DK141513B - Heat-resistant multicellular polyimides based on the reaction product of polymaleinimide and a nitrogen-containing monomeric compound, and process for their preparation. - Google Patents

Description

(S) (11) PUBLICATION 141513 DENMARK mlntc | S I II ° L 7I / 08 (21) Application No. 5 ^ 06/75 (22) Filed on 25 · Jul · 1975 »ffl (23) Race day 25 · Jul. 1975 \ / (44) The application presented and in accordance with the order for publication published on O. Apr. in yow THE DIRECTORY OF ____, __,. ..

PATENT AND TRADEMARKET SYSTEM W? 1 (26082j j * (71) RHONE-POULENC INDUSTRIES, 22, Avenue Montaigne, 75008 Paris, ER.

(72) Inventor Pierre Ledru, 27 rue Sala, 69ΟΟ2 Lyon, PR.

(74) Plenipotentiary in the proceedings:

The engineering company Budde, Schou & Co.

(54) Heat-resistant multicellular polyamide based on the orange polymer product and a nitrogen-containing monomeric compound and process for their preparation.

The present invention relates to heat-resistant multi-cellular polyimides on the basis of the reaction product of polymerimide and a nitrogen-containing monomeric compound and a process for their preparation.

In French Patent No. 2,220,552 it has been proposed to prepare polymers containing imide groups which are obtained by reaction of ammonia and a polymalein medium.

Furthermore, in Danish Patent Application No. 1677/75, a process has been proposed for the preparation of multicellular materials from 2 141513 a) polyimides prepared by reacting a bisimide or a mixture of bisimide and rnonoimide, whereupon these contain an olefinic unsaturation and cyclic imide groups, and an amine compound, and b) a pore-forming agent and a surfactant, this process being carried out by first preparing a granule of a partially inflated prepolymer and then curing these granules in a form under complete bloat.

Finally, it is known from French patent specification no.

1,555,564 heat and solvent resistant multicellular polyimides prepared from unsaturated bisimides with cyclic imide groups and polyamides.

The present invention relates to heat-resistant multicellular polyimides based on the reaction product of polymaleinimide and a nitrogen-containing monomeric compound, which multicellular materials are characterized in that they are produced by heating to between 90 and 250 ° C a mixture consisting of: 1) soluble prepolyimide having a softening point between 50 and 250 ° C prepared by reaction of ammonia with a polyimide of the formula / "/ C0 - c - AN 11) V CO - C - B sa wherein Y means an inert organic group under the reaction conditions with valence a, and a is a number from 2 to 4, and A and B, which may be the same or different, mean hydrogen atoms, methyl groups or chlorine atoms, the proportions of polyimide and ammonia being such that the ratio of the number of imide groups and the number of molecules of ammonia are between 2 and 100; 2) a pore-forming agent which, upon heating, decomposes under the release of a gas, and a surfactant and 3) optionally phenolic resins, epoxy resins, unsaturated polyesters, polyamidimides, polysulfones, allyl polymers or polyurethanes in amounts up to 100% by weight, based on the polymer specified in (1), and any inert fillers in amounts up to to 50% by weight, based on the polymer listed in (1), wherein the heating of the mixture is carried out until the soluble prepolyimide is converted to cured multicellular polyimides.

The present invention further relates to a process for producing these heat-resistant multicellular polyimides, characterized in that it consists of the following steps:

a) mixing in the cold of 1) a soluble, powdered prepolyimide having a softening point between 50 and 200 ° C and prepared by reacting a polyimide of the above formula and ammonia at a temperature between -30 and + 200 ° C

for a period of between a few minutes and 2 hours, the proportions of polyimide and ammonia being such that the ratio of the number of imide groups to the number of molecules of ammonia is between 2 and 100, with 2) a pore forming agent which upon heating decomposing under the release of a gas and a surfactant; and 3) optionally phenol resins, epoxy resins, unsaturated polyesters, polyamidimides, polysulfones, allyl polymers or polyurethanes in amounts of up to 100% by weight based on the prepolyimide used, and optionally inert fillers b) heating the mixture obtained under (a) to between 90 and 250 ° C for at least 5 minutes, the heating being interrupted when the soluble prepolyimide is converted to a cured multifunctional solution; cellular polyimide.

In accordance with the technique mentioned in the aforementioned French patent specification 1,555,564, the following advantages are obtained:

Multicellular materials are obtained which are comparable to those known from the aforementioned patent, but using ammonia instead of polyamines, which is economically advantageous as ammonia is a cheaper and more readily available starting material than polyamines, and partly advantageous. in regard to the health risk associated with the manufacture, since polyamines, especially the aromatic ones, exhibit various toxic effects of both loco-irritant, organ-damaging and carcinogenic.

It should be clarified that the reaction of the polyimide with ammonia leads to cured products or resins which are insoluble in conventional solvents and do not exhibit any appreciable softening below the temperature at which they begin to decompose.

However, before reaching this final state, the reaction mixture usually passes a state where a product (hereinafter called prepolymer) can be collected, whose physical and chemical properties are naturally different from those of the starting materials and which are characterized by their solubility in polar organic solvents. and by the existence of a softening point at a temperature below 250 ° C.

The reaction conditions used to prepare the prepolyimides used to prepare the multicellular polyimides of the invention can be varied within wide limits. In particular, the ammonia may be used in anhydrous gas state or in the form of an aqueous or organic solution, especially dissolved in alcohol or mixtures of water and alcohol. The polyimide can itself be used in the molten state, in the form of a solution in a polar solvent, e.g. N-methylpyrrolidone, dimethylformamide, dimethylacetamide, N-methylcaprolactam or N-acetylpyrrolidone, or in the form of a suspension in e.g. water or an organic medium such as an alcohol. According to a preferred method of operation, the ammonia is used in the form of an aqueous solution and the polyimide is used in the form of a solution or suspension. By proceeding in this way, an intimate mixture of the reactants is readily obtained. Furthermore, it is easy to dose the proportions of the reactants.

As previously stated, the proportions are of such a size that the ratio of the number of imide groups to the number of moles of ammonia is between 2: 1 and 100: 1. This ratio is preferably between 2: 1 and 10: 1.

It should be understood that when the ammonia is used in the form of a solution, its concentration is not critical. The upper limit of concentration is determined only by the solubility of ammonia in the solvent at the temperature at which the solution is prepared. As for the lower limit, this is essentially determined by practical considerations (handling as small quantities as possible of products not participating in the reaction).

The temperature of the reaction of ammonia with polyimide can be varied within wide limits, with the choice of temperature naturally affecting the residence time of the reaction mixture at the selected temperature. With the exception of the case where the polyimide is used in the molten state or where the reaction mixture must be maintained at a temperature at least equal to the melting point of the polyimide, the reaction can usually be carried out at a temperature below 200 ° C and preferably between -30 and +150. ° C depending on the nature and physical state of the reactants used. After a period of a few minutes to 2 hours, a prepolyimide whose softening point is between 50 and 250 ° C is obtained.

The conversion of the mixture on the basis of the above-described prepolyimide to a multicellular material is carried out by heating to a temperature between 90 and 250 ° C, usually between 150 and 230 ° C. The duration of this heating usually varies between a dozen minutes and 5 hours. The prepolyimide is comminuted and then thoroughly mixed with the pore forming agent and the surfactant before being subjected to the above heat treatment. The mixture takes place in the cold, ie. at a temperature of about 20 ° C, to avoid premature reaction to interfere with the homogenization of the mixture and thereby result in the production of irregular structure end products.

Advantageously, pore forming agents have a decomposition temperature at least 20 ° C above the prepolyimide softening point. Examples of such adjuvants include pore forming agents such as azodicarboxamide or the products mentioned in "Plastic Foams" by Calvin J. Benning (Vol. 2, pages 294--320). The proportion of the pore forming agent which can be varied depending on the desired density of the multicellular material is between 0.1 and 10 percent by weight of the prepolyimide.

The prepolyimide incorporates a surfactant which allows to improve the homogeneity of the cellular structure of the polymers, e.g. nonionic surfactants such as organopolysiloxanes containing polyoxyalkylene-type organic blocks. Such copolymers are e.g. described in "Plastic Foams" by Calvin J. Benning (Vol. 2, pages 320-325). Cationic surfactants such as N-alkyltrimethylenediamine dioleate or condensates of ethylene oxide and aminated coconut oil are also suitable. Anionic surfactants may also be suitable. The proportion of surfactant is 6 depending on the nature and amount of pore forming agent used.

It is usually less than 5% by weight of the prepolyimide.

Liquid or solid adjuvants may also be added to the prepolyimide in the form of powders, spheres, slats, grains, fibers or scales for the purpose of improving or modifying one or more of the finished product's properties.

In particular, the adjuvants may consist of fibers of glass, carbon, asbestos, synthetic polymers, especially polyamideimides or aromatic polyamides, or of powdery particles, e.g. may be selected from silica produced by combustion, crude finely divided silica, quartz, alumina, titanium oxide, talc, kaolin, mica, calcium carbonate, graphite, carbon black or barium sulfate.

Such adjuvants are used in amounts up to 50% by weight based on the prepolyimide.

In addition, the prepolyimide may be admixed with adjuvants which enable the hardness, mechanical properties or heat resistance of the multicellular materials to be improved. Among these auxiliaries may be mentioned especially boric anhydride which, usually used in an amount of 1-30% by weight of the polymer, increases the heat and fire resistance.

It is also possible to modify the properties of the multicellular material by incorporating resins or elastomers consisting of phenolic resins, epoxy resins, unsaturated polyesters, polyamidimides, polyurethanes, polysulfones or allyl polymers. Epoxy resins disclosed in French Patent No. 2,045,087, polysulfones disclosed in French Patent No. 2,101,79'6, polyesters disclosed in French Patent No. 2,102,878, allyl-- polymers disclosed in French Patent No. 2,094,607 or polyamidimides disclosed in French Patent No. 1,473,600.

Resins or elastomers may be incorporated in amounts up to 100% by weight, based on the weight of the polymer listed under 1).

The multicellular materials of the invention can be used in various ways: controlled bloating in a heated form, making blocks or semi-finished products, or making sheets according to the technique described in French Patent No. 2,085,391.

This patent discloses a process for the continuous production of expanded foam sheets, whereby the distribution and adjustment of the height of the liquid foam-forming mixture is effected between the coating foils prior to the expansion of the liquid and the foils simultaneously being assembled, and this method is characterized by the fact that in a length zone of 50-95% of the expansion zone for the liquid foam-forming mixture on the upper surface of the coating during the expansion itself, a continuous uniform pressure is applied which is sufficient to ensure that this upper surface remains at all times as a regular surface produced by horizontal generators. which is perpendicular to the feed direction of the foils.

It is possible to make sandwich bodies, having on one or both surfaces, e.g. by means of a polyamidimide solution, glues a film which may advantageously be made of polystyrene intermediamidimide, or a sheet of metal the thickness of which may be between 10 and 200 µm. Honeycomb structures or sheets of asbestos cement type can also be adhered to produce layered products.

Finally, the multicellular material can be subjected to heat treatment for 2-24 hours at a temperature between 180 and 300 ° C.

In this way, its mechanical properties and especially its compressive strength are increased.

The multicellular materials of the invention usually have an apparent density of between 0.03 and 0.8 g / cm and a regular cellular structure in which 80-96% of the cells are closed. They have a very high resistance to solvents and chemical agents, excellent heat and fire resistance and are self-extinguishing. The mechanical properties are satisfactory up to a density of the order of 0.1 g / cm. In order to obtain a material consisting essentially of closed cells, it is necessary that the monomers or prepolymers do not contain solvents which are volatile under the temperature conditions of expansion.

Because of these properties, the multicellular materials of the invention are of interest in several industrial fields.

In particular, they can be used for the manufacture of layered or non-layered panels intended for heat or sound insulation of high temperature areas, especially in the construction, aerospace or aerospace industries.

The invention is illustrated by the following examples.

In these examples, the compressive strength is determined by 10% deformation according to the standards ISO / TC 45 and 61 or ASTM D 695 and the fire resistance is determined according to the standard ASTM D 1692 59T.

8 T415T3

Example 1

At room temperature (21 ° C), 900 g of N, N'-4,4'-diphenylmethane-bismaleinimide are dispersed in 1098 g of dimethylformamide (DMP).

By means of a dropping funnel, 105 g of an aqueous ammonia solution with 18.2% by weight ammonia is added to the dispersion in 8 minutes. During the addition, the temperature rises to 42 ° C. Heat to 60 ° C and a clear solution is obtained within 10 minutes. It is cooled to 24 ° C over 40 minutes, and then the polymer is precipitated with vigorous stirring in 6 liters of deionized water. '

The polymer is filtered off, washed with water and dried in an oven at 50 ° C until constant weight and then under vacuum (1 mm Hg) at 80 ° C for 7 hours.

911 g of a polymer having a softening point of 140 ° C is obtained and a ratio K between the number of double bonds in the bismaleinimide and the number of ammonia molecules of 5.

After comminution, a powder having a grain size of less than 50 ° C is obtained, 100 g of the polymer prepared is mixed with 4 g of diphenyl-oxy-4,4'-disulfonylhydrazide and 1 g of a 50% methanolic solution of N -alkyltrimethylendiamin dioleate.

After homogenization, this mixture is placed in one. metal shape. It is heated in a ventilated oven to 180 ° C for 1 hour. A block is available

ISLAND

of yellow, multicellular material with a density of 0.072 g / cm. Heat for 24 hours at 200 ° C.

The color goes from yellow to light brown, but no weight loss is observed.

The material produced is non-flammable according to the standard ASTM D 1692 59 T ·.

Its compressive strength at room temperature is 4.31 kg / cm 2 in the direction of expansion of the material. At 200 ° C the compressive strength is 3.98 kg / cm 2.

Example 2

Proceed as described in Example 1, but the mixture contains 100 g of polymer 3 g of diphenyloxy-4,4'-disulfonylhydrazide 1 g of 50% methanolic solution of N-alkyltrimethylene di. amindioleat.

9 141513

A multicellular material having a density of 0.089 g / cm 3 is obtained.

The compressive strength after heat treatment is 6.08 kg / cm at room temperature and 5.02 kg / cm at 200 C.

Example 3

Proceed as described in Example 1, but the mixture contains 90 g of polymer 10 g of a polyester prepared by reaction of maleic acid, propylene glycol and allyl phthalate, 4 g of diphenyloxy-4,4, disulfonylhydrazide 1 g of 50%, methanolic solution of N-alkyltrimethylenediamine dioleate.

The polyester used is liquid, thereby promoting the dispersion of pore-forming agent and surfactant. Furthermore, it acts as a plasticizer, thereby providing a softer end product with better resistance to cracking at high temperature.

A multicellular mass with a density of 3 0.09 g / cm is obtained. The product is non-flammable according to the standard ASTM D 1692 59T.

Claims (2)

1A1513 or Patent Claims. 1. Heat-resistant multicellular polyimides based on the reaction product of polymaleinimide and a nitrogen-containing monomeric compound, characterized in that they are prepared by heating to between 90 and 250 ° C a mixture consisting of: 1. a soluble prepolyimide having a softening point between 50 and 250 ° C prepared by reaction of ammonia with a polyimide of the formula: // CO - C - A \ Y-to IV "CO - C - B 'a in which Y means an inert organic group under the reaction conditions with valence a, and a is a number from 2 to 4, and A and B, which may be the same or different, mean hydrogen atoms, methyl groups or chlorine atoms, the proportions of polyimide and ammonia being such that the ratio of the number of imide groups and the number of molecules of ammonia are between 2 and 100, 2. a pore-forming agent which, upon heating, decomposes under the release of a gas and a surfactant, and 3. optionally phenol resins, epoxy resins, unsaturated po lyesters, polyamidimides, polysulfones, allyl polymers or polyurethanes in amounts up to 100% by weight based on the polymer specified in 1) and any inert fillers in amounts up to 50% by weight based on the polymer specified in 1) heating of the mixture is done until the soluble prepolyimide is converted to cured multicellular polyimides. Process for preparing heat-resistant multicellular polyimides according to claim 1, characterized in that it consists of the following steps: a) mixing in the cold of 1) a soluble, powdered prepolyimide having a softening point between 50 and 200 ° C and prepared by reacting a polyimide having the formula and ammonia of claim 1 at a temperature between -30 and + 200 ° C for a period of between a few minutes and 2 hours, the proportions of polyimide and ammonia being such that the ratio of the number of imide groups and the number of molecules of ammonia are between 2 and 100, with 2) a pore forming agent which, upon heating,