US 2429482 A
Description (OCR text may contain errors)
Oct. 21, 1947. c. s. MUNTERS METHOD AND MEANS FOR THE PRODUCTION OF FOIL MATERIAL Filed Jan. 5, 1943 2 Sheets-Sheet 1 Fig.1
HYYENTV'R A W Wv METHOD AND MEANS FOR THE PRODUCTION OF FOIL MATERIAL Q M *w Patented Oct. 21, 1947 METHOD AND MEANS FOR THE PRODUC- TION OF FOIL MATERIAL Carl Georg Munters, Stocksund, Sweden Application January 5, 1943, Serial No. 471,345
In Sweden April 6, 1939 6 Claims. 1
My invention relates to sheet material for instance such as is used for packages. Furthermore, the invention relates to sheets which consist of an artificial mass which softens when heated and which preferably is transparent. The sheets are provided with corrugations, bulges or the like, and two or more sheets may be united with each other at the tops of these corrugations or bulges in a manner such that a composite board or wall is obtained which is comparatively 2 I of steam which is conducted in a known manner through the interior of the rollers. It is preferable to preheat the film 28, prior to its entrance between the rollers 28, 29, to a temperature corresponding, approximately at least, to the temperature of these rollers. Such preheating may rigid or resistive against bending in one direction at least.
To provide such corrugations, the sheets may be folded in the cold state in a suitable machine so as to produce more or less sharp edges. However, this method is not suitable, particularly for packages composed of transparent sheets, for the reason that the sheets are apt to break on account oftheir relative brittleness, which impairs their strength and appearance in the finished packaging material. Moreover, the corrugations are not of uniform shape when made in this way which, inter alia, also impair the strength of the package. In addition, this method is limited to constructions with sharp rectilinear pleats over the surface of the sheet, and consequently, for instance, it is not possible to impart a softly rounded shape to the pleats.
It is the object of the invention to overcome these difficulties and to attain a continuous and economic production of the sheet material.
Further objects and advantages of the invention will be apparent from the following description considered in connection with the accompanying drawings which form a part of this specification, and of which:
Fig. 1 shows a machine more or less diagrammatically and partly in section, for the production of sheets according to the invention.
Fig. 2 shows a modified machine partly in section in accordance with the invention.
Fig. 3 is a sectional view on the line IH-III of Fig. 2.
In Fig. l, 25 denotes a rotatably mounted roller having a roll of transparent material, such as acetyl cellulose, wound thereon. From this roll, the film 26 is conveyed, if desired over a guide roller 21, in between two rollers 28, 29, the ex-- ternal surfaces of which are formed with a profile corresponding to the desired shape of the films. In the present case, the rollers are provided with axially extending tooth-like projections engaging one another, as will be seen from the figure. The rollers 28, 29 are heated to a suitable temperature, for instance with the aidbe effected with the aid of one or more preheating rollers, or by means of hot air, and the web may be heat-insulated, as at 50. The film 28 is corrugated during its passage through the teeth meshing with each other. By reason of the heatingprocedure the film has become soft and plastic. The film remains in the teeth of the roller 29 during its continued rotation and passes between this roller and another roller 30, provided with teeth in mesh with the teeth of the roller 29. Devices known per se are preferably made use of to loosen the film from the roller-28 and to keep the same in the teeth of the roller 28. The roller 30 need not press against the roller 29, a certain play being preferably provided between the teeth thereof. Preferably, the roller 30 is driven by means of a synchronizing gear, so that contact between the roller teeth and iamming of the film will not occur. The film can thus conveniently move laterally under the change in temperature occurring by the fact that the roller 30 is comparatively cold or cooled and of such a temperature that the film becomes set and rigid so as to retain the corrugated shape thereof.
Arranged beside the roller 30 is a device for applying adhesive or solvent, such as acetone, on the ridges of the corrugated film. In Fig. 1, this device is representated diagrammatically bya receptacle 3|, containing the adhesive or solvent, and a rotatable roller or the like 32, which dips down into the receptacle H with the lower portion thereof and makes contact with the film car ried by the roller 30. If desired, the roller 32 may be adapted to be thrown out of engagement automatically, when the machine is stopped, to prevent the film from being dissolved by the acetone and from sticking to the roller 30.
. A rotatably mounted roller 33 carries another roll of film, preferably of the same transparent material as the film 26. From this roll, a web 34 is conveyed over a roller 35 having a cylindrical external surface, said latter roller being pressed against the roller 30 for instance by means of springs or the like. The corrugated film 26 and the plane film 34 are secured to each other during their passage between the rollers 30 and 85.
The two united films may now be removed transparent material as that of the films 26,-
from which a web 40 is conveyed over the roller 38. By means of a device 3|, 32 of the type above described, the free ridges of the corrugated film 36 are moistened with solvent or adhesive substance such as acetone, the web 40 being secured to these ridges between the rollers 31, 38. An enless belt 42 may be provided between the roller 31 and a roller 4|. In the same manner, a belt 43 extends between the roller 38 and a roller 44. The portions of the belts 42, 43 facing one another may be adapted to cooperate with supporting rollers 45 to keep the belts properly spaced from one another so as to cause the belts to press on the sheet. During the passage of the sheet between the belts 42, 43 the attaching of the films to each other is ensured. The sheet is dried between the belts, if desired with the aid of a fan producing an air current between the films. For the same purpose, the sheet may be heated during its passage between the belts 42, 43, for instance by means of hot air.
Those portions of the webs where the solvent is applied, may be surrounded by casings 5i and 46, respectively, to prevent said substance from escaping freely into the surrounding atmosphere. A suction pump 41 may communicate with the casing 46 through a conduit 48. The pump 41 sucks out the air containing the solvent, to a receptacle 49 containing a suitable absorbing agent, such as silica gel.
The preheating of the film 26 prior to its entering between the rollers 28, 29 is of importance to bring about a uniform and smooth surface, it being found that the material according to the invention most frequently has, as compared with paper, for example, a very great coefficient of heat expansion, which results in creasing or buckling of the films if they are warmed while being jammed between the rollers when being corrugated. During th heating proper, the film thus is permitted to expand freely. In order also to avoid tensions in the films, during the interconnection of the same, by reason of the high coefficient of expansion of the material, it is of great importance that the two films 26, 34 have substantially the same temperature. On the other hand, should'the films have different temperatures, the cooling of the warm film will cause a contraction of the same, which results in creasing or buckling of the cold film. Many advantages are gained by the fact that the rollers 30 and 35, respectively, and the films are relatively cold. Thus solvents, such as acetone, having a boiling point lower than the temperature required for the deformation of the films, may be used to advantage, without the substance in consideration boiling off. By reason of the fact that the rollers 30, 35 and the films bearing thereon are cold or at room temperature, it will be possible even to unite films of materials of different coefllcients of expansion Without disadvantage. If the solvent causes a temporary expansion of the one film, the temperature of the other may be chosen higher in a manner such that, after the solvent has evaporated and both films are cooled down to room temperature tensions in the films, that may cause creases and the like, are eliminated. A further important property according to the invention is, as will appear from the above, that the temperature be selected so that the occurrence of unfavorable tensions in the finished product is avoided as far as possible.
With respect to the appearance of the films, it is of importance that the acetone or the solvent or adhesive substance be applied to th tops of th corrugations.
In the apparatus above described, the attaching of the transparent films to each other takes place continuously. After the sheet composed of three films has passed between the belts 42 and 43, it may be cut, for instance, into suitable lengths. The invention also includes a construction, wherein the finished sheet only consists of one plane and one corrugated film, as indicated at 36. A sheet composed in this manner may be wound onto rollers without difiiculty.
Furthermore, it is obviously conceivable to secure more than three films to each other, for instance in such a manner that alternate films are plane and intermediate ones are corrugated. As a material for the films, so-called secondary acetyl cellulose will be found particularly suitable, permitting of being shaped at 90-130 degrees Centigrade. In place of acetone or methyl ketone, which boils at 56 to 58 degrees centigrade, methyl-ethylen ketone may be employed. As a further exampl of solvents may be mentioned methyl glycol acetate with a boiling point of 138-152 degrees centigrade, which is particularly serviceable when pasting is effected in a warm state. So-called primary acetyl cellulose may also be used in certain cases. Examples of such acetyl cellulose are viscos and Cellophane.
In certain cases, it may be suitable, for instance in order to permit a lateral expansion of the film, to arrange the rollers 28 and 29 relatively to each othe in a manner similar. to the arrangement of the rollers 29, 30, as described hereinbefore.
In Figs. 2 and 3, H0 is the frame of the machine, which carries a roller III provided with an outer profile II2 corresponding to the desired shape of the foils. In the present case, the roller III is formed with axially extending teeth. The roller III is rotatably mounted in bearings III rigidly connected with the frame llll. Fitted into an internal bore in the roller with a small clearance therein is a stationary shaft II4 which is rigidly connected to the frame. The cylindrical external surface of the stationary shaft H4 is cutaway over a portion of the periphery of the surface to form a recess I I5 having an axial length corresponding to the length of the teeth I I2. The recess II5 communicates through a passage II. and a pipe I II with a vacuum pump (not shown). A recess H8 is arranged adjacent to said recess H5 while being separated therefrom, and may either communicate with the atmosphere or be supplied with air under pressure from a source of pressure through an axial channel 9 in the shaft H4 and a conduit I20. Furthermore, the shaft I I4 has an inner recessi 2 I, which is adapted to be traversedby a heating medium, such as steam, oil or the like, which is introduced through a passage I22 and a pipe I23 extending over the major portion of the length of the recess Hi. The steam escapes through a channel I24, which is located in the same end of the shaft as the passage I22. The roller I I I is provided with radial passages I25 extending therethrough, said passages opening at the bottom of the teeth II2. As
will appear from the figures, these passages may be arranged in staggered relation to each other.
and in which is provided a stationary shaft I2i with a small clearance. The shaft I21" is provided with an internal recess I28, to which is supplied a heating medium through a pipe I29 similar to the pipe I23. Furthermore, the shaft I21 is preferably formed with an outer recess I30 which may communicate with the atmosphere, or which may have air under pressure supplied thereto. The outer peripheral portion ofthe roller I26 carries teeth adapted to engage the teeth H2 of the roller III. Radial passages I25 extend from the inside of the roller to the bottom of the teeth thereof.
A third roller I3I is formed with teeth engaging the teeth of the roller III. The roller I3I is provided with an inner bore having a stationary shaft I32 fitted into the same. The shaft I32 is provided with a recess I33 extending from the surface thereof, sald recess communicating with a vacuum source through a passage I3I. Furthermore, the roller I3I is provided with an inner recess I35 traversed by a cooling agent, such as water, which may be introduced through a pipe conduit I36 of the same shape as that of the conduit I23.. Immediately adjacent to' the recess I83 but separated therefrom, there is provided a groove or channel I 37 in the surface of the shaft I32, said. groove or channel communicating with the atmosphere or with a source of compressed air. The roller I3I is provided, similar to the other rollers, with radially extending passages I25.
Bearing on the roller I3I is a roller I38 having a smooth cylindrical outer surface. If desired, special means may be provided to bring about or to control a suitable pressure between the rollers WI and I38. In Fig. 2, I39 designates a receptacle for a solvent such as acetone. Dipping into this solvent is a roller Iifl or the like, while another roller III bears on said roller as well as on the ridges of the foil web engaging the roller I3I. The rollers Md and IIII are rotatable, so that solvent will be conveyed by means of the same to the ridges or undulation crests of the foils. If
desired, the rollers Hit and MI may be enclosed -within a casing I52.
The recess H5 in the shaft II extends in a peripheral direction between or substantially between the points of engagement of the roller III with the rollers I23 and I3I. The partition separating the recesses II5 and H8 is located right opposite the point of tooth engagement between the rollers II I and ISI or somewhat in advance of said point. The recess I33 inthc shaft I32 extends between the points of engagement or contact between the roller I3I and the rollers I I I and I33.
A web N3 of acetyl cellulose, for example, is conveyed from a roll through a space bounded by walls I48 adapted to supply heat to the web so as to preheat the same. The web may slide on the one wall of the space so as to increase the heat transmission. The web then passes between two rollers Ills provided with heating devices, the latter rollers also ensuring that the web is maintained altogether uniform and smooth. After that the web is led in between the teeth of the rollers III and I26 so as to be corrugated thereby. The webis then maintained in the teeth of the roller III, which is ensured according to the invention by the fact that the surface of the web facing the roller is held by suction to these teeth by means oi the partial vacuum existing within recess H5 and communicated through the passages I25 to the web. To facilitate the removal of the web from the engagement with the teeth of the roller I28. air under pressure may be-introduced through the recess I30, said air causing a pressure on the web through the passages I25 in a direction from the roller I28. When the web reaches the point of engagement between the rollers III and I 3|, the communication is interrupted between the corresponding passages I25 and the recess -I I5. At the same time, the pressure below atmospheric retaining the web to the roller II I ceases. The web is instead subjected to a sucking effect from the passages I25 in the roller I3I communicating with the recess I33 of the shaft I32, which results in release of the web from its engagement with the teeth of the roller III, and is transferred onto the teeth of the roller I3I. In the embodiment according to Figs. 2 and 3, the compressed air escaping through the passages I25 located opposite the recess IIB facilitates the release of the'web from the teeth of the roller III,
and at the same time presses it against the teeth of the roller I3I. To increase this pressing effect, a plate I 45 may be provided, if desired, between and over the sides of the rollers III and I3I, so that the compressed air escaping from the recess H8 is urged against the weblying on the roller I3I. If desired, the plate I45 may be provided with one or more apertures connected to a source of compressed air.
The web is cooled down by the roller -I3l and will maintain its form. The rollers I40, III moisten the .undulation crests with" solvent. Therefore, when a second web I46 is introduced between the smooth roller I38 and the roller I3I, the two webs will be pasted together so that a composite sheet is obtained, as indicated at 61 in Fig. 2.
While several embodiments of the invention have been shown, it is to be understood that these are for purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.
What I claim is:
l. The method of continuously forming a foil of thermoplasticmaterial having a multiplicity of projections and depressions which includes feeding a sheet of such foil through a heating zone to soften it while permitting thermal expansion of the heated material, forming the desired projections and depressions in the softened foil by applying pressure to the opposite sides of the foil, carrying the formed foil in its softened state from the forming station on a heated supporting surface to prevent deformation of the foil, stripping the foil from said heated surface and transferring it to a chilling surface providing support for and permitting relatively free contraction of the formed foil, and carrying the foil on said chilling surface to cool and set the foil in its formed state.
2. The method of continuously forming thermoplastic material comprising a foil having a multiplicity of projections and depressions and having a backing sheet which includes feeding a sheet of such foil through a. heating zone to soften it while permitting thermal expansion of the heated material, forming the desired projections and depressions in the softened foil by applying pressureto the opposite sides of the foil,
carrying the formed foil in its softened state from the forming station on a heated supporting surface '0 prevent deformation of the foil, stripping t e foil from said heated surface and transferring it to a chilling surface providing support for and permitting relatively free contraction of the formed foil, carrying the foil on said chilling surface to cool and set the foil in its formed state, and attaching to:the crests of the projections n the formed foil a backing sheet of thermoplastic material at approximately the same temperature as that of the formed foil.
3. The method of continuously forming thermoplastic material having a multiplicity of projections and depressions and a backing sheet which includes feeding a sheet of such foil through a heating zone to soften it while permitting thermal expansion of the heated material, forming the desired projections and depressions in the softened foil by applying pressure to the opposite sides of the foil, carrying the formed foil in its softened state from the forming station on a heated supporting surface to prevent deformation of the foil, stripping the foil from said heated surface and transferring it to a chilling surface providing support for and permitting relatively free contraction of the formed foil, carrying the foil on said chilling surface to cool and set the foil in its formed state, applying a solvent to the crests of the projections of the foil and pressing a backing sheet of thermoplastic material at approximately the same temperature as that of the foil to the solvent treated crests.
4. The method of continuously forming a foil of thermoplastic material having a multiplicity of projections and depressions which includes feeding a sheet of such foil through a heating zone to soften it while permitting thermal expansion of the heated material, maintaining the film hot up to the time it comes in contact with the first forming roller, forming the desired projections and depressions in the softened foil by applying pressure to the opposite sides of the foil, carrying the formed foil in its softened state from the forming station on a heated supporting surface to prevent deformation of the foil, stripping the foil from said heated surface and transferring it to a chilling surface providing support for and permitting relatively free contraction of the formed foil, and carrying the foil on said chilling surface to cool and set the foil in its formed state. 7
5. In apparatus of the character described, a heating de'ice for softening a moving foil of thermoplastic material while providing for thermal expansion of the foil, a first and a second forming roller provided with intermeshing projections and depressions, means for heating said rollers, means for passing the softened foil between said rollers to form it, means for maintaining the film hot between said heating means and where it passes between said heated rollers, means for stripping the formed foil from the first roller and carrying it in its softened state on the surface of said second roller away from the forming station, a chilling roller having projections and depressions meshing with said second roller and engaging said foil at a place spaced from said forming station to effect a preliminary setting of the softened foil while it is supported by said second roller and means for stripping the foil from said second roller and carrying it in its formed state on the surface of said chilling roller to further cool and set the foil.
6. In apparatus of the character described a heating device for softening a moving foil of thermoplastic material while providing for thermal expansion of the foil, first and second forming rollers provided with intermeshing projections and depressions, passageways between said depressions and the interior of said rolls, means for introducing air under pressure into the passageways in said first roll to strip the formed foil therefrom, means to introduce a vacuum in the passageways of said second roll over a portion of the circumference thereof to hold the foil on said second roll, means associated with said second roll to introduce air under pressure into said passageways to strip the foil therefrom at a predetermined position in the rotation thereof, a chilling roller having projections and depressions meshing with said second roller and engaging said foil to effect a preliminary setting of the softened foil while it is supported by said second roller, passageways formed in said second roller between said depressions and the interior thereof, means for introducing a vacuum into said passageway in said chilling roll to retain the foil thereon during a portion of one rotation thereof and means for introducing air under pressure into said passageways at a predetermined rate in the rotation of said chilling roller to strip the foil therefrom.
CARL GEORG MUNTERS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,981,338 Swift, J1 NOV. 20, 1934 657,100 Ferres Sept. 4, 1900 1,146,771 Raflel July 13, 1915 1,473,096 H111 et al. NOV. 6, 1923 1,264,506 Hahn Apr. 30, 1918 2,018,240 Swift, Jr. Oct. 22, 1935 1,595,346 Long et al A118. 10, 1926