FR2711659A1 - Coating composition for direct bonding to thermosetting and laminated materials using such a composition. - Google Patents

Abstract

A composition, useful as a gel layer for coating laminates or as a layer of a thermosetting resin composite material. It comprises, for 100 parts by weight of composition: - from 80 to 95 parts by weight of unsaturated polyester resin or of vinyl ester resin, and - from 5 to 20 parts by weight of an oligomeric polyunsaturated ether. Application to the direct bonding of layers of thermosetting materials without the use of a bonding primer.

Description

COATING COMPOSITION FOR DIRECT HITCHING
ON THERMOSETTING AND LAMINATE MATERIALS
USING SUCH A COMPOSITION

 The present invention relates to the production of laminates coated with a gelled layer called "gel-coat" and composite materials of thermosetting resin.

Usually a thermosetting resin laminate, such as for example a phenolic resin, coated with a gelled layer is manufactured according to a process comprising the following steps - coating of the mold with cold wax, - deposition of a gelled layer, the more often resin-based
unsaturated polyester or vinylester resin and, where appropriate, a
pigment, baked for about 1 hour at 60 ° C
approximately, - spray on the gelled layer, a primer primer
(for example, based on furan resin with a
catalyst) at room temperature (about 200 ° C), - baking for about 30 minutes at about 60 ° C, - cooling to room temperature, - lamination of the thermosetting resin in the mold, - baking for about 90 minutes at about 75 ° C then - cooling to a temperature not exceeding 35 ° C
about and demoulding.

 As is easily understood, the numerical values of temperature and duration at each stage are only exemplary embodiments around which those skilled in the art can envisage variants while obtaining a satisfactory result.

 At least in the case where the thermosetting resin is a phenolic resin, the presence of a primer was previously considered necessary to ensure the integrity of the phenolic structure. However, it is obvious that the application of the primer is a problem both by increasing the number of steps in the laminate manufacturing process and by increasing the overall duration of this process, that is, by decreasing productivity.

Those skilled in the art are therefore looking, in the field of the manufacture of laminates coated with a gelled layer called "gelcoat", a solution to eliminate the application of a primer to hang between said thermosetting resin and said gelled layer without affecting the properties of the laminates, among which the most important to take into account are - the tear resistance of the gelled layer, before and after
aging (natural or accelerated) of the laminate, i.e.
and after subjecting the laminate to temperature changes and
of climate.

- the resistance of the laminate to fire and inflammation.

 Similarly, the manufacture of composite materials combining two layers of thermosetting resins of different natures is often made difficult without the application of a primer between the two layers, unless it adversely affects the properties of the material.

 The present invention is based on the fact that the problem thus exposed can be solved by modifying the constitution of the gelled layer coating a laminate or a layer of a composite material by the incorporation of particular additives in carefully chosen proportions. . Thus conceived, the present invention has proved applicable to laminates and composite materials in which the thermosetting resin may be a phenolic resin or an unsaturated polyester resin.

A first object of the present invention therefore consists of a composition, useful as a gelled layer for coating laminates or as a layer of a thermosetting resin composite material, comprising per 100 parts by weight of composition-80 about 95 parts by weight of unsaturated polyester resin,
or vinyl ester resin, and from 5 to 20 parts by weight of a polyunsaturated ether
oligomer.

 This composition may further comprise, when it is intended for the coating of thermosetting resin laminates (as "gel-coat"), at least one white or colored, mineral or organic pigment, such as those usually used in the constitution. of this kind of gel layers. The proportions of pigment to be used in this case are well known to those skilled in the art depending on the intensity of the hue to be obtained.

 The oligomeric polyunsaturated ether used to modify the gelled layer applied to the laminate or the unsaturated polyester layer of a thermally curable composite maler is the characteristic element of the present invention. Its proportion in the composition according to the invention is a function of the result to be achieved concerning the direct adhesion of the composition (that is to say without the use of a primer layer known in the prior art) on the laminate or on the second layer of thermosetting composite material. It has thus been found that a proportion of less than about 5 parts by weight per 100 parts of composition does not generally achieve the desired purpose while a proportion greater than about 20 parts by weight per 100 parts of composition is generally superfluous. to achieve this goal and, given the high cost of the oligomer relative to the unsaturated polyester resin, would harm the economic efficiency of the invention.

For the purposes of the present invention, the term "oligomer" means a polymer (that is to say according to commonly accepted international definitions such as that of the
Cooperation and Economic Development, a molecule comprising at least 4 repeating units) of low molecular weight, that is to say comprising a small number, for example from 4 to 20, of repeating ether units.

dans laquelle n est un nombre entier allant de 2 à 10. De tels oligomères sont disponibles commercialement auprès de la société
MONSANTO et se présentent sous la forme de liquides incolores.As polyunsaturated ether oligomer it is preferred to use a polyallyl ether such as those of general formula

in which n is an integer ranging from 2 to 10. Such oligomers are commercially available from the company
MONSANTO and come in the form of colorless liquids.

 For the purposes of the present invention, the term "unsaturated polyester resin" is intended to mean the polycondensation product of α, s-ethylenically unsaturated polycarboxylic acids or anhydrides, optionally mixed with saturated polycarboxylic acids or anhydrides, and polyhydric alcohols. hydrous or alkylene oxides.

 The molecular weight of the unsaturated polyester resin is not critical and may vary over a wide range, generally between about 250 and 5000 and more particularly between 350 and 2500. Its hydroxyl group functionality, expressed by the ratio f OH = 2 Wherein IA and IOH are respectively the acid and hydroxyl numbers, must be greater than 1, and preferably at least 1.5. Its water content should not be greater than about 3,000 ppm, preferably not more than about 1,000 ppm.

 Useful unsaturated polycarboxylic acids or anhydrides include maleic, fumaric, chloromaleic, citraconic, metaconic, itaconic, tetraconic or the like or, where they exist, the corresponding anhydrides.

Saturated polycarboxylic acids or anhydrides which can be used to partially replace, for example, up to about 95% by moles, and preferably up to about 45% by moles, the unsaturated acids or anhydrides, especially include orthophthalic, isophthalic, terephthalic and phthalic, succinic, methylsuccinic, adipic, sebacic, tetrabromo-phthalic, tetrachlorophthalic, glutaric, pimelic or the like or, where they exist, the corresponding anhydrides.

 Among the polyhydric alcohols that may be used, saturated aliphatic diols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol and 1,3-butanediol are generally preferred. 1,4-butanediol, tripropylene glycol, pentanediol, hexanediol and neopentyl glycol. Bisphenol A and its alkoxylated derivatives, as well as other aromatic polyols may also be used. Oxides of ethylene and propylene are also usable.

 When the unsaturated polyester resin is prepared from maleic anhydride, it is advantageous to carry out their preparation in the presence of morpholine in order to increase the isomerization rate of the maleate functions to fumarate functions. The amount of morpholine used in this case can be up to 1% by weight, and is preferably between 0.1% and 0.5% by weight of the polyester.

For the purposes of the present invention, the term "vinylester resin" is intended to mean a resin comprising a polymer chain with a terminal reactive double bond, such as an acrylate or methacrylate termination, obtained for example by reaction of acrylic or methacrylic acid with an epoxy resin such as a bisphenol A resin, a phenolic-novolac-epoxy resin or a tetrabromobisphenol A-based resin. Examples of such resins are described in more detail by Matthew B. LAUNITIKIS in
Handbook of Composites, pages 38 to 49.

 The unsaturated polyester resin or vinylester resin used in the composition according to the invention are most often in solution in at least one ethylenically unsaturated monomer with which they can copolymerize in order to generate a crosslinked structure.

This monomer may be chosen from styrene, substituted styrenes such as vinyltoluene, tert-butylstyrene, alphamethylstyrene, chlorostyrene, dichlorostryrene, and lower alkyl (C1 to C8) esters of acrylic acid and methacrylic acid, cyclic acrylates and methacrylates, such as those of cyclohexyl and benzyl, bicyclic methacrylates and acrylates such as those of isobornyl, diallyl phthalate, diallyl maleate, diallyl fumarate, triallyl cyanurate, acetate, crotonate and vinyl propionate, divinyl ether, conjugated dienes such as butadiene-1,3, isoprene, 1,3-pentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1-9-decadiene, 5-methylene-2-norbornene, 5-vinyl-2-norbornene, 2-alkyl-2,5-norbor-nadienes, 5-ethylidene-2-norbornene, 5- (2-propenyl) -2-norbornene, 5- (5-hexenyl) -2 norbornene, 1,5-cyclooctadiene, bicyclo 12,2,2] o α-2,5-diene, cyclopentadiene, 4,7,8,9-tetrahydroindene and isopropylidene tetra-hydroindene, and unsaturated nitriles such as acrylonitrile and methacrylonitrile as well as polyol (meth) acrylates. as the diacrylates and dimethacrylates of ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6 hexane-diol, neopentyl glycol, 1,4-cyclohexane-diol, 1,4cyclohexane-dimethanol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3 propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropylene glycol, trimethylolethane, trimethylopropane, glycerol, pentaerythritol, triacrylates and trimethacrylates of trimethylolethane, trimethylolpropane, triethylglycol, glycerol, pentaerythritol, tetraacrylates and tetramethacrylates of pentaerythritol, di (meth) ac hexa (meth) acrylates of dipentaerythritol, poly (meth) acrylates of mono- or polyethoxylated or mono- or poly-propoxylated polyols such as triethrylate and trimethyol-tripropoxylated trimethyol-propane trimethoxypropyl tripropoxylated trimethylolpropane triacrylate and trimethylolpropane; tripropoxylated glycerol, triacrylate, trimethacrylate, tetraacrylate and tetraethoxylated pentaerythritol tetramethacrylate, and mixtures thereof in all proportions. The amount of ethylenically unsaturated monomer used is preferably between 10 and 50 parts by weight per 100 parts by weight of unsaturated polyester resin.

A second object of the present invention consists of a thermosetting resin laminate coated with a gelled layer based on unsaturated polyester resin and optionally pigment, characterized in that said gelled layer is obtained from a composition such that described above, comprising per 100 parts by weight of composition - from 80 to 95 parts by weight of unsaturated polyester resin
or vinylester resin and - from 5 to 20 parts by weight of a polyunsaturated ether
oligomer.

 The laminate according to the invention is preferably made of a thermosetting resin difficult to coat without primer while maintaining good properties for the laminate. Examples of such resins include, on the one hand, phenolic resole or novolac resins and, on the other hand, certain grades of unsaturated polyester resins known as low-volatile-content resins. Among the latter, mention may be made in particular of those compliant with the patent application EP-A-369,683 or the patent application WO 93/08235.

 In the laminates according to the invention, the thermosetting resin may be mechanically reinforced by the addition of from about 20% to about 80% of its own weight of glass fibers (of variable length 5 to about 50 mm), asbestos, carbon or polyamide.

Another subject of the present invention consists of a composite material comprising at least one layer of a first thermosetting resin and at least one layer of a second thermosetting resin, characterized in that it comprises, arranged between the two said layers, a layer obtained from a composition as described above, comprising per 100 parts by weight of composition - from 80 to 95 parts by weight of unsaturated polyester resin
or vinylester resin, and - from 5 to 20 parts by weight of an ether / polyunsaturated
oligomer.

 In the composite material according to the invention, at least one of the two layers of thermosetting resin is preferably composed of a thermosetting resin difficult to coat without primer while maintaining good properties for the composite material. Examples of such resins have been provided above.

 In the composite material according to the invention, the first thermosetting resin and the second thermosetting resin may be identical but preferably they will be chosen of different types in two adjacent layers bonded by the intermediate layer of composition according to the invention. For example, it may be a material combining a phenolic resin layer with a layer of unsaturated polyester resin.

 In this way, the present invention makes it possible to solve the so-called lamination recovery problem, which is encountered especially in the manufacture of boat hulls made of composite materials, that is to say the difficulty of having a layer of phenolic resin on a layer of unsaturated polyester resin already polymerized unless applying a primer.

An example of a process for obtaining a laminate according to the invention comprises the following steps: coating of the mold (made of metal or of composite material) with
cold wax, - application on the mold, for example by spraying,
a composition layer according to the invention comprising in
in addition to a polymerization catalyst and, where appropriate, a pigment
and / or a release agent, - polymerization of the composition layer according to the invention at a
temperature between about 15 ° C and 700 ° C for a period
duration between about 3 and 75 minutes, - application on the polymerized layer of the composition according to
the invention, at least one thermosetting resin
possibly reinforced with fibers and containing at least one
polymerization catalyst, - polymerization of said thermosetting resin to a
temperature between 40 ° C and 800 ° C during a
time between 1 and 5 hours, and - cooling to a temperature not exceeding 35 ° C.
about and demoulding.

 As is easily understood, the characteristic element of the process according to the invention lies in the choice, as composition based on unsaturated polyester resin or vinylester resin usable for direct application on the mold and before the direct coupling of the thermosetting resin, of a composition as described above, comprising a selected proportion of oligomeric polyunsaturated ether.

 The polymerization catalyst added to the composition according to the invention is an agent capable of forming free radicals at the polymerization temperature (approximately 150 ° C. to 700 ° C.) in the subsequent step. Suitable agents include, inter alia, organic peroxides, peroxydicarbonates and peroxyesters such as benzoyl peroxide, tertiary butyl hydroperoxide, tertiary butyl peroxide, dicumyl peroxide and 2,2 bis (tert-butylperoxy). ) butane, paracetal, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, tertiary butyl perbenzoate, tertiary butyl peroxyoctoate, tertiary butyl peroxy isopropylcarbonate, tertiary butyl perisononanoate tertiary butyl permalteinate, cyclic peracetal, 2,5-dimethyl-2,5-bis (2-ethylhexolperoxy) hexane, methyl ethyl ketone peroxide, tert-amyl peroxyoctoate, 2,5-diperoxyoctoate, or peroxide. 2,4-pentanedione. An effective amount of this polymerization catalyst is preferably between 0.5% and 5% by weight of the weight of the composition to be polymerized.

The application, after polymerization-gelling of the composition according to the invention, of the thermosetting resin optionally reinforced with fibers and of its polymerization catalyst can be carried out by any known technique such as: - contact lamination, usually manual , - simultaneous projection, - continuous heat molding (used in particular in the manufacture
of plates), - resin transfer molding, - pultrusion, - filament winding.

 The polymerization catalyst of the thermosetting resin is of course chosen depending on the nature of this resin.

In the case of a phenolic resin it may be either a basic catalyst or an acid catalyst, usually a strong inorganic organic acid.

 Due to its main characteristic, the method according to the invention allows an appreciable time saving, and therefore an improvement in productivity, by eliminating the intermediate step of spraying a primer.

 An example of a process for obtaining a composite material according to the invention comprises, before the lamination of at least one layer of a thermosetting resin, the application of a layer of composition according to the invention further comprising a polymerization catalyst and optionally reinforcing fibers, and then the polymerization of said layer at a temperature of between about 15 ° C. and about 400 ° C. for a time of between about 3 and 10 minutes, as in the preceding case (obtaining a laminate), the method according to the invention most often comprises coating the mold (made of metal or composite material) with a release agent such as wax, as is well known to those skilled in the art, the layer of the thermosetting resin contains at least one polymerization catalyst for lamination purposes and may further be reinforced by glass fibers (of variable length 5 to about 50 mm), asbestos, The polymerization of this layer occurs under conditions of temperature and duration well known to those skilled in the art, depending on the nature of the thermosetting resin concerned and the thickness of the layer that the we want to get.

 This process makes it possible to obtain composite materials combining thermosetting resins between which the adhesion is very poor in the absence of a primer without substantially lengthening the manufacturing process.

 As is easily understood, obtaining gelled layer-coated laminates and obtaining composite materials are two aspects of the same concept of the invention consisting in applying the composition according to the invention, as a coating, to at least one layer of thermosetting material.

 The following examples are provided for purely illustrative and non-limiting purposes of the present invention.

EXAMPLE 1
In a mold coated with cold wax, is applied to the gun a layer of thickness about 400 Rm of a composition comprising (per 100 parts by weight) - 78.4 parts by weight of a polyester gel coat marketed by the
NESTE OY company under the name SKIN COAT 793 V 6, - 19.6 parts by weight of a polyallyl ether sold by
the MONSANTO company under the name SANTOLINK XI 100, and - 2 parts by weight of a methyl ethyl ketone peroxide
marketed by AKZO under the name
BUTANOX M 50.

This layer is polymerized at ambient temperature (200 ° C.) for one hour and then a mixture comprising (per 100 parts by weight) - 30 parts by weight of glass fibers - 65.5 parts by weight of this polymer layer is applied. a phenolic resin of resol type
marketed by the company CRAY VALLEY SA under the
NORSOPHEN N 1205, and 4.5 parts by weight of an acid catalyst
65% para-toluenesulfonic acid in water.

 This mixture is polymerized at 80 ° C for 90 minutes, and then cooled to 30 ° C prior to demolding the laminate.

 The gel-coated surface of the phenolic laminate thus obtained is subjected to a peel test of sticking a metal pellet on the gel-coat using a polyurethane glue and then, 24 hours after drying the glue, to be measured the pulling force by means of a DYNATEST device. In this case the pullout force is 2100 N.

EXAMPLE 2
The process of Example 1 is reproduced with the exception of the composition of the spray coat, which is now (per 100 parts by weight) - 88.2 parts by weight of SKIN COAT 793 V 6 gel coat 9.8 parts by weight of SANTOLINK XI 100, and 2 parts by weight of BUTANOX M 50.

 Under these conditions the tearing force, measured as in Example 1, is equal to 1500 N.

EXAMPLE 3
In a mold coated with cold wax, a layer comprising (for 100 parts by weight) - 98 parts by weight of an unsaturated polyester resin is applied first.
marketed by the company CRAY VALLEY SA under the
NORSODYNE S 49021 TAIE and containing 1500 ppm
paraffin as a reducing agent for emissions of substances
volatile, and - 2 parts by weight of BUTANOX M 50.

 After polymerization at room temperature (20 ° C.) of this first layer, a second layer comprising (for 100 parts by weight) - 88.2 parts by weight of the resin NORSODYNE S 49021 TAIE, - 9.8 parts by weight is applied. of SANTOLINK XI 100, and - 2 parts by weight of BUTANOX M 50.

 After polymerization at room temperature (20 ° C.) of this second layer, it is possible to demould the resulting composite material.

 By conducting tensile shear tests of specimens of this composite material, it is verified that there is good adhesion between the two layers of the material. Indeed, the break during the tensile test always occurs at one or the other of the two layers, but never at their interface.

Claims (7)

A composition useful as a gelled layer for coating laminates or as a layer of a thermosetting resin composite material, comprising per 100 parts by weight of composition - from 80 to 95 parts by weight of unsaturated polyester resin and from 5 to 20 parts by weight of an oligomeric polyunsaturated ether. 2. Composition according to claim 1, carctérisée in that it coprcn in excess niolns a plgcnt, white or colored, mineral or organic. 3. Composition according to one of claims 1 and 2, characterized in that the oligomeric polyunsaturated ether is a polyallyl ether of general formula

 in which n is an integer from 2 to 10. 4. Composition according to one of claims 1 to 3, characterized in that the unsaturated polyester resin is in solution in at least one ethylenically unsaturated monomer with which it can copolymerize. 5. Composition according to claim 4, characterized in that the amount of ethylenically unsaturated monomer is between 10 and 50 parts by weight per 100 parts by weight of unsaturated polyester resin. 6. Thermosetting resin laminate coated with a gelled layer based on unsaturated polyester resin and optionally pigment, characterized in that said gelled layer is obtained from a composition according to one of claims 1 to 5. A composite material comprising at least a first layer of a thermosetting resin and at least a second layer comprising an unsaturated polyester resin, characterized in that said second layer is obtained from a composition according to one of claims 1 to 5.