JPH11100486A - Polyoxymethylene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in heat stability and moldability and useful for the mechanical parts of automobiles, etc., electric and electronic apparatuses, office machines such as a computer, building pipes, general merchandise, etc., by blending a polyoxymethylene resin with an antioxidant having a specific structure. SOLUTION: The objective composition is obtained by blending (A) 100 pts.wt. of a polyoxymethylene resin with (B) 0.001 to 3 pts.wt. of a compound shown by formula I (R1 and R2 are each an alkyl) and further pref. 0.001 to 3 pts.wt. of a compound shown by formula II (C) and/or a compound shown by formula III (D), and by adding thereto 0.01 to 10 pts.wt. of formaldehyde-trapping agent (e.g. melamine, benzoguanamine, cyanoguanidine). Preferably, the component A serves as a catalyst-deacrivating agent obtained by adding (E) 0.01 to 3 pts.wt. of a hindered amine compound to 100 pts.wt. of a crude polymer resulted from adding a catalyst for polymerization to trioxane and cyclic ether, etc., as a copolymerizable component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene resin composition having excellent heat stability and molding properties.

[0002]

2. Description of the Related Art Polyoxymethylene resins are known as engineering plastics having a good balance between mechanical strength and impact resistance, and are used in a wide range of fields as electronic equipment and automobile parts. In recent years, heat stability and appearance stability have been required of polyoxymethylene resins. In addition, high molding characteristics have been required to improve mass productivity.

Hitherto, various attempts have been made to add heat stabilizers for the purpose of improving the heat resistance of polyoxymethylene resins.

For example, Japanese Patent Publication No. 7-728 discloses a hindered phenol compound pentaerythrityl-tetrakis [3- (3,5-di-t) as an antioxidant.
-Butyl-4-hydroxyphenylpropionate].

JP-A-6-49321, JP-A-8-49321
Japanese Patent No. 231821 describes addition of a hindered phenolic antioxidant, and in Examples, pentaerythritol tetrakis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate],
Or triethylene glycol-bis [3- (3-t-
Butyl-5-methyl-4-hydroxyphenyl) propionate].

JP-A-7-258517, JP-A-7-258517
JP-A-268180 and JP-A-7-278407 propose the addition of a hindered phenol-based, phosphorus-based, hindered amine-based, or sulfur-based antioxidant.

However, these additives are insufficient in the effect of suppressing discoloration and deterioration of the surface appearance, and are not always sufficient in terms of generation of mold deposits (mold deposit) during molding.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a polyoxymethylene resin composition having excellent heat stability and excellent molding properties.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that a polyoxymethylene resin composition obtained by adding an antioxidant having a specific structure to a polyoxymethylene resin. Has been found to be excellent in heat resistance and molding properties, and have reached the present invention.

That is, the present invention relates to (1) (A) 100 parts by weight of polyoxymethylene resin (B)

Embedded image (R1 and R2 represent alkyl groups.) A polyoxymethylene resin composition comprising 0.001 to 3 parts by weight of a compound represented by the formula (2): 100 parts by weight of a polyoxymethylene resin (A) For the part, (C)

Embedded image And / or (D)

Embedded image (R1 and R2 represent alkyl groups). The polyoxymethylene resin composition according to the above (1), further comprising 0.001 to 3 parts by weight of a compound represented by the formula (1):
For 100 parts by weight of the polyoxymethylene resin (A),
The above-mentioned (1), further comprising 0.01 to 10 parts by weight of one or more compounds selected from melamine, benzoguanamine and cyanoguanidine as a formaldehyde scavenger.
Or the polyoxymethylene resin composition according to (2).

(4) The polyoxymethylene resin (A) is
Triolane and at least one cyclic ether or cyclic formal as a copolymerization component, and a coordination compound of boron trifluoride, boron trifluoride hydrate, and an organic compound containing an oxygen atom or a sulfur atom with boron trifluoride At least one selected polymerization catalyst is added, and the hindered amine compound (E) is added in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the crude polymer obtained by polymerization, and the catalyst is deactivated. A polyoxymethylene resin composition according to any one of the above (1) to (3).

(5) The crude polymer obtained by polymerizing trioxane and at least one cyclic ether or cyclic formal as a copolymerization component

Embedded image (R1 and R2 represent alkyl groups), and then the unstable terminal is removed to produce the polyoxymethylene resin composition according to the above (1). The method for producing a polyoxymethylene resin composition described above.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(A) The polyoxymethylene resin may be either an oxymethylene homopolymer or an oxymethylene copolymer having oxymethylene units, but is preferably an oxymethylene copolymer.

The oxymethylene copolymer is mainly an oxymethylene copolymer having preferably at least 90 mol% of oxymethylene units and at least one oxyalkylene unit having 2 to 8 carbon atoms as a copolymer component. No.

The oxymethylene copolymer can be produced by a known method. For example, substantially anhydrous trioxane and at least one cyclic ether or cyclic formal as a copolymerization component, and a polymerization catalyst (for example, trifluoride) Boron, boron trifluoride hydrate and at least one compound having a catalytic ability such as a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom), and then polymerized. After the catalyst contained in the obtained crude polymer is deactivated by a catalyst deactivator or removed by washing, it can be produced by decomposing and removing unstable terminals. In particular, a method of introducing a preliminary mixture of trioxane and a copolymer component / catalyst into a self-cleaning type stirrer and performing bulk polymerization is preferable.

The compound (B) used in the present invention is

Embedded image Wherein R1 and R2 are alkyl groups represented by CnH2n + 1, preferably 1 ≦ n ≦ 10, and particularly preferably n = 1 in the present invention. There is no particular limitation on the timing of addition, but it is preferable to add it before the reaction for decomposing and removing the unstable terminal. The addition amount is from 0.001 to 3 parts by weight, preferably from 0.005 to 1.5 parts by weight, particularly preferably from 0.05 to 1.5 parts by weight, per 100 parts by weight of the polyoxymethylene resin.
It is preferably from 1 to 1 part by weight.

In the present invention,

Embedded image And / or a compound (C) represented by

Embedded image It is possible to mix the compound (D) represented by

In the above formula for the compound (D), R3 is CnH
An alkyl group represented by 2n + 1, preferably 11 ≦ n ≦ 30, and particularly preferably n = 18 in the present invention.

Compound (C) and / or compound (D)
There is no particular limitation on the method and timing of adding, and they may be added separately or may be added in advance by mixing. As for the timing of the addition, it is preferable to add it before the reaction for decomposing and removing the unstable terminal. The amount of the compound (C) and / or compound (D) added is 0.001 to 3 parts by weight based on 100 parts by weight of the pooxymethylene resin.
It is preferably 0.005 to 1.5 parts by weight, particularly preferably 0.01 to 1 part by weight. When two or more compounds corresponding to compound (C) and / or (D) are used in combination, the total amount is used.

As the catalyst deactivator, hindered amine,
Examples thereof include amine compounds such as triethylamine and phosphorus compounds such as triphenylphosphine, and hindered amines are particularly preferable.

These catalyst deactivators use, as a polymerization catalyst, boron trifluoride, boron trifluoride hydrate or a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. It is effective when used.

Preferred hindered amine compounds (E) as catalyst deactivators include bis (1,2,2,6,6).
-Pentamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6 , 6-Tetramethylpiperidyl polycondensate, N-N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4 -Piperidyl) amino] -6 chloro 1,3,5-triazine condensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] {2,2,6,6-tetramethyl-4-piperidyl) imino {hexamethylene} (2,2,6,6-tetramethyl-4-piperidyl) imino} and the like. Or 2 Used in more than species. The range of the amount of hindered amine to be added is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the crude polymer obtained by the polymerization reaction.

As a method of removing the unstable terminal, a method of adding a hydroxide of a metal such as calcium, magnesium or strontium or an organic acid salt such as a stearate and heating the mixture can be mentioned. Examples of the metal hydroxide or organic acid salt include metal hydroxides such as calcium hydroxide and magnesium hydroxide; calcium stearate;
Examples include metal stearate such as calcium 2-hydroxystearate, magnesium stearate, and strontium stearate. As a heating condition, it is preferable to heat at 150 to 260 ° C. Further, the heating time is preferably from 3 minutes to 15 minutes.

In the present invention, it is preferable to add a formaldehyde scavenger after removing the unstable terminal as described above.

As the formaldehyde additive, triazine compounds such as benzoguanamine and melamine, and amidine compounds such as cyanoguanidine are preferable. These are used alone or in combination of two or more.

The amount of the formaldehyde scavenger used in the present invention is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 2 parts by weight, based on 100 parts by weight of the polyoxymethylene resin.

As a method for producing the polyoxymethylene resin composition of the present invention, generally known methods can be employed. For example, a method of adding an additive in the polymerization or stabilization step of the polyoxymethylene resin, mixing the polyoxymethylene resin and the additive in pellets, powders, or granules, and performing melt processing as it is, After completion of the reaction, a catalyst deactivator is added to deactivate the catalyst, or the polymer from which the catalyst has been removed by washing, and before the reaction for removing the unstable terminal is performed, the compounds (B) to (D) are added. Is preferably added.

As a mixing method, a Banbury mixer,
A method of melt-mixing with a roll, an extruder or the like can be used. In particular, using a single or twin screw extruder,
A method of melt-mixing at a temperature of ~ 260 ° C is preferred.

Further, a light stabilizer and an ultraviolet absorber other than those described above may be added to the resin composition of the present invention as long as the effects of the present invention are not impaired. Further, additives and fillers usually used in polyoxymethylene resin, for example, fillers such as calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, mica powder, glass beads, carbon fiber, Reinforcing agent such as glass fiber, ceramic fiber, aramid fiber, potassium titanate fiber, coloring agent (pigment, dye), nucleating agent, plasticizer, release agent such as ethylene bis stearamide, polyethylene wax, carbon black , A conductive agent, a pressure-sensitive adhesive, a polyhydric alcohol, a fatty acid ester, a lubricant such as a metal soap, a hydrolysis resistance improving agent, an adhesion aid and the like.

The polyoxymethylene resin composition obtained by the present invention can be used for molded parts in all fields requiring heat resistance, for example, equipment parts such as automobiles, electric / electronic equipment,
It can be suitably used for office equipment such as computers, other applications such as construction plumbing and miscellaneous goods.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

[0032]

The present invention will be described below with reference to examples. All percentages and parts in the examples are on a weight basis.

The mechanical properties, color tone, surface appearance, heat aging resistance and low mold depositability of the molded articles shown in the examples and comparative examples were measured as follows.

Molding: Using an injection molding machine having a mold clamping pressure of 60 tons, cylinder temperature 190 ° C., mold temperature 80 ° C.
An ASTM No. 1 dumbbell specimen was injection molded with a molding cycle set to 20 seconds.

Mechanical properties: Tensile strength was measured according to the ASTM D-638 method using an ASTM No. 1 dumbbell test piece obtained by the above-mentioned injection molding and an ASTM No. 1 dumbbell test piece obtained by heat treatment in a gear oven.

Heat aging resistance: The ASTM No. 1 dumbbell test piece obtained by the above injection molding was subjected to a 150 ° C. gear oven (GPHH-200 manufactured by Tabai Espec Co., Ltd.).
(Type) and evaluated for 480 hours. The measurement items are tensile strength and color tone. Color tone: The YI value of a tensile test piece heat-treated in a gear oven was measured with an SM color computer (Suga Test Machine).

Surface appearance: The occurrence of cracks in the test pieces heat-treated in a gear oven and the surface condition of bleed-out were visually evaluated as follows.

Crack generation status None: ○, slight occurrence: Δ, clearly present: × Bleed-out None: ○, slightly present: Δ, large amount: × ・ Low mold depositability: mold clamping pressure 60 tons Cylinder temperature 220 ° C, mold temperature 8
Injection molding of ASTM No. 1 dumbbell specimen was performed at 0 ° C. and a molding cycle of 20 seconds. After continuous molding of 5,000 shots, the mold was observed, and whether or not a white solid substance was adhered was observed. The evaluation was performed according to the following criteria.
：: No deposit is observed. Δ: Slightly white solid adhered. X: Adhesion of a white solid substance is clearly observed.

The symbols of the additives used in Examples and Comparative Examples have the following structure names.

(1) Antioxidant AO-1: 5,7-di-t-butyl-3- (3,4di-methylphenyl) -3H-benzofuran-2-one

Embedded image AO-2: a compound having the following structural formula

Embedded image AO-3: a compound having the following structural formula

Embedded image AO-4: pentaerythritol tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] AO-5: 1,6-hexanediol-bis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] (2) HA-1: "Sanol" LS765 [Sankyo Co., Ltd.
Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate] (3) Formaldehyde scavenger F-1: benzoguanamine F-2: melamine F-3: cyanoguanidine Example 1 In a twin-screw extruder-type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 7.2), 30 kg / hr of trioxane and 1.0 kg of 1,3-dioxolane
/ Hr, a flow rate of 3.6 g / hr of boron trifluoride / diethyl etherate as a catalyst and a flow rate of a molecular weight regulator of 21 g / hr were respectively supplied to carry out continuous polymerization to obtain a crude polymer 29 as a fine white powder polymer. 0.4 kg / hr was obtained. 59 g of HA-1 "Sanol" 765 to this crude polymer
/ Hr to deactivate the catalyst, the antioxidant AO-
1 was added to 147 g / hr and calcium 12-hydroxystearate 44 g / hr, and “TEX-
44 "Feed to twin screw extruder, screw rotation speed 165rp
m, set temperature 245 ° C., residence time 5 minutes, stabilize by decomposing and removing unstable terminals of polymer.
A pellet of 8.7 kg / hr was obtained.

The obtained pellets were heated in a hot air drier at 80 ° C.
After drying for 4 hours, the test specimen was injection molded. Table 1 shows the evaluation results of the initial mechanical properties, the heat-treated aging test treatment sample, and the low mold deposit property. All physical properties are good.

Example 2 In a twin-screw extruder type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 7.2), trioxane 30 kg / hr and 1,3-dioxolane 1.0 kg /
hr, boron trifluoride / diethyl etherate as a catalyst was supplied at a flow rate of 3.6 g / hr and a molecular weight regulator was supplied at a flow rate of 21 g / hr, and continuous polymerization was carried out to obtain a coarse polymer 29 as a white fine powder polymer. 0.5 kg / hr was obtained. 59 g of HA-1 "Sanol" 765 to this crude polymer
/ Hr was added to deactivate the catalyst, and then the antioxidant AO-
148 g / hr and 44 g / hr calcium 12-hydroxystearate were added to the product “TEX-
44 ”Feed to twin screw extruder, screw rotation speed 150rp
m, set time 240 ° C., residence time 6 minutes, stabilized by decomposing and removing unstable terminals of polymer.
A pellet of 8.8 kg / hr was obtained.

Next, the pellets were dried with a hot air drier at 80 ° C. for 4 hours, and then the test pieces were injection molded. Initial mechanical properties,
Table 1 shows the results of the heat aging test sample and the evaluation results of the low mold depositability. All physical properties are good.

Example 3 Trioxane 30 kg / hr, 1,3-dioxolane 1.0 kg / h in a twin-screw extruder type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 7.2)
r, 3.6 g / hr of boron trifluoride / diethyl etherate as a catalyst and 21 g / hr of a molecular weight regulator were supplied, and continuous polymerization was carried out to obtain 29.8 kg / hr of a crude polymer which was a polymer of a white fine powder. Obtained. After adding 60 g / hr of HA-1 "Sanol" 765 to this crude polymer to deactivate the catalyst, 148 g of antioxidant AO-1 was added.
/ Hr, calcium 12-hydroxystearate 44
g / hr, and formaldehyde scavenger 30 g / hr
And supplied to a twin screw extruder “TEX-44” manufactured by Nippon Seisakusho. The screw rotation speed is 175 rpm, the set temperature is 250 ° C.,
The polymer was stabilized by decomposing and removing unstable terminals of the polymer at a residence time of 4 minutes to obtain pellets of 29.0 kg / hr.

Next, the pellets were dried with a hot air drier at 80 ° C. for 4 hours, and test pieces were injection molded. Initial mechanical properties,
Table 1 shows the results of the heat aging test sample and the evaluation results of the low mold depositability. All physical properties are good.

Example 4 In Example 3, the amount of the antioxidant added was 2 for AO-1.
2 g / hr, AO-2 83 g / hr, AO-3 43
Table 2 shows the results when g / hr was set. The physical properties of both the heat-aged aging test sample and the low mold deposit property are good.

Examples 5 and 6 Table 2 shows the test results of the samples obtained in Example 4 to which the formaldehyde scavengers F-2 and F-3 were added at 30 g / hr. Both the heat aging test and the low mold deposit properties are good.

Examples 7 and 8 In Example 2, 30 g of formaldehyde scavengers F-2 and 3 were added.
Table 2 shows the test results of the samples to which / hr was added. Both the heat aging test and the low mold deposit properties are good.

Comparative Example 1 A twin-screw extruder type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 7.2) was charged with 30 kg / hr of trioxane and 1.0 kg / hr of 1,3-dioxolane.
hr, 3.6 g / hr of boron trifluoride / diethyl etherate as a catalyst and 21 g / hr of a molecular weight modifier were supplied, respectively, and continuous polymerization was performed to obtain a coarse polymer as a fine white powder polymer. HA-1 "Sano
After adding 59 g / hr of 1 ″ 765 to deactivate the catalyst, 147 g / hr of antioxidant AO-4, 44 g / hr of calcium 12-hydroxystearate, and 30 g / hr of formaldehyde scavenger were added. 30. The mixture was supplied to a twin screw extruder “TEX-44” manufactured by Nippon Seisakusho, and stabilized by decomposing and removing unstable terminals of the polymer at a screw rotation speed of 165 rpm, a set temperature of 245 ° C., and a residence time of 5 minutes. A pellet of 5 kg / hr was obtained.

Next, the pellets were dried with a hot air drier at 80 ° C. for 4 hours, and then the test pieces were injection molded. Initial mechanical properties,
Table 2 shows the evaluation results of the samples subjected to the heat aging test and the low mold depositability. As a result of heat aging test and low mold deposit test,
In any case, good results were not obtained.

Comparative Example 2 In Comparative Example 1, the formaldehyde scavenger was 29 g / h.
Table 2 shows the test results of the samples to which r was added. As a result of the heat aging test and the low mold deposit test, no favorable results were obtained.

Comparative Example 3 Table 2 shows the test results of the sample of Comparative Example 1 except that the antioxidant was AO-5. As a result of the heat aging test and the low mold deposit test, no favorable results were obtained.

Comparative Example 4 Table 2 shows the test results of the sample obtained in Comparative Example 2 except that the antioxidant was AO-5. As a result of the heat aging test and the low mold deposit test, no favorable results were obtained.

[0054]

[Table 1]

[Table 2] From these results, it is clear that the polyoxymethylene resin composition of the present invention has excellent heat resistance and excellent molding characteristics.

[0055]

The polyoxymethylene resin composition of the present invention has excellent heat resistance and excellent molding characteristics. Therefore, the polyoxymethylene resin composition obtained by the present invention can be used for molded parts in all fields requiring heat resistance, for example, equipment parts such as automobiles, electric and electronic equipment, office equipment such as computers, other building piping, and miscellaneous goods. It can be suitably used for applications such as.

Claims (5)

[Claims] (A) 100 parts by weight of a polyoxymethylene resin (B) A polyoxymethylene resin composition comprising 0.001 to 3 parts by weight of a compound represented by the formula (R1 and R2 are alkyl groups). 2. A polyoxymethylene resin (A) based on 100 parts by weight of (C) And / or (D) 2. The polyoxymethylene resin composition according to claim 1, further comprising 0.001 to 3 parts by weight of a compound represented by the formula (R1 and R2 are alkyl groups). 3. A melamine as a formaldehyde scavenger based on 100 parts by weight of the polyoxymethylene resin (A).
The polyoxymethylene resin composition according to claim 1 or 2, further comprising 0.01 to 10 parts by weight of at least one compound selected from benzoguanamine and cyanoguanidine. 4. A polyoxymethylene resin (A) comprising trioxane, at least one cyclic ether or cyclic formal as a copolymerization component, boron trifluoride, boron trifluoride hydrate and boron trifluoride and oxygen At least one polymerization catalyst selected from a coordination compound with an organic compound containing an atom or a sulfur atom is added, and the (E) hindered amine compound is added to 100 parts by weight of a crude polymer obtained by polymerization. The polyoxymethylene resin composition according to any one of claims 1 to 3, wherein the catalyst deactivator is added by adding 3 to 3 parts by weight. 5. A crude polymer obtained by polymerizing trioxane and at least one kind of cyclic ether or cyclic formal as a copolymerization component is represented by the following formula: (Wherein R1 and R2 represent alkyl groups), and then the unstable terminal is removed to produce the polyoxymethylene resin composition according to claim 1. Of producing a polyoxymethylene resin composition.