JPH03108590A - Method and device for joining paper layer - Google Patents

Abstract

PURPOSE: To make it unnecessary for separate paper sheets to discretely undergo complicated preparation such as application of a strip of a binder, by using ultrasonic binding. CONSTITUTION: An ultrasonic generator 20 comprises an ultrasonic transformer 21 and a vibrating tool or a so-called sonotrode 24. The sonotrode 24 ensures transmission of ultrasonic power to a welding material 26 to be applied for binding at a tip 25. An abutment 27 absorbs a contact pressure released onto the material 26 by the end part of the sonotrode. By welding paper layers together by ultrasonic waves in this way, complicated preparation such as application of a strip of a binder to separate paper sheets is dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method of bonding layers of paper and to an apparatus for accomplishing the method.

Methods for bonding and also connecting layers of paper have been known for decades and form an essential part of bookbinding technology. With the advent of sophisticated printing equipment capable of producing up to 100,000 copies of printed products per hour, innovations in bonding paper layers became necessary.

For operations involving the binding of large numbers of layers of paper, such as those that occur in printing operations, adhesive binding, thread binding and wire binding or clasping have proven to be very satisfactory methods, in particular.

Adhesive binding is preferably used for binding books, catalogs and magazines. Often various adhesive methods are combined with each other. For example, a low-viscosity, high-moisture coating may be applied first, followed by a coating that improves adhesion. This makes it possible to greatly improve the quality of the binding compared to simpler methods.

In the case of adhesive bonding, the width to which the adhesive is applied is generally 4 mm. It is possible to bind approximately 15,000 copies per hour by bonding, and a considerable area in the production line must be provided for drying of the bonding agent. A significant disadvantage of this method is the drying time that must be given to the combined product.

In summary, adhesive binding can be considered as a successful method for binding books, catalogs and magazines.

However, with a few exceptions due to the necessary long drying times, this method does not require the use of scales or flake streams or flakes of separate paper layers in printed product processing machines.
It is less suitable for bundling booklets.

A further proven method for joining paper layers is thread binding, but it has been relegated to the background by adhesive joining. Only as a result of significant improvements in sewing capabilities, this method has again acquired significance. Thread binding has a number of advantages and disadvantages compared to adhesive binding. The quality of adhesive binding is highly dependent on the type of paper, but thread binding has little to do with paper quality.

As a relatively slow method, thread binding may be considered suitable for high quality binding of books.

However, the greatest importance was given to the sewing or clasping of printed matter in the form of bound books or booklets to wire binding or clasp binding. Rotary wire stitchers have high capacity but relatively high IilIit8.

A bound book can have up to 100 pages.

In the case of rotating wire binding, a wire clip or catch is pushed into the stack of paper spread out against the abutment point and it does not have a locking mechanism.

Single wire stitchers have a lower capacity per hour than rotating wire stitchers and are relatively expensive. However, the product can have over 300 pages. The single wire stitcher has a stitching abutment point with a locking mechanism.

The advantage of wire binding is the possibility of opening the booklet completely. There are no closed, folded edges that cover portions of printed information. However, a disadvantage of wire binding is the application of material through the rear clasp, which limits the stacking ability of the product. Moreover, additional costs arise from the selection, storage and processing of suitable wire materials. The reliability of wire binding also has its limits, especially with thick layers of paper exceeding 200 pages.

Thus, there is interest in a method that can be integrated into the printed product processing operation of a high performance printing press, that has an efficiency comparable to that of wire binding methods, but without its disadvantages such as the use of metals. It is something. When pursuing such methods, it is ensured that individual papers do not need to be individually subjected to complex preparation such as the application of strips of binder and also require buffering or intermediate storage times due to long drying periods. Particular care was taken to ensure that this was not the case.

The problem of this invention is therefore to provide a method for joining paper layers and avoids the disadvantages of known paper binding or binding methods. This problem is solved in that the paper layers to be bonded are bonded under the action of ultrasound according to claim 1 of the present invention.

Welding together layers of paper with ultrasound is not trivial.

Ultrasonic welding is explicitly known as a method for joining metals and plastics.

According to this method, the welding materials are heated under ultrasonic motion due to internal friction in their contact area so that there is melting of the materials to be joined and hence a weld is obtained. In this connection D-6056 Heusenstamm,
Published by Industrie Strasse 48 Planzonschallkraft G.M.B.R.
Altena, W.-R., Behnke, L., Holfert, H.
The publication “Ultrasonic J for Plastic Bonding” by OJ, Reinhardt and W, Ruland
shall f'ur das Kunsts
toff-Fugen).

Initially, it did not seem appropriate to use ultrasound to bond organic fiber materials such as paper, cardboard, 44 wood, woven and non-woven fabrics, as these materials are generally decomposes under ultrasonic heating and can even catch fire in the presence of oxygen. In particular, they cannot be brought into the liquid phase, which is necessary for welding.

However, our studies have demonstrated that only very thin coatings are required to ensure sufficient adhesion between the paper layers. This coating may be, for example, a printing ink applied during the printing process or a thin, rapidly drying plastic film. Optionally, suitable binders may be incorporated during paper manufacture. The simultaneous effects of heat, pressure and oscillatory motion
Even when the amount of binder is very small, it leads to good adhesion of the paper layers.

Although the joining of paper layers by bonding is known, said method requires the application of an adhesive to the product to be glued immediately prior to bonding. However, this requires the additional action of having to ensure that there is no premature contact between the papers that are individually applied with adhesive and also prepared to be bonded. However, the proposed ultrasonic method makes it possible to pre-treat the paper simultaneously with the actual printing for later bonding purposes, i.e. the pre-treatment method can be integrated into the printing process; In particular, further processing of the printed product, such as cutting the individual papers, arranging them and folding the paper layers, is not hindered or made more difficult by the bonding pre-treatment. It is particularly advantageous that the paper layers can be joined in a manner similar to wire binding or paper binding.

The invention will be described in more detail below with reference to non-limiting examples and the accompanying drawings.

FIG. 1 shows, in an exemplary manner, the structure of an ultrasonic device that can be used for welding plastics.

The control means 10 comprises a main part 11, an amplifier 12, a high frequency transformer 13 and a tunable positive feedback means 14 connected by a positive feedback key 15 to the inputs of the amplifier 12 and the transformer 13.
including. The frequency determining element of the ultrasound generator 20 is connected to a high frequency transformer. This circuit allows the ultrasonic generator 20 to perform
Ensures that it can be operated at acoustic resonance. By tuning the positive feedback means 14, the phase position of the high frequency oscillator can be optimized.

FIG. 2 shows the basic structure of the ultrasonic generator 20.

It generally includes an ultrasonic transformer 21 and a vibrating tool or so-called sonotrode 24.

The ultrasonic transformer 21 includes a stack of parallel-connected piezoceramic plates 22 . A sound amplitude transformer or booster 23 is optionally interposed between the ultrasound transducer and the sonotrode. This passive element 23 leads to an increase or decrease in the oscillation amplitude. The sonotrode, the actual connecting or joining tool, ensures the transmission of ultrasonic power to the welding material 26 to be joined at its tip 25. Abutment point 27 absorbs the contact pressure exerted by the sonotrode end onto material 26. The abutment point 27 must be constructed in such a way that it absorbs a minimum of the ultrasonic power applied, i.e. it must have a very high mechanical inertia and be very difficult to deform with respect to the welding material 26. .

The system including ultrasound transducer 21, booster 23 and sonotrode 24 operates in synchronized resonance. Longitudinal vibrations are excited in many applications. Ultrasonic welding equipment typically operates at frequencies of 20 to 40 KHz. The longitudinal vibration amplitude at the tip 25 of the sonotrode 24 is typically about 1100 u at 20 KHz and about 50 μm at 40 KHz.

The device including the control means 10 and the ultrasonic generator 20 generally operates independently of dampening by the welding material 26.
It is operated by the control system in such a way that the mechanical amplitude at the sonotrode end 25 has a constant predetermined value. In the case of a more advantageous ultrasonic welding machine, it is possible to predetermine, in addition to the ultrasonic power, the contact pressure exerted by the sonotrode end 25 on the welding material 26 and the ultrasonic operating time.

The selection of booster 23 and the shape of sonotrode 24 are a function of the welding material 26 and the nature of the welding performed. An example of the most standard sonotrode shape and format is R
-Altena, W. -R Behnke, L@Holfert,
as described in the aforementioned work "Ultrasound for Plastic Damage" by H.--J. Reinhardt and W. Ruhland.

Figures 3-5 illustrate some examples of sonotrodes that are particularly suitable for the uses discussed below. Thus, FIG. 3 shows a conical 31 sonotrode 24 suitable for obtaining point-like or spot welds.

FIG. 4 shows a sonotrode having a flat sonotrode end 41 and a knife-edge welded end 42. FIG. This embodiment of sonotrode 24 is particularly suitable for making long narrow welds.

FIG. 5 is a combination of the two embodiments of FIGS. 3 and 4. The flat sonotrode end 41 has a knife edge shape, as shown at 42 in FIG. However, a notch 53 is provided in the welding end 42 to increase the local contact pressure between the sonotrode 24 and the abutment point 27. In this way, the welding points can be made into long and narrow welding seams at the same time.

Using an apparatus such as that shown in FIGS. 1 to 5,
It is impossible to combine dry, unprinted paper layers. Corresponding tests only revealed a darkening or blackening due to the thermal action caused by ultrasound. A further step would allow the individual paper fibers to become entangled together during the ultrasonic operation, especially when the latter are oriented transversely to the paper surface. Such entanglements were also slightly detected in the case of longitudinal motion.

Even better results can be obtained by slightly moistening the paper layer. In this case the structure of the paper is slightly damaged, as occurs in paper manufacturing, forming a paper making stock locally. As in many paper manufacturing processes, the subsequent ultrasound-induced heating and compression leads to entanglement and bonding of the paper fibers. This essentially allows limited adhesion of the paper layers.

However, even better results can be obtained if the paper is provided with a dissolvable coating, although a very thin film is sufficient. Separate 2 where one is printed using standard printing ink and the other is not printed
Even on one paper layer, after ultrasonic operation there is a partial transfer of printing ink to unprinted pages. This means that the adhesion of the printing ink to the unprinted page is just as good as the adhesion during the original application. Strong printing, such as dark brown shadows on glossy paper, such as those found locally in illustrated magazines, leads to very good adhesion under ultrasonic action.

It is recommended that the paper be pre-processed to ensure a reliable connection. There are different possibilities in this regard.

FIG. 6 shows a sheet of paper that has been pretreated for ultrasonic welding. In the fold area 62 of the paper 61 a strip 63 delimited in the groove direction is defined and is provided with printing ink or a plastic that melts at higher temperatures. Such a strip 63 is a sheet of paper 6 into which later an insert page, entry or order form or art print is to be inserted.
may be applied additionally or alternatively to one area 64.

Both strip areas 63,64 can be applied to the paper 61 during the printing process, for example by multiple coatings using printing inks, in particular printing dyes containing a large amount of binder, or in an additional coating step.

Another pretreatment possibility for ultrasonic welding after the paper 61 consists of the undefined application of a colorless binder, for example a very thin plastic film. Such pre-treatment does not require changes to the printing process, for example by using special printing dyes.

Pre-treatment could be accomplished, for example, by spraying the printed pages in the binding area. In any case, the application of I-dye, which generally occurs in the fold area, will have little adverse effect due to the minimal application of material.

Further treatment of the paper consists in pre-treating the paper over its entire surface for ultrasonic welding either during or after its manufacturing process or printing process.

For example, additionally the desired gloss effect, moisture protection,
or the like could be accomplished during or immediately after the manufacture of the paper or before or during the printing process.

As a further pre-treatment step, a binder or water could be injected into the fold area 63 of the already stacked paper layers. The paper layer can be pre-perforated and simultaneously or subsequently applied with binder or water by means of hollow or tubular needles. It is also possible to shower the paper layers with droplets of liquid (according to the simultaneously filed patent application entitled ``Method for binding of paper layers with abrasive agents'' Swiss Patent Section 0).
1155/89-3).

As mentioned, the sonotrode 24 on the welding material 26
butt point 27 to absorb the contact pressure exerted by
is necessary. This abutment point may be anywhere on the plate as shown in FIG.

Another possibility is that the abutment point is a wrist-like device 27, on which a layer of paper is placed in the scale flow of a printing press, as shown in FIG. In this case, the abutment point may be rod-shaped or wrist-shaped.

FIG. 9 shows an exemplary printing machine setup with an integrated ultrasonic welding device for paper layers. For paper, use the paper loading device 90
to a printing mechanism 91, which may include several printing stages. The printed product is then cut lengthwise and optionally fed to a cutting mechanism 92.

The prints then proceed to a welding pretreatment means 94 where, for example, a binder is pressed or sprayed.

The printing material is then bundled and transported further. Welding pre-treatment, optionally by dosing with a binder, can be carried out on the bundled paper layers. The print then advances into an ultrasonic welder 95 where the paper layers are bonded. The bundled product is then received by removal means 96, for example as scale flow 93.

[Brief explanation of drawings]

FIG. 1 is a diagram of an ultrasonic welding device, such as is used, for example, to join brass. FIG. 2 is a diagram showing the principle of the ultrasonic transducer booster sonotrode means. FIG. 3 shows a first possible conical shape of the sonotrode tip. FIG. 4 shows a second form of the sonotrode in the form of a knife blade. FIG. 5 shows a third possible sonotrode shape as a knife blade with a notch. FIG. 6 shows a paper with a strip-like pre-treatment. FIG. 7 shows a device for ultrasonic welding of paper layers by plate-like abutment points. FIG. 8 shows the corresponding welding of the paper layers on the spine by bar-shaped abutment points. FIG. 9 is a diagram showing an example of printing machine equipment in which an ultrasonic welding device is integrated. In the figure, 11 is the main part, 12 is an amplifier, 13 is a transformer, 14 is a positive feedback means, 15 is a positive feedback key, 20 is an ultrasonic generator, 21 is an ultrasonic transducer, 22 is a piezo ceramic plate, and 23 is a passive element, 24 is a sonotrode, 25 is a tip, 26 is a welding material, 27 is an abutment point, 31 is a cone, 32 is a tip, 41 is a flat end of the sonotrode, 42 is a welding end, 53 is a cut, 61 is a paper ,
62 is a fold area, 63 and 64 are strip areas, 90 is a paper loading device, 91 is a printing mechanism, 92 is a cutting mechanism, 93 is a scale flow, 94 is a welding pre-treatment means, 95 is an ultrasonic welding device, 96 is a It is a means of removal.

Claims (1)

Claims: (1) A method for binding paper layers in the form of a booklet, binding or book or into an insert sheet, characterized in that ultrasonic binding is used. 2. Method according to claim 1, characterized in that, before the ultrasonic operation, the paper layer is subjected to a general or localized pretreatment. 3. Process according to claim 2, characterized in that the pre-treatment consists in applying a binder. 4. The method of claim 2, wherein the pretreatment comprises moistening. (5) A method according to claim 2 or claim 3, characterized in that the pre-processing is carried out before printing, such as during paper manufacturing. (6) A method according to claim 2 or claim 3, characterized in that the pre-processing is carried out during the printing process. (7) A method according to one of claims 2 to 4, characterized in that the pre-processing is performed after printing, optionally in scale flow. (8) A method according to claim 6, characterized in that the pre-treatment consists of a printing operation and the binder is included in the printing ink or the printing ink itself is a binder. (9) Method according to one of claims 5 or 7, characterized in that the pretreatment consists of a spraying operation. 10. Process according to claim 7, characterized in that the pre-treatment consists of injecting a binder or water into the paper layer. 11. Process according to claim 1, characterized in that the ultrasonic action on the paper layer is carried out in a dot-like or strip-like manner. (12) Apparatus according to claim 1 for binding layers of paper in the form of a booklet, a staple or a book, or for binding into insert pages, the binding means comprising a control means (10) and an ultrasonic generator. (20), which in turn comprises an ultrasonic transducer (21), optionally an amplitude transformer, a so-called booster (23), and a tip (32) or knife blade (42).
) tapering towards the sonotrode ends (25, 31
, 41) and a sonotrode (24) having an abutment point (27, 27'). (13) Device according to claim 12, characterized in that the ends (31, 41) of the sonotrode (24) are conical (31). (14) The ends (31, 41) of the sonotrode (24) have a knife blade shape (41) and optionally have a notch (53).
13. The device according to claim 12, characterized in that it comprises: ). (15) Device according to claim 12, characterized in that the abutment point is plate-shaped (27), rod-shaped or wrist-shaped (27'). 16. Device according to claim 12, characterized in that the ultrasonic binding device (10, 20) is integrated into the printing machine equipment. (17) Device according to claim 12, characterized in that the ultrasonic binding device (10, 20) is placed in the scale flow (93).