PROCESS FOR PREPARING POLYMER OF FORMALDEHYDE

Abstract: A polymer or copolymer of formaldehyde is obtained by polymerizing formaldehyde and an optional co-monomer in the presence of a catalytically effective amount of a metal complex obtained between tetraphenylporphyrin or a derivative thereof and an organic metal compound.

Description: The present invention relates to a method of producing polymers with formaldehyde as a con­ stituent unit. Statement of Prior Arts Various methods of producing polymers with formaldehyde as a constituent unit have been known. They are generally described in the Plastic Materials Lecture, Vol. 13 "Polyacetal Resin" written by Matsushima and the like. Since polymers with formaldehyde as a consitituent unit are superior in mechanical properties, they have been widely used but the reaction is difficult to artifically control, the produced polymers have a wide molecular weight distribution, and the arrange­ ment of blocks in block copolymers is remarkably difficult to control, due to a remarkably high reactivity of formaldehyde. Japanese patent publication A (unexamined) No. 57-8223 teaches a process for preparing a block copolymer of two alkylene oxides in the presence of a complex catalyst comprising tetra-phenyl porphyrin and an organic aluminum compound. Summary of the Invention The present inventors investigated hard with paying attention to the matter that if the reaction of polymers with formaldehyde as a constituent unit can be controlled, mechanical properties of polymers can be controlled, whereby achieving a remarkably wide application. As a result, the present invention was achieved by finding that if a complex, which is obtained by a reaction between tetra­ phenylporphyrin or derivatives thereof and organo­ metal compounds, is used as a catalyzer in the polymerization of polymers with formaldehyde as a constituent unit, the produced polymers have a narrowed molecular weight distribution and also the arrangement of blocks in block copolymers can be optionally designed. That is to say, the present invention relates to a method of producing polymers with formal­ dehyde as a constituent unit, characterized by that a complex, which is obtained by a reaction between tetraphenylporphyrin or derivatives thereof and organometal compounds, is used as a catalyzer. A polymer or copolymer of formaldehyde is obtained by the step of polymerizing formaldehyde and an optional co-monomer in the presence of a catalytically effective amount of a metal complex obtained between tetraphenylporphyrin or a derivative thereof and an organic metal compound. The compound is preferably a compound of a divalent or trivalent metal such as zinc, magnesium and aluminum. The co-monomer is selected from an alkylene oxide, a lactone compound, a cyclic anhydride of a carboxylic acid and carbon dioxide. It is posssible in the invention that the co­ monomer(s) is added to the reaction system to obtain a block copolymer being controlled in the order of the blocks. It is preferable in the practical point of view that the polymerization is effected in an organic solvent in the atmosphere of an inert gas in the absence of water. It is preferable that formaldehyde forms the major part, 50 percent by weight or larger, of the obtained copolymer and formaldehyde is contained in the copolymer in an amount of at least 1 percent by weight. Tetraphenylporphyrin or derivatives thereof are obtained by a reaction between benzaldehyde or derivatives thereof and pyrrole. Compounds of metals having a valence of 2 or 3 are preferably used as organometal compounds in the present invention. For example, compounds of metals usch as zinc, magnesium and aluminium are preferably used, in particular preferably organoaluminium compounds. Concretely speaking, diethylaluminium chloride and triethylaluminium are shown. In the latter case, compounds having an activated hydrogen as an anionic species such as compounds of alcohol, carboxylic acid, phenol and sulfonic acid may be additionally used. Usual ligands can be used as a complex catalyzer in the present invention. These ligands include tertiary amines, phosphines, phosphites, thiazolium and the like. Above all, imidazol derivatives are particularly preferable. The use of these ligands leads to a further narrowed molecular weight distribution. Ligands can be added at a ratio of 0.1 to 3.0 moles based on 1 mole of metal porphyrin, preferably 0.5 to 2.0 moles, and in particular preferably 0.8 to 1.5 moles. Polymers with formaldehyde as a constituent unit used in the present invention include homo­ polymers or copolymers of formaldehyde and con­ stituent units other than formaldehyde in copolymers with formaldehyde as a constituent unit are at least one kind of compound selected from the group consisting of alkylene oxide, lactone, cyclic carboxylic acid anhydride and carbon dioxide, preferably alkylene oxides, and in particular preferably compounds of C₉ or less having an epoxy ring represented by the following general formula (I) or (II): (wherein R₁ - R₈ are hydrogen atom or hydrocarbon radical; any two of R₁ - R₄ may be in a continuous ring construction). Of these compounds ethylene oxide is in particular preferable. Molecular formaldehyde, which is obtained by the decomposition of paraformaldehyde, trioxane and the like, is preferably used as formaldehyde used in the present invention. It can be used in the gaseous form or the liquid form. In either case formaldehyde is necessary to dry in the usual manner. Solvents used in the present invention include hydrocarbons such as benzene, toluene and xylene and halogenated hydrocarbons such as chlorinated methylene, chloroform and dichlorethane. The polymerization in the present invention is carried out by the polymerization between formaldehyde and a complex catalyzer, which is obtained by a reaction between tetraphenylporphyrin or derivatives thereof in the presence of solvents under an inert gas atmosphere, or by obtaining a prepolymer by adding at least one kind of compound selected from the group consisting of alkylene oxide, lactone, cyclic carboxylic acid anhydride and carbon dioxide and then adding formaldehyde to the resulting prepolymer without delay. It is also possible by repeating the above described reaction to increase a number of blocks. Since ti is possible to control a quantity of constituent units to be used and a number of repeated times, the block length and the number of repeated blocks can be optionally designed. A ratio of block monomers in blockcopolymers can be optionally selected. Polymers obtained according to the present invention show a narrowed molecular weight dis­ tribution and copolymers containing an intended repeated unit construction can be obtained. A method of producing polymers with formal­ dehyde as a constituent unit according to the present invention can be used also as a method of producing oligomers having a remarkably low polymerization degree. Polymers and oligomers obtained according to the present invention can be used as materials for surface active agents, dispersion dyes, poly­ urethane and the like. In addition, they can be used as materials for setting paints and resists. Also they can be used as standard samples for measuring molecular weights and molecular weight distributions of other compounds. (Preferred Embodiments) The present invention is below roughly described with reference to the preferred embodiments but the scope of the present invention is not limited by these preferred embodiments. Example 1 Benzaldehyde of 80 ml (84.8 g) and pyrole of 56 ml (53.6 g) were put in propionic acid of 3 liters. The resulting mixture was subjected to a reaction under reflux for 30 min. and then left still for twenty-four hours. The reaction mixture was filtrated and then a sediment was recrystallized from a methanol-chloroform solvent mixture to obtain α, β, γ, δ-tetraphenylporphyrin at yield of 20%. A catalyzer solution of 20 ml containing a complex catalyzer of 0.68 g therein was prepared by a reaction between diethylaluminium chloride of 0.12 g and α, β, γ, δ-tetraphenylporphyrin of 0.61 g at room temperature in the presence of methylene chloride solvent of 20 ml under a dry nitrogen atmosphere. An additional methylene chloride solvent of 20 ml was added to the tetraphenylporphyrin complex catalyzer solution of 20 ml and then a solution of dry liquid formaldehyde in methylene chloride was put in the resulting mixture within 3 days in a divided manner. The resulting mixture was subjected to a polymerization reaction at room temperature under a nitrogen atmosphere. After stopping the polymerization reaction the reaction products were separated by the filtration and then subjected to an end acetylation. The reaction products were tested on the molecular weight distribution and a melting point. The results are shown in Table 1. Example 2 Methylene chloride of 20 ml as a solvent was added to a complex catalyzer of 1 mmol obtained in the same manner as in Example 1. Purified ethylene oxide of 15 mmol was added to the resulting mixture. The resulting mixture was subjected to a reaction for 24 hours at room temperature under a nitrogen atmosphere and immediately liquid formal­ dehyde was added in the same manner as in Example 1. Subsequently, ethylene oxide of 15 mmol was added again and then the resulting mixture was subjected to a reaction for 24 hours. After polymerization, the reaction products were tested in the same manner as in Example with the results as shown in Table 1. The composition ratio of blocks was calculated from a value of NMR. Example 3 Block copolymers were produced in the same manner as in Example 2 excepting that the ethylene oxide of 30 mmol was used in both the first time and the second time. After polymerization, the reaction products were tested in the same manner as in Example 1 with the results as shown in Table 1. Example 4 Vapourized formaldehyde was introduced into a complex solution obtained in the same manner as in Example 1 and the resulting mixture was subjected to a reaction. After polymerization, the reaction products were tested on the molecular weight distribution and a melting point with the results as shown in Table 1. Example 5 l-methylimidazol of 1.2 mmol was added to a solution containing a complex catalyzer of 1 mmol obtained in the same manner as in Example 1 and the resulting mixture was subjected to a reaction for 3 hours. Subsequently, the reaction mixture was subjected to a polymerization reaction in the same manner as in Example 1. After polymerization, the reaction products were tested on the molecular weight distribution and a melting point in the same manner as in Example 1 with the results as shown in Table 1. Comparative Example 1 Dry trioxane of 97 parts by weight, ethylene oxide of 3 parts by weight and methylal of 0.3 parts by weight as a molecular-weight controlling agent were put in an autoclave made of stainless steel. The mixture was subjected to a polymerization reaction in the presence of BF₃ as a catalyzer at 80°C under a nitrogen atmosphere. The resulting polymers and a melting point in the same manner as in Example 1 with the results as shown in Table 1.

Claims: 1. A process for preparing a polymer or copolymer of formaldehyde, which comprises the step of polymerizing formaldehyde and an optional co-monomer in the presence of a catalytically effective amount of a metal complex obtained between tetraphenylporphyrin or a derivative thereof and an organic metal compound. 2. A process as claimed in Claim 1, in which said compound is a compound of a divalent or trivalent metal. 3. A process as claimed in Claim 1, in which said compound is a compound of zinc, magnesium or aluminum. 4. A process as claimed in Claim 1, in which said co-monomer is selected from an alkylene oxide, a lactone compound, a cyclic anhydride of a carboxylic acid and carbon dioxide. 5. A process as claimed in Claim 1, in which the co­ monomer(s) is added to the reaction system to obtain a block copolymer being controlled in the order of the blocks. 6. A process as claimed in Claim 1, in which said copolymer is a copolymer of formaldehyde and an alkylene oxide having an epoxy group containing 9 or less carbon atoms. 7. A process as claimed in Claim 1, in which the polymerization is effected in an organic solvent in the atmosphere of an inert gas in the absence of water.

Inventors: HIJIKATA, KENJI, INOUE, SHOHEI, KAGEYAMA, YUKIHIKO
Applicants: POLYPLASTICS CO. LTD.
Application year: 1986
Main classification: C08G2
IPC codes: C08G2