment, the safety tube 10 is made by initially providing a glass tube 12 as described above. The glass tube 12 is heated to about 200-275° F. The central portion 18 of the tube is then wrapped with the tear-resistant polymer sheeting 22. The second axial end 26 of the sheeting 22 is extended past the interface P of the central portion 18 and the closed end portion 20, thereby forming an annular reservoir surrounding the closed end portion 20. During wrapping, the glass tube 12 may be oriented vertically or horizontally.
After the glass tube 12 is wrapped, it is oriented vertically with the closed end portion 20 oriented upwardly. The second safety barrier is then formed by depositing a predetermined amount of adhesive 28 on the closed end portion 20 of the glass tube and allowing the adhesive 28 to cure. If hot melt glue is selected as the second safety barrier, the glue should be applied in a circular pattern around the periphery of the reservoir to prevent formation of air pockets in the deepest channels of the reservoir. If epoxy or UV cured adhesives are selected as the second safety barrier, the adhesive may be centrally deposited at the apex of the closed end portion 20. Depending on the adhesive, the curing process may be accelerated by heating.
In a preferred embodiment, the length of the extension portion 30 of the sheeting 22 is less than or about equal to the length L3 of the closed end portion 20. In this embodiment, the amount of adhesive 28 deposited on the glass tube 12 is controlled so that the adhesive does not overflow the reservoir but forms a flush interface with the first axial end 24 of the sheeting 22.
A glass safety tube in accordance with a further embodiment of the invention is shown in
A glass safety tube in accordance with an additional embodiment of the invention is shown in
A glass safety tube in accordance with yet another embodiment of the invention is shown in
A glass safety tube in accordance with yet another embodiment of the invention is shown in
The safety tube 410 has a construction similar to the safety tube 10 described above. However, in this less expensive embodiment, no second barrier layer is provided on the closed end portion 420 of the glass tube 412 because it is generally the strongest portion of the glass tube 412. Instead, the extension portion 430 of the sheeting 422 extends axially a distance greater than L3 and provides impact protection to the closed end portion 420. The extension portion 430 is elastically deformable and acts like shock absorber in the event the safety tube 410 is dropped or otherwise impacted on the closed end 430. However, the extension portion 430 does not encapsulate the closed end portion 430 if it is fractured or broken. While the closed end portion 420 has no encapsulation or impact protection, the safety tube 410 it is cheaper to manufacture than the embodiment shown in
A glass safety tube in accordance with yet another embodiment of the invention is shown in
The safety tube 510 has a construction similar to the safety tube 10 described above. However, in this embodiment, no second barrier layer is provided on the closed end portion 420 of the glass tube 412 because it is generally the strongest portion of the glass tube 412. Further, the protective sheeting 522 extends only from immediately adjacent the radial lip 516 to the axial interface P of the central portion 518 and the closed end portion 520 of the glass tube 512. While the closed end portion 520 has no encapsulation or impact protection, the safety tube 510 is cheaper to manufacture than the embodiment shown in
The embodiments shown in
While the principles of the invention have been described above in connection with specific embodiments, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.
