EP0296999A1 - Apparatus for the automatic finishing of flexible materials - Google Patents

Abstract

This finishing process comprises the following successive stages performed continuously: - application to the piece (18) and with the aid of a continuous printing machine (11, 21) of the halftone type, of a controlled small quantity of a finishing product (16) containing from 90 to 100% of photopolymerisable active material, in a proportion of 5 to 35 g/m<2> of placed product, by passing through the printing machine (11, 21> - photopolymerisation of the finishing product (16> - performing a satinising or graining operation, these various stages being repeated until the desired finish is obtained. <??>The finishing product (16) employed is a product which can be photopolymerised under ultraviolet radiation and which comprises unsaturated prepolymers, liquid monomers and photoinitiators. <??>The finishing plant comprises at least one module consisting of a continuous printing machine (11, 21), an ultraviolet radiation oven (12, 22) and a satinising and graining machine (13, 23), these various machines being arranged so as to produce a continuous conveying of the pieces (12) from one machine to another. <IMAGE>

Description

The subject of the present invention is a method and an installation for the automatic finishing of flexible materials and hides or skins, whole or precut and the use of the resulting products in the footwear, leather goods, leather goods and automotive, clothing, saddlery and other fields using leathers and flexible materials such as fabrics, nonwovens, papers, synderms, coated or not.

Currently, the finishing of leathers is carried out mainly in tanning-tanning, semi-automatically, with whole skins. This finishing is carried out in several stages consisting in spraying spraying on the skins with finishing products in solution or in dispersion in a solvent or aqueous medium and in drying the skins, generally in air convection tunnels heated to 70 °. -80 ° C, these steps being repeated until a satisfactory finishing layer is obtained.

Such a finishing technique requires very long drying, so as to completely evaporate the solvents or water used which constitute 80 to 95% of the finishing product, as well as very large drying installations.

Drying also causes some pollution, in particular by the evaporation of solvents, and significant storage of skin, since it takes around 8 days to finish a single skin.

Furthermore, patent application GB-2 031 000 is known which describes a leather covering product. This product is a photopolymerizable compound under UV consisting of 40 to 90% by weight of a prepolymer of acrylates or methacrylates and styrene and by 10 to 60% by weight of urethanes-acrylates. It does not contain 100% active ingredients but also contains nitro-cellulose and is diluted in organic solvents so that it can be applied non-continuously by spraying. Although the crosslinking takes place under UV, it is necessary to wait for the complete evaporation of the solvent, which is very time consuming and leads to significant consumption of this expensive and dangerous product.

Furthermore, it is not possible to continuously process the leather and the coating product can only be applied all at once, which considerably affects its quality.

These aforementioned finishing techniques also involve numerous manipulations of taking and taking up of skins for drying and application of the product and are therefore only conceived in tanning with whole skins or cut into strips.

Finally, the relatively heavy installations necessary for the finishing operations require the treatment of large series of skins to be profitable.

However, the current trend of the markets located downstream from the tannery-tanning, in particular in the field of the clothing and footwear industry, is towards an increasingly large variety of series, corresponding to an increasing demand for customers in new collections or reassortments. This great variety of series requires changes in color and finishing products, which are difficult to achieve quickly due to the heaviness of existing installations.

The object of the present invention is therefore to remedy these drawbacks and to design a method and a finishing installation making it possible to shorten the duration thereof in order to decrease the stocks required, to be able to respond more quickly to trends in fashion, shorten delivery times and respond to requests for restocking, as well as perform this operation automatically.

The method according to the invention should also exclude the use of solvent in the finishing product, while allowing quality finishing to be obtained.

Another object of the present invention is to design an installation allowing the treatment of flexible deformable materials, such as fabrics, nonwovens, papers, synderms (coated or not) and leathers, already precut, immediately before the manufacture of the shoe, clothing or articles intended for leather goods, furniture and automobile, among others.

This object is achieved in that the method according to the invention comprises, in combination, the following successive steps carried out continuously:
- application to the part using a continuous printing machine, of the thousand point type, of a small controlled quantity of a finishing product, comprising from 90 to 100% of photopolymerizable active material, at a rate from 5 to 35 g / m2 of product deposited by passing through the printing machine,
- light-curing of the finishing product,
- execution of a satin-finishing or graining operation,
these various steps being repeated until the desired finishing is obtained.

The use of a finishing product based on 90 to 100% of active material, and therefore practically without solvent or aqueous medium, makes it possible to eliminate the evaporation phase of traditional processes and to replace it by a simple polymerization operation. under appropriate radiation, this polymerization taking place very quickly and can therefore be carried out continuously with the other operations of application of the product and of satin-finishing or graining of the skin.

This process therefore makes it possible to eliminate all the handling of picking up and taking up the skins in the traditional process linked to the drying stages. It also eliminates the storage of skins between two operations because the skins are treated continuously.

Finally, the application of the average finishing product of a printing machine of the thousand point type, ensures the deposition on the surface of the skin of a very thin and uniform layer of this product.

According to an interesting variant of the process, the step of applying the finishing product to the part is preceded by a step of dyeing by continuous impregnation.

• Figure 1 est un schéma de l'installation selon une première forme de réalisation,
• Figure 2 est un schéma de l'installation selon une seconde forme de réalisation,
• Figure 3 est un schéma du principe de fonctionnement en direct de la machine d'impression,
• Figure 4 est un schéma du principe de fonctionnement en inverse de la machine d'impression.

Anyway, the method and the installation according to the invention will be well understood and other characteristics of these will be highlighted with the aid of the description which follows with reference to the appended schematic drawing illustrating by way of nonlimiting examples several embodiments of this installation.

• FIG. 1 is a diagram of the installation according to a first embodiment,
• FIG. 2 is a diagram of the installation according to a second embodiment,
• FIG. 3 is a diagram of the principle of direct operation of the printing machine,
• Figure 4 is a diagram of the reverse operating principle of the printing machine.

As shown in Figure 1, the finishing installation according to the invention comprises a succession of machines arranged in modules, in this case two modules, 1 and 2, one after the other.

Each of the modules 1 and 2 comprises a printing machine 11, 21, making it possible to apply the finishing product, an ultraviolet radiation oven 12, 22 making it possible to polymerize the finishing product and a satin-finishing or graining machine 13 , 23 intended to obtain the desired surface finish.

Of course the number of modules is a function of the number of layers of finishing product to be applied and can be increased or decreased compared to that indicated in the present example.

As shown in particular in FIGS. 3 and 4, each printing machine 11, 21 is a machine known as of the thousand point type.

It consists of two cylinders 14,15 with horizontal axes arranged one above the other. The upper cylinder 14 is an engraved cylinder comprising a multitude of cells 14a intended to receive the finishing product 16.

A doctor blade 17 extending parallel to the axis of the cylinder 14 in the upper part of the latter makes it possible to apply to the surface of the latter the desired quantity of finishing product 16.

A conveyor belt 19 passes between the two cylinders 14 and 15 and brings between them the piece of leather or skin 18 to be coated with the finishing layer.

The two cylinders 14, 15 can rotate in opposite directions to one another as indicated by the arrows 14b and 15b, as shown in FIG. 3, the upper cylinder 14 rotating in the opposite direction to the direction of movement 19b of the belt carrier 19.

As a result, the quantity of finishing product 16 deposited on the pieces of leather or skin 18 is linked to the size of the cells 14a of the cylinder 14 as well as to the speed of rotation of the cylinder 14.

In this case, the deposit of finishing product 16 will therefore be all the more important as the cylinder 14 will rotate faster.

The two cylinders 14, 15 can also rotate in the same direction as indicated by the arrows 20 (see fig. 4), this direction being the same as the direction of movement 19b of the conveyor belt 19.

In this case, the quantity of finishing product deposited is simply proportional to the size of the cells 14a.

It will be noted that the cylinders 14, 15 allow the application of a uniform layer 16a of finishing product on the pieces of leather or skin 18.

Finishing product 16 is a liquid comprising from 90 to 100% of active materials photopolymerizable under ultraviolet radiation. This product includes unsaturated prepolymers, and liquid monomers to which photo-initiators are added.

The prepolymers are constituted by di-or tri-functional acrylate urethanes comprising acrylic unsaturations and being in the form of liquids of low molar mass. They may also include polyesters acrylates.

The liquid monomers are chosen from the following compounds:
- N - Vinylpyrolidone
- Isobornyl acrylate
- Dioctylphthalate
- Tertiobutylcyclohexane acrylate
- Octyldecylacrylate
- Ethyltriglycol acrylate.

The photo-initiators are preferably aromatic ketones which can be combined with tertiary amines as co-initiators. Preferably a mixture of diethylethioxantone / dimethylaminobenzoate is used.

The finishing product may also include coloring materials which may consist of:
- mineral pigments, carbon black,
- organic pigments,
- metalliferous dyes.

These formulations can also contain from 0 to 5% of organic solvents, intended to regulate the viscosity of finishing product 16 and to facilitate the application thereof.

By way of nonlimiting example, mention may be made of a formulation of the finishing product in accordance with the invention.

For 100 g of colorless formulation, we have:
- Urethane-acrylate such as that sold under the name "Ebecryl 210" 55 g
- Acrylate polyester such as that marketed under the name "PE 55 F" 11g
- N- Vinylpyrolidone 11 g
- Isobornyl acrylate 11 g
- Dioctyphthalate 12 g

The photo-initiators used consist of a mixture of Diethylethioxantone / Dimethyl-aminobenzoate (DETX / DMBI) (11) dissolved in an amount of 4 to 8% by weight in the liquid monomers of N-Vinylpyrolidone.

The viscosity of the finishing product is adjusted between 0.2 and 5 pascals / seconds by means of the N-Vinylpyrolidone / Isobornyl-acrylate mixture.

If the finishing product is colored, the percentage of pigments compared to the colorless formulation is variable and depends on the desired coverage and the nature of the pigment which can be more or less absorbent of UV radiation This therefore also influences the percentage of photo-initiators integrated into the formulation.

During the passage through the ultraviolet radiation oven 12, 22, the photoinitiators cause the crosslinking of the monomers and of the pre-polymers so as to give final polymers.

It will be noted that this polymerization of the product takes place almost instantaneously.

The monomers in this case play the role of diluents of the pre-polymers but because of their reactivity, they are integrated into the film of polymers occurring and there is therefore no evaporation of product apart from that of 0 to 5% of organic solvents possibly contained in the finishing product.

It is therefore clear that in this case, no more drying operation is therefore necessary and that at the outlet of the first oven 12 a second layer of finishing product can be immediately applied in the second module 2 of the installation. The ultra-violet radiation ovens 12, 22 are conventional type ovens.

They each include a conveyor 25 made of stainless material passing through this furnace right through.

These conveyors are surmounted in a manner known per se of focusing lamps (not shown in the drawing) and emitting ultra-violet radiation of frequency between 150 and 700 mm.

Following each furnace 12, 22 is placed a satin-finishing or graining machine 13, 23 the purpose of which is either to increase the gloss of the finishing layer (this is the satin-finishing operation), or to print on this finishing layer a determined relief (graining operation). Each of these machines is made up of two cylinders, the upper one called working 26 and the lower entry 27, and horizontal axes 26a and 27a respectively. The working cylinder 26 is heated to between 60 and 160 ° C and presses on the parts 18 with an adjustable pressure.

These are brought by an endless conveyor belt 28 which passes through the machine and passes between the two cylinders 26,27.

The working cylinder 26 has a smooth surface in the case where it is desired to carry out a satin-finishing operation and has a grained surface to carry out a graining operation.

The satin-finishing or graining machine is designed so as to allow an easy change of the cylinder 26. As shown in fig.1, the cylinders 26 and 27 rotate in opposite directions (arrows 26b and 27b), the working cylinder rotating in the same direction as the conveyor belt 28 (arrow 28b).

As will be easily understood, the finishing installation according to the invention makes it possible to obtain, by means of a single passage in the various modules 1 and 2 thereof, the desired finishing layer and without the need to subsequent drying. In the case of full grain leather, the deposit per pass is approximately 10 to 15 g / m2 and the speed of passage is between 5 to 10 meters / minute.

It should be noted that the finishing layer applied, although generally colored, may also be colorless.

The number of finishing coats applied depends of course on the desired finishing appearance.

However, with a printing machine allowing, by passing at a speed of about 10 m / min, a deposit of between 10 and 25 g / m2, this number of layers should not exceed three, to obtain a uniform dry film , so that for practical reasons, the pieces leathers do not become rigid and are easy to handle and stack.

It will also be noted that the viscosity of the pigmented formulation is between 0.2 and 5 pascals-seconds.

Finally, the leathers obtained, in the form of parts precut by the present process, must by way of illustration, meet the following characteristics:
- good resistance to the BALLY flexometer: no visible cracking, no peeling of the film after:
. 20,000 bends in wet
. 100,000 dry bends.
- good resistance to VESLIC friction: no or little disgorgement on the felt and no elimination of the film by peeling after:
. 100 back and forth wet
. 200 comes and goes dry.

Obtaining these two essential characteristics should not be to the detriment of the appearance: uniformity of gloss and coverage and smooth, dry feel.

Figure 2 shows another embodiment of the invention in which the installation also consists of two modules 101, 102 which are arranged here not in line, but parallel to each other.

In this installation, as in the installation previously described, each module 101, 102 consists respectively of a printing machine 111, 121, an oven 115 and a satin-finishing or graining machine 113, 123 The only difference compared to the installation of FIG. 1 is that the oven 115 extends at the same time on the two modules 101 and 102, the other machines 111, 113, 121, 123 being identical to the machines 11, 13, 21 and 23 described above.

This arrangement makes it possible to have only one oven 115 for two successive modules and is therefore particularly advantageous.

In this case, the satin-finishing or graining machine 113 of the first module 101 is connected to the printing machine 121 of the second module 102 by a conveyor 130 in the form of a semicircle capable of causing the outgoing parts to turn around. from the first module and entering the second module.

Of course, the different conveyor belts 19, 25 and 28 different machines of each module are designed so as to carry out a continuous transport of each piece of leather or skin 18 to be treated from the entry of the installation to the exit of the latter.

In addition, a regulation or coupling system between these different belts can be provided so as to convey the pieces at the same speed.

It will be noted that this arrangement makes it possible to have a fully automatic supply and evacuation of the installation.

In accordance with an advantageous variant of the invention, the finishing installation comprises a conventional impregnation dyeing station not shown in the drawing and arranged and continuous before the continuous printing machine (11,111) located at the head of the installation .

This arrangement makes it possible to complete the installation and to produce finished flexible materials which moreover have a stable and quality coloring.

In the case of a lightly touched leather, that is to say, sanded and impregnated conventionally in the dyeing station, two to three applications of a finishing layer with crosslinking after each pass are necessary. The deposit of finishing product per pass is of the order of 20 to 25 g / m2.

The installation according to the invention is particularly suitable for the treatment of flexible materials and in particular of skins already cut since it does not involve any manipulation thereof. It can, of course, also be applied to whole parts.

The installation according to the invention is therefore particularly suitable for the treatment of flexible materials and in particular leather pieces within the same shoe manufacturing company or the like and it therefore allows rapid adaptation to variable market trends.

Of course; in this case, systems will be provided to allow rapid cleaning of the printing machines as well as a rapid change of the finishing product used.

If necessary, a suction or vacuum system can be provided at each conveyor belt to hold the parts.

If necessary also, a doctor blade type system can be provided at the level of the printing and satin-brushing rollers in order to prevent the adhesion to the treated parts.

It goes without saying that the present invention is not limited to the sole examples of embodiments, but on the contrary encompasses all of the embodiments thereof.

Claims (15)

1- Automatic finishing process for flexible materials and in particular for parts (18) of hides or skins, characterized in that it consists of the combination of the following successive steps carried out continuously:
- Application to the part (18) using a continuous printing machine (11, 21, 111, 121) of the thousand point type, of a small controlled quantity of a finishing product (16) comprising 90 to 100% of light-curing active material, at a rate of 5 to 35 g / m2 of applied product, by passage through the printing machine (11, 21, 111, 121).
- Light-curing of the finishing product (16),
- Execution of a satin-finishing or graining operation, these different steps being repeated until the desired finish is obtained. 2- The finishing method according to claim 1, characterized in that the step of applying the finishing product (16) on the part (18) is preceded by a dyeing step by continuous impregnation. 3- A finishing process according to claim 1 or claim 2, characterized in that the finishing product (16) used is a product photopolymerizable under ultraviolet radiation. 4- The finishing process according to claim 3, characterized in that the finishing product (16) comprises unsaturated pre-polymers, liquid monomers as well as photo-initiators. 5- Finishing process according to claim 4, characterized in that the unsaturated prepolymers are chosen from urethane acrylates and / or polyesters acrylates. 6- Finishing process according to claim 4, characterized in that the liquid monomers are chosen from the following compounds:
- N- Vinylpyrolidone
- Isobornyl acrylate
- Dioctylphthalate
- Tertiobutylcyclohexane acrylate
- Octyldecyl acrylate
- Ethyltriglycol acrylate. 7- Finishing process according to claim 4, characterized in that the photo-initiators are chosen from mixtures of diethylthioxantone / Dimethylaminobenzoate. 8- finishing process according to any one of claims 1 to 7, characterized in that the number of finishing layers applied is limited to three in the case of a quantity of finishing product deposited between 10 and 25 g / m2 per passage to the printing machine. 9- Finishing process according to any one of claims 1 to 8, characterized in that the viscosity of the finishing product is between 0.2 and 5 pascals / second. 10- Finishing installation for implementing the method according to any one of claims 1 to 9, characterized in that it comprises at least one module constituted by a continuous printing machine (11, 21, 111, 121), an oven with ultraviolet radiation (12, 22, 115) and a satin-finishing and graining machine (13, 23, 113, 123), these different machines being arranged so as to carry out a continuous transport of the parts ( 12) from one machine to another. 11- Finishing installation according to claim 10, characterized in that it further comprises a dyeing station by impregnation arranged continuously before the printing machine (11, 111). 12- Finishing installation according to claim 10 or claim 11, characterized in that the continuous printing machine (11, 21, 111, 121) is a thousand point type machine. 13- Finishing installation according to claim 12, characterized in that the continuous printing machine is constituted by 2 cylinders (14, 15) of horizontal axes and a conveyor belt (19) passing between the two cylinders and bringing between them the part (18) to be worked. 14- Finishing installation according to any one of claims 10 to 13, characterized in that the installation consists of two modules (101, 102) arranged parallel to each other and in that a conveyor ( 130) in the form of a semicircle connects the satin-finishing or graining machine (113) of the first module (101) to the printing machine (121) of the second module. 15- Finishing installation according to claim 14, characterized in that it comprises a single oven (115) with ultraviolet radiation extending at the same time on the two modules (101 and 102).

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