SI9200362A - Improved unsaturated polyester resin compositions for moulding - Google Patents

Abstract

Moulding composition containing at least one unsaturated polyester prepolymer, at least one ethylenically unsaturated monomer, at least one at least difunctional isocyanate, at least one inorganic filler and at least one blocking agent for the isocyanate functional group. The blocking agent is an unsaturated compound capable of regenerating the isocyanate functional group at a temperature not exceeding approximately 120 DEG C and of taking part in the formation of the three-dimensional network by copolymerising with the double bonds of the ethylenically unsaturated monomer and/or of the unsaturated polyester prepolymer. Application to a process for the manufacture of moulded articles.

Description

Improved compositions of unsaturated polyester casting resins

The present invention relates to the modification of unsaturated polyester resins with blocked isocyanates to provide casting compositions with improved properties.

Unsaturated polyester resins are used in many applications, especially for casting fiberglass reinforced objects. They are widely used in the manufacture of automotive parts, bathroom materials and accessories, cases for electronic appliances, hulls, kitchen supplies and furniture pieces. However, they have the disadvantage that, due to other thermally curable polymers, their mechanical properties are sometimes insufficient, especially in terms of impact behavior, toughness, and elongation at break. However, they can improve the mechanical properties of unsaturated polyester resins by introducing polyisocyanate. This reacts with the finite alcoholic functions of the polyester prepolymer to form urethane bonds, which have this peculiarity to improve the toughness of the net obtained after polymerization.

The fact that the isocyanate functions react immediately with the hydroxyl functions of the polyester does not allow them to batch the reactive polyester-isocyanate mixture into a single container. So, they recommended the use of different compounds to block isocyanate groups. It is known that when a polymer with blocked terminal isocyanate groups is heated, the unblocking reaction and release of the compound used to block the isocyanate groups occur. Thus, FR-A-2 568 884 describes polymer compositions comprising:

polyurethane obtained by the reaction of the primary diamine as a chain extender with a polyether or polyester type isocyanate function prepolymer,

041292 blocked with a cetoxime containing double bonds and a polymer of this cetoxime.

This document describes in detail that the unblocking reaction occurs when the mixture of the blocked prepolymer with primary diamine is heated to a temperature of the order of magnitude from 60 ⁰ to 120 ° C. The vinyloxime used for blocking is then released and polymerized, then the preferentially obtained polymer is finally crosslinked.

Otherwise, FR-A-2,293,460 describes a process for the manufacture of thermally curable coatings by which a blocked, at least bifunctional isocyanate is incorporated into a polymer with free hydroxyl groupings, characterized in that the isocyanate blocks the hydroxamic acid ester or acylhydroxamate. In such a process, the isocyanate thus blocked is almost completely unblocked in less than about 30 minutes at a temperature of about 130 to 140 ° C.

The problem to be solved by the present invention, therefore, is to improve the properties of the unsaturated polyester casting resins by introducing a polyisocyanate and an isocyanate blocking agent which does not remain in the network after the isocyanate is unblocked, thus favorable kinetics at low temperature.

In order to avoid that the reactive mixtures of polyester polyisocyanate cannot be batched in one container, therefore, the present invention is a casting composition containing at least one unsaturated polyester prepolymer, at least one ethylene unsaturated monomer, at least one bifunctional isocyanate, at least one mineral filler, and at least one agent that blocks isocyanate function, characterized in that the blocker is an unsaturated compound capable of regenerating isocyanate function at a temperature not exceeding about 120 ° C and involved in the formation of a three-dimensional network by copolymerization with double bonds of ethylene unsaturated monomer and / or unsaturated polyester prepolymer. In the context of the chemical reaction of the blocking agent, the formation of the mesh prevents the problems of plasticization and possible expansion at high temperature.

The composition of the invention, which is stable at room temperature, leads to the combined effect of increasing the temperature and decomposing the radicals to form a hybrid polyester polyurethane network. Its use makes it possible to obtain, after casting, finished products that have excellent mechanical properties in terms of bending modulus, breaking stress, impact behavior and thermal behavior.

Favorable results were obtained using hydroxamates of the following general formula

0

1 2 92

R - C-NH ^ O-iOn_R2 in which n = 0 or 1, as agents for blocking the isocyanate functions, and R 2 each represent a hydrocarbon group having 1 to 20 carbon atoms and at least one of R ₁ and R carries at least one ethylenically unsaturation. R _x and R ₂ may be alkyl, aralkyl, aryl or cycloalkyl groups, carriers of one or more ethylene unsaturation and, optionally, substituents, such as e.g. halogen atoms (fluorine, chlorine, bromine or iodine), nitro, cyano and / or alkoxy.

Those compounds whose preparation is described in patent FR-A-2,293,460 are capable of regenerating isocyanate function at a temperature from about 70 ° C to 100 ° C over a period of about 1 minute to several hours. Benzylmethacrylohydroxamate and allylmethacrylohydroxamate are particularly effective examples.

The organic polyisocyanate useful in the casting compositions of the invention may be bifunctional, trifunctional and up to six-functional. It may be aliphatic, cycloaliphatic and / or aromatic. Examples include, for example, 4,4'-diphenylmethane diisocyanate, 2,4- and 2,6-toluenediisocyanate, isophorone diisocyanate, tetramethylenediisocyanate, pentamethylene-diisocyanate, hexa-methylene-diisocyanate, 4,4'dicyclohexylmethane-diisocyanate, . It can also be used in the form of a low molecular weight polyurea or polyurethane type prepolymer, i.e. by reacting one of the above polyisocyanates with a polyamine or a low molecular weight polyol. In the latter case, it is preferable to use alkylene glycol, such as dipropylene glycol, tripropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, neoptentyl glycol,

1,2- and 1,3-butylene glycol. It can also be used in the form of urethonimine by heating one of the above polyisocyanates to an elevated temperature in the presence of a phosphorus catalyst to form a polycarbodiimide, and then reacting the latter with another isocyanate group, e.g. as described in US-4014935.

ί 292

By the unsaturated polyester resin of the present invention is meant the product of polycondensation of polycarboxylic acids or anhydrides, a, b-ethylene unsaturated, optionally in admixture with saturated polycarboxylic acids or anhydrides, and polyhydric alcohols or alkylene oxides.

Useful unsaturated polycarboxylic acids or anhydrides include in particular maleic, fumamo, chloromaleic, citraconic, methaconic, itaconic, tetraconic acid or the like or, if any, suitable anhydrides. Saturated polycarboxylic acids or anhydrides useful for partial replacement, e.g. up to about 95 mol%, preferably up to about 45 mol%, of unsaturated acids or anhydrides, comprising in particular orthophthalic, isophthalic, terephthalic, succinic, methylanthane, adipic, sebacic, tetrabromophthalic, tetrachlorophthalic, glutamate, pimelic acid or the like, or , the corresponding anhydrides.

Useful polyhydric alcohols are generally preferred saturated aliphatic diols, such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butanediol, 1,4-butanediol, tripropyleneglycol, pentanediol glycol, pentanediol, and pentanediol. Bisphenol A and its alkoxyl derivatives as well as other aromatic polyols can also be used. Ethylene oxide and propylene oxide are also useful.

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

The molecular weight of the polyester is not critical and can vary over a considerable range, generally between about 250 and 5000, and in particular between 350 and 2500.

Functionality of hydroxyl grouping, expressed by the relation f _OH = 2I _QH + I _OH , where I _A and Ι _θΗ acid or. the hydroxyl number must be greater than 1 to make the modification of the isocyanate-blocked polyester network effective.

Another component of the casting composition of the invention is an ethylene unsaturated monomer copolymerizable with unsaturated polyester to form a crosslinked structure. This monomer can be selected from the following, such as styrene, substituted styrene, such as vinyltoluene, tert-butylstyrene, α-methylstyrene, chlorostyrene, dichlorostyrene, lower

1 2 92 Acrylic and methacrylic acid alkyl esters, cyclic, such as cyclohexyl- and benzyl-, -acrylates and -methacrylates, bicyclic, such as isobomyl-, -methacrylates and -acrylates, diallyl phthalate, diallyl maleate, diallyl fumarate, trialylcyanurate, vinyl acetate, vinyl 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-2norbornene, 2-alkyl-2,5-norbornadienes, 5-ethylidene-2-norbornene, 5- (2-propenyl) -2norbomen, 5- (5-hexenyl) -2-norbomen, 1,5-cyclooctadiene, bicyclo [2.2.2] octa-2,5diene, cyclopentadiene, 4,7,8,9- tetrahydroindene and isopropylidene-tetrahydroindene, and unsaturated nitriles such as acrylonitrile and methacrylonitrile, as well as (meth) acrylates of polyol, such as diacrylates and dimethacrylates of ethylene glycol, propylene glycol, 1,3-butanediol, 1,4butanediol, 1,6-hexanediol, 1,6-hexanediol, , 4-cyclohexanediol, 1,4cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-2-methyl-1,3-propanediol,

2,2-diethyl-3-propenethiol, 3-methylphenol, 3-methoxyphenol, 3-methoxyphenol, 3-methylphenol di (meth) acrylates to hex (meth) acrylates of dipentaerythritol, poly (meth) acrylates of mono- or polyethoxylated or mono- or polyproxylated polyols, such as triacrylate and trimethacrylate of triethoxylated trimethylolpropane, tripropoxylated trimethylacrylate, triacrylate, triacrylate, triacrylate, triacrylate tetraacrylate and tetramethacrylate of tetraethoxylated pentaerythritol, and mixtures thereof in all ratios.

The casting composition of the invention also comprises at least one mineral filler. It may be powdered, such as calcium carbonate, alumina hydrate, kaolin or talc, and may be present in a proportion of about 25 to 350 weight percent. parts per 100 wt. parts of unsaturated polyester prepolymer and ethylene unsaturated monomer. The casting composition of the invention may also comprise a massive mineral filler such as glass beads or fibers in a proportion of from about 5 to 40% by weight of the total weight of the composition of the invention.

In order to modify the mechanical properties of the unsaturated polyester resin, compounds capable of reacting with regenerated isocyanate functions can be incorporated into the composition of the invention, thus forming a copolymer with an unsaturated polyester prepolymer. In this context, we can envisage the use of compounds with terminal hydroxyl groupings that react with isocyanate groups to form urethane bonds such as e.g. aliphatic or aromatic glycols selected from 1,2-propanediol (propylene glycol),

4 1 2 92 dipropylene glycol, diethylene glycol, ethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, triethylene glycol, tripropylene glycol, hydroxyethyl ether-hydroquinone, ethoxylated bisphenol A, propoxylated bisphenol A. Hydroxyl groups with copolymers may also be used saturated polyesters, such as polycaprolactone, polyester amides, polyamides containing hydroxyl groupings, polyethers and polythioethers with finite hydroxyl groupings, phenol-aldehyde resins, urea-aldehyde resins and epoxy resins. We can also use compounds that have amine functions and that react with isocyanate functions to form urea bonds, such as e.g. diaminodiphenylmethane, isophorondiamine, diaminodiphenyl sulfone, methylene-bis4,4 '- (2,6-diisopropylaniline), methylene-bis-4,4' - (2,6-diethylaniline), diethyldiaminotoluene, methylene-bis-4,4 ' - (ethyl-2-methyl-6-aniline), trimethylene glycol-di-p-aminobenzoate, methylenebis-5,5 '- (2-amino-o-methyl-benzoate) and isobutyl-4-chloro-3,5- diaminobenzoate, polymers, carriers of amine groups, and poly (oxytetramethylene) -di-p-aminobenzoate.

The casting composition of the invention preferably comprises at least one agent capable of forming radicals at a temperature higher than or equal to the unblocking temperature (regeneration of isocyanate function) of the blocked isocyanate. Suitable agents include, but are not limited to, organic peroxides, peroxydicarbonates and peroxyesters, such as benzoyl peroxide, tert-butyl hydroxide, tert-butyl peroxide, dicumyl peroxide, 2,2-bis (tert-butyl peroxy) butane, paracetal, l, l- bis- (t-butyl peroxy) -3,3,5-trimethylcyclohexane, tert-butyl perbenzoate, tert-butyl peroxy octoate, tert-butyl peroxy isopropylcarbonate, tert-butyl perizononanoate, tert-butyl permaleinate, cyclic peracetal, 2,5-dimethylacetal 5-bis (2-ethylhexolperoxy) -hexane, methylethyl cetone peroxide, tert.amyl peroxyctoate, 2,5-diperoxyctoate or another 2,4pentanedione peroxide.

The casting composition of the invention may include, but are not limited to:

an effective amount of at least one cross-linking inhibitor. Examples of useful cross-linking inhibitors include, in particular, phenothiazine, methyl-hydroquinone, Ν, diet-diethylhydroxyamine, nitrobenzene, di-tert-butyl catechol, hydroquinone, p-anilinophenol, di- (2-ethylhexyl) -octylphenyl-phosphite, 2,5- diterc.butyl-4-hydroxytoluene, methylene blue and mixtures thereof in all ratios. The effective amount of crosslinking inhibitor is generally between 0.01 and 0.2% by weight of unsaturated polyester resin;

at least one catalyst for the formation of urethane, such as tin dibutyldylaurate; at least one catalyst for the reaction of isocyanate functions with unsaturated polyester

4 1 2 92 resin which can be selected from the following such as:

(a) Tertiary amines such as bis (dimethylaminoethyl) ether, trimethylamine, triethylamine, Nmethylmorpholine, N-ethylmorpholine, N, N-dimethylbenzylamine, N, N-dimethylethanolamine, N, N, N ', N'-tetramethyl-1,3, 3 -butandiamine, triethylanolamine, 1,4-diazabicyclo [2.2.2] octane and pyridinoxide, (b) tertiary phosphines, such as trialkylphosphines and dialkylbenzylphosphines, (c) strong bases, such as alkali and alkaline earth metal hydroxides, alcoholates and phenolates, (d) metal salts of strong acids such as iron, tin (IV), tin (II) and bismuth chloride, antimony trichloride and bismuth nitrate, (e) chelates such as may be obtained from acetylacetone, benzoylacetone, trifluoroacetylacetone, ethylacetoacetate, salicylcarbonydehyde , acetylacetoimine, bis-acetylacetonalkylenediimine, salicylaldehydeimine and metals such as beryllium, magnesium, zinc, cadmium, lead, titanium, zirconium, tin, arsenic, bismuth, chromium, molybdenum, manganese, iron, cobalt and nickel, (f) alcoholates and metal phenolates such as Ti (OR) ₄ , Sn (OR) ₄ , Sn (OR) ₂ and A1 (OR) ₃ in which R is an alkyl or aryl group, (g) salts of organic acids and metals such as alkali and alkaline earth metals, aluminum, tin, lead, manganese, cobalt, nickel and copper, e.g. sodium acetate, potassium laurate, calcium hexanoate, tin (II) acetate, octoate and oleate, lead octoate, manganese naphthenate and cobalt naphthenate, and (h) ferrous and cobalt metal carbonyls and organometallic derivatives of tetravalent tent, trivalent and petroleum, bismuth; among these derivatives, the most preferred are the dialkyl tin carboxylic acid salts such as dibutyltin diacetate, dibutyltin diavolate, dibutyltin maleate, dinitrolitin diacetate, dioctyltin diacetate, dibutinitroxytetinetroxybenzylate, 2bt, 2bt; dialkyl tin dialkoxides and dialkyl tin dichlorides.

This catalyst is generally used in the proportion of 0.01 to 2% by weight of the polyisocyanate present in the first mixture.

at least one flame retardant, such as alumina hydrate, at least one organic or mineral pigment and at least one non-reactive thermoplastic resin, such as polystyrene or methylpolymethacrylate, capable of reducing the shrinkage of unsaturated polyester resin,

041292 batched during casting. Such a resin can be introduced as a solution into the monomer as styrene;

at least one thixotropic agent, such as colloidal silica or pyrolysed clay, in a proportion of from about 0.5 to 1.5 wt. parts per 100 parts of the composition.

In the casting composition of the invention, the proportions of the components per 100 wt. parts of unsaturated polyester prepolymer are generally as follows:

from about 50 to 300 wt. parts of ethylene unsaturated monomer, the amount of at least bifunctional isocyanate such that the molar ratio of isocyanate functions to hydroxyl functions of the unsaturated polyester prepolymer is between about 0.8 and 1.2, and the amount of blocking agent such that the molar ratio of blocking functions to isocyanate functions is at least 1 .

The second object of the present invention consists of a process for making cast pieces of batch polyester unsaturated resin, characterized in that the composition, as previously described, is cast into a mold at sufficient temperature and sufficient time to regenerate isocyanate function and form a three-dimensional network. The process of the invention can be applied by success to obtain composite thermosetting pieces, either by the sheet casting technique (called SMC) or by the mass casting technique (i.e. BMC) or the resin transfer technique (so-called RTM) or the reaction technique injection molding (ie RIM). The duration of the casting process of the invention is, of course, a function of the individual nature of the blocker selected and the temperature selected. It is generally between about 0.5 and 30 minutes, especially in the case where the blocking agent is hydroxamate as described above. The temperature used during the casting process of the invention is generally at least 70 ° C and can reach e.g. gradually, about 200 ° C. The process of the invention can be carried out in a casting machine operating at a pressure of from about 20 to 200 bar.

Specifically, where there is a process of the invention of casting a leaf casting composition, it generally comprises the following steps:

(a) preparation of a mixture containing at least one mineral powder filler, at least one unsaturated polyester resin, at least one ethylene unsaturated monomer, at least one organic polyisocyanate and at least one agent capable of forming free radicals, (b) simultaneous distribution in the apparatus for the production of sheets of the mixture prepared in step (a), on the one hand, and long fiberglass, on the other, so that '04 1 2 92 yields, at the outlet of the apparatus, sheets of doughy consistency which can be cut to the desired length, (c) maintaining the obtained leaves of step (b) at a temperature between about 20 ° C and 50 ° C for at least about 12 hours to obtain a stabilization of their viscosity, (d) transferring the obtained leaves with stabilized viscosity from step (c) to the mold, and ( e) casting the sheets by compressing them to a temperature preferably between about 100 ° C and 180 ° C in sufficient time to initiate crosslinking of the unsaturated polyester resin with the ethylene unsaturated monomer.

When exiting step (e), the crosslinked material may, inter alia, be subjected to a post-crosslinking phase at a temperature preferably between about 150 and 180 ° C and preferably between about 10 and 120 minutes. The duration of casting of step (e) depends, of course, on the proportions of the components of the mixture prepared in step (a) as well as on the dimensions and thickness of the leaves, but is generally between about 1 and 10 minutes.

When the process of the invention consists of casting a mass-castable composition, it generally comprises the following steps:

(a) preparation of a mixture containing at least one mineral powder filler, at least one unsaturated polyester resin, at least one ethylene unsaturated monomer, at least one organic polyisocyanate and at least one agent capable of forming free radicals, (b) simultaneous distribution in the apparatus for a mixture of mixtures prepared in step (a) on the one hand and short glass fibers on the other, (c) transfer of the moldable composition obtained in step (b) into the mold and (d) casting the composition at a temperature of preferably between about 100 ⁰ and 180 ° C for a duration sufficient to trigger crosslinking of the unsaturated polyester resin with the ethylene unsaturated monomer.

When leaving step (d), the crosslinked material may, inter alia, be subjected to a post-crosslinking phase at a temperature of preferably between about 150 and 180 ° C and for a duration of preferably between about 10 and 120 minutes. The duration of casting of step (d) depends, of course, on the proportions of the components of the mixture prepared in step (a) as well as on the dimensions of the casting to be fabricated, but is generally between about 1 and 10 minutes.

041292

This process can be carried out discontinuously for casting BMC, in which steps (a) and (b) can be combined into a single stage, introducing short glass fibers, in this case a size not exceeding 6 mm preferably, into the mixer at the same time as the others the ingredients of the castable compound. It can also be carried out continuously for casting continuously impregnable compositions (also labeled CIC after the corresponding English abbreviation), in which case step (b) is distinctive and follows step (a), and it is preferable that between steps ( b) and (c) maintain the composition at a temperature between about 20 ⁰ and 50 ° C for at least about 12 hours to stabilize the viscosity. In one or the other variant - continuous or discontinuous - casting can be carried out during step (d), either by injection or by compression.

Finally, there is the last object of the present invention from non-saturated polyester resin castings with fillers obtained from the compositions of the invention (as described previously) or by using the manufacturing process described previously.

The following examples illustrate, but are not limited to, the present invention. Unless otherwise stated, all amounts of the substance are expressed in parts by weight.

The various unsaturated polyesters used in the examples below are as follows:

Polyester I

It is obtained by polycondensation of 98 parts of maleinanhydride and 84 parts of propanediol to give a numerical average molecular weight of 1500. Its acid number is 31 and hydroxyl number is 53. It is then diluted in styrene to a dry extract of 66% in the presence of hydroquinone used as an inhibitor.

Polyester II

It is obtained by polycondensation of 98 parts of maleinanhydride and 101 parts of propanediol to give a numerical average molecular weight of 1500. Its acid number is 8 and hydroxyl number 72. It is then diluted in styrene to a dry extract of 70% in the presence of hydroquinone used as an inhibitor.

Polyester III

It is obtained by polycondensation of 88 parts of maleic anhydride, 99 parts of isophthalic acid and

041292

174 parts of diethylene glycol to give an average molecular weight of about 2800. Its acid number is 5 and its hydroxyl number is 35. It is then diluted in styrene to a dry extract of 65% in the presence of hydroquinone used as an inhibitor.

EXAMPLE 1 (Comparative)

To 100 parts of polyester I was added 200 parts of chalk (CaCO ₃ ), 0.002 parts of parabenzoquinone, 1.5 parts of tert.butylperbenzoate. Stir this mixture vigorously, then pour into a compression mold. The crosslinking is then carried out by bringing the temperature to 150 ° C under a pressure of 100 bar for 5 minutes.

The glass transition temperature of the resulting grid is determined by viscoelastic measurements, taking the temperature of the maximum of the mitigation peak at a frequency of 1 Hz. Static mechanical properties are determined by a three-point bending test.

Tg 200 ° C Bending Module (NFT 51.001) 8300 MPa Bending Fracture Tension (NFT 51.001) 58 MPa Not Cut Shock Result (NFT 51.911) 3.9 kJ / m ²

EXAMPLE 2

Polyester I is introduced into the reactor maintained at 80 ° C. Then diphenylmethane diisocyanate with functionality 2.7, DOW CHEMICAL with MDI code M580 is introduced by continuous casting, so that we have 2 moles of isocyanate per 1 mole of alcohol function of polyester . When all alcohol functions are reacted, benzylmethacrylhydroxamate is introduced in the stoichiometric portion. The reaction is stopped when more than 95% of the remaining isocyanate functions are blocked. The resulting mixture was cooled to room temperature. Then add an amount of polyester I equal to the amount initially introduced into the reactor.

EXAMPLE 3

100 parts of chalk (Millicarb), 0.002 parts of parabenzoquinone, 1 part of zinc naphthanate and 1.5 parts of tert.butylperbenzoate are added to 100 parts of the reactive mixture of Example 2. That

041292 Stir the mixture vigorously, then pour into a compression mold. This is followed by the unblocking of the isocyanate, followed by its reaction with the free hydroxyl functions of the polyester by means of a differential scanning calorimeter: a peak corresponding to the unblocking temperature of the isocyanate is observed at 100 ° C. The networking is carried out as in Example 1. The properties obtained are as follows:

Tg 190 ° C Bending Module (NFT 51.001) 9800 MPa Bending Burst Tension (NFT 51.001) 78 MPa Uncut Shock Output (NFT 51.911) 6 kJ / m ²

EXAMPLE 4

We operate in the same manner as in Example 3 except that tert.butylperbenzoate is replaced by an equivalent amount of diter.butyl peroxide. The properties of the material obtained are as follows:

Tg 190 ° C flexural modulus (NFT 51.001) 10000 MPa Fracture flexural stress (NFT 51.001) 90 MPa not cut Shock output (NFT 51.911) 6 kJ / m ²

EXAMPLE 5

Introduce 555.2 g of styrene, 272 g of polyisocyanate, supplier D0W CHEMICAL under the code MDI M 220, 183.2 g of benzylmethacrylohydroxamate and 0.15 g of parabenzoquinone into the reactor maintained at 80 ° C. After 3 hours at 80 ° C, the mixture was cooled to room temperature, where it was found by chemical determination that the isocyanate functions were completely blocked.

EXAMPLE 6

232 g of blocked isocyanate of Example 5 was added to 500 g of polyester II. 1464 g of CaCO ₃ , 0.1 g of parabenzoquinone, 0.5 g of zinc naphthenate and 0.75 g of diterbutyl peroxide are then added. The reactive mixture was stirred vigorously, then poured into a compression mold. Then crosslink as in Example 1. The properties obtained are as follows:

041292

Tg flexural modulus (NFT 51.001) Fracture flexural stress (NFT 51.001) not cut Shock output (NFT '51.911)

205 ° C 9700 MPa 68 MPa 5.5 kJ / m ²

EXAMPLE 7

To 100 parts of polyester III 200 parts of chalk and 1.5% of diter.butyl peroxide are added. Stir the mixture vigorously, then pour into a compression mold. The crosslinking was then carried out as in Example 1. Resistance to unbuttoned Insulation of the resulting plates is 8.4 kJ / m ² . Their temperature is 90 ° C.

EXAMPLE 8

Mix 85 parts by weight of polyester III and 15 parts by weight. parts of polycaprolactone, supplied by Interox Chemical under the code CAPA 212. To this mixture, the required amount of blocked isocyanate of Example 5 is added to obtain a molar ratio of blocked isocyanate functions / alcohol function 1.

The resulting mixture was added 200 wt. parts of chalk, 1% by weight of zinc naphthanate and 1.5% of diterbutyl peroxide. After polymerization under the conditions described above, plates with the following properties are obtained:

Claims (16)

A casting composition comprising at least one unsaturated polyester prepolymer, at least one ethylene unsaturated monomer, at least one bifunctional isocyanate, at least one mineral filler and at least one agent that blocks isocyanate function, characterized in that the blocking agent is an unsaturated compound, capable of regenerating isocyanate function at a temperature not exceeding 120 ° C and participating in the formation of a three-dimensional network by copolymerization with double bonds of ethylene unsaturated monomer and / or unsaturated polyester prepolymer. Casting composition according to claim 1, characterized in that hydroxam of the following general formula is used 0 0 II II R, - C-NH-O- (C) n_R2 in which n = 0 or 1, as agents for blocking isocyanate function. R _x and R ₂ represent each hydrocarbon group with 1 to 20 carbon atoms and at least one of R _x and R 4 carries at least one ethylene unsaturation. Casting composition according to claim 2, characterized in that R _x and R _{2 are} selected from alkyl, aralkyl, aryl or cycloalkyl groups, carriers of one or more ethylene unsaturation, optionally substituents, such as halogen atoms, nitro, cyano and / or alkoxy groups. Casting composition according to claim 2, characterized in that the isocyanate function blocking agent is selected from benzylmethacrylohydroxamate and allylmethacrylohydroxamate. Casting composition according to one of claims 1 to 4, characterized in that the mineral filler is a powder filler present in a proportion of 25 to 350% by weight. parts per 100 wt. parts of a non-saturated polyester prepolymer and an ethylene-unsaturated monomer. Casting composition according to one of Claims 1 to 5, characterized in that it contains, inter alia, a massive mineral filler present in a proportion of from 5 to 40% of the total weight of ses041292 tavka. Casting composition according to one of Claims 1 to 6, characterized in that it contains, inter alia, at least one compound capable of reacting with regenerated isocyanate functions and thus forming a copolymer with an unsaturated polyester prepolymer. Casting composition according to claim 7, characterized in that the compound is aliphatic or aromatic glycol. Casting composition according to claim 7, characterized in that the compound is a polymer with free hydroxyl groupings selected from saturated polyesters, polyesters-amides, polyamides containing hydroxyl groupings, polyethers and polythioeters with terminal hydroxyl groupings, phenol-aldehyde resins, urea-aldehyde resins and epoxy resins. Casting composition according to claim 7, characterized in that the compound has amine functions. Casting composition according to any one of claims 1 to 10, characterized in that it contains, inter alia, at least one agent capable of forming radicals at the unblocking temperature of the blocked isocyanate. Casting composition according to any one of claims 1 to 11, characterized in that it contains at 100 wt. parts of unsaturated polyester prepolymer 50 to 300 wt. parts of ethylene unsaturated monomer, the amount of at least bifunctional isocyanate such that the molar ratio of isocyanate functions to hydroxyl functions of the unsaturated polyester prepolymer is between about 0.8 and 1.2, and the amount of blocking agent such that the molar ratio of the block functions to isocyanate functions . 13. A process for making castings from unsaturated polyester resin fillers, characterized in that the composition according to one of claims 1 to 12 is molded at a sufficient temperature and for a long enough time to regenerate the isocyanate function and form a three-dimensional network. A manufacturing process according to claim 13, characterized in that the casting time is between 0.5 and 30 minutes. Production process according to one of Claims 13 and 14, characterized in that the casting temperature is between 70 ° C and 200 ° C. Castings of unsaturated polyester resin with fillers, characterized in that they are obtained from the composition according to one of claims 1 to 12.