EP0636728A1 - Process for manufacturing a glass mat with filaments - Google Patents

Abstract

The invention relates to a process for manufacturing mats of continuous glass yarns, at least part of the said yarns being coated with a non-aqueous mixture capable of reacting under actinic radiation. The mats obtained have sufficient homogeneous cohesion throughout their thickness, this cohesion being important for obtaining composites having good mechanical properties using the said mats.

Description

The present invention relates to a method for manufacturing glass mats with continuous wires, at least part of said wires being coated with a mixture in the liquid state capable of reacting under actinic radiation.

It is already known to stretch from the orifices of one or more dies glass filaments in the form of continuous filaments which are coated with a size intended in particular to protect their surface and which are then gathered into wires , said strands then being projected towards a collecting surface moving transversely to the direction of the projected strands in order to form a sheet of intermingled or "matt" continuous strands, the strands in question possibly also being coated with a binder capable of ensuring their cohesion within the mat after passing through an oven. Such a process is illustrated in particular in patent FR 1 379 770 in which the binder used consists of powders or emulsions, the size being essentially aqueous.

Due to the humidity deposited within the threads, in particular by the size, it is necessary to provide efficient and therefore costly drying means, water being able to harm the good adhesion of glass to matrix in the subsequent manufacture of composite products.

For reasons of convenience, the drying can be carried out at the level of the oven ensuring the hardening of the binder; it is then necessary to provide for a further steaming of the mats. Such treatment, however, requires additional energy consumption, involves the use of relatively heavy equipment and limits productivity. It is, moreover, difficult to carry out a homogeneous drying of the mats in the case of drying by steaming, the removal of the humidity in the absence of air circulation within the mat being difficult to do in the lower layers of the mast. As a result, the mat obtained is not homogeneous; it also does not have sufficient cohesion throughout its thickness, and in particular at the level of the lower layers.

In order to improve said cohesion of the mat, it is known to subject the mat in question to the action of needles making it possible to entangle the constituent wires of the mat. Such a needling process is described in US Pat. No. 3,883,333 concerning mats produced from filaments coated with an aqueous composition. However, the needling device used in this process does not overcome the problems associated with drying the mat, the size used being essentially aqueous.

The object of the invention is therefore to establish a process which does not have the above-mentioned drawbacks, this process being mainly more economical and rapid and also making it possible to obtain mats having a homogeneous and sufficient cohesion throughout their thickness. , this cohesion being important for obtaining using said mats of composites having good mechanical properties.

This object is achieved by a method of manufacturing a mat formed by a sheet of continuous glass wires emanating from one or more dies, according to which a multiplicity of melted glass fillets is drawn from the orifices of each die. in the form of sheets of continuous filaments, the filaments are collected in at least one wire, each wire being mechanically driven by a drawing system provided with a member ensuring the projection and distribution of said wire on a collecting surface or a conveyor in transverse movement relative to the direction of the projected threads, the filaments being coated with a non-aqueous size capable of reacting under the action of actinic radiation and the glass threads being subjected, after distribution on the conveyor, to the action of one or more actinic radiations.

Note that the expression "non-aqueous size" according to the invention designates a size composition comprising less than 10% of water, the presence of water may be necessary in certain cases, in particular in acrylic compositions to facilitate the hydrolysis of silanes.

This process has many advantages compared to traditional aqueous methods, advantages which will be highlighted during the following description.

According to the present invention, the filaments formed by drawing streams of molten glass from the orifices of one or more dies are coated using a sizing device with a non-aqueous size. The fact of using a nonaqueous sizing eliminates the need to resort to a parboiling of the mats and therefore makes it possible, first of all, to save energy while increasing productivity. But above all, it turns out that the use of non-aqueous size capable of reacting under actinic radiation makes it possible to obtain yarns with particularly advantageous characteristics for the formation of mats having good cohesion.

Indeed, mainly due to the nature of the size used according to the invention and also due to the use of this size in lesser quantities by volume compared to those of an aqueous size taken under the same conditions, better wetting of the filaments and sheathing of each filament by capillary action are observed, which favors the sliding of the filaments relative to one another within the same thread. As a result, the wires, after their contact with the surface of the drawing device, have a more flattened shape than those obtained when using aqueous sizing and, consequently, at the level of the mat, greater recovery capacity. The cohesion of the threads within the mast is thus improved.

The sizes used can be, in particular, sizes crosslinkable under the action of ultraviolet radiation or sizes crosslinkable under the action of infrared radiation. Preferably, the nonaqueous sizes used are sizes capable of reacting under the action of ultraviolet radiation. The rate of photoinitiators within such sizes is, moreover, preferably between 2 and 5% according to the invention. Examples of size according to the invention are given later in Examples 1 and 2.

It should also be noted that the actinic treatment of the wires according to the invention being carried out on the sheet of glass wires on the collecting surface in motion and, consequently, at speeds of displacement of the wires much lower than the drawing speeds, it it is therefore not necessary to have recourse to particularly reactive and therefore costly sizes. Note also that it is possible to use a sizing alone, the sizing also playing in this case the role usually reserved for the binder. This nevertheless requires the use of a large amount of size, which can make the process prohibitive in terms of cost, and may lead after polymerization to son having too high rigidity within the mat. It is therefore desirable to separate and deposit the size and the binder separately, each having a very specific function. The size, in fact, ensures in particular the protection of the threads against abrasion, while giving them the properties essential for subsequent transformations, the choice of size being determined according to the physical properties of the composite that is desired later. get while the binder keeps them wires within the mast by creating bonding or bonding surfaces at the crossing or contact points of the wires.

The deposit of size and the deposit of binder according to the invention are therefore preferably carried out in separate operations.

In particular, the binder is preferably deposited on the moving mat before the mat is subjected to actinic radiation. The binder is also non-aqueous for the same reasons as those previously mentioned for the sizing. This binder can be in different forms. In particular, it may be a binder reacting under the action of infrared radiation or a binder reacting under the action of ultraviolet radiation. Use is preferably made of a binder capable of reacting under infrared radiation, such as a polyester, and which is in the form of a thermoplastic or thermosetting powder making it possible to create an effective point bonding of the wires. Unless there is a large selection of the components of the size and of the binder, the photocrosslinkable liquid binders have the disadvantage of being generally of a fairly similar nature with the sizes used. The pulverized binders then tend to be distributed along the fibers by affinity with the size deposited under die, instead of remaining in the form of droplets making it possible to create points of contact. Furthermore, whatever the binder, the binder pressure and the spraying parameters, the liquid binder tends to concentrate in the upper layers of the mats. As liquid binder, it is nevertheless possible to use in particular mixtures based on polyurethane acrylate and N-vinylpyrrolidone in the presence of a photoinitiator.

Just as the use of non-aqueous photocrosslinkable size allows the production of yarns with particular characteristics, the use of size and non-aqueous binder according to the invention allows the production of mats having certain characteristics.

It should, in fact, be pointed out that if the threads coated with the size according to the invention are flatter, the mat obtained is on the other hand more swelling, no longer having to undergo the weight of the water coming from the different finishes (an aqueous size indeed contains at least 90% by weight of water and gives a mat having a water content of at least 20%). The swelling of the mat results in a reduced number of contact points between the wires and a significant thickness. Only the weight of the binder can, by gravity, force the appearance of contact points between wires, which requires the use of large quantities of binder to bind the lower layers. According to the invention, the mat is therefore preferably calendered and / or is the subject of a needling before irradiation so as to force the points of contact between wires and remove the initial bulking. Yes the binder is in powder form, calendering and / or needling can take place before and / or after depositing the binder, calendering and needling after depositing the binder has the advantage of facilitating the distribution of the powder in the thickness of the mat. However, in the case of calendering, calendering preferably takes place before spraying the binder if the latter is in liquid form, in order to avoid having a sticky mat adhering to the calendering roller.

However, it should be noted that, since the liquid binder tends to concentrate in the upper layers of the mats, as seen above, obtaining a homogeneous mat means using a large quantity of binder so as to make it penetrate by gravity to the layers lower, which can lead to the manufacture of a semi-composite that is difficult to handle. It is therefore desirable, in the case where a photocrosslinkable liquid binder is used, to perform a needling of the mat rather than a calendering or, optionally, to choose a binder so that it is immiscible with sizing to avoid problems of distribution by affinity as seen above. Needling occurs, preferably, after spraying the binder, when the binder used is liquid, to promote the creation of contact points.

Note, moreover, that calendering, needling and binder deposition preferably take place before irradiation, the threads becoming elastic in the opposite case and therefore retaining their initial shape whatever the intensity of calendering or needling. and the weight of binder sprayed.

Depending on the embodiment of the present invention, one or more irradiation devices may be necessary. Thus, in the case where the size and the binder deposited are both crosslinkable under infrared radiation, a single irradiation device is necessary for the treatment of the mats. The duration of the heating intended for the modification of the state of the binder is then very reduced due to the absence of water to be discharged.

Also, in the case where the size and the binder deposited are both crosslinkable under ultraviolet radiation, a single irradiation device is necessary.

In the case of a crosslinkable size and binder, one under ultraviolet radiation, the other under infrared radiation, it is then necessary to provide an infrared oven as well as an ultraviolet irradiation device. The presence of these two devices does not slow down the speed of manufacture of the mats, the exposure time within the heating device remaining particularly short due to the absence of water to be evaporated. and the exposure time within the irradiation device depending on the speed of the conveyor and the intensity of the radiation emitted by the irradiation device.

According to one embodiment of the invention, it is also possible to subject the mat to a first deposit of binder at the level of the first dies followed by a first irradiation, then to a second deposit of binder at the level of the last dies before irradiation final, each of these deposits being preceded and / or followed by calendering and / or needling according to what has been seen previously. This process notably facilitates the impregnation of the layer of wires by the binder, whether this is of liquid or powder nature. However, it requires at least two binder spraying devices and, optionally, two calendering and / or needling devices.

Other advantages and characteristics of the invention will be highlighted in the following description with reference to the drawing illustrating a preferred embodiment of the invention.

It is useful to note that this embodiment of the invention is illustrative and not limiting.

The figure shows a schematic front view of an installation allowing the implementation of the method according to the invention.

According to this figure, strands of molten glass are drawn from dies 10 in the form of sheets of continuous filaments 11 which are coated, using sizing devices 12, with a nonaqueous sizing capable of reacting under the action of ultraviolet radiation, then which is assembled in the form of wires 14 using an assembly device 13 which can be a comb or an assembly roller with several grooves. The wires are mechanically driven by stretching wheels 15 before being projected and distributed on a moving conveyor 16 transverse to the direction of the projected wires. The wires are then calendered between two rollers 17, 18 before being coated with a binder 19 in the form of thermosetting powder, then the mat consisting of the sheet of wires coated with binder is subjected to infrared radiation within a oven with infrared ramps 20 then with ultraviolet radiation 21. The mat obtained is then wound around a support 22.

The mats obtained according to the present invention have a homogeneous cohesion throughout their thickness and the products reinforced with these mats have a mechanical resistance equivalent to that of the products reinforced with mats produced according to the traditional process by aqueous . The following examples illustrate the mechanical characteristics of polyester composites using, as reinforcements, mats produced according to the invention and also give examples of sizing compositions used in the context of the invention.

EXAMPLE 1

• · Oligomère, silicone uréthane acrylate commercialisé par Union Chimique Belge sous la référence IRR 154   20 %
• · Monomère, uréthane acrylate de type oxazolidone commercialisé par Harcros sous la référence CL 959   20 %
• · N-vinylpyrrolidone   30 %
• · Monomère, triméthylolpropane triacrylate à trois groupements oxyde d'éthylène commercialisé par Cray Vallée sous la référence SR 454   20 %
• · Photoamorceur radicalaire, 1-hydroxy cyclohexyl phénylcétone commercialisé par Ciba-Geigy sous la référence Irgacure 184   4 %
• · Agent de couplage gamma aminopropyl triéthoxy silane commercialisé par Union Carbide sous la référence Silane A 1100   6 %

In this example, the mat is manufactured according to the invention using a size of the following composition, expressed in percentages by weight:

• · Oligomer, silicone urethane acrylate sold by Union Chimique Belge under the reference IRR 154 20%
• · Monomer, urethane acrylate, oxazolidone type marketed by Harcros under the reference CL 959 20%
• 30% N-vinylpyrrolidone
• Monomer, trimethylolpropane triacrylate with three ethylene oxide groups sold by Cray Vallée under the reference SR 454 20%
• · Radical photoinitiator, 1-hydroxy cyclohexyl phenylketone marketed by Ciba-Geigy under the reference Irgacure 184 4%
• · Gamma aminopropyl triethoxy silane coupling agent sold by Union Carbide under the reference Silane A 1100 6%

The binder used is, moreover, a powder binder based on unsaturated polyester marketed by Cray Vallée under the reference Stratyl P 80 A3. It is added to the mat in proportions of 6% by weight of the mat.

Said mat is calendered before depositing the binder by means of a roller, then heated in an infrared oven at 180 ° C and subjected to the action of ultraviolet radiation. The mat obtained is then used to reinforce polyester matrices, at a rate of 58% by weight of glass. The mean breaking stress in bending measured, for the composites obtained, under the conditions defined by the ISO R178 standard, is of the order of 340 MPa, while that obtained under the same conditions and for a substantially identical reinforcement rate, for composites using a mat manufactured according to the traditional method is of the order of 360 MPa, the standard deviations on the series of measurements carried out being of the order of 20 MPa.

EXAMPLE 2

• · Monomère, triméthylolpropane triacrylate à trois groupements oxyde d'éthylène commercialisé par Cray Vallée sous la référence SR 454   25 %
• · Monomère, néopentyl glycol diacrylate propoxylé commercialisé par Union Chimique Belge sous la référence SR 9003   30 %
• · Monomère, ester éthoxylé monoacrylé commercialisé par Cray Vallée sous la référence SR 491   15 %
• · N-vinylpyrrolidone   20 %
• · Photoamorceur radicalaire, 1-hydroxy cyclohexyl phénylcétone commercialisé par Ciba-Geigy sous la référence Irgacure 184   4 %
• · Agent de couplage gamma aminopropyl triéthoxy silane commercialisé par Union Carbide sous la référence Silane A 1100   6 %

In this example, the mat is manufactured according to the invention using a size of the following composition, expressed in percentages by weight:

• · Monomer, trimethylolpropane triacrylate with three ethylene oxide groups marketed by Cray Vallée under the reference SR 454 25%
• Monomer, neopentyl glycol propoxylated diacrylate marketed by Union Chimique Belge under the reference SR 9003 30%
• · Monomer, monoacrylated ethoxylated ester sold by Cray Vallée under the reference SR 491 15%
• 20% N-vinylpyrrolidone
• · Radical photoinitiator, 1-hydroxy cyclohexyl phenylketone marketed by Ciba-Geigy under the reference Irgacure 184 4%
• · Gamma aminopropyl triethoxy silane coupling agent sold by Union Carbide under the reference Silane A 1100 6%

The binder used is, moreover, a powder binder based on unsaturated polyester marketed by Cray Vallée under the reference Stratyl P 80 A3. It is added to the mat in proportions of 6% by weight of the mat.

The mat is prepared in the same way as in Example 1 and the mean breaking stress in bending for a reinforcement rate of the order of 54% is also measured for polyester composites under the conditions defined by ISO standard R178 . The value obtained is of the order of 360 MPa for the composites reinforced using the mat according to the present invention and of the order of 360 MPa also for the composites reinforced using the mat manufactured according to the traditional process, the standard deviations on the series of measurements carried out being of the order of 20 MPa.

The process according to the invention therefore makes it possible to obtain, quickly and economically, mats having satisfactory cohesion and homogeneity in thickness, this cohesion and this homogeneity being in particular favorable for obtaining composite products having a resistance mechanical at least as good as that of the composites obtained using the mats manufactured according to the traditional process by aqueous route.

The mats according to the invention are used, inter alia, to reinforce organic matrices.

Claims (9)

Method for manufacturing a mat formed from a sheet of continuous glass strands emanating from one or more dies, according to which a multiplicity of strands of molten glass in the form of sheets of filaments is drawn from the orifices of each die continuous, the filaments are gathered into at least one wire, each wire being mechanically driven by a drawing system provided with a member ensuring the projection and distribution of said wire on a collecting surface or a conveyor in transverse movement relative to the direction of the projected threads, characterized in that the filaments are coated with a non-aqueous size capable of reacting under the action of actinic radiation and in that the glass threads are subjected, after distribution on the conveyor, to the action of one or more actinic radiations. Method according to claim 1, characterized in that the size used is a size which can be crosslinked under the action of ultraviolet radiation and in that the glass strands are subjected to at least one ultraviolet radiation. Method according to claim 1, characterized in that the size used is a size which can be crosslinked under the action of infrared radiation and in that the glass strands are subjected to at least one infrared radiation. Method according to one of claims 1 to 3, characterized in that a non-aqueous binder capable of reacting under the action of actinic radiation is also projected onto the glass strands. Method according to claim 4, characterized in that the binder used is a binder which can be crosslinked under the action of ultraviolet radiation and in that the glass strands are subjected to at least one ultraviolet radiation. Method according to claim 4, characterized in that the binder used is a binder which can be crosslinked under the action of infrared radiation and in that the glass strands are subjected to at least infrared radiation. Method according to claim 6, characterized in that the binder is in the form of a powder of thermoplastic or thermosetting polymers. Method according to one of claims 4 to 7, characterized in that the glass strands are subjected to a first deposit of binder and to a first irradiation at the level of the first dies then to a second deposit of binder and to a second irradiation on all of them out of the last streams. Method according to one of claims 4 to 8, characterized in that each deposit of binder is preceded and / or followed by calendering and / or needling before being subjected to actinic radiation.

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