Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
  • C08G2/10—Polymerisation of cyclic oligomers of formaldehyde

Definitions

• the present invention relates to a method for producing a polyacetal copolymer.
• a known method for producing polyacetal copolymers is to cationic polymerize a main monomer (trioxane) and a comonomer copolymerizable with the main monomer in the presence of a cationic polymerization catalyst.
• Lewis acids such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, and antimony pentafluoride, as well as their complex compounds or salts, are commonly used as cationic polymerization catalysts.
• a polymerization catalyst such as boron trifluoride needs to be added in a relatively large amount (for example, 40 ppm or more relative to the total monomers) during polymerization. This makes it difficult to fully deactivate the catalyst remaining in the polyacetal copolymer after polymerization in the manufacturing process. Even if the catalyst can be deactivated, problems such as accelerated decomposition of the copolymer can occur due to catalyst-derived substances remaining in the copolymer.
• aqueous solution treatment liquid
• a basic compound such as triethylamine
• Patent Document 1 describes a method for producing a polyacetal copolymer, which includes a step of copolymerizing using a specific heteropolyacid as a polymerization catalyst, and a step of adding a specific salt or its hydrate to the obtained reaction product and melt-kneading the mixture to deactivate the polymerization catalyst.
• Patent Document 2 describes that polymerization stability can be obtained in industrial production by using a polymerization catalyst that is a mixture of a specific heteropolyacid and a specific heteropolyacid metal salt.
• Patent Document 1 by using a specific highly active heteropolyacid as a polymerization catalyst and melt-kneading it together with a deactivator, polymerization is possible with a small amount of catalyst, cumbersome processes can be eliminated, the amount of formaldehyde generated is extremely small, and a high-quality polyacetal copolymer can be obtained.
• the production volume of polyacetal resin was increased with a small amount of polymerization catalyst, a decrease in the polymerization yield of the polyacetal copolymer and variation in the quality of the polyacetal resin became apparent.
• Patent Document 2 by using a polymerization catalyst that is a mixture of a specific heteropolyacid and a specific metal salt of a heteropolyacid, the polymerization reaction can be stabilized and the resin quality can be improved by reducing the amount of formaldehyde generated.
• molded products made from the obtained polyacetal resin can have poor appearances, and there has been a demand for an improvement in this regard.
• the present invention was made in consideration of these points, and aims to provide a manufacturing method that can stably produce polyacetal copolymers, even in mass production, that not only reduces the amount of formaldehyde generated, but also has excellent flowability during molding and can be used to produce molded products with excellent appearance.
• a method for producing a polyacetal copolymer comprising copolymerizing trioxane and a comonomer copolymerizable with said trioxane in the presence of a polymerization catalyst, comprising the steps of:
• the polymerization catalyst is a heteropolyacid (A) represented by the following general formula (1) and a heteropolyacid salt (B) represented by the following general formula (2),
• the heteropolyacid (A) and the heteropolyacid salt (B) are used in combination.
• L is an alkali metal element
• M1 and N1 are each independently a central element of P or Si
• M2 and M3 are coordination elements of W, Mo, or V which may be the same or different
• N2 and N3 are coordination elements of W, Mo, or V which may be the same or different.
• at least one of M2 and M3 , and N2 and N3 consists of a different coordination element.
• p is an integer of 1 or more and 10 or less; q and r are positive integers; s is an integer of 10 or more and 100 or less; h is an integer of 1 or more; i is an integer of 0 or more and 50 or less; v is an integer of 1 or more and 10 or less; w and x are positive integers; y is an integer of 10 or more and 100 or less; j is an integer of 1 or more; and k is an integer of 0 or more and 50 or less.
• q+r is an integer of 6 or more and 40 or less;
• N2 and N3 are the same coordination element
• w+x is an integer of 6 or more and 40 or less.
• heteropolyacid (A) is at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid and silicomolybdotungstovanadic acid.
• heteropolyacid salt (B) is at least one selected from the group consisting of lithium phosphotungstate, sodium phosphotungstate, potassium phosphotungstate, sodium silicotungstate, sodium phosphomolybdate, and sodium phosphotungstovanadate.
• the present invention provides a manufacturing method that can not only reduce the amount of formaldehyde generated, but also stably mass-produce polyacetal copolymers that have excellent flowability during molding and can be used to produce molded products with excellent appearance.
• the method for producing a polyacetal copolymer according to one embodiment of the present invention is a method for producing a polyacetal copolymer by copolymerizing trioxane and a comonomer copolymerizable with the trioxane in the presence of a polymerization catalyst.
• a polymerization catalyst Each of the components will be described below.
• Trioxane is a cyclic trimer of formaldehyde. Trioxane according to one embodiment of the present invention is used as a main monomer.
• the main monomer refers to a monomer that is contained in the largest amount among all monomers.
• Trioxane is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acid catalyst, and is used after being purified by a method such as distillation.
• the comonomer according to one embodiment of the present invention is not particularly limited as long as it is copolymerizable with trioxane.
• the comonomer is preferably selected from the group consisting of cyclic ethers and cyclic formals having at least one carbon-carbon bond.
• Examples of comonomers include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin, etc.
• 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide are preferred from the viewpoint of polymerization stability.
• compounds having two polymerizable cyclic ether groups or cyclic formal groups such as diglycidyl ether of alkylene glycols, such as butanediol diglycidyl ether, and diformal, and compounds having three or more polymerizable cyclic ether groups or cyclic formal groups, such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether, can be used.
• diglycidyl ether of alkylene glycols such as butanediol diglycidyl ether, and diformal
• compounds having three or more polymerizable cyclic ether groups or cyclic formal groups such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether
• the content of the comonomer in one embodiment of the present invention is preferably 0.01 to 20 parts by mass, and more preferably 0.05 to 5 parts by mass, per 100 parts by mass of trioxane. If the content of the comonomer is 0.01 to 20 parts by mass per 100 parts by mass of trioxane, the polymerization can proceed stably and a decrease in the crystallization rate and degree of crystallization of the polymer chains can be suppressed.
• a polymerization catalyst according to one embodiment of the present invention is a heteropolyacid (A) represented by the following general formula (1) and a heteropolyacid salt (B) represented by the following general formula (2).
• the heteropolyacid (A) and the heteropolyacid salt (B) are used in combination.
• L is an alkali metal element, and the alkali metal element is preferably any one of lithium, sodium, and potassium.
• M 1 and N 1 are each independently a central element of P or Si
• M 2 and M 3 are coordination elements of W, Mo, or V which may be the same or different from each other
• N 2 and N 3 are coordination elements of W, Mo, or V which may be the same or different from each other.
• at least one of M 2 and M 3 and N 2 and N 3 is composed of a different coordination element.
• p is an integer of 1 or more and 10 or less.
• q and r are positive integers.
• s is an integer of 10 or more and 100 or less, and preferably an integer of 30 or more and 80 or less.
• h is an integer of 1 or more and preferably an integer of 1 or more and 10 or less.
• i is an integer of 0 or more and 50 or less, and preferably an integer of 30 to 50 or less.
• v is an integer of 1 or more and 10 or less.
• w and x are positive integers.
• y is an integer of 10 or more and 100 or less, preferably an integer of 30 or more and 80 or less.
• j is an integer of 1 or more and preferably an integer of 1 or more and 10 or less.
• k is an integer of 0 or more and 50 or less, preferably an integer of 30 or more and 50 or less.
• q+r is an integer of 6 or more and 40 or less, preferably an integer of 10 or more and 20 or less.
• w+x is an integer of 6 or more and 40 or less, preferably an integer of 10 or more and 20 or less.
• heteropolyacids (A) include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, silicomolybdotungstovanadic acid, etc.
• phosphotungstic acid, phosphomolybdotungstovanadic acid, and phosphotungstovanadic acid are preferred, and phosphotungstovanadic acid is more preferred.
• the heteropolyacid salt (B) is preferably a salt of an alkali metal.
• examples of such heteropolyacid salt (B) include lithium phosphotungstate, sodium phosphotungstate, potassium phosphotungstate, sodium silicotungstate, sodium phosphomolybdate, sodium phosphotungstovanadate, sodium silicotungstovanadate, etc. Of these, sodium phosphotungstate, sodium silicotungstate, sodium phosphomolybdate, and sodium phosphotungstovanadate are preferred.
• the heteropolyacid (A) and the heteropolyacid salt (B) are used in a mixture.
• combinations of the heteropolyacid (A) and the heteropolyacid salt (B) include phosphotungstovanadic acid and sodium phosphotungstate, phosphotungstovanadic acid and lithium phosphotungstate, phosphotungstovanadic acid and potassium phosphotungstate, phosphomolybdotungstovanadic acid and sodium phosphotungstate, phosphotungstovanadic acid and sodium silicotungstate, phosphotungstovanadic acid and sodium phosphomolybdate, and phosphotungstic acid and sodium phosphotungstovanadate.
• phosphotungstovanadic acid and sodium phosphotungstate phosphomolybdotungstovanadic acid and sodium phosphotungstate
• phosphotungstovanadic acid and sodium silicotungstate phosphotungstovanadic acid and sodium phosphomolybdate
• phosphotungstic acid and sodium phosphotungstovanadate are preferred.
• heteropolyacid (A) and heteropolyacid salt (B) By using a mixture of heteropolyacid (A) and heteropolyacid salt (B), it is possible to reduce the amount of formaldehyde generated, as well as to obtain a polyacetal copolymer that has excellent flowability during molding and can be used to produce molded products with excellent appearance.
• the mass ratio (B/A) of the heteropolyacid salt (B) to the heteropolyacid (A) is preferably 0.2 to 10, and more preferably 0.5 to 10.
• the mass ratio (B/A) is 0.2 to 10
• the flowability during molding is good, and the appearance of the molded product is also good.
• the content of the polymerization catalyst in one embodiment of the present invention is preferably 0.05 to 100 ppm, and more preferably 0.1 to 50 ppm, relative to the total amount of the above-mentioned monomers (trioxane and comonomer).
• the content of the polymerization catalyst may be changed as appropriate depending on the type of catalyst. Note that "ppm” stands for “mass/mass ppm.”
• the polymerization catalyst is preferably used after diluting with a solvent (hereinafter also referred to as "solvent") that is inactive to the polymerization reaction.
• solvent hereinafter also referred to as "solvent”
• concentration of the polymerization catalyst diluted with the solvent is preferably 0.05 to 30% by mass, more preferably 0.1 to 20% by mass, and even more preferably 0.5 to 10% by mass.
• concentration of the diluted polymerization catalyst is 0.05 to 30% by mass, the polymerization catalyst can be sufficiently diffused in the monomer, so that the polymerization reaction can be carried out uniformly.
• solvents examples include esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, and butyl acetate, and ketones such as acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, and methyl t-butyl ketone.
• esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, and butyl acetate
• ketones such as acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, and methyl t-butyl ketone.
• a known chain transfer agent for adjusting the degree of polymerization such as methylal or butyral
• a hindered phenol-based antioxidant such as triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] or pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].
• a method for producing a polyacetal copolymer according to one embodiment of the present invention is a method for copolymerizing trioxane with the above-mentioned comonomer in the presence of the above-mentioned polymerization catalyst (heteropolyacid (A) and heteropolyacid salt (B)).
• the polyacetal copolymer according to one embodiment of the present invention can be produced using known methods and polymerization apparatuses, such as batch or continuous methods.
• a commonly used reaction vessel equipped with an agitator can be used.
• a co-kneader, a twin-screw continuous extrusion mixer, a twin-screw paddle screw extruder, a vented twin-screw extruder, etc. can be used.
• the industrially preferred production method is the continuous method.
• the polyacetal copolymer according to one embodiment of the present invention can be obtained, for example, by continuously supplying a mixture containing trioxane, the above-mentioned comonomer, any additive for polymerization reaction, and a polymerization catalyst (heteropolyacid (A) and heteropolyacid salt (B)) to a continuous twin-shaft paddle screw extruder type polymerization reactor having a jacket for passing a heating or cooling medium, and polymerizing for a predetermined period of time.
• a polymerization catalyst heteropolyacid (A) and heteropolyacid salt (B)
• the desired polyacetal copolymer can be obtained by adding a basic compound such as an alkali metal compound, a quaternary amine compound, or a triazine compound having an amino group to the polyacetal copolymer obtained by the above-mentioned method, and then melt-kneading and subjecting the mixture to a catalyst deactivation treatment, etc.
• a basic compound such as an alkali metal compound, a quaternary amine compound, or a triazine compound having an amino group
• other components such as other polymers, other fillers, nitrogen compounds, stabilizers such as ultraviolet absorbers, acid inhibitors such as metal salts, antistatic agents, flame retardants, colorants such as dyes and pigments, lubricants, release agents, crystallization accelerators, and crystal nucleating agents may also be added as appropriate depending on the required performance.
• the other components may be used alone or in combination of two or more.
• the method for producing a polyacetal copolymer according to one embodiment of the present invention uses a mixture of heteropolyacid (A) and heteropolyacid salt (B) as a polymerization catalyst, which not only reduces the amount of formaldehyde generated but also enables the stable mass production of polyacetal copolymers that have excellent flowability during molding and can be used to produce molded products with excellent appearance.
• A heteropolyacid
• B heteropolyacid salt
• the polyacetal copolymer according to one embodiment of the present invention is a copolymer produced by the production method of the present invention. That is, the polyacetal copolymer is obtained by copolymerizing trioxane and the above-mentioned comonomer in the presence of a polymerization catalyst (heteropolyacid (A) and heteropolyacid salt (B)).
• a polymerization catalyst heteropolyacid (A) and heteropolyacid salt (B)
• the polyacetal copolymer obtained by the manufacturing method according to one embodiment of the present invention has excellent fluidity during molding. Furthermore, molded products produced from the polyacetal copolymer can reduce the amount of formaldehyde generated and have an excellent appearance.
• Polyacetal copolymer 1 Production of polyacetal copolymers 1 to 22 [Polyacetal copolymer 1] (Polymerization Apparatus)
• a continuous twin-shaft paddle screw extruder (hereinafter also referred to as "polymerization apparatus") was used as the polymerization apparatus.
• the extruder type is equipped with a jacket on the outside of the body for passing a heating or cooling medium.
• the body is divided into an upper and lower part, and the upper part can be opened.
• two rotating shafts with many paddles for stirring and propulsion are provided in the longitudinal direction.
• a mixed liquid containing 100 parts by mass of trioxane (TOX), 4.0 parts by mass of 1,3-dioxolane (DO), and a predetermined amount of methylal was continuously supplied per unit time to a polymerization apparatus in which a medium of 80° C. was passed through the jacket, and a mixture of 2.5 ppm of tungstophosphovanadic acid (A1) as the heteropolyacid (A) and 0.6 ppm of sodium tungstophosphoric acid salt (B1) as the heteropolyacid salt (B) was added as a methyl formate solution to carry out a polymerization reaction.
• TOX trioxane
• DO 1,3-dioxolane
• B1 sodium tungstophosphoric acid salt
• IRGANOX 1010 manufactured by BASF Japan, "IRGANOX” is a registered trademark of BASF
• melt flow rate (MFR) of the resulting copolymer would be 9 g/10 min.
• MFR melt flow rate
• 9 g refers to the range of "9 g ⁇ 0.3”.
• the above MFR was measured in accordance with ISO 1133 using a Melt Indexer L220 (manufactured by Tateyama Kagaku High-Technologies Co., Ltd.) under conditions of a load of 2.16 kg, a temperature of 190°C, and a resin discharge time of 7 minutes.
• Polyacetal copolymers 2 to 8 As shown in Table 1, pellets of polyacetal copolymers 2 to 8 were obtained by the same production method as for polyacetal copolymer 1, except that the amount of heteropolyacid (A) and/or heteropolyacid salt (B) added and the amount of methylal added were changed so that the MFR of the resulting copolymer would be 9 g/10 min.
• A heteropolyacid
• B heteropolyacid salt
• Polyacetal copolymer 9 As shown in Table 1, pellets of polyacetal copolymer 9 were obtained by the same production method as for polyacetal copolymer 1, except that the type of comonomer, the amount of heteropolyacid salt (B) added, and the amount of methylal added were changed so that the MFR of the resulting copolymer would be 9 g/10 min.
• Polyacetal copolymers 10 to 14 As shown in Table 1, pellets of polyacetal copolymers 10 to 14 were obtained by the same production method as for polyacetal copolymer 1, except that the type of heteropolyacid salt (B) and the amount of methylal added were changed so that the MFR of the resulting copolymer would be 9 g/10 min.
• Polyacetal copolymers 15-17, 19, 20 As shown in Table 1, pellets of polyacetal copolymers 15 to 17, 19, and 20 were obtained by the same production method as for polyacetal copolymer 1, except that the type of heteropolyacid salt (A), the amount of heteropolyacid salt (B) added, and the amount of methylal added were changed so that the MFR of the resulting copolymer would be 9 g/10 min.
• Polyacetal copolymer 18 As shown in Table 1, pellets of polyacetal copolymer 18 were obtained by the same production method as for polyacetal copolymer 1, except that the type of heteropolyacid salt (A), the type of heteropolyacid salt (B), and the amount of methylal added were changed so that the MFR of the resulting copolymer would be 9 g/10 min.
• Polyacetal copolymer 21 A mixed liquid containing 100 parts by mass of trioxane (TOX), 4.0 parts by mass of 1,3-dioxolane (DO), and a predetermined amount of methylal was continuously supplied to the above-mentioned polymerization apparatus per unit time, and 3.3 ppm of phosphotungstic acid (A5) was added as a heteropolyacid (A) in the form of a methyl formate solution to carry out a polymerization reaction.
• TOX trioxane
• DO 1,3-dioxolane
• A5 phosphotungstic acid
• Polyacetal copolymer 22 A mixed solution containing 100 parts by mass of trioxane (TOX), 4.0 parts by mass of 1,3-dioxolane (DO), and a predetermined amount of methylal was continuously fed to the above-mentioned polymerization apparatus per unit time, and 30 ppm of boron trifluoride (C) was added to carry out a polymerization reaction. Next, the crude polymer obtained from the discharge port of the polymerization apparatus was added to an aqueous solution containing 0.1% triethylamine to terminate the polymerization reaction, and the copolymer was then dried. The boron trifluoride (C) was added as a 0.3 wt % cyclohexane solution of a dibutyl ether complex.
• TOX trioxane
• DO 1,3-dioxolane
• C boron trifluoride
• heteropolyacid (A), heteropolyacid salt (B), and Lewis acid (C) described in the above-mentioned manufacturing method are the compounds shown in Table 1.
• the polyacetal copolymers 1 to 22 obtained by the above-mentioned production method were evaluated for the polymerization yield of the polyacetal copolymer, the appearance of a molded article using the polyacetal copolymer, the amount of formaldehyde generated, and bar flow (BF) evaluation.
• the mass of this formaldehyde was divided by the mass of the polyacetal copolymer used to obtain the amount of formaldehyde generated (unit: ppm). It is practically preferable that the amount of formaldehyde generated is 70 ppm or less.
• the size of the flow mark is less than 6 mm.
• 4 The size of the flow mark is 6 mm or more and less than 8 mm.
• 3 The size of the flow mark is 8 mm or more and less than 10 mm.
• 2 The size of the flow mark is 10 mm or more and less than 12 mm.
• 1 The size of the flow mark is 12 mm or more.
• the flow length at an injection pressure of 100 MPa is 450 mm or more.
• 4 The flow length at an injection pressure of 100 MPa is 440 mm or more and less than 450 mm.
• 3 The flow length at an injection pressure of 100 MPa is 430 mm or more and less than 440 mm.
• 2 The flow length at an injection pressure of 100 MPa is 420 mm or more and less than 430 mm.
• 1 The flow length at an injection pressure of 100 MPa is less than 420 mm.
• MFR which is an index of fluidity in melt state of the resulting crude polymer.
• the MFR was determined as follows. (Measuring method) Using a Melt Indexer L220 manufactured by Tateyama Kagaku High-Technologies Corporation, the measurement was performed under conditions conforming to ISO1133, such as a load of 2.16 kg, a temperature of 190° C., and a discharged resin acquisition time of 7 minutes.
• heteropolyacid (A), heteropolyacid salt (B), and Lewis acid (C) are as follows:
• the method of the present invention not only reduces the amount of formaldehyde generated, but also enables the stable mass production of polyacetal copolymers that have excellent flowability during molding and excellent appearance in molded products, and is expected to contribute to the advancement and dissemination of technology in this field.

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Citations (7)

• 2022
  • 2022-11-07 JP JP2022177930A patent/JP2024067677A/ja active Pending
• 2023
  • 2023-09-19 WO PCT/JP2023/033828 patent/WO2024100991A1/ja not_active Ceased
  • 2023-09-19 CN CN202380075985.1A patent/CN120225582A/zh active Pending

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