Method for producing polyacetal resin composition

Abstract

Provided is a method for producing a polyacetal resin composition that makes it possible to improve bonding strength in the vicinity of a weld.　A method for producing a polyacetal resin composition according to the present invention comprises: (i) adding a specific amount of a compound (c) that contains active hydrogen to a monomer mixture which contains trioxane (a) as a primary monomer, and then adding a specific polymerization catalyst (d) so as to perform polymerization, thereby obtaining a crude polyacetal resin; (ii) adding a specific basic compound (e) to the crude polyacetal resin and melt-kneading the resultant mixture, thereby deactivating the polymerization catalyst (d) to obtain a polyacetal resin (A); and (iii) blending 5-45 parts by mass of a thermoplastic polyurethane resin (B) and 0.5-2.5 parts by mass of an isocyanate compound (C) with 100 parts by mass of the polyacetal resin (A), thereby obtaining a polyacetal resin composition.

Description

Method for producing polyacetal resin composition

[0001] This disclosure relates to a method for producing a polyacetal resin composition.

[0002] Polyacetal resin (POM resin) possesses excellent properties in terms of mechanical properties, thermal properties, electrical properties, sliding properties, moldability, impact resistance, and dimensional stability of molded products, and is widely used as a structural material and mechanical component in electrical equipment, automotive parts, precision machine parts, and other applications.

[0003] Polyacetal resin compositions to which elastomers (e.g., thermoplastic polyurethane resin (TPU)) are added are known to improve the toughness of POM resin. However, because TPU has low compatibility with POM resin, it exists as fine particles in the resin composition. When such resin compositions are injection molded, there is a problem that the joint strength near the weld of molded products obtained from polyacetal resin compositions containing TPU is lower than the joint strength of resin compositions that do not contain TPU.

[0004] Patent Document 1 proposes a molding material comprising POM and a thermoplastic elastomer, which has improved impact strength.

[0005] Japanese Patent Publication No. 2015-078388

[0006] Even with the molding material described in Patent Document 1, the improvement in bonding strength near the weld is insufficient.

[0007] The object of this disclosure is to provide a method for producing a polyacetal resin composition that can improve the bonding strength near the weld.

[0008] This disclosure includes the following aspects: [1] A method for producing a polyacetal resin composition, the method comprising: (i) adding 50 to 500 ppm by mass of a compound (c) containing active hydrogen to a monomer mixture comprising 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond, and then the following general formula (I): H ｍ [M １ ｘ ・M ２ｙ O Ｚ ・nH ２ O ・・・(I) (In formula (I), M １ represents P, Si, B or Ge, and M ２ represents one or more elements selected from W, Mo and V, x represents a number of 1 or more and 10 or less, y represents a number of 6 or more and 40 or less, z represents a number of 10 or more and 100 or less, m represents a number of 1 or more, and n represents a number of 0 or more and 50 or less.) which is a heteropolyacid represented by the above, or a mixture of said heteropolyacid and a salt of said heteropolyacid, polymerizing by adding a polymerization catalyst (d) to obtain a crude polyacetal resin; (ii) adding to said crude polyacetal resin, as a basic compound (e), one or more selected from carbonates, hydrogen carbonates, carboxylates and hydrates thereof of an alkali metal or a Group 2 element (excluding Be), and / or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g / L aqueous solution, then melt-kneading to deactivate said polymerization catalyst (d) to obtain a polyacetal resin (A); (iii) blending, based on 100 parts by mass of said polyacetal resin (A), 5 parts by mass or more and 45 parts by mass or less of a thermoplastic polyurethane resin (B), and 0.5 parts by mass or more and 2.5 parts by mass or less of an isocyanate compound (C) to obtain a polyacetal resin composition. A manufacturing method comprising the above steps.

[0009] According to the present disclosure, it is possible to provide a method for producing a polyacetal resin composition capable of improving the bonding strength near a weld.

[0010] One embodiment of the present disclosure will be described in detail below, but the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each embodiment disclosed herein can be combined with any other features disclosed herein. If multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range. The lower and / or upper limits of the numerical ranges described herein may be replaced with numerical values ​​within that range, as shown in the examples. The expression "X to Y" indicating a numerical range means "X or greater and Y or less". If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments.

[0011] [Method for Producing Polyacetal Resin Composition] This disclosure relates to a method for producing a polyacetal resin composition. The production method according to this embodiment involves adding 50 to 500 ppm by mass of a compound (c) containing active hydrogen to a monomer mixture containing (i) 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond, and then the following general formula (I): H ｍ [M １ ｘ ・M ２ ｙ O Ｚ ]・nH ２ O ... (I) (In formula (I), M １ represents P, Si, B, or Ge, and M ２x represents one or more elements selected from W, Mo, and V; x represents a number between 1 and 10; y represents a number between 6 and 40; z represents a number between 10 and 100; m represents a number greater than or equal to 1; and n represents a number between 0 and 50. (ii) Adding a polymerization catalyst (d), which is a heteropoly acid represented by ) or a mixture of the heteropoly acid and a salt of the heteropoly acid, to perform polymerization to obtain a crude polyacetal resin; (ii) Adding one or more basic compounds (e) selected from alkali metals or group 2 elements (except Be), carbonates, bicarbonates, carboxylates and hydrates thereof, and / or nitrogen-containing organic compounds with a pH of 10 g / L aqueous solution of 10 or higher, to the crude polyacetal resin and melt-kneading to deactivate the polymerization catalyst (d) to obtain a polyacetal resin (A); (iii) Blending 5 to 45 parts by mass of thermoplastic polyurethane resin (B) and 0.5 to 2.5 parts by mass of isocyanate compound (C) with 100 parts by mass of the polyacetal resin (A) to obtain a polyacetal resin composition.

[0012] According to the manufacturing method of this embodiment, a polyacetal resin composition can be obtained that can improve the bonding strength near the weld. In this disclosure, "bonding strength near the weld" can be evaluated by a test piece including a weld formed by the collision of the leading edges of the flowing resin. In particular, if the bonding strength of the weld is insufficient, the tensile elongation (TE) of the test piece tends to decrease. The resin composition obtained by the manufacturing method of this embodiment may also include a polyacetal resin composition in which the tensile elongation of the test piece including the weld is high.

[0013] <Step (i)> In the manufacturing method according to this embodiment, step (i) involves adding 50 to 500 ppm by mass of a compound (c) containing active hydrogen to a monomer mixture containing 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond, and then adding the following general formula (I): H ｍ [M １ ｘ ・M ２ｙ O Ｚ ]・nH ２ O ... (I) (In formula (I), M １ represents P, Si, B, or Ge, and M ２ The process involves adding a polymerization catalyst (d), which is a heteropoly acid represented by (x) (where x represents one or more elements selected from W, Mo, and V; x represents a number between 1 and 10; y represents a number between 6 and 40; z represents a number between 10 and 100; m represents a number of 1 or more; and n represents a number between 0 and 50;) or a mixture of the heteropoly acid and a salt of the heteropoly acid, and carrying out polymerization to obtain a crude polyacetal resin.

[0014] (Monomer mixture) The monomer mixture comprises 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond.

[0015] (Trioxane (a)) The main monomer, trioxane (a), is a cyclic trimer of formaldehyde and is generally obtained by reacting an aqueous solution of formaldehyde in the presence of an acidic catalyst. This is then purified by methods such as distillation before use. It is preferable that the trioxane used in polymerization has had impurities such as water and methanol reduced as much as possible.

[0016] The proportion of trioxane (a) in the monomer mixture is 80 to 99.9 mol%, preferably 90 to 99.8 mol%, relative to the total amount of all monomers contained in the monomer mixture (100 mol%). By setting the proportion of trioxane (a) to 80 to 99.9 mol%, the polyacetal resin (A) (hereinafter sometimes referred to as "resin (A)") has sufficient mechanical properties and its melting point does not decrease easily.

[0017] (Comonomer (b)) The monomer mixture contains one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond. Examples of comonomers (b) include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, and epichlorohydrin. These may be used individually or in combination of two or more. Of these, from the viewpoint of polymerization stability, one or more selected from the group consisting of 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide are preferred.

[0018] The proportion of comonomer (b) in the monomer mixture is preferably 0.1 to 20 mol%, and more preferably 0.2 to 10 mol%, relative to the total amount of all monomers contained in the monomer mixture (100 mol%). If the proportion of comonomer (b) is within the above range, it is easier to suppress the increase in unstable end portions in the polyacetal resin (A) and the deterioration of its stability, and the melting point of the resin (A) is less likely to decrease.

[0019] The monomer mixture may contain other monomers (second comonomer components) besides trioxane (a) and comonomer (b). Known modifying agent comonomers, such as branching agents, can be used as the second comonomer component. In one preferred embodiment, the monomer mixture contains only trioxane (a) and comonomer (b).

[0020] (Compound (c) containing active hydrogen) Step (i) comprises adding 50 to 500 mass ppm of compound (c) containing active hydrogen (hereinafter sometimes referred to as "compound (c)") to the above-mentioned monomer mixture. By adding 50 to 500 mass ppm of compound (c) to the monomer mixture, the compatibility between the finally obtained polyacetal resin (A) and the thermoplastic polyurethane resin (B) is improved. It is presumed that the reason for this is that the compatibility between the polyacetal resin and the thermoplastic polyurethane resin is improved. The "compound containing active hydrogen" refers to a compound having a group or structure capable of generating active hydrogen. Compound (c) preferably contains one or more selected from water and lower alcohols. Examples of lower alcohols include methanol, ethanol and the like. In a preferred embodiment, from the viewpoint of the addition amount, it is preferable that compound (c) contains water.

[0021] From the viewpoint of improving weld strength, the addition amount of compound (c) to the monomer mixture is preferably 50 to 300 mass ppm, and more preferably 100 to 200 mass ppm.

[0022] (Polymerization catalyst (d)) The polymerization catalyst (d) is represented by the following general formula (I): H ｍ [M １ ｘ ・M ２ ｙ O Ｚ ・nH ２ O ...(I) (In formula (I), M １ represents P, Si, B or Ge, M ２ represents one or more elements selected from W, Mo and V, x represents a number from 1 to 10, y represents a number from 6 to 40, z represents a number from 10 to 100, m represents a number of 1 or more, and n represents a number from 0 to 50.) It is a heteropolyacid represented by the formula, or a mixture of the heteropolyacid and a salt of the heteropolyacid. In addition, y represents the number of M ２ , but when M ２ contains two or more elements, it represents the total number of these two or more elements. Also, H in formula (I) represents hydrogen.

[0023] The polymerization catalyst (d) may contain one type of the heteropolyacid represented by formula (I) alone, or may be a mixture of two or more types of heteropolyacids. Alternatively, it may be a mixture of the heteropolyacid represented by formula (I) and a salt of said heteropolyacid. The heteropolyacid contained in the mixture and the heteropolyacid in the salt of the heteropolyacid may be the same or different. Further, the mixture may contain two or more types of heteropolyacids and two or more types of heteropolyacid salts. Examples of heteropolyacid salts include lithium salts, sodium salts, potassium salts, and the like.

[0024] Many conventional methods for producing polyacetal resins require a large amount of polymerization catalyst. Therefore, in order to deactivate the polymerization catalyst, a step of immersing the crude polyacetal resin in a solution containing a deactivator for a long time (immersion step) is required. The inventors of the present application considered that this immersion step might affect the compatibility between the finally obtained polyacetal resin and the thermoplastic polyurethane resin. That is, it was considered that a polyacetal resin that has undergone a long-time immersion step tends to have poorer compatibility with thermoplastic polyurethane resin, which in turn tends to further reduce the bonding strength near the weld. The production method according to the present embodiment reduces the amount of catalyst added by using a specific polymerization catalyst (d), thereby enabling the omission of the immersion step for deactivating the catalyst. Furthermore, after adding a certain amount of the above compound (c) to the monomer mixture, polymerizing the monomers using the polymerization catalyst (d) further improves the compatibility between the resulting polyacetal resin (A) and the thermoplastic polyurethane resin (B) described below, whereby a polyacetal resin composition capable of improving the bonding strength near the weld can be obtained.

[0025] The heteropolyacid contained in polymerization catalyst (d) is preferably one or more selected from phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicic acid, silicic acid, silicic acid, and silicic acid, phosphomolybdotungstovanadic acid. The salt of the heteropolyacid is preferably one or more selected from lithium phosphotungstate, sodium phosphotungstate, potassium phosphotungstate, sodium silicic acid, sodium phosphomolybdate, and sodium phosphotungstovanadate. In terms of superior catalytic activity, it is more preferable to include one or more heteropolyacids selected from phosphotungstic acid and phosphomolybdic acid, or a mixture of the one or more heteropolyacids and one or more salts of the heteropolyacids. The salt of the heteropolyacid is more preferably one or more selected from sodium phosphotungstate and sodium phosphomolybdate. In a preferred embodiment, the polymerization catalyst (d) is phosphotungstic acid or phosphomolybdic acid, or a mixture of phosphotungstic acid and sodium phosphotungstate.

[0026] In one embodiment, when a mixture of a heteropoly acid and a salt of the heteropoly acid is used as the polymerization catalyst (d), the ratio of heteropoly acid to heteropoly acid salt (mass ratio) is preferably 1:15 to 1:30.

[0027] When adding polymerization catalyst (d) as a solution, polymerization catalyst (d) may be dissolved in a solvent. Preferred solvents include, but are not limited to, esters obtained by the condensation of low molecular weight carboxylic acids having 1 to 10 carbon atoms, such as formic acid, acetic acid, propionic acid, and butyric acid, and low molecular weight alcohols having 1 to 10 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 3-methyl-1-butanol, and 1-hexanol; and low molecular weight ketones having 1 to 10 carbon atoms, such as acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, and methyl-t-butyl ketone. Considering industrial availability and other factors, methyl formate, ethyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, 2-butanone, methyl isobutyl ketone, etc. are preferred. In one embodiment, the concentration of polymerization catalyst (d) in the solution may be 0.1 to 30% by mass, or 0.1 to 10% by mass.

[0028] In the manufacturing method according to this embodiment, polyacetal resin (A) can be obtained in high yield even with a small amount of polymerization catalyst (d) added. In one embodiment, the amount of polymerization catalyst (d) added to the monomer mixture may be 1.0 to 20.0 ppm by mass, or 1.5 to 10.0 ppm by mass. The polymerization catalyst (d) minimizes undesirable reactions such as main chain decomposition and depolymerization of the polymer by the polymerization catalyst (d), and prevents unstable formate end groups (-O-CH=O) and hemiacetal end groups (-O-CH=O). ２ Because it easily suppresses the formation of -OH and other compounds, a polyacetal resin (A) with good physical properties can be easily obtained even with a small amount of additive.

[0029] In step (i), compound (c) is added at a concentration of 50 to 500 ppm by mass to a monomer mixture containing trioxane (a) and comonomer (b). Then, the monomer mixture containing compound (c) and polymerization catalyst (d) are placed in a polymerization reactor to carry out the polymerization reaction. Step (i) is preferably carried out by bulk polymerization using trioxane (a) as the melt, and it is generally preferable to start the polymerization at a temperature of 65°C to 114°C. After polymerization, the crude polyacetal resin precipitates because it is insoluble in trioxane (a). To prevent it from forming rock-like chunks, it is preferable to pulverize the crude polyacetal resin by stirring it at high speed. In one embodiment, from the viewpoint of sustaining the reaction and suppressing depolymerization, the polymerization temperature is preferably 65°C to 130°C, and more preferably 70°C to 125°C.

[0030] The time required to carry out step (i) (polymerization time) is not particularly limited, as it depends on the concentration of the polymerization catalyst (d), the concentration of the comonomer (b), and / or the reaction temperature, but it is generally preferable to carry it out for 0.5 to 10 minutes.

[0031] In one embodiment, step (i) may include adding a molecular weight modifier to the monomer mixture. Examples of molecular weight modifiers include methylal, ethylal, dibutoxymethane, bis(methoxymethyl) ether, bis(ethoxymethyl) ether, and bis(butoxymethyl) ether. Among these, it is preferable to use one or more linear formal compounds selected from methylal, ethylal, and dibutoxymethane.

[0032] In one embodiment, step (i) may involve adding an antioxidant to the monomer mixture.

[0033] <Step (ii)> Step (ii) is to add one or more basic compounds (e) selected from carbonates, bicarbonates, carboxylates and hydrates thereof of alkali metals or group 2 elements (except Be), and / or a nitrogen-containing organic compound with a pH of 10 or higher in a 10 g / L aqueous solution, to the crude polyacetal resin and melt-knead the mixture to deactivate the polymerization catalyst (d) and obtain polyacetal resin (A).

[0034] In step (ii), the basic compound (e) functions as a deactivator for the polymerization catalyst (d). In the manufacturing method according to this embodiment, it is not necessary to immerse the crude polyacetal resin in a solution containing the deactivator for a long time, as in the conventional method. That is, the polymerization catalyst (d) can be deactivated by melt-kneading the basic compound (e).

[0035] Basic compound (e) is one or more compounds selected from alkali metals or group 2 elements (excluding Be), specifically carbonates, bicarbonates, carboxylates, and hydrates thereof, and / or nitrogen-containing organic compounds with a pH of 10 g / L aqueous solution of 10 or higher. That is, basic compound (e) is one or more compounds selected from alkali metal carbonates, alkali metal bicarbonates, alkali metal carboxylates, hydrates of these alkali metal salts, alkaline earth metal (excluding Be) carbonates, group 2 elements (excluding Be) bicarbonates, group 2 elements (excluding Be) carboxylates, hydrates of these group 2 elements (excluding Be) salts, and nitrogen-containing organic compounds with a pH of 10 g / L aqueous solution of 10 or higher. Note that the pH of nitrogen-containing organic compounds with a pH of 10 g / L aqueous solution of 10 or higher is the pH at 25°C.

[0036] In one embodiment, Na or K is preferred as the alkali metal salt. Furthermore, Mg and Ca are preferred as the other group 2 elements besides Be.

[0037] Preferred examples of alkali metal carbonates or carbonates of Group II elements (excluding Be) include sodium carbonate, potassium carbonate, calcium carbonate, and magnesium carbonate. Preferred examples of alkali metal bicarbonates or bicarbonates of Group II elements (excluding Be) include sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, and magnesium bicarbonate. Preferred examples of alkali metal carboxylates or carboxylates of Group II elements (excluding Be) include sodium formate, sodium acetate, potassium acetate, and higher fatty acid salts (e.g., disodium succinate, sodium laurate, sodium palmitate, sodium stearate, calcium stearate, etc.). Furthermore, examples of nitrogen-containing organic compounds with a pH of 10 g / L aqueous solution of 10 or higher include amine compounds such as triethylamine, choline hydroxide, trimethylamine, and ethanolamine.

[0038] Of these, it is preferable that one or more are selected from alkali metals or group 2 elements (except Be) as carbonates, bicarbonates, carboxylates, and hydrates of these salts, more preferably including carboxylates of alkali metals or group 2 elements (except Be), and even more preferably including higher fatty acid salts of alkali metals or group 2 elements (except Be). In one embodiment, the basic compound (e) may include stearate of an alkali metal or group 2 element (except Be) (preferably one or more selected from sodium stearate and potassium stearate).

[0039] The basic compound (e) may be added as a solid (powder) or as a solution.

[0040] When adding a basic compound (e) as a solution, it is preferable to use a solvent containing active hydrogen. Examples of solvents containing active hydrogen include water, C1-C5 alcohols, and formic acid. Examples of C1-C5 alcohols include methanol, ethanol, n-propanol, isopropanol, and n-butanol. Of these, water is preferred from the viewpoint of solubility.

[0041] In one embodiment, the amount of basic compound (e) added is preferably 5 to 200 ppm by mass, and more preferably 5 to 100 ppm by mass, relative to the crude polyacetal resin.

[0042] Step (ii) deactivates the polymerization catalyst (d) in the container resin, thus eliminating the immersion and drying steps in conventional manufacturing methods. Furthermore, since unreacted monomers can be easily recovered, monomer loss is reduced.

[0043] In step (ii), the basic compound (e) may be introduced from the main feed section of the extruder or from the side feed section of the extruder. Step (ii) may also include adding the basic compound (e) to the crude polyacetal resin obtained in step (i), melt-kneading it to deactivate the polymerization catalyst (d) to obtain polyacetal resin (A), and then cooling the resin (A) discharged from the extruder outlet and cutting it with a strand cutter to obtain pellet-shaped resin (A).

[0044] (Polyacetal resin (A)) The polyacetal resin (A) obtained in step (ii) contains oxymethylene groups (-CH ２ The resin is a polymer compound whose main constituent unit is 1,3-(O-), and is a polyoxymethylene homopolymer in which only oxymethylene groups are constituent units, or a copolymer, terpolymer, or block polymer in which oxymethylene groups are the main constituent units and other constituent units, such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, etc., are contained in small amounts.

[0045] The polyacetal resin (A) obtained by the manufacturing method according to this embodiment has superior compatibility with the thermoplastic polyurethane resin (B) described later, and therefore the bonding strength near the weld can be improved.

[0046] In one embodiment, the melt index (MI) of the polyacetal resin (A), measured according to ISO 1133 (at 190°C and a 2.16 kg load), is preferably 1 to 100 g / 10 min, more preferably 1 to 50 g / 10 min, and even more preferably 2 to 50 g / 10 min.

[0047] <Step (iii)> Step (iii) is to obtain a polyacetal resin composition by blending 5 to 45 parts by mass of thermoplastic polyurethane resin (B) and 0.5 to 2.5 parts by mass of isocyanate compound (C) with 100 parts by mass of polyacetal resin (A).

[0048] (Thermoplastic polyurethane resin (B)) In this embodiment, the thermoplastic polyurethane resin (B) (hereinafter sometimes referred to as "resin (B)") to be compounded with resin (A) is not particularly limited. In one embodiment, it may be a reaction product of the following components (b1) to (b3): ​​(b1) component: diisocyanate compound, (b2) component: high molecular weight polyol with an average molecular weight (Mw) of 500 to 5000, (b3) component: low molecular weight polyol and / or polyamine with an average molecular weight (Mw) of 60 to 500.

[0049] (Component (b1)) Examples of component (b1) include 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate, cyclopentylene-1,3-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexylene-1,4-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of isomers of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, and 4,4'-methylene Examples include bis(phenylisocyanate), 2,2-diphenylpropane-4,4'-diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, xylenediisocyanate, 1,4-naphthalenediisocyanate, 1,5-naphthalenediisocyanate, 4,4'-diphenyldiisocyanate, azobenzene-4,4'-diisocyanate, m- or p-tetramethylxylenediisocyanate, 1-chlorobenzene-2,4-diisocyanate, etc. These may be used individually or in combination of two or more. Of these, preferred are 4,4'-methylenebis(phenylisocyanate), 1,6-hexamethylenediisocyanate, 2,4-tolylenediisocyanate, isophorone diisocyanate, etc.

[0050] (Component (b2)) Component (b2) is a high molecular weight polyol with Mw of 500 to 5000, preferably 1000 to 3000. Component (b2) can form the soft segments of resin (B). Such high molecular weight polyols mainly include polyester diols (including polycarbonate ester diols) and polyether diols having hydroxyl groups at both ends, and a portion of them may be triols, etc.

[0051] Examples of polyester diols include those obtained by the reaction of one or more dihydric alcohols with one or more dicarboxylic acids. Suitable dicarboxylic acids that constitute these include adipic acid, succinic acid, sebacic acid, suberic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, thiodipropionic acid, citraconic acid, and mixtures containing small amounts of aromatic dicarboxylic acids. Other suitable dihydric alcohols that can be used as components include 1,3- or 1,2-propylene glycol, 1,4-butanediol, 1,3-butanediol, 2-methylpentanediol, 1,5-diethylene glycol, 1,5-pentanediol, 1,6-pentanediol, 1,12-dodecanediol, and mixtures thereof.

[0052] Furthermore, oxycarboxylic acids, lactones, and carbonates, such as ε-caprolactone and 3-oxylbutyric acid, can also be used as components of polyester diols.

[0053] In one embodiment, the polyester diol is preferably one or more selected from polyadipic acid ester diols, polylactone diols, and polycarbonate ester diols.

[0054] The polyetherdiol is preferably a condensation product of one or more alkylene glycols, such as ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, and 1,5-pentanediol, and mixtures thereof. Polyalkylene ether glycol can also be produced from tetrahydrofuran. Furthermore, the polyetherdiol may be a polyether glycol derived from ethylene oxide, propylene oxide, and / or tetrahydrofuran (THF) as a comonomer, particularly a disordered comonomer or block comonomer, and a THF polyether copolymer, which is a copolymer of THF and a small amount of 3-methylTHF, can also be used.

[0055] In one embodiment, the polyetherdiol is preferably one or more selected from poly(tetramethylene ether) glycol (PTMEG), poly(propylene oxide) glycol, copolymer of propylene oxide and ethylene oxide, and copolymer of tetrahydrofuran and ethylene oxide, and more preferably contains poly(tetramethylene ether) glycol.

[0056] In one embodiment, the polyetherdiol may be polybutazineol.

[0057] (Component (b3)) Component (b3) is a low molecular weight polyol and / or polyamine with Mw of 60 to 500. These are mainly one or more selected from aliphatic linear diols or diamines, or aromatic diols or diamines, and may contain a small amount of triol. Component (b3) becomes a rigid segment of resin (B) and can also play a role in chain extension and crosslinking.

[0058] Examples of low molecular weight polyols include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, ethylene glycol, propylene glycol, glycerin, hexanetriol, trimethylolpropane, hydroquinone dietilol ether, resorcinol ethylol ether, etc. Examples of polyamines include diphenylmethanediamine, m-phenylenediamine, or derivatives thereof. In one embodiment, component (b3) is preferably one or more selected from ethylene glycol, propylene glycol, 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, hydroquinone dietilol ether, resorcinol ethylol ether, and derivatives thereof.

[0059] In one embodiment, the resin (B) is preferably a polyurethane resin in which component (b3) is present in an amount of 0.2 to 5 equivalents per equivalent of component (b2).

[0060] In step (iii), the proportion of resin (B) to be blended with resin (A) is 5 parts by mass or more and 45 parts by mass or less. In one embodiment, the proportion of resin (B) may be 10 to 45 parts by mass or 5 to 10 parts by mass.

[0061] (Isocyanate compound (C)) In this embodiment, a diisocyanate compound is preferred as the isocyanate compound (C) (hereinafter sometimes referred to as "compound (C)") to be blended into the resin (A). In one preferred embodiment, a derivative of the diisocyanate compound is included, and in one more preferred embodiment, a trimer of the isocyanate compound is included.

[0062] Examples of compound (C) include 4,4'-methylenebis(phenylisocyanate), 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, xylylenediisocyanate, 1,6-hexamethylenediisocyanate, isophoronediisocyanate, 1,5-naphthalenediisocyanate, or derivatives thereof (derivatives of diisocyanate compounds). Examples of diisocyanate compound derivatives include dimers or trimers of the above-mentioned diisocyanate compounds. Of these, one or more selected from 4,4'-methylenebis(phenylisocyanate), isophorone diisocyanate, 1,5-naphthalene diisocyanate, l,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and derivatives thereof of these diisocyanate compounds is preferred, more preferably derivatives thereof are included, even more preferably trimers thereof are included, and particularly preferably trimers of isophorone diisocyanate are included.

[0063] In step (iii), the proportion of compound (C) to be blended into resin (A) is 0.5 parts by mass or more and 2.5 parts by mass or less. In one embodiment, the proportion of compound (C) may be 0.6 to 2.5 parts by mass, 0.5 to 1 part by mass, or 1 to 1.5 parts by mass.

[0064] (Other Components) Step (iii) may include blending other components other than the resin (B) and compound (C) into the resin (A). Other components may include various known stabilizers and additives. Examples of stabilizers include hindered phenol compounds, nitrogen-containing basic compounds (excluding basic compound (e)), alkali metal or alkaline earth metal hydroxides, etc. These may be used individually or in combination of two or more. Examples of additives include general additives for thermoplastic resins, such as dyes, pigments and other colorants, lubricants, nucleating agents, mold release agents, antistatic agents, and surfactants, one or more of these.

[0065] <Polyacetal Resin Composition> The polyacetal resin composition according to this embodiment is prepared by the method for producing the polyacetal resin composition described above. The polyacetal resin composition contains 5 to 45 parts by mass of thermoplastic polyurethane resin (B) and 0.5 to 2.5 parts by mass of isocyanate compound (C) per 100 parts by mass of polyacetal resin (A). In addition to resins (A), (B), and compound (C), the polyacetal resin composition may also contain other components as described above.

[0066] In one embodiment, the proportion of resin (A) in the polyacetal resin composition is preferably 60 to 95% by mass, more preferably 65 to 94% by mass, and even more preferably 80 to 94% by mass, based on the total mass of the resin composition. The proportion of resin (B) is preferably 2 to 35% by mass, more preferably 5 to 30% by mass, and even more preferably 5 to 10% by mass. The proportion of compound (C) is preferably 0.1 to 2% by mass, more preferably 0.3 to 1.8% by mass, and even more preferably 0.5 to 1.5% by mass.

[0067] The polyacetal resin composition according to this embodiment can improve the bonding strength near the weld. In one embodiment, the elongation of the weld portion of a molded article made of the polyacetal resin composition, measured in accordance with ASTM D 256, may be 9% or more, or 10% or more.

[0068] [Applications] The polyacetal resin composition according to this embodiment can provide molded articles with improved bonding strength near the weld. Such molded articles can be suitably used for applications such as clips and trims.

[0069] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] A method for producing a polyacetal resin composition, the method comprising: (i) adding 50 to 500 ppm by mass of a compound (c) containing active hydrogen to a monomer mixture comprising 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond, and then the following general formula (I): H ｍ [M １ ｘ ・M ２ ｙ O Ｚ ]・nH ２ O ... (I) (In formula (I), M １ represents P, Si, B, or Ge, and M ２x represents one or more elements selected from W, Mo, and V; x represents a number between 1 and 10; y represents a number between 6 and 40; z represents a number between 10 and 100; m represents a number greater than or equal to 1; and n represents a number between 0 and 50. A method for producing a polyacetal resin, comprising: (ii) adding a polymerization catalyst (d), which is a heteropoly acid represented by ) or a mixture of the heteropoly acid and a salt of the heteropoly acid, to carry out polymerization to obtain a crude polyacetal resin; (ii) adding one or more basic compounds (e) selected from carbonates, bicarbonates, carboxylates and hydrates thereof of alkali metals or group 2 elements (except Be), and / or a nitrogen-containing organic compound with a pH of 10 or higher in a 10 g / L aqueous solution, to the crude polyacetal resin and melt-kneading to deactivate the polymerization catalyst (d) to obtain a polyacetal resin (A); (iii) blending 5 to 45 parts by mass of thermoplastic polyurethane resin (B) and 0.5 to 2.5 parts by mass of isocyanate compound (C) with 100 parts by mass of the polyacetal resin (A) to obtain a polyacetal resin composition. [2] The method for producing an isocyanate compound (C) comprising a derivative of a diisocyanate compound, according to [1]. [3] The method for producing an isocyanate compound (C) comprising a trimer of an isocyanate compound, according to [1] or [2]. [4] The method for producing an active hydrogen-containing compound (c) comprising one or more selected from water and lower alcohols, according to any one of [1] to [3]. [5] The method for producing an active hydrogen-containing compound (c) comprising water, according to any one of [1] to [4]. [6] The method for producing an active hydrogen-containing compound (c) comprising one or more heteropoly acids selected from phosphotungstic acid and phosphomolybdic acid, or a mixture of one or more heteropoly acids and one or more salts of heteropoly acids, according to any one of [1] to [5]. [7] The method for producing an active hydrogen-containing compound (e) comprising a carboxylate of an alkali metal or a group 2 element (excluding Be), according to any one of [1] to [6]. [8] The method for producing the basic compound (e) according to any one of [1] to [7], wherein the basic compound (e) comprises a higher fatty acid salt of the alkali metal or a group 2 element (excluding Be).Each configuration and its combination in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments.

[0070] The present disclosure will be further illustrated by the following examples, but these examples will not limit the interpretation of the present disclosure.

[0071] [Example 1] Water at 80°C was passed through the water jacket of a continuous twin-screw polymerizer, which was equipped with a jacket on the outside for passing a heating or cooling medium through, and had two rotating shafts attached to numerous paddles for stirring, propulsion, and pulverization running longitudinally inside. The polymerizer's rotating shafts were rotated at a predetermined speed, and trioxane (a) and comonomer (b) (1,3-dioxolane) were added and mixed in the proportions shown in Table 1 to obtain a monomer mixture. Then, 100 ppm by mass of compound (c1) (water) containing active hydrogen as shown in Table 1 was added to the monomer mixture. Next, 5 ppm by mass of polymerization catalyst (d1) (phosphotungstic acid) was added to carry out bulk polymerization. The polymerization catalyst (d1) was introduced into the polymerizer as a methyl formate solution. After polymerization, the obtained crude polyacetal resin was pulverized to obtain powdered crude polyacetal resin. Next, 75 ppm by mass of basic compound (e1) (sodium stearate) and 0.3% by mass of antioxidant (hinder-to-phenol antioxidant, manufactured by BASF Japan Ltd., product name "Irganox® 1010") were added to the powdered crude polyacetal resin, and the mixture was melt-kneaded in a twin-screw extruder to deactivate the polymerization catalyst (d) and obtain polyacetal resin (A4). The polyacetal resin composition of Example 1 was obtained by mixing 100 parts by mass of the obtained polyacetal resin (A4), 10 parts by mass of thermoplastic polyurethane resin (B1) (manufactured by BASF Japan Ltd., product name "Elastran® S80A10"), and 1 part by mass of isocyanate compound (C1) (trimer of isophorone diisocyanate, manufactured by Evonik Corporation, product name "Vestanat T1890 / 100").

[0072] The obtained polyacetal resin composition was injection molded to produce ISO TYPE 1A test specimens. The tensile strength (TS) and tensile elongation (TE) of the obtained test specimens were measured in accordance with ISO 527-1,2. The Charpy impact strength (notched, 23°C) was also measured in accordance with ISO 179-1eA. Furthermore, a dumbbell-shaped test specimen with a thickness of 2 mm and a weld in the center was prepared by injection molding in a mold with gates at both ends, under conditions of mold temperature of 80°C and cylinder temperature of 200°C. The elongation (TE) (2 mmt weld) (%) of the weld portion of the obtained test specimen was measured in accordance with ASTM D 256. The results are shown in Table 1.

[0073] [Examples 2-16, Comparative Examples 4-5] Polyacetal resins (A1)-(A3) and (A5)-(A11) were prepared under the same conditions as in Example 1, except that the compounds (c), polymerization catalyst (d), and basic compound (e) shown in Table 1 were blended in the proportions shown in Table 1. In Comparative Example 4, polyacetal resin (A1) was prepared without adding compound (c). Furthermore, polyacetal resin compositions were prepared under the same conditions as in Example 1, except that each polyacetal resin (A), thermoplastic polyurethane resin (B), and isocyanate compound (C) were blended in the proportions shown in Tables 2-3. The obtained polyacetal resin compositions were injection molded under the same conditions as in Example 1, and the tensile strength (TS), tensile elongation (TE), Charpy impact strength, and weld elongation (TE) (2mmt weld) were measured. The results are shown in Table 2.

[0074] [Comparative Examples 1-2, 6-8] Polyacetal resin compositions were prepared under the same conditions as in Example 1, except that a polyacetal resin (A4) prepared under the conditions shown in Table 1 was blended with a thermoplastic polyurethane resin (B) and / or an isocyanate compound (C) in the proportions shown in Table 3. The obtained polyacetal resin compositions were injection molded under the same conditions as in Example 1, and the tensile strength (TS), tensile elongation (TE), Charpy impact strength, and weld elongation (TE) (2mmt weld) were measured. The results are shown in Table 3.

[0075] [Comparative Example 3] Under the same conditions as in Example 1, the rotating shaft of the polymerizer was rotated at a predetermined speed, and trioxane (a) and comonomer (b) (1,3-dioxolane) were added and mixed in the proportions shown in Table 1 to obtain a monomer mixture. Then, 100 ppm by mass of compound (c1) (water) containing active hydrogen, as shown in Table 1, was added to the monomer mixture. Next, the polymerization catalyst (d'1) (boron trifluoride) was added in the form of a dibutyl ether complex so that the amount of boron trifluoride was 40 ppm by mass, and bulk polymerization was carried out. The polymerization catalyst (d'1) was introduced into the polymerizer as a dibutyl ether solution. After polymerization, the obtained crude polyacetal resin was pulverized to obtain powdered crude polyacetal resin. Next, the powdered crude polyacetal resin was immersed in an aqueous solution containing 1% basic compound (e4) (triethylamine) to deactivate the polymerization catalyst (d'1), and then recovered and dried. The dried material was mixed with 0.3% by mass of an antioxidant (hindered phenol-based antioxidant, manufactured by BASF Japan Ltd., product name "Irganox 1010") and melt-kneaded in a twin-screw extruder to obtain polyacetal resin (A12). 100 parts by mass of the obtained polyacetal resin (A12), 10 parts by mass of thermoplastic polyurethane resin (B1), and 1 part by mass of isocyanate compound (C1) were mixed to obtain the polyacetal resin composition of Comparative Example 3. The obtained polyacetal resin composition was injection molded under the same conditions as in Example 1, and the tensile strength (TS), tensile elongation (TE), Charpy impact strength, and weld elongation (TE) (2mmt weld) were measured. The results are shown in Table 3.

[0076]

[0077] The materials used for each of the materials listed in Table 1 and for the preparation of the polyacetal resin compositions are as follows: • Comonomer (b): 1,3-Dioxolane, • Compound (c1): Water, • Compound (c2): Methanol, • Polymerization catalyst (d1): Phosphateungstic acid, • Polymerization catalyst (d2): Phosphatemolybdic acid, • Polymerization catalyst (d3): Mixture of phosphotungstic acid and sodium phosphotungstate, • Polymerization catalyst (d'1): Boron trifluoride, • Basic compound (e1): Sodium stearate, • Basic compound (e2): Sodium carbonate, • Basic compound (e3): Potassium stearate, • Basic compound (e4): Triethylamine, • Antioxidant: Hindertophenol antioxidant, manufactured by BASF Japan Ltd., product name "Irganox 1010"), • Thermoplastic polyurethane resin (B1): manufactured by BASF Japan Ltd., product name "Elastran S80A10", - Thermoplastic polyurethane resin (B2): Manufactured by Nippon Miractran Co., Ltd., product name "Miractran (registered trademark) E180MNAT", - Isocyanate compound (C1): Trimer of isophorone diisocyanate (Manufactured by Evonik Corporation, product name "Vestanat T1890 / 100"), - Isocyanate compound (C2): Diphenylmethane 4,4'-diisocyanate (MDI) (Manufactured by Tosoh Corporation, product name "Monomeric MDI (Millionate MT)"), - Isocyanate compound (C3): Dimer of toluene diisocyanate (TDI).

[0078]

[0079]

[0080] As shown in Tables 1 to 3, the resin compositions of Examples 1 to 16 obtained by the manufacturing method according to this embodiment exhibited sufficiently high elongation at the weld zone. On the other hand, the resin compositions of Comparative Examples 1, 3, 4, and 6 exhibited inferior elongation at the weld zone compared to those of the examples. Comparative Examples 2 and 5 demonstrate that the problem of elongation at the weld zone does not occur when TPU is not included. Comparative Examples 7 and 8 exhibited elongation at the weld zone similar to that of the examples, but were undesirable due to insufficient or excessive isocyanate compound (C). From these results, it was confirmed that the manufacturing method according to this embodiment can yield polyacetal resin compositions that can improve bonding strength near the weld zone.

[0081] According to the manufacturing method of this embodiment, a polyacetal resin composition can be obtained that can improve the bonding strength near the weld. Therefore, it can be suitably used for clips, trims, and the like, and has industrial applicability.

Claims

1. A method for producing a polyacetal resin composition, wherein the production method comprises: (i) adding 50 to 500 mass ppm of a compound (c) containing active hydrogen to a monomer mixture containing 80 to 99.9 mol% of trioxane (a) and one or more comonomers (b) selected from cyclic ethers and cyclic formals having at least one carbon-carbon bond, then polymerizing by adding a polymerization catalyst (d), which is a heteropolyacid represented by the following general formula (I) or a mixture of the heteropolyacid and a salt of the heteropolyacid, to obtain a crude polyacetal resin: H ｍ [M １ ｘ ·M ２ ｙ O Ｚ ·nH ２ O ... (I) (In formula (I), M １ represents P, Si, B or Ge, M ２ represents one or more elements selected from W, Mo and V, x represents a number from 1 to 10, y represents a number from 6 to 40, z represents a number from 10 to 100, m represents a number of 1 or more, and n represents a number from 0 to 50.) ; (ii) adding, to the crude polyacetal resin, as a basic compound (e), one or more selected from carbonates, hydrogen carbonates, carboxylates of alkali metals or Group 2 elements (excluding Be) and hydrates thereof, and / or a nitrogen-containing organic compound having a 10 g / L aqueous solution with a pH of 10 or higher, followed by melt-kneading to deactivate the polymerization catalyst (d) and obtain a polyacetal resin (A); (iii) blending, based on 100 parts by mass of the polyacetal resin (A), 5 to 45 parts by mass of a thermoplastic polyurethane resin (B) and 0.5 to 2.5 parts by mass of an isocyanate compound (C) to obtain a polyacetal resin composition. The production method described above.

2. The manufacturing method according to claim 1, wherein the isocyanate compound (C) includes a derivative of a diisocyanate compound.

3. The method for producing the isocyanate compound (C) according to claim 1 or 2, wherein the isocyanate compound (C) comprises a trimer of the isocyanate compound.

4. The manufacturing method according to claim 1 or 2, wherein the compound (c) containing the active hydrogen comprises one or more selected from water and lower alcohols.

5. The manufacturing method according to claim 1 or 2, wherein the compound (c) containing the active hydrogen contains water.

6. The production method according to claim 1 or 2, wherein the polymerization catalyst (d) comprises one or more heteropoly acids selected from phosphotungstic acid and phosphomolybdic acid, or comprises a mixture of the one or more heteropoly acids and a salt of the one or more heteropoly acids.

7. The manufacturing method according to claim 1 or 2, wherein the basic compound (e) comprises a carboxylate of the alkali metal or group 2 element (excluding Be).

8. The manufacturing method according to claim 1 or 2, wherein the basic compound (e) comprises a higher fatty acid salt of the alkali metal or group 2 element (excluding Be).

Images