GB2041290A

GB2041290A - Laminating apparatus and method

Info

Publication number: GB2041290A
Application number: GB7903962A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-02-05
Filing date: 1979-02-05
Publication date: 1980-09-10

Abstract

The present invention provides a method of laminating comprising advancing a composite comprising a printed or otherwise marked sheet and a sheet of thermoplastic material through a laminating press comprising a platten and a stage and wherein at least one of the platten and the stage has a heated zone and a cooled zone respectively upstream and downstream to said composite as it advances through the press. The present invention also provides a laminating press comprising a platten 3 and a stage 2 and wherein at least one of the platten and stage has a zone 41 which, in use, is heated and a zone 42 which, in use, is cooled. <IMAGE>

Description

SPECIFICATION Apparatus and method FIELD OF THE INVENTION This invention relates to apparatus and method.

In a particular aspect, this invention relates to laminating apparatus and method.

BACKGROUND OF THE INVENTION It is known to take a printed or otherwise marked sheet and to laminate it with sheet plastics material for the purpose of, at least, protecting the marked sheet.

In one method, a first sheet of plastics material is laid, a printed or otherwise marked sheet is laid thereon and then a second sheet of plastics material is laid on the marked sheet.

The composite so formed is then subjected either to a hot press in a first press followed by a cold press in a second press or to a hot press in a first press which is subsequently cooled. It has also been the practice to press the whole area of the composite at one time.

SUMMARY OF THE INVENTION The present invention provides a method of laminating comprising advancing a composite comprising a printed or otherwise marked sheet and a sheet of thermoplastic material through a laminating press comprising a platten and a stage and wherein at least one of the platten and the stage has a heated zone and a cooled zone respectively upstream and downstream to said composite as it advances through the press.

The present invention also provides a laminating press comprising a platten and a stage and wherein at least one of the platten and stage has a zone which, in use, is heated and a zone which, in use, is cooled.

DESCRIPTION OF PREFERRED ASPECTS OF THE INVENTION It is preferred that the length of each of said heated zone and said cooled zone in the direction of advancement is substantially less than the length of said composite in said direction. As a result only part of the composite can be heated at any one time and this is considered to be positively beneficial.

It is preferred to advance the composite through the press in steps of length of two thirds or less, preferably about half or less, that of the length of said heated zone in the direction of advancement. This manner of advancement is beneficial in avoiding entrapment of air.

Conveyor apparatus is conveniently provided for advancing said composite.

A specific method and apparatus in accordance with this invention will now be described with the aid of the accompanying drawings.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS Figure 1 is a side elevational view of the apparatus, Figure 2 is a plan view of part of the apparatus, Figure 3 is a cross-section on line 3-3 in Figure 1, Figure 4 is a schematic view of part of the apparatus and Figure 5 is a cross-section on line 5-5 in Figure 2.

DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS Referring to the drawings, the apparatus shown therein comprises supports 1 and 2 for driven sprockets 4 and braked idler sprockets 6 and which, with supports 7 and 8, support a loading and unloading table 9 and a delivery table 11. The supports 7 also support idler sprockets 15 and the supports 1, 2 7 and 8 also support guide tables 16, 17 and 18. Guides 19 and 21 are also provided adjacent the sprockets 4 and 6. The supports 7 also support a press comprised of a stage 10 and a platten 3 which is vertically reciprocable as indicated by the arrow 5 in Figure 4.

Extending around the sprockets are two endless conveyor chains 61. Certain of the links (64) of the chains 61 carry metal plates 66, bolts 67, top plates 68 and wing nuts 69. The integers 66-69 serve to secure two polytetrafluorethylene coated woven fibreglass sheets 23 and 31 to the chains 61 and one end of each of those sheets 23 and 31 which is a leading end of the sheets 23 and 31 as they are advanced through the apparatus in the direction of arrow 25 by the chains 61. The other ends of the sheets 23 and 31, the trailing ends, are free.

Guides 12 are provided for rollers 14 carried by the chains 61.

The press is provided with a guide 70 to ensure that the sheets 23 and 31 are smoothly guided and do not foul the press. To guide 70 is secured a sheet of canvas 71 which serves as a heat and force distributing blanket.

The stage 2 has a rubber mat 72 on its upper surface to cushion pressing forces.

The platten 3 comprises a heated portion 41 and a cooled portion 42 each of about sixteen inches in length.

In use the sheets 23 are rolled up when on the table 9 which serves as a work table for the preparation of packages for pressing and for the removal of products.

With the sheets 23 rolled up packages (20) are prepared using the sheets 31 as bottom sheets.

Onto the sheets 31 are loaded product groups 24 each being a bottom sheet 26 of thermoplastic material, a printed or otherwise marked sheet 27 or other material to be laminated and a top sheet 28 of thermoplastic material. Thereafter the sheets 23 are unrolled to lie smoothly on the product group 24.

The conveyor chains 61 are then driven to advance the packages towards the press. The chains 61 are driven to advance the packages in eight inch steps which are thereafter followed by a dwell period. During the dwell the platten 3 is moved to press the respective package and the chains 61 and platten 3 are operated in synchronism. In consequence each eight inch unit of length of the package, and in particular the product group will undergo two heating stages followed by two cooling stages.

When each package has passed through the press it is carried on to the table 11 and thereafter onto, and to be supported by, the tables 1 6, 17 and 18 until it is returned to the table 9. The sheet 23 is then rolled up, conveniently on to a tube or pipe and the product group is removed.

The product so formed is illustrated in the drawings and comprises the sheets 23 and 28 bonded to the sheet 27 and to themselves at 30.

Thereafter a new product group may be loaded.

Referring now to the preferred nature of certain parts of the above described apparatus and method, the canvas sheet 71 and rubber pad 72 function as heat distributing materials and also as padding materials to distribute press forces and in so doing to closely conform about the product group. In this respect, if the product group 24 was merely pressed then bonding of the thermoplastic sheets outside the perimeter of the printed or otherwise marked sheet 27 (at 30) may not be satisfactory. Having regard to these functions, the canvas sheet and rubber pad may be replaced by other materials such as blankets.

The polytetrafluoroethylene coated woven fibreglass sheets 23 and 31 serve as release agents in that the thermoplastic sheets should not substantially bond thereto. An alternative release sheet may be used such as silicone rubber treated materials and certain sheet plastics materials.

In addition, the polytetrafluoroethylene coated woven fibreglass sheets can serve to texturize the thermoplastics sheets and the weave may be such as to produce a desirable pattern thereon.

The thermoplastic sheets 26 and 28 are of any convenient plastics material but preferred are uplasticized polyvinyl chloride of a vacuum forming grade which is capable of softening and bonding at a temperature of from 1 20--200"C.

One preferred thermoplastic sheet is heated to about 165 + 170C.

The printed or otherwise marked sheet 27 is preferably paper or card but other materials including those to which the thermoplastic sheet will not bond may be used. However, paper or card is most preferred as good bonding usually results.

It must be noted that some paper treatments 'such as those applying a paper sealing coating may reduce bonding and in particular photographs on resin coated paper may produce some bonding difficulties. Some bonding difficulties can be overcome by coating the paper with a plasticizer.

In general, however, any printed paper is usually easily bonded.

Concerning the press itself, the platten 3 is moveable and the stage 2 is stationary but could alternatively be a moveable platten. As described, the platten is provided with heating and cooling means but, alternatively or additionally, the stage could be provided with heating and cooling means.

The heating means may be electrical heating means. Alternatively, steam or heated oil may be passed through the platten. The cooling means is preferably cold water; refrigerated if necessary; or a refrigerant gas. Cold water at 00C to 250C is generally adequate.

The heating means should heat the platten in the region thereof to an extent sufficient to raise the temperature enough to soften the thermoplastic sheets to an extent at which bonding is obtained. This temperature is likely to be in the range 1200--2000C.

The cooling means should cool the platten in the region thereof substantially below that temperature but not necessarily to room temperature.

It will be appreciated that as well as heated and cooled zones there will also be an intermediate zone 40 in which the temperature varies from end to end.

The function of the heated zone is, as stated, to soften the thermoplastic sheets but, in addition, since the product group will normally be substantially longer than the length of advancement in each step and since that length is small, the heated zone will tend to drive any entrapped air towards the end of the product group which is yet to be heated and air entrapment becomes minimal.

The cool zone will serve to stabilize the thermoplastic sheets by positive cooling rather than merely by permitting cooling.

The pressure applied by the platten is desirably from 80 to 150 psi.

Modifications and adaptations may be made to the above described without departing from the spirit and scope of this invention which includes every novel feature and combination of features disclosed herein.

The claims form part of the disclosure of this specification.

Claims

1. A method of laminating comprising advancing a composite comprising a printed or otherwise marked sheet and a sheet of thermoplastic material through a laminating press comprising a platten and a stage and wherein at least one of the platten and the stage has a heated zone and a cooled zone respectively upstream and downstream to said composite as it advances through the press.

2. A method of laminating as claimed in claim 1, wherein the length of each of said heated zone and said cooled zone in the direction of advancement is substantially less than the length of said composite in said direction.

3. A method of laminating as claimed in claim 2, including advancing the composite in steps of length of two thirds or less that of the length of said heated zone in the direction of advancement.

4. A method of laminating as claimed in claim 2, including advancing the composite in steps of length of half or less that of the length of said heated zone in the direction of advancement.

5. A laminating press comprising a platten and a stage and wherein at least one of the platten and stage has a zone which, in use, is heated and a zone which, in use, is cooled.

6. A laminating press as claimed in claim 5, wherein means is provided to advance a composite comprising a printed or otherwise marked sheet of material and a sheet of thermoplastic material and wherein the length of the zones which, in use, are heated and cooled in use is substantially less than the length of the composite.

7. A laminating press as claimed in claim 6, including means for advancing the composite in steps of length of two thirds or less that of the length of the zone which, in use, is heated.

8. A laminating press as claimed in claim 7 including means for advancing the composite in steps of length of half or less that of the length of the zone which, in use, is heated.

9. A laminating apparatus as claimed in claim 6, wherein said means is adapted to advance said composite in step-wise manner and wherein means is provided to cause the platten and stage to press said composite synchronously after a step-wise advancement.

10. A method of laminating substantially as hereinbefore described with reference to the accompanying drawings.

11. A laminating apparatus substantially as hereinbefore described with reference to the accompanying drawings.

12. The articles, things, parts, elements, steps, features, methods, processes, compounds and compositions referred to or indicated in the specification and/or claims of the application individually or collectively, and any and all combinations of any two or more of such.,