CS248498B1 - Cured laminate - Google Patents

Abstract

The solution concerns laminated materials for the electrical engineering sector. The essence of the solution is that the organic or inorganic reinforcement is impregnated with a hardened polyimide polymer containing a ketone in its structure, which has good temperature resistance in the range of 160—250 degrees Celsius and, when applied in laminated materials, increases mechanical and temperature stability and improves dielectric properties. Laminated materials are also advantageously used in the engineering, aviation and rocket industries.

Description

248498

The present invention provides a laminate, particularly an electrotechnical type of reinforcement made of inorganic or organic fabrics, fibers or mats, and polyimide prepolymer binders. The purpose of the invention is to obtain a technically and economically advantageous type of laminated insulating material usable at temperatures of 160 to 250 ° C.

The application of polyimide thermosetting resins to composite materials is becoming increasingly widespread due to the excellent mechanical and electroinsulating properties of prolonged thermal stress. Polyimide-based products such as glass tissue laminates, including materials clad with metal foils, mats, synthetic papers, molding and potting materials, are found in electrical engineering and electronics, but also in engineering and aerospace.

Heat curable polyirriid prepolymers, which are used either pure or modified by other additives, form a resin base of layered insulators with higher temperature resistance. The solvent of these polymers is usually an amide solvent, such as N-methyl-2-pyrrolidone, or N, N-dimethylformamide. 1-methoxyethanol (methylcellosolve) or 2-ethoxyethanol (ethylcellosolve) and other glycol ethers may also be used as a solvent for the preparation of the impregnated polyimide prepolymer solution.

A disadvantage of these solvents is that the polyimide prepolymer solution is volatile having a short shelf life. In the case of using N-methyl-2-pyrrolidine or N-N-diinethylformamide as a solvent, a high volatile content remains in the impregnated glycol ethers, mainly methoxyethanol, because of the low autoignition temperature.

General Electric BP 1 374 16 and BP 1 374 127 disclose a single-stage preparation of polyimide prepolymers in ketone solvents (without the separation of bis-maleimide intermediate in the presence of a nickel acetate and acetic anhydride catalyst. is that the polyimide oligomer obtained is difficult to wash with water in the event that acidic components remain in the product, making it impossible to prepare the laminates, in particular by clad sheet films.

The drawbacks of the prior art are solved by the invention, which is based on a layered material impregnated with a binder of polyimide prepolymer. The bismaleimide base polyimide prepolymer after curing has a 4-structure incorporated ketone of the general formula R-CO-R 1 wherein R is an aromatic or aliphatic residue of 1 to 6 C atoms in the α chain.

R 1 is an aliphatic hydrocarbon radical having from 1 to 3 carbon atoms in the chain.

The binder for laminates is prepared by known procedures by reacting bisimides with diamines in solvents or in the melt (2: 2.5: 1 mole ratio) and diamine with aromatic tetracaronic acid dianhydrides, preferably pyromellite in combination with bisimides in The formation of curable compositions is accelerated by the addition of peroxides such as benzoyl peroxide, dicumyl peroxide and the like. in an amount of 0.5 to 5% on the dry weight of the prepolymer.

If the thus prepared prepolymers precipitate in the non-solvents, for example in water, the product dried at 30 to 50 ° C is suitable as the basis for the polyimide molding materials. A prepolymer prepared in a mixed solvent of amide and non-polar liquids in a ratio of 3: 0.5 to 3: 2 is used to impregnate the reinforcement of the layered material. This ratio ensures that no biphasic system is formed or precipitated. % of a polymer whose content in the solvent is 20 to 60 wt. % dry matter. The amide component solvent is, for example, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylacetamide; N-methyl-2-pyrrolidone, dimethyl acetamide; the non-polar component is, for example, benzene, toluene or xylene, or the solvents, for example dioxane, 1,2-dimethoxyethane, dimethylsulfoxide or mixtures thereof. A combination of N-methyl-2-pyrrolidone and toluene in a ratio of 3: 2 is preferred. .

The polyimide prepolymer solution containing 20 to 60% by weight of polyimide solids is then reacted with ketone hydrocarbon R-CO-R 1 in an amount of 1 to 30% by weight. %, preferably 15 to 25 wt. %, at a temperature of 15 to 60 ° C, for 3 to 24 hours with stirring. In these conditions, the imide content of the polyimide prepolymer is increased by about 10%, the gelation time of the polyimide is reduced, and the hardening of the laminates is accelerated, increasing their temperature resistance, especially during long-term stress. In the following table, the tensile strength values during the thermal aging of polyimide fiberglass are given: 248498

Table: Bending strength limits (MPa) after thermal aging

Sample Delivered 25 ° C (MPa) 2,500 hpri 200 ° C 5,000 hpri 200 ° C 2,500 hpri 220 ° C 625 hpri 240 ° C 1. 626 389 150 192 408 2. 627 551 350 350 500 3. 608 450 320 270 517 where: the binder used is applied to the impregnation-sample 1 - fiberglass prepared from polyimide prepolymer in a solution of N-methyl-2-pyrrolidone, sample 2 - fiberglass prepared from polyimide prepolymer modified with N-methyl- 2-pyrrolidene + methyl ethyl ketone sample 3 - fiberglass prepared from polyimide prepolymer modified with epoxide in solution N-methyl-2-pyrrolidone + -i-acetone The base impregnating solution can be modified after reaction with ketones by some thermosetting plastics, for example: a) with epoxy dian resins, gram / 100 g 0.17 - 0.50 at 2 - 50% by weight on dry matter, bj with epoxy resin coatings, gram-equivalent / 100 g 0.25 - 0.60 at 2 - 50 % by weight on dry matter. with iodine bromepoxide resins, 100 g 0.17-0.50 sobsahont blades 15-25 ° / o in the amount of 2 to 50 parts by weight on the dry weight of the polyimide prepolymer. The dj combination mentioned in a, b can be further crosslinked by the addition of aromatic amine hardeners for epoxies such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone in amounts of 1 to 10 parts by weight per e) with phenolic resins of molecules, weights from 600 to 2500 in an amount of 2 to 40% of polyimide resin dry matter, fj with a mixture of phenolic and epoxide resins listed under a, b, c, e, in any ratio such that the amount thereof is from 2 to 50% by weight on the dry weight of the polyimide prepolymer.

The solution of the polyimide composition is adjusted to the necessary impregnating viscosity, depending on the resin used, from the impregnating device and the precoat conditions by adding a suitable solvent, for example N-methyl-2-pyrrolidone and toluene. A solution of the reinforcing material flow so that the evaporation of the solvents in the drying tunnel of 130 to 200 ° C is a dry matter content of 20 to 70% by weight. The dried pre-cut is cut to the appropriate size in the number required for the ridge and pressed in a press at a temperature of 160-220 ° C and a pressure of 1.5-10 MPa for 1 to 8 hours. Laminates clad with metal foils can also be made by depositing a metal foil on one or both sides of the laminate, which laminates to the surface of the material under said conditions. These clad materials are particularly suitable for multilayer PCBs at higher temperatures, for which increased dimensional stability and temperature resistance are required.

Impregnated reinforcements can also be further processed by winding, optionally by winding by extrusion on tubes, rods and profiles.

After molding, the materials are hardened to 200 DEG-300 DEG C. for 4 to 60 hours of abnormal or elevated pressure in the air or nitrogen atmosphere.

If the polyimide prepolymer is modified with phenolic or epoxy resins, when applied to laminated screeds, it increases its resistance to fire propagation.

According to the invention, the present invention allows for efficient production of an impregnating resin for the preparation of high quality laminates with increased temperature resistance of class H and good electrical and insulating properties. The preparation of prepregs with polyimide bituminous binder solves the lack of laminates with high temperature resistance and mechanical strength.

In order to concretise a given solution, the following examples of application are found in laminated materials. Example 1 To 100 g of a 40% solution of polyimide prepolymer prepared by synthesizing 2.5 mole of 4,4'-diaminodiphenylmethane bis-maleic imide with 1 mole of 4,4'-diamino diphenylmethane at 105 ° C for 4 hours in a N-solution. methyl 2-pyrrolidone and toluene (3: 2 by weight) are mixed with 15 g of acetone and after 3 hours at 25 to 30 ° C, a 48% solution of polyimide complex to impregnate the glass tissue is obtained on the dried binder content of 38-40% and after evaporation of the baffles in the drying machine of the impregnating machine at 155-160 ° C, a prepreg is obtained by compressing the laminate at 170 ° C and a pressure of 7 MPa for 2 hours followed by curing at 43 h at 200 ° C without pressure to obtain fiberglass with high mechanical properties at a working temperature of 180 degrees Celsius and 200 cc.

100 g of a 45% solution of polyimide resin was prepared by synthesizing 2.5 moles of 4,4 ' -diaminodiphenylmethane-bismalein imide with 1 mole of 4.4 ' -diaminodiphenylmethanemide at 105 DEG C. for 4 hours in a solution of N-methyl -2-pyrrolidone --- {- toluene in porosity 3: 2, with 37 g of 60% acetone disintegrating epoxy resin resin equivalent to 100 g 0.18 - 0.24 and after 3 hours of stirring at 20-25 ° C, a solution is obtained with a hard lobe of about 57% and a gelation time of 160 ° C for 6 minutes. This is used to impregnate the glass fabric treated with a dried 33% binder content. Dry for 5-10 minutes at 150-180 ° C. The non-cut leaves are laminated at 160 ° C, 7 MPa for 5 hrs of laminate and hardened 24 h / 190 ° C and 43 h // 200 ° C. After 2,500 hours of aging at 220 degrees Celsius, the laminate has a flexural strength of 300 MPa. The laminate prepared without the addition of epoxide and acetone exhibits a bending strength of only 190-200 MPa after aging.

If a binder is prepared from the binder with a 40% binder content, pressing for 3 hours at 170 ° C and curing for 24 hours at 200 ° C and 48 hours at 260 ° C in the supplied bending strength 440 MPa. After aging for 7 to 500 hours at 200 ° C, its bending strength is still 240 MPa and after 3000 hours aging at 240 ° C, the bending strength decreases to 260 MPa. Example 3

Mix 100 g of a 50% strength resin solution by condensing 2.5 moles of 4,4'-diamino-diphenylmethane bis-maleimide and 1 mole of 4,4 ' -diaminodiphenylmethane in a mixture of N-methyl-2-pyrrolidone and toluene in a porner 2: 1 with 31 gbrominated epoxy resin as an 80% solution in methyl ethyl ketone. After 34 hours, the impregnated fabric is used for impregnating the glass fabric in Example 2 and the impregnated fabric is absorbed and hardened. The laminate obtained after 2 500 hours of aging at 220 ° C achieves a bending strength of 350 MPa. The laminate prepared without the addition of epoxide and methyl ethyl ketone, under the same conditions, achieves a tensile strength of only 200 MPa. Example 4

100 g of a 45% solution of the polyimide prepolymer prepared in Example 2 with 15 g of dianepoxide resin are mixed with an epoxy equivalent of 0.17-0.25 / 100 g, 10 g acetone and 0.9 g of 4,4'-diaminodiphenylmethane apo homogenization 2 - 3 hours at room temperature gives a solution with a dry matter content of about 561% and a gelation time of 160 ° C for about 3 minutes, which impregnates a specially prepared glass tissue (aminosilanes, epoxysilanes) after the addition of 1.2 g of dicumyl peroxide. a material of 40 to 45% and after removing the solvents in a drying tunnel of a vertical machine at 150-180 ° C for 5-10 minutes, a prepreg is obtained, suitable for the preparation of copper-coated laminate by pressing for 4-6 hours priteplote 165-170 CC and for printing 4 - 6 MPa. The material has optimum properties after additional curing without pressure for 48 hours at 180 - 190 ° C. The clad material thus prepared is characterized by a dimensional stability of at least (0.0004 mm) 0.02-0.04% high temperature resistance of the soldered bath for 3 min at 270-288 degrees Celsius and is suitable for the production of printed circuit boards. Example 5

The impregnation solution is prepared by mixing 100 g of a polyimide prepolymer prepared as in Example 2 with 19 g of bromo-epoxy resin with an epoxy equivalent / 100 g of 0.18-0.24 as an 80% solution in methyl ethyl ketone and 0.6 g dicumylperoxide. The solution is diluted with N-methyl-2-pyrrolidone-1-toluene 3: 2 to give a viscosity so as to achieve a 150%, i.e. 60% -, resin build-up of the resinous bond on the glass fabric without impregnating the wiping rolls. no binder content. Upon evaporation of the solvents in the inert furnace of the impregnating machine at 140-160CC, a prepreg of a suitable sticking sheet is obtained over the self-extinguishing multilayer sheet joints into the thermally stressed devices. Example 6

A solution for impregnating the glass fabric or carbon fibers is prepared by mixing 80 g of a 50% solution of prepolymer-prepolymerized as in Example 1 with 20 g of creolelaniline formaldehyde resol (50% solution in ethanol or methanol) and after homogenization at the glass fabric is impregnated as described in Example 4. After the chopping and layering of the number of sheets required for the ridge, the dry prepreg together with the copper foil is pressed at a pressure of 4-7 MPa, at 160-170 ° C for 3 hours. The laminate obtained under cure for 48 hours at 200 ° C is characterized by a high flexural strength value measured at 200 ° C (about 70% of the measured value) and high electrical properties. In the flammability test

Claims (1)

248 9 according to IEC 707/1981 para. 9 by the FV method, the material corresponds to class V-1. EXAMPLE 7 12 g of cresol-aniline formaldehyde resin are added to 100 g of a 50% solution of polyimide prepolymer prepared by the synthesis described in Example 3 and the mixture is heated at 80 DEG C. for 10 minutes with continuous stirring. Finally, 10 g of methyl ethyl ketone are added to this solution and the glass tissue is impregnated to a dry binder content of 40-45 per cent and a prepreg is obtained after evaporation of the solvents in a dry impregnating tunnel at t = 150-165 ° C. Pressing 28 layers of prepreg at 165 ° C and 5 MPa pressure for 3 hours yields a glass laminate of about 3 mm with a durable temperature resistance of 180 ° C and excellent mechanical properties suitable for grooved glazing in external rotary machines. EXAMPLE 8 An epoxide modified polyimide binder prepared according to Example 2 is used to impregnate paper based on aromatic polyamide (Nomex) or polyester fabrics and mats, optionally cotton fabrics, to a dry binder content of 50%. After drying, the laminates are laminated at 160 DEG C., 8 MPa for 498 DEG C. for 3 hours and hardened at 200 DEG C. for 24 hours. The hardened laminate is abrasion resistant and is suitable for making lamellae for rotary compressors. EXAMPLE 9 To 100 g of a 45% solution of Kerimide 601 (manufactured by Rhone-Poulenc, France) in N-methyl-2-pyrrolidone was added 9 g of acetone and, after complete homogenization at 25 DEG C., left the solution for 24 hours. The thus prepared binder is impregnated with E 69 110 A 464 glass tissue for 50% deposition, and after drying at 170 ° C for 1.5 to 2 minutes, the chopped prepreg is compressed on a laminate at a pressure of 8 MPa and temperature. 165 CC for 3 hours. After additional hardening in the oven for 48 hours at 200 ° C, the product has a tensile strength of 540 MPa and, after exposure to 2,000 h at 240 ° C, the flexural strength is reduced to 480MPa, after 3,500 h at 240 ° C to 440 MPa. If a 45% solution of Kerimide 601 in N-methyl-2-pyrrolidone without acetone is used to impregnate the same fabric, it is necessary to raise the temperature of the drying tunnel to 180 ° C while at the same time reducing the drying time to 5 minutes. From the dried prepreg, the molded and hardened laminate having the same process has a flexural strength of 570 MPa, and after exposure for 2,000 h at 240 ° C it drops to 130 MPa and after 2,500 h at 240 ° C to 90 MPa. PRED Μ ET Cured material, in particular of an electro-insulating type, of a reinforcement of inorganic or organic fabrics, fibers or mats impregnated with a bis-maleimide-type polyimide binder, possibly with modified epoxy or phenolic resin, characterized in that the cured binder in BACKGROUND OF THE INVENTION The structure comprises 1 to 30 weight parts of an incorporated ketone R-CO-R 1, wherein R is an aromatic or aliphatic hydrocarbon radical of 1 to 6 atoms - C chain and R 1 is an aliphatic hydrocarbon radical containing 1 to 3 atoms - C in the chain.