Abstract: Alkylene oxide polymerizations are performed in the presence of a double metal cyanide polymerization catalyst and certain magnesium, Group 3-Group 15 metal or lanthanide series metal compounds. The presence of the magnesium, Group 3-Group 15 metal or lanthanide series metal compound provides several benefits including more rapid catalyst activation, faster polymerization rates and the reduction in the amount of ultra high molecular weight polymers that are formed. The catalyst mixture is unexpectedly useful in making polyethers having low equivalent weights.

Abstract: A hyperbranched polyether polyol obtained by a ring-opening reaction between a hydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2), wherein the polyether polyol includes a primary hydroxyl group (H1) and a secondary hydroxyl group (H2) in the molecular structure thereof, and has a number average molecular weight (Mn) of 1,000 to 4,000 and a hydroxyl value of 150 to 350 mg·KOH/g.

Abstract: A method for ionic polymerization of ethylene oxide. In the first step of the method, a gaseous monomer composition comprising ethylene oxide at a first flow rate is mixed with a gaseous ionic polymerization initiator at a second flow rate, thereby forming a mixture. The formed mixture is then heated with at least one heated filament to thereby form at least one polymer. The method may also be employed to coat a variety of different substrates in situ during the polymerization reaction.

Abstract: The present invention provides a highly efficient process for manufacturing copolyether glycol having a mean molecular weight of from about 650 to about 5000 dalton by polymerization of tetrahydrofuran and at least one alkylene oxide in the presence of an acid catalyst and at least one compound containing reactive hydrogen atoms. More particularly, the invention relates to a process for manufacturing copolyether glycol which comprises recycle to the polymerization reaction step of at least a portion of the oligomeric cyclic ether which is co-produced with the copolyether glycol, said process exhibiting an Space Time Yield value of greater than about 0.9.

Abstract: It is an object to provide a film having both high transparency and high heat resistance, and particularly a coating solution for forming a coating film from which an optical film can be produced. A triaroylbenzene-skeleton polymer in which a terminal of a polymer produced by polymerizing a compound of Formula [1] below is modified by a compound of Formula [2] below. A coating solution for forming a coating film, comprising the polymer. A film obtained from the coating solution for forming a coating film. In the formulae below, X1 is a divalent group of Formula [1a], Formula [1b], or Formula [1c] below (where Y1 and Y2 are independently a C1-2 alkylene group; n is an integer of 1 to 6; and m is an integer of 1 to 6), X2 is divalent benzene, thiophene, furan, or fluorine, and X3 is a hydrogen atom, a halogen atom, CF3, a C1-6 alkoxy group, or a C1-6 alkyl group.

Abstract: The present invention relates to an improved process for manufacturing polyether and copolyether glycols by polymerization of a reaction mixture comprising at least one tetrahydrofuran or at least one tetrahydrofuran and at least one other cyclic ether, for example, an alkylene oxide, in the presence of a particular perfluorosulfonic acid resin catalyst comprising a copolymer of tetrafluoroethylene (TFE) or chlorotrifluoroethylene (CTFE) and a monomer of the formula CF2?CF—O—CF2—CF2—SO2F.

Abstract: The present invention relates to the use of group 3 post-metallocene complexes based on sterically encumbered bis(naphthoxy)pyridine and bis(naphthoxy)thiophene ligands in the ring-opening polymerisation of polar monomers such as, for examples, lactones, lactides, cyclic carbonates.

Abstract: The present invention relates to a continuous process for manufacturing copolyether glycols with high incorporation of alkylene oxide by polymerization of tetrahydrofuran and at least one alkylene oxide in the presence of an acid catalyst, at least one compound containing reactive hydrogen atoms, and a specific diluent or solvent. More particularly, the invention relates to a diluent or solvent-assisted continuous process for manufacturing copolyether glycols with high incorporation of alkylene oxide.

Abstract: The present invention is directed at a binder for a battery electrode comprising an ethylene oxide-containing copolymer including a first monomer of ethylene oxide (EO) and at least one additional monomer selected from an alkylene-oxide that is different from the first monomer of EO, an alkyl glycidyl ether, or a combination thereof; wherein the ethylene oxide-containing copolymer has a weight average molecular weight less than about 200,000 g/mole (e.g., from about 10,000 to about 100,000), the molar fraction of the first monomer of EO (XEo) in the ethylene oxide-containing copolymer is greater than 0.80 (e.g., from about 0.80 to about 0.995), and the ethylene oxide-containing copolymer h a peak melting temperature (Tp), in ° C., for a selected XEO in the range of about 0.80 to about 0.995, which is below a maximum value of Tpmax, at the selected XEO, which is calculated using the equation Tpmax=(60?150 (1?XEO)).

Abstract: A method for ionic polymerization of ethylene oxide. In the first step of the method, a gaseous monomer composition comprising ethylene oxide at a first flow rate is mixed with a gaseous ionic polymerization initiator at a second flow rate, thereby forming a mixture. The formed mixture is then heated with at least one heated filament to thereby form at least one polymer. The method may also be employed to coat a variety of different substrates in situ during the polymerization reaction.

Abstract: A catalyst composition for polymerizing oxiranes is provided that yields high molecular weight poly(oxiranes). The catalyst composition comprises: a hydrophobically modified particulate inorganic oxide; an aluminum alkyl complex; and a compound containing a Lewis basic free electron pair. Polymerization methods and poly(oxirane) polymers are also provided.

Abstract: A catalyst, co-catalyst, and/or chain transfer agent is added at a time after initiation of an addition polymerization reaction to produce a polymer product with a widened molecular weight distribution relative to having all of the components in the original reaction mixture. The catalyst, co-catalyst, or chain transfer agent may be added discretely or continuously to the reaction to produce a product with a bimodal, trimodal, or other broadened molecular weight distribution.

Abstract: The present invention relates to a process for preparing polytetrahydrofuran or tetrahydrofuran copolymers by polymerization of tetrahydrofuran in the presence of a telogen and/or a comonomer over a fixed bed of an acid catalyst, in which the temperature of the polymerization mixture increases in the direction of flow through the catalyst bed.

Abstract: Mixtures or adducts of N-heterocyclic carbenes with metal amides or metal alkoxides are effective catalysts for the polymerization of macrocyclic polyester oligomers. The catalysts are stable at polymerization temperatures, and the polymerization is rapid, resulting in high monomer conversion, high molecular weight, and a mechanically sound material.

Abstract: The present invention relates to a solid, acid catalyst for the preparation of polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of these polymers by polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer, which has a BET surface area of at least 160 m2/g and an acid center density of at least 0.05 mmol/g for pKa values of from 1 to 6, to a process for preparing it and to a process for the polymerization of cyclic ethers over this catalyst.

Abstract: A cationically polymerizable composition containing a cationically polymerizable compound and a cationic polymerization initiator, wherein a total content of a cationic compound, a metal compound and a strong acid compound contained in the cationically polymerizable composition is in the range of 1 to 500 ppm by weight based on the total weight of the cationically polymerizable composition.

Abstract: The invention relates to two-component preparations comprising epoxy compounds and a noble metal species, in particular for the preparation of dental compositions. The invention particularly relates to two-component dental compositions which comprise epoxy compounds and are cured by cationic polymerization in the presence of a noble metal species.

Abstract: The present invention provides process for producing polyols using a crystalline, hydroxide containing double metal cyanide (DMC) catalyst of the formulae (I) or (II), M1x[M2(CN)6]yOH.L??(I) M1x[M2(CN)6]y.zM1(OH)q.L??(II) wherein M1 represents a metal selected from Zn+2, Fe+2, Ni+2, Mn+2, Co+2, Sn+2, Pb+2, Fe+3, Mo+4, Mo+6, Al+3, V+4, V+5, Sr+2, W+4, W+6, Cu+2 and Cr+3, M2 represents a metal selected from Fe+2, Fe+3, Co+2, Co+3, Cr+2, Cr+3, Mn+2, Mn+3, Ir+3, Ni+2, Rh+3, Ru+2, V+4 and V+5, L represents an organic ligand and x, y and q are chosen to maintain electroneutrality. The polyols of the present invention may find use in the preparation of polyurethanes.

Abstract: A 2-cyanoacrylate composition useful as an adhesive contains a Lewis acid metal salt comprising a metal such as aluminum, gallium, indium or thalium, and the conjugate base of an acid such as a monohalo-, dihalo- or trihalo-acetate (e.g. aluminum trifluoroacetate salt). A clathrate such as a crown ether is also present.

Abstract: This invention relates to a catalyst for producing aliphatic polycarbonate, which is composed of a rare-earth coordination compound; an alkyl metal compound; a polyol; and a carbonate. The catalytic efficiency of the catalyst of the present invention is more than 8×104 g polymer/mol RE(RE is rare earth metal). The number average molecular weight of the polymer is higher than 30,000. The degree of carbon dioxide fixation is more than 42 wt % and the content of alternative sequence structure exceeds 97%.

Abstract: A cationically polymerizable liquid composition is formed from a cationically polymerizable mixture (A) and a solid resin (B) that is compatible with the mixture (A) at room temperature and has a softening point of at least 40° C., so that the composition has a viscosity at 25° C. of 20 Pa·sec or below. The cationically polymerizable mixture (A) is formed from a monofunctional monomer (A-1) having in the molecule only one cyclic ether structure represented by formula (1) below, a polyfunctional monomer (A-2) having in the molecule at least two cyclic ether structures represented by formula (1) below, and a latent cationic polymerization initiator (A-3). A tacky polymer formed by cationic polymerization of the composition is also disclosed. (In formula (1), n denotes 0, 1, or 2, and R1 to R6 independently denote hydrogen atoms or hydrocarbon groups, which may have a substituent.

Abstract: Described is the use of nanoscale metal oxide particles as catalysts for the thermal and/or photochemical polymerization of species having at least one polymerizable carbon-carbon multiple bond and/or at least one carbon containing ring capable of undergoing a ring opening polymerization.

Abstract: The invention relates to double-metal cyanide (DMC) catalysts for preparing polyether polyols by the polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms, wherein the DMC catalysts are composed of: a) at least one DMC compound; b) at least one organic complexing ligand which is not a coronand; and c) at least one coronand. The DMC catalysts of the present invention have increased activity compared to known catalysts.

Abstract: This invention relates to crystallizing polyether polyols which can be produced firstly by the reaction of propylene oxide and polyhydroxy compounds in the presence of an alkoxy compound which contains zinc and/or aluminium atoms to form a crystallizing polyether polyol with an average molecular weight Mn from 500 to 5000, followed by the further reaction of the crystallizing polyether polyol which is thus obtained with 10 to 90% by weight, with respect to the amount of crystallizing polyol, of an epoxide in the presence of a catalyst which does not polymerize propylene oxide stereospecifically, to form a crystallizing polyether polyol with an average molecular weight Mn from 1000 to 20,000. The invention further relates to a method for the production thereof and to the use thereof for the production of polyurethane materials, particularly polyurethane foams, polyurethane elastomers and polyurethane coatings.

Abstract: A 2-cyanoacrylate composition useful as an adhesive contains a Lewis acid metal salt which comprises a specific metal such as aluminum, gallium, indium or thallium, and the conjugate base of an acid having oxygen such as a monohalo-, dihalo or trihaloacetate, wherein the metal is bonded to the conjugate base through an oxygen atom, and a compound having clathrating ability such as a crown ether.

Abstract: Polymerization catalysts of oxirane compounds are catalysts which are suitable to carry out suspension precipitation polymerization of the oxirane compounds in an organic solvent which cannot dissolve the polymers and comprise a reaction product of (A) an alkylaluminum compound, (B) an oxoacid compound of phosphorus having at least one OH group in its molecule and (C) a nitrogen-containing cyclic compound having pKa of 6 to 8. A process for preparing the polymers of the oxirane compounds is a process wherein the monomeric oxirane compounds are subjected to the suspension precipitation polymerization in the organic solvent which cannot dissolve the polymers in the presence of the catalysts to prepare the polymers of the oxirane compounds.

Abstract: The present invention relates to a process for the preparation of novel, partially crystalline polyether polyols with a functionality of ≧2, an average molecular weight Mn of 500 to 100,000 and a molar proportion of isotactic triads determining the crystallinity of >28%. The new polyether polyols are prepared by polymerizing alkylene oxides in the presence of a bimetallic :-oxoalkoxide modified with hydroxyl compounds.

Abstract: A curing catalyst comprising at least one of a cationic curing catalyst component and an organo-metallic compound component. At least one of these components is capable of reversibly repeating the dissolution and precipitation through heating and cooling. The cationic curing catalyst component includes in its molecule at least one substituted or unsubstituted hydrocarbon group having 10 or more carbon atoms, or at least one cyclic organic structure having a substituted or unsubstituted hydrocarbon group having 10 or more carbon atoms.

Abstract: Disclosed are a process for producing a poly(alkylene ether) glycol which comprises polymerizing a cyclic ether in the presence of at least a catalyst and a carboxylic acid anhydride, wherein the carboxylic acid anhydride has a ketene dimer content of 50 ppm or lower, and a process for producing a poly(alkylene ether) glycol which comprises polymerizing a cyclic ether in the presence of at least a catalyst and acetic anhydride, wherein the acetic anhydride is purified acetic anhydride obtained by treating acetic anhydride by contacting with at least one of a metal oxide and a mixed oxide, and optionally, distilling the acetic anhydride simultaneously with or after the contact treatment.

Abstract: A process for polymerizing cyclic ethers over a heterogeneous catalyst comprises using a heterogeneous catalyst comprising one or more pillared interlayered clays (PILCs).

Abstract: Novel compounds having one group 13 element bound with one mono- or di-anionic tridentate ligand, a method of preparation thereof and use thereof as a copolymerization catalyst.

Abstract: An improved process for Polytetramethylene-Ether-Glycol-Diesters of the formula R—CO—O(CH2—CH2—CH2—CH2—O)n-COR1, in which R and R1 are identical or different and are alkyl radicals or derivatives thereof, by polymerization of tetrahydrofuran in the presence of a heterogeneous polymerization catalyst and in the presence of a carboxylic anhydride. The use of aluminum silicate catalyst composed of acid-activated and calcinated natural halloysite instead of the known catalytic silicates as bentonite, zeolite or kaolinite. The new catalyst with a very long lifetime produces polymers having more uniform properties and narrow molecular weight distribution even with a relative impure monomer.

Abstract: Disclosed herein is a curing catalyst comprising at least one compound which is a substituted or unsubstituted aromatic or heteroaromatic compound and having any one of groups (I) --O--R.sub.1, (II) --O--CY--R.sub.1, or (III) --O--CY--X--R.sub.1, the groups being directly bonded to the armoatic or heteroaromatic ring, in a number of 1 to 10 wherein R.sub.1 may be the same or different and is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is O or NH and Y is O or S. Furthermore, an epoxy resin composition comprising the curing catalyst is disclosed.

Abstract: Provided is a compound having an oxetanyl group and represented by the following formula: ##STR1## wherein R.sub.1 represents a methyl group or an ethyl group and R.sub.2 represents a hydrogen atom, a halogen atom, a straight or branched chain alkyl group of 1-5 carbon atoms, an unsubstituted or substituted phenyl group, an unsubstituted or substituted phenoxymethyl group, an unsubstituted or substituted phenoxypropyl group or an unsubstituted or substituted phenyl group. A process for producing the compound and a curing composition comprising the compound and a cationic polymerization initiator are also provided.

Abstract: An impregnation resin composition comprising an alicyclic epoxy compound, an acid anhydride, an aluminum compound having an organic group, and butylglycidyl ether, wherein the alicyclic epoxy compound contains not more than 30 ppm in concentration of Na ion component.

Abstract: Synthesis of a vinyl terminated polymer by reacting a cationically polymerizable monomer in the form of a cyclic ether with an acid chloride in a suitable solvent and in the presence of a Lewis acid. The vinyl-terminated polymers can be polymerized with other appropriate monomers resulting in thermoplastic elastomers having suitable properties for use as binders for explosives and propellants.

Abstract: Disclosed is a process for copolymerization of formaldehyde with cyclic ethers in the presence of organic nitro compounds. The process enhances the selectivity for the cyclic copolymer.

Abstract: A thermal latent acid catalyst which comprises (i) a compound having an epoxy group, (ii) a compound having a sulfur atom of the following formula: R.sup.5 --S--R.sup.6, wherein R.sup.5 and R.sup.6 are the same or different from each other and are a hydrogen atom or an organic group of 1 to 40 carbon atoms, R.sup.5 and R.sup.6 optionally are bonded with each other to form a cyclic structure; and (iii) a Lewis acid of the following formula: (X.sup.1).sub.n1 --M.sup.1 --(R.sup.7).sub.n2, wherein M.sup.1 is a boron atom, an aluminium atom, a tin atom, a lead atom or a transition element, X.sup.1 is one or more halogen atoms, R.sup.7 is one or more organic groups of 1 to 40 carbon atoms, R.sup.7 optionally forms a chelate ring by coordinating to the M.sup.1 atom, n1 and n2 are each an integer of 0 through 6, and n1 plus n2 equals an integer of 1 to 6. The ratio of the epoxy group of the epoxy compound (i) to the M.sup.1 atom of the Lewis acid is 0.

Abstract: A process for the continuous and discontinuous production of tetrahydrofuran polymers by homopolymerizing tetrahydrofuran or copolymerizing tetrahydrofuran with 1,2-alkylene oxides in the presence of compounds with reactive hydrogen or carboxylic acid anhydrides on an acid-treated, calcined and granulated aluminium silicate catalyst which may consist of amorphous aluminium silicate, a zeolite or kaolin. By keeping the concentration of carboxylic acid anhydride or alkylene oxide constant below 1 wt. % in the polymerization recipe throughout the polymerization it is possible to largely prevent the formation of cyclic ethers and to obtain a polymer with a very narrow molecular weight distribution. In granular form, the catalysts exhibit a hitherto unknown activity and form polymers with a very narrow molecular weight distribution and low color and acid numbers.

Abstract: Disclosed herein is a curing catalyst comprising at least one compound which is a substituted or unsubstituted aromatic or heteroaromatic compound and having any one of groups (I) --O--R.sub.1, (II) --O--CY--R.sub.1, or (III) --O--CY--X--R.sub.1, the groups being directly bonded to the armoatic or heteroaromatic ring, in a number of 1 to 10 wherein R.sub.1 may be the same or different and is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is O or NH and Y is O or S. Furthermore, an epoxy resin composition comprising the curing catalyst is disclosed.

Abstract: A process for polymerizing oxiranes, oxetanes, oxepanes, dioxolanes, trioxanes, and tetrahydrofurans to their respective polymers by contacting them with a selected metal compound is disclosed; and also a process for depolymerizing polytetrahydrofurans to monomeric tetrahydrofurans by contacting the polymer with a selected metal compound at a temperature of about 100.degree. C. to about 250.degree. C. The catalysts may be in solution or part of a heterogeneous solid, and selected organic compounds are used as accelerators in the polymerizations. The polymeric products, some of which are novel, may be used as polyether monomers for further polymerization, as by reaction with isocyanates to produce polyurethanes, and other useful polymers. Some of the polymeric products are relatively high in molecular weight and are suitable for direct use, for instance as spandex fibers.

Abstract: A curable resin system in supercritical carbon dioxide as diluent includes an epoxy resin, a co-reactant selected from poly N-substituted aziridines, and a catalyst to promote cure at ambient temperature. The system is compatible with various epoxy resins such as bisphenol A epoxy, bisphenol F epoxy, novolac epoxy, cycloaliphatic epoxy, triglycidyl-aminophenol, and triglycidyl isocyanurate. The aziridine co-reactant may be selected from reaction products of NH aziridines with acrylates and methacrylates of trimethylolpropane, ethylene glycol, propylene glycol, bisphenol A, bisphenol F, pentaerythritol, glycerol, and their alkoxylated derivatives; reaction products of NH aziridines with epoxy compounds; and 1-aziridine ethanol and its reaction products with epoxy and isocyanate functional compounds. Suitable catalysts include acid salts and complexes, strong electron accepting compounds, combinations of silicon hydrides and metal complexes, and non-halogen containing boron derivatives.

Abstract: This invention relates to novel multifunctional oxetanes, i.e., compounds having multiple oxetane groups, which are useful as initiators in the preparation of star polymers and polymer cascades containing energetic groups. In addition, this invention relates to a process for the preparation of star polymers and polymer cascades, whereby novel multifunctional oxetanes act as initiators in the formation of theses polymers. The reaction of these initiators with various propagating, high-energy oxetanes, such as 3,3-bis-(azidomethyl)oxetane (BAMO) and 3-nitratomethyl-3-methyloxetane (NMMO), gives star polymers with varying molecular weights and functionalities. The star polymers and polymer cascades of the present invention are useful as binders in high-energy formulations.

Abstract: Polytetrahydrofuran or polytetrahydrofuran monoesters of C.sub.1 -C.sub.20 -monocarboxylic acids or polytetrahydrofuran monoethers of monohydric C.sub.1 -C.sub.20 -alcohols, having an average molecular weight of from 250 to 10,000 Dalton and liquid at room temperature, are prepared by the cationic polymerization of tetrahydrofuran in the presence of a telogen by a process in which tetrahydrofuran is polymerized in the presence of water, 1,4-butanediol and/or polytetrahydrofuran having an average molecular weight of from 200 to 700 Dalton and/or of a C.sub.1 -C.sub.20 -monocarboxylic acid and/or of a monohydric C.sub.1 -C.sub.20 -alcohol with the aid of a catalytic amount of a zeolite catalyst which has an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio of from 4:1 to 100:1 and in which the population ratio P of the acid centers on the external surface of the zeolite to the total number of acid centers of the zeolite is 0.03/l or more.

Abstract: A process for polymerizing oxepanes, dioxolanes, trioxanes, and tetrahydrofurans to their respective polymers by contacting them with a selected metal compound and an accelerator which is a selected vinyl ester or a selected phosphorous compound.

Abstract: The invention relates to a substantially solventless curable resin composition, in particular for the fabrication of prepregs, which contains more than 45% by weight of substances which are solid at ambient temperature at least or at lower temperature, and which, in addition to comprising customary modifiers, comprises solid epoxy resins or a mixture of liquid and solid epoxy resins, at least one initiator which is sensitive to UV radiation for the polymerisation of the epoxy resins and has the formula I ##STR1## wherein a and b are each independently of the other 1 or 2, R.sup.1 ist a .pi.-arene, R.sup.2 is a .pi.-arene, an indenyl anion or a cyclopentadienyl anion, [X].sup..crclbar. is an anion [LQ.sub.m ].sup..crclbar.

Abstract: When selected silicon compounds are added to cationic polymerizations of cyclic ethers such as oxiranes and tetrahydrofurans, the rate of polymerization is often increased, and novel polyethers are produced. The polyether products are useful as monomers and macromonomers, particularly after hydrolysis of silicon containing end groups.

Abstract: A poromeric material for maintaining an electrostatic charge is provided, the material including a matrix of fibers, a polymeric binder for binding the matrix, and electrets present substantially uniformly throughout the poromeric material. Also provided are methods for making the poromeric material. In one embodiment, a polymeric binder mixture having electrets substantially uniformly contained therein is formed. The matrix of fibers is impregnated with the mixture and cured, whereby the electrets are substantially uniformly distributed throughout the matrix to produce the electrostatic poromeric material. In an alternative embodiment, the electrets are contained in the fibers of the matrix. The poromeric material may be used to encase a core to form a roller, for example, a hickey-removing roller.

Abstract: This invention relates to novel multifunctional oxetanes, i.e., compounds having multiple oxetane groups, which are useful as initiators in the preparation of star polymers and polymer cascades containing energetic groups. In addition, this invention relates to a process for the preparation of star polymers and polymer cascades, whereby novel multifunctional oxetanes act as initiators in the formation of theses polymers. The reaction of these initiators with various propagating, high-energy oxetanes, such as 3,3-bis-(azidomethyl)oxetane (BAMO) and 3-nitratomethyl-3-methyloxetane (NMMO), gives star polymers with varying molecular weights and functionalities. The star polymers and polymer cascades of the present invention are useful as binders in high-energy formulations.

Abstract: Processes for producing a polyoxymethylene copolymer includes forming a crude polyoxymethylene copolymer by subjecting a reaction system containing trioxane, a cyclic ether or cyclic formal comonomer, and a catalyst (e.g., boron trifluoride or a coordination compound thereof) to copolymerization reaction conditions. During copolymerization, both the total content of impurities and catalyst in the copolymerization reaction system are adjusted. In this regard, the impurities content (i.e., those compounds which form unstable end groups in the polyoxymethylene copolymer and/or those compounds having a chain-terminating or chain-transfer function) in the copolymerization reaction system is adjusted to 1.times.10.sup.-2 mole percent or less based on the total monomer amount, while the the content of the catalyst in the copolymerization reaction system to between 1.times.10.sup.-3 to 1.times.10.sup.-2 mole percent based on the total monomer amount.