EP0855146A1 - Method for making a fusible interlining and interlining obtained thereby - Google Patents

Abstract

The production of heat-adhesive cloth (I) comprises placing spots of thermofusible polymers (II) of average thickness E on the front of (I) and subjecting them to electron bombardment (III). (II) contains radical primers but no photo-inhibitor, and the depth of penetration of the electrons is regulated in such a manner as to alter the physical and chemical properties of (II), e.g. m. pt., viscosity, etc., to a depth e.

Description

The present invention relates to the field of fusible linings which are supports, textile or non-woven, on one side of which are applied points of hot-melt polymer, likely to adhere later on the piece of clothing to be reinforced under the effect of the application of a certain hot pressure. It concerns more particularly a process for manufacturing such a covering, is carrying out an electronic bombardment in order to locally modify the melting point and / or viscosity of the hot-melt polymer; she also relates to a fusible interlining obtained by said process whose hot melt polymer dots have a melting temperature or their viscosity differentiated in their thickness.

Among all the problems encountered in the field of interlining one of the most difficult to solve is the risk of piercing of the interlining support during application by pressure to hot of the fusible interfacing against the piece of clothing to be reinforced. Indeed the temperature which is chosen to carry out this application at hot must allow the polymer point to be melted so that so that the polymer thus melted can distribute and adhere to the fibers or filaments on the surface of the piece of clothing. It happens however frequently this distribution is not only made on the surface but that the polymer flows through the fibers or filaments and appears on the opposite surface of the interlining support. This does not affect the aesthetically, unless the interlining is intended to be visible and to form the back side of the garment. In any event, this piercing has for effect of locally increasing the stiffness of the interlining and therefore of the part of clothing, which may be contrary to the desired effect. cause bonding on lining fabrics such as lining and lapels of drapery, which causes degradation of the quality of the garment.

To resolve this difficulty, it has already been proposed to carry out a fusible interlining with hot melt polymer points have two superimposed layers, namely a first layer in contact with the right side of the stabilizer support and a second layer arranged precisely above the first. Course constituents of the two layers are determined so that when hot press application of the piece of clothing, only the second layer hot melt polymer reacts to the action of temperature. The diffusion of the hot-melt polymer may in this case not to be done only towards the piece of clothing, being prevented towards the support interlining, the first layer acting as a kind of barrier.

In practice this double layer technique presents disadvantages, in particular difficulty in achieving the superposition of two layers and risk of delamination of the two layers.

To overcome these drawbacks, the applicant has already proposed, in the document FR 2 606 603 to implement means of a nature chemical, acting on the hot-melt polymer in order to modify its chemical structure, at least partially, at least at the interface with the interlining support, so as to prevent the hot-melt polymer from stick through the interlining under the effect of heat and / or pressure and / or steam. The means, chemical in nature, suitable for modify the chemical structure of the hot-melt polymer at least one reactive material and at least one reactive means capable of initiating, ensure, promote the reaction between the reactive material and the polymer hot melt.

Are explicitly mentioned different categories of materials reagents, namely aminoplast thermosetting products, in particular urea formaldehyde and melamine formaldehyde, single molecules or polymers bearing at least one isocyanate function blocked or not, simple molecules or polymers carrying at least one aziridine function, modified polymers carrying at least one reactive chemical function, in particular epoxy function or vinyl function.

Among the reactive means, the heat inputs, the ultraviolet radiation, electronic bombardment. It is stipulated that this reactive means can be used in the presence of catalysts. More precisely when the reactive means of the crosslinking reaction of the hot melt polymer and modified vinyl reactive polymer is UV radiation, it is expected that this will occur with contact of photo-initiator products.

With particular regard to electronic bombardment as a reactive medium, provision is made to add to the polymer mixture hot melt and reactive material a photo-inhibitor to mimic propagation of the chemical modification reaction. We pass the interlining support coated with the mixture in front of a photonic source or electronic located on the side of the uncoated side of the support so that the particles preferentially bombard the holes or perforations of the support, opposite the hot-melt polymer.

In practice, it has proved impossible to obtain, under the conditions described in document FR 2 606 603, satisfactory results in using electronic bombardment as a reactive means, despite everything the value of this technique. Difficulty controlling, using photoinhibitors, the spread of the chemical reaction and the difficulty in acting preferentially at the holes or perforations of the interlining support, facing the hot-melt polymer, are among the reasons for this failure.

The goal set by the applicant is to propose a method of manufacture of a fusible interlining using a electron bombardment to modify the chemical structure of the polymer hot-melt which overcomes the aforementioned difficulties.

In a known manner, according to this method, is deposited on the face location of a stabilizer support, chosen from textile supports and non-woven, dots of hot melt polymers of medium thickness E and one of the faces of said support is subjected to bombardment electronic.

Characteristically according to the invention, the points of hot-melt polymers, containing a radical activator and being free of photo-inhibitor, the depth of penetration of the electrons in the points of the hot-melt polymer is adjusted to obtain a modification of the physico-chemical properties of the hot-melt polymer, chosen from the melting temperature and the viscosity, over a thickness e with respect to the average thickness E.

The function of the radical activator is to create free radicals allowing to initiate the polymerization reaction on itself of the polymer hot melt. It is akin to the photo-initiating agent provided for in the document FR 2 606 603 during the implementation of UV irradiation as a reactive medium. The radical activator is therefore not properly speak of a reactive substance in the sense provided for in document FR 2 606 603.

Preferably, this radical activator is of the acrylic type, in particular trimethylol propane trimethacrylate or trimethylol propane triacrylate. These two compounds are acrylic-functional monomers and are not part of the explicitly provided list, for the subject reactive, in document FR 2 606 603.

Thanks to the radical activator and the absence of photo-inhibitor, it is possible to obtain a structural modification of the hot-melt polymer over a limited thickness e of each point of the fusible interlining.

In a first alternative embodiment, the reverse side of the interlining support is subjected to electronic bombardment and the penetration depth of the electrons is adjusted to obtain the modification of the physicochemical properties over a thickness e of between 10 and 50% of l 'average thickness E , the modification consisting in an increase in the melting temperature or in an increase in the viscosity of the hot-melt polymer.

In a second alternative embodiment, the face side of the interlining support is subjected to electronic bombardment and the depth of penetration of the electrons is adjusted to obtain a modification of physicochemical properties over a limited thickness of between 50 and 90% of l 'average thickness E , the modification consisting in a decrease in the melting temperature or a decrease in the viscosity of the hot-melt polymer.

In any case, each point of polymer happens to be made by a single deposit, monolayer, and after the bombardment action electronic, said layer has a melting temperature and / or a differentiated viscosity between a first lower zone which is in contact with the textile support and which has a melting temperature and / or a given viscosity and a second upper zone which has a temperature of melt or a viscosity lower than that of the hot-melt polymer of the first zone.

When applying fusible interfacing against the workpiece of clothing, by hot pressing, it is the second zone which is in contact with the piece of clothing and which presents the melting temperature the weaker that will react the most to the action of heat, while the first zone that has a higher melting temperature does not react or to a lesser extent. Therefore this first zone is used in some kind of barrier to creep of the hot melt polymer of the second zone.

Whatever the variant, there is a modification of the melting temperature and / or viscosity which is gradual in the thickness of the point. As a result, there is no risk of cohesion or delamination between two layers of different densities, as is the case during the implementation of the double layer technique, according to which each point consists of two layers of different hardnesses always having a preferential breaking point between the layers.

It should be noted that the electron beam generated by the cannons at industrial electrons does not have a uniform action in the thickness of a given material. As the electron beam enters inside the material, the quantity of electrons or dose decreases as and thickness measurement, until it becomes zero at a given thickness, which is a function of the acceleration voltage of the electron beam. By example for an electron gun whose acceleration voltage is 150 kV, we consider that the electron dose is canceled for a thickness of 200 µm, through a material of density 1. This dose is still around 50%, in this case, for a thickness of around 130 µm.

The applicant has found that in order to obtain a modification of the physicochemical properties of the hot-melt polymer which is such that the lower layer of the point can play the desired barrier effect, avoiding the piercing of the fusible interlining, it was necessary for it there is a certain dose of electrons which has reached the radical activator. The adjustment of the depth of penetration of the electrons, as provided by the process of the invention, therefore aims to ensure that there is this sufficient dose of electrons which could have penetrated into the limited thickness e of the hot-melt polymer, that is to say the thickness for which the modification of physicochemical properties is sought.

Since industrial electron guns are standardized and it is not easy to vary the voltage acceleration, according to the method of the invention, the depth of penetration of the electron beam into the polymer points hot melt by interposing a filter between the electron beam and the stabilizer support.

This filter has the effect of artificially reducing the thickness of penetration of the electron beam into the hot-melt polymer and therefore to precisely adjust the really effective penetration depth.

The choice of filter, which can in particular be a sheet of paper and, in particular its thickness, depends on the material constituting the stabilizing support and on the thickness e for which a modification of the physicochemical properties is desired.

For example, for an electron gun with an acceleration voltage of 150 kV, a paper filter weighing on the order of 50 to 60 g / m ² has been interposed.

Preferably the operating conditions of the bombardment electronics as well as the choice and quantity of radical activator are determined so that the melting point of the polymer hot-melt has a variation, more or less of the order of 1O to 20 ° C in the area subject to electronic bombardment.

• La figure 1 est une représentation schématique en plan et fortement grosse d'un entoilage thermocollant,
• et la figure 2 est une représentation schématique en coupe dudit entoilage au droit d'un point de polymère.

The present invention will be better understood on reading the description which will be given of two exemplary embodiments of a fusible interlining whose points of hot-melt polymer, monolayer, have a different melting temperature, illustrated by the appended drawing in which:

• FIG. 1 is a schematic plan view and very large of a fusible interlining,
• and Figure 2 is a schematic sectional representation of said interlining in line with a polymer point.

A fusible interlining 1 consists of a support 2 and points 3 of thermofusible and fusible polymer. The support can be either a textile support proper, of the woven, knitted or knitted type weft insertion, a nonwoven. 3 points of polymer hot-melt are arranged on all or part of the surface of one of the two faces of the support 2, called the face side. It is this face that is intended to be applied against the reverse side of the piece of clothing to protect or strengthen.

The hot-melt polymer is a known type, among polyamides, polyethylenes, polyurethanes, polyesters, aminoplasts ... This can also be a copolymer. The important thing is that the polymer in question can, at the temperature of application of the piece of clothing under hot pressure, react by locally melting to adhere to the fibers or filaments on the reverse side of the piece of clothing.

Conventionally, the polymer dots are deposited in the form of an aqueous dispersion which is then subjected to a heat treatment so as to evaporate the solvent and agglomerate new hot melt polymer particles to achieve their hanging on the support. The polymer points are deposited by any conventional technique, in particular printing with a rotary frame or other.

In practice, the polymer points on the surface of the interlining support represent of the order of 5 to 20 g / m ² , depending on the type of support.

The aqueous dispersion of hot-melt polymer comprises also a radical activator, i.e. a compound which is capable of form free radicals under the effect of electronic bombardment, and is free of photo-inhibiting agent.

It is for example, but not exclusively, an activator of the acrylic type, such as trimethylol propane trimethacrylate or else trimethylol propane triacrylate.The proportion of radical activator can be between 5 and 20% by weight relative to the hot-melt polymer.

In a first exemplary embodiment, after having carried out the deposition of the aqueous dispersion of hot-melt polymer and then the heat treatment of the latter in order to evaporate the water contained in the dispersion and to agglomerate the mixture of hot-melt polymer and activator, electron bombardment is carried out on the reverse side 2 b of the interlining support 2, that is to say the face which does not include the points 3 of polymer. The electrons pass through the filaments or fibers 4 of the support 2 and penetrate into the point of polymer 3 where they meet the radical activator. Under the effect of these electrons, the radical activator generates free radicals which develop crosslinking reactions in zone 3 a of the hot-melt polymer.

In this variant embodiment, the penetration depth of the electrons, the quantity and the choice of the radical activator are determined so that only zone 3 a of the hot-melt polymer which is in contact or in the immediate vicinity of the fibers or filaments 4 of the support and subjected to the action of the electrons undergoes the desired modification of the physicochemical properties, namely an increase in the melting temperature or in the viscosity of the hot-melt polymer. In FIG. 2 is shown schematically the separation of this first zone 3 a , with modified structure, from the second zone 3 b with unmodified structure by a broken line 5. In reality the action is gradual in thickness point. Anyway, it is created, under the controlled action of electronic bombardment, a differentiation in the thickness of each point of polymer 3. This differentiation due to a certain crosslinking, results in this first example by an increase of the melting temperature of the hot melt polymer constituting the first zone 3 a , this melting temperature remaining unchanged with regard to the second zone 3 b not significantly modified by the action of the electrons.

It should be noted that each point of hot-melt polymer, in which penetrate the electrons, constitutes a solid medium. Therefore, the cross-linking reactions, generated by free radicals, do not propagate only very weakly, unlike what might happen if it was a liquid medium.

When the hot-pressing interlining 1 is applied under hot pressure to the item of clothing, at the temperature usually used for the hot-melt polymer in question, only the second zone 3b of each point 3 is brought to react, that is to say to exercise its adhesive power by melting the hot-melt polymer. The application temperature is insufficient, due to the increase in its melting temperature, to react the polymer contained in the first zone 3 a . Thus during the application under pressure, the polymer of the second zone 3 b cannot creep through the wires or filaments 4 of the support 2, this creep being prevented by the first zone 3 a at point 3, which does not react and acts as a barrier.

So that this barrier effect can be effective while not unduly reducing the adherent action of each point 3, the operating conditions, and in particular the penetration depth of the electrons, are determined so that the relative thickness of the first zone 3 has to be between 1O and 5O% of the total thickness from the point of polymer 3, preferably between 10 and 20%.

Polyamides or high density polyethylenes or polyurethanes have been used as hot melt polymers and as radical activators trimethylol propane trimethacrylate or trimethylol propane triacrylate in an amount of 5 to 20% by weight of polymer. The hot melt polymer deposition was carried out at a rate of 9 to 16 g / m ² on the interlining support. An electron gun was used, with doses between 10 and 75 KGy and acceleration voltages from 100 to 200 kV. The electron penetration depth is adjusted by interposing paper filters weighing between 50 and 100 g / m ² .

The best results have been obtained with a mixture of high density polyethylene, as hot-melt polymer, and trimethylol propane trimethacrylate, as free radical activator, the latter being present in the order of 20% by weight relative to the hot-melt polymer, in the case where the mixing of these two components is carried out initially in the aqueous dispersion used for the deposition of polymer dots. These best results were obtained by using a dose of electrons of 50 kGy and a filter of 56 g / m ² . The bonding tests showed a significant increase in the bonding forces, under the same conditions and at the same temperature, compared to a control sample which had not undergone electronic bombardment. In addition, crossing tests were carried out in which a sample of interlining was folded back on itself so as to apply two reverse sides against each other, not carrying a point of hot-melt polymer and the force was measured. necessary to separate these two faces after applying pressure at a temperature between 150 and 170 ° C. These tests showed a virtual disappearance of the separation forces, significant from the crossing of the hot-melt polymer through the interlining support, for the samples subjected to electron bombardment. On the other hand these forces of separation remained important for the control sample, not subjected to the electronic bombardment; they were, for an application temperature of 150 ° C., of the order of 25 to 30% of the bonding forces, that is to say the forces necessary to separate the right side of the sample applied to an article of reference.

It would be possible to decrease the relative amount of activator radical with respect to the hot-melt polymer by carrying out a preliminary mixing operation intended to have a more intimate contact between the radical activator and the hot-melt polymer. For that we mix the hot-melt polymer and the radical activator, in the form of powders, this mixture is subjected to successive operations of fusion, extrusion and grinding so as to obtain a powder which is then put in aqueous dispersion to form the paste used for the deposition of hot-melt polymer on the right side of the stabilizer support.

It should also be noted that this effect of increasing the temperature of the hot-melt polymer can also be obtained by adding a curable filler to the polymer dispersion, i.e. a charge which under the action of electronic bombardment will polymerize and harden irreversibly, thus no longer being reactivated thermally as is the case with the hot-melt polymer. The acrylic monomers are part of the curable fillers. So if he is itself of the acrylic type, the radical activator can also constitute partly a curable filler.

In another embodiment, the electron bombardment takes place on the two facing support 2.The operating conditions of the electron bombardment, the thermofusible polymers, and the activators are selected so to have the opposite effect to that of the first example, namely a decrease in the melting temperature and / or the viscosity of the polymers under the action of electron bombardment. With this difference, the considerations given above remain valid.

In this case, we start from a copolymer having a temperature of fusion of 140 ° C. to bring it into the zone subjected to EB radiation, at a temperature of 100/120 ° C.

Claims (11)

Process for manufacturing a fusible interlining according to which a stabilizing support (2), chosen from text supports and nonwovens, is deposited on the face side (2 a ) of points (3) of hot-melt polymer of average thickness E and one of the faces (2 a , 2 b ) of the support (2) is subjected to electronic bombardment, characterized in that the points (3) of hot-melt polymer containing a radical activator and being free of photo-inhibitor, the depth of penetration of the electrons in the points (3) of hot-melt polymer is adjusted to obtain a modification of the physicochemical properties of the hot-melt polymer, chosen from the melting temperature and the viscosity, over a limited thickness e with respect to the average thickness E. Method according to claim 1, characterized in that the reverse side (2 b ) of the interlining support (2) is subjected to electronic bombardment, in that the limited thickness e is between 10 and 50%, preferably 10 to 20%, of the average thickness E and in that the modification of the physicochemical properties of the hot-melt polymer consists in an increase in the melting point of said polymer. Method according to claim 1, characterized in that the face side (2 a ) of the interlining support (2) is subjected to electronic bombardment, in that the limited thickness e is between 50 and 90% of the thickness average E , preferably 80 to 90%, and in that the modification of the physicochemical properties consists in a reduction in the melting point of said polymer. Method according to one of claims 1 to 3, characterized in that, decreases the penetration depth of electrons by interposing a filter on the path of the electron beam. Method according to claim 4, characterized in that the tension electron beam acceleration is at least 100kV and in that a filter is interposed on the path of the corresponding electron beam a reduction in the penetration depth between 50 and 100 µm. Method according to one of claims 4 or 5, characterized in that a paper having a grammage of between 50 and 100 g / m ² is used as a filter. Method according to claim 1, characterized in that the activator radical is a monomer of the acrylic type, chosen in particular from trimethylol propane trimethacrylate and trimethylol propane triacrylate. Process according to claim 7, characterized in that the polymer hot melt is a high density polyethylene, in that the activator radical is trimethylol propane trimethacrylate in an amount of 5 to 20% by weight compared to high density polyethylene. Method according to claim 1, characterized in that for the preparation of the aqueous dispersion in the form of a paste containing the hot-melt polymer and radical activator and used for the deposition of polymer points on the right side of the stabilizer support, we realize before mixing the hot melt polymer and the activator radical in the form of powders, this mixture is subjected to operations successive melting, extrusion and grinding so as to obtain a powder which is diluted to obtain said aqueous dispersion. Method according to claim 1, characterized in that the variation of melting temperature in the area subject to electronic bombardment is of the order of 10 to 20 ° C. Method according to claim 1, characterized in that the points of hot melt polymer additionally contain a curable polymer, under the action of electronic bombardment or radical activator.

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