POLYAMIDE-POLYOL BLOCK COPOLYMERS AND ANIONIC POLYMERIZATION PROCESS

Abstract: Impact modified polyamide/polyether block copolymers have increased impact strength for corresponding polyol concentration, which can be achieved using certain difunc­ tional and tri-functional symmetrical triazine derivatives as the co-catalyst/coupling agent, and lactamyl salts as the catalyst. Also disclosed is an improved anionic polymeriza­ tion process, especially suitable for reaction injection mold­ ing. The impact modified polyamide/polyether block copolymers have segments of formulae I and II and either III or IV or both III and IV:

Description: The present invention relates to block copolymers having polyamide blocks formed from lactam monomers and polyol blocks, and to anionic polymerization processes for producing such block copolymers. The anionic polymerization of lactams, such as caprolactam, is known to proceed through the use of two solutions, as for example in US-A-3017391. The first solution, known as solution A, contains molten caprolactam in which is dissolved an akali metal or akaline earth metal-containing material which, in situ, causes the formation of a caprolactamyl anion. The active catalyst may thus be lithium or sodium caprolactam or may be bromomagnesium caprolactam or similar ionic compounds. The second solution, known as solution B, contains molten caprolactam in which is dissolved a co-catalyst, which in the above patent may be an acyl biscaprolactam such as terephthaloyl bis(caprolactam). Mixing solutions A and B under appropriate temperature conditions causes polymerization to form a polyamide having, at some intermediate point in the chain, a terephthaloyl moiety between amine ends of polyamide chains, having caprolactamoyl or carboxy end groups and, in most instances, some degree of branching such as at the nitrogen of an amide ligand. US-A-3448085 describes a similar anionic polymerization process using, as the co-catalyst in solution B, symmetrical triazine derivatives such as 2,4,6-trichloro-sym-triazine (also known as cyanuric chloride), 2,4,6-trimethoxy-sym-triazine and 2,4,6-triphenoxy-sym-triazine. See US-A-3485822. More recently it has been proposed to prepare molded parts by reaction injection molding, injecting into a mold a reactive mixture containing caprolactam or similar lactam monomers. While such a process may proceed through anionic polymerization using similar catalysts and co-catalysts to those described above, it is generally desired to achieve faster cycle times at higher temperatures and to obtain parts with modified properties, and especially increased impact strength, compared to those prepared by the processes described above. US-A-4031164 discloses block copolymers having lactam-derived blocks (polyamide blocks), polyol blocks and diacyl moieties. It is indicated that, while proportions of polyamide and polyol blocks may vary (see column 11), increased amounts of polyol lead to products with decreased rigidity and increased elongation and water absorption; and it is further reported that low impact strengths are achieved when less than 18% polyol is present. FR-A-2202115 discloses that the shock resistance of polyamides can be increased, without greatly altering other properties such as bending resistance and elastic modulus, by anionic polymerization of lactams with polyalkylene glycols of elevated molecular weight, especially from 18,000 to 100,000. Conventional activators for anionic polymerization, including N-acyl lactams, substituted triazines, carbodiimides, cyanamides, isocyanates and masked isocyanates can be used, e.g. in amounts from 0.1 to 1 mol %. It has been discovered that block copolymers of increased impact strength for corresponding polyol concentration can be achieved using certain di-functional and tri-functional symmetrical triazine derivatives as the co-catalyst/coupling agent. Such results lead to an improved anionic polymerization process, especially suitable for reaction injection molding, and to improved block copolymer products. Accordingly, the present invention includes an impact modified polyamide/polyether block copolymer having segments of formulae I, polypropylene oxide segments II, the molecular weight of each segment II being from 500 to 5000 and either III or IV or both III and IV: with n being an integer of 3-12; m being a number different for individual segments, of 1-150; and R' being a monofunctional moiety, inert during polymerization, selected from alkyl, aryl, dialkylamino and diarylamino; with the triazine rings of segments III and IV being bonded only to the amino of segment I or to either oxygen of segment II; the terminal carbonyl of segment I being bonded only to either oxygen of segment II or to a terminal -OH or the terminal -NH- of segment I being bonded only to the triazine ring of segment III or IV; the total segment I constituting between 55 and 98 weight percent of the polymer and the total segment II constituting between 1 and 40 weight percent of the polymer. The present invention also includes a method for the formation of the above-defined impact-modified polyamide block copolymers which comprises reacting: (a) a cyclic lactam of the formula: with n being as defined above; (b) polypropylene oxide having a molecular weight from 500 to 5000 (c) a catalyst selected from alkali metals, alkali metal hydrides, alkyl alkaline earth monohalides and aryl alkaline earth monohalides or a lactam salt of the formula where M⁺ is an alkali metal cation or alkaline earth metal monohalide cation; and (d) a triazine co-catalyst/coupling agent selected from and mixtures thereof; wherein R'' is a reactive substituent selected, independently at each occurrence, from the group consisting of alkoxy, aryloxy, halo, oximino, imidazolyl and N-lactamyl; and R' has the meaning given above, the polyether being reacted in an amount between 1 and 40 percent of the total reactants. According to one embodiment of the invention, the polymerization reaction can be brought about by mixing two solutions, the catalyst being contained in the first solution, and the triazine co-catalyst/coupling agent being contained in the second solution. Preferably, the first solution contains of first portion of cyclic lactam and the catalyst, while the second solution contains a second portion of the cyclic lactam, the triazine co-catalyst/coupling agent and the polypropylene oxide. In a preferred embodiment, the two solutions are mixed and injected into a mold maintained at a temperature sufficient to cause polymerization into a shaped article of the impact-modified block copolymer. There are four necessary reactants in the present process, which find counterparts as three types of residues in the present product. The lactams (e.g., caprolactam) find counterparts as polyamide blocks in the product block copolymers. The poly(propylene oxide) corresponds to polyether blocks. The triazine co-catalyst/coupling agents represented by formulae IIIa and IVa, above, form di-functional and tri-functional residues III and IV in the block copolymer. The lactam monomer used to form polyamide blocks is preferably caprolactam (n=5), but can also be larger lactams (n=6 to 12) such as lauryllactam (n=11), or smaller (n=3 or 4) as in pyrollidone (n=3). Mixtures of lactams, such as a major proportion of caprolactam and a minor proportion of lauryllactam, may be used. Polypropylene oxide includes copolymers, A-B-A, wherein B is a relatively long string of propylene oxide-derived moieties, and A is a relatively short string of ethylene oxide-derived moieties. In limited experimentation, however, the pure poly(propylene oxide) polyether, with a predominance of secondary alcohol end-groups, appeared superior for the present process and product to such A-B-A block copolymers of propylene oxide and ethylene oxide, with primary alcohol end-groups. If, however, R'' of the co-catalyst is not chloro (as it was in these limited experiments), then the superiority of secondary alcohols may not persist. The chain length of the polypropylene oxide will vary, generally on a random or statistical basis from molecule to molecule, and average molecular weights range from 500 to 5000, more preferably from 1000 to 3000. The catalyst can be any of those used conventionally for anionic polymerization, being or forming in situ lactamoyl anions. Suitable catalysts include alkali metals (lithium, sodium or potassium), alkali metal hydrides (lithium, sodium or potassium hydride), alkyl alkaline earth metal monohalides (QMgX, QCaX), wherein Q is alkyl of 1-6 carbons, for example, and X is Br, Cl or I), aryl alkaline earth metal monohalides (Q'MgX, Q'CaX, wherein Q' is phenyl, substituted phenyl, naphthyl); or a lactamyl salt wherein n is an integer of 3-12 and M+ is an alkali metal cation (lithium, sodium or potassium cation) or an alkaline metal earth monohalide cation (MgBr⁺, MgCl⁺, MgI⁺, CaBr⁺, CaCl⁺, CaI⁺). Preferred catalysts are those having Mg, Li, Ca or Na as the metal, with Mg, Na and Li being more preferred. Bromomagnesium caprolactam, sodium caprolactam and magnesium and sodium compounds producing these in situ are most preferred. The preferred group of co-catalyst/coupling agents are those of formula IIIa having two reactive substituents R'' and one non-reactive substituent R'. The reactive substituent R'' may be alkoxy (as from 1-6 carbons), aryloxy (such as phenoxy), halo (chloro, bromo or iodo), oximino (as from 3-10 carbons), imidazolyl, or N-lactamyl. Representative such oximino groups for R'' include cyclohexanone oximino, methyl ethyl ketone oxime and benzaldehyde oximino, attached to the triazine ring through the oxygen as in: When R'' is imidazolyl, the corresponding structure would be Preferred R'' substituents are chloro, bromo, caprolactamyl and phenoxy, with chloro and caprolactamyl being most preferred. The non-reactive substituent R' may be alkyl, aryl, dialkylamino or diarylamino, with dialkylamino being preferred. Each alkyl may be of 1-6 carbons, and is preferably methyl or ethyl in the dialkylamino (dimethylamino, diethylamino or methylethylamino). Such co-catalyst/coupling agents can be readily prepared, if not commercially available, from starting materials such as cyanuric chloride, using available reactants. Thus, preferred cocatalyst/coupling agents with R'' as chloro and R' as dialkylamino can be prepared by reacting cyanuric chloride with dimethylamine or diethylamine in the presence of a suitable acid acceptor, and (if desired) isolating the desired mono(dialkylamino)dichloro-sym-triazine from the monofunctional di(dialkylamino)monochloro-sym-triazine. Small amounts of the latter compound may, however, be left in the co-catalyst/coupling agent as a polymer end-group. Examples of such preparative processes are described in US-A-3867383 (Example 1); Pearlman et al., J. Am. Chem. Soc., Vol. 70, pp. 3726-28 (1948). To prepare co-catalyst/coupling agents with R'' as lactamyl, a compound with R'' being chloro is reacted with a source of lactamyl anions (e.g., sodium or potassium caprolactam) or a lactam and an acid acceptor (e.g., caprolactam and triethylamine). If the R'' = chloro co-catalyst/coupling agent is used, the reaction with lactamyl anions will occur in situ. Conducting this reaction in advance has the advantage of reducing the induction period for polymerization, which enables shorter cycle times for reaction injection molding. A slightly less preferred group of co-catalyst/coupling agents are those of formula IVa with three reactive R'' groups. R'' may be any of the substituents described above for formula IIIa, but is preferably phenoxy or caprolactamyl. It is contemplated to use co-catalyst/coupling agents with different R'' moieties, such as are obtained by reacting cyanuric chloride with less than three molar equivalents of sodium phenoxide or bromomagnesium caprolactam, or with mixtures of the two totalling three molar equivalents. Cyanuric chloride itself is somewhat less preferred, because it causes a potential side reaction with the polyol, nucleophilic internal displacement (SN i ) reaction, known to take place with simple alcohols, in which -OH is replaced by -Cl. This side reaction results in the formation of cyanuric acid and alkyl chlorides with simple alcohols, see J. Org. Chem., Vol. 35, pp. 3967-68; in the present process the product would be cyanuric acid and chloro-terminated polyethers. The latter can react irreversibly with the catalyst, forming a lactam-terminated polyether which is inert toward further polymerization. Thus, the side reaction would inactivate both catalyst and co-catalyst, causing retardation or termination of polymerization. This side reaction can occur whenever R'' is chloro in formula IIIa or IVa. In general, when the block copolymer has segments of formulae I, II and III, it is preferred that the total segment III constitute 0.5-5 weight % of the polymer and that the total of segment II constitute 5-15 weight % (and more preferably 7-10 weight %) of the polymer. When the block copolymer has segments I, II and IV, it is generally preferred that the total segment IV constitute 0.5-5 weight % of the polymer and that the total segment II constitute 5-20 weight % (and more preferably 10-15 weight %) of the polymer. Lower amounts of segment II within the above ranges are preferred when R'' is Cl in formulae IIIa or IVa for the process of making the block copolymer. While Applicants do not wish to be tied to a particular theory of reaction mechanism, the following explanation is intended to explain how reactant proportions are selected and how the parts of the block copolymer are believed to be arranged. At a site on the co-catalyst/coupling agent, a lactamyl moiety will either be present or be attached in situ as follows: This reactive site may react with polypropylene oxide HO(R-O) 2p H where R is 1,2-propylene and 2p is the number of repeating units either to form plus lactam or to form The right end of formula V can react with catalyst to add first a lactamoyl moiety and eventually a string of aminoalkyleneacyl moieties, such that it becomes Esterification with the free hydroxyl of formulae VI will terminate the polyamide growth to form a chain Similar termination of the chain can occur by esterification with the free hydroxyl of formula VII or a free hydroxyl of the original polypropylene oxide. Similarly reactions with a caprolactamyl triazine such as those forming groups VI and VII can occur with the free hydroxyl of either VI or VII rather than the unreacted polyether. To further complicate matters, some reaction by catalyst at the nitrogen (e.g., the lactam nitrogen in formula V or Va) can occur, leading to a branch point from which two polyamide chains may grow. Based upon these mechanisms, it is necessary to use more catalyst for the process than the non-lactamyl R'' groups on the co-catalyst/coupling agents. For example, with 2-dimethylamino-4,6-dichloro-sym-triazine as co-catalyst/coupling agent, a molar ratio of 2:1 catalyst: co-catalyst could (in theory) be totally consumed making the active sites of formula V, with no catalyst left for polymerization (formula V to Va). Accordingly, molar ratios of at least 2.5:1 are preferred, and molar ratio between 3:1 and 5:1 are more preferred. For triphenoxy-sym-triazine, a 3:1 molar ratio could (in theory) be totally consumed making active sites: therefore a molar ratio of at least 4:1 is preferred, and molar ratios between 4.5:1 and 7.5:1 are more preferred. To the extent R'' is lactamyl, the proportion of catalyst required may be reduced, such that the more preferred ratio of catalyst: 2-dimethylamino-4,6-bis(caprolactamoyl)-sym-triazine becomes 1:1 to 3:1 instead of 3:1 to 5:1 for 2-dimethylamino-4,6-dichloro-sym-triazine. So long as the catalyst is in excess (as disclosed in the preceding paragraph), the ratio of hydroxyls of the polypropylene oxide to reactive ends R'' of the co-catalyst is believed to determine the distribution of polyether blocks. The difference in total concentration of reactive ends R'' and hydroxyls of the polyol (remaining R'' available for polyamide chain growth) will determine the polyamide chain length, and thus the total polymer size. It can be seen from the preceding discussion that the relationship between R'' and free hydroxyls has an effect on polyamide block size and polymer size. The total proportion of polyether and polyamide blocks, and their sizes, is believed to have a direct effect on the impact properties of parts made from the block copolymer. While, as with the block copolymers of US-A 4031164 impact strength increases with increasing proportion of polyol, excellent impact properties can be obtained in the present block copolymers with less than 18% polyol, with between 5 and 15% polyether (segment II), by weight, being most preferred. Examples 1 and 2 show the outstanding properties obtainable with such low polyether levels. Furthermore, with less polyether, the properties of polyamides, such as flexural modulus and heat resistance, are retained in a greater degree than for block copolymers having 18% or more polyether on a weight basis. EXAMPLES Materials and Methods Commercial caprolactam (dry grade) of less than 100 ppm water content was employed. Catalyst solutions designated as Solution A consisted of bromomagnesium caprolactam of known concentration in molten caprolactam and was prepared as described in Example 1. Examples of triazine co-catalyst/coupling agents employed were 2,4,6-triphenoxy-1,3,5-triazine (TPT) and 2-dimethylamino 4,6-dichloro-1,3,5-triazine (DADCT). DADCT was synthesized and purified by a procedure similar to that described in U.S. Patent 3,867,383. Co-catalyst solution, designated as solution B, consisted of monomer, impact modifier (a polyether polyol) and the co-catalyst/coupling agent. For polymerizations, a twin barrel stainless steel syringe-type laboratory RIM equipment was used (see Example 1). The polymers were isolated in the form of 6" x 6" x 1/8" (15 cm x 15 cm x 0.32 cm) or 6" x 8" x 1/8" (15 cm x 20 cm x 0.32 cm) plaques and were cut into various test specimens for mechanical testing. The plaques were normally tested in dry condition and tested according to ASTM procedures. The mechanical properties, particularly the impact strength, modulus and heat sag properties are related to the crystallinity as well as morphology of polyether and nylon 6 blocks in the amorphous phase. Crystallinity determination by X-ray diffraction Nylon RIM samples were analyzed by Phillips X-ray diffractometer, parafocus mode at 2ϑ = 6°-36°, CuKα radiation). The amorphous background was centered at about 22°, half with about 9.2°. In routine analysis the α and α phases are identified as follows - α form has two equatorial reflections α1 (200) and α2 (002 + 202); α1 usually occurs between 20.0° and 20.6° 2ϑ, and α2 between 22.6° and 24.0° 2ϑ. γform has an intense equatorial reflection γ1 (001) between 21.1° and 21.5° 2 ϑ, and a shoulder between 21.9° and 23.0°, γ2 (201 + 201). Also, the presence of γ form is confirmed independently by the meridional 110 reflection; this is intense if γ phase is present, and very weak if only α as present. In an unoriented sample-equatorial and meridonal patterns cannot be distinguished, but still the interpretation remains unchanged. Relative ratios of α and γ forms in unoriented samples can therefore be determined by comparing the areas under various peaks. Morphology - optical and transmission electron microscopy techniques Polarizing optical microscope was used to determine the spherulite morphology of nylon RIM samples. For the examination of the polyether and nylon block domains in the amorphous phase, transmission electron microscopy was employed. The samples were cross-sectioned at -80°C. The sections were stained with 0.25% phosphotungstic acid in a 50:50 mixture of water and ethyl alcohol and then rinsed in water. Phosphotungstic acid is an electron dense stain which reacts with available cationic groups of the nylon component. Therefore the electron dense (dark) area of the micrographs represent nylon-rich areas. Examples 1-4 The procedure described below for Example 2 was followed for four examples, as shown in Tables I and II, following Example 2. Example 2 The catalyst solution A was prepared by the dropwise addition of 100 mL of 2.9N ethyl magnesium bromide - diethyl ether solution to 0.5 L of dry (<100 ppm H₂0) caprolactam at 110°C, with stirring, under a dry nitrogen atmosphere. The addition took about one hour and after stirring an additional 15 minutes, vacuum was gradually applied and maintained at 1 mm Hg (133 Pa) for 20 minutes to remove the last traces of ether and ethane. The nitrogen atmosphere was re-introduced and a 10 mL aliquot of the solution was assayed by titration with 0.1 normal HCl to a phenolphthalein end-point. The normality was then adjusted to 0.6426N by dilution with a calculated amount of additional lactam. Thirty-two mL of this stock solution was then transferred by a pre-heated hypodermic syringe to a mixing tube mounted in a 135°C oil bath and maintained under a dry nitrogen atmosphere. Thirty-two mL of dry molten monomer was then added to the mixing tube and mixed with the stock catalyst solution by repeatedly withdrawing the solution into the hypodermic syrings. A 60 mL aliquot (19.28 mmol) of this solution was then withdrawn and added to the "A" barrel of a twin-barrel, heat jacketed, stainless steel syringe used for the mixing of "A" and "B" streams and filling the mold. The "A" solution was maintained in the barrel at 135°C under dry nitrogen. In this experiment the co-catalyst ("B") solution consisted of (a) caprolactam, (b) the impact modifier, Niax® PPG 4025 (a polypropylene glycol from Union Carbide Corporation), and (c) DADCT. A stock solution containing 36 wt.% PPG 4025 in dry caprolactam was prepared. The moisture content of the polypropylene glycol had previously been reduced to 154 ppm water by vacuum stripping for 20 hours at 100°C and 1 mm Hg (133 Pa). A 32.0 mL aliquot of this solution was mixed, as previously described, with a freshly prepared solution of 1.39 g of co-catalyst in 32.0 mL of caprolactam. A 60.0 mL aliquot of this solution, containing 13.49 milliequivalents of co-catalyst and 5.40 milliequivalents OH groups was transferred to barrel "B" of the twin-barrel syringe and maintained under dry nitrogen at 135°C. (See Table I for initial conpositions). The "A" and "B" solutions were then simultaneously discharged via two 1/8" (0.32 cm) outside diameter stainless steel tubes into a 1/8" (0.32 cm stainless steel) Swagelok tee, wherein they impingement mixed and discharged via a 1/8" (0.32 cm) outside diameter by 2" (5.1 cm) stainless steel hypodermic needle into a 160°C aluminum mold having a 6" x 6" x 1/8" (15 cm x 15 cm x 0.32 cm) cavity. The polymerization proceeded while maintaining the mold at 160°C; and, after 4 minutes, a slightly colored, rigid plaque completely filling the mold cavity was removed. Its properties are listed under Example 2 in Table II. Additional co-polymer plaques containing various concentrations of impact modifier are described in examples in Tables I and II. The tests used for measuring properties reported in Table II were as follows: A) Notched Izod by ASTM D-256, B) Heat Sag -- cantilever heat sag test on a 15.2 cm x 2.54 cm x 0.32 cm bar with 5 cm clamp support and 10.2 cm overhang at 120-121°C for one hour - value reported is the vertical displacement of the free end, C) ASTM D-790, D) Soxhlet extraction, 24 hours at room temperature, E) Reduced viscosity in m-cresol (concentration = 0.5%) F) by x-ray crystallography, G) by dynamic mechanical analyzer with ratios determined by fixing value at 70°C as 1. Nylon-6 Polyether block copolymer RIM polymerization with 2,4,6-triphenoxy-1,3,5-triazine (TPT) as co-catalyst/coupling agent Example 5 A solution of 29.95 g of polypropylene glycol, molecular weight 4000 and 5.247 g of triphenoxytriazine in caprolactam was vacuum stripped so that the final weight of caprolactam was 67.79 g. At the same time a solution of bromomagnesium caprolactam was prepared from a mixture of 20.6 mL of ethyl magnesium bromide, 2.0 molar in ethyl ether, and 104.74 q of caprolactam. Fifty mL aliquots of each solution at 135°C were injected simultaneously throuqh a single nozzle into a mold heated at 160°C. The mold was 7" x 7" x 1/8" (17,8 cm x 17.8 cm x 0.32 cm). After four minutes, the resulting plaque was removed. The composition was 1.30 equivalents of diol to 100 equivalents of caprolactam to 2.97 equivalents of triphenoxy-triazine to 4.11 equivalents of bromomagnesium caprolactam with 17.7% by weight of diol. The notched IZOD impact (by ASTM D-256, condition dry) in foot-pounds with a four pound (1.8 kg) loading was 18.2 (99.2 kg-cm/cm) at 23°C, and 4.1 (22.3 kg-cm/cm) at -29°C, all with partial breaks. The specimens were mold dry. The polymerizations were repeated under various conditions as shown in Table III.

Claims: Impact modified polyamide/polyether block copolymer having segments of formulae I, polypropylene oxide segments (II), the molecular weight of each segment II being from 500 to 5000; and either III or IV or both III and IV; with n being an integer of 3-12; m being a number different for individual segments, from 1 to 150; and R' being a monofunctional moiety inert during polymerization, selected from alkyl, aryl, dialkylamino, and diarylamino; with the triazine rings of segments III and IV being bonded only to the amino of segment I or either oxy of segment II, the terminal carbonyl of segment I being bonded only by either oxy of segment II or to a terminal -OH or the terminal -NH- of segment I being bonded only to the triazine ring of segment III or IV; the total segment I constituting between 55 and 98 weight % of the polymer and the total segment II constituting between 1 and 40 weight % of the polymer. A block copolymer according to claim 1 characterized in that n is 5. A block copolymer according to either of claims 1 and 2 characterized by having segments of formulae I, II and III, with the total of segment III constituting 0.5 to 5 weight % of the polymer, and the total of segment II constituting 5 to 15 weight % of the polymer. A block copolymer according to claim 3 characterized in that R' is dialkylamino. A block copolymer according to either of claims 1 and 2 characterized by having segments of formulae I, II and IV, with the total of segment IV constituting 0.5 to 5 weight % of the polymer, and the total of segment II constituting 5 to 20 weight % of the polymer. A method for the formation of impact-modified polyamide block copolymers according to claim 1 characterized by reacting: (a) a cyclic lactam of the formula: wherein n has the meaning given in claim 1; (b) polypropylene oxide having a molecular weight from 500 to 5000, (c) a catalyst selected from alkali metal hydrides, alkali metals, alkyl alkaline earth monohalides and aryl alkaline earth monohalides or a lactam salt of the formula where M+ is an alkali metal cation or an alkaline earth metal monohalide cation; and (d) a triazine co-catalyst/coupling agent selected from and mixtures thereof, wherein R'' is a reactive substituent selected, independently at each occurrence, from alkoxy, aryloxy, halo, oximino, imidazolyl and N-lactamyl and R' has the meaning given in claim 1, the polyether being reacted in an amount between 1 and 40 percent of the total reactants. A method according to claim 6 characterized in that n is 5. A method according to either of claims 6 and 7 characterized in that M⁺ is MgBr⁺. A method according to any one of claims 6 to 8 characterized in that the triazine co-catalyst/coupling agent has formula IIIa. A method according to claim 11 characterized in that R' is dialkylamino. A method according to any one of claims 6 to 10 characterized by mixing two solutions, with the catalyst being contained in the first solution, and the triazine co-catalyst/coupling agent being contained in the second solution. A method according to claim 11 characterized in that the first solution contains a first portion of cyclic lactam and the catalyst, and the second solution contains a second portion of the cyclic lactam, the triazine co-catalyst/coupling agent and the polyether. A method according to claim 11 or 12 characterized in that the two solutions are mixed and injected into a mold maintained at sufficient temperature to cause polymerization into a shaped article of the impact-modified block copolymer.

Inventors: AKKAPEDDI, MURALI KRISHNA
Applicants: ALLIED-SIGNAL INC.
Application year: 1984
Main classification: C08G69
IPC codes: C08G69, C08G73