JP2011032379A - Polyacetal resin composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin composition that has highly excellent resistance against heat, solvent, acidity, etc. and is especially suitable for such uses requiring excellent durability for being used contacting with a bio-fuel etc. in an environment of high temperature. <P>SOLUTION: The polyacetal resin composition having excellent heat resistance and solvent resistance is obtained by adding 0.1-3.0 pts.wt. tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (B), 0.1-3.0 pts.wt. triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] (C), and a 0.1-3.0 pts.wt. fatty acid calcium salt (D) to a 100 pts.wt. polyacetal resin (A). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polyacetal resin composition having more excellent characteristics in terms of heat resistance, solvent resistance, acid resistance and the like.

  Polyacetal resin has excellent mechanical properties, heat resistance, chemical resistance, electrical properties, etc., and is easy to mold, so it can be used as an engineering plastic for automotive parts, electrical / electronic parts, various machines, building materials, functional miscellaneous goods. This material is widely used in various fields. As one of the fields of use of such polyacetal resin, in the field of automobile parts, it is represented by components that are in direct contact with fuel oil, such as fuel pump modules, using its excellent chemical resistance, particularly fuel resistance. It is also used for large parts such as fuel transfer units.

  On the other hand, in recent years, there is a movement to disseminate so-called biofuels derived from biological resources as a fuel for automobiles, as a measure against global warming due to carbon dioxide emissions, and as a measure against rising oil prices. . However, since biodiesel fuel is produced from various plants and the like, it contains a large amount of impurities such as organic acids, and is more likely to generate acidic substances due to deterioration than conventional diesel fuel (light oil). Therefore, it is required to use a material that has excellent acid resistance as well as fuel resistance for parts that come into direct contact with such a fuel.

  Furthermore, as exhaust gas regulations from diesel vehicles become stricter, it is necessary to increase fuel injection pressure in order to increase combustion efficiency and reduce harmful substances in exhaust gas. Due to the rise, there is an increasing demand for heat resistance of parts used, solvent resistance and acid resistance at high temperatures.

  In response to such demands, Japanese Patent Application Laid-Open No. 2009-132768 (Patent Document 1) discloses a molded article made of a composition in which an antioxidant and a fatty acid metal salt are blended with a polyacetal resin, and shows excellent acid resistance. Has been.

JP2009-132768A

  The molded article made of the composition disclosed in Patent Document 1 exhibits an acid resistance improving effect, but in recent years there has been a demand for higher sophistication, that is, higher heat resistance and solvent resistance in a higher temperature environment. In some cases, it may not be possible to meet the demand for acid resistance.

  The present invention solves the above-mentioned problems, has high heat resistance, solvent resistance, acid resistance, etc., and is particularly used in contact with biofuels etc. in a high temperature environment and requires high durability. It is an object of the present invention to provide a polyacetal resin composition suitable for use and the like, and a molded article comprising the composition.

  As a result of intensive studies to solve the above problems, the present inventors have used a polyacetal resin composition in which a very limited hindered phenol-based compound is used as an antioxidant and a specific additive is added. And the present invention has been achieved.

That is, the present invention
(A) For 100 parts by weight of polyacetal resin,
(B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane 0.1-3.0 parts by weight,
(C) Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] 0.1 to 3.0 parts by weight and (D) fatty acid calcium salt 0.1 to 3.0 parts by weight were added. The polyacetal resin composition having excellent heat resistance and solvent resistance.

  The polyacetal resin composition of the present invention has very excellent heat resistance, solvent resistance, acid resistance and the like. For this reason, it is suitable for automobile fuel containing an acidic component, in particular, for parts that come into contact with biodiesel fuel or the like in a high temperature environment.

Hereinafter, the present invention will be described in detail. The (A) polyacetal resin used in the present invention is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, and is substantially composed of only a repeating unit of an oxymethylene group. And a polyacetal copolymer containing a small amount of other structural units in addition to the oxymethylene group. Any of these can be used, but from the viewpoints of heat resistance, solvent resistance, and acid resistance, which are the objects of the present invention, it is preferable to use a polyacetal copolymer as a base resin. The polyacetal copolymer is preferably a polyacetal copolymer obtained by copolymerizing a comonomer component in an amount of 0.5 to 30% by weight, particularly preferably a copolymer obtained by copolymerizing a comonomer component in an amount of 0.5 to 10% by weight. The polyacetal copolymer obtained by copolymerizing comonomer components has excellent solvent resistance and acid resistance, and excellent thermal stability, and is excellent even when used in contact with a fuel containing acidic components in a high temperature environment. Retains mechanical properties. Moreover, the polyacetal copolymer may have not only a molecule having a linear structure but also a branched structure or a crosslinked structure.

  In producing such a polyacetal copolymer, a cyclic oligomer of formaldehyde represented by trioxane is used as a main monomer. As the comonomer component, a compound selected from cyclic ethers having at least one carbon-carbon bond and cyclic formals is used. Examples of such a comonomer include ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, propylene oxide, and the like.

  In the polyacetal resin (A), particularly the polyacetal copolymer, there is no particular limitation on the degree of polymerization, and the degree of polymerization can be adjusted according to the purpose of use and molding means. The melt index (MI) measured at a temperature of 190 ° C and a load of 2.16 kg is 1 to 100 g / 10 min from the viewpoint of compatibility between various properties such as heat resistance, solvent resistance, and acid resistance, which are intended for It is preferable that it is 5-30 g / 10min.

  The smaller the melt index of the polyacetal resin (A), the lower the fluidity of the resin during molding, which increases the residual stress generated in the molded product during molding, leaving the molded product in a high-temperature acidic solvent atmosphere. At this time, cracks due to solvent cracks are likely to occur. On the other hand, the higher the melt index, the smaller the molecular weight of the polyacetal resin. When the molded product is exposed to a high temperature acidic solvent atmosphere and is attacked by acid, the mechanical properties deteriorate in a short time. The fall of becomes large.

  The present invention relates to (B) tetrakis [methylene-3- (3,5-di-t-butyl-) selected from the hindered phenol antioxidants to the polyacetal resin (A). 4-hydroxyphenyl) propionate] methane and (C) triethyleneglycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] I will.

  It is publicly known to add various hindered phenolic antioxidants in a broad sense to the polyacetal resin to impart an antioxidant function. From the viewpoint of antioxidants, any of the various hindered phenolic antioxidants can be used. Although there are many known documents showing that two or more kinds may be blended, specific two kinds selected from hindered phenolic antioxidants as in the present invention are used in combination with a polyacetal resin. As a result, it was surprising and unexpected that the heat resistance, solvent resistance (fuel resistance), acid resistance, and the like were significantly improved from the description of known documents.

  In the present invention, (B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and (C) triethylene glycol-bis [3- (3-t-butyl -5-Methyl-4-hydroxyphenyl) propionate] is 0.1 to 3.0 parts by weight with respect to 100 parts by weight of (A) polyacetal resin. Further, the sum of the addition amounts (component (B) + component (C)) is preferably 0.5 to 3.0 parts by weight with respect to 100 parts by weight of (A) polyacetal resin. If the blending amount of component (B) and / or component (C) is small, not only the antioxidant properties that are the original function become insufficient, but also the heat resistance and solvent resistance (resistance to resistance) that are the objects of the present invention. Fuel properties), acid resistance and the like are also inferior. When the blending amount of component (B) and / or component (C) is excessive, undesirable effects occur on the mechanical properties and moldability of the resin composition.

  In the polyacetal resin composition of the present invention, (D) fatty acid calcium salt is blended, whereby the acid resistance is drastically improved. (D) The fatty acid constituting the fatty acid calcium salt may be a saturated fatty acid or an unsaturated fatty acid. Examples of such fatty acids include monovalent or divalent fatty acids having 10 or more carbon atoms, such as monovalent saturated fatty acids having 10 or more carbon atoms [capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, stearic acid. C10-34 saturated fatty acids (preferably C10-30 saturated fatty acids) such as arachidic acid, behenic acid and montanic acid], monovalent unsaturated fatty acids having 10 or more carbon atoms [oleic acid, linoleic acid, linolenic acid, C10-34 unsaturated fatty acids such as arachidonic acid and erucic acid (preferably C10-30 unsaturated fatty acids)], divalent fatty acids having 10 or more carbon atoms (dibasic fatty acids) [sebacic acid, dodecanoic acid, tetradecanoic acid , Divalent C10-30 saturated fatty acids (preferably divalent C10-20 saturated fatty acids) such as tapsia acid, divalent C10-30 unsaturated fatty acids (preferably divalent C10-30 saturated fatty acids) such as decenedioic acid and dodecenedioic acid C10-20 not Sum fatty acids), etc.] can be exemplified. In addition, the above fatty acids are partially substituted with a substituent such as a hydroxyl group and a fatty acid having one or more hydroxyl groups in the molecule (eg, hydroxy such as 12-hydroxystearic acid). Saturated C10-26 fatty acids and the like).

  In the polyacetal resin composition of the present invention, particularly preferable (D) fatty acid calcium salts are calcium stearate, calcium 12-hydroxystearate, and calcium behenate.

  In this invention, the addition amount of (D) fatty acid calcium salt is 0.1-3.0 weight part with respect to 100 weight part of (A) polyacetal resin. The blending of (D) fatty acid calcium salt greatly contributes to the improvement of acid resistance. (D) If the added amount of the fatty acid calcium salt is less than 0.1 parts by weight, the desired acid resistance cannot be obtained, and if it exceeds 3.0 parts by weight, the mechanical properties and the like are impaired.

  The polyacetal resin composition of the present invention preferably further contains one or both of (E) a formaldehyde-reactive nitrogen-containing compound and (F) a lubricant.

  Examples of (E) formaldehyde-reactive nitrogen-containing compounds that can be used in the present invention include melamine and its derivatives (including guanamine and its derivatives), melamine formaldehyde resins, hydrazide compounds, polyamides and polyacrylamides.

  First, melamine and its derivatives include melamine (2,4,6-triamino-sym-triazine), melem, melam, melon, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N Diallyl melamine, N, N ", N" -trimethylol melamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), 2,4-diamino-6-methyl-sym-triazine, 2,4 -Diamino-6-butyl-sym-triazine, 2,4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl- sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, 2,4-dioxy-6-mercapto-sym-triazine 2,4-Dioxy-6-amino-sym-triazine (Amelide), 2-oxy-4,6-Diamino-sym-Triazine (Ameline), N, N, N ′, N′-Tetracyanoethylbenzoguanamine, etc. It is done.

  Examples of the melamine formaldehyde resin include water-insoluble melamine-formaldehyde polycondensate produced from melamine and formaldehyde in a molar ratio of 1: 0.8 to 1: 10.0.

  Examples of the hydrazide compound include adipic acid hydrazide and sebacic acid hydrazide.

  Polyamides such as nylon 12, nylon 6,10, nylon 6,66,610, single or copolymerized polyamides, substituted polyamides having methylol groups, nylon salts, synthesized from caprolactam, or synthesized from caprolactone, caprolactam And polyester amides to be used.

  Examples of polyacrylamide include one or more of acrylamide homopolymers, copolymers thereof, and cross-linked products.

  As the (E) formaldehyde-reactive nitrogen-containing compound that is preferably used in the present invention, among the above compounds, melamine, melamine derivatives, and melamine formaldehyde resins are particularly preferable.

  In the present invention, when the (E) formaldehyde-reactive nitrogen-containing compound is blended, the blending amount is preferably 0.001 to 3.0 parts by weight with respect to 100 parts by weight of the (A) polyacetal resin.

  Examples of the (F) lubricant that can be used in the present invention include fatty acid esters and fatty acid amides.

  Examples of fatty acid esters include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid, and behenic acid, and monovalent aliphatics such as palmityl alcohol, stearyl alcohol, and behenyl alcohol. Alcohol, ester compounds with polyhydric aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, sorbitan, fatty acid and polybasic organic acid and monohydric aliphatic alcohol or polyhydric aliphatic alcohol compound ester compound, etc. Can be mentioned. Specific examples of such fatty acid ester lubricants include, for example, cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerol monocaprylate, glycerol monocaprate, glycerol monolaurate, glycerol monopalmitate, Glycerol dipalmitate, glycerol monostearate, glycerol distearate, glycerol tristearate, glycerol monooleate, glycerol dioleate, glycerol trioleate, glycerol monolinoleate, glycerol monobehenate, glycerol mono12-hydroxystearate Rate, glycerol di12-hydroxystearate, glycerol tri-12-hydroxystearate, glycerol diacetomonostearate, glycerol quencher Fatty acid esters, pentaerythritol adipate stearate, montanic acid partially saponified esters, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate, and the like.

  Specific examples of fatty acid amide lubricants include, for example, saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide; oleic acid amide, erucic acid amide, ricinoleic acid amide Unsaturated fatty acid amides such as N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, etc. Substituted amide; methylol amide such as methylol stearic acid amide and methylol behenic acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide Allylamide), ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N, N′-di Saturated fatty acid bisamides such as stearyl adipic acid amide and N, N′-distearyl sebacic acid amide; ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′— Examples thereof include unsaturated fatty acid bisamides such as dioleyl sebacic acid amide; aromatic bisamides such as m-xylylene bisstearic acid amide and N, N′-distearylisophthalic acid amide.

  In the present invention, when the (F) lubricant is blended, the blending amount is preferably 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the (A) polyacetal resin. When the blending amount of the (F) lubricant is small, the original release property is insufficient, and when it is excessive, the biting property at the time of molding is inferior and it is difficult to obtain a good molded product.

  In the polyacetal resin composition of the present invention, various known stabilizers and additives can be further blended within a range that does not significantly impair the object and effect of the present invention. For example, anti-glare stabilizers, impact resistance improvers, gloss control agents, slidability improvers, mold release agents, antistatic agents, nucleating agents, colorants, antioxidants other than those mentioned above, heat stabilizers, lubricants Etc. In addition, various inorganic fillers in the form of fibers, plates, and granules, and blends of different polymers can be used.

  There is no restriction | limiting in particular in the preparation method of the composition of this invention, It can prepare easily by the well-known equipment and method conventionally used as a preparation method of a thermoplastic resin composition.

  The molded product of the present invention is molded by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, etc., using the polyacetal resin composition having the above-described configuration. Can be obtained.

  Although there are no particular restrictions on its use, it makes contact with fuels for automobiles, especially diesel fuel, taking advantage of the characteristics of the polyacetal resin composition of the present invention such as heat resistance, solvent resistance (fuel resistance), and acid resistance. The present invention can be particularly preferably applied to parts to be made.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Examples 1-4 and Comparative Examples 1-24
(A) Polyacetal resin was added to (B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, (C) triethylene glycol-bis [3- (3- t-butyl-5-methyl-4-hydroxyphenyl) propionate], (D) fatty acid calcium salt, (E) formaldehyde-reactive nitrogen-containing compound, and (F) lubricants in the proportions (weight) Part) was added and mixed, and melt-kneaded with a twin-screw extruder to prepare a pellet-shaped composition. Details of the ingredients are as described below.

  Next, an ISO tensile test piece TYPE 1A was produced by injection molding using this pellet. The molded test piece was immersed in JIS No. 2 light oil, treated at 110 ° C. for 300 hours, then taken out from the light oil and measured for tensile properties. Since the decrease in tensile elongation was most sensitive when the light oil immersion treatment was performed, the light oil resistance was evaluated based on the tensile elongation retention rate. The results are shown in Tables 1 and 2.

  For comparison, a composition not containing any of (B), (C) and (D), (B) or (C) was increased alone instead of using (B) and (C) together Prepare a composition using another hindered phenolic antioxidant in place of (B), and a composition using another hindered phenolic antioxidant in place of (C). And evaluated. The results are also shown in Table 1.

  From Table 1 and Table 2, among the hindered phenolic antioxidants, (B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and (C) By selecting triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] and using it together, and (D) compounding with fatty acid calcium salt The effect is obvious.

As a hindered phenolic antioxidant, (B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane or (C) triethylene glycol-bis [3- ( 3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] alone, and increasing this amount does not provide a sufficient effect, and these are also used as other hindered phenolic antioxidants. Even if used in combination, sufficient effects cannot be obtained.
[Ingredients]
(A) Polyacetal resin A polyacetal copolymer obtained by copolymerizing 96.7% by weight of trioxane and 3.3% by weight of 1,3-dioxolane. A material with a melt index (measured at 190 ° C and a load of 2160 g) of 8.9 g / 10 min is used.
(B) Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (C) Triethyleneglycol-bis [3- (3-t-butyl-5-methyl- 4-hydroxyphenyl) propionate]
(D) Fatty acid calcium salt Uses calcium stearate (E) Formaldehyde-reactive nitrogen-containing compound Uses melamine (F) Uses lubricant Glycerol monostearate (X) Others (Hinder used instead of (B) and (C) Dophenol antioxidants)
X-1: Hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 259, manufactured by Ciba Japan Co., Ltd.)
X-2: Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076, manufactured by Ciba Japan)
X-3: 2,2'-methylenebis (6-tert-butyl-4-methylphenol) (Irganox 2246, manufactured by Ciba Japan Co., Ltd.)

Claims (5)

(A) For 100 parts by weight of polyacetal resin,
(B) tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane 0.1-3.0 parts by weight,
(C) Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] 0.1 to 3.0 parts by weight and (D) fatty acid calcium salt 0.1 to 3.0 parts by weight were added. A polyacetal resin composition having excellent heat resistance and solvent resistance.   The polyacetal resin composition according to claim 1, further comprising (E) 0.001 to 3.0 parts by weight of a formaldehyde-reactive nitrogen-containing compound (100 parts by weight of component (A)).   The polyacetal resin composition according to claim 1 or 2, further comprising 0.1 to 3.0 parts by weight of (F) a lubricant (100 parts by weight of component (A)).   (B) Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and (C) Triethylene glycol-bis [3- (3-t-butyl-5-methyl The polyacetal resin composition according to any one of claims 1 to 3, wherein the sum of the addition amount of 4-hydroxyphenyl) propionate] is 0.5 to 3.0 parts by weight.   The molded article which consists of a polyacetal resin composition of any one of Claims 1-4.