GB1559132A - Imidized polymers - Google Patents

Description

(54) IMIDIZED POLYMERS (71) We, ROHM AND HAAS (COM- PANY, a Corporation organized under the laws of the State of Delaware, United States of America, of Independence Mall West, Philadelphia, Pennsylvania 19105, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment:- This invention is concerned with imide polymers and their preparation.

The formation of imides by reacting ammonia, butylamine, dodecyl amine or octyl amine with polymethyl methacrylate is disclosed in Graves U.S. Patent 2,146,209, German Patent 1,077,872 and German Patent 1,242,369. Schroder et al U.S. Patent 3,284,425 and British Patent 926,629 disclose a route toward imidized acrylics by reacting polymethyl methacrylate with ammonium hydroxide, ammonium phosphate, alkyl amines or a combination of partial reaction with ammonium hydroxide followed by reaction with alkyl amine. British Patent 1,045,2129 discloses chemical modification of methacrylic acid/methacrylonitrile (MIMlA/ MAN) copolymers or terpolymers by heating at 180300 C., to give the cyclic amide product, optionally with a dispersing solvent.

German Patents 1,247,517; 2,041,736 and 2,047,096 show methacrylamide/methyl methacrylate (MAICM/MMA) copolymers, inert solvent, and heat to achieve imide formation accompanied by the evolution of ammonia.

Mose prior patents and literature on processes to imidized acrylics via reaction of ammonia and primary amines with polymethyl methacrylates, U.S. Patent 3,284,425 for example, are directed to an autoclave batch process requiring lengthy heating time, usually 7 hours or more, in the presence of inert dissolving or suspending solvent. U.S. Patent 3,557,070 describes a process for preparing ethylene/ methacrylic acid/methacrylamide terpolymers from an ethylene isopropyl methacrylate copolymer by heating the copolymer to the decomposition temperature (3250C.) of the isopropyl ester to form methacrylic anhydride units which are then reacted with gaseous ammonia to give methacrylamide and methacrylic acid residues in the polymer chain.

The reaction is run neat without solvent and the patent examples mention decomposition "zones". Although this patent does not men- tion that these reactions are taking place in an extruder, the Derwent abstract of this patent mentioned that these reactions may be run in an extruder. The use of extruders as polymer reactors has been shown as a route to copolyesters (Preparation and Properties of Copolyesters Polymerized in a Vented Extruder, J. Applied Polymer Science 12, 2403 (1968), nylon products (Direct Extrusion of Nylon Product from Lactams, Modern Plastics, August 1969-Warner Pfleiderer) and graft polymerization of polyolefins (Steinkamp et al U.S. 3,862,265). West German Patent 1,077,872 discloses an extruder process of imidizing acrylic polymers using a water solution of ammonia, but the product is a foamed strand with deficient thermal stability and which requires further processing before it can be used to fabricate useful items; furthermore, the proces described is not commercially feasible in that the foamed polymer exits the extruder under high pressure with free ammonia vapor.

We have now found that polymers, especially acrylic or methacrylic polymers, may be imidized in a process which uses low residence times and which lends itself to continuous operation and the control of the degree of imidization without substantial molecular weight degradation. Polymers may be provided which are substantially completely and/ or uniformly imidized and which have a desirable balance of properties, such as high, uniform molecular weight, improved thermal stability, thermaplostacity and no crosslinking.

Moreover, the process of the invention may lend itself to the control of the degree of imidization so that less than complete imidization may be achieved.

According to the invention, there is provided a process for the imidization of an imidizable polymer which comprises reacting said polymer with ammonia or a primary amine in an extruder under substantially anhydrous conditions, as hereinafter defined, at a temperature of from 200 to 4500 C. while applying subatmospheric pressure to at least one vent port of the extruder.

Generally, the polymer to be imidized is derived from at least one acrylic and/or methacrylic monomer, preferably at least one acrylic and/or methacrylic acid ester. The polymer may contain units derived from one or more other ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, acrylonitrile, styrene, ethylene and butadiene, but of course, the polymer must contain units containing groups capable of being imidized.

The polymer can comprise a single stage polymer and/or a multi-stage polymer whose outer stage contains groups capable of being imidized.

Generally the polymer contains at least 24 percent by weight, preferably at least 50 percent by weight, more preferably above 80 percent, and most preferably 95 to 100 percent by weight of said ester. Preferred are the species wherein the ester moiety contains 1 to 20 carbon atoms, most preferably methylmethacrylate (MMA) due to its lower cost and availability. Polymers of monomer systems comprised of at least 80 percent by weight MMA are very suitable.

The polymer can have a molecular weight falling within a wide range. Since commercially available acrylic polymers have intrinsic viscosities in dimethyl formamide, Cq1D,F, of from about 0.01 and up to about 7.0 and above, these are preferred. Acrylic polymers having an [qlDMP of 0.28 to 2.0 are most preferred.

Frequently the starting materials will comprise a single stage polymer dry or melt blended with a multiple stage impact modifier polymer, in which case the single stage polymer and primarily the outer stage of the, multiple stage polymer are imidized. Such blends are more compatible than blends of the imidized single stage polymer with the same multiple stage polymer, especially when the latter is not imidized. Preferred are blends of single stage acrylic polymers with 10 to 60% by weight multiple stage polymer.

The acrylic polymer can be in any form, but is generally in molding powder or granule form, and can be colorless or colored, but in some cases the imidization process affects the dyes or pigments, in which case the coloring agent is incorporated after pocessing.

The ammonia or primary amine is preferably a compound of the formula R3NH2 wherein R3 is hydrogen or substituted or un substituted alkyl or aryl having up to 20 carbon atoms.

The substantially anhydrous ammonia or primary amine, or mixtures thereof, is intro duced to the reaction zone in gaseous or liquid form under pressure, but in the case of primary amines can optionally be introduced in solid form. Due to ready availability, am monia and methylamine are most preferred of the compounds of the formula R,NH2, but others work very well in the process also, and also give very desirable products. Other suitable amines include, for example, ethyl, npropyl, n-butyl, heptyl, hexyl, octyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, isobutyl, sec-butyl, t-butyl, isopropyl, 2-ethyl hexyl, phenethyl, allyl, alanine, benzyl, parachloro benzyl, and dimethoxy phenethyl amines; alanine; glycine; 3'-aminoacetophenone; 2aminoanthraquinone; and p-aminobenzoic acid. Also cyclohexyl amine, 2 - amino - 4,6dimethyl pyridine, 3-amino Dhthalimide, 2aminopyrimidine, 2-aminopyn ine, 2-amino- thiazole, 5 - amino - 1 - H - aetrazole, aniline, bromoaniline dibromoaniline, tribromoaniline, chloroaniline, dichloroaniline, trichloroaniline, p-phenetidine, and p- toluidine are suitable.

It is important that little or no water be introduced with the ammonia or primary amine, never more than 2 percent by weight, preferably less than 1 percent, water based on ammonia or primary amine. For purposes of this invention, the term substantially anhydrous is defined by the aforementioned maximum water contents.

In accordance with the process aspect of the invention, the polymer is continuously fed to an extruder, and the ammonia or primary amine is introduced continuously at the same time, usually through an injection port. Unwanted by-products and excess ammonia or primary amine are removed by progressively reducing the pressure at downstream extruder vents, with at least one downstream vent at vacuum (sub-atmospheric pressure). Sometimes only one vent under vacuum is all that is necessary to adequately remove all byproducts and unreacted ammonia or primary amine. Preferably, a partial pressure of from 0.9 to 0.01 atmospheres is applied to the vent port.

The temperature in the extruder can be varied, depending on the nature of the starting materials, pressure, residence time, etc., but is especially dependent on the melt viscosity of the polymer being extruded. Usually, about 300 to 3750C. is suitable, but 200 to 4500 C. are the outer limits of the internal temperature of the extruder. Different sections of the extruder-reactor can be maintained at different temperatures.

Preferably the extruder is a multiple screw type, for example a twin screw tangential counter-rotating extruder or a twin screw intermeshing co-rotating extruder.

As high a pressure as possible is preferred, but again the pressure most suitable depends on other factors such as equipment limitations.

As low as atmospheric is operable, and as high as 1000 atmospheres is possible. In most embodiments, below 500 atmospheres pressure is suitable. When the primary amine is introduced in solid form, it can be introduced as a dry blend with the polymer rather than through a separate addition port.

The reaction time (or average residence time in the reaction zone) may be 0.1 to 1000 seconds, preferably 30 to 300 seconds.

The degree of imidization of the acrylic polymer is readily controllable in the process of the invention, and different degrees are chosen for different properties desired in the final product. The desired degree is consistently achievable by adjustment of the reaction parameters such as residence time and temperature. Although as low as 1% imidization can be achieved, at least 10% is usually needed for noticeable property improvement of the acrylic polymers. Up to about 100% imidization can readily be achieved by the process, meaning essentially all of the ester moieties of the acrylic polymer are converted to glutarimide moieties.

No catalyst is necessary in the process. This results in the great advantage of eliminating the necessity of catalyst removal. Small amounts of catalyst conceivably increase production rates, however.

No solvent is necessary, and it is preferred not to use any.

Preferably the process is one wherein anhydrous ammonia is introduced through an extruder addition port at a pressure of from 1 to 500 atmospheres, the average residence time is maintained at 30 to 300 seconds, a partial pressure of 0.9 to 0.01 is applied to at least one vent port, the temperature is maintained at from 325 to 3750C., and the reaction is conducted in the absence of solvent.

The product leaves the extruder in melt form, at which point other additives such as fibers, colors and flame retardants can be incorporated. Optionally, additives such as, for example, impact modifiers, pigments, fibers, stabilizers, lubricants, etc. can be added with the polymer prior to introduction in the reactor. The product can then be allowed to solidify in any desired form, e.g., sheet, tube, film, rod or strand, and the solidified product can be chopped into powder or granule form as desired.

The product of the process may have properties not possible with previous imide polymers, more specifically high tensile and flexural strength, solvent and hydrolysis resistance, thermal stability, high service temperature, good optical properties, weatherability, barrier properties, and others.

The imidized polymers are non-crosslinked, and this is evidenced by solubility in dimethyl formamide (DMF).

The uniformity of molecular weight and imide content of the imidized polymers is a particularly desirable property generally not achievable in prior processes. More specifically, most of the polymer molecules have the same imide content, and so the compositions have a narrow, controlled composition distribution.

The molecular weight of these compositions is the same as or very close to that of the starting acrylic polymer, which is also a great advantage as contrasted with prior processes in which molecular weight degradation occurred.

The invention also provides compositions comprising a thermoplastic polymer containing imide units of the structural formula

wherein R1, R2, and R2 represent hydrogen or Ct to C20 unsubstituted or substituted alkyl, aryl, alkaryl, or aralkyl, R1 and R2 being pre ferably derived from the acrylic or meth acrylic acid esters, and Ro being derived from the ammonia or primary amine or mixtures thereof, the polymer being further character ized as non-crosslinked, soluble in dimethyl formamide and having a degree of thermal stability as measured by thermogravimetric analysis in an air atmosphere such that the temperature at which said polymer has a 1% by weight decomposition is at least 285 0C.

The composition may comprise a single stage polymer containing said imide units and/or a multi-stage polymer whose outer stage contains said imide units. Preferably compositions comprising a blend of the two types of polymer contain a ratio of from 40 to 90% by weight of the single stage polymer and from 10 to 60% by weight of the multistage polymer.

The imidized polymer may contain other units derived from one or more ethylenically unsaturated monomers such as acrylic or methacrylic esters, acrylic or methacrylic acid, acrylnitrile, styrene, ethylene and butadiene.

Preferably, however, the polymer is derived from one or more acrylic and/or methacrylic esters, and when such polymers are 100% imidized the glutarimide structure is essentially the only repeating unit, but in the case of lower degrees of imidization, in addition to the glutarimide units, acrylic units of the formula

wherein R4 is lower alkyl or other radicals derived from the ester moiety of the acrylic unit will be present When acrylic units are present, the ratio of imide units to acrylic units is usually from 1:9 to 9:1, preferably 1:2 to 9:1, and more preferably 3:4 to 4:3.

The ammonia-derived imides are most preferred, and so R3 is preferably hydrogen. The acrylic polymer is preferably a homopolymer of methyl methacrylate.

Also preferred are polymers wherein 95-100% of the polymer units are imidized and those wherein 135% of the polymer units are imidized.

The thermoplastic polymer may be characterized as having an intrinsic viscosity in dimethyl formamide of from 0.1 to 7.0. The polymer may also be soluble in tetrahydrofuran and in dimethyl sulfoxide.

Impact modifiers of the ABS (acrylonitrile/ butadiene/styrene), MBS (methyl methacrylate/butadiene/styrene) and all acrylic type have been found to be useful for improving the impact strength of the imide polymers while retaining high service temperature. The ratio of impact modifier to imide polymer can be varied over a wide range, depending upon how much impact modification is needed for the particular application. Ratios of impact modifier to imide polymer of from 1:99 to 70:30 are useful, with the preferred range being 5:95 to 60:40. Impact modifiers can be single or multiple stage polymers. In the case of multiple stage polymers, the impact modifier can have a hard or soft first or "core" stage followed by stages varying in hardness or softness. Exemplary impact modifiers are those disclosed in U.S. Patent Specification 3,985,704 and U.S. Patent Specification 3,808,180 of April 30, 1974.

The imide polymers of this invention do not have any significant odor when prepared under the preferred conditions, and can be processed by injection molding, extruding, milling, or any other polymer processing procedure with- out odor of degradation. Even at temperatures of over 400"C., no polymeric decompositions so as to give off ammonia or amine takes place.

The thermal stability of the polymers of the invention is one of the distinguishing advantages of the materials as compared to analogous prior polymers. With thermogravimetric analysis, TGA, as the test method, the polymers of the invention have a degree of thermal stability wherein the temperature at which the polymers have a 1% weight loss is at least 285"C. in air which is shown in the Examples following to correspond to at least 3000;C. in nitrogen for the particular polymer tested therein.

Dynamic thermogravimetric analysis (TGA), as used in this specification, is a standard test conducted with a programmed temperature increase rate of 200C./min. in either an air or a nitrogen atmosphere on a duPont thermogravimetric analyzer in combination with a differential thermal analyzer as described in duPont Instrument Products Division Preliminary Product Bulletin 9501 (A36177).

Various adjuvants may be added to the imidized polymer. For example, from 0.1 to 25 percent by weight flame retardant can be employed, preferably compounds of bromine, chlorine, antimony, phosphorus aluminum trihydrate, certain organic compounds containing two or more hydroxyl groups, or mixtures thereof. More specific examples of flame retardants are triphenyl phosphate, phosphonium bromide, phosphonium oxide, tris (di-bromo propyl) phosphate, cycloaliphatic chlorides, chlorinated polyethylene, antimony oxide, ammonium polyphosphate, decabromo-diphenyl ether and chlorinated polyphosphonate. The high service temperature of the poly (glutarimide) in its base resin permits larger amounts of fire retardants to be added than can be added to other base resins, while yet maintaining acceptable service temperature.

A wide variety of fillers can be employed, at filler levels of from 5 to 80 percent. Surprisingly large amounts of filler such as hydrated alumina can be blended with the glutaramide polymer base resin, up to 60 to 70 percent, while maintaining thermoformability. On the other hand, most thermoplastic systems cannot adept more than about 40 percent inert fillerwith retention of thermoformability. The ftimide polymers can be blended with glass reinforcement at glass levels of 1 to 60 percent to enhance strength, stiffness, creep res > stance and deformation resistance at high temperatures and to reduce the thermal expansion co-efficient The compatibility of the glasreinforcement with the imide polymers is unusually high and frequently permits the use of glass reinforcement which has standard coupling agents rather than specially prepared, reinforcements.

If desired, the imide polymers can be foamed. A variety of methods of foaming can be used, for example chemical blowing agents can be mixed with the imide polymer and fed to an injection molding machine which plasticizes the polymer7oand decomposes the blowing agent under pressure in the cylinder of the injection molding machine with subsequent rapid feeding to the cavity of the mold. Articles of variable density, for example, 0.4 to 1.2 g/cc, can be obtained. Such foamed parts have advantages of rigidity, design freedom, acoustic dampening, and corrosion resist ance. In other embodiments, glass fibers can be added along with a chemical blowing agent so as to produce a foamed, strong, heat resistant part with an aesthetically appealing surface and excellent chemical and stain resistance. Also, fillers such as, for example, alumina trihydrate can be included with chemical blowing agent and, for example, extruded into flat sheet having a variety of desirable properties such as lower density, good flexural modulus and flame resistance.

The imidized polymers of this invention have utility as molding powders, pellets or granules for use in making molded articles such as tail light lenses, toys, watch crystals, to name but a few examples. Also, the polymer can be in the form of sheet, rod or tube.

The compositions of the invention can also be used as oil additives due to good viscosity characteristics, not adding to viscosity at low temperatures but thickening oil at higher temperatures.

Thus, one embodiment of the invention provides a synthetic or natural oil having dissolved or dispersed therein imidized poly mer as previously described.

Some preferred embodiments of the invention will now be more particularly described in and by the following Examples in which all parts and percentages are by weight and all temperatures are in C, unless otherwise specified.

In the Examples the following abbreviations are used: P - polymer of MMA - methyl methacrylate EMA - ethyl methacrylate RA - ethyl acrylate BA - butyl acrylate MA - methyl acrylate AA - acrylic acid MAN - methacrylonitnle E - etylene VA - vinyl acetate DMF - dimethyl formamide MDC - inethylene dichloride EXAMPLES 1 to 45.

In a twin screw counter-rotating extruder set up with a feed port for introducing acrylic polymer in solid form such as granule, pellet, or powder, an addition port for introducing ammonia or primary amine at elevated pres sure, an extruder barrel heated or cooled with oil in five separate zones, each about 84 cm., a die which serves as the exit port for the polymer product, and a vent port operated under vacuum and located in the last zone, acrylic polymer as specified in Table I is introduced via the feed port.

Amine or ammonia reagent, as specified in Table I, is introduced in the extruder barrel just after a non-flighted screw section (compounder) which forms a vapor seal which keeps the reagent from going back toward the polymer feed port. The reagent contacts and mixes with the polymer as it moves forward through the reaction zone, under pressure as specified in Table I. The unreacted reagent as well as the volatile products and byproducts of the reactor are removed under vacuum at the vent. The imidized polymer product leaves the extruder through the die in melt form, non-foamed, and essentially free of volatile materials.

The extruder used for Examples 7 to 21 and 27 to 45 includes two additional vents, the first being a vent upon which a high pressure is maintained by means of a rectrictive valve on the vent, the second being at atmospheric pressure, said vents being located after the amine introduction port but before the vacuum vent which is at the negative pressure specified in Table I.

The extruder used for Examples 22 to 26 is the same as for Examples 7 to 21 and 43 except that it includes third and fourth additional vents, located before the amine introduction ports, the third being at atmospheric pressure and the fourth being at vacuum.

In Table I, the degree of imidization is indicated by % nitrogen (%N), and the following base polymers are used: A. pMMA of [#]DMF of 1.15.

B. p(MMA/EA), in a weight ratio of 96/4 in the polymer, and of [#]DMF=0.80.

C. p(MMA/EA), 96/4, and of [#]DMF= 0.35.

D. pMMA of [Q]DMF=1.35 E. pMMA [#]DMF=0.80.

F. p(MMA/EA), (95/15), [#]DMF=1.65.

G. A syrup of 50% A and 50% MMA monomer.

H. A syrup of 60% B with 40% of a monomer mixtures of MMA and EA in a ratio of 85/15.

I. pMMA of [#]DMF=2.7.

J. p(EMA/BA/MA), 75/25/25 and [#]DMF=0.51.

K. p(MMA/BA), 50/50, [#]DMF=0.80.

L. p(MMA/AA), 95/5, [#]DMF=1.05.

M. p(MMA/MAN), 90/10. [#]DMF=0.70.

N. p(MMA/MAN), 98/2 and [#]DMF=1.35.

O. p(MMA/VA), 80/20, [#]DMF=0.51.

P p(MMA/E), 75/25, [#MDO=0.45.

Q. p(MMA/E),75/25, [#]MDO=0.57.

R. (pMMA), [#]DMF=1.05.

S. p(MMA/EA), 50/50, of [#]DMF=0.64.

T. pMA, [#]DMF=3.0.

U. p(MMA/E), 80/20, [#]MDO=1.0.

V. pMMA, [#]DMF=0.64.

W. p(MMA/BA), 95/5, [#]DMF=0.76.

X. 50/50 Blend of I and V.

In certain examples, the product produced in a different Example is introduced as feed; this is indicated by entry in the Table of that Example number under "feed".

TABLE I Average Pressure Polymer Amine Amine Barrel in Vacuum Product Data Example Rate Amine Rate Pressure Extruder Temp. Vent VICAT No. Feed g/min. Type g/min. atm RPM C atm %N C.

1 G 27 Ammonia 7 29.9 150 310 0.16 1.47 134 2 1 31 " 7 35.4 150 310 0.16 3.19 152 3 2 26 " 7 50.4 150 310 0.16 5.59 190 4 A 23 " 8 49.7 150 310 0.23 3.26 157 5 4 32 " 8 61.2 150 310 0.26 6.57 188 6 B 31 " 6 23.8 150 310 0.16 0.74 130 psig 7 C 67 Methyl 8 360 300 260 0.10 1.22 8 7 70 " 8 370 300 260 0.16 2.86 9 8 62 " 8 370 300 260 0.16 5.06 10 B 50 " 10 175 360 280 0.16 3.55 126 11 B 49 " 13 450 315 280 0.16 5.32 142 12 B 47 " 30 450 315 280 0.16 6.81 154 13 B 46 " 34 650 310 280 0.16 7.20 161 14 B 18 " 12 700 315 280 0.16 8.00 182 15 B 25 " 17 670 312 280 0.16 8.20 183 TABLE I (Continued) Average Pressure Polymer Amine Amine Barrel Vacuum Example Rate Amine Rate Pressure Extruder Temp. Vent Product Data No. Feed g/min. Type g/min. psig RPM C. atm. %N VICAT 16 B 25 Ammonia 7 740 315 300 0.13 5.01 164 17 D 28 " 7 850 315 310 0.20 7.54 199 18 D 23 " 11 775 365 310 0.23 7.63 200 19 D 58 " 5 775 450 310 0.13 4.44 160 20 D 59 " 3 725 450 310 0.13 2.18 141 21 D 46 " 6 825 455 310 0.10 5.58 171 atm 22 E 50 Ammonia 10 53.8 350 310 0.10 3.2 155 23 E 50 Methyl 8 34.0 250 310 0.10 7.1 160 24 E 50 Cyclohexyl 15 20.4 275 310 0.10 6.8 165 25 F 48 Ammonia 12 55.1 200 310 0.10 3.3 160 26 F 48 Methyl 10 34.7 200 310 0.10 7.0 158 TABLE I (Continued) Polymer Amine Average Example Rate Rate Extruder Barrel No. Feed g/min. Amine g/min. RPM Temp. C 27 I 50 Ammonia 5 250 300 28 J 25 Methyl 2 150 250 29 K 100 Ammonia 10 400 310 30 L 35 Methyl 5 200 275 31 M 60 Ammonia 10 200 290 32 N 40 Methyl 3 175 310 33 O 80 Ammonia 7 350 250 34 P 30 Methyl 2 250 310 35 Q 50 Ammonia 5 275 275 36 R 100 Dodecyl 30 300 250 37 S 60 Aniline 10 310 310 38 T 30 N-vinyl 7 200 260 39 U 40 Cyclohexyl 15 275 275 40 V 100 Isopropyl 30 400 290 41 W 50 n-butyl 15 300 265 42 S 35 Ethyl 7 250 310 43 S 25 Trichloroaniline 15 150 310 44 X 50 Ammonia 12 275 310 45 R 50 A blend of 5% 25 300 300 ammonia, 95% butylamine EXAMPLE 46.

In an extruder reactor as used in Examples 1 to 45 except with a configuration:polymer feed/high pressure vent/amine feed/atmospheric vent/vacuum vent/exit die, base polymer A is imidized under the same conditions as IExample 7 resulting in a nitrogen content of 1.5% and bonds in its IR spectra indicating the formation of imide groups.

EXAMPLE 47.

To the feed throat of a twin screw counterrotating tangential extruder with a screw diameter of 511.4 cm a copolymer of 96% methyl methacrylate with 4% ethyl acrylate with [n]DYF of 0.84 is introduced at 1430 kg/ lir. This polymer is compacted, melted, and formed into a continuous stream of molten plastic which is propelled along in the extruder barrel. Through the use of non-flighted and reverse-flighted screw sections the extruder

No imidization was observed in any of these attempts to repeat Example 7 of the reference.

EXAMPLE 49 (Comparative).

A. In accordance with the invention, an 0.8" Welding Engineers twin screw extruder having the configuration described in Examples 1-6 is used to completely imidize a pMMA having a [11,,F of 1.65 with non aqueous ammonia under a pressure of 53 atm. and temperature of 262700 C. at a point about 1/3 the way down the screw. A vacuum of 0.9 to 0.001 is applied to the vacuum vent.

A smooth continuous product strand exits the extruder. The product does not require drying, and it can be further processed with out intermediate steps. No ammonia vents into the environment, and all by-products are replaceable.

The product is poly(glutarimide), and is tested for thermal stability by the dynamic thermogravimetric analysis method (TGA) with results reported in Table II.

B. To show the critical importance of the amine being non-aqueous and the subatmospheric pressure being applied to at least one vent port, a comparative experiment was conducted using the same conditions of A, supra, but using aqueous ammonia (NH,/H,O ratio 80/20 by wt.) and plugging the vacuum vent.

The product exited the extruder in foamed, discontinuous masses propelled by the ammonia pressure at high velocity and was stopped by a shield mounted about 4 feet from the extruder die. Large quantities of ammonia vented from the die into the environment. The product was ground to a fine powder and had to be dried. It was vacuum dried at 1200C. for 16 hours and tested for thermal stability by dynamic TGA. with the results reported in Table II.

Although the products produced in accordance with the invention (A, supra) and in this comparative experiment, B, both had equal degrees of imidization (100%) and melt viscosity, the comparative experiment produced a product which was significantly less thermally stable than the analogous product of the invention. The results in Table it imply that at typical processing temperatures, around 300"it., product A only loses around 1% of its weight, whereas product B loses over 2%.

This difference can mean the difference between a no bubble, smooth surfaced product and a bubble-containing, rough-surfaced product.

TABLE II THERMAL STABILITY Dynamic TGA, Temp. Increase Rate 200C./min. Temp., or.,: Air or Nitrogen, at which total wt. loss is as indicated % Weight Loss AIR NITROGEN A B A B 1 285 100 300 105 2 370 175 400 275 3 385 350 440 385 4 395 380 420 405 5 400 390 420 410 NOTE: A - represents invention B - is comparative EXAMPLE 50.

This Example compares the polymers prepared in Graves U.S. Patent 2,146,209, Schrbder et al U.S. Patent 3,284,425 with the polymers of the invention.

A. GRAVES The polymer prepared in Examples I and II of the Graves Patent are supposedly polymethacrylimides. However, according to these Examples the polymers actually produced were soluble in dilute ammonia and boiling methanol. The polyglutarimide polymers of the present invention are insoluble in dilute ammonia and insoluble in boiling methanol.

The Graves produce appears to be a copolymer of methacrylimide, methacrylamide, and ammonium methacrylate.

B. SCHRöDER ET AL AUTOCLAVE For purposes of comparison, Example 1 of U.S. 3,284,425 is repeated using 120 parts polymethyl methacrylate heated for 7 hours at 230 C. in a Parr stirred autoclave with 129 parts of a 331/3% aqueous solution of methylamine and 780 parts. A pressure of 31 atm. develops. The reaction product comprises a watery phase and 32.7 parts of a solid polymer which was washed and analyzed to have a nitrogen content of 8.50.2%. The 32.7 parts represents 34.6% of the initial charge.

The Schröder polymer is compared to the polymethyl-methacrylate/methyl amine reaction product prepared in the extruder in accordance with the invention with the results reported in Table III.

These data show that the Schröder et al polymer is clearly less thermally stable than the polymer prepared in accordance with the invention; the SchröAer et al polymer exhibits weak, ill-defined glass transition temperature as compared to the polymer of the invention; and it begins to soften at a lower temperature (DTUFL and Vicat). The translucency of the schröder et al material seems to indicate a non-uniform imide level, as compared to the transparent, and hence uniform, polymer of the invention. The difference in water resistance indicates inferior properties of the Schröder et al polymer.

EXAMPLE 51.

Six and one-half parts of the poly(glutarimide) polymer produced in accordance with Example 18 are blended with three and onehalf parts of the MBS impact modifier produced in accordance with Example 1 of U.S.

Patent Specification 3,985,704 and 0.5 weight percent antioxidant at 460-5'100F. in a vacuum-vented single screw extruder to produce translucent strands which are then pellet ized, dried at 90"C. and injection molded at extruction temperaturs. The polymer blend produced had a Vicat of 185 C., a DTUFL ( C.) of 180 (66 psi), 160 (264 psi), and 170 (264 psi annealed). The product had a notched Izod impact strength of 1.1 ft.-lbs./ in. and tensile modulus of 4x105, tensile strength of 9x10 psi at break.

EXAMPLE 52.

Compositions similar to that of Example 51 except using the impact modifier produced in accordance with Example 1 of U.S. Patent 3,808,180 with imide to modifier ratios of 3/2 and 1/1 gave similar results. Substitution of MBS and ABS modifiers gave excellent balance of properties.

EXAMPLE 53.

A composition as per Example 51, except with the ratio of poly(glutarimide) to MBS modifier of 6 parts to 4 parts, gave translucent articles having the following properties, Vicat 135 C.; DTUFL 120 C. (66 psi), 100 C.

(264 psi); notched Izod 2.5 ft.-lbs./in.; tensile modulus 3x105 psi; tensile break strength 6X > 103 psi.

EXAMPLE 54.

Example 51 was repeated except substituting one part of polycarbonate for one part polyglutarimide, producing opaque polymer blends having the following properties, Vicat 170 C; DTUFL 170 C. (66 psi), 135 C.

(264 psi), 145 C (264 psi, annealed); notched Izod 2.1 lns./in.; tensile modulus 3x105 psi; tensile break strength 7x10 psi.

EXAMPLE 55.

Example 51 was repeated except using 5.9 parts polyglutarimide to 4.1 parts impact modifier, and substituting for the MBS impact modifier one of the following formula: Bd/St//MMA//St//MMA/AN/St: 71/3//3//11//4/4/4.

The properties of the resultant blend were as follows: Vicat 1600C.; DTUFL 1470iC.

(66 psi), 1400C. (264 psi); notched Izod 1.5 ft.-lbs./in.; tensile modulus 3x105; tensile strength at break 8x10 psi.

TABLE III AUTOCLAVE EXTRUDER TEST (Schröder) (Invention) % Nitrogen, # 0.2 8.5 8.3 Intrinsic Viscosity Melt Rate Flow Condition C 0.45 1.0 In DMF insoluble 0.35 In 95/5 DMF/Formic Acid 0.24 0.20 In tetrahydrofuran insoluble soluble Vicat Temperature C. 170 177 DTUFL by TMA C. 90 122 Tensile Impact (avg. of 5 measurements with large amount of scatter and therefore low confidence value) 20.7 13.4 Tensile Break strength, psi 12,800 12,100 Modulus, psi 519,000 518,000 After 35 hrs, in boiling water % weight increase 5.2 3.3 Surface condition badly attacked good optical properties opaques/white clear/light yellow Original Optical Properties translucent/grey clear/yellow Differential Thermal Analysis (DTA) Nature of Transition weak ill defined sharp well defined Transition Temperature, C 194 179 Thermogravimetric Analysis (TGA) 1% Wt. Loss (Air) C. 240 365 1% Wt. Loss (N2) C. 245 395 3% Wt. Loss (Air) C. 360 395 3% Wt. Loss (N2) C. 395 410 Nuclear Magnetic Resonance Analysis, presence of signal at 3.14 a indicating presence of at least 1% by weight amide groups present absent

Claims (1)

1. WHAT WE CLAIM IS:

   1. A process for the imidization of an imidazible polymer which comprises reacting said polymer with ammonia or a primary amine in an extruder under substantially an hydrous conditions, as hereinbefore defined, at a temperature of from 200 to 450"C. while applying subatmospheric pressure to at least one vent port of the extruder.

   2. A process as claimed in Claim 1 wherein the polymer is derived from at least one acrylic and/or methacrylic acid ester.

   3. A process as claimed in Claim 1 or 2 wherein the ammonia or primary amine is introduced through an extruder addition port at a pressure of from 1 to 1000 atmospheres.

   4. A process as claimed in any of Claims 1 to 3 wherein the average residence time is 0.1 to 1000 seconds.

   5. A process as claimed in any of Claims 1 to 4 wherein the degree of imidization is determined by control of the average residence time and temperature.

   6. A process as claimed in any of Claims 1 to 5 wherein the temperature is from 300 to 3750it.

   7. A process as claimed in any of Claims 1 to 6 further characterized as being carried out in the absence of solvent.

   8. A process as claimed in any of Claims 1 to 7 further characterized as carried out in the absence of a catalyst.

   9. 9. A process as claimed in Claim 1 wherein anhydrous ammonia is introduced through an extruder addition port at a pressure of from 1 to 500 atmospheres, the average residence time is maintained at 30 to 300 seconds, a partial pressure of 0.9 to 0.01 is applied to at least one vent port, the temperature is maintained at from 325 to-375 C., and the reaction is conducted in the absence of solvent.

   10. A process as claimed in any of Claims 1 to 8 wherein a partial pressure of from 0.9 to 0.01 atmospheres is applied to tbe vent port.

   11. Polymer whenever produced by a pro cess as claimed in Claim 1.

   12. Polymer whenever produced by a pro cess as claimed in any of Claims 2 to 10.

   13. A composition comprising a thermo plastic polymer containing imide units of the structural formula

   wherein R1, R2 and R2 represent hydrogen or C1 to C24 unsubstituted or substituted alkyl, aryl, said polymer bemg turther characterlzee as non-crosslinked and soluble in dimethyl formamide, and having a degree of thermal stability as measured by thermogravimetric analysis in an air atmosphere such that the temperature at which said polymer has 1% by weight decomposition is at least 285"C.

   14. A composition as claimed in Claim 13 which comprises a single stage polymer containing said imide units and/or a multi-stage polymer outer stage contains said imide units.

   15. A composition as claimed in Claim 14 which comprises from 40 to 90% by weight of single stage polymer and from 10 to 60% by weight multi-stage polymer.

   16. A composition as claimed in any of Claims 13 to 15 wherein the polymer contains other units.

   17. A composition as claimed in Claim 16 wherein the other units are derived from one or more of acrylic esters, methacrylic esters, acrylic acid, methacrylic acid, acrylonitrile, styrene, ethylene and butadiene.

   18. A composition as claimed in any of Claims 13 to 17 wherein 95 to 100% of the polymer units are imide.

   19. A composition as claimed in any of Claims 13 to 17 wherein 1 to 35% of the polymer units are imide.

   20. A composition as claimed in any of Claims 13 to 19 wherein the polymer contains said imide units and units derived from at least one acrylic and/or methacrylic acid ester, the numerical ratio of the imide units to acrylic and/or methacrylic units being from 1:2 to 9:1.

   21. A composition as claimed in any of Claims 13 to 20 wherein the thermoplastic polymer has an intrinsic viscosity in dimethyl formamide of from 0.1 to 7.0.

   22. A composition as claimed in any of Claims 13 to 21 further characterized as being soluble in tetrahydrofuran and dimethyl sulfoxide.

   23. A composition as claimed in any of Claims 13 to 22 which further includes an impact modifier.

   24. A composition as claimed in Claim 23 wherein the impact modifier is a multi-stage polymer.

   25. A composition as claimed in Claim 23 or 24 wherein the impact modifier comprises at least one of the type acrylonitrile/butadiene/styrene, methyl methacrylate/butadiene/styrene and all acrylic.

   26. A composition as claimed in any of Claims 13 to 25 in the form of sheet, rod, tube, powder, granule or molded article.

   27. A composition as claimed in Claim 13 prepared by a process according to any of Claims 1 to 10.

   218. A composition as claimed in any of Claims 14 to 26 prepared by a process according to any of Claims 1 to 10.