GB805733A - Process of transverse stretching of films of thermoplastic material - Google Patents
Process of transverse stretching of films of thermoplastic materialInfo
- Publication number
- GB805733A GB805733A GB10363/55A GB1036355A GB805733A GB 805733 A GB805733 A GB 805733A GB 10363/55 A GB10363/55 A GB 10363/55A GB 1036355 A GB1036355 A GB 1036355A GB 805733 A GB805733 A GB 805733A
- Authority
- GB
- United Kingdom
- Prior art keywords
- film
- liquid
- clamps
- stretching
- tank
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
- B29C55/08—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique transverse to the direction of feed
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
Abstract
In a continuous process for transversely stretching a travelling continuous film of a thermoplastic synthetic organic polymeric material, the advancing film, during a transverse stretching operation, is treated on one side only by direct contact with a hot vapour or a hot liquid. The treating agent may be steam, hot water or a hot organic liquid containing water, such as hot aqueous ethyl alcohol. As shown in Figs. 1 and 3, a continuous film 1 is led in a taut condition over the open top of a tank 2 which gradually widens in the direction of travel of the film and is provided with a horizontal rim 3. The tank is filled with a hot treating liquid 4 to a level which, when the liquid is still, is slightly below the brim. Two series of clamps 5, which hold the edges of the film, are attached to the chains of a stretching frame and are conveyed along the rim 3 of the tank 2 and follow its widening, thereby transversely stretching the film. The film is in con <PICT:0805733/IV (a)/1> <PICT:0805733/IV (a)/2> <PICT:0805733/IV (a)/3> tact with the rim 3, so that it seals the mouth of the tank and the lateral edges of the film are kept out of contact with the treating liquid. During this stretching operation the hot treating liquid is made to wash up against the underside of the film by pumping the liquid under pressure through pipes 6 (Figs. 2 and 3) immersed in the liquid and provided at their upper sides with openings 7. A stream of liquid is thus ejected through each opening 7 through the main body of the liquid, as shown by the arrows in Fig. 3, and impinges on to the underside of the film, leaving air pockets 12 in the main body of the liquid. An analogous method is used when the underside of the film is treated with a hot vapour. The tank 2 is provided with overflow ducts which conduct the treating liquid to an external heater which re-adjusts it to the desired temperature and from which it is returned to the tank by means of a circulating pump via the pipes 6. Advantageously the film is first led, while already clamped to the chains of the stretching device, but without being stretched, through the zone 8 (Fig. 1) of the stretching frame in which the chains travel parallel to one another before entering section 9 of the stretching frame, where the clamp chains diverge. The film is thus heated or softened to the desired degree before being stretched. It is also preferable not to release the film from the clamps 5 immediately after the stretching operation, but to pass it over a further portion 10 of the tank while the film is still under tension but the chains again travel parallel to one another. The film may thus be cooled by contacting its under-surface with a liquid at a lower temperature before it is released from the clamps. Varied degrees of softness may be imparted to the film while held by the clamps before, during, or after the stretching operation by treating different portions of the under-surface of the advancing film simultaneously with liquid or vapour at different temperatures, the tank 2 being divided into several compartments by transverse partitions. The upper surface of the film, particularly its marginal areas, may be treated at the same time as the undersurface with, for example, infra-red rays, or cool air, or may be thermally insulated. In an example, a continuously travelling film of a polyterephthalic acid ester of glycol of 250 microns thickness and 380 mm. width, formed by melt extrusion, is introduced into a stretching frame having an inside transverse dimension of 340 mm. at the entrance and a rate of film advance of 2 metres per minute. For the first 800 mm. the clamps of the frame are conveyed along parallel paths of travel, and in this zone water at 88 DEG C. is washed against the underside of the film. Subsequently the clamps are led along diverging tracks while advancing the film 1900 mm. the angle of divergence between each track and the median line between the tracks being about 12 degrees, and the underside of the film being washed with water at 78 DEG C. The film is finally led, while still clamped, a distance of 800 mm., the path of travel of the clamps being parallel and the transverse distance between the clamps being 1150 mm. During this final portion of its path of travel the film is not washed with water but is allowed to cool down until it is released from the clamps and leaves the stretching frame. In the second example a plasticised film of a mixed polyamide, obtained by polycondensation of 4 parts by weight of caprolactam and 6 parts by weight of the adipic acid salt of diamino hexane, is transversely stretched in a similar manner.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE805733X | 1954-04-09 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB805733A true GB805733A (en) | 1958-12-10 |
Family
ID=6722423
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB10363/55A Expired GB805733A (en) | 1954-04-09 | 1955-04-07 | Process of transverse stretching of films of thermoplastic material |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB805733A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5340518A (en) * | 1992-10-13 | 1994-08-23 | General Electric Co. | Method for corrugating sheet material |
CN112004653A (en) * | 2018-04-10 | 2020-11-27 | 恩资派尔工业有限公司 | Machine for stretching biaxially oriented tubular blown film by means of isostatic pressure water |
-
1955
- 1955-04-07 GB GB10363/55A patent/GB805733A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5340518A (en) * | 1992-10-13 | 1994-08-23 | General Electric Co. | Method for corrugating sheet material |
CN112004653A (en) * | 2018-04-10 | 2020-11-27 | 恩资派尔工业有限公司 | Machine for stretching biaxially oriented tubular blown film by means of isostatic pressure water |
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