GB1576716A - Creping of laminated materials - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO THE CREPING OF LAMINATED MATERIALS (71) We, HENRY COOKE LIMITED, a British Company of Waterhouse, Mills, Beetham, Milnthorpe, Cumbria, do hereby declare the invention, for-which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to the creping of web materials, e.g. of laminates of paper, plastics material and metal foil.

Continuous creping requires the application of presusre at least to retard and deform the input web material. In one known process web material is creped by passing it through a treatment zone having a converging part to compress the material between a drive surface and a pressure applying means, which normally includes a web material contacting or pressing member and a presusre member arranged by substantially line contact therebetween to press the web material contacting or pressing member towards the drive surface, and then web material expanding retarding zone part normally -comprising rigid and flexible members.

In the creping of laminates, at least in such a process, there is a tendency with some laminates, because of the nature of somi: individual layers, for one layer to tear away from an adjacent layer-during the compressional treatment. This is particularly noticeable where one of the layers is metal foil, e.g., aluminium foil which is adhered to a plastics material, e.g. a polyethylene sheet; where the tendency to tear away, say because of the somewhat weak nature of the adherence, can result in pinholes in the metal foil surface and other localised or general delaminaiton after the compressional treatment.

It is an object of the invention to reduce such tendencies.

According to a first aspect of the invent tion there is provided a creping process wherein web material is creped by compression between pressure applying means and web material feed means and subsequent retardation, and there is interposed between the pressure applying means and the web material a continuous, resilient, cushioning sheet of material past 'which the web material slips as it is fed by the web material feed means, the sheet of resilient cushioning material having a surface struc ture aiding accommodation of dirt, dust or grit from the web material.

According to a second aspect of the invention there is provided an apparatus for creping web material comprising web material feed means and means for applying pressure to web material against said feed means at a creping position, and, interposed between the pressure applying means and the feed means at the creping position, a continuous, resilient, cushioning sheet of material past which the web material slips as it is fed by the web materal feed means, the sheet of resilient, cushioning material having a surface structure aiding accommodaion of dirt, dust or grit from the web material.

It is preferred that at least the web surface to contact said sheet is cleaned prior to presentation to the creping zone. For an aluminium surfaced laminate, this may be done by electrically earthing the aluminium and blowing off dust and dirt.

,In its application to the above-mentioned known process one embodiment of the invention provides for said sheet to extend through the web material compressing zone and the subsequent retarding and web material expansion zone. The pressure applying means may include resilient blade or plate means biassed to compress and then to retard the web material with creped expansion thereof. The feed - means will usually be a ribbed or rough surfaced roller to grip the material.The sheet of resilient cushioning material may be fixed in posi : tion but free from'iehe pressure' applying means at the creping positions, -perhaps arranged to be moved stepwise in between creping operation, or may be moved during treatment, say at a much reduced speed in relation to that of the laminate.

The cushioning effect has two aspects, firstly to accommodate any residual dirt; dust or grit say by way of resilient deformation embodiment, or even in pores, interstices or surface depressions, and secondly to smooth transition past any edges of the'p"ressure applying means which is typicaly a sheet or sheets of spring steel, which, for a multiple structure, where one serves to compress and another to retard, may be overlapped and produce- a sharp' edge or corner at the transition from one to the other. Such sheet steel systems normally operate relative to a rigid doctor blade.

A particular suitable cushioning layer or sheet is a spun bonded polyethylene sheet, a cbmmercially available polyethylene paper like material of this kind being sold under the Registered Trade Mark "TYVEK".

However, other materials such as poly propylenè may be used so long as they.

are of suitable strength and surface slipperi ness, súch as close-textured sheets having a pore structure.

It is appreciated that the term "slippery" is- a relative one and a minimum require ment is that friction thereat should not interfere with driving the laminate, typist ally by friction with a drive roller. Merely coating a multiple bladed pressure applying compressing and retarding mechanism, even with Teflon (Registered Trade Mark), is not, on its own, adequate to prevent spoiling laminates, particularly aluminium coated laminates.However, the use of a separate layer to smooth any transitions in the creping zone does improve matters even where its surface slipperiness is less than that of Tefion, though it clearly must not have any marked tendency to grip the laminate surface, whatever its nature, at the working .pressures, which may vary according to the type and thickness of the laminate. The " slipperiness " of area bonded, spun-bonded TYVIK.with a base weight of-80gms/square metre has been estimated by way of coefficient of friction between two layers thereof-found to be about 0.2-and this has proved to be very satisfactory in operation.

One particular embodiment of the in vention is described below with reference to the accompanying diagrammatic sketch.

A laminate 10 consisting of kraft paper, polyethylene sheet and aluminium foil is fed into a converging treatment zone 11 between the drive roll 12, rotating in the direction of the arrow A and having a gripping surface 12a formed by helical ribs and grooves or by a rough surface coating, and a material pressing member of spring metal plates or sheets 13 and 14. The upper spring metal plate or sheet 14 extends beyond the edge of the lower spring metal plate or sheet 13 providing a part 14a which acts as' a flexible resilient retarder member. A relatively rigid retarder. member .15 in. the form of a doctor blade forms with part 14a the retarding zone 18 through which the laminate travels in the direction of the arrow B.A pressure member 16 acts via a further plate 20 co-operating with the plates or sheets 13, 14 in location thereof by a clamp 21 and is suitably in the form of a plate-projecting from its mounting as a cantilever to provide a continuous straight pressing edge-parallel to the axis of the drive roll .12.A sheet 17 of "TYVEK" polyethylene sheet is located between the plate or sheet 13 and the laminate 10 specifically by the clamp 21 and extends at least to the end of the retarding zone adjacent to the flexible retarding member 14a; The cushioning effect of sheet 1-7 in the zone between-the line of the pressing edge of member 16 and the end of the retarding zone acts to prevent--substantially any tear ing away of the :strata of the laminate likely to occur otherwise.during the compressional treatment in the said zone. If desired the sheet need not be permanently anchored but may be indexable from a supply roll at intervals to present a fresh length in the treatment 'zone, or maybe in endless form, possibly with a cleaning station along its path of movement and may also be indexed.In either of the latter cases continuous movement may be pre ferable, say at a speed not exceeding that of the laminate A laminate surface 'cleaning station is shown at 25 specifically for aluminium sur faced laminate and comprising an earthing electrode or electrodes 26, an angled air nozzle or jet arrangement 27, usually a multi-jet assembly, fed with compressed air over line 28, and a hood-like housing 29 therefor that has a suction line 30 attached for dirt removal. Other cleaning operations, say using brushes, sponges or baths, are possible, say for other laminates, such as kraft paper'sandwiches. Regarding the latter, one laminate on which very good results have been obtained has wax ad hesive and polypropylene thread or mesh intermediate outer kraft paper layers.

WHAT WE CLAIM IS: - 1. A creping process wherein web material is creped by compression between pressure applying means and web material

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. to grip the material. The sheet of resilient cushioning material may be fixed in posi : tion but free from'iehe pressure' applying means at the creping positions, -perhaps arranged to be moved stepwise in between creping operation, or may be moved during treatment, say at a much reduced speed in relation to that of the laminate. The cushioning effect has two aspects, firstly to accommodate any residual dirt; dust or grit say by way of resilient deformation embodiment, or even in pores, interstices or surface depressions, and secondly to smooth transition past any edges of the'p"ressure applying means which is typicaly a sheet or sheets of spring steel, which, for a multiple structure, where one serves to compress and another to retard, may be overlapped and produce- a sharp' edge or corner at the transition from one to the other. Such sheet steel systems normally operate relative to a rigid doctor blade. A particular suitable cushioning layer or sheet is a spun bonded polyethylene sheet, a cbmmercially available polyethylene paper like material of this kind being sold under the Registered Trade Mark "TYVEK". However, other materials such as poly propylenè may be used so long as they. are of suitable strength and surface slipperi ness, súch as close-textured sheets having a pore structure. It is appreciated that the term "slippery" is- a relative one and a minimum require ment is that friction thereat should not interfere with driving the laminate, typist ally by friction with a drive roller. Merely coating a multiple bladed pressure applying compressing and retarding mechanism, even with Teflon (Registered Trade Mark), is not, on its own, adequate to prevent spoiling laminates, particularly aluminium coated laminates.However, the use of a separate layer to smooth any transitions in the creping zone does improve matters even where its surface slipperiness is less than that of Tefion, though it clearly must not have any marked tendency to grip the laminate surface, whatever its nature, at the working .pressures, which may vary according to the type and thickness of the laminate. The " slipperiness " of area bonded, spun-bonded TYVIK.with a base weight of-80gms/square metre has been estimated by way of coefficient of friction between two layers thereof-found to be about 0.2-and this has proved to be very satisfactory in operation. One particular embodiment of the in vention is described below with reference to the accompanying diagrammatic sketch. A laminate 10 consisting of kraft paper, polyethylene sheet and aluminium foil is fed into a converging treatment zone 11 between the drive roll 12, rotating in the direction of the arrow A and having a gripping surface 12a formed by helical ribs and grooves or by a rough surface coating, and a material pressing member of spring metal plates or sheets 13 and 14. The upper spring metal plate or sheet 14 extends beyond the edge of the lower spring metal plate or sheet 13 providing a part 14a which acts as' a flexible resilient retarder member. A relatively rigid retarder. member .15 in. the form of a doctor blade forms with part 14a the retarding zone 18 through which the laminate travels in the direction of the arrow B.A pressure member 16 acts via a further plate 20 co-operating with the plates or sheets 13, 14 in location thereof by a clamp 21 and is suitably in the form of a plate-projecting from its mounting as a cantilever to provide a continuous straight pressing edge-parallel to the axis of the drive roll .12.A sheet 17 of "TYVEK" polyethylene sheet is located between the plate or sheet 13 and the laminate 10 specifically by the clamp 21 and extends at least to the end of the retarding zone adjacent to the flexible retarding member 14a; The cushioning effect of sheet 1-7 in the zone between-the line of the pressing edge of member 16 and the end of the retarding zone acts to prevent--substantially any tear ing away of the :strata of the laminate likely to occur otherwise.during the compressional treatment in the said zone. If desired the sheet need not be permanently anchored but may be indexable from a supply roll at intervals to present a fresh length in the treatment 'zone, or maybe in endless form, possibly with a cleaning station along its path of movement and may also be indexed.In either of the latter cases continuous movement may be pre ferable, say at a speed not exceeding that of the laminate A laminate surface 'cleaning station is shown at 25 specifically for aluminium sur faced laminate and comprising an earthing electrode or electrodes 26, an angled air nozzle or jet arrangement 27, usually a multi-jet assembly, fed with compressed air over line 28, and a hood-like housing 29 therefor that has a suction line 30 attached for dirt removal. Other cleaning operations, say using brushes, sponges or baths, are possible, say for other laminates, such as kraft paper'sandwiches. Regarding the latter, one laminate on which very good results have been obtained has wax ad hesive and polypropylene thread or mesh intermediate outer kraft paper layers. WHAT WE CLAIM IS: -

1. A creping process wherein web material is creped by compression between pressure applying means and web material

feed means and subsequent retardation, and there is interposed between the pressure applying means and the web material a continuous, resilient cushioning sheet of material past which the web material slips as it is fed by the web material feed means, the sheet of resilient, cushioning material having a surface structure aiding accommodation of dirt, dust or grit from the web material.

2. A process as claimed in claim 1, wherein said sheet is caused to extent at least through both a web material compression zone and a following retarding zone allowing creped expansion of the web material.

3. A process as claimed in claim 1 or 2, wherein the web material is a laminate.

4. A process as claimed in claim 3, wherein the laminate is aluminium surfaced.

5. An apparatus for creping web material comprising web material feed means and means for applying pressure to web material against said feed means at a creping position, and interposed between the pressure applying means and the feed means at a creping position, a continuous, resilient, cushioning sheet of material past which the web material slips as it is fed by the web material feed means, the sheet of resilient, cushioning material having a surface structure aiding accommodation of dirt, dust or grit from the web material.

6. An apparatus as claimed in claim 5, wherein the pressure applying means includes resilient blade or plate means biassed to compress and then to retard the web material with creped expansion thereof, and said sheet extend throughout zones of web material compression and retardation.

7. An apparatus as claimed in claim 5 or 6, wherein said sheet is fixed in position but free from the pressure applying means at the creping position.

8. An apparatus or process as claimed in any preceding claims, wherein a web material cleaning station or step precedes the creping.

9. An apparatus or process as claimed in any preceding claim, wherein said sheet is of spun-bonded synthetic resin material.

10. An apparatus or process as claimed in claim 9, wherein said material is polyethylene.

11. A creping process substantially as hereinbefore described with reference to the accompanying drawing.

12. An apparatus for creping web material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.