JPS5857297B2 - Pretreatment method for belt-shaped sheet for manufacturing roll-up sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pretreatment method for winding a strip of thermoplastic plastic, in which a mark is engraved on a flat strip of material, and the mark is applied to the winding of the strip of material. Serves as a spacing keeper between individual layers within the sheet,
As a result, a good flatness during the production of the strip material is maintained in the web even over long periods of time.

It is known to imprint, for example, so-called string-like marks on the edge of a strip-shaped sheet by means of a roll having a protrusion and a counterroll.

In this case, after the strip material has finished production and left the production machine, it is guided cold between this set of rolls, which push out the sheet material with their biting protrusions, so that small bulges are removed. Compress with a large force so that it occurs.

Depending on the thickness of the sheet, the shape of the protrusion, and the magnitude of the compressive force, this bulge protrudes slightly from the plane, thus forming a thick position with a certain thickness, and by continuously overlapping, the rolled sheet , and serves primarily to space the individual layers a little apart from each other in the area between the marks engraved on the edges.

In this way the surface of the sheet is generally protected.

This is because most areas of the surface of the layers are not in contact.

Although the disadvantages of the processing of strip materials belonging to this state of the art are individually small,1, overall, the clearly perceptible deviations of the sheet material produce a squeezing effect comparable to that of squeezing a copper plate into a curved shape. The problem lies in the occurrence of waveform distortion on the treated edges.

This deviation from the planar state of the strip material is caused by the fact that in the case of high-grade sheets, such as sheets used as base material cases for photo buttons and copying, or as recording materials, the quality of the manufactured product is mostly determined by the planar state. Not even one is allowed.

Furthermore, according to Belgian Patent No. 764,289, it is possible to apply different materials, e.g. wax mixtures, to the desired areas before winding, thereby creating thick positions between the individual layers in the wound sheet, which can also be influenced. A method of maintaining a constant interval has become known.

In this case, no disadvantageous deformation of the strip material occurs, but when the strip material is subsequently unwound for reprocessing, particles of foreign materials may be scattered and reach the service area of the strip material, which may cause coating defects or the like. may occur.

Therefore, great care is required in monitoring the reprocessing of this web sheet.

The application of wax mixtures, of course, additionally makes this web sheet expensive.

Furthermore, it is known from French Patent No. 2,110,951 to insert strips or filaments during winding which have a different coefficient of friction than the material to be wound, in the case of strip materials that are prone to block.

The disadvantages of this method, which do not otherwise concern maintenance of the flatness of the web, are the high additional costs for the stripping, unwinding and winding equipment, and the time lag from the usual change of the web. Continuous monitoring of this device is required for replenishment of empty take-up spools and continuous supply of suitable insert strips.

In the case of a recent group of known methods, the desired thick location within the strip material is obtained by appropriate shaping of the front film at the nozzle lip.

Clear disadvantages also arise in this case.

Slightly thicker strips in the strip material together with the strip material have to undergo different stretching processes during stretching, during which an even temperature distribution is disturbed and the strip spreads out differently in the transverse direction, so that the subsequent There is no overlapping during winding, and the stretching process produces excessive reinforcing effects that cannot be accurately captured by positive or negative deviations from the normal cross-section for various physical reasons.

Repeated use of a constant strip shape, and therefore always equal formation of the web, cannot be achieved with this method.

Therefore, the object of the present invention is to imprint a mark on a flat strip sheet so that the good flatness of the strip sheet obtained during production is not deteriorated and is maintained even after long-term storage in a rolled state. There is a relatively easy way to obtain this.

The objective is to create a pretreatment method for winding extruded flat strips of thermoplastic plastic, in which marks are engraved on both edges or at a distance from each edge. The problem is solved by a method characterized in that the sheet is stamped under full tension and then the strip sheet is subjected to a heat treatment under full tension.

Fully under tension means that the edges of the strip sheet are gripped and held when marking marks and during heat treatment.

Holding can be effected by known devices, such as rotating clamp chains, belts, etc.

The tension can be kept constant in this case, or it can also be increased, for example during the cutting or engraving of marks and during the heat treatment, which can be achieved, for example, by means of a diverging tenter frame.

Since at the same time there is always some longitudinal tension due to the feeding of the strip, this tension can be maintained at a value close to zero, but the requirement for an overall tension of the strip is guaranteed during the course of the method. .

Heat treatment refers to the heating and cooling process as described below in the specific implementation of the present method.

The advantages of the method according to the invention are obvious.

Precise transverse tension of the strip material, for example by clamps on the edges, and controlled longitudinal tension within the processing range enable ideal tension and smoothness when first imprinting the mark.

However, a further advantage lies in the subsequent heat treatment of the entire strip material in the subsequent steps of the strip material guidance, in order to maintain its perfect planarity.

The imprinting of the marks according to the invention and the subsequent heat treatment bring the strip material into an ideal planar state in practical operation.

In this case, the marks engraved according to the invention are fixed at the same time, and the small raised edges of the individual marks are heat treated without distortion.

During subsequent winding, the imprinted marks are superimposed one on top of the other, and a ring-like overall disk-like supporting structure is created in the wound sheet, with the mutual contact of the layers between the individual layers. A desired air film is formed that avoids contact, thereby protecting the strip material from, for example, scratch formation.

It has proven particularly advantageous to imprint the markings while the strip is in its tough state using the method of the invention.

The tough state indicates that the belt-like sheet is in a state that allows elongation in terms of its heat capacity.

This condition is obtained, for example, when the strip is heated by a previous extrusion or other pretreatment and can therefore be easily deformed.

The compressive force for imprinting the mark can be kept particularly low in this case.

According to another embodiment of the method, additional marks running parallel to one another are imprinted in the longitudinal direction.

Such measures are particularly advantageous when winding up very wide strips of material.

This is because the additional marks further support the layers of the sheet together.

If the wide strip sheet is to be subsequently divided into narrow strips, it is advantageous to inscribe the markings, particularly closely spaced from one another, such that the center between the two marks falls within the range of the subsequent division.

In this case, the distance between marks arranged correspondingly to each other is particularly 2
~50mm.

The method of the invention is generally applicable to sheets, in particular thermoplastic sheets, such as sheets of olefin polymers such as polyethylene, polypropylene, polyethylene terephthalate or mixed-or copolyesters, polyvinyl chloride, polystyrene, polyamides, etc. It has been found that this method is particularly effective when applied to sheets tempered by stretching.

In particular, the best physical properties of polypropylene, boria oxide, polyvinyl chloride, or polyethylene terephthalate, which are currently used in many fields, can be obtained by uniaxial or biaxial stretching.

In the case of such sheets, the book widening is carried out in particular by imprinting marks before stretching, and the stretching may be longitudinal or transverse stretching.

As an alternative to this, the markings can also be imprinted during the stretching process.

This is because in this case the sheet is in a tough state according to the drawing temperature.

The imprinting of the marks takes place in particular during the transverse stretching in this case.

This is because the sheet strip is already under full tension, for example by a clamp chain.

However, it is also possible to carry out one or more stretching processes first and only then to imprint the marks.

Particularly in this case, the imprinting of the mark is carried out after longitudinal-lateral stretching.

A further stretching, for example a final longitudinal stretching, can then be carried out.

The heat treatment of the invention carried out under full tension is carried out in the case of stretched strip sheets, such as polypropylene, polyester buttons and polyamide sheets, in particular at temperatures above the temperature of the extruded sheet.

This is because the desired end state, for example with respect to residual shrinkage, is thereby achieved very quickly.

However, in the case of unstretched strips or, for example, uniaxially stretched strips, the heat treatment is carried out at a temperature below the temperature of the extruded sheet.

Although the heat treatment is carried out at a constant temperature, it has been found that in many cases it is appropriate to carry out the heat treatment at ascending or descending temperatures in order to obtain certain desired physical properties of the final sheet.

Heat treatment is usually carried out under constant tension.

Particularly in the case of relatively deep markings, it has proven advantageous to increase the tension particularly in the lateral direction.

Although the width of the mark does not have to be particularly strict, it is actually advantageous to set the mark width to 1 to 30 mm, especially 5 to 15 cylinders, in order to maximize the yield of sheets required for later reprocessing. has become clear.

The depth of the mark also does not require a particularly strict value.

However, the depth of the mark is 1 to 20L (l) of the sheet thickness,
Particularly advantageous is 5 to 10%.

In some cases, for example, when it is intended to divide the strip sheet into one fixed length in the transverse direction, it may be desirable to imprint the marks in a non-continuous manner.

For that purpose the Act is equally appropriate.

This is because when looking at the marks in the vertical direction, it is possible to freely leave a certain range without marks.

The invention encompasses a web of sheet produced by winding a strip of sheet and treated by the method of the invention.

In particular, the thickness of 2~ produced by winding a strip sheet
101001t, especially a wound sheet of 10 to 50 μm.

Summary and embodiments of the present invention are listed below: 1) for the subsequent winding of extruded flat strip sheets of thermoplastics, particularly at or near the edges of the strip; Manufacture a roll-up sheet characterized by a continuous pretreatment method in which a mark is imprinted on each area, the mark is imprinted under full tension on the strip sheet, and then heat treatment is performed under full tension. Pretreatment method for strip-shaped sheets.

2) The method of item 1 above, in which the mark is imprinted on the belt-shaped sheet in its toughness state.

3) Engraving additional marks running parallel to each other (1) above
- Method of Section 2.

4) In the case of a strip-shaped sheet that is to be divided before being wound up, the method described in items 1 to 3 above, in which two marks are each stamped at close intervals so that the center between the marks falls within the range of subsequent division.

5) The method of item 4 above, in which the two marks within the division range are separated by 2 to 50 mm.

6) The method of items 1 to 5 above, in which a mark is imprinted before stretching.

7) The method of item 6 above, in which the mark is engraved before longitudinal stretching.

8) The method of item 6 above, in which the mark is engraved before lateral stretching.

9) The method of items 1 to 5 above, in which a mark is imprinted during longitudinal stretching.

10) The method of items 1 to 5 above, in which a mark is imprinted during lateral stretching.

11) The method of items 1 to 5 above, in which the mark is imprinted after one or multiple stretching steps.

12) The method of item 11 above, in which the mark is engraved after longitudinal-lateral stretching.

13) The method of items 1 to 12 above, wherein the stretched strip sheet is heat-treated at a temperature higher than the temperature of the extruded sheet.

14) The method of items 1 to 12 above, wherein the heat treatment is performed at a temperature lower than the temperature of the extruded sheet.

15) The method of items 13 to 14 above, wherein the heat treatment is performed at an increasing temperature.

16) The method of items 13 to 14 above, wherein the heat treatment is performed at a decreasing temperature.

17) The method of items 1 to 16 above, in which the heat treatment is carried out under tension, particularly increasing in the lateral direction.

18) The method of items 1 to 17 above, in which a mark having a width of 1 to 30 nIm1, particularly 5 to 15 n1m, is engraved.

19) The method of items 1 to 18 above, in which a mark having a depth of 1 to 20%, particularly 5 to 10%, of the sheet thickness is imprinted.

(additional) The method described in items 1 to 19 above, in which the mark is not printed continuously but with a blank area in the middle.

21) A rolled sheet produced by the method of items 1 to 20 above and obtained by winding up a strip sheet that is optionally divided into narrow strips.

Claims (1)

[Claims] 1. In a continuous preparation method for the subsequent winding of extruded flat strips of thermoplastic plastics, marks are imprinted on each edge of the strip or in the vicinity of the edge. 1. A method of preparing a strip sheet for producing a rolled sheet, characterized in that the strip sheet is stamped under full tension and then heat treated under full tension.