CN1244209A - Polyacetal resin composition - Google Patents

Polyacetal resin composition Download PDF

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CN1244209A
CN1244209A CN 95197924 CN95197924A CN1244209A CN 1244209 A CN1244209 A CN 1244209A CN 95197924 CN95197924 CN 95197924 CN 95197924 A CN95197924 A CN 95197924A CN 1244209 A CN1244209 A CN 1244209A
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metal
carboxylic acid
polyacetal resin
aliphatic carboxylic
metal salt
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CN1109072C (en
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冈美喜夫
畑忠重
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Asahi Kasei Corp
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Asahi Kasei Kogyo KK
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Abstract

A polyacetal resin composition comprising an end-stabilized polyacetal resin and at least one metal salt of an aliphatic carboxylic acid, wherein the metal salt contains at least either a metal hydroxide or a metal chloride occulded therein and further contains at least either a metal hydroxide or a metal chloride deposited on the surface thereof in such a manner that the amounts of the occuladed metal compounds and the deposited metal compounds are respectively 1-300 and 0-20 ppm by weight based on the total amount of the metal salt, the occluded compounds and the deposited compounds. The composition is excellent in the resistances to thermal aging and aging discoloration and the prevention of mold deposit.

Description

Polyacetal resin composition
Technical Field
The present invention relates to a polyacetal resin composition. More specifically, the present invention relates to a polyacetal resin composition comprising a polyacetal resin stabilized at its terminal and at least 1 metal salt of an aliphatic carboxylic acid, wherein the metal salt of an aliphatic carboxylic acid contains a specific amount of at least 1 metal compound selected from the group consisting of a metal hydroxide and a metal chloride in an occluded state; further, the metal salt of aliphatic carboxylic acid has no or extremely limited specific amount of at least one metal compound selected from the group consisting of metal hydroxide and metal chloride in a state of being attached to the surface thereof. The polyacetal resin composition of the present invention is excellent not only in heat aging resistance but also in resistance to aged discoloration and prevention of mold adhesion, and can be suitably used for various applications, particularly for the production of mechanical parts used for a long period of time under high temperature conditions (for example, parts around automobile engines).
Prior Art
Polyacetal resins are extremely excellent in terms of mechanical strength, chemical resistance and slidability in combination and are easy to process, and therefore, they are widely used as typical engineering plastics, mainly as parts of electrical and electronic equipment, automobile parts and other devices.
When polyacetal resins are used in these fields, heat aging resistance and age discoloration resistance are indispensable characteristics, and prevention of mold adhesion is also an important characteristic from the viewpoint of molding productivity.
Conventionally, as a method for improving the heat aging resistance of polyacetal resin, a metal salt of an aliphatic carboxylic acid has been generally added [ for example, Japanese patent publication No. 55-22508 (corresponding to U.S. Pat. No. 3,743,614) and Japanese patent publication No. 60-56748 (corresponding to GB laid-open No. 1425771)].
However, when a conventionally known metal salt of aliphatic carboxylic acid is added to a polyacetal resin, the heat aging resistance is improved to some extent, but the aging discoloration resistance and the mold adhesion resistance are deteriorated. The deterioration of the resistance to aged discoloration results in poor appearance of the molded article, while the prevention of the deterioration of the mold adhesion results in high frequency of disassembling and cleaning of the mold, which leads to a problem in molding productivity. It is therefore highly desirable to solve the problems of these prior art techniques.
Summary of The Invention
The present inventors have made intensive studies to solve the above problems, and as a result, have unexpectedly found a polyacetal resin composition obtained by adding a specific metal salt of aliphatic carboxylic acid, which is a metal salt of aliphatic carboxylic acid having a metal compound selected from metal hydroxides and metal chlorides in a occluded state and, as the case may be, a metal compound selected from metal hydroxides and metal chlorides in a state of being attached to the surface thereof, to a polyacetal resin having stabilized at the terminals; the amount of the occluded metal compound and the amount of the metal compound attached to the surface thereof are 1 to 300 ppm by weight and 0 to 20ppm by weight, respectively, relative to the total weight of the metal salt ofaliphatic carboxylic acid, the occluded metal compound and the metal compound attached to the surface thereof; the polyacetal resin composition thus obtained was excellent not only in heat aging resistance but also in aging discoloration resistance and mold adhesion prevention. The present invention has been completed based on this finding.
Accordingly, a main object of the present invention is to provide a polyacetal resin composition which is not obtained by the prior art, and which satisfies all of the characteristics of heat aging resistance, heat aging discoloration resistance and mold adhesion prevention at the same time.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description of the invention and from the claims. Detailed description of the invention
The polyacetal resin composition according to the present invention is a polyacetal resin composition comprising 100 parts by weight of a terminal-stabilized polyacetal resin and 0.01 to 3.0 parts by weight of at least 1 metal salt of an aliphatic carboxylic acid;
characterized in that the metal salt of aliphatic carboxylic acid has at least 1 metal compound selected from the group consisting of metal hydroxides and metal chlorides in a occluded state, and the metal salt of aliphatic carboxylic acid has at least 1 metal compound selected from the group consisting of metal hydroxides and metal chlorides in a state of being attached to the surface thereof, and the amount of the occluded metal compound and the amount of the metal compound attached to the surface thereof are 1 to 300 ppm by weight and 0 to 20ppm by weight, respectively, relative to the total weight of the metal salt of aliphatic carboxylic acid, the occluded metal compound and the metal compound attached to the surface thereof.
The polyacetal resin composition of the present invention has excellent heat aging resistance and age discoloration resistance, and solves the problems of poor physical properties (due to insufficient heat aging resistance) and poor appearance (due to insufficient age discoloration resistance) which have been problems when a molded article composed of a conventional polyacetal resin composition is used under a high-temperature atmosphere. Further, the polyacetal resin composition of the present invention is excellent in mold adhesion prevention and can improve molding productivity. The polyacetal resin composition of the present invention can be suitably used for molding various machine parts, particularly machine parts around automobile engines.
JP-B55-22508 and JP-B60-56748 disclose methods of adding a metal salt of an aliphatic carboxylic acid to improve the heat aging resistance of a polyacetal resin, but the above-mentioned two publications do not describe the content of the metal hydroxide or the metal chloride in the metal salt of an aliphatic carboxylic acid used at all, and do not describe the production method of the metal salt of an aliphatic carboxylic acid.
Examples of the terminal-stabilized polyacetal resin in the resin composition of the present invention include a resin composition obtained by terminal-stabilizing a oxymethylene homopolymer which is obtained from an oxymethylene monomer or a cyclic oligomer such as a trimer (trioxane) or a tetramer (tetraoxane) thereof as a raw material and which is substantially composed of oxymethylene units, and a resin composition obtained by terminal-stabilizing a oxymethylene-oxyalkylene copolymer which is obtained from the above raw material and a cyclic formal such as ethylene oxide, propylene oxide, epichlorohydrin, 1, 3-dioxolane, 1, 4-butanediol, formal of ethylene glycol or formal of diethylene glycol to which a hindered phenol-based antioxidant is added in an amount of 10 to 500ppm and which contains 0.1 to 20% by weight of an oxyalkylene unit having 2 to 8 carbon atoms. The amount of formaldehyde gas generated when the polyacetal resin having stabilized terminal in the present invention is heated at 230 ℃ for 60 minutes under a nitrogen stream is preferably 600 ppm by weight or less, more preferably 300 ppm by weight or less, based on the weight of the polyacetal resin. The terminal-stabilized polyacetal resin in the present invention may be an oxymethylene-oxyalkylene copolymer composed of molecular chains having a branched structure, or an oxymethylene block copolymer composed of 50% by weight or more of a Polyoxymethylene (POM) block and 50% by weight or less of a polymer block different from the POM, which contains 50% by weight or more of an oxymethylene repeating unit. Examples of the shape of the oxymethylene block copolymer include A-B-A and A-B (A represents a polyoxymethylene block, B represents a hetero polymer block containing 50% by weight or more of an oxymethylene repeating unit), and the amount of the B block is 50% by weight or less of the total block copolymer.
Preferred examples of the hindered phenol-based antioxidant which can be added to a comonomer such as ethylene oxide, propylene oxide, epichlorohydrin, 1, 3-dioxolane, 1, 4-butanediol and the like include: n-octadecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) -propionate, n-octadecyl-3- (3 ' -methyl-5 ' -tert-butyl-4 ' -hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) -propionate, 1, 6-hexanediol-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionate, 1, 4-butanediol-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propane]Acid esters], tetrakis [ methylene-3- (3 ', 5' -di-tert-butyl-4 '-hydroxyphenyl) propionate]methane, 3, 9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy } -1, 1-dimethylethyl]2, 4, 8, 10-tetraoxaspiro (5, 5) decaalkane, N' -bis-3- (3 ', 5' -di-tert-butyl-4-hydroxyphenyl) propionylhexamethylenediamine, N '-tetramethylenebis-3- (3' -methyl-5 '-tert-butyl-4-hydroxyphenyl) propionyldiamine, N' -bis- [3- (3, 5-di-tert-butyl-4-hydroxyphenol) propionyl]hydrazine, N-salicyloyl-N '-salicylidene hydrazine, 3- (N-salicyloyl) amino-1, 2, 4-triazole, N' -bis [2- {3- (3, 5-di-butyl-4-hydroxyphenyl) propionyloxy } ethyl]hydroxyamide, and the like. These antioxidants may be used in combination of 1 kind or 2 or more kinds. Among them, tetrakis [ methylene-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate]methane is preferable.
The method for producing the terminal-stabilized polyacetal resin used in the present invention is not particularly limited, and the terminal-stabilized polyacetal resin can be produced by a conventionally known method. For example, in the case of copolymerization, trioxane and a cyclic ether as a comonomer are copolymerized by removing impurity compounds having active hydrogen such as water, methanol and formic acid contained in the raw material monomers by distillation, adsorption or the like, and the resulting polymer is treated with a twin-screw extruder or the like to stabilize the terminal. Examples of the method for removing the active hydrogen compound in the raw material monomer include a method in which trioxane and a cyclic ether are distilled in the presence of benzene, respectively, and the benzene and the active hydrogen compound are azeotropically removed; in addition, as the adsorption method, a method of removing trioxane and cyclic ether by passing them through a column filled with an adsorbent such as zeolite can be cited. In the production of the terminal-stabilized polyacetal resin of the present invention, impurities in the raw material, for example, active hydrogen compounds such as water, methanol and formic acid, are removed by distillation or adsorption, and the concentration of the total amount ofthe active hydrogen (OH hydrogen) containing compounds in the raw material monomer is preferably regulated to 20ppm or less in terms of water relative to trioxane. The polyacetal resin before the terminal stabilization can be obtained by copolymerizing the starting materials from which the inactive hydrogen compound is removed by any method such as distillation or adsorption in the presence of a catalyst. The polymerization method may be carried out by bulk polymerization, or by any of batch-wise and continuous methods. As the batch polymerization apparatus, a reaction vessel with a stirrer which is generally used can be used. As the continuous type, a kneading extruder, a self-cleaning type mixer such as a twin-screw type continuous extrusion kneader, a twin-screw paddle type continuous mixer or the like can be used. The polymerization conditions are carried out at atmospheric pressure at a temperature in the range of from 60 ℃ to 200 ℃, preferably from 60 ℃ to 120 ℃.
As the polymerization catalyst, boron trifluoride hydrate, and a complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are generally used. Can be in gaseous form or suitableA solution of an organic solvent is used. The preferred polymerization catalyst is a complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride. Specific examples thereof include boron trifluoride diethyl ether and boron difluoride dibutyl ether. The amount of the polymerization catalyst to be added is preferably 1X 10 to 1 mole of the total amount of trioxane and cyclic ether-6mole-1X 10-3Molar, preferably 5X 10-6mole-1X 10-4And (3) mol.
The polyacetal resin before the terminal stabilization to be obtained contains an active polymerization catalyst, and therefore, it is desired to deactivate the polymerization catalyst. The method of deactivating the polymerization catalyst may be carried out by deactivating the polymerization catalyst in an aqueous solution containing an alkaline substance or in an organic solvent. As another method of deactivation, a method of adding a basic substance to the polyacetal resin before the terminal stabilization and deactivating the resin in a molten state by an extruder may be used. Examples of the basic substance used in the deactivation reaction include hydroxides of alkali metals or alkaline earth metals, salts of inorganic weak acids, and salts of organic acids. Preferred are hydroxides, carbonates, phosphates, silicates, borates, formates, acetates, stearates, palmitates, propionates, oxalates, and the like of lithium, sodium, potassium, magnesium, calcium, strontium, and barium. Ammonia, and amine compounds such as triethylamine and tributylamine may also be used as the deactivator.
The method of stabilizing the polymer ends after the deactivation of the polymerization catalyst includes, for example, a method of stabilizing the ends by removing volatile components from a molten polyacetal resin by means of a twin-screw extruder which can continuously carry out an operation for stabilizing the ends comprising at least 2 stages of steps such as (1) a step of injecting at least 1 kind of hydroxyl group-containing compound (for example, an alkali metal or alkaline earth metal hydroxide) into the molten polymer and then kneading the mixture, and (2) a degassing step of releasing steam and free formaldehyde of the injected hydroxyl group-containing compound. It is preferable to inject the at least 1 hydroxyl group-containing compound or a mixture thereof and then add a basic substance such as triethylamine as a pH adjuster during kneading. The amount of the basic substance added is 0001 to 10 wt%, preferably 0.02 to 1.0 wt%, based on the polyacetal resin before the terminal stabilization. In the case of hydroxides, salts of inorganic weak acids and salts of organic acids of alkali metals or alkaline earth metals, the concentration is 2 to 5000ppm, preferably 10 to 2000 ppm. When water and/or an organic solvent is added together with the basic substance, the amount of water and/or the organic solvent is 0.01 to 10 wt% based on the polyacetal resin before the terminal stabilization. The terminal stabilization temperature is within a temperature range of-265 ℃ which is the melting point of the polyacetal resin. Particularly preferred temperatures are from 180 ℃ to 230 ℃. As for details of the method for stabilizing the terminal of a polyacetal resin, for example, Japanese patent application laid-open No. Sho 58-11450 (corresponding to USP4366305), Japanese patent application laid-open No. Sho 58-152012 (corresponding to EP 0088541) and International application No. PCT/JP95/00530 can be cited.
It is also possible to add a hindered phenol-based antioxidant during the polymerization of the polyacetal or before the unstable terminal treatment. Examples of the hindered phenol-based antioxidant which may be added at this time include n-octadecyl-3- (3 ', 5 ' -di-t-butyl-4 ' -hydroxyphenyl) -propionate, n-octadecyl-3- (3 ' -methyl-5 ' -t-butyl-4 ' -hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5 ' -di-t-butyl-4 ' -hydroxyphenyl) -propionate, 1, 6-hexanediol-bis- [3- (3, 5-di-t-butyl-4-hydroxyphenyl) -propionate], 1, 4-butanediol-bis- [3- (3, 5-di-t-butyl-4-hydroxyphenyl) -propionate], (meth) acrylic acid, and mixtures thereof, Triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], pentaerythrityl-tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate], 3, 9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy } -1, 1-dimethylethyl]2, 4, 8, 10-tetraoxaspiro (5, 5) undecane, N '-bis-3- (3', 5 '-di-tert-butyl-4-hydroxyphenyl) propionylhexamethylenediamine, N' -tetramethylenebis-3- (3 '-methyl-5' -tert-butyl-4-hydroxyphenyl) propane An acid diamine, N ' -bis [3- (3, 5-di-tert-butyl-4-hydroxyphenol) propionyl]hydrazine, N-salicyloyl-N ' -salicylidene hydrazine, 3- (N-salicyloyl) amino-1, 2, 4-triazole, N ' -bis [2- {3- (3, 5-di-butyl-4-hydroxyphenyl) propionyloxy } ethyl]hydroxyamide, and the like. These antioxidants may be used in combination of 1 or more than 2. Among them, triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate]is preferable.
The amount of formaldehyde gas generated from the terminal-stabilized polyacetal resin can be measured by the following method. The terminal-stabilized polyacetal resin was charged into an aluminum container, heated and melted at 230 ℃ for 60 minutes under a nitrogen stream, and the formaldehyde gas generated at this time was absorbed into an aqueous sodium sulfite solution, and the amount of formaldehyde gas generated was determined from the amount titrated with 0.01 equivalent of sulfuric acid. The amount of formaldehyde gas generated from the polyacetal resin is preferably 600 ppm by weight or less, more preferably 300 ppm by weight or less, based on the weight of the terminal-stabilized polyacetal resin.
The metal salt of an aliphatic carboxylic acid as used herein means a metal salt of a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms. In the present invention, 1 or 2 or more of these metal salts of aliphatic carboxylic acid can be used. These carboxylic acids may also be substituted with hydroxyl groups. Examples of the saturated aliphatic carboxylic acid include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, and cerotic acid. Examples of the unsaturated aliphatic carboxylic acid include undecylenic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassidic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, and stearynoic acid. Among these aliphatic carboxylic acids,lauric acid, stearic acid and behenic acid are particularly preferable. The metal of the metal salt of aliphatic carboxylic acid is selected from sodium, potassium, lithium, calcium, magnesium, barium, zinc, aluminum, strontium. Among these metals, calcium, magnesium, barium, zinc, strontium are preferable; calcium, magnesium, zinc are particularly preferred.
The amount of the metal salt of aliphatic carboxylic acid added is 0.01 to 3.0 parts by weight, preferably 0.01 to 1.0 part by weight, more preferably 0.01 to 0.5 part by weight, based on 100 parts by weight of the polyacetal resin. When the amount of the metal salt of aliphatic carboxylic acid added is less than 0.01 part by weight, the heat aging resistance is poor; if the amount exceeds 3.0 parts by weight, discoloration after aging becomes severe, resulting in a problem of poor appearance of the molded article and also in prevention of reduction in mold adhesion.
The method for producing the desired metal salt of aliphatic carboxylic acid used in the present invention is not particularly limited as long as it can obtain a metal salt of aliphatic carboxylic acid having at least 1 metal compound selected from metal hydroxide and metal chloride in a occluded state and having at least 1 metal compound selected from metal hydroxide and metal chloride in a state of being attached to the surface thereof, the amount of the occluded metal compound and the amount of the metal compound attached to the surface thereof being 1 to 300 ppm by weight and 0 to 20ppm by weight, respectively, based on the total weight of the metal salt of aliphatic carboxylic acid, the occluded metal compound and the metal compound attached to the surface thereof. For example, a granular crude product of a metal salt of aliphatic carboxylic acid is prepared by a neutralization reaction between an aliphatic carboxylic acid represented by the following formula (I) and a metal hydroxide, a metathesis reaction between a metal salt of aliphatic carboxylic acid represented by the following formula (II) and a metal chloride, or a neutralization reaction between an aliphatic carboxylic acid represented by the following formula (III) and a metal oxide, and the obtained crude product of a metal salt of aliphatic carboxylic acid is repeatedly washed with water under stirring and dehydrated until the metal hydroxide attached to the surface of the metal salt of aliphatic carboxylic acid becomes 20ppm by weight or less and the occluded metal hydroxide becomes 1 to 300 ppm by weight, whereby a metal salt of aliphatic carboxylic acid desired in the present invention can be obtained.
As described above, the crude product of an aliphatic carboxylic acid salt for obtaining a specific aliphatic carboxylic acid metal salt used in the present invention by the water washing treatment can be prepared, for example, by a neutralization reaction represented by the following formula (I), a metathesis reaction represented by the following formula (II), a neutralization reaction represented by the following formula (III), or the like.
(I)
(wherein R represents an alkyl group, an alkenyl group or an alkynyl group, M represents a metal atom having a valence of 1 or more, and x is an integer determined by the valence of M and is 1 or more.)
(II) (wherein R represents an alkyl group, an alkenyl group or an alkynyl group, M represents a 1-valent metal atom, and M' represents a 2-valent metal atom.)
(III) (wherein R represents an alkyl group, an alkenyl group or an alkynyl group, and M' represents a 2-valent metal atom.)
In the reaction of the formula (I), a crude product of the metal salt of an aliphatic carboxylic acid can be obtained by the reaction of an aliphatic carboxylic acid with a metal hydroxide. When a crude salt product of a metal aliphatic carboxylate is produced by the reaction of the formula (I), an excess amount of M (OH) is added to prevent unreacted RCOOH (aliphatic carboxylic acid) from remainingx(Metal hydroxide), thus unreacted M (OH)xRemains so as to be occluded in RCOOM (crude product of metal salt of aliphatic carboxylic acid obtained), and also adheres to the surface.
In the reaction of the above formula (II), the reaction is carried out by using a metal salt of aliphatic carboxylic acid (RCOOM) as a raw material and a metal chloride (M' Cl) as a reactant2) The reaction of (A) to obtain a crude metal salt of aliphatic carboxylic acid [ (RCOO)2M’]. In the production of a crude product of a metal salt of aliphatic carboxylic acid by the reaction of the above formula (II), M' Cl is excessively added so that unreacted ROOM (metal salt of aliphatic carboxylic acid as a raw material) does not remain2(metal chloride), thus unreacted M' Cl2Remains so as to be occluded in (RCOO)2M' (crude product of the metal salt of aliphatic carboxylic acid obtained) and also adhered to the surface. In addition, when the formula (II) is reacted,since MCl is formed as a by-product, M' Cl is removed2Besides, MCl is also adsorbed and also adheres to the surface. For example, the metal salt of aliphatic carboxylic acid (RCOOM) as the raw material is sodium aliphatic carboxylate, and the metal chloride (M' Cl) as the reactant2) In the case of calcium chloride, the crude metal salt of aliphatic carboxylic acid produced is calcium aliphatic carboxylate, and sodium chloride is produced as a by-product, and this sodium chloride is adsorbed together with unreacted calcium chloride and also adheres to the surface.
In the reaction of the above formula (III), a crude metal salt of an aliphatic carboxylic acid can be obtained by the reaction of an aliphatic carboxylic acid with a metal oxide. Production of crude fatty acid metal salt by the reaction of the above formula (III)In the case of production, M' O (metal oxide) is added in an excess amount so that unreacted RCOOH (aliphatic carboxylic acid) does not remain. M "O which does not react with RCOOH generally reacts with water in the reaction system to form hydroxide [ M" (OH)x]The hydroxide is occluded in (RCOO)2M "(crude product of metal salt of aliphatic carboxylic acid obtained) is also attached to the surface, and a part of M' O tends to remain as it is.
Furthermore, in the reaction of the formula (I), M (OH)xWhen M (metal) of the (metal hydroxide) is n-valent, M (OH)xThe amount of (b) is 1.01 to 1.1 mol, preferably 1.01 to 1.05 mol, based on n mol of RCOOH (aliphatic carboxylic acid).
In the reaction of the formula (II), M' Cl2The amount of the (metal chloride) to be added is 1.01 to 1.1 mol, preferably 1.01 to 1.05 mol, based on 2 mol of RCOOM (metal salt of aliphatic carboxylic acid).
In the reaction of the formula (III), M' O (metal oxide) is added in an amount of 1.01 to 1.1 mol, preferably 1.01 to 1.05 mol, relative to 2 mol of ROOH (aliphatic carboxylic acid).
As shown in the above (I), an aliphatic carboxylic acid (RCOOH) and a metal hydroxide [ M (OH)]x]In the case of producing a crude metal salt of aliphatic carboxylic acid (RCOOM) to be subjected to a water washing treatment, the metal [ i.e., metal hydroxide [ M (OH)]of the crude metal salt of aliphatic carboxylic acid (RCOOM) to be subjected to a water washing treatmentx]Metal (M)]Is a metal having a valence of 1 or more. In the present invention, examples of the metal having a valence of 1 or more in the formula (I) include sodium, potassium, lithium, calcium, magnesium, barium, zinc, lead and strontium.
As shown in the above formula (II), a metal salt of aliphatic carboxylic acid (RCOOM) as a raw material and a metal chloride (M' Cl) as a reactant are used2) The reaction of (2) to prepare a crude metal salt of aliphatic carboxylic acid [ (RCOO) to be subjected to a water washing treatment2M’]In this case, the metal (M) of the metal salt of aliphatic carboxylic acid (RCOOM) [ i.e., metal chloride (MCl) as a by-product]is used as the raw materialMetal (M)]Is a metal salt of a 1-valent metal, and is subjected to a water washing treatment (RCOO)2M’]Metal (M') [ i.e. metal chloride as reactantSubstance (M' Cl)2) Metal (M')]Is a 2-valent metal. In the present invention, examples of the 1-valent metal (M) in the formula (II) include sodium, potassium, and lithium. Examples of the 2-valent metal (M') in the formula (II) include calcium, magnesium, barium, zinc and strontium.
As shown in the above formula (III), a crude metal salt of aliphatic carboxylic acid [ (RCOO) to be subjected to a water washing treatment is prepared by the reaction of an aliphatic carboxylic acid (RCOOH) as a raw material and a metal oxide (M' O) as a reactant2M”]Then, the crude metal salt of aliphatic carboxylic acid [ (RCOO) is subjected to washing treatment with water2M”]Metal (M ') [ i.e., metal (M ') of metal oxide (M ' O) as a reactant]]Is a 2-valent metal. In the present invention, examples of the 2-valent metal (M ") in the formula (III) include calcium, magnesium, barium, zinc, and strontium.
In the production of a crude metal salt of aliphatic carboxylic acid (RCOOM) to be subjected to water washing treatment by the reaction of the formula (I), an aliphatic carboxylic acid (RCOOH) is first added to water at a temperature of from above the melting point of the aliphatic carboxylic acid to-95 ℃ with stirring, the resulting emulsion is cooled to below the melting point of the aliphatic carboxylic acid, and a metal hydroxide [ M (OH)x]After mixing the aqueous solution or aqueous suspension, heating the mixed solution to a temperature higher than the melting point of the aliphatic carboxylic acid by-95 ℃, standing for 1-3 hours for reaction, filtering the reaction mixed solution, and dehydrating to obtain the aliphatic carboxylic acid.
In the production of a crude metal salt of aliphatic carboxylic acid (RCOOM ') to be subjected to water washing treatment by the reaction of the formula (II), a metal salt of aliphatic carboxylic acid (RCOOM) as a raw material is dissolved in water at 50 to 95 ℃ and the resulting aqueous solution is mixed with a metal chloride (M' Cl)2) Mixing the above aqueous solutions, standing at 50-95 deg.C for 1-3 hr for reaction, filtering the reaction mixture, and dehydrating.
Using the reaction of formula (III), a crude metal salt of aliphatic carboxylic acid [ (RCOO) to be subjected to a water washing treatment is prepared2M”]In the case of (I), the reaction is carried out in the same manner as in the case of (I), namely, first, an aliphatic carboxylic acid (RCOOH) is added to water at a temperature of from above the melting point of the aliphatic carboxylic acid to 95 ℃ inclusive, the resulting emulsion is stirred, cooled to below the melting point of the aliphatic carboxylic acid, and then suspended in an aqueous solution or suspension of a metal oxide (M' O)Mixing the floating liquids, heating the mixed solution to a temperature higher than the melting point of the aliphatic carboxylic acid by-95 ℃, standing for 1-3 hours for reaction, filtering the reaction mixed solution, and dehydrating to obtain the aliphatic carboxylic acid.
The crude fatty acid metal salt obtained by the reaction of the above formula (I) may be used as a raw material for the reaction of the above formula (II).
Further, the method of obtaining the crude product of the metal salt of aliphatic carboxylic acid to be subjected to the water washing treatment is not limited to the method utilizing the above-mentioned reactions of the formulae (I), (II), (III).
The crude product of the metal salt of aliphatic carboxylic acid thus obtained is repeatedly washed with water under stirring and dehydrated until the surface metal compound becomes 20ppm by weight or less and the occluded metal compound becomes 1 to 300 ppm by weight, whereby the metal salt of aliphatic carboxylic acid desired in the present invention is obtained.
In the present invention, the metal of the desired metal salt of aliphatic carboxylic acid, which is obtained by washing the crude metal salt of aliphatic carboxylic acid obtained by the reaction of the above formula (I), formula (II) or formula (III), is preferably selected from among 2-valent metals, such as calcium, magnesium, barium, zinc and strontium.
The metal of the metal compound selected from the group consisting of metal hydroxide and metal chloride to be occluded in the desired metal salt of aliphatic carboxylic acid is preferably selected from sodium, potassium, lithium, calcium, magnesium, barium, zinc and strontium.
In the present invention, when the metal compound to be occluded in the desired metal salt of aliphatic carboxylic acid subjected to the water washing treatment is composed of a plurality of kinds of metal compounds, the amount of the occluded metal compound means the total amount of the plurality of kinds of metal compounds to be occluded. Also, in the present invention, when the metal compound adhering to the surface of the desired metal salt of aliphatic carboxylic acid to be subjected to the water washing treatment is composed of a plurality of kinds of metal compounds, the amount of the metal compound adhering to the surface means the total amount of the plurality of kinds of metal compounds adhering to the surface.
The metal compound contained in the desired metal salt of aliphatic carboxylic acid to be subjected to the water washing treatment and the metal compound attached to the surface in the present invention can be quantified by the method using an ion chromatograph shown below.
2 samples of the desired metal salt of aliphatic carboxylic acid to be subjected to water washing treatment were prepared in equal weight, the 1 st sample was put into pure water in an amount of 5 times (V/W) the amount of the sample or more, the sample was subjected to ultrasonic treatment at room temperature for 1 hour, the metal salt of aliphatic carboxylic acid was filtered, and the metal ion and counter ion in the filtrate were quantified by an ion chromatograph, whereby the amount of the metal compound (W) attached to the surface of the metal salt of aliphatic carboxylic acid was determined1). On the other hand, the 2 nd sample of the desired metal salt of aliphatic carboxylic acid to be subjected to the water washing treatment was put into methanol in an amount 5 times (V/W) as large as or more than that of the sample, subjected to ultrasonic treatment at a temperature of 60 ℃ for 1 hour, and the metal salt of aliphatic carboxylic acid was filtered. Mixing the filtrate with pure water at a volume ratio of 1: 1, and determining the metal ion and counter ion in the obtained mixture by ion chromatography to obtain the 2 nd sample of the metal salt of aliphatic carboxylic acidTotal amount of metal compounds (W) present on the surface and in the interior2). The amount of the metal compound to be included in the metal salt of aliphatic carboxylic acid may be selected from (W)2) Is subtracted from the value of (W)1) The value of (3).
The counter ion is at least 1 selected from hydroxyl ion and chloride ion, but the hydroxyl ion cannot be directly quantified by ion chromatography. However, the metal ion and the chloride ion can be directly quantified, and thus, the hydroxyl ion can also be quantified according to the quantitative value of the metal ion, or the quantitative values of the metal ion and the chloride ion.
As described above, the metal salt of aliphatic carboxylic acid used in the present invention contains at least 1 metal compound selected from the group consisting of metal hydroxide and metal chloride in a occluded state, and does not contain or contains a very limited amount of at least 1 metal compound selected from the group consisting of metal hydroxide and metal chloride in a state of being attached to the surface thereof, and the amount of the occluded metal compound and the amount of the metal compound attached to the surface are 1 to 300 ppm by weight and 0 to 20ppm by weight, respectively, relative to the total weight of the metal salt of aliphatic carboxylic acid, the amount of the occluded metal compound and the total weight of the metal compounds attached to the surface thereof.
The polyacetal resin composition of the present invention, which is obtained by adding 0.01 to 3.0 parts by weight of the metal salt of an aliphatic carboxylic acid to 100 parts by weight of the terminal-stabilized polyacetal resin, is excellent in all of heat aging resistance, age discoloration resistance and mold adhesion prevention. The amount of the metal compound to be occluded is in the range of 1 to 300 ppm by weight, preferably 1 to 50ppm by weight, more preferably 1 to 10ppm by weight, relative to the total weight of the metal salt of aliphatic carboxylic acid, the occluded metal compound and the metal compound attached to the surface. When the amount of the occluded metal compound exceeds 300 ppm by weight, the polyacetal resin composition is remarkably deteriorated in age-related discoloration resistance, resulting in a problem of poor appearance of the molded article. Furthermore, deterioration of the mold adhesion is prevented. On the other hand, when the amount of the occluded metal compound is less than 1ppm by weight, the heat aging resistance is lowered. The amount of the metal compound attached to the surface is 20ppm by weight or less, preferably 10ppm by weight or less, and more preferably 0ppm by weight, based on the total weight of the metal salt of aliphatic carboxylic acid, the occluded metal compound, and the metal compound attached to the surface. If it exceeds 20ppm by weight, the decrease in the mold adhesion is prevented.
In the present invention, various known additives commonly used for polyacetal resins can be used without particular limitation as required. Examples thereof include an antioxidant, a formaldehyde-reactive nitrogen atom-containing polymer, a formic acid trapping agent, a weather resistance stabilizer (e.g., a light stabilizer), and a mold release agent. The amount of these additives is usually 0.1 to 5.0 parts by weight based on 100 parts by weight of the polyacetal resin.
As the antioxidant, 1 or more hindered phenol-based antioxidants can be used. Specific examples thereof include n-octadecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) -propionate, n-octadecyl-3- (3 ' -methyl-5 ' -tert-butyl-4 ' -hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) -propionate, 1, 6-hexanediol-bis- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1, 4-butanediol-bis- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) -propionate], (a salt thereof, a hydrate thereof, and the like, Triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], tetrakis [ methylene-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate]methane, 3, 9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy } -1, 1-dimethylethyl]2, 4, 8, 10-tetraoxaspiro (5, 5) undecane, N, N ' -bis-3- (3 ', 5 ' -di-tert-butyl-4-hydroxyphenyl) propionylhexamethylenediamine, N, N ' -tetramethylenebis-3- (3 ' -methyl-5 ' -tert-butyl-4-hydroxyphenyl) Propionyldiamine, N ' -bis- [3- (3, 5-di-tert-butyl-4-hydroxyphenol) propionyl]hydrazine, N-salicyloyl-N ' -salicylidene hydrazine, 3- (N-salicyloyl) amino-1, 2, 4-triazole, N ' -bis [2- {3- (3, 5-di-butyl-4-hydroxyphenyl) propionyloxy } ethyl]hydroxyamide, and the like. These antioxidants may be used in combination of 1 kind or 2 or more kinds.
Examples of the polymer containing a formaldehyde-reactive nitrogen atom include polyamide resins such as nylon 4, 6, nylon 6, 10, nylon 6, 12 and nylon 12, and copolymers thereof, for example, nylon 6/6, 6/6, 10 and nylon 6/6, 12, and copolymers thereof, and further examples of copolymers of acrylamide and derivatives thereof, acrylamide and derivatives thereof and other ethylene monomers include poly- β -alanine copolymers obtained by polymerizing acrylamide and derivatives thereof and other ethylene monomers in the presence of a metal alkoxide, and these polymers containing a formaldehyde-reactive nitrogen atom may be used in 1 kind or in combination of 2 or more kinds.
Examples of the formic acid trapping agent include an amino-substituted triazine compound, an adduct of an amino-substituted triazine compound and formaldehyde, or a polycondensate of an amino-substituted triazine compound and formaldehyde.
Specific examples of the amino-substituted triazine compound include guanamine (2, 4-diamino-s-triazine), melamine (2, 4, 6-triamino-s-triazine), N-butylmelamine, N-phenylmelamine, N-diphenylmelamine, N-diallylmelamine, N', N "-triphenylmelamine, benzoguanamine (2, 4-diamino-6-phenyl-s-triazine), 2, 4-diamino-6-methyl-s-triazine, 2, 4-diamino-6-butyl-s-triazine, 2, 4-diamino-6-benzyloxy-s-triazine, 2, 4-diamino-6-butoxy-s-triazine, and, 2, 4-diamino-6-cyclohexyl-s-triazine, 2, 4-diamino-6-chloro-s-triazine, 2, 4-diamino-6-mercapto-s-triazine, 2, 4-dioxo-6-amino-s-triazine, 2-oxo-4, 6-diamino-s-triazine, N' -tetracyanoethylbenzoguanamine.
Specific examples of the adduct of an amino-substituted triazine compound and formaldehyde include N-methylolmelamine, N '-dimethylolmelamine, and N, N' -trimethylolmelamine.
Specific examples of the polycondensate of the amino-substituted triazine compound and formaldehyde include melamine-formaldehyde polycondensates.
These amino-substituted triazine compounds, adducts of amino-substituted triazine compounds and formaldehyde, or polycondensates of amino-substituted triazine compounds and formaldehyde may be used in 1 kind or in combination of 2 or more kinds.
Examples of the light stabilizer include 1 or more of benzotriazole-based ultraviolet absorbers and oxalylamide-based ultraviolet absorbers and hindered amine-based light stabilizers, examples of the benzotriazole-based ultraviolet absorbers include 2- (2 '-hydroxy-5' -methyl-phenyl) benzotriazole, 2- (2 '-hydroxy-3', 5 '-di-tert-butyl-phenyl) benzotriazole, 2- (2' -hydroxy-3 ', 5' -di-isopentyl-phenyl) benzotriazole, 2- [2 '-hydroxy-3', 5 '-bis- (α -dimethylbenzyl) phenyl]-2H-benzotriazole, 2- (2' -hydroxy-4 '-octyloxyphenyl) benzotriazole, 2-ethoxy-2' -ethyloxobenzene dicarboxanilide, 2-ethoxy-5-tert-butyl-2 '-ethyloxalic acid bisamide, 2-ethoxy-3' -laurylamide, 2-tetramethyl-2- [ 2-tetramethyl-4-2-tetramethyl-4, 6-piperidyl]-2, 6-tetramethyl-2-ethyl-2-piperidine, 6-tetramethyl-2-ethyl-2-piperidyl-2-6-ethyl-2-ethyl-2-6-ethyl-2-6-ethyl-2-6-dicarboximide, 6-bis (2-tetramethyl-phenyl) -2-tetramethyl-2-6-piperidyl) malonate, 6-methyl-2-tetramethyl-2-6-ethyl-2-ethyl-2-6-ethyl-2-6-2-ethyl-2-6-ethyl-2-6-ethyl-2-methyl-2-ethyl-2-ethyl-2-6-2-ethyl-2-ethyl-6-2-ethyl-2-ethyl-2-6-2-ethyl-6-2-ethyl-6-ethyl-2-ethyl-2-6-ethyl-2-ethyl-6-2-ethyl-6-ethyl-2-6-2-6-2-ethyl-2-ethyl-6-2-6-2-ethyl-6-2-6-2-ethyl-2-ethyl-6-2-6-methyl-ethyl-2-6-2-6-2-6-2-methyl-6-methyl-ethyl-2-methyl-2-ethyl-2-methyl-ethyl-6-ethyl-methyl-ethyl-2-ethyl-2-ethyl-2-6-2-ethyl-6-2-6-ethyl-6-2-6.
Examples of the release agent include at least one selected from fatty acid esters, polyalkylene glycols, and aliphatic compounds having an amide group. The fatty acid ester is a fatty acid ester compound composed of a polyhydric alcohol and a fatty acid, preferably at least 1 saturated fatty acid ester having 10 or more carbon atomsOr unsaturated fatty acids and, derived from polyols containing 2 to 6 carbon atoms. Examples of the polyhydric alcohol used in the production of the fatty acid ester compound include polyhydric alcohols selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, pentylene glycol, hexylene glycol, glycerin, and mixtures thereof,1 or more of diglycerol, triglycerol, threitol, erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbitol, sorbitan, sorbitol, and mannitol. Examples of the fatty acid include n-decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, and cerotic acid. Examples of unsaturated aliphatic carboxylic acids include undecylenic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassidic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearynoic acid, naturally occurring fatty acids containing such components, and mixtures thereof. These fatty acids may also be substituted with hydroxyl groups. Among the abovefatty acid ester compounds, preferred are fatty acid esters derived from a fatty acid selected from palmitic acid, stearic acid, behenic acid and montanic acid and a polyhydric alcohol selected from glycerin, pentaerythritol, sorbitan and sorbitol. These fatty acid esters may have a hydroxyl group or may not have a hydroxyl group, and are not particularly limited. For example, the compound may be a monoester, a diester, or a triester. Further, the hydroxyl group may be blocked with boric acid or the like. Preferred fatty acid ester compounds are: glycerol monopalmitate, glycerol dipalmitate, glycerol tripalmitate, glycerol monostearate, glycerol distearate, glycerol tristearate, glycerol monobehenate, glycerol dibehenate, glycerol tribehenate, glycerol monobehenate, glycerol ditehenate, glycerol tripalmitate, pentaerythritol monopalmitate, pentaerythritol dipalmitate, pentaerythritol tripalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, pentaerythritol monobehenate, pentaerythritol dibehenateEsters, pentaerythritol tribehenate, pentaerythritol tetrabehenate, pentaerythritol monobehenate, pentaerythritol dimontenate, pentaerythritol trimontenate, pentaerythritol tetramontenate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan tripalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monobehenate, sorbitan dibehenate, sorbitan tribehenate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitol tripalmitate, sorbitol distearate, sorbitol monostearate, sorbitan tristearate, sorbitol distearate, sorbitol tristearate, sorbitol monobehenate, sorbitol monodalmitate, sorbitol tripalmitate, sorbitol monopalmitate, sorbitol monostearate, sorbitol distearate, sorbitol tristearate, sorbitol monobehenate, Sorbitol dibehenate, sorbitol tribehenate, sorbitol mono-montanate, sorbitol di-montanate, and sorbitol tri-montanate. Further, as an example of the fatty acid ester compound having a hydroxyl group blocked withboric acid or the like, glycerin mono-fat can be mentionedBoric acid esters of acid esters (see Japanese patent application laid-open No. 49-60762). These fatty acid ester compounds may be used alone or in combination of 2 or more. As the polyalkylene glycol, a polyalkylene glycol represented by the following formula can be used
Figure A9519792400201
(in the formula, R1Selected from hydrogen, alkyl with 1-6 carbon atoms, substituted alkyl, allyl and substituted allyl, and each R1Each may be the same or different. X is 2-6 and Y is 1000-. Such polyalkylene glycols are obtainable by ring-opening polymerization of epoxides. Specific examples of the epoxide include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide, oxetane, 3-bis (chloromethyl) oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, and oxepane. These polyalkylene glycols may be used alone or in combination of 2 or more. As the aliphatic compound having an amide group, an aliphatic compound represented by the following general formula can be used.
Figure A9519792400202
(in the formula, R2，R4Is represented by C1-C30Alkyl of R3Is represented by C1-C30An alkylene group of (a). ) Specific examples thereof include ethylene bis stearamide, ethylene bis laurylamide, ethylene bis oleylamide, and ethylene bis erucamide. These aliphatic compounds having an amide group may be used alone or in combination of 2 or more.
The form of these additives when added may be powder or molten.
The method for producing the polyacetal resin composition of the present invention is not particularly limited. The resin composition of the present invention can be obtained by melting and kneading a stabilized polyacetal resin as an essential component, a specific metal salt of aliphatic carboxylic acid as defined herein, and, if desired, an additive as an optional component, usually in an extruder. The extruder in this case may be a single extruder or a double extruder. Further, an additive may be added during the polymerization of the polyacetal resin.
The temperature of the extruder is not particularly limited, and may be suitably selected from the range of 170 ℃ to 240 ℃.
The method for molding the composition of the present invention is not particularly limited, and the composition can be molded by any known method such as extrusion molding, injection molding, compression molding, vacuum molding, blow molding, and foam molding.
Best mode for carrying out the invention
The present invention will be described in detail below with reference to reference examples, examples and comparative examples, but the present invention is not limited to these examples.
Ppm,% by weight and parts by weight in the reference examples, examples and comparative examples are each, unless otherwise specified, expressed as ppm by weight,% by weight and parts by weight. The heat aging resistance, age discoloration resistance, and mold adhesion prevention of the composition of the present invention, and the method for quantifying the metal compound adhered to the surface of the metal salt of aliphatic carboxylic acid and the occluded metal compound were evaluated by the following methods.
(A) Thermal aging resistance (amount of formaldehyde gas generated from polyacetal resin):
3g of a terminal-stabilized polyacetal resin was placed in an aluminum container, and the resin was melted by heating at 230 ℃ for 60 minutes under a nitrogen stream (6 liters/hour), and the formaldehyde gas generated atthis time was absorbed into 1 mol/liter of an aqueous sodium sulfite solution, and the amount of the formaldehyde gas generated was determined by titration with 0.01 equivalent of sulfuric acid, and was expressed in ppm by weight based on the weight of the polyacetal resin.
(B) Thermal aging resistance (tensile strength retention):
a dumbbell-shaped test piece (20 mm. times.180 mm. times.3 mm) was molded under the following conditions and apparatus.
Molding machine: IS-80A manufactured by Toshiba machine (strain) of Japan
Cylinder temperature: 200 deg.C
Injection pressure: 60kg/cm2G
Injection time: 15 seconds
Cooling time: 25 seconds
Metal mold temperature: 70 deg.C
The tensile strength of the test piece thus obtained was measured at a tensile rate of 5 mm/min using an automatic measuring instrument AG-1000B manufactured by Shimadzu corporation of Japan. Further, the test piece molded in the same manner was heated in a Gill's aging oven at 150 ℃ for 500 hours to determine the tensile strength in the same manner as described above, and the tensile strength retention ratio with respect to the test piece which was not heated was determined.
(C) Aging discoloration resistance:
the test piece prepared in the same manner as described above was placed in a Gill aging oven heated to 150 ℃ for 500 hours, and the change in color at this time was measured according to JIS Z-8730 using Handy color tester HC-T manufactured by Suga tester, Japan. The aged discoloration degree was represented by the difference (Δ bL value) between the color tone of the polyacetal resin composition to be evaluated, to which the metal saltof aliphatic carboxylic acid was added, and the color tone of the polyacetal resin obtained in comparative example 1, to be described later, to which the metal salt of aliphatic carboxylic acid was not added.
(D) Measurement of the amount of the metal compound attached to the surface of the metal salt of aliphatic carboxylic acid and the amount of the occluded metal compound:
2 samples of the metal salt of aliphatic carboxylic acid were prepared in equal weight amounts. The 1 st sample was put into 10ml of pure water per 1g of the sample, and after 1 hour of ultrasonic treatment at room temperature, the metal salt of aliphatic carboxylic acid was filtered to obtain a filtrate, and the amount of metal compound (W) present on the surface of the metal salt of aliphatic carboxylic acid was determined by ion chromatography of metal ions in the filtrate using the following apparatus1)。
The counter ion of the metal compound contained in or attached to the metal salt of aliphatic carboxylic acid is at least 1 selected from hydroxyl ion and chloride ion, but the hydroxyl ion cannot be directly quantified by ion chromatography. However, since metal ions and chloride ions (which can be quantified by ion chromatography as in the case of metal ions) can be directly quantified, hydroxyl ions can also be quantified based on the quantitative values of metal ions or the quantitative values of metal ions and chloride ions. However, in the following reference examples, the kind of the metal salt of aliphatic carboxylic acid as a raw material in the production of the crude salt of aliphatic carboxylic acid metal or the negative ion of the metal compound as a reactant reacting with the metal salt of aliphatic carboxylic acid is known, and therefore, only the metal ion is quantified.
[ quantification of Metal ion having valence of 1 (sodium ion in the following reference example)]
The device comprises the following steps: conductivity detector Water 431 (manufactured by Waters corporation, USA)
Column: shim-pack IC-C1(150 mm. times.5.0 mm) (manufactured by Shimadzu Kagaku K.K.)
Amount of filtrate fed to the column: 10 μ l
Mobile phase: 5mmol HNO3(61% HNO30.51g of the aqueous solution was added to 1 liter of water
1.0 ml/min
[ quantification of Metal ions having a valence of 2 (calcium ion, magnesium ion and zinc ion in the following reference examples]
The device comprises the following steps: conductivity detector Water 431 (manufactured by Waters corporation, USA)
Column: Shim-Pack IC-C1(150 mm. times.5.0 mm) (manufactured by Shimadzu Kagaku K.K.)
Amount of filtrate fed to the column: 100 μ l
Mobile phase: 1mmol of ethylenediamine
1mmol tartaric acid
(prepared by adding 70. mu.l of ethylenediamine and 153.2mg of tartaric acid to water (total amount: 1 liter))
1.0 ml/min
On the other hand, the 2 nd metal salt of aliphatic carboxylic acid sample was put into 10ml of methanol per 1g of the sample, subjected to ultrasonic treatment at a temperature of 60 ℃ for 1 hour, and filtered to obtain a filtrate. The obtained filtrate was mixed with water at a ratio of 1: 1, and the metal ions in the obtained mixture were quantified by ion chromatography using the same apparatus as described above to determine the total amount (W) of the metal compound adhered to the surface of the 2 nd metal salt of aliphatic carboxylic acid sample and the occluded metal compound2). The amount of the metal compound occluded in the metal aliphatic carboxylic acid is determined by the following formula (W)2) Value minus (W)1) The value of (3).
(E) Prevention of mold adhesion:
the polyacetal resin composition of the present invention is molded by a molding machine under molding conditions.
Molding machine: IS-100E manufactured by Toshiba machine (strain) of Japan
Cylinder temperature: 210 deg.C
Metal mold temperature: 40 deg.C
Injection pressure: 70kg/cm2G
Injection time: 10 seconds
Cooling time: 10 seconds
And (3) back suction: 2mm
Then, the adhesion prevention of the model (the number of injections 500) was determined according to the following criteria
No model attachment occurred: o is
Adhesion occurs in the cavity and the gas release portion: x
Additives used in the following examples, as described below ① hindered phenol based antioxidants
c-1: triethylene glycol bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate
Amide compound of c-2 tetrakis [ methylene-3- (3 ', 5' -di-tert-butyl-4-hydroxyphenyl) propionate]methane ② as polymer (heat stabilizer) containing formaldehyde-reactive nitrogen atom
d-1: nylon 6, 6
d-2 Poly- β -alanine copolymer ③ formic acid trapping agent with a Primary amide content of 7mmol/1g Polymer
e-1: melamine
e-2 Melamine-Formaldehyde polycondensate (soluble in warm water at 60 ℃ C., soluble in dimethyl sulfoxide) ④ light stabilizer with a molecular weight of 700 and an average particle diameter of 50 μm
f-1: 2- [ 2-hydroxy-3, 5-bis (α -dimethylbenzyl) phenyl]-2H-benzotriazole
f-2: bis (2, 2, 6, 6-tetramethyl-4-piperidinyl) -sebacate
f-3: 1-12- {3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy } ethyl]-4- {3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy }2, 2, 6, 6-tetramethylpiperidine
Condensates of f-4: 1, 2, 3, 4-butanetetracarboxylic acid and 1, 2, 2, 6, 6-pentamethyl-4-piperidinol and β ', β' -tetramethyl-3, 9- [2, 4, 8, 10-tetraoxaspiro (5, 5) undecane]diethanol
f-5: 2-ethoxy-2' -ethyl oxalic acid bisanilide ⑤ mold release agent
g-1: glycerol monostearate
g-2: polyethylene glycol (molecular weight 6000)
g-3: ethylene bis stearamide
Reference example 1
[ preparation of polyacetal resin (a-1)]
A5 liter kneader equipped with a jacket capable of passing a heat carrier and having two stirring blades was set to 80 ℃ and 3kg of trioxane containing 15ppm of water and 4.0 mol% relative to 1mol of trioxane to which 100ppm of tetrakis [ methylene-3- (3 ', 5' -di-tert-butyl-4-hydroxyphenyl) propionate]1 part of the methane is obtained by the reaction,3-dioxolane, methylal 0.7X 10 as molecular weight regulator-3And (mol). To this mixture, 0.15 × 10 was added to 1mol of trioxane-4And (3) carrying out polymerization reaction by using mol of boron trifluoride dibutyl ether as a polymerization catalyst. After 30 minutes from the start of the reaction, 2 liters of an aqueous solution containing 1% triethylamine was introduced into the jacket by passing a heating medium at 30 ℃ to deactivate the catalyst for 1 hour to stop the reaction. Thereafter, the contents of the kneader were taken out and filtered, and the filter cake was dried at 100 ℃ to obtain 2.7kg of a polyacetal resin. The above operation was repeated until the total amount reached 10 kg. The resulting polyacetal resin was fed to a twin-screw extruder (L/D ratio: 32) having 1 vent of 30 mm. The polyacetal resin (a-1) having stabilized terminal was obtained in the form of pellets by stabilizing the terminal of the polyacetal resin and removing volatile substances under the conditions that the temperature of the extruder was 200 ℃, the amount of water injected into the reaction zone of the extruder and the amount of triethylamine used as a basic substance were 0.2 wt% and 0.1 wt% with respect to the resin, respectively, and the degree of vacuum in the vent was 200 torr. The polyacetal resin (a-1) thus obtained exhibited an amount of formaldehyde gas generation of 1100ppm and a melt index value of 10g/10 min.
[ preparation of polyacetal resin (a-2)]
The polyacetal resin (a-2) having stabilized terminal was obtained in substantially the same manner as in the preparation of the polyacetal resin (a-1) except that the vacuum degree of the vent hole of the extruder at the time of terminal stabilization of the polyacetal resin was 100 Torr. The polyacetal resin (a-2) thus obtained exhibited an amount of formaldehyde gas generation of 540ppm and a melt index value of 10g/10 min.
[ preparation of polyacetal resin (a-3)]
The polyacetal resin (a-3) having stabilized terminal was obtained in substantially the same manner as in the preparation of the polyacetal resin (a-1) except that the vacuum degree of the vent of the extruder at the time of terminal stabilization of the polyacetal resin was set to 30 Torr. The polyacetal resin (a-3) thus obtained exhibited an amount of formaldehyde gas generation of 260ppm and a melt index value of 10g/10 min.
[ production of polyacetal resin (a-4)]
Will be provided with a jacket through which a heat carrier can pass and 2 stirrersA5 liter kneader equipped with a paddle was adjusted to 80 ℃ and 3kg of trioxane containing 16ppm of water was added and mixed with 4.0 mol% of 1mol of trioxane to which 100ppm of tetrakis [ methylene-3- (3 ', 5' -di-tert-butyl-4-hydroxyphenyl) propionate was added]1, 3-dioxolane of methane, methylal as molecular weight regulator 0.7X 10-3And (mol). To this mixture, 0.15 × 10 was added to 1mol of trioxane-4And (3) carrying out polymerization reaction by using mol of boron trifluoride dibutyl ether as a polymerization catalyst. Reaction vesselAfter the start, 30 minutes, a heating medium at 30 ℃ was passed through the jacket, and 2 liters of an aqueous solution containing 1% triethylamine was added to deactivate the catalyst for 1 hour to stop the reaction. Thereafter, the contents of the kneader were taken out, and the filter cake was dried at 100 ℃ to obtain 2.7kg of a polyacetal resin. The above operation was repeated until the total amount reached 10 kg. To 100 parts of the obtained polyacetal resin, 0.3 part of triethylene glycol-bis- [3- ((3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate was added, a twin-screw extruder (L/D ratio: 32) having 1 vent of 30mm was supplied, the extruder temperature was 200 ℃, water injected into the reaction zone of the extruder and the amount of triethylamine used as a basic substance were added, the terminal stabilization and the volatile removal of the polyacetal resin were carried out under conditions of 0.2 wt% and 0.1 wt% of the resin and the degree of vacuum of the vent of 100 Torr, respectively, and the polyacetal resin (a-4) having stabilized terminals was obtained in the form of pellets, the formaldehydegas generation amount of the obtained polyacetal resin (a-4) was 560ppm, and the melt index value was 10g/10 min.
The formaldehyde gas generation amounts and melt index values of the obtained polyacetal resins (a-1) to (a-4) are shown in Table 1 below.
TABLE 1
Kinds of polyacetal resins Melt index value (g/10 min) Amount of Formaldehyde produced (ppm)
a-1 10 1100
a-2 10 540
a-3 10 260
a-4 10 560
Reference example 2
[ preparation of Metal salt of aliphatic Carboxylic acid (b-1)]
57g of stearic acid was added to 1000ml of pure water heated to 80 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 50 ℃ and then 7.8g of calcium hydroxide was suspended in 20ml of pure water and the suspension was added. The amount of calcium hydroxide added was 1.05 mol based on 2 mol of stearic acid. The resulting mixture was again heated to 80 ℃ and aged for 1 hour to effect a reaction.
Then, the reaction mixture is naturally cooled to room temperature, filtered and dehydrated to obtain a crude calcium stearate product. The obtained crude calcium stearate was washed with water under stirring for 1 hour, and then filtered and dehydrated (water washing treatment). This washing treatment was repeated until W1(amount of calcium hydroxide adhering to the surface of calcium stearate) was 10ppm, W2(the total amount of calcium hydroxide adhering to the surface of calcium stearate and calcium hydroxide occluded in the calcium stearate) was 275ppm of the desired calcium stearate. W1And W2The above-mentioned method according to the item (D). The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-1).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-2)]
Except that the above water washing treatment was repeated until W was obtained1＝0，W2The procedure was carried out in substantially the same manner as in the preparation of the metal salt of aliphatic carboxylic acid (b-1), except that 48ppm of calcium stearate was used. The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-2).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-3)]
Except that the above water washing treatment was repeated until W was obtained1＝0，W2The procedure was substantially the same as for the preparation of the metal salt of aliphatic carboxylic acid (b-1), except that 4ppm of calcium stearate was used. The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-3).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-4)]
Except that the above water washing treatment was repeated until W was obtained1＝0、W2The procedure was substantially the same as for the preparation of the metal salt of aliphatic carboxylic acid (b-1), except for 0 of calcium stearate. The desired calcium stearate is used as aliphaticA carboxylate metal salt (b-4).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-5)]
57g of stearic acid was added to 1000ml of pure water heated to 80 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 50 ℃ and then an aqueous sodium hydroxide solution obtained by adding 8.4g of sodium hydroxide to 40ml of pure water was added. The amount of sodium hydroxide added was 1.05 mol based on 1mol of stearic acid. The resulting mixture was again heated to 80 ℃ and aged for 1 hour to effect a reaction.
Thereafter, the reactionmixture was cooled to room temperature, filtered and dehydrated (water washing treatment). Thereafter, the water washing treatment was repeated 2 times. 40g of the obtained sodium stearate was added again to 1000ml of pure water heated to 80 ℃ and dissolved with stirring, and an aqueous solution obtained by dissolving 7.5g of calcium chloride in 20ml of pure water was added thereto. The amount of calcium chloride added was 1.05 mol based on 2 mol of sodium stearate. After 1 hour, filtration and dehydration were carried out to obtain a crude calcium stearate product. Repeatedly washing the obtained calcium stearate crude product with water until W is obtained1(amount of calcium chloride and sodium chloride adhering to the surface of calcium stearate) was 7ppm, W2(the total amount of calcium chloride and sodium chloride adhering to the surface of calcium stearate and calcium chloride and sodium chloride occluded in the calcium stearate) was 112ppm of the desired calcium stearate. W1And W2The above-mentioned results are obtained by the method of the above item (D). The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-5).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-6)]
40g of lauric acid was added to 1000ml of pure water heated to 50 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 25 ℃ and then a suspension obtained by suspending 7.8g of calcium hydroxide in 20ml of pure water was added. The amount of calcium hydroxide added was 1.05 mol based on 2 mol of lauric acid. The reaction mixture was heated to 50 ℃ again, and aged for 1 hour to effect a reaction.
And then, naturally cooling the reaction mixed solution to room temperature, filtering and dehydrating to obtain the calcium laurate product. For the obtained crude calcium laurateThe product was washed with water under stirring for 1 hour, and then filtered and dehydrated (water washing treatment). This washing treatment was repeated until W was obtained1(amount of calcium hydroxide adhering to the surface of calcium laurate) was 13ppm, and W was2(the total amount of calcium hydroxide attached to the surface of calcium laurate and calcium hydroxide occluded in the calcium laurate) was 281ppm of the desired calcium laurate. W1And W2The above-mentioned method according to the item (D). The desired calcium laurate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-6).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-7)]
60g of behenic acid was added to 1000ml of pure water heated to 90 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 50 ℃ and then a suspension obtained by suspending 6.8g of calcium hydroxide in 20ml of pure water was added. The amount of calcium hydroxide added was 1.05 mol based on 2 mol of behenic acid. The resulting mixture was again heated to 90 ℃ and aged for 1 hour to effect a reaction.
Thereafter, the reaction mixture was cooled to room temperature, filtered and dehydrated to obtain a crude calcium behenate product. The mixture was stirred and washed with water for 1 hour, and then filtered and dehydrated (water washing treatment). This washing treatment was repeated until W was obtained1(calcium hydroxide adhered to the surface of calcium behenateAmount) of 10ppm, W2(total amount of calcium hydroxide adhering to the surface of calcium behenate and calcium hydroxide occluded in the calcium behenate) was 294ppm of the desired calcium behenate. W1And W2The above-mentioned method according to the item (D). The desired calcium laurate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-7).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-8)]
57g of stearic acid was added to 1000ml of pure water heated to 80 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 50 ℃ and then a suspension obtained by suspending 6.1g of magnesium hydroxide in 20ml of pure water was added. The amount of magnesium hydroxide added was 1.05 mol based on 2 mol of stearic acid. The resulting mixture was again heated to 80 ℃ and aged for 1 hour to effect a reaction.
Thereafter, the reaction is carried outAnd naturally cooling the mixed solution to room temperature, filtering and dehydrating to obtain a magnesium stearate crude product. The obtained magnesium stearate crude product was stirred for 1 hour and washed with water, and then filtered and dehydrated (water washing treatment). This washing treatment was repeated until W was obtained1(amount of magnesium hydroxide adhering to the surface of magnesium stearate) was 17ppm, W2(the total amount of magnesium hydroxide adhering to the surface of magnesium stearate and magnesium hydroxide occluded in magnesium stearate) was 281ppm of the desired magnesium stearate. W1And W2The above-mentioned method according to the item (D). The desired magnesium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-8).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-9)]
57g of stearic acid was added to 1000ml of pure water heated to 80 ℃ and stirred to obtain an emulsion. The resulting emulsion was cooled to 50 ℃ and then a suspension obtained by suspending 10.4g of zinc hydroxide in 20ml of pure water was added. The amount of zinc hydroxide added was 1.05 mol based on 2 mol of stearic acid. The resulting mixture was again heated to 80 ℃ and aged for 1 hour to effect a reaction.
Then, the reaction mixture is naturally cooled to room temperature, filtered and dehydrated to obtain a crude zinc stearate product. The obtained zinc stearate crude product was stirred and washed with water for 1 hour, and then filtered and dehydrated (water washing treatment). This washing treatment was repeated until W was obtained1(amount of zinc hydroxide adhering to surface of zinc stearate) was 15ppm, W2(the total amount of zinc hydroxide attached to the surface of zinc stearate and zinc hydroxide occluded in zinc stearate) was 263ppm of the desired zinc stearate. W1And W2The above-mentioned method according to the item (D). The desired zinc stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-9).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-10)]
500g of the metal salt of aliphatic carboxylic acid (b-3)(b-3) calcium hydroxide (260 ppm) was added, and it was charged into a small-sized (Henschel) mixer of 3 liter capacity, and the jacket temperature of the small-sized Henschel mixer was raised so that the content temperature reached 40 ℃. After thatAnd then, the mixture was blended at 860rpm for 5 minutes and discharged, thereby obtaining a metal salt of aliphatic carboxylic acid (b-10) having calcium hydroxide attached to the surface of the metal salt of aliphatic carboxylic acid (b-3). The reason why the calcium hydroxide is attached to the surface without being occluded in the metal salt of aliphatic carboxylic acid (b-3) is because the metal salt of aliphatic carboxylic acid does not dissolve at a temperature of 40 ℃. Amount (W) of calcium hydroxide to be present on the surface of the obtained metal salt of aliphatic carboxylic acid (b-10)1) The content of the polycarbonate was determined to be 250 ppm.
[ preparation of Metal salt of aliphatic Carboxylic acid (b-11)]
Except that the water washing treatment is repeated until W is obtained1＝0、W2The procedure was substantially the same as that for the preparation of the metal salt of aliphatic carboxylic acid (b-1), except that 1ppm of calcium stearate was used. The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-11).
[ preparation of Metal salt of aliphatic Carboxylic acid (b-12)]
Except that the water washing treatment is repeated until W is obtained1＝31ppm、W2The procedure was substantially the same as that for the preparation of the metal salt of aliphatic carboxylic acid (b-1), except that 851ppm of calcium stearate was used. The desired calcium stearate thus obtained was used as the metal salt of aliphatic carboxylic acid (b-12).
Table 2 shows the amounts (W) of the metal compounds attached to the surfaces of the obtained metal salts of aliphatic carboxylic acid (b-1) to (b-12)1) The total amount (W) of the metal compound attached to the surface and the occluded metal compound2) And the amount of the metal compound (W) to be occluded2-W1)。
TABLE 2
Aliphatic carboxylic acidsKinds of metal salts Metal compound attached to surface and occluded metal compound
Species of Amount of adhesion to the surface (W1)(ppm) Amount of adhesion to the surface And amount of the occluded Total amount of (W2)(ppm) The amount of the occluded substance (W2-W1)(ppm)
b-1 Calcium stearate Ca(OH)2 10 275 265
b-2 Calcium stearate Ca(OH)2 0 48 48
b-3 Calcium stearate Ca(OH)2 0 4 4
b-4 Calcium stearate Ca(OH)2 0 0 0
b-5 Calcium stearate CaCl2 NaCl 7 112 105
b-6 Calcium laurate Ca(OH)2 13 281 268
b-7 Calcium behenate Ca(OH)2 10 294 284
b-8 Magnesium stearate Mg(OH)2 17 281 264
b-9 Zinc stearate Zn(OH)2 15 263 248
b-10 Calcium stearate Ca(OH)2 250 254 4
b-11 Calcium stearate Ca(OH)2 0 1 1
b-12 Calcium stearate Ca(OH)2 31 851 820
[ note)]*The metal salt of aliphatic carboxylic acid (b-10) is according to the metal salt of aliphatic carboxylic acid (b-3)
Treating the metal salt of aliphatic carboxylic acid with calcium hydroxide such that 250ppm of calcium hydroxide is attached to the surface
(b-3).
Example 1
1.5kg of a polyacetal resin (a-1) having a formaldehyde gas generation amount of 1100ppm and 0.1 part of a metal salt of an aliphatic carboxylic acid (b-3) per 100 parts of the polyacetal resin (a-1) were charged into a small Henschel mixer having a volume of 3 liters. The jacket temperature of the small Henschel mixer was increased so that the content temperature reached 40 ℃. Thereafter, the mixture was discharged after mixing at 860rpm for 2 minutes. This operation was repeated until the total amount was 10 kg. The resulting mixture was fed to a twin-screw extruder (L/D ratio: 32) provided with 1 vent of 30 mm. The extrusion was carried out under conditions of an extruder temperature of 200 ℃ and a discharge rate of 5 kg/hr, a screw rotation number of 100rpm, and a vent vacuum of 30 Torr. The discharged polyacetal resin composition was pelletized with a cutter. The pelletized polyacetal resin compositionwas dried at 80 ℃ for 5 hours, and then put into a molding machine IS-80A of Toshiba machine (Co., Ltd.) of Japan to be molded into a dumbbell-shaped test piece (20 mm. times.180 mm. times.3 mm). The molding conditions were that the cylinder temperature was 200 ℃ and the injection pressure was 60kg/cm2G. Injection time 15 seconds, cooling time 25 seconds, mold temperature 70 ℃. The test piece thus obtained was placed in a thermostatic chamber at 23 ℃ and a relative humidity of 50% for 2 days, and thereafter the heat aging resistance and the aging discoloration resistance and the mold adhesion prevention were evaluated. The results are shown in Table 3.
Examples 2 to 6 and comparative examples 1 and 2
Substantially the same operation as in example 1 was carried out, except that the addition amount of the metal salt of aliphatic carboxylic acid was changed as shown in table 3. The results are shown in Table 3.
Examples 7 to 13
Substantially the same operation as in example 1 was carried out, except that the kind of the metal salt of aliphatic carboxylic acid was changed as shown in table 3. The results are shown in Table 4.
Example 14
Substantially the same operation as in example 1 was carried out, except that the polyacetal resin (a-2) having a formaldehyde emission of 540ppm was used. The results are shown in Table 4.
Example 15
Substantially the same operation as in example 1 was carried out, except that the polyacetal resin (a-3) having a formaldehyde emission of 260ppm was used. The results are shown in Table 4.
Comparative example 3
Substantially the same operation as in example 1 was conducted, except that the metal salt of aliphatic carboxylicacid (b-4) not occluding the metal compound was used. The results are shown in Table 4.
Comparative example 4
Substantially the same operation as in example 1 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in Table 4.
Example 16
A test piece of a polyacetal resin composition was prepared in substantially the same manner as in example 1, except that 1.5kg of a polyacetal resin (a-1) having a formaldehyde emission of 1100ppm, 0.03 part of a metal salt of an aliphatic carboxylic acid (b-3) per 100 parts of the polyacetal resin (a-1), 0.2 part of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]as a hindered phenol-based antioxidant, 6. 60.025 parts of nylon, and 0.1 part of glycerol monostearate were charged into a small-sized Henschel mixer having a volume of 3 liters. The test pieces thus obtained were evaluated for heat aging resistance, age discoloration resistance and mold adhesion prevention. The results are shown in Table 5.
Example 17
Substantially the same operation as in example 16 was conducted, except that the polyacetal resin (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in Table 5.
Comparative example 5
Substantially the same operation as in example 16 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in Table 5.
Example 18
A test piece of a polyacetal resin composition was prepared in substantially the same manner as in example 1, except that 1.5kg of a polyacetal resin (a-1) having an amount of formaldehyde gas emission of 1100ppm, 0.1 part of a metal salt of an aliphatic carboxylic acid (b-3), 0.3 part of tetrakis [ methylene-3- (3 ', 5 ' -di-tert-butyl-4 ' -hydroxyphenyl) propionate]methane as a hindered phenol-based antioxidant, and 0.2 part of ethylene bis-stearamide were charged into a small-sized Henschel mixer having a volume of 3 liters, to thereby prepare a test piece of the polyacetal resin composition, based on 100 parts of the polyacetal resin (a-1). The test pieces thus obtained were evaluated for heat aging resistance, age discoloration resistance and mold adhesion prevention. The results are shown in Table 5
Example 19
Substantially the same operation as in example 18 was conducted, except that the polyacetal resin (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in Table 5.
Comparative example 6
Substantially the same operation as in example 18 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in Table 5.
Example 20
1.5kg of a polyacetal resin (a-1) having a formaldehyde emission amount of 1100ppm, 0.2 part of a metal salt of an aliphatic carboxylic acid (b-3), 0.3 part of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]as a hindered phenol-based antioxidant, 6.60.05 parts of nylon, 0.2 part of glycerol monostearate, 0.6 part of polyethylene glycol (molecular weight: 6000), and 0.3 part of melamine were charged into a small-sized Henschel mixer having a volume of 3 liters, and test pieces of a polyacetal resin composition were prepared in substantially the same manner as in example 1. The test pieces obtained were evaluated for heat aging resistance, age discoloration resistance and mold adhesion resistance.
Example 21
Substantially the same operation as in example 20 was conducted, except that the polyacetal resin (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in table 6.
Comparative example 7
Substantially the same operation as in example 20 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in table 6.
Example 22
A polyacetal resin composition test piece was prepared in substantially the same manner as in example 1 by charging 1.5kg of a polyacetal resin (a-1) having a formaldehyde gas generating amount of 1100ppm, 0.05 part of a metal salt of an aliphatic carboxylic acid (b-3), 0.60.05 part of nylon, 0.35 part of ethylenebisstearamide, 0.5 part of 2- [ 2-hydroxy-3, 5-bis (α -dimethylbenzyl) phenyl]-2H-benzotriazole, 0.25 part of bis (2, 2, 6, 6-tetramethyl-4-piperidyl) -sebacate, and 0.3 part of melamine into a small-sized Henschel mixer having a volume of 3 liters, and the heat aging resistance, aging discoloration resistance, and mold adhesion prevention of the test piece were evaluated, and the results are shown in Table 7.
Example 23
Substantially the same operation as in example 22 was conducted, except that the polyacetal (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in Table 7.
Comparative example 8
Substantially the same operation as in example 22 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in Table 7.
Example 24
1.5kg of a polyacetal resin (a-1) having a formaldehyde gas generating amount of 1100pm, 0.05 part of a metal salt of an aliphatic carboxylic acid (b-3), 6.60.1 parts of nylon, 0.3 part of triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate]as a hindered phenol-based antioxidant, and 0.075 part of 1- [2- {3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy } ethyl]-4- {3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy }2, 2, 6, 6-tetramethylpiperidine were charged into a three-liter-volume small Henschel mixer, based on 100 parts of the polyacetal resin (a-1), a polyacetal resin composition was obtained in substantially the same manner as in example 1. The test pieces obtained were evaluated for heat aging resistance, age discoloration resistance and mold adhesion prevention. The results are shown in table 8.
Example 25
Substantially the same operation as in example 24 was conducted, except that the polyacetal resin (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in table 8.
Comparative example 9
Substantially the same operation as in example 24 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in table 8.
Example 26
1.5kg of a polyacetal resin (a-1) having a formaldehyde gas generation amount of 1100ppm, 0.05 part of a metal salt of an aliphatic carboxylic acid (b-3), 0.5 part of nylon 6, 60.05 parts of ethylene bis stearamide, 0.05 part of 2- [ 2-hydroxy-3, 5-bis (α -dimethylbenzyl) phenyl]-2H-benzotriazole, 0.5 part of bis (2, 2, 6, 6-tetramethyl-4-piperidinyl) -sebacate, 1.0 part of polyethylene glycol (molecular weight 6000), 0.3 part of melamine, and 0.25 part of a condensate of 1, 2, 3, 4-butanetetracarboxylic acid and 1, 2, 2, 6, 6-pentamethyl-4-piperidinol and β ', β' -tetramethyl-3, 9- [2, 4, 8, 10-tetraoxaspiro (5, 5) undecane]diethanol were put into a small-sized Henschel mixer having a volume of 3 liters, and subjected to a test for the adhesion resistance of a polyacetal resin sheet according to the method substantially the same as that is described in example 1, and the results of the polyacetal resin (a) of the aging resistance test.
Example 27
Substantially the same operation as in example 26 was carried out, except that the polyacetal resin (a-3) having an amount of formaldehyde gas generated of 260ppm was used. The results are shown in Table 9.
Comparative example 10
Substantially the same operation as in example 26 was carried out, except that the metal salt of aliphatic carboxylic acid (b-10) obtained by attaching 250ppm of calcium hydroxide to the surface of the metal salt of aliphatic carboxylic acid (b-3) was used. The results are shown in Table 9.
Example 28
Substantially the same operation as in example 17 was conducted except that 0.1 part of poly- β -alanine copolymer having a primary amide content of 7mmol/1g of polymer was used in place of nylon 6, 60.025 parts, the results are shown in Table 10.
Example 29
Substantially the same operation as in example 27 was conducted, except that 0.3 part of melamine-formaldehyde polycondensate having a molecular weight of 700, an average particle diameter of 50 μm and a solubility in warm water at 60 ℃ and a solubility in dimethyl sulfoxide was used in place of 0.3 part of melamine. The results are shown in Table 10.
Example 30
Substantially the same operation as in example 23 was conducted, except that 0.5 part of 2-ethoxy-2' -ethyloxalic acid bisanilide was used instead of 0.5 part of 2- [ 2-hydroxy-3, 5-bis (α -dimethylbenzyl) phenyl]-2H-benzotriazole, the results of which are shown in Table 10.
Example 31
Substantially the same operation as in example 1 was conducted, except that the polyacetal resin (a-4) having a formaldehyde emission of 560ppm was used. The results are shown in Table 10.
Example 32
Substantially the same operation as in example 1 was conducted, except that the metal salt of aliphatic carboxylic acid (b-11) was used. The results are shown in Table 11.
Comparative example 11
Substantially the same operation as in example 1 was conducted, except that the metal salt of aliphatic carboxylic acid (b-12) was used. The results are shown in Table 11.
As is clear from tables 3 to 11, the compositions of the present invention comprising a polyacetal resin and a metal salt of aliphatic carboxylic acid having a specific amount of a metal compound in an occluded state and having a limited specific amount of a metal compound in a state of not having or being attached to the surface thereof are excellent in heat aging resistance, age discoloration resistance and mold adhesion prevention.
Evaluation of light resistance
To 100 parts of pellets of the polyacetal resin compositions obtained in examples 22, 23, 24, 25, 26, 27, 29 and 30, 0.2 part of carbon black (acetylene black) was mixed and melt-kneaded by a 30mm single-screw extruder (non-vented, L/D ratio: 22). The extrusion temperature at this time was 200 ℃, the screw rotation number was 100rpm, and the discharge amount was 3 kg/hour. The obtained colored pellets were dried at 80 ℃ for 5 hours and then molded into a flat plate having a length of 67mm, a width of 13mm and a thickness of 3mm by an injection molding machine. The molding machine and molding conditions used at this time are as follows.
Molding machine: IS-100E-3A manufactured by Toshiba machine (strain) of Japan
Cylinder temperature: 200 deg.C
Injection pressure: 40kg/cm2G
Injection time: 15 seconds
Cooling time: 25 seconds
Metal mold temperature: 70 deg.C
The plate thus obtained was subjected to a light resistance test under the following conditions, and the color difference (. DELTA.E) after light resistance exposure was observed in accordance with JIS Z8730 using the following apparatus.
(lightfastness test)
Testing machine: model EL-SUN-HC-B.EM fading meter manufactured by Suga testing machine (Inc.) of Japan
Temperature of carbon black sheet: 83 deg.C
Exposure time: 400 hours
(color difference)
Testing machine: Hc-T test machine manufactured by Suga test machine (strain)of Japan
The light irradiation surface of the plate was observed with a microscope at a magnification of 100 to observe the presence or absence of cracks.
As a result, the color difference (. DELTA.E) of any of the samples was not changed, and the occurrence of cracks was not observed.
TABLE 3
Polyacetal resin Aliphatic carboxylic acid metal salt After aging (150 ℃ C., 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Addition amount (parts) Retention of tensile strength Degree of discoloration (Δ bL value)
Example 1 a-1 100 b-3 0.1 100％ 1.6 ○
Example 2 a-1 100 b-3 0.01 100％ 1.4 ○
Example 3 a-1 100 b-3 0.3 100％ 1.7 ○
Example 4 a-1 100 b-3 0.5 100％ 1.9 ○
Example 5 a-1 100 b-3 1.0 100％ 2.6 ○
Example 6 a-1 100 b-3 3.0 100％ 3.0 ○
Comparative example 1 a-1 100 Is free of Is free of 75％ 0 ○
Comparative example 2 a-1 100 b-3 5.0 100％ 4.7 ×
TABLE 4
Polyacetal resin FatMetal salt of group carboxylic acid After aging (150 ℃ C., 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Addition amount (parts) Retention of tensile strength Degree of discoloration (Δ bL value)
Example 7 a-1 100 b-1 0.1 100％ 2.9 ○
Example 8 a-1 100 b-2 0.1 100％ 1.9 ○
Example 9 a-1 100 b-5 0.1 100％ 2.4 ○
Example 10 a-1 100 b-6 0.1 100％ 2.9 ○
Example 11 a-1 100 b-7 0.1 100％ 2.7 ○
Example 12 a-1 100 b-8 0.1 100％ 2.4 ○
Example 13 a-1 100 b-9 0.1 100％ 2.5 ○
Example 14 a-2 100 b-3 0.1 100％ 1.2 ○
Example 15 a-3 100 b-3 0.1 100％ 0.9 ○
Comparative example 3 a-1 100 b-4 0.1 93％ 1.4 ○
Comparative example 4 a-1 100 b-10 0.1 100％ 4.2 ×
TABLE 5
Polyacetal resin Aliphatic carboxylic acid metal salt Oxidation preventive Amide compound Release agent After aging (150 ℃ C., 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) The kind of the same. Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of discoloration (Δ bL value)
Example 16 a-1 100 b-3 0.03 c-1 0.2 d-1 0.025 g-1 0.1 100％ 1.8 ○
Example 17 a-3 100 b-3 0.03 c-1 0.2 d-1 0.025 g-1 0.1 100％ 0.9 ○
Comparative example 5 a-1 100 b-10 0.03 c-1 0.2 d-1 0.025 g-1 0.1 100％ 4.8 ×
Example 18 a-1 100 b-3 0.1 c-2 0.3 g-3 0.2 100％ 1.8 ○
Example 19 a-3 100 b-3 0.1 c-2 0.3 g-3 0.2 100％ 1.0 ○
Comparative example 6 a-1 100 b-10 0.1 c-2 0.3 g-3 0.2 100％ 5.4 ×
TABLE 6
Polyacetal resin Aliphatic carboxylic acid metal salt Oxidation preventive Amide compound Formic acid trapping agent Release agent Aging (150 c, 500 hours) after Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of color change (Δ bL value)
Example 20 a-1 100 b-3 0.2 c-1 0.3 d-1 0.05 e-1 0.3 g-1 g-2 0.2 0.6 100％ 2.1 ○
Example 21 a-3 100 b-3 0.2 c-1 0.3 d-1 0.05 e-1 0.3 g-1 g-2 0.2 0.6 100％ 1.1 ○
Comparative example 7 a-1 100 b-10 0.2 c-1 0.3 d-1 0.05 e-1 0.3 g-1 g-2 0.2 0.6 100％ 5.6 ×
TABLE 7
Polyacetal resin Aliphatic carboxylic acid metal salt Amide composition Amide compound Light stabilizers Release agent Aging (150 ℃ C.,) 500 hours) after Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of color change (Δ bL value)
Example 22 a-1 100 b-3 0.05 d-1 0.05 e-1 0.3 f-1 f-2 0.5 0.25 g-3 0.35 100％ 5.5 ○
Example 23 a-3 100 b-3 0.05 d-1 0.05 e-1 0.3 f-1 f-2 0.5 0.25 g-3 0.35 100％ 4.1 ○
Comparative example 8 a-1 100 b-10 0.05 d-1 0.05 e-1 0.3 f-1 f-2 0.5 0.25 g-3 0.35 100％ 8.4 ×
TABLE 8
Polyacetal resin Aliphatic carboxylic acid metal salt Oxidation preventive Amide compound Light stabilizers Aging (150 c, 500 hours) after Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of color change (Δ bL value)
Example 24 a-1 100 b-3 0.05 c-1 0.3 d-1 0.1 f-3 0.075 100％ 2.8 ○
Example 25 a-3 100 b-3 0.05 c-1 0.3 d-1 0.1 f-3 0.075 100％ 1.6 ○
Comparative example 9 a-1 100 b-10 0.05 c-1 0.3 d-1 0.1 f-3 0.075 100％ 5.7 ×
TABLE 9
Polyacetal resin Aliphatic carboxylic acid metal salt Amide compound Formic acid trapping agent Light stabilizers Release agent Aging (150 c, 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of color change (Δ bL value)
Example 26 a-1 100 b-3 0.05 d-1 0.05 e-1 0.3 f-1 f-2 f-4 0.5 0.25 0.25 g-2 g-3 1.0 0.05 100％ 5.7 ○
Example 27 a-3 100 b-3 0.05 d-1 0.05 e-1 0.3 f-1 f-2 f-4 0.5 0.25 0.25 g-2 g-3 1.0 0.05 100％ 4.2 ○
Comparative example 10 a-1 100 b-10 0.05 d-1 0.05 e-1 0.3 f-1 f-2 f-4 0.5 0.25 0.25 g-2 g-3 1.0 0.05 100％ 9.2 ×
Watch 10
Polyacetal resin Aliphatic carboxylic acids Metal salt Oxidation preventive Amide compound Formic acid trapping agent Light stabilizers Release agent Aging (150 c, 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Species of Adding amount of (share) Tensile strength Retention rate Degree of color change (Δ bL value)
Example 28 a-3 100 b-3 0.03 c-1 0.2 d-2 0.1 g-1 0.1 100％ 1.0 ○
Example 29 a-3 100 b-3 0.05 d-1 0.05 e-2 0.3 f-1 f-2 f-4 0.5 0.25 0.25 g-2 g-3 1.0 0.05 100％ 4.4 ○
Example 30 a-3 100 b-3 0.05 d-1 0.05 e-1 0.3 f-5 f-2 0.5 0.25 g-3 0.35 100％ 4.2 ○
Example 31 a-4 100 b-3 0.1 100％ 1.0 ○
TABLE 11
Polyacetal resin Aliphatic carboxylic acid metal salt After aging (150 ℃ C., 500 hours) Model for preventing from being damaged Adhesion Property
Species of Quantity (parts) Species of Adding amount of (share) Retention of tensile strength Degree of discoloration (Δ bL value)
Example 32 a-1 100 b-11 0.1 100％ 1.5 ○
Comparative example 11 a-1 100 b-12 0.1 100％ 4.0 ○
Possibility of industrial utilization
The polyacetal resin composition of the present invention has excellent thermal aging resistance and age discoloration resistance, and solves the problems of poor physical properties and poor appearance caused by using a molded article comprising a conventional polyacetal resin in a high-temperature atmosphere. Further, since the polyacetal resin composition of the present invention is also excellent in mold adhesion prevention, molding productivity is improved. The polyacetal resin composition of the present invention can be suitably used for various applications, particularly for the production of mechanical parts used for a long period of time under high temperature conditions.

Claims (10)

1. A polyacetal resin composition obtained by adding 0.01 to 3.0 parts by weight of at least 1 metal salt of an aliphatic carboxylic acid to 100 parts by weight of a terminal-stabilized polyacetal resin;
characterized in that the metal salt of aliphatic carboxylic acid has at least 1 metal compound selected from the group consisting of metal hydroxides and metal chlorides in a occluded state, and the metal salt of aliphatic carboxylic acid has at least 1 metal compound selected from the group consisting of metal hydroxides and metal chlorides in a state of being attached to the surface thereof, and the amount of the at least 1 occluded metal compound and the amount of the at least 1 metal compound attached to the surface are 1 to 300 ppm by weight and 0 to 20ppm by weight, respectively, relative to the total weight of the metal salt of aliphatic carboxylic acid, the metal compound occluded and the metal compound attached to the surface.
2. The polyacetal resin composition according to claim 1, wherein the metal of the at least 1 metal salt of an aliphatic carboxylic acid is selected from the group consisting of calcium, magnesium, barium, zinc, and strontium.
3. The polyacetal resin composition according to claim 1, wherein the metal of the at least 1 metal compound contained in the metal salt of aliphatic carboxylic acid is selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, zinc and strontium.
4. The polyacetal resin composition according to claim 1, wherein the amount of formaldehyde gas generated when the terminal-stabilized polyacetal resin is heated at 230 ℃ for 60 minutes under a nitrogen stream is 600 ppm by weight or less relative to the weight of the terminal-stabilized polyacetal resin.
5. The polyacetal resin composition according to claim 1, further comprising 0.1 to 5.0 parts by weight of at least one additive selected from an antioxidant, a polymer containing a formaldehyde-reactive nitrogen atom, a formic acid trapping agent, a light stabilizer and a mold release agent.
6. The polyacetal resin composition as set forth in claim 5, wherein at least 1 of the antioxidants is a hindered phenol-based antioxidant.
7. The polyacetal resin composition according to claim 5, wherein the polymer containing a formaldehyde-reactive nitrogen atom is at least one selected from the group consisting of polyamide resins, polyacrylamides and derivatives thereof, and copolymers of acrylamide and other vinyl monomers.
8. The polyacetal resin composition according to claim 5, wherein the formic acid trapping agent is at least one selected from the group consisting of an amino-substituted triazine compound, an adduct of an amino-substituted triazine compound and formaldehyde, and a polycondensate of an amino-substituted triazine compound and formaldehyde.
9. The polyacetal resin composition according to claim 5, wherein the light stabilizer is at least 1 selected from the group consisting of benzotriazole-based ultraviolet absorber, oxalanilide-based ultraviolet absorber, and hindered amine-based light stabilizer.
10. The polyacetal resin composition according to claim 5, wherein the release agent is at least one selected from the group consisting of fatty acid esters, polyalkylene glycols, and aliphatic compounds having amide groups.
CN95197924A 1995-09-29 1995-09-29 Polyacetal resin composition Expired - Lifetime CN1109072C (en)

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