US3055731A

US3055731A - Method and means for preventing reinfection of the sterilized surface of sheet-like packing material

Info

Publication number: US3055731A
Application number: US716387A
Authority: US
Inventors: Loliger Willi
Original assignee: Alpura AG
Current assignee: Alpura AG
Priority date: 1957-02-22
Filing date: 1958-02-20
Publication date: 1962-09-25
Anticipated expiration: 1979-09-25

Description

Sept. 25, 1962 w. LOLIGER 3,055,731

METHOD AND MEANS FOR PREVENTING REINFECTION OF THE STERILIZED SURFACE OF SHEET-LIKE PACKING MATERIAL 2 Sheets-Sheet 1 Filed Feb. 20, 1958 I/ Q/J' O W m A 4n Sept. 25, 1962 w. LOLIGER 3,055,731

METHOD AND MEANS FOR PREVENTING REINFECTION OF THE STERILIZED SURFACE OF SHEET-LIKE PACKING MATERIAL 2 Sheets-Sheet 2 Filed Feb. 20, 1958 all INVENTOR.

VV/ L64. 1652? BY v f/Vf 7054 6)! 1 United htates 3,55,73l Patented Sept. 25, 1%62 Filed Feb. 20, 1953, Ser. No. 716,387 priority, application Switzerland Feb. 22, 1957 6 Claims. (Cl. 21-2) The present invention relates to a method and means for preventing reinfection of the sterilized surface of flexible sheet-like packing material.

The invention is based on the discovery that when making a container for sterile goods from sheet-like packing material it is sufiicient to sterilize the surface only of the material which surface forms the inside of the subsequently made container. This sterilization is obtained by heating the respective surface of the sheet material while the material is moved towards a package or container forming mechanism. However, it is important to avoid reinfection of the sterilized surface by preventing contact of the surface with surfaces which are not sterile or with air containing germs.

It is an object of the present invention to provide a method for preventing reinfection of strip-like sterilized material while it moves from the locality where it was sterilized to means for forming containers from the material. According to the invention a sterile gaseous or vaporous medium is applied to the sterile side of the material while it moves toward a container making mechanism whereby also the lateral edges of the material are covered with sterile material which is spread onto the material and towards the lateral edges thereof.

The sterile gas is preferably applied along the center line of the sterilized surface of the strip-like material; in addition sterile gas may be applied to the strip between the center line and the lateral edges of the strip. It is of advantage to press at least the lateral marginal zones of the strip-like material by means of the applied sterile medium against a continuous surface whereby the surface of the material which is in contact with the continuous surface is the surface of the material which is opposed to the surface of the material which has been sterilized. The sterile medium which is applied between the center and the lateral edges of the strip-like material is preferably directed at an angle of less than 90 onto the previously sterilized surface and in a direction towards the lateral edges of the strip-like material. Another object of the invention is the provision of a device for performing the aforedescribed method. This device includes guide means for the strip-like material moving towards means for making containers from the material and includes a wall which is substantially parallel to the previously sterilized surface of the strip-like material and spaced therefrom, the wall being provided with at least one outlet for directing a gaseous or vaporous sterile fluid against the sterile surface of the strip-like material. The sterile fluid is applied to the sterile surface of the striplike material between the lateral edges of the latter. The material is preferably guided between two substantially parallel spaced stationary walls which extend beyond the lateral edges of the moving material. The wall which faces the side of the strip-like material, which has not been previously sterilized is preferably provided with an uninterrupted surface supporting the moving material.

The novel features which are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodi- Claims ments thereof when read in connection with the accompanying drawing in which:

FIG. 1 is a part diagrammatic, part sectional perspective view of a device according to the invention.

FIG. 2 illustrates a portion of the wall surface forming part of the device shown in FIG. 1 and through which a sterile medium is applied to the sterilized surface of a moving strip-like material.

FIG. 3 is a part sectional perspective view of a modified device according to the invention which simultaneously serves to form a tube from the treated material.

FIG. 4 is a diagrammatic sectional view of an apparatus for forming and filling containers from the tube formed in the apparatus shown in FIG. 3.

Referring more particularly to FIG. 1 of the drawing, numeral 1 designates a flexible strip-like material whose upper surface has been sterilized by the application of heat in an apparatus as illustrated, for example, in my copending application Serial No. 715,657, filed February 17, 1958. The material 1 is transported by means, not shown, in the direction of the arrow 12 through a space 4 between two parallel spaced walls 2 and 3. The upper surface of the material 1 which surface has been previously sterilized faces the wall 2. The latter forms part of a sheet metal 6 which forms a chamber 5. The wall 3 has a plane uninterrupted surface which is parallel to the wall 2 and which forms a stationary rigid continuous support for the material 1. A conduit 7 communicates with the chamber 5 and receives air from a blower 8 which air is sterilized by passing the air through a ceramic filter 9. The wall 2 is provided with a plurality of outlets 10 which are formed by bores 11 in the sheet metal 6. FIG. 2 more clearly illustrates the location of the outlets in the wall 2.

The device shown in FlGURES 1 and 2 operates as follows:

The strip-like material 1 is moved in the direction of the arrow 12 through the space 4 towards a container forming machine. Sterile air is supplied through the conduit 7 into the chamber 5 from which the air is directed onto the previously sterilized surface of the material 1 through the bores ii. The air preferably leaves the bores ii at an average speed of 5 meters per second.

The bores or apertures ill do not all have the same diameter. The bores are arranged on rows which are parallel to the direction of movement of the material 1. The apertures of the row Illa which is opposite to the longitudinal center line of the strip-like material are closer together and have a larger-diameter than the apertures of the other rows of bores. In this way, a relatively great amount of sterile air is applied to the longitudinal center line of the strip-like material. On each side of the row Illa two additional rows of apertures 10b and Ida are provided in the wall 2. The apertures 1% are smaller than the apertures 10:: and are larger than the apertures liic. The distance between the rows 10b and 100 may be made greater than the distance between the rows 10a and 1011. Furthermore, the distance between the apertures of the rows 10b and lllc are greater than the distance between the apertures of the row 10a. The bores forming the apertures 10c are outwardly slanted so that the sterile air is directed at an angle of less than onto the previously sterilized surface of the material 1 and towards the lateral edges of the striplike material. The air is applied to the material 1 inside of the lateral edges for and lb of the strip-like material.

The aforedescribed apparatus produces the following efiect: The sterile air coming from the outlets 10 is applied to the previously sterilized surface of the moving strip-like material and spreads from the localities where the air impinges against the material substantially at a right angle to the longitudinal axis of the strip-like material and leaves the material 1 and the space 4 in the direction of the arrows 13. Therefore, the lateral edges 1a and 1b of the strip-like material are exclusively 1n contact with sterile air which spreads from the center line of the material in opposite directions to the lateral edges of the material. The entire space 4 is filled with sterile air and the air leaving the apparatus in the direction of the arrows 13 prevents entry of germ-laden exterior air into the space 4 and contact thereof with the sterile surface of the material 1. The jets of sterile air emerging through the apparatus press the material 1, particularly the marginal portions of the material which are adjacent to the lateral edges 1a and 112, against the continuous surface 3.

The bottom surface of the material 1 which rests on the surface 3 and the latter are not sterile. However,

since the lateral edges of the material 1 are contacted,

exclusively by sterile air which spreads out from a locality on the sterilized surface of the material germs which may be on the wall 2 or on the surface of the material which has not been previously sterilized cannot reach the sterilized surface. Germs which may come close to the lateral edges 1a and 1b are continuously 'blown away to the outside and cannot reach the sterilized surface of the material 1. This effect is aided by the outwardly inclined arrangement of the bores forming the apertures 100. Though the apparatus is not enclosed a reinfection of the strip-like material passing therethrough is effectively prevented.

A strip-like material whose front side has been sterilized by means not shown enter the device illustrated in FIG. 3 in the direction of the arrow 24. More particularly, the strip-like material 20 enters a space 23 between

parallel walls

21 and 22. The material 20 may consist of paper carrying a layer of a synthetic substance, for

example, polyethylene on the side which has been prcvi-.

ously sterilized. The sterilized surface of the material 20 faces the wall 21 which is provided with a plurality of outlets 25 through which sterile air can be blown onto the sterilized surface of the material 20. Sterile air is supplied by means of a conduit 26 to a chamber 27 formed between the wall 21 and a wall 28. The wall 22 is formed by sheet metal 19. The

walls

21 and 22 are so bent as to gradually assume a cylindrical configuration in the direction of the arrow 24 so that the material 20 which is moved between the

walls

21 and 22 assumes the configuration of a tube 20'. The lower portion of the wall 21 forms a complete cylinder whereas the lateral edges of the wall 22 remain spaced, forming a slot 29. The lower end of the Wall 21 extends below the lower end of the wall 22 and forms a tube 21. The

walls

21 and 22 are spaced by means of spacers 31. The lower end of the wall 22 is connected with the casing 31 of a container forming and filling machine.

Due to the superposition of the longitudinal marginal portions of the strip-like material 20 at the lower end of the apparatus shown in FIG. 3 a tube 20' is formed. Because of the application of sterile air to the previously sterilized surface of the material 20 a reinfection of this sterilized surface, while the material is moved to and through the tube forming apparatus, is prevented.

A pressure roller 30 rotatably supported on the wall 21 by means of holders 18 engages the inside of the tube 20'. A heating shoe 33 connected with the casing 31 by means of supports 32 is pressed against the part of the overlapping marginal portions of the material 20 which are engaged by the roller 30. The shoe 33 is electrically heated and effects cohesion of the marginal portions of the material 20 by heating the synthetic substance layer. The material to be filled into the subsequently formed containers is supplied into the tube 20' by means of a filling tube 34. The tube 20' is compressed by electrically

heated shoes

35 and 36 which are individually mounted on links of

endless chains

37 and 38, respectively. The chains run on

sprocket wheels

39, 40

and 41, 42, respectively, the wheels 39 and 41 being rotated by drive means, not shown. There is an additional pair of heated press shoes which are not shown and which are placed at a right angle to the illustrated

shoes

35 and 36. These additional shoes are also mounted on chains and the movement of the additional chains is so synchronized with that of the illustrated chains that the tube 20 is alternately squeezed at predetermined intervals in directions which are at a right angle with respect to each other. The movement of the press shoes causes a downward movement of the material 20 and of the tube 20'. Before the tube 20' reache the press shoes 35, 36 it is filled approximately up to the level 17 by material supplied through the tube 34. The action of the

heated press shoes

35, 36 and the shoes not shown transforms the tube 20' to a chain of containers 43.

When starting the apparatus shown in FIGURES 3/ and 4 the strip-like material 20 one surface of which has already been sterilized is transformed into the tube 20' before the material filling the subsequently produced containers is supplied. The lower end of the newly formed tube 20, is compressed and sealed by the

heated shoes

35 and 36 so that the bottom of the tube is closed. While the filling and container forming machine stands still a heating agent, for example, superheated steam of 350 C. is conducted through the pipe 26 into the chamber 27 so that this chamber and the wall 21 are heated to sterilization temperature. At the same time superheated steam is blown through the filling tube 34 into the already formed tube 20'. The steam escapes in an upward direction, heating the roller 30 and the holders 18 as well as the outside of the filling tube 34 to sterilization temperature. Thereupon supply of superheated steam is stopped and sterile air is supplied through the pipe 26 into the chamber 27 and blown through the apertures 25 onto the sterilized surface of the material 20 which subsequently forms the inside of the tube 20'. The filling and container forming machine can now again be started. The substance to be filled, for example, milk is continuously supplied through the conduit 34 into the continuously forming tube 20'. The previously sterilized surface of the material 20 does not come in contact with germ-laden air or with surfaces which are not sterilized during the aforedescribed operation so that there are no germs within the subsequently formed and closed containers.

If the packing material cannot withstand the temperatures which are produced by the supply of superheated steam during starting of the apparatus, aluminum foil may be glued to the first part of the strip-like material 20 entering the apparatus so that the beginning of the tube 20 is formed of aluminum foil.

The invention is not limited to the aforedescribed embodiments. The apertures through which the sterile medium is applied to the previously sterilized surface may, for example, be in the form of slots. Instead of sterilized air another sterile medium, for example, nitrogen may be used.

I claim:

1. A method for preventing reinfection of the sterile side only of a flexible strip-like material which side has been previously sterilized, the material moving in longitudinal direction towards an apparatus for forming containers of the strip-like material whereby the sterile side is on the inside of the containers, the method including the steps of applying to and maintaining a continuous film of a sterile gas on the sterile side only, and spreading the sterile gas onto the sterile side to flow on said side from the center of the material towards the lateral edges of the strip-like material while maintaining a thin uninterrupted layer of sterile gas adjacent to said side.

2. The method defined in claim 1 wherein the major portion of the sterile gas is applied to the material along the longitudinal center line of the sterile side only of the material.

3. The method according to claim 2 wherein additional sterile gas is applied to localities of the sterile side only of the material which localities are between the longitudinal center line and the lateral edges of the strip-like material.

4. The method according to claim 3 wherein the additional sterile gas is directed at an angle of less than 90 onto the sterile side only and in a direction towards the lateral edges of the strip-like material.

5. A method for preventing reinfection of the sterile side only of a flexible strip-like material moving in longitudinal direction towards an apparatus for forming containers of the strip-like material whereby the sterile side is on the inside of the containers, the method including the steps of applying to and maintaining a thin uninterrupted layer of a sterile gas on the sterile side only, spreading the sterile gas onto the sterile side to flow on said side towards the lateral edges of the strip-like material, and pressing, by the pressure of the applied gas, at least the lateral marginal portions of the side of the material which side is opposite the sterile side onto a continuous, rigid surface.

6. An apparatus for preventing reinfection of the sterile side only of a flexible strip-like impervious material moving continuously towards means for making containers from the material with the sterile side forming the interior of the containers, the apparatus comprising stationary guide means having closely spaced opposed parallel guide surfaces between which the material moves in parallel relation, said spaced guide surfaces being individually directly opposite the sides of the material, the guide surface which is directly opposite the sterile side of the material being provided with means for continuously discharging a sterile gas directly onto the sterile side only of the moving material between the lateral edges of the material, the guide surface which is opposite the sterile side of the material being spaced from the material for causing the sterile gas to form an uninterrupted film adjacent to the sterile side of the material.

References Cited in the file of this patent UNITED STATES PATENTS 1,219,130 Monvoisin Mar. 13, 1917 1,881,310 Coatsworth Oct. 4, 1932 1,885,142 Reece et al Nov. 1, 1932 2,321,152 Mengle June 8, 1943 FOREIGN PATENTS 325,052 Great Britain Feb. 13, 1930

Claims

1. A METHOD FOR PREVENTING REINFECTION OF THE STERILE SIDE ONLY OF A FLEXIBLE STRIP-LIKE MATERIAL WHICH SIDE HAS BEEN PREVIOUSLY STERILIZED, THE MATERIAL MOVING IN LONGITUDINAL DIRECTION TOWARDS AN APPARATUS FOR FORMING CONTAINERS OF THE STRIP-LIKE MATERIAL WHEREBY THE STERILE SIDE IS ON THE INSIDE OF THE CONTAINERS, THE METHOD INCLUDING THE STEPS OF APPLYING TO AND MAINTAINING A CONTINUOUS FIRM OF A STERILE GAS ON THE STERILE SIDE ONLY, AND SPEADING THE STERILE GAS ONTO THE STERILE SIDE TO FLOW ON SAID SIDE FROM THE CENTER OF THE MATERIAL TOWARDS THE LATERAL EDGES OF THE STRIP-LIKE MATERIAL WHILE MAINTAINING A THIN UNINTERRUPTED LAYER OF STERILE GAS ADJACENT TO SAID SIDE.