JP5612262B2 - Polyacetal resin composition - Google Patents

Description

  The present invention provides a polyacetal resin and a powdery glass-based inorganic while maintaining excellent properties such as high rigidity, low warpage, and low deformation of a resin composition obtained by blending a powdered glass-based inorganic filler with a polyacetal resin. The present invention relates to a polyacetal resin composition in which mechanical strength is improved by improving affinity with a filler, and characteristics such as immersion in hot water and fracture life (creep characteristics) under a constant stress are greatly improved.

  Polyacetal resin has excellent properties in mechanical, thermal properties, electrical properties, slidability, moldability, dimensional stability of molded products, etc., as structural materials and mechanical parts, electrical equipment, automotive parts, precision Widely used for machine parts.

  In addition, in order to improve the mechanical properties of polyacetal resin, such as strength and rigidity, it is known to add reinforcing materials such as glass-based inorganic fillers, with the aim of improving rigidity and reducing warpage and deformation. In this case, it is known to blend a powdery glass filler such as a glass bead or a glass frame as a glass-based inorganic filler.

  However, polyacetal resin has poor activity, and glass-based inorganic fillers also have poor activity. Therefore, simply blending glass-based inorganic filler with polyacetal resin and melt-kneading will result in insufficient adhesion between the two. In many cases, the mechanical properties cannot be improved as much as possible.

  Therefore, various methods have been proposed to improve the mechanical properties by improving the adhesion between the polyacetal resin and the glass-based inorganic filler. When the glass-based inorganic filler is a glass fiber, for example, polyacetal Adding glass fiber and phenoxy resin to the resin (Patent Document 1), adding glass fiber, peroxide and silane coupling agent to the polyacetal resin (Patent Document 2), sizing the polyacetal resin with polyurethane emulsion It is known that glass fibers are blended, and that a silane coupling agent is contained in a polyurethane emulsion (Patent Document 3). Further, a glass fiber and glass surface-treated with a silane coupling agent, preferably a polyacetal resin. It is known to blend with flakes (Patent Document 4) There.

Moreover, as an improvement method in the case of compounding a glass-based inorganic filler in a broad sense including powdered glass fillers such as glass beads and glass flakes, for example, a glass-based inorganic filler and a boric acid compound are added to a polyacetal resin. (Patent Document 5), adding a glass-based inorganic filler and a hydroxycarboxylic acid compound to a polyacetal resin (Patent Document 6), and a composition obtained by blending a glass-based inorganic filler with a polyacetal resin component, the polyacetal The resin component is composed of a polyacetal resin having a linear molecular structure and a polyacetal resin having a branched or crosslinked structure (Patent Document 7). The polyacetal resin has a glass-based filler, a boric acid compound, and a nitrogen-containing functional group. Compounding a triazine derivative (Patent Document 8), a polymer having a linear molecular structure A polyacetal resin composition comprising a polyacetal resin having branched or crosslinked structure and tar resin, blending the glass inorganic filler and a boric acid compound (Patent Document 9) are known.
JP 49-98458 A JP 60-219252 A JP-A-61-236851 JP-A-62-91551 Japanese Patent Laid-Open No. 9-151298 JP 2002-371168 A JP 2005-29714 A JP 2006-70196 A JP 2008-44995 A

  According to these conventionally known methods, they function to enhance the chemical activity of the glass-based inorganic filler and, although there are differences in degree, both contribute to the improvement of characteristics. However, it is difficult to sufficiently improve the adhesion with a chemically inert polyacetal resin by these methods alone, and desired characteristics may not be achieved. In particular, when powdered glass-based inorganic fillers such as glass beads and glass flakes are blended as glass-based inorganic fillers, the mechanical strength is maintained while maintaining the characteristics such as rigidity, low warpage, and low deformation. Or it is very difficult to improve. Further, in recent years, improvement of characteristics under specific environments such as fracture life (creep characteristics) under hot water immersion or constant stress may be required. Therefore, it is difficult to meet such a demand.

  An object of the present invention is to solve such problems and to provide a polyacetal resin composition capable of meeting higher-level properties required in recent years with the expansion of the field of use of polyacetal resins.

  As a result of intensive research to solve such problems, the present inventor has solved these problems by selectively combining a specific component together with a granular glass-based inorganic filler in a polyacetal resin. The present inventors have found that a polyacetal resin composition having excellent mechanical strength and drastically improved long-term life of hot water resistance and creep characteristics can be obtained, and the present invention has been completed.

That is, the present invention
(A1) 30 to 95% by weight of a polyacetal resin having a linear molecular structure,
(A2) 0.05 to 10% by weight of polyacetal resin having a branched or crosslinked structure,
(B) 5-50% by weight of powdered glass-based inorganic filler,
(C) Trifunctional isocyanate compound 0.1 to 10% by weight,
(D) 0.05 to 2% by weight of a compound selected from an amine compound (D1) and an organometallic compound (D2) containing a metal selected from Sn, Zn, and Pb, and (E) any additive 0 to 20% by weight
And a polyacetal resin composition having a total amount of 100% by weight.

  The configuration of the present invention will be described below.

First, the polyacetal resin (A1) having a linear molecular structure used in the present invention is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, and is a repeating unit of an oxymethylene group. Typical examples thereof include polyacetal homopolymers composed solely of polyacetal copolymers, and polyacetal copolymers (including block copolymers) having oxymethylene groups as main structural units and small amounts of other structural units that do not form a branched or crosslinked structure. In the present invention, any of these linear acetal resins having a linear molecular structure can be used, and if necessary, two or more types of linear polyacetal resins having different characteristics may be blended and used. However, it is preferable to use a polyacetal copolymer from the viewpoints of moldability, thermal stability, and the like.

Such a polyacetal copolymer is obtained by copolymerizing 99.95 to 80.0% by weight of trioxane (a) and 0.05 to 20.0% by weight of a compound (b) selected from a cyclic ether compound having no substituent and a cyclic formal compound. More preferably, it is obtained by copolymerizing 99.9 to 90.0% by weight of trioxane (a) and 0.1 to 10.0 of compound (b). The melt index (measured at 190 ° C. and a load of 2.16 kg) is preferably 1 to 50 g / 10 min.

  Examples of the comonomer component (the compound (b)) used in the production of the polyacetal copolymer include known ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, propylene oxide, and the like. A cyclic ether compound and a cyclic formal compound are mentioned. Particularly preferred are compounds selected from ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal and diethylene glycol formal, and one or more of them can be used as a comonomer component.

  The preparation method of a polyacetal resin (A1) is not specifically limited, It can prepare by a well-known method.

Next, the polyacetal resin (A2) having a branched or cross-linked structure used in the present invention can be copolymerized with formaldehyde or trioxane in the production of the polyacetal homopolymer or polyacetal copolymer as described above, and can be branched by copolymerization. Alternatively, it can be obtained by further adding a compound capable of forming a crosslinking unit and copolymerizing. For example, when copolymerizing trioxane (a) and a compound (b) selected from a cyclic ether compound having no substituent and a cyclic formal compound, a monofunctional glycidyl compound having a substituent (for example, phenyl glycidyl ether, butyl glycidyl) A polyacetal resin having a branched structure can be obtained by further adding an ether or the like and copolymerizing, and a polyacetal resin having a crosslinked structure can be obtained by adding and copolymerizing a polyfunctional glycidyl ether compound. In the present invention, it is preferable to use a polyacetal resin (A2) having a crosslinked structure. Among them, trioxane (a) 99.89 to 88.0% by weight, monofunctional cyclic ether compound having no substituent and monofunctional cyclic formal Those obtained by copolymerizing 0.1 to 10.0% by weight of the compound (b) selected from the compounds and 0.01 to 2.0% by weight of the polyfunctional glycidyl ether compound (c) are preferred, and trioxane (a) 99.28 to 96.50% by weight is particularly preferred. %, Compound (b) 0.7 to 3.0% by weight and polyfunctional glycidyl ether compound (c) 0.02 to 0.5% by weight. A crosslinked polyacetal resin having a melt index of 0.1 to 10 g / 10 min is preferred.

  As the compound (b), the same compounds as the compound (b) constituting the polyacetal resin (A1) having the above-mentioned linear molecular structure can be used, and in particular, ethylene oxide, 1,3-dioxolane, 1,4-butane. One type or two or more types selected from the group consisting of diol formal and diethylene glycol formal are preferred.

  The polyfunctional glycidyl ether compound (c) is particularly preferably one having 3 to 4 glycidyl ether groups in one molecule, specifically, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether and pentaerythritol tetra A glycidyl ether is mentioned. The method for preparing the polyacetal resin (A2) having a branched or crosslinked structure is not particularly limited, and it can be prepared by a known method in the same manner as the preparation of the polyacetal resin (A1).

  In the present invention, the blending amount of the polyacetal resin (A2) having such a branched or cross-linked structure is 0.05 to 10% by weight with respect to 30 to 95% by weight of the polyacetal resin (A1). If the blending amount of the polyacetal resin (A2) having a branched or crosslinked structure is small, the mechanical properties are not sufficiently improved, and the molding is performed even when the blending amount of the polyacetal resin (A2) having a branched or crosslinked structure is excessive. Workability and the like are inferior, resulting in insufficient mechanical properties.

  Next, as the (B) granular glass-based inorganic filler used in the present invention, glass beads and glass flakes are particularly desirable from the viewpoint of improving the strength of the resulting resin composition and reducing anisotropy. Even a milled fiber is preferably used if L / D is less than 50.

  Further, the glass-based inorganic filler to be used is preferably one that has been surface-treated with an aminosilane compound or an epoxysilane compound. Further, those that are aggregated with a polyurethane-based resin or oligomer are preferred, and handling becomes easier.

  The amount of the powdery glass-based inorganic filler (B) added is 5 to 50% by weight, preferably 5 to 25% by weight. When the addition amount is less than 5% by weight, the effect of reinforcing the filler hardly appears. On the other hand, if it exceeds 50% by weight, the extrusion processability is greatly lowered, and the composition cannot be produced in practice, which is not preferable.

  The (C) trifunctional isocyanate compound used in the present invention is a compound containing three isocyanate groups in one molecule. As the trifunctional isocyanate compound, a trimer of a diisocyanate compound is preferable. For example, 4,4′-methylenebisphenyl isocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6- A trimer of tolylene diisocyanate can be exemplified. These compounds can be used alone or in admixture of two or more.

  The compounding quantity of a trifunctional isocyanate compound (C) is 0.1 to 10 weight%, Preferably it is 1 to 3 weight%. If the blending amount of the trifunctional isocyanate compound is less than 0.1% by weight, the effect of improving the adhesion between the polyacetal resin and the granular glass inorganic filler is insufficient, and if it exceeds 10% by weight, the viscosity of the polyacetal resin is increased. The extrusion processability is very low, which is not preferable.

  Further, in the present invention, the amine compound (D1) and / or the organometallic compound (D2) containing a metal selected from Sn, Zn, and Pb to be blended as the component (D) is composed of polyacetal resin and granular glassy inorganic. It is considered that when the adhesion to the filler is improved by the trifunctional isocyanate compound, it acts as an auxiliary.

  The amine compound (D1) and the organometallic compound (D2) are preferably those which do not give adverse effects such as discoloration and decomposition to the polyacetal resin. From this viewpoint, the amine compound (D1) is an amino group-containing triazine. System compounds or derivatives thereof are preferred, and specific examples include melamine, benzoguanamine, and melamine resin. The organometallic compound (D2) is preferably a metal fatty acid salt selected from Sn, Zn, and Pb, and examples thereof include zinc stearate and di-n-butyltin dilaurate.

  The amount of component (D) needs to be in the range of 0.05 to 2% by weight. If it is less than 0.05% by weight, the combined effect does not appear, and if it exceeds 2% by weight, discoloration of the polyacetal resin and deterioration of the resin properties occur, which is not preferable.

  In the resin composition of the present invention, 0 to 20% by weight of any additive (E) can be blended. Additives (E) that are preferably blended include hindered antioxidants and stabilizers for improving thermal stability. Furthermore, if necessary, ultraviolet absorbers, lubricants, lubricants, mold release agents, colorants including dyes and pigments, surfactants, various inorganic fillers and reinforcing materials other than the component (B), various heavy metals A coalescence etc. can also be mix | blended.

  The composition of the present invention is easily prepared by a known method generally used as a conventional resin composition preparation method. For example, after mixing each component, kneading and extruding with an extruder to prepare pellets, once preparing pellets with different compositions, mixing a predetermined amount of the pellets and using them for molding. Any of a method for obtaining the above, a method for directly charging one or more of each component into a molding machine, and the like can be used.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
The measurement / evaluation method was as follows.
<Tensile strength and elongation>
A tensile test piece according to ISO 3167 was allowed to stand for 48 hours under conditions of a temperature of 23 ° C. and a humidity of 50%, and the measurement was performed according to ISO 527.
<Heat resistant water>
Using a tensile test piece according to ISO 3167, the specimen was taken out after being immersed in an autoclave containing hot water at a temperature of 120 ° C. for 120 hours, and the tensile strength was measured under the above conditions of <tensile strength and elongation>. The tensile strength retention was calculated with the tensile strength value measured in the above <Tensile strength and elongation> as 100%.
Production Examples 1 to 3 (branched or cross-linked polyacetal resin (A2))
Using a two-axis continuous mixing reactor with a jacket through which the temperature control medium passes and a barrel with two paddles inside the barrel, each of the two axes is rotated at 150 rpm. While adding trioxane (a), a compound (b) selected from a cyclic ether compound and a cyclic formal compound, and a polyfunctional glycidyl ether compound (c) in the proportions shown in Table 1, and continuously adding methylal as a molecular weight regulator. Then, 0.005% by weight of boron trifluoride as a catalyst was continuously added and fed to trioxane to perform bulk polymerization. While rapidly passing the reaction product discharged from the polymerization machine through a crusher, the catalyst was deactivated by adding it to a 60 ° C. aqueous solution containing 0.05% by weight of triethylamine. Furthermore, after separation, washing and drying, a crude polyacetal resin was obtained.

  Subsequently, 3 weight% of triethylamine 5 weight% aqueous solution and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] are added to 100 weight parts of the crude polyacetal resin. 0.3 wt% was added, and melted and kneaded at 210 ° C with a twin screw extruder to remove unstable parts to obtain a pellet-like polyacetal resin, which was used for the preparation of a polyacetal resin composition.

Table 1 shows the composition and melt index of these polyacetal resins. The abbreviations in the table are as follows.
(B) Component
DO: 1,3-dioxolane
BF: 1,4-butanediol formal (c) component
TMPTGE: Trimethylolpropane triglycidyl ether

Examples 1-11, Comparative Examples 1-5
Linear polyacetal resin (A1) (trade name Duracon (registered trademark) M90, manufactured by Polyplastics Co., Ltd.), branched / crosslinked polyacetal resin (A2-1 to A2-3) prepared above, and Various powdered glass fillers (B1, B2), isocyanate compounds (C1), amine compounds (D1) or organometallic compounds (D2) shown in Table 2 are blended in the proportions shown in Table 2, and the cylinder temperature is 200 ° C. A pellet-shaped composition was prepared by melt-kneading with an extruder. Next, a test piece was molded from the pellet-shaped composition using an injection molding machine, and physical properties were evaluated by the evaluation method described above. The results are shown in Table 2.

  On the other hand, for comparison, a pellet-like composition is similarly applied to a case where the components (A2), (B1) and (D) are not added, and an isocyanate compound (C2) which is not a trimer is used. Preparation and physical property evaluation were performed. The results are shown in Table 3.

The compositions of Examples 1 to 11 according to the present invention have high initial tensile strength, excellent tensile strength retention after hot water immersion treatment, which is an accelerated test, and high strength during hot water immersion treatment. It can be seen that was maintained. On the other hand, in the compositions of Comparative Examples 1 and 3, the initial tensile strength itself is low, and in the compositions of Comparative Examples 2, 4, and 5, the tensile strength retention ratio and tensile strength (absolute value) after the hot water immersion treatment. ) Is inferior, and both are insufficient.
<Used glass-based inorganic filler>
B1: Glass beads surface-treated with γ-aminopropyltriethoxysilane B2: Glass beads surface-treated with γ-glycidoxypropyltriethoxysilane <Used isocyanate compound>
C1: IPDI-T: isophorone diisocyanate trimer C2: MDI: 4,4′-diphenylmethane diisocyanate (comparative example)
<Amines or organometallic compounds used>
D1: Melamine
D2: Zinc stearate

Claims (9)

(A1) 57.9-87.9 % by weight of polyacetal resin having a linear molecular structure,
(A2) 1 to 5 % by weight of polyacetal resin having a branched or crosslinked structure,
(B) 10-40 % by weight of powdered glass-based inorganic filler,
(C) 1 to 3 % by weight of a trifunctional isocyanate compound,
(D) 0.1 to 0.3 % by weight of a compound selected from an amine compound (D1) and an organometallic compound (D2) containing a metal selected from Sn, Zn, and Pb, and (E) any additive 0 to 20% by weight
A polyacetal resin composition comprising 100% by weight in total. The polyacetal resin (A2) having a branched or crosslinked structure is composed of 99.89 to 88.0% by weight of trioxane (a), 0.1 to 10.0% by weight of a compound (b) selected from a cyclic ether compound having no substituent and a cyclic formal compound. The polyacetal resin composition according to claim 1, which is a crosslinked polyacetal copolymer obtained by copolymerizing 0.01 to 2.0% by weight of the functional glycidyl ether compound (c) and having a melt index of 0.1 to 10 g / 10 min.   The polyacetal resin composition according to claim 2, wherein the polyfunctional glycidyl ether compound (c) is selected from trifunctional or tetrafunctional glycidyl ether compounds.   The polyacetal resin composition according to any one of claims 1 to 3, wherein the powdered glass-based inorganic filler (B) is glass beads or glass flakes.   The polyacetal resin composition according to any one of claims 1 to 4, wherein the particulate glass-based inorganic filler (B) is surface-treated with an aminosilane compound or an epoxysilane compound.   The polyacetal resin composition according to any one of claims 1 to 5, wherein the trifunctional isocyanate compound (C) is a trimer of a diisocyanate compound.   The diisocyanate compound is selected from 4,4'-methylenebisphenyl isocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. The polyacetal resin composition described in 1.   The polyacetal resin composition according to any one of claims 1 to 7, wherein the amine compound (D1) is an amino group-containing triazine compound or a derivative thereof.   The polyacetal resin composition according to any one of claims 1 to 8, wherein the organometallic compound (D2) is a fatty acid salt of a metal selected from Sn, Zn, and Pb.