AU633881B2 - Process for the adhesive binding of paper layers - Google Patents

Abstract

The method for binding bundled paper sheets 13 is based on an injection of adhesive into the paper sheets. This injection 15 of adhesive can consist of pressing the adhesive into the paper sheets which have been previously perforated by needles 22, the perforation being undertaken either in advance or in the same work process by means of injection by hollow or channelled needles 22. Another possibility of injection 15 of adhesive is based on the inclusion of drops of adhesive. The subsequent treatment 16 of the paper sheets can consist of pressing and/or the effect of ultrasound. If appropriate, the injection of adhesive is undertaken only into the inside sheets 52 of the paper sheets 13 without a cover sheet 51 and centre sheet 53. <IMAGE>

Description

633881 AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION Form

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: FERAG AG Address of Applicant: Zurichstrasse 74, 8340 Hinwil,

SWITZERLAND

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: PROCESS FOR THE ADHESIVE BINDING OF PAPER LAYERS.

The following statement is a full description of this invention including the best method of performing it known to me:- -la- Proce ,3 for the adhesive binding of paper layers.

The invention relates to a process and to an apparatus for the adhesive binding of paper layers.

Processes for joining paper layers have been known for decades.

They form an essential part of bookbinding. Innovations in connection with the mechanical binding of paper layers became necessary with the arrival of high-performance printing plants able to produce up to 100,000 printed products every hour.

Wire stitching and adhesive binding have proved satisfactory for the mass binding of paper layers, such as is required in printing works. Wire stitching is very important for the joining of printing material in booklet or brochure form. Rotary wire stitchers have a high efficiency, but are relatively expensive. A stitched copy can have up to 100 pages. In the case of rotary wire stitchers the wire staples are forced through the spread out paper bundle against an abutment and without any locking mechanism. The paper is folded after stitching.

Single or individual wire stitchers have a lower capacity per unit of time than rotary wire stitchers and are also expensive. However, the product can have over 300 pages and individual wire stitchers have an abutment with a locking mechanism.

I An advantage of wire stitching is the possibility of completely opening the booklet. There is no closed folded edge, which covers part of the printed information. However, a disadvantage of wire stitching is the material application through the staples in the back, which limits the stackability of the products. Additional costs also result from the selection, storage and processing of the appropriate wire material. There are also limits on the reliability of wire stitching, particularly in the case of thick paper layers having more than 200 pages.

2 Adhesive binding is a further paper binding method, which is particularly used in bookbinding. When this method is used, the paper is initially bundled, overcut and subsequently its back is glued.

Although this method has long been known, problems still occur.

Decisive points in connection with the success of this binding method are e.g. the paper quality, the nature of the unit (text or text with pictures), the nature of the adhesive (dispersion or hot melt adhesive) and the wetability of the printed paper. The drying speed is particularly critical in this method, where the back is wetted.

This is a function of the thickness of the adhesive applied, the absorptivity and the degree of paper gluing. For example, air flows or high frequency electric fields are used for speeding up drying.

The adhesive can be applied either cold or at elevated temperature.

It has proved advantageous for increasing the adhesion surface to provide the back to be glued with channels or grooves by means of a cutter equipped with equidistantly positioned knives. It must be ensured that the adhesive applied as a melt or dispersion can be deposited in an optimum manner on the edge of the sheet.

Another adhesion process is fold adhesion. In this process the individual paper layers are initially individually applied with strip or spot-like adhesion points or splices and are subsequently joined under pressure, cf. e.g. German Patent 35 27 660 C2. Fold adhesion makes it possible to simultaneously join a maximum of 32 pages at the normal printing speed. However, the process requires an additional operation, together with a complicated, individual guidance of the individual paper sheets. It must in particular be ensured that the paper layers prepared for joining are not in premature contact. In this connection reference is made to an interesting solution by I. Kbbler, described in Swiss Patent 665 389 A5. Smearing of the adhesive applied by cyclically pressing the paper web against an adhesive-applying roller is prevented in that the paper web is guided by guide rollers or pulleys, which have cavities corresponding to the adhesive strips.

Another disadvantage of fold adhesion is that the printed product cannot be completely opened in the fold. Pictorial information can be lost in the case of double-sided illustrations in booklets and brochures.

It is also known to join layers of paper by piercing the layers with a sharp instrument, such as a hollow needle, and filling the holes formed by the piercing process with a hardenable liquid binder. However, such methods require special tools to pierce the layers of paper and tools to cover the holes with the liquid binder.

Thus, the problem exists of developing a process permitting a simultaneous adhesion of paper layers, without having to accept the disadvantages such as the cutting open of the back prior to gluing, or the gluing of the individual pages prior to joining, or the use of sharp instruments to pierce the paper layers before gluing.

The present invention attempts to overcome one or more of the above problems.

According to the present invention there is provided a method for joining layers of paper to form a book, booklet or brochure comprising the steps of assembling a plurality of paper layers into a stack, propelling from a location above the top layer of the stack a series of droplets of a liquid binder into the stack with sufficient force to penetrate the stack and to wet all the paper layers underneath said location and pressing the layers at least in the wetted area of the stack together to adhesively join the layers.

Thus, the proposed process differs significantly from

I

existing adhesive binding processes, in which the adhesive is applied to the cut open back. Although these standard methods permit an optimum spreading of the adhesive, e.g.

through the application of grooves and the open back can also be subject to rapid adhesive drying, e.g. by hot air supply irradiation, etc,. but back gluing, as stated, requires a considerable amount of preparation.

The novel binder injection process of the preferred embodiment of the present invention also differs significantly from the aforementioned fold adhesion.

Whereas in the latter case, the individual sheets have to be individually provided with an adhesive and care must be taken to prevent any uncontrolled contact thereof prior to joining, in the method of the preferred embodiment of the invention the binder may be applied centrally to a sorted and ordered paper stack.

According to the present invention there is further 2C provided an apparatus for joining together a plurality of layers of paper assembled into a stack comprising the combination of a source of a liquid binder, means for propelling a series of droplets of said liquid binder from said source into said stack from a location above the top layer of the stack with sufficient force so that said droplets penetrate the whole stack and wet said layers and means for pressing said layers together along said line after said binder has been propelled into the stack.

Compared with wire stitching, the preferred embodiments of the binder injection process have a number of advantages.

There is no need for a precisely adjusted, wear-prone mechanism for pressing in and bending over the staples. It is merely necessary to slightly press the adhesive in the

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V area round the splice. Apart from the paper, no additional material (staple wire) has to be stored and supplied. The method is very advantageous from the recycling standpoint, because the paper has no extraneous matter (wire staples) and the necessary adhesive quantity is negligibly small.

It is possible to simultaneously process multilayer products. Foldability is improved by the moistening of the fold region with the binder.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 illustrates an example of a printing plant for producing mass printed material using binder injection into the paper layers.

Fig. 2 illustrates an apparatus for shooting droplets into the pape- layers.

Fig. 3 illustrates the principle of an apparatus for the separate treatment of the cover and middle sheet in the binder injection process.

In exemplified manner, Fig. 1 shows a printing plant with an integrated binder injection apparatus for paper layers.

The paper arrives from the paper loading means 10 at the printing means 11, which can comprise several printing stages and which also contains a cutting mechanism 12. The printing material is subsequently ordered and is then conveyed on in the form of bundled paper layers 13, optionally as a scale or flake flow 14. The printed matter then reaches the binder injection apparatus 15. The binder injection apparatus shoots droplets of liquid binder into the paper layers to bind the paper layers together. The scale flow 14 then passes into the after-treatment means 16. The bound products are then received from the removal means 17.

The principle of shooting binder droplets into paper layers is novel. It is a novel adaptation of the high-pressure water or water jet cutting method, which has been successfully used for separating solid materials, such as rock, metal, wood, plastic, etc. In this method the water is initially brought up to a pressure of several kbar and is delivered intermittently to the cutting nozzle. The ejected water droplets have an initial velocity of 600 to 1000m/sec.

The water jet cutting of paper has been investigated, but has been found unsuccessful. Contrary to expectations, a water jet striking paper layers dissolved after a short distance, the medium penetrating the paper layers and bringing about a swelling thereof, accompanied by an unsatisfactory cut quality. It is not therefore surprising that the water jet cutting method has not acquired any significance in the paper processing industry. It is therefore not obvious to use this method in conjunction with the binding of paper layers. However, the inadequacies of water jet cutting of paper, namely the disadvantageous consequences of wetting, swelling and mottling of the material are desired in connection with adhesion or bonding.

Fig. 2 shows an apparatus having a cylindrical casing 41 containing a booster plunger 42. As a result of its hydraulically controlled movement, the liquid medium supplied intermittently by the recharging valve 43 is intermittently shot into the material to be processed via nozzle 44 at a pressure of several kbar. The ejected droplets have an initial velocity of 600 to 1000m/sec.

A pressing device 27 may be used to prepress the paper layers 13, so that the kinetic energy of the medium droplets is not used up for the mechanical displacement of the paper layers 13 and is instead used for shooting through the droplets. As a result of the pressing, the paper layers are given a wood-like consistency (wood, e.g.

plywood can is known, be very adequately cut by water jets).

It is obvious that in this way water, even if it contains a little adhesive, can be shot into or through the fold. The paper layers 13 are slightly moistened. Binder is also introduced into the paper layers in the case of a dispersive or colloidal addition to the "cutting water".

As only a little binder is required, the binder concentration in the water jet can be kept very low, which prevents any risk of the nozzle clogging or eroding.

The paper layers are locally damaged in both binder injection modes. However, this damage can be rendered invisible, in that both the cover page of the booklet and possibly also the middle page are applied following binder injection. The binder passing out of the injection holes during the after-treatment ensures the adhesion of the cover and middle pages. A corresponding apparatus is shown in Fig. 3.

The cover page 51, the inner pages forming a unit 52 and without the middle page, as well as the middle page 53 are S supplied individually. The binder is injected in the b iI1I indicated manner into the unit 52. The three parts 51, 52, 53 are then joined together and after-treated, e.g. by means of an after-treatment device 16, 28.

In the case of a very sparing use of the binder, it should be possible to render the splice loadable by even short pressing. Another promising possibility for the drying, hardening and therefore quality increase of the splice consists of the use of ultrasonics, such as have been successfully used for joining plastics.

The stackability of the products can be improved in that, before or during folding, the fold is moistened slightly.

There is no need for such a treatment in the present process, because moistening occurs in conjunction with the binder injection.

The above preferred embodiment of the present invention is also advantageous over the method of piercing the layers of paper with a hollow needle and covering the resultant holes with liquid binder, since the need for a sharp instrument is not required and injection of the liquid binder can be done in one simple step.

(9

Claims (9)

1. 2. Method according to claim i, wherein the binder contains an adhesive.
2. 3. A method according to claim 1, wherein the wetted area of the stack is subjected to ultrasonic treatment.
3. 4. A method according to claim i, wherein the binder is propelled into the stack along a line and the stack is then folded along said line. A method according to claim 1, wherein after the binder has been propelled into the stack at least one cover page is added to the stack on the bottom or on the top of the stack.
4. 6. An apparatus for joining together a plurality of layers of paper assembled into a stack comprising the combination of a source of a liquid binder, means for propelling a series of droplets of 11 o "C I said liquid binder from said source into said stack from a loca- tion above the top layer of the stack with sufficient force so that said droplets penetrate the whole stack and wet said layers and means for pressing said layers together along said line after said binder has been propelled into the stack. 7 I 10
5. 8. Apparatus according to claim 7 comprising in addition means for an after-treatment cf the joined layers.
6. 9. Apparatus according to claim 8, wherein the means for after- treatment emits ultrasonic waves through the stack. An apparatus according to claim 6 wherein said means for pro- pelling includes a cylinder having a nozzle at one end there- of, a double-ended pressure piston within said cylinder having a first end directed toward said nozzle, means for supplying liquid binder from said source between said first end of said piston and said nozzle, and means for intermittently applying Shydraulic pressure to a second end of said piston to thereby eject droplets of said binder through said nozzle at high speed.
7. 11. An apparatus according to claim 10, wherein said high speed between about 600 m/sec and about 1000 m/sec.
8. 12. A method for ioining lavers of oaoer to form a book, booklet or brochure substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
9. 13. An aoparatus for joining together a plurality of lavers of oaoer assembled into a stack substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. DATED THIS 30TH DAY OF APRIL 1992 FERAG AG By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent SAttorneys of Australia. I