CA1052516A - Process and device for the manufacture of sheeting - Google Patents
Process and device for the manufacture of sheetingInfo
- Publication number
- CA1052516A CA1052516A CA216,355A CA216355A CA1052516A CA 1052516 A CA1052516 A CA 1052516A CA 216355 A CA216355 A CA 216355A CA 1052516 A CA1052516 A CA 1052516A
- Authority
- CA
- Canada
- Prior art keywords
- sheeting
- tube
- calender
- extruded
- gap
- 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
Landscapes
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
PROCESS AND DEVICE FOR THE MANUFACTURE OF SHEETING
Abstract of the disclosure:
To produce sheeting from thermoplastic material a tubular sheeting is extruded, the tube is blown up by internal pressure to the desired diameter and flattened and the flat sheet obtained is fed to a calender. The device to carry out the process comprises an extruder with blow head, flatten-ing means and a calender.
Abstract of the disclosure:
To produce sheeting from thermoplastic material a tubular sheeting is extruded, the tube is blown up by internal pressure to the desired diameter and flattened and the flat sheet obtained is fed to a calender. The device to carry out the process comprises an extruder with blow head, flatten-ing means and a calender.
Description
1~5Z516 This invention relates to a process for the manufacture of sheeting from thermoplastic materials by calendering an extruded plastic sheet, and to a device for carrying out said process.
In the manufacture of sheeting from thermoplastic material the material is extruded through a slot die and the extruded sheet is fed to a calender. The plastic sheet emerging from the die is introduced into the entrance gap of the calender. As compared with the usual thickness of calen-dered sheets, the sheet emerging from the slot die is relatively thick. Thick sheets result, however, in an inhomogeneous and incompletely plasticized kneading mass in the first roller gap so that especially in a two roll calender the final sheeting shows flow marks and considerable differences in thickness.
According to German Offenlegungsschrift 2,216,926 attempts are made to eliminate the aforesaid defectiveness of the extruded sheets by passing the relatively thick and plastic sheeting emerging from the slot die of the extruder through several heated rollers rotating at different circum-ferential speeds whereby the thickness of the extruded sheeting is reduced to a greater or lesser extent before it is introduced into the entrance gap of the calender.
This process does not overcome, however, the further disadvant-ages resulting from the combination of extruder with slot die and calender for the manufacture of calendered sheeting. For instance, the breadth of the extruded sheet cannot be varied or at most it can be varied to a minor extent only. Since the breadth of the extruded sheet is determined by the breadth of the slot die, the die has to be exchanged each time an extruded sheet of a different breadth shall be calendered. Moreover, with the use of slot dies the edges of the extruded sheets and, hence, also of the calen-dered sheets, especially those of polyvinyl chloride and copolymers of vinyl chloride, often show discolorations resulting from a thermal decom-position of the plastic material due to high temperatures in the border zones of the slot die.
In the manufacture of sheeting from thermoplastic material the material is extruded through a slot die and the extruded sheet is fed to a calender. The plastic sheet emerging from the die is introduced into the entrance gap of the calender. As compared with the usual thickness of calen-dered sheets, the sheet emerging from the slot die is relatively thick. Thick sheets result, however, in an inhomogeneous and incompletely plasticized kneading mass in the first roller gap so that especially in a two roll calender the final sheeting shows flow marks and considerable differences in thickness.
According to German Offenlegungsschrift 2,216,926 attempts are made to eliminate the aforesaid defectiveness of the extruded sheets by passing the relatively thick and plastic sheeting emerging from the slot die of the extruder through several heated rollers rotating at different circum-ferential speeds whereby the thickness of the extruded sheeting is reduced to a greater or lesser extent before it is introduced into the entrance gap of the calender.
This process does not overcome, however, the further disadvant-ages resulting from the combination of extruder with slot die and calender for the manufacture of calendered sheeting. For instance, the breadth of the extruded sheet cannot be varied or at most it can be varied to a minor extent only. Since the breadth of the extruded sheet is determined by the breadth of the slot die, the die has to be exchanged each time an extruded sheet of a different breadth shall be calendered. Moreover, with the use of slot dies the edges of the extruded sheets and, hence, also of the calen-dered sheets, especially those of polyvinyl chloride and copolymers of vinyl chloride, often show discolorations resulting from a thermal decom-position of the plastic material due to high temperatures in the border zones of the slot die.
- 2 -A
~OS~5~
This invention relates to a process for the manufacture of sheeting from thermoplastic material by extruding thermoplastic material in a thermoplastic state into the gap of a calender roller which extruded thermo-plastic material is heated up to temperatures which are maintained within the thermoplastic temperature range of the material, while maintaining an amount of kneading mass in the gap, which comprises the following steps:
(a) extruding the thermoplastic material through an annular orifice in the form of a tube;
(b) expanding the tube to a predetermined dimension for obtain-ing a desired sheeting width by interiorly supplying air while maintaining the tube at a substantially thermoplastic tempera-ture, (c) flattening the expanded tube to the desired width by passing it through squeeze rollers, the surface of at least one of which is covered with an elastomeric material; and (d) feeding the flattened tube into the gap of calender rolls, while maintaining a rolling kneading mass in the gap, for calen-dering it into single sheet.
This invention also relates to a device for the manufacture of sheeting from thermoplastic material comprising an extruder for extruding a tubular sheeting and a calender, wherein the extruder is provided with a blow head and between the blow head and the calender known flattening means are installed.
The present invention provides a process for the manufacture of sheeting from thermoplastlc materials, especially of polyvinyl chloride and copolymers of vinyl chloride, by calendering an extruded plastic sheet, which comprises extruding a tubular sheeting, blowing up the tube to the desired diameter under gas pressure, flattening the tube and feeding the extruded sheet obtained to the entrance gap of the calender.
The present invention further provides a device for the manu-facture of sheeting of thermoplastic material comprising an extruder and a calender, wherein the extruder carries a blow head and flattening means are ~ - 3 -10S;~i16 installed between the blow head and the calender.
The tubular sheeting is blown and flattened by known processes.
The tube is suitably flattened in usual manner by guide rolls and a pair of squeeze rollers. It is immaterial whether the two halves of the tube are welded together or they slightly adhere to each other, provided that the tube is flattened without folds and no gas bubbles are enclosed, which would detrimentally affect the surface quality of the finished sheeting.
This can be ensured by known means by using at least one squeeze roller having an elastic surface, for example of - 3a -1(~5'~5~6 rubber or a plastic material such as polytetrafluoroethylene, and by maintaining a sufficient pressure between the two rollers.
The internal pressure necessary to blow up the tubular sheeting emerging from the blow head is produced in known manner, for example by supplying a gas, such as air or nitrogen, through the blow head. The diameter of the expanded tube can be approximately one to five times the diameter of the blow nozzle. This large diameter range is possible because no special quality demands are made on the extruded sheet.
The temperature of the extruded tubular sheeting~ which varies in the range of from 100 to 250 C depending on the type of the thermoplastic material used~ should be substantially maintained until the extruded and flattened tube is seized by the calender rolls. To this effect the distance between the blow nozzle and the pair of squeeze rollers should be kept as short as possible. A variation of the distance by shifting the extruder and/or the pair of squeeze rollers and the guide rolls in axial direction proved to be particularly advantageous. To maintain the temperature of the extruded sheet at least one of the two squeeze rollers is preferably provided with heating means.
The extruded ~heet is calendered on usual roll systems or calenders under conditions known for thermoplastic materials.
~ Within the scope of the present invention the term "thermo-plastic materials" is intended to include quite generally all thermoplasts as far as they can be processed to yield extruded and blown tubular sheeting and calendered flat sheeting.
Especially good results are obtained with homopolymers of vinyl ~S;Z5J ~
chloride, copolymers of vinyl chloride with other suitable monomers and graft polymers on the bases of vinyl chloride or polyvinyl chloride as well as mixtures of the aforesaid polymers.
As compared to the known processes and devices for the manufacture of calendered sheeting~ the process and device according to the invention are distinguished by a number of advantages.
The combination according to the invention of extruder with blow head, means to adjust the internal pressure, flatten-ing means for the e~truded tubular sheeting and calender permits to supply the calender with homogeneously plasticized extruded sheets of different thickness and breadth and to produce on the calender final sheetings of different breadth the edges of which need no cutting or a very small cutting only. Hence, calendered sheeting of almost any desired breadth can be directly obtained without noteworthy waste.
The combination according to the invention also ensures the desired uniformity of the bank of kneading mass in the first calender gap which is particularly advantageous for the mechanical and physical properties of the final sheeting.
Good results are obtained not only with calenders composed of three or more than ~hree rolls but also and especially with a two roll calender as used frequently for the manufacture of sheetings of varying breadth. By means of the blowing process extruded tubular sheetings of different diameters can be produced which are thoroughly plasticized and homogeneous before they are introduced into the calender.
A further advantage of the combination according to the l(~SZ5~6 invention resides in the higher production rate due to the possible higher speed of the calender rolls.
The invention will now be described in further detail by way of example with reference to the accompanying drawings in which Figure 1 is a side view of a de~ice according to the invention and Figure 2 is a top view of the device shown in Figure l.
Extruder (1) is provided with a blow head (2). The molten plastic material emerging from the annular orificé of the blow nozzle (3) is blown up to a tubular sheeting (4) by the supply of air, generally through the blow head, and after a short distance (a) the tube is flattened by guide rolls (S) and squeeze rollers (6) and (7). The diameter of the extruded tube or the breadth (b) of the flattened sheeting (8) which is identical with the maximum breadth of the finished sheeting (13) after cutting off the edges (14), is adjusted by the internal pressure. After having passed squeezing rollers (6) and (7) the extruded sheet (8) is supplied with constant breadth to calender rolls (10) with gap (lOa) wherein a cylindrical bank of kneading mass (9) is formed.
Squeezing roller (6) is a steel roll with ad~ustable speed or rotation which is provided with heating means to maintain the temperature of the extruded sheet. To avoid the inclusion of air bubbles in the flattened extruded tube (8) roller (7) has a rubber surface. Roller (6) and roller (7) are pressed against each other.
The distance (a) between the blow head and the pair of squeeze rollers can be varied by moving extruder (1) in axial ~0~ 922 ~05'~516 direction on a frame not shown.
Rollers (10) forming gap (10 a) are provided with drives with adjustable speed of rotation and adjustable heating mean~
~he sheeting is withdrawn over draw-Off roll (11) and the edges are cut by knives 12. ~he trimmed sheeting (13) is wound up in usual manner.
~OS~5~
This invention relates to a process for the manufacture of sheeting from thermoplastic material by extruding thermoplastic material in a thermoplastic state into the gap of a calender roller which extruded thermo-plastic material is heated up to temperatures which are maintained within the thermoplastic temperature range of the material, while maintaining an amount of kneading mass in the gap, which comprises the following steps:
(a) extruding the thermoplastic material through an annular orifice in the form of a tube;
(b) expanding the tube to a predetermined dimension for obtain-ing a desired sheeting width by interiorly supplying air while maintaining the tube at a substantially thermoplastic tempera-ture, (c) flattening the expanded tube to the desired width by passing it through squeeze rollers, the surface of at least one of which is covered with an elastomeric material; and (d) feeding the flattened tube into the gap of calender rolls, while maintaining a rolling kneading mass in the gap, for calen-dering it into single sheet.
This invention also relates to a device for the manufacture of sheeting from thermoplastic material comprising an extruder for extruding a tubular sheeting and a calender, wherein the extruder is provided with a blow head and between the blow head and the calender known flattening means are installed.
The present invention provides a process for the manufacture of sheeting from thermoplastlc materials, especially of polyvinyl chloride and copolymers of vinyl chloride, by calendering an extruded plastic sheet, which comprises extruding a tubular sheeting, blowing up the tube to the desired diameter under gas pressure, flattening the tube and feeding the extruded sheet obtained to the entrance gap of the calender.
The present invention further provides a device for the manu-facture of sheeting of thermoplastic material comprising an extruder and a calender, wherein the extruder carries a blow head and flattening means are ~ - 3 -10S;~i16 installed between the blow head and the calender.
The tubular sheeting is blown and flattened by known processes.
The tube is suitably flattened in usual manner by guide rolls and a pair of squeeze rollers. It is immaterial whether the two halves of the tube are welded together or they slightly adhere to each other, provided that the tube is flattened without folds and no gas bubbles are enclosed, which would detrimentally affect the surface quality of the finished sheeting.
This can be ensured by known means by using at least one squeeze roller having an elastic surface, for example of - 3a -1(~5'~5~6 rubber or a plastic material such as polytetrafluoroethylene, and by maintaining a sufficient pressure between the two rollers.
The internal pressure necessary to blow up the tubular sheeting emerging from the blow head is produced in known manner, for example by supplying a gas, such as air or nitrogen, through the blow head. The diameter of the expanded tube can be approximately one to five times the diameter of the blow nozzle. This large diameter range is possible because no special quality demands are made on the extruded sheet.
The temperature of the extruded tubular sheeting~ which varies in the range of from 100 to 250 C depending on the type of the thermoplastic material used~ should be substantially maintained until the extruded and flattened tube is seized by the calender rolls. To this effect the distance between the blow nozzle and the pair of squeeze rollers should be kept as short as possible. A variation of the distance by shifting the extruder and/or the pair of squeeze rollers and the guide rolls in axial direction proved to be particularly advantageous. To maintain the temperature of the extruded sheet at least one of the two squeeze rollers is preferably provided with heating means.
The extruded ~heet is calendered on usual roll systems or calenders under conditions known for thermoplastic materials.
~ Within the scope of the present invention the term "thermo-plastic materials" is intended to include quite generally all thermoplasts as far as they can be processed to yield extruded and blown tubular sheeting and calendered flat sheeting.
Especially good results are obtained with homopolymers of vinyl ~S;Z5J ~
chloride, copolymers of vinyl chloride with other suitable monomers and graft polymers on the bases of vinyl chloride or polyvinyl chloride as well as mixtures of the aforesaid polymers.
As compared to the known processes and devices for the manufacture of calendered sheeting~ the process and device according to the invention are distinguished by a number of advantages.
The combination according to the invention of extruder with blow head, means to adjust the internal pressure, flatten-ing means for the e~truded tubular sheeting and calender permits to supply the calender with homogeneously plasticized extruded sheets of different thickness and breadth and to produce on the calender final sheetings of different breadth the edges of which need no cutting or a very small cutting only. Hence, calendered sheeting of almost any desired breadth can be directly obtained without noteworthy waste.
The combination according to the invention also ensures the desired uniformity of the bank of kneading mass in the first calender gap which is particularly advantageous for the mechanical and physical properties of the final sheeting.
Good results are obtained not only with calenders composed of three or more than ~hree rolls but also and especially with a two roll calender as used frequently for the manufacture of sheetings of varying breadth. By means of the blowing process extruded tubular sheetings of different diameters can be produced which are thoroughly plasticized and homogeneous before they are introduced into the calender.
A further advantage of the combination according to the l(~SZ5~6 invention resides in the higher production rate due to the possible higher speed of the calender rolls.
The invention will now be described in further detail by way of example with reference to the accompanying drawings in which Figure 1 is a side view of a de~ice according to the invention and Figure 2 is a top view of the device shown in Figure l.
Extruder (1) is provided with a blow head (2). The molten plastic material emerging from the annular orificé of the blow nozzle (3) is blown up to a tubular sheeting (4) by the supply of air, generally through the blow head, and after a short distance (a) the tube is flattened by guide rolls (S) and squeeze rollers (6) and (7). The diameter of the extruded tube or the breadth (b) of the flattened sheeting (8) which is identical with the maximum breadth of the finished sheeting (13) after cutting off the edges (14), is adjusted by the internal pressure. After having passed squeezing rollers (6) and (7) the extruded sheet (8) is supplied with constant breadth to calender rolls (10) with gap (lOa) wherein a cylindrical bank of kneading mass (9) is formed.
Squeezing roller (6) is a steel roll with ad~ustable speed or rotation which is provided with heating means to maintain the temperature of the extruded sheet. To avoid the inclusion of air bubbles in the flattened extruded tube (8) roller (7) has a rubber surface. Roller (6) and roller (7) are pressed against each other.
The distance (a) between the blow head and the pair of squeeze rollers can be varied by moving extruder (1) in axial ~0~ 922 ~05'~516 direction on a frame not shown.
Rollers (10) forming gap (10 a) are provided with drives with adjustable speed of rotation and adjustable heating mean~
~he sheeting is withdrawn over draw-Off roll (11) and the edges are cut by knives 12. ~he trimmed sheeting (13) is wound up in usual manner.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the manufacture of sheeting from thermoplastic material by extruding thermoplastic material in a thermoplastic state into the gap of a calender roller which extruded thermoplastic material is heated up to temperatures which are maintained within the thermoplastic temperature range of the material, while maintaining an amount of kneading mass in the gap, which comprises the following steps:
(a) extruding the thermoplastic material through an annular orifice in the form of a tube;
(b) expanding the tube to a predetermined dimension for obtaining a desired sheeting width by interiorly supplying air while main-taining the tube at a substantially thermoplastic temperature;
(c) flattening the expanded tube to the desired width by passing it through squeeze rollers, the surface of at least one of which is covered with an elastomeric material; and (d) feeding the flattened tube into the gap of calender rolls, while maintaining a rolling kneading mass in the gap, for calen-dering it into single sheet.
(a) extruding the thermoplastic material through an annular orifice in the form of a tube;
(b) expanding the tube to a predetermined dimension for obtaining a desired sheeting width by interiorly supplying air while main-taining the tube at a substantially thermoplastic temperature;
(c) flattening the expanded tube to the desired width by passing it through squeeze rollers, the surface of at least one of which is covered with an elastomeric material; and (d) feeding the flattened tube into the gap of calender rolls, while maintaining a rolling kneading mass in the gap, for calen-dering it into single sheet.
2. A process as claimed in claim 1, wherein the temperature of the extruded thermoplastic material is maintained between about 100 to 250° C
until the flattened tube is seized by the calender rolls.
until the flattened tube is seized by the calender rolls.
3. A process as claimed in claim 2, wherein the distance between the annular orifice and the squeezing rollers is minimized.
4. A process as claimed in claim 1, wherein the sheeting is made from polyvinyl chloride or a copolymer of vinyl chloride.
5. A process as claimed in claim 1, wherein the extruded and flat-tened sheeting is fed to a two roll calender.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19732362117 DE2362117B2 (en) | 1973-01-08 | 1973-12-14 | Data processing system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1052516A true CA1052516A (en) | 1979-04-17 |
Family
ID=5900707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA216,355A Expired CA1052516A (en) | 1973-12-14 | 1974-12-18 | Process and device for the manufacture of sheeting |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1052516A (en) |
-
1974
- 1974-12-18 CA CA216,355A patent/CA1052516A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 19960417 |