CH445846A - Process for the production of polyimide molded articles - Google Patents

Description

  

  



  Process for the production of polyimide molded articles
The present invention relates to a process for the production of polyimide molded articles, which is characterized in that with a polyamic acid optionally present in salt form, its inherent viscosity in N, N-dimethylacetamide at 30 C and at a concentration of 0.5 g per 100 cm3 of solvent is at least 0.1, and which contains repeating pairs of amide groups that can be converted into imide groups and, if appropriate, carboxyl groups present in salt form, the number of those in the polyamic acid or

   any imide groups already present in its salt does not exceed the number of said pairs of groups which can be converted into imide groups, the said pairs of groups are converted thermally and / or chemically into imide groups after or with shaping.



   The polyamic acids are preferably derived from tetracarboxylic dianhydrides and diamines, the diamines containing a divalent group containing at least two carbon atoms and the tetracarboxylic acid dianhydrides containing a tetravalent group containing at least two carbon atoms and not more than two carbonyl groups being bonded to one carbon atom of the tetravalent group.



   The tetracarboxylic acid dianhydride radicals preferably contain a tetravalent group containing at least 6 carbon atoms and of an aromatic unsaturated nature, each of the four carbonyl groups of the dianhydride radical adhering to a separate carbon atom in the tetravalent group, while the carbonyl groups are arranged in pairs by the groups in each pair adhere to adjacent carbon atoms of the tetravalent group.



   The polyimides preferably have a repeating unit of the following structural formula: where R is the tetravalent group and R 'is a divalent group.



   The polyimides can be obtained by reacting a diamine containing at least 2 carbon atoms with a tetracarboxylic acid dianhydride which contains a tetravalent group containing at least 2 carbon atoms, with the proviso that not more than 2 carbonyl groups of the dianhydride residue on any one Carbon atom of the tetravalent group adhere to obtain a polyamic acid product, which is then given by che
EMI1.1
 mixed treatment or can be converted into a polyimide by the action of heat.



   The organic diamines which can be used for the present invention are those which correspond to the structural formula H2N-R'-NH2, wherein R 'denotes an aromatic, aliphatic, cycloaliphatic or combined aromatic-aliphatic divalent radical or substituted groups thereof containing at least 2 carbon atoms. The most suitable diamines are the primary diamines which, when reacted with a dianhydride, give polyamic acids which, after molding, can be converted into polyimides. The preferred radicals R 'in these diamines are those which contain at least 6 carbon atoms and have an aromatically unsaturated structure, such as in particular the following groups:
EMI2.1
 where R "means carbon, nitrogen, oxygen, silicon, phosphorus or sulfur.



   The diamine and the dianhydride can be reacted directly with one another. On the other hand, the dianhydride can first be mixed with a monohydric alcohol, e.g. B.



  Ethanol to react to form a diester diacid monomer, whereupon the latter is reacted with the diamine. A third variant consists in combining the two aforementioned methods.



  In all of these embodiments, the polymerization will generally be carried out under conditions such that no product with more than 50% of the polyimide is directly formed.



   According to a preferred embodiment, the polyimide will be prepared by first adding a polyamic acid with an inherent viscosity of at least 0.1, preferably 0.3-5.0, by reacting the diamine with the dianhydride in an organic, polar solvent under essentially anhydrous conditions at a temperature which is kept during the reaction below 60 ° C. and preferably below 50 ° C., and then the polyamic acid is converted into the polyimide by a heat treatment or by a chemical treatment of the type described below. The polyimide formed also has an inherent viscosity of at least 0.1, and preferably 0.3-5.0.



   The organic polar solvents that can be used to produce the polyamic acid are organic solvents whose functional groups do not react with any of the reactants (diamines or dianhydrides) to a greater extent than the reactants react with one another. In addition to being inert to the system and preferably a solvent for the product, the organic solvent must expediently be a solvent for at least one of the reactants, preferably for both reactants.

   Or to put it another way, the organic polar solvent is preferably an organic liquid that differs from both reactants and from homologues of the reactants and is a solvent for at least one of the reactants and contains functional groups that do not contain monofunctional primary and secondary amino groups and are not monofunctional dicarboxylic anhydride groups.



   It should be pointed out that, prior to the conversion stage, in the preferred embodiment it is not necessary for the polymeric components of the product to consist entirely of a polyamic acid.



  It is only necessary that the polymeric product contain at least 50 ouzo of polyamic acid, while the remainder can consist of the polyimide. If in the aforementioned method for the preparation of the polyamic acid a temperature of less than 50 ° C has been specified to achieve essentially 100 / o polyamic acid, it should be pointed out that temperatures of up to 60 ° C can be used to produce a moldable product with at least 50 ouzo polyamic acid as part of the polymeric component.

   According to the preferred embodiment, equimolecular amounts of the diamine and the dianhydride in the form of solid materials will be mixed with one another beforehand and this mixture will then be added in small proportions and with stirring to an organic polar solvent.



  By premixing the components and then adding them to the solvent in small amounts, it is relatively easy to regulate the temperature and the sequence of the operation. Since the reaction is exothermic and therefore tends to be accelerated very quickly, it is advisable to keep the reaction temperature at less than 60 ° C. by regular additions. The manner of addition can, however, be carried out in various ways. After the diamine and dianhydride have been premixed, the solvent can be stirred into the mixture. However, it is also possible to dissolve the diamine in the organic polar solvent with stirring and then to add the dianhydride slowly while controlling the reaction temperature.

   Usually, in this latter procedure, the last portion of the dianhydride will be added together with a portion of the organic polar solvent. Another method consists in adding the reactants to the solvent in small amounts, not in the form of a premix, but by adding the diamine first, then the dianhydride, then diamine, etc. In any case, it is advisable to stir or shake the polymerization system containing the solution after the additions are complete until maximum polymerization has been achieved by reaching a maximum viscosity.



   The degree of polymerization of the polyamic acid can vary. When using equimolecular amounts of the reactants under the prescribed conditions, polyamic acids of very high molecular weight are obtained. The use of any of the reactants in large excess limits the extent of the polymerization. Both the diamine and the dianhydride can be used in an excess of more than 5 ouzo, but a polyamic acid of undesirably low molecular weight will be obtained. For certain purposes, however, it may be desirable to use an excess of one or the other reactant, preferably the dianhydride, of 1-3%.



   In preparing the polyamic acid intermediate, it is essential that the molecular weight is such that the inherent viscosity of the polymer is at least 0.1, and preferably 0.3-5.0. The inherent viscosity is measured at 30 C and a concentration of 0.5 g of the polymer in N, N dimethylacetamide. In order to calculate the inherent viscosity, the viscosity of the polymer solution is measured in relation to the viscosity of the solvent alone.
EMI3.1





   <SEP> viscosity <SEP> of the <SEP> solution
<tb> nat rl <SEP> logarithm
<tb> <SEP> Viscosity <SEP> of the <SEP> solvent
<tb> Logarithmic <SEP> viscosity number
<tb> C
<tb> where C is the concentration, expressed as grams of polymer per 100 cm3 of solvent. It is known that the inherent viscosity of polymeric products is directly related to the molecular weight of the polymer.



   The amount of organic polar solvent used in the preferred embodiment need only be sufficient to dissolve the diamine and, together with the polymeric component ultimately dissolved therein, to provide a sufficiently low viscosity for converting the materials into molded articles. It has been found that it is most expedient to use a solvent which makes up at least 60 / o of the final polymeric solution, so that the solution should contain 0.0540 / o of the polymeric component.

   The viscous solution of the polymeric mass, which contains at least 50 ouzo polyamic acid in the polymeric component, dissolved in the organic polar solvent, can be used as such for the formation of shaped objects.



   The molded articles which contain at least 50 / o polyamic acid are then converted into the corresponding polyimide molded articles. It should be understood that the methods described here can also be applied to compositions which contain at least 50 ouzo of the salt derivatives of polyamic acids, e.g. B. the triethylammonium salt of poly amic acids, instead of the polyamic acids.



   One embodiment for the production of the polyimides consists in that polyamic acids with repeating units of the following structural formula:
EMI3.2
   where> isomers means heating heating above 50 C treated. This heating converts pairs of amide and carboxylic acid groups into imide groups. The heating can take anywhere from a few seconds to several hours.



  In general, it is desirable to gradually increase the temperature up to the transition temperature in order to reduce the formation of voids and bubbles within the polyimides due to the formation of water vapor and also to avoid crystallization or embrittlement. t) In addition, it was found that it is expedient to heat the polyimide to a temperature of 300-500 ° C. for a short time (15 seconds to 2 minutes) after the conversion of the polyamic acid into the polyimide by the heating process described above, whereby an improved thermal and hydrolytic resistance of the polyimide is guaranteed.



   Another method of converting the polyamic acid composition into the corresponding polyimide consists in treating the former composition with a mixture of acetic anhydride and pyridine. The polyamic acid molded article can be treated in a bath containing acetic anhydride and pyridine. The acetic anhydride to pyridine ratio can vary from just a little over zero to unlimited mixtures. It is assumed that the pyridine acts as a catalyst for the action of the cyclizing agent, namely acetic anhydride.



   A third variant for converting the polyamic acid composition into the polyimide is that the treatment with a carbodiimide, e.g. B. dicyclohexylcarbo-diimide. The carbo-diimide serves to dehydrate the polyamic acid to form the polyimide, serving as an effective cyclizing agent.



   A fourth method is that these treatments can be used in combination. For example, the polyamic acid can be partially converted into the polyimide by chemical treatment and the cyclization to the polyimide can then be completed by subsequent heat treatment. If it is desired to mold the mass into suitable shapes, the conversion of the polyamic acid to the polyimide in the first stage should be 50 / o. After molding, the cyclization of the polyimide / polyamic acid can be completed.



   The presence of polyimides is indicated by their insolubility in cold, basic reactants, which is in stark contrast to the good solubility of the polyamic acid. The presence of the polyimide can also be determined by the infrared spectra of the polyamic acids. The spectra initially show a predominant absorption band at around 3.1 microns, due to the NH bond. This band gradually disappears, and as the reaction increases, the polyimide absorption band, a doublet, can be found at about 5, 64 and 5, 89 microns. After the conversion has ended, the characteristic polyimide band prevails.



   Among the diamines suitable for the present invention are:
4,4'-diamino-diphenyl-propane;
4,4'-diamino-diphenyl methane;
Benzidine;
3,3'-dichlorobenzidine;
4,4'-diamino-diphenyl sulfide;
3,3'-diamino-diphenyl sulfone;
4,4'-diamino-diphenyl sulfone;
4,4'-diamino-diphenyl ether;
1,5-diaminonaphthalene; meta-phenylenediamine; para-phenylenediamine;
3, 3'-dimethyl-4, 4'-biphenyl-diamine;
3,3'-dimethoxybenzidine;
2,4-bis (amino-t-butyl) toluene; Bis (para-ss-amino-t-butyl-phenyl) ether; Bis (para / 3-methyl-A-aminopentyl) benzene; Bis-para- (1,1-dimethyl-5-aminopentyl) -benzene;
1-isopropyl-2,4-metaphenylenediamine; m-xylylol-diamine; p-xylyl-diamine;

       Di (para-aminocyclohexyl) methane;
Hexamethylene diamine;
Heptamethylene diamine;
Octamethylene diamine;
Nonamethylene diamine; Decamethylene diamine; Diamino-propyl-tetramethylene-diamine;
3-methyl-heptamethylene-diamine;
4,4-dimethyl-heptamethylene-diamine;
2, 11-diaminododecane; 1,2-bis (3-aminopropoxyethane);
2,2-dimethyl-propylenediamine; 3-methoxy-hexamethylene diamine;
2,5-dimethyl-hexamethylene-diamine;
2,5-dimethyl-heptamethylene-diamine;
3-methyl-heptamethylene-diamine; 5-methyl-nonamethylene-diamine;
2, 1 l-diamino-dodecane;
2, 17-diamino-eicosadecane; 1,4-diamino-cyclohexane;

      1, 1 Q-diamino-1, 10-dimethyl-decane;
1, 12-diamino-octadecane;
H. (CH2) SO (CH2) O (CH2) 3 NH2;
H2N (CH2) 3S (CH2) 3NH2;
H2N (CH2) 3N (CH3) (CH2) 3NH2;
Piperazine.



   The tetracarboxylic acid dianhydrides useful for the present invention correspond to the following formula:
EMI4.1
 wherein R is a tetravalent radical, e.g. B. means an aromatic, aliphatic, cycloaliphatic or a com-bin aromatic and aliphatic radical or substituted derivatives thereof.

   The preferred dianhydrides are, as mentioned above, those in which the radical R has at least 6 carbon atoms and is of an aromatically unsaturated nature, each of the 4 carbonyl groups of the dianhydride being attached to a separate carbon atom in the tetravalent radical and the carbonyl groups being arranged in pairs, the groups in each pair being attached to adjacent carbon atoms of the radical R to form a five-membered ring of the following type:
EMI4.2
 Thus, the following dianhydrides are suitable for the present invention:

      Pyromellitic acid dianhydride;
2, 3, 6, 7-naphthalene-tetracarboxylic acid dianhydride;
3, 3 ', 4, 4'-diphenyl-tetracarboxylic acid dianhydride;
1, 2, 5, 6-naphthalene-tetracarboxylic acid dianhydride;
2, 2 ', 3, 3'-diphenyl-tetracarboxylic acid dianhydride;
2,2-bis (3, 4-dicarboxyphenyl) propane dianhydride;
Bis (3, 4-dicarboxyphenyl) sulfonic dianhydride;
Perylene, 3, 4, 9, 10-tetracarboxylic acid dianhydride;
Bis (3, 4-dicarboxyphenyl) ether dianhydride; Bis (3, 4-dicarboxyphenyl) sulfonic dianhydride and sithylene tetracarboxylic acid dianhydride.



   The solvents suitable for the synthesis of the polyamic acid compositions used as starting materials for the preferred production process for the polyimides are the organic polar solvents with a dipole moment, the functional groups of which do not react with the diamines or the dianhydrides.



  The organic polar solvent should in general not only be inert with respect to the system and act as a solvent with respect to the product, but it should also be a solvent for at least one of the reactants and preferably for both. Solvents from the class N, N-dialkylcarboxylamides are suitable as solvents, the low molecular weight solvents from this class, and in particular N, N-dimethylformamide and N, N-pimethylacetamide, being preferred. These solvents can be easily removed from the polyamic acid and molded polyamic acid articles by evaporation, displacement, or diffusion.

   Other typical compounds of this class of solvents are N, N-DiÏthylformamid, N, N-DiÏthylacetamid, N, N-Dimethylmethoxy- acetamide, etc. Other organic polar solvents which can be used for the present process are dimethyl sulfoxide, N-methyl-2-pyrrolidone, pyridine, dimethyl sulfone , Hexamethylphosphoramide, tetramethylene sulfone, dimethyltetramethylene sulfone. The solvents can be used alone or in conjunction with solvents or in combination with non-solvents, such as. B.



  Benzene, benzonitrile, dioxane, butyrolactone, xylene, toluene and cyclohexane can be used. The addition of water cannot be used. It is necessary that the process is carried out in a practically anhydrous state.



   The present invention will be explained in more detail by the examples given below.



  However, these examples are not intended to be limiting in nature.



   The following abbreviations are used for reasons of convenience. So means
DDP = 4,4'-diamino-diphenyl-propane;
DDM = 4,4'-diamino-diphenyl methane; pp = benzidine;
POP = 4,4'-diamino-diphenyl ether;
PSP = 4,4'-diamino-diphenyl sulfide; PSOP = 4,4'-diamino-diphenyl sulfone;
PMDA = pyromellitic acid dianhydride;
PPDA = 2, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride;
PEDA = bis (3, 4-dicarboxyphenyl) ether dianhydride;
DMF = N, N-dimethylformamide;
DMA = N, N-dimethylacetamide;

      P = pyridine;
AA = acetic anhydride;
MPD = meta-phenylenediamine;
PPD = para-phenylenediamine;
B = butyrolactone;
HMD = hexamethylenediamine, and
DMHMD = 4,4'-dimethyl-heptamethylene-diamine
The examples are compiled in Table I.



  The details of the examples in which some of the masses turned into objects such as B. films, threads and foils have been deformed, follow the table.



   The preparation of some key ingredients used in these examples are given below.



   The pyromellitic acid dianhydride used is obtained in the form of white crystals by sublimation of the commercial product through silicon dioxide gel at 220-240 ° C. and 0.25-1 mm mercury pressure.



   N, N-Dimethylformamide and N, N-dimethylacetamide are obtained by fractional distillation from phosphorus pentoxide, the fraction distilling at 47.5 ° C. and 17 mm pressure being N, N-dimethylformamide, while the fraction distilling at 73 ° C. and 30 mm pressure rende fraction consists of N, N-dimethylacetamide.



   Table I.
Summary of the examples
Reaction partner in g
Example diamine dianhydride cm3 solvent method of conversion
1 20, 0 DDM 22, 0 PMDA 200 DMF heat
2 10, 35 DDP 10, 0 PMDA 60 DMF / P (1/1) heat
3 3, 0 DDM 3, 3 PMDA 50 DMF heat
4 9, 15 POP 10, 0 PMDA 100 DMF / P (3/2) heat 5 9, 38 PSP 10, 0 PMDA 130 DMF / P (1/1) heat
6 5, 17 DDP 10, 1 PMDA 75 DMFiP (3/2) heat
4, 22 pp
7 * 10, 35 DDP 10, 0 PMDA 50 DMF heat
8 * 3, 0 DDM 3, 3 PMDA 50 DMF heat
9 10, 35 DDP 10, 0 PMDA 56 DMF ** 10 11, 2 PSO.

   P 10, 0 PMDA 75 DMF / P (2/1) ** 11 2, 01 PP 2, 37 PMDA 50 DMF P / AA 12 5, 17 DDP 10, 1 PMDA 75 DMF / P (3/2) P / AA 4, 22 PP 13 11, 2 PSO2P 10, 0 PMDA 150 DMF P / AA 14 9, 8 PSP 10, 0 PMDA 180 DMF P / AA 15 1, 30 POP 2, 18 PPDA 30 P16 80, 0 POP 87, 1 PMDA 464 DMA heat 17 12, 0 POP 13, 0 PMDA 191 DMA heat 18 0, 7 POP 1, 09 PEDA 25 DMA heat * In Examples 7-8, 50 molto of the polyamide-acid solutions were added to reduce 30 molto the acid groups in the polyamide-acid solution converted into the tri-polyamide-acid groups in the corresponding polyimide ethylammonium salt.

   before the final conversion by ** In Examples 9 and 10 stoichiomic heating and heating took place, respectively. trical amounts of acetic anhydride and pyridine
Composition of the examples
Reaction partner in g Example diamine dianhydride cms solvent Method of conversion 19 12, 4 MPD 25, 0 PMDA 145 DMF warm 20 6, 2 MPD 25, 0 PMDA 200 DMF / P (1/1) warm
6, 2 PPD 21 12, 4 MPD 25, 0 PMDA 175 DMF / P (4/3) * 22 6, 2 PPD 12, 5 PMDA 120 DMA P / AA 23 12, 4 MPD 25, 0 PMDA 145 DMF P / AA 24 12, 4 MPD 10, 0 PMDA 200 DMF / B (4/1) P / AA polyamide-acid formation conversion stage,

   Example reactants solvents chemicals used 25 MPD PMDA DMA AA / P 26 PP PMDA DMF AA / P / Benzene 27 ** DDP PMDA DMF AA / P 28 ** MPD PMDA DMF AAiP
PPD 29 ** MPD PMDA DMA AA / P / cyclohexane 30 ** MPD PMDA DMA AA / P / acetonitrile
Example 1
20.0 g (0.11 mol) of 4,4'-diamino-diphenylmethane are dissolved in 150 cm3 of dimethylformamide. 22.00 g (0.11 mol) of pyromellitic acid dianhydride are then added in portions with stirring or shaking, the solution being cooled from the outside to about 15 ° C. using running water. The viscous material is further diluted with 50 cm 3 of dimethylformamide in order to obtain a casting solution containing 18.1% by weight of the polyamic acid.

   The inherent viscosity is 1.73 (0.5% solution in dimethylformamide).



   Then, with the aid of a doctor blade, foils are poured through an opening of about 0.38 mm and they are dried for 15 minutes at 120 ° C. in an oven in a vigorous, dry stream of nitrogen. The foils are then attached to steel plates with magnets, additionally dried for 15 minutes at 120 ° C. in a nitrogen atmosphere and then heated to 300 ° C. in a hot vacuum oven in order to convert the polyamic acid into the polyimide.

   The polyimide film removed had the following properties: Logarithmic viscosity number 0.9 (0.5% solution in sulfuric acid) Density = 1.362 Polyamide acid formation Conversion stage Examples of reactants Solvents chemicals used 31 ** MPD PMDA DMA AA / P / chloroform 32 ** MPD PMDA DMA AA / P / Benzene 33 ** MPD PMDA DMA AA / P 34 ** MPD PMDA DMA AA / P / carbon tetrachloride 35 MPD PMDA DMA AA / P / Benzene
PP * In example 21, stoichiometric amounts of acetic anhydride / pyridine were added to the polyamide-acid solutions,

   in order to convert 30 mol / o polyamide-acid groups into the corresponding polyimide by heating before the last conversion stage.



   ** In these examples, the acid groups in the polyamide acid were converted into the triethylammonium salt.



   Table 1 (continued)
Composition of the examples polyamide-acid formation conversion stage, examples reactants solvents chemicals used 36 MPD PMDA DMF AA / tetramethylene sulfone
DDM 37 PSP PMDA DMF AA / P / Cyclohexane 38 PSO2P PMDA DMF AA / P / Cyclohexane 39 MPD PMDA DMA / P AA 40 DDM PMDA DMA / P AA 41 DDM PMDA DMA / AA AA / P / ¯thyl acetate 42 POP PMDA DMA / P AA 43 PSP PMDA P AA 44 PSP PMDA DMA / P AA 45 PPD PMDA DMA AA / P 46 MPD PMDA DMF AA / P 47 PP PMDA DMF AA / P 48 DDP PMDA DMF / P AA / P
PP 49 PSO2P PMDA DMF AA / P 50 PSP PMDA DMF AA / P 51 HMD PMDA DMA AA / P / Benzene 52 DMHMD PMDA DMA AA / P / Benzene Initial modulus at 23 C = 24 608 <RTI

   ID = 6.28> kg / cm2 at 200 C = 12 655 kg / cm2 elongation at 23 C = 14 / o at 200 C = 22% tensile strength at 23 C = 837 kg / cm2 at 200 C = 499 kg / cm2 impact strength = 2 .01 kg / cm / 0, 025 mm thickness tear strength = 4, 9 g / 5, 08 cm crack / 0,

   025 mm thickness Retains toughness grade-13. 600 Hydrolytic stability - longer than 100 hours in boiling water
24 hours in steam thermal stability-longer than 90 hours at 250 C in air more than 24 hours at 310 C in air zero tear strength- temperature-785 C electrical properties spec.

   Resistance (ohm. Cm) at 23 C-higher than
2.5 X 1015 at 250 C-higher than
4, 1 X 1011 dielectric constant (K) dielectric loss factor (Df) Temp. F K Df 23 C 102 3, 96 0, 0044 23 C 105 3, 86 0, 0086 250 C 102 3, 19 0, 0109 250 C 105 3 , 17 0, 0019
The above tests were carried out as follows.



      Tensile strength, elongation and initial modulus (Young's modulus): The measurements were carried out at 23 C and 50 ouzo relative humidity. For this purpose, the film was stretched in the form of samples, which were produced with a Thwing-Albert cutting tool, with a width of 6.35 mm at a rate of 100 / o per minute until the sample broke. The force applied at the moment of the break in kg / cm2 corresponds to the tensile strength. The elongation corresponds to the percentage increase in length of a sample at break.



  The initial modulus (Young's modulus) in kg / cm2 is directly related to the film stiffness. It is obtained from the slope of the stress curve at an elongation of 1 / o. Both the tensile strength and the initial modulus are related to the initial cross-section of the sample.



   Zero tear strength temperature: This temperature is the temperature at which a film can withstand a load of 1.4 kg / cm2 cross-sectional area of the film for no more and no less than 50.5 seconds. The test is carried out by bringing the sample into contact with a heated rod, applying the correct load beforehand, and measuring the time it takes to break. This test is carried out at different temperatures until the so-called zero tensile strength temperature is determined.



   The toughness level is determined by creasing a 0.0254-0.178 millimeter thick film several times by folding and creasing the film by 180, then creasing it by 360 and creasing to complete a cycle. The number of wrinkling cycles that the film is able to withstand before tearing at the wrinkled point is referred to below as the degree of toughness or degree of toughness. If a film cannot be creased without tearing, it has a degree of toughness of zero, while in those cases in which the film tears in the second cycle, the degree of toughness is 1, etc.

   The degree of toughness for films produced according to the invention must be at least 3.



     Toughness Retention: This test is used to determine the effect of heat treatment on toughness retention. For this purpose, the polymer is heated to 360 ° C. for 20 minutes in a nitrogen atmosphere and the loss of toughness caused by this heating process is measured. The retention of the toughness grade must also be at least 3.



   The impact strength or pneumatic impact strength is the energy required to tear a film, which is expressed in kg-cm / 0.025 mm thickness of the film sample. It is determined by measuring the speed of a ball with a diameter of 12.7 mm and a weight of 8.3 g, which has been subjected to mechanical acceleration by means of air pressure, first in free flight and then when a film sample of 44.5 is torn X 44.5mm obstructed flight. The velocities are measured by photoelectrically measuring the passage of the steel balls between two light beams which are arranged at a certain distance from each other.

   Pneumatic impact resistance is measured by the loss of kinetic energy due to the tearing of the film sample and is calculated by subtracting the square of the speed in obstructed flight from the square of the speed in free flight and the result with the weight of the projectile divided by the the acceleration generated by gravity, multiplied. This test is carried out at 23 degrees Celsius and a relative humidity of 50 ouzo, with the test samples being conditioned for 24 hours at 23 degrees Celsius and a relative humidity of 50 I / o.



   The tear strength is measured with an Elmendorf test apparatus. A film is cut into strips of 63.5 X 127.0 mm. Ten such strips cut out from each direction, i.e. H. ten strips, the longer dimension of which is in the direction of ejection, casting or calendering of the film, and ten strips, the longer dimension of which is in the cross-machine direction, are tested at 23.9 ° C and a relative humidity of 35%. The test apparatus consists of a fixed jaw or claw and a movable jaw or claw which are arranged on a pendulum which oscillates in a substantially frictionless bearing which is equipped with means for measuring the maximum deflection of the pendulum oscillation.

   After the specimen has been clamped in the test apparatus, an initial cut of 20.6 mm, which runs in the intended direction of the subsequent tear, is made with the aid of a blade arranged on the test apparatus. The force required to expand the initial tear is measured by measuring the work done in tearing the film over a given distance of 50.8 mm. The work is measured on the basis of the difference between the oscillation of a pendulum, first in the free state and then in the state hindered by the tearing of the film. Additional weights can be attached to the pendulum if the tear strength of a single sheet of film exceeds the capacity of the pendulum alone.

   The scale of the Elmendorf test device, a device customary in the paper industry, is read off as grams / 50.8 mm tear per 16 sheets. Since only 10 sheets are used in the present case, the values obtained with this test device must be corrected and then converted into grams / 50.8 mm crack / 0.025 mm thickness.



   The hydrolytic and thermal resistances result from the above description of the results.



   The electrical properties are determined as described in US Pat. No. 2,787,603.



   Examples 2-10
These examples are carried out in essentially the same manner as Example 1, using the ingredients shown in Table I.



  It should be noted that, for Examples 7 and 8, 50 M01 ío of the acid groups in the polyamic acid solution were converted into the triethylammonium salt.



  The cast films are converted into the polyimide films by first heating them to 120 ° C. and then to 300 ° C. as described in Example 1. In Examples 9 and 10, a two-stage conversion method was used in accordance with the information in Table I.



   The properties of the polyimide films obtained are shown in Table II below.



   Table II
EMI8.1


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Examples 11-14
The polyamic acid solutions were prepared in essentially the same manner as in Example 1 using the ingredients shown in Table I.



  The solutions were poured with the doctor blade with the same opening as indicated above. After drying for 15 minutes under dry nitrogen in an oven with forced circulation of the gas, the polyamic acid sheets were stripped from the glass plates and chemically converted into polyimide sheets.



   In Example 11, the film was treated in a mixture of benzene, pyridine and acetic anhydride (mixing ratio 2: 2: 1) for 20 hours in order to effect its conversion into the polyimide. The film was then dried at 180 ° C. for 2 hours and then heated to 500 ° C. for 1 minute.



   In Examples 12-14, the films were treated in a mixture of cyclohexane, pyridine and acetic anhydride (mixing ratio 15: 1: 1) for 24 hours, then extracted in dioxane for 1 hour and finally at 130 ° C. for 1 hour. dries.



   The properties of the films obtained are given in Table III below.



   Table 777
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Example 15
This example is carried out in practically the same way as Example 1 using the components given in Table I. It should be noted that 2.18 g of 2, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride were used.



   A polyimide film was produced in the same manner as in Example 1. A tough film was obtained with properties similar to those given in Table II, the degree of toughness being retained being greater than three.



   Example 16
80,000 g (0.3996 mol) of bis (p-aminophenyl) ether and 87.137 g (0.3996 mol) pyromellitic acid dianhydride are introduced into a 2000 cm3 three-necked flask.



  473 g of N, N-dimethylacetamide and 473 g of toluene are then added and the mixture is kept in a nitrogen atmosphere with stirring for 4 hours. A very viscous solution is obtained. 48.5 g of this polyamic acid solution are diluted with 23 g of N, N-dimethylacetamide and 5.46 g of titanium dioxide in the form of rutile are dispersed in this solution. The pigmented polyamic acid is deposited over a copper substrate and converted into the insoluble polyimide by means of heat. The film is then placed in an oven at 100 ° C. and the temperature is increased to 370 ° C. over 35 minutes. The film obtained has excellent adhesive properties on samples, such as. B. sharp bending, convex and concave impact, and cellophane film test.



   Example 17
12,000 g (0.055 mol) of bis (p-aminophenyl) ether and 13.02 g (0.055 mol) of pyromellitic acid dianhydride are introduced into a 500 cms three-necked flask.



  183 g of N, N-dimethylacetamide are then added and the mixture is kept in a nitrogen atmosphere and stirred for 5 hours. A viscous solution is obtained. The polyamic acid solution is diluted to 11 / o solid materials by adding 20 g of N, N-dimethylacetamide. The inherent viscosity of the polyamic acid by dilution to 0.5 ouzo solid materials in N, N-dimethylacetamide is 1.1.



   This polyamic acid solution (11% solid materials) is applied to a copper wire with a coating nozzle and the wire provided with the coating is passed vertically through an oven (1.22 m high). The furnace temperature is 150 C at the bottom and 370 C at the top, while the wire speed is 2.44-3.05 m per minute. As it passes through the oven, the polyamic acid is thermally converted into polyimide. Ten such coatings are applied to obtain a polyimide coating 0.0457-0.0483 mm in diameter.

   This gives a flexible, non-fragile coating
The properties of this polyimide-coated wire are as follows, using the methods according to US Pat. No. 2,787,603, column 4, lines 53 et seq .: dielectric strength = 3400 volts per 0.025 mm insulation resistance = infinite transit temperature = 485 C dielectric constant (100 hertz) = 3.78 dielectric loss factor (100 hertz) = 0.0029
This material resists common organic solvents, such as. B. hexane, ethyl acetate, acetone, xylene, NN-dimethylacetamide, ethanol, chloroform, and dilute acids, such as.

   B. 50% hydrochloric acid and sulfuric acid, but the coating is attacked by a 1 /% aqueous potassium hydroxide solution.



   Accelerated tests for determining the life of the insulation at elevated temperatures in the range of 220-280 C were performed and plotted against time versus temperature. It was found that this insulation is excellently suited for electrical equipment of class H, provided the line obtained is extrapolated for the temperatures which correspond to the corresponding insulation classes, as defined in A.I.E.E, Test No. 57.



   Example 18
A mixture of 1.0894 g (0.00351 mol) of bis (3, 4-dicarboxyphenyl) ether dianhydride (m.p. 230 to 233 C) and 0.7037 g (0.00351 mol) of 4,4'-diamino Diphenyl ether is mixed with 25 cm3 of N, N-dimethylacetamide. On stirring, the monomers dissolve to form a colorless, slightly viscous solution with an inherent viscosity in 0.5 / o N, N-dimethylacetamide of 0.74.



   Polyamic acid thin films were made by pouring samples of the polyamic acid solution onto a glass plate and allowing the solvent to evaporate in a nitrogen atmosphere. The polyamic acid films were then converted into polyimide films in the heat by heating them in a glass tube. The polyamic acid films were slowly heated in a stream of nitrogen to 325 ° C. for about 5 hours.

   The films thus obtained were transparent, pale yellow and had a degree of toughness of more than 3 and the following properties:
Tack temperature (in English referred to as embroidery temperature p) = approx. 305 C Tensile strength = 1160 kg / cm2 Elongation = 22 / o Initial module at room temperature = 52 449 kg / cm = dielectric constant = 3.81 Dielectric loss factor = 0.0012
Example 19
12.4 g (0.115 mol) of m-phenylenediamine are dissolved in 75 cm3 of dimethylformamide. 25.00 g (0.115 mol) of pyromellitic acid dianhydride are then added in portions to this solution with external cooling by means of running water at about 15 ° C.

   The last portion of dianhydride is added in 10 cm3 of dimethyl fortnamide.



  A viscous material is obtained which is further diluted with 16 cm3 of dimethylformamide and then filtered through a pressure filter.



   From this, foils are poured onto glass plates and dried in vacuo for 30 minutes at 80 C.



  After being stripped from the plates, the films are fixed on a steel plate by means of magnets, with the edges held down. The whole thing is then dried in a vacuum for 30 minutes at 100-110 Celsius. The plate with the film is then heated in a hot vacuum oven to 300 ° C. for 15 minutes in order to convert the polyamic acid into the polyimide.

   The removed polyimide films have the following properties: Logarithmic viscosity number = 0.33 (0.5% solution in
Sulfuric acid) density = 1. 43 initial modulus = 28123 kg / cm2 elongation = 10 / o tensile strength = 1055 kg / cm2 maintaining the degree of toughness greater than 3 hydrolytic = 100 hours in boiling water resistance,

  
18 hours in steam at 180 C Thermal resistance = longer than 30 days at 300 C in air Zero tear resistance temperature = 800 C Electrical spec. Resistance (ohm-cm) at 23 C greater than 105 Examples 20-21
These examples are carried out in practically the same way as in Example 19, the constituents mentioned in Table I being used. All cast films are converted into polyimide films by heating to 100 to 110 ° C. and then to 300 ° C. in the manner described in Example 19.

   In Example 21, a two-stage conversion method according to the information in Table I is used.



   The properties of the polyimide films obtained are shown in Table IV below.



   Table IV
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The polyamic acid solutions are prepared in essentially the same manner as in Example 25 using the ingredients shown in Table I. The solutions are cast into films on glass plates.

   After drying for 30 minutes, the polyamic acid films are stripped off the glass plates and chemically converted into polyimide films.



   In Example 28, the film is treated in a mixture of pyridine and acetic anhydride (mixing ratio 3: 2) for 24 hours in order to bring about the conversion into the polyimide. The film is then immersed in dioxane for 2 hours, dried at 130 ° C. for 1 hour and then heated to 380 ° C. for 1 minute.



   In Examples 29 and 30, the films are treated in a mixture of cyclohexane, pyridine and acetic anhydride (mixing ratio 15: 1: 1) for 48 hours, then extracted in dioxane for 1 hour and finally dried at 120 ° C. for 1 hour.



   The properties of the films obtained are shown in Table V below:
Table V
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Example 25
6.2 g of m-phenylenediamine are dissolved in 50 cm3 of dimethylacetamide. The solution is cooled to about 15 C with a water jacket. Then 12.5 g of pyromellitic acid dianhydride are stirred in in portions.



  25 cm 3 of dimethylacetamide are added in order to obtain a polyamic acid solution which contains 20.8% by weight of polymer. Films are then cast using a doctor blade with an opening of 0.254 mm and dried at 120-130 ° C. for 30 minutes The inherent viscosity of the polymer solution, in a 0.5 "/ c. igen solution of DMA, is 0.91.



   The film is soaked overnight in a mixture of 180 cm3 benzene, 120 cm3 pyridine and 50 cm3 acetic anhydride. The film is then dried in vacuo at 160 ° C. for 2 hours, a strong, tough, flexible film being obtained.



  Infrared spectra can be used to determine that it is a polyimide film.



   Example 26
16.9 g of benzidine are dissolved in 100 cm3 of dimethylformamide. Then 20.0 g of pyromellitic dianhydride are stirred in in portions and the whole thing is cooled to about 15 ° C. using a water jacket.



  This forms a viscous solution which is diluted by adding 150 cm3 of DMF to obtain a polyamic acid solution which contains 13.5% by weight of polymer. The inherent viscosity is 1.8 if it is measured in a 0.5% solution of DMF. The polymer solution is poured into foils with a doctor blade with an opening of 0.381 mm and dried at 120 ° C. for 20 minutes. The films are for at least 20 hours in a mixture of 230 cm3 benzene, 200 cm3 pyridine and
100 cm3 of acetic anhydride soaked. These foils are then dried in a vacuum for 2 hours at 180 ° C, giving tough, flexible polyamide foils.



   Example 27
10.35 g of 4,4'-diamino-diphenylpropane and 10.0 g of pyromellitic acid dianhydride are weighed into a beaker and mixed. The solid mixture is stirred into 75 cm3 of dimethylformamide while cooling with the aid of a water jacket at about 11 ° C. After the solid constituents have dissolved, the solvent solution has an inherent viscosity, measured in a 0.5% solution of DMA, of 0.74. The polyamic acid solution thus obtained is diluted with 50 cm3 of dimethylformamide and then treated with 5.5 cm3 of triethylamine.



   A sample of this solution, which contains triethylamine, is poured into a mixture of 50 cm3 acetic anhydride and 120 cm3 pyridine in a Waring mixer and the whole is stirred for 30 minutes. A yellow precipitate is obtained. The conversion appears to be over after 5 minutes. The precipitate is filtered off, washed with benzene and dried in vacuo at 120 ° C. for 2 hours. The infrared spectra of the powder show that it is a polyimide powder.



   Example 28
8.7 g of m-phenylenediamine, 3.7 g of p-phenylenediamine and 25.0 g of pyromellitic acid dianhydride are weighed into a flask and mixed. The solid mixture is stirred into 100 cm3 of dimethylformamide in portions, the solution being cooled to about 15 C with the aid of a water jacket. The last portion is added together with 50 cm3 of dimethylformamide, a polyamide acid solution containing 20.6% by weight of polymer being obtained. The logarithmic viscosity number, measured in a 0.5% solution of DMA, is 1.5.



   110 g of this polymer solution are mixed with 9.5 cm3 of triethylamine and 50 cm3 of dimethylformamide.



  The polymer begins to precipitate, after which 4.5 cm3 of acetic anhydride and 7.5 cm3 of pyridine and 10 cm3 of acetic acid are added to this mixture, giving a yellow, viscous solution after stirring briefly.



  Part of this polyamide acid solution is poured with a doctor blade at an opening of 0.254 mm and dried for 15 minutes at 120-130 ° C. The films are converted into the corresponding polyimide by soaking them in a copious excess of a mixture of pyridine and acetic anhydride (volume ratio of 3: 2) for 12 hours. After the films have been dried for 1 hour at 130 ° C., they are heated to 250 ° C. for 1 hour in vacuo. The films are then subjected to a heat treatment in air at 380 C for 5 minutes, tough, flexible films being obtained.



   Examples 29-32
6.2 g of m-phenylenediamine and 12.5 g of pyromellitic acid dianhydride are weighed into a flask and mixed. The mixture is then stirred in portions into 50 cm3 of dimethylacetamide while cooling to about 15 Celsius. 10 cm3 of dimethylacetamide are added to the last portion, a viscous polyamic acid solution being obtained. 8 cm3 of triethylamine are added together with 15 cm3 of dimethylacetamide, a solution of the triethylamine salt of the polymer being obtained. With the aid of a doctor blade with an opening of 0.254 mm, films are cast, which are dried for 15 minutes in an air circulation oven at 120 Celsius.



   These foils are soaked in a bath consisting of 30 cm3 of pyridine, 30 cm3 of acetic anhydride plus 450 cm3 of solvent. The solvent in these cases was as follows, namely for example 29 cyclohexane, for example 30 acetonitrile, for example 31 chloroform and for example 32 benzene. The completion of the conversion is checked by heating the foil to 400 ° C. in an oven. The films are extracted with dioxane and dried for 1 hour at 110 Celsius. In Examples 29 and 30 the conversion is complete after 16 hours and in Examples 31 and 32 after 40 hours. In all cases, polyimide films are obtained that are tough and flexible.



   Examples 33-34
The polymerization is carried out in the same way as in Examples 28-31 with the exception, however, that 120 cm3 of dimethylacetamide are added together with the 8.0 cm3 of triethylamine in order to obtain a solution of the triethylamine salt of polyamic acid. With the aid of a doctor blade with an opening of 0.381 mm, foils are cast and dried in an air circulation oven at 120 ° C. for 15 minutes.



   The foils are soaked in baths which for example 23 consist of 220 cm3 pyridine and 280 cm3 acetic anhydride and for example 34 of 22 cm3 pyridine, 28 cm3 acetic anhydride and 450 cm3 carbon tetrachloride. In all cases, tough, flexible polyimide films are obtained. The conversion according to example 33 takes 24 hours and according to example 34 4 days. The films are extracted with dioxane and dried at 120.degree.



   Example 35
6.2 g of m-phenylenediamine and 10.56 g of benzidine and 25.1 g of pyromellitic acid dianhydride are weighed into a flask. The solid mixture is stirred in portions into 100 cm3 DMF while cooling to about 15 C using a water jacket. During the addition, the polyamic acid solution becomes very viscous, whereupon 400 cm3 of DMF are added. Foils are cast using a doctor blade with an opening of 0.508 mm and dried at 120-130 ° C. for 15 minutes. The films are then converted into the corresponding polyimide by soaking in a mixture of cyclohexane, pyridine and acetic anhydride (volume ratio 90: 6: 6) for 24 hours.

   The films are extracted by means of dioxane for 1 hour and dried at 130 ° C. for 2 hours. In this way, tough and flexible polyimide films are obtained.



   Example 36
6.2 g of m-phenylenediamine and 11.4 g of 4,4'-diaminodiphenylmethane and 25.0 g of pyromellitic acid dianhydride are weighed, mixed and stirred in portions into 100 cm3 of DMF while cooling with a water jacket to about 15 ° C. . The reaction mixture is gradually diluted in order to finally obtain a polyamic acid solution which contains 42.6 g of polymer (3% by weight), 190 cm3 of DMF and 126 cm3 of pyridine. With the aid of doctor blades and openings of 0.381 mm and 0.508 mm, films are cast and dried at 120 ° C. for 6-10 minutes. The inherent viscosity, measured in a 0.5 / O solution of DMF, is 2.03.

   These films are immersed in a mixture of tetramethylene sulfone and acetic anhydride (mixing ratio 4: 1) for at least 1 hour, after which the films are extracted with dioxane and dried at 120.degree.



   Example 37
10.0 g of 4,4'-diamino-diphenyl sulfide are dissolved in 75 cm3 of dimethylformamide. Then 10.15 g of pyromellitic acid dianhydride are added in portions and with cooling over the course of 15 minutes, a viscous solution of the corresponding polyamic acid being obtained. The last portion of the dianhydride is added together with 25 cm3 of dimethylformamide. With the aid of a doctor blade with an opening of 0.381 mm, foils are cast and dried in a stream of nitrogen at 120 ° C. for 10-15 minutes.



  The inherent viscosity of the polyamic acid solution thus obtained, measured in a 0.5% solution of DMF, is 1.2. The films are soaked in a mixture of cyclohexane, acetic anhydride and pyridine (mixing ratio 13: 1: 1). After 3 days, the solution is poured off, the films are rinsed with dioxane and immersed in dioxane for 1 hour. The films are then dried at 120 ° C. for 15 minutes and then heated to 300 ° C. for 15 minutes.

   The physical properties of the films at 23 C are as follows: Initial Modulus = 20389kg / cm2 Elongation = 7.8 / o Tensile Strength = 668 kg / cm2
The film is heat-treated for 1 minute at 380 ° C., whereupon it has the following properties: initial modulus = 18,280 kg / cm2, elongation = 10.8 "/ & tensile strength = 731 kg / cm2
Example 38
10.0 g of pyromellitic acid dianhydride and 11.39 g of 4, 4 'diamino-diphenylsulfone are weighed out, mixed and stirred in portions into 16 cm3 of DMF while cooling with a water jacket to about 15 ° C. for 90 minutes. The last portion of the reactants is added together with 20 cm3 of DMF.

   The reaction is allowed to proceed for 40 hours to give a polyamic acid solution containing 22% by weight of polymer. The inherent viscosity, measured in a 0.5% solution of DMF, is 0.64. Films are cast with the aid of a doctor blade with an opening of 0.254 mm and dried in an air circulation oven at 120 ° C. for 10 minutes. The films are then treated in a mixture of cyclohexane, pyridine and acetic anhydride (mixing ratio 13: 1: 1) for 3 hours, then immersed in dioxane and then dried at 120 ° C. for 15 minutes, giving satisfactory, self-supporting films.



   Example 39
A polyamic acid solution is obtained by mixing the following ingredients with exclusion of moisture for 18 hours at room temperature with stirring:
5.407 parts of m-phenylenediamine, 10.906 parts of pyromellitic acid dianhydride,
47, 15 parts of dimethylacetamide and
32.78 parts of pyridine.



  A portion of the viscous solution obtained is removed, diluted to 0.5 / o with dimethylacetamide and the inherent viscosity at 30.degree. A value of 1.94 is found. The solution is spun at room temperature through a spinneret which has 100 openings of 0.0762 mm into a bath containing acetic anhydride. The bath passage is 1.52 m. Single threads are removed from this bath via a roller at 9.75 m per minute, which are then fed to another roller at 16.46 m per minute in order to obtain a draw ratio of 1.7. The threads are then extracted in water for 1 hour and dried.

   The physical properties of the threads obtained are as follows: tenacity = 1.3 g / denier, elongation 45 / o, initial modulus (Young's modulus) 30 g / denier. If the winding onto the second roller takes place at a speed of 21.34 m per minute (stretch ratio 2.2), the threads have a tenacity of 2.2 g / denier, an elongation of 22 ouzo and an initial modulus ( Young modulus) of 43 g / denier.



   Example 40
A polyamic acid solution with the following ingredients is prepared as described in Example 39:
9, 913 parts 4, 4'-diamino-diphenylmethane, 10, 906 parts pyromellitic acid dianhydride,
47.08 parts of dimethylacetamide and
49.15 parts of pyridine.



   The logarithmic viscosity number is 1.4. Spinning takes place from a spinneret with 27 protruding openings, each 0.127 mm in diameter. The filaments are obtained in the same manner as in Example 38, using the roller speeds and draw ratios listed in Table IV below. The physical properties are also given in Table IV.



  Table IV
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   By heating the threads according to B for 5 minutes at 300 ° C., the properties are improved to 3.8/28/50. A further stretching of the threads according to C by a factor of 2.2 improves the properties to 3.3/26/65.



   Example 41
A similar polymer as in Example 40 is obtained by mixing the following ingredients for 6 hours at 0-25 ° C:
15, 84 parts 4, 4'-diamino-diphenylmethane,
17, 44 parts of pyromellitic acid dianhydride and
100 parts of dimethylacetamide.



  The viscous solution is diluted with 18 parts of dimethylacetamide and 20 parts of acetic anhydride. The solution is then spun through a spinneret with 100 openings, each 0.0762 mm in diameter, into a bath of 80% ethyl acetate, 10% pyridine and 10% acetic anhydride. The bath passage is 1.83 The threads are taken out at a speed of 6.40 m per minute and thereby stretched 2.05 times by passing them over a second roller at a speed of 13.11 m per minute.The threads are air-dried while Heated to 150 ° C. for 30 minutes, to 300 ° C. for 20 minutes and finally to 400 ° C. for 4 minutes.

   The thread properties are 1, 9/22/25 (TIEIMi) while the single thread denier is 3, 8.



   Example 42
A polymer solution is prepared according to the method of Example 41 with the following ingredients:
20, 00 parts 4, 4'-diamino-diphenyl ether,
21, 80 parts of pyromellitic acid dianhydride,
100 parts of dimethylacetamide and
68 parts of pyridine.



  The inherent viscosity is 1. 13. Filaments are produced by spinning this solution through a spinneret, which has 100 openings of 0.0762 millimeters each, into a bath of acetic anhydride using a bath passage of 1.83 m. The threads are guided around a first roller at a speed of 2.04 m per minute and then over a second roller at a speed of 7.16 m per minute with a stretch ratio of 3.5.

   After air drying, the threads have a denier of 3.6 and the following properties: 2, 2/11, 5/63 (T / E / M;). After heating the barrels to 600 ° C. for 2 minutes in a nitrogen atmosphere, they have the following properties: 4, 5/8, 4/65 (T / E / M;).



   Example 43
A polyamic acid is prepared according to the method of Example 41 from the following ingredients:
2, 16 parts 4, 4'-diamino-diphenyl sulfide,
2, 18 parts of pyromellitic acid dianhydride and
20 parts of pyridine.



  The inherent viscosity is 1.37. The solution is diluted with 6.7 parts of pyridine and spun in acetic anhydride as described in the above examples, whereby satisfactory threads are obtained.



   Example 44
A polymer similar to that in Example 43 is produced using the method according to Example 39 using the following components:
10, 816 parts 4, 4'-diamino-diphenyl sulfide,
10, 906 parts of pyromellitic acid dianhydride,
47, 15 parts of dimethylacetamide and
39.76 parts of pyridine.



  The inherent viscosity is 1.20. The polyamic acid solution obtained is spun in acetic anhydride as described in Example 39. The threads are removed at a speed of 2.29 m per minute and then wound up at a speed of 4.57 m per minute and a draw ratio of 2. The threads have the following properties: 1.67/35/29 (T / E / Mi). With a draw ratio of 2.5 during spinning and a further draw by 2.3 times, the threads have the following properties: 2, 2/39/29 (T / E / M;).



   Example 45
12.4 g (0.115 mol) of m-phenylenediamine are dissolved in 75 cm3 of dimethylformamide. Then 25.00 g (0.115 mol) of pyromellitic acid dianhydride are added, in portions with stirring or shaking, the solution being kept at about 15 ° C. by external cooling with running water. The last portion of dianhydride is added in 10 cm3 of dimethylformamide.



  A viscous material is obtained which is further diluted with 60 cm3 of dimethylformamide and then filtered through a pressure filter.



   Films are poured onto glass plates and dried in vacuo at 80 ° C. for 30 minutes. After removal from the plates, the films are treated in a mixture of cyclohexane, pyridine and acetic anhydride for 48 hours, then extracted in dioxane for 1 hour and then dried at 120 ° C. for 1 hour. The plate with the film is then heated to 300 ° C. for 15 minutes in a hot vacuum oven, the properties of the polyimide being improved.

   The removed polyimide film has the following properties: initial modulus = 22498 kg / cm2 elongation = 12 / o tensile strength = 6, 61 kg / cm2 retention of the degree of toughness = more than 3
Example 46
A polyamic acid solution is prepared in a manner practically similar to that in Example 45 using 6.2 g of p-phenylenediamine, 12.5 g of pyromellitic acid dianhydride and 120 cm 3 of dimethylacetamide. The solution is poured onto a glass plate.

   The film produced in this way is dried for 30 minutes at 80 ° C. and then the polyamic acid film is stripped from the glass plate and converted into a polyimide film by treatment in a mixture of pyridine and acetic anhydride (mixing ratio 3: 2). The film is then immersed in dioxane for 2 hours, dried at 130 ° C. for 1 hour and then heated to 380 ° C. for 1 minute.



   The properties of the film obtained are as follows: initial modulus = 36,560 kg / cm2 elongation = 5.5 / o tensile strength = 984 kg / cm2 retention of toughness level-more than 3 examples 47-50
Polyamic acid solutions are prepared as described in Example 45 using the components shown in Table V below.



   Table V
Reaction partner in g solvent in the example diamine dianhydride cm3 47 2, 01 PP 2, 37 PMDA 50 DMF 48 5, 17 DDP 10, 1 PMDA 75 DMF / P (3/2)
4, 22 PP 49 11, 2 PSO2P 10, 1 PMDA 150 DMF 50 9, 8 PSP 10, 0 PMDA 180 DMF
The solutions are cast into foils using a doctor blade having an opening of 0.318 mm (15 mil). After drying for 15 minutes in a circulating air oven under a dry nitrogen atmosphere, the polyamic acid films are stripped from the glass plates and converted into polyimide films.



   In Example 47, the film is treated in a mixture of benzene, pyridine and acetic anhydride (mixing ratio 2: 2: 1) for 20 minutes in order to convert the film into the polyimide. The film is then dried at 180 ° C. for 2 hours and then heated to 500 ° C. for 1 minute.



   In Examples 48-50, the films are treated in a mixture of cyclohexane, pyridine and acetic anhydride (mixing ratio 15: 1: 1) for 24 hours, then extracted in dioxane for 1 hour and finally dried at 130 ° C. for 1 hour. The properties of the films obtained are shown in Table VI below.



  Table VI
EMI14.1


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Example 51
5.8 g of hexamethylenediamine are dissolved in 83 cm3 of dimethylacetamide. The solution is cooled to about 15 ° C. using a water jacket and, while stirring, 10.9 g of pyromellitic acid dianhydride are added in portions.

   First a white, rubbery substance forms, which dissolves when stirred.



  The polyamic acid solution thus obtained contains 16.7% by weight of polymer. Foils are cast from this solution with the aid of a doctor blade with an opening of 0.254 mm and dried at 120-130 ° C. for 30 minutes.



   The films are soaked overnight in a mixture of 180 cm3 benzene, 120 cm3 pyridine and 50 cm3 acetic anhydride. The film is dried in vacuo for 2 hours at 160 ° C., a solid, tough, flexible film being obtained. Their infrared spectra indicate that it is a polyimide film.



   Example 52
7.9 g of 4,4'-dimethyl-heptamethylene-diamine are dissolved in 81 cm3 of dimethylacetamide. 10.9 g of pyro mellitic acid dianhydride are then added in portions, while stirring and cooling by means of a water jacket to about 15 ° C. The white, rubbery substance initially formed dissolves on stirring, giving a viscous solution. This solution contains 18.8% by weight of polyamic acid. This polymer solution is poured with the aid of a doctor blade which has an opening of 0.254 mm into a film, which is dried at 120 ° C. under the action of air for 30 minutes.



   The foil is soaked overnight in a mixture of 180 cm3 benzene, 120 cm3 pyridine and 50 cm3 acetic anhydride. It is then dried in vacuo for 2 hours at 160 ° C., a solid, tough, flexible polyimide film being obtained.



   The process described here is primarily concerned with the production of polyimides by a two-stage process, a polyamic acid being formed in the first stage and the latter being converted into a polyimide by treatment with acetic anhydride in the second stage. Of course, you can also use other organic dehydrating agents in the second stage. For example, primary, aliphatic acid anhydrides, such as. B. propionic anhydride, butyric anhydride and valeric anhydride.



   As can be seen from some examples, namely Examples 28, 37, 40-42 and 45-47, the properties of the polyimide products can be further improved by a third working step. This third step comprises heating the polyimide to a temperature of 300-600 ° C. for a short time interval, namely 15 seconds to 20 minutes.



   The polyimides obtained by the present process can be used for various fields of application with different physical shapes. Above all, they come into question as films and fibers. The valuable combination of desirable physical and chemical properties of this polymer are unique. Films and fibers made from this polymer not only have excellent physical properties at room temperature, but also retain their strength and their excellent behavior against loads even at elevated temperatures for longer periods. Thanks to this fact, they are economically suitable for many purposes. The polyimide polymers are resistant to corrosive, atmospheric influences as well as to decomposition by particles of high energy and gamma rays.

   The polymer does not melt even after prolonged treatment at 500 ° C., but retains the physical properties not previously achieved. Because of the unusual and surprising solubility of the polymer precursor, namely the polyamic acid, in the present manufacturing process, this polymer precursor can be converted into molded articles such as B. films and fibers, process according to the usual techniques and then transfer in situ into the polyimide polymer.



   The polyimide films can be used wherever films have previously been used. They can be used to a large extent for packaging, as wrapping material and for binding. In addition, this polymer can be used in a wide variety of forms as trim materials, cladding materials for automobile and aircraft construction, decorative edging materials, as electrical insulating material for high temperatures, in dry-type transformers, capacitors, as cable sheaths, etc., for packaging materials exposed to high temperatures or high-energy radiation, as corrosion-resistant pipes, as line materials, as linings for containers and for containers themselves as well as for layered structures,

   where the foils are glued to a sheet metal or metal foil, as well as for various other similar and related purposes. In fiber form, the new polymers offer possibilities for electrical insulation at high temperatures, as protective coverings and curtains, filter media, packaging materials, as brake linings, as clutch linings, etc.

 

Claims (1)

PATENT CLAIM Process for the production of polyimide molded articles, characterized in that if a polyamic acid is optionally present in salt form, its inherent viscosity in N, N-dimethylacetamide at 30 C and at a concentration of 0.5 g per 100 cm3 of solvent is at least 0.1 and which contains repeating pairs of amide groups which can be converted into imide groups and, if appropriate, carboxyl groups present in salt form, the number of imide groups possibly already present in the polyamic acid or its salt not exceeding the number of said pairs of groups convertible into imide groups , the said pairs of groups thermally and / or chemically after or under shaping into imide groups. SUBCLAIMS 1. The method according to claim, characterized in that the said pairs of groups are converted into imide groups in the presence of solvents. 2. The method according to claim or dependent claim 1, characterized in that the polyamide acid repeating units of the formula: EMI15.1 contains, where n. EMI15.2 Isomers denotes, R denotes a monocyclic oaer polycyclic or aromatic aliphatic tetravalent radical or an aliphatic tetravalent radical containing at least 2 carbon atoms, one carbon atom of the tetravalent radical being bonded to not more than 2 carbonyl groups, and R 'a divalent radical containing at least 2 carbon atoms means that is bonded to the nitrogen atoms through different carbon atoms. 3. The method according to claim or dependent claim 1, characterized in that the conversion of said pairs of groups into imide groups is only partially carried out by chemical treatment and then terminated by a thermal aftertreatment. 4. The method according to claim or dependent claim 1, characterized in that the polyamic acid is present in salt form, in particular in the form of the triethylammonium salt.