JPH0521937B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to novel polyoxymethylene compositions. More specifically, the present invention relates to an antistatic polyoxymethylene composition having extremely excellent thermal stability and mechanical properties. Background Art Polyoxymethylene resin has excellent mechanical strength, creep properties, lubrication properties, and electrical properties, so it is used for example in automobile parts, electronic/electrical equipment parts,
Widely used for audio equipment parts. However, when used as a sliding member,
Since the generation of static electricity caused by friction is often seen as a problem in use, a desired amount of carbon black is added to the material. However, simply adding carbon black to polyoxymethylene resin inevitably leads to a decrease in thermal stability, fluidity, and mechanical properties, making it impossible to obtain a fully satisfactory polyoxymethylene resin composition. The problem arises. In order to solve this problem, an attempt has been made to add low density polyethylene together with conductive carbon black (Japanese Patent Application Laid-open No. 111348/1983), but this method requires a large amount of low density polyethylene. If it is not added, sufficient effects cannot be obtained, which has the disadvantage that the inherent mechanical properties of the polyoxymethylene resin are greatly impaired. Also,
Although it has been proposed to add an ethylene oxide adduct of an amide compound together with conductive carbon black (Japanese Patent Publication No. 31736/1983), this method does not provide a sufficiently satisfactory effect. Furthermore, it has been proposed to use lubricating oil in combination to prevent the decline in wear resistance and sliding properties that occur when blending conductive carbon black, and to maintain good formability. In this case, the mechanical properties inevitably deteriorate. Problems to be Solved by the Invention Under these circumstances, the present invention provides a polyoxymethylene resin composition that has antistatic properties and also has good thermal stability and mechanical properties. It was done for the purpose of Means for Solving the Problems As a result of intensive research to develop a polyoxymethylene resin composition having the above-mentioned excellent characteristics, the present inventors found that a polyoxymethylene resin composition containing a specific amount of conductive carbon black The inventors have discovered that the objective can be achieved by adding an epoxy compound and, if desired, an epoxy resin curing additive in a predetermined ratio to a methylene resin, and have completed the present invention based on this knowledge. That is, the present invention comprises (A) a polyoxymethylene resin, (B) a conductive carbon black with a dibutyl phthalate oil absorption of 200 ml/100 g or more, (C) an epoxy compound, and optionally (D) an epoxy resin curing additive. and based on the total composition weight, component (B) is from 0.5 to
30% by weight, component (C) 0.05-10% by weight, component (D)
The object of the present invention is to provide an antistatic polyoxymethylene resin composition characterized in that the amount thereof is in the range of 0.1 to 10% by weight. The polyoxymethylene resin used as component (A) in the present invention may be any commonly used polyoxymethylene and is not particularly limited. The conductive carbon black to be blended as component (B) is preferably one with a small particle size or a large surface area and a developed chain structure, but the oil absorption amount of dibutyl phthalate (hereinafter abbreviated as DBP) is preferable.
It must be 200ml/100g or more. This DBP oil absorption is a measure of the degree of development of the carbon black structure, and as the structure develops, the DBP oil absorption increases and the conductivity increases. The DBP oil absorption (ml/100g) can be determined by titrating a certain amount of carbon black stirred in a kneader mixer using DBP using an automatic brewet. In this titration, the freely flowing powder changes to semi-plastic properties when carbon black reaches its maximum DBP absorption (filling of voids), and the kneader torque increases rapidly. The required DBP amount (ml) is DBP
It is the oil absorption amount and is recognized as the structure index of ASTM D2415-65T. like this
Carbon black with a DBP oil absorption of less than 200ml/100g has too low a conductivity and must be added in large quantities to impart the desired antistatic properties, and the resulting composition This inevitably results in a significant decrease in the mechanical properties inherent in methylene resin. In the composition of the present invention, examples of conductive carbon black that can be used include Toka Black #4500 [oil absorption: 230ml/100g, manufactured by Tokai Carbon Co., Ltd.]
], #3750 [Oil absorption: 245ml/100g, Mitsubishi Kasei Co., Ltd.]
[Manufactured], Ketsuchen Black EC [Oil absorption: 350ml/
100g, manufactured by Lion Akzo Co., Ltd.], Ketsuchen Black ECDJ-600 [oil absorption capacity; 480ml/100g, manufactured by Lion Akzo Co., Ltd.], Printex XE2 [oil absorption capacity;
370ml/100g, manufactured by Degutsusa), but is not particularly limited to these. The content of these conductive carbon blacks is
Based on the weight of the composition, it is necessary to select the amount in the range of 0.5 to 30% by weight; if this amount is less than 0.5% by weight, the antistatic ability will not be sufficiently exhibited, while if it exceeds 30% by weight, the impact resistance will be significantly reduced. descend. The preferred amount is selected within the range of 2 to 20% by weight. In the composition of the present invention, the epoxy compound blended as component (C) is preferably a mono- or polyfunctional glycidyl derivative, such as 2-ethylhexyl glycidyl ether, 2-ethylhexyl glycidyl ether,
Methyl octyl glycidyl ether, lauryl glycidyl ether, stearyl glycidyl ether, behenyl glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether (units of ethylene oxide; 2 to 30), propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether ( Units of propylene oxide; 2-30), neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether ,
Bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, sorbitan monoester diglycidyl ether, sorbitan monoester triglycidyl ether, pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether,
Examples include, but are not limited to, diglycerin triglycidyl ether, diglycerin tetraglycidyl ether, cresol novolak, epichlorohydrin, and condensate (epoxy equivalent: 100-400, softening point: 20-150°C), etc. . Each of these epoxy compounds may be used alone or in combination of two or more, and the amount to be blended is determined based on the weight of the composition.
It is selected in the range of 0.05 to 10% by weight, preferably 0.5 to 7% by weight. If this amount is less than 0.05% by weight, the effect as a heat stabilizer will hardly be exhibited;
If it exceeds % by weight, the mechanical properties will be greatly reduced.
The optimum blending amount is appropriately selected depending on the type and amount of conductive carbon black used. In the composition of the present invention, a commonly used epoxy resin curing agent or a substance that accelerates curing of epoxy resin can be used as an epoxy resin curing additive as component (D), if desired. As the former epoxy resin curing agent, aliphatic and modified polyamines, modified aromatic amines, acids and acid anhydrides are mainly used. Examples of these epoxy resin curing agents include diethylenetriamine (DTA), triethylenetetramine (TTA), diethylaminopropylamine (DEPA), N-aminoethylpiperazine (N-AEP), benzyldimethylamine (BDMA), Nylene diamine (MPD), diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS),
Dicyandiamide, boron trifluoride monoethylamine ( _BF3・MEA), menthanediamine, xylylene diamine, bisaminopropyltetraoxaspiroundecane adduct (BATUA), imidazole, 2-ethyl-4-methylimidazole (EMI), anhydrous Phthalic acid (PA), maleic anhydride (MA), dodecylsuccinic anhydride (DDSA), hexahydrophthalic anhydride (HHPA), methylnadic anhydride (MNA), pyromellitic anhydride (PMDA), benzophenonetetracarboxylic anhydride Examples include, but are not limited to, acids (BTDA) and the like. These curing agents may be used alone or in combination of two or more. On the other hand, as a substance that accelerates the curing of epoxy resin, for example, the general formula (R ₁ in the formula has or does not have a substituent,
an alkyl group, an aryl group, an allyl group or a vinyl group; R ₂ , R ₃ and R ₄ are each a hydrogen atom or an alkyl group, an aryl group, an allyl group or a vinyl group with or without a substituent;
They may be the same or different from each other) Substituted imidazole compounds represented by the general formula (R ₅ in the formula has or does not have a substituent,
Alkyl group or aryl group having 8 or more carbon atoms, R ₆
and R ₇ are each an alkyl group or an aryl group with or without a substituent, and they may be the same or different. formula ( _R8 in the formula is an alkyl group or aryl group having 8 or more carbon atoms with or without a substituent) and a morpholine compound represented by the general formula [In the formula, R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each (-
C ₂ H ₄ O) _x --(-C ₃ H ₆ O) _y --H (Here, x and y have the relationship of x+y=1~20, x=0~20, y=0~20. A residue of a random copolymer or a block copolymer represented by the number satisfying the following formula, which may be the same or different from each other. Examples include dicyandiamide derivatives represented by the formula be able to. In these compounds, R ₁ , R ₂ , R ₃ , R ₄ ,
When R ₆ and R ₇ are alkyl groups, the number of carbon atoms is preferably in the range of 1 to 30, and
When R ₅ and R ₈ are alkyl groups, the number of carbon atoms is preferably in the range of 8 to 30. Examples of the substituted imidazole compound represented by the general formula () include 1-hydroxyethyl-2-methylimidazole, 1-cyanoethyl-
2-heptadecyl imidazole, 1-vinyl-2
-phenylimidazole, 1-lauryl-2-undecylimidazole, 1-allyl-2-isopropylimidazole, 1-benzyl-2-ethylimidazole, 1-stearyl-2-methyl-4
-ethylimidazole, 1-ethyl-5-laurylimidazole, 1-phenyl-4-ethylimidazole, 1-tolyl-2-heptadecyl imidazole, 1-triphenylmethylimidazole,
1-(Behenylbenzyl)-2-methylimidazole, 2-(Behenylbenzyl)imidazole, 4
-(behenylbenzyl)imidazole, 5-(behenylbenzyl)imidazole, etc., but are not particularly limited thereto. Examples of the tertiary amine compound represented by the general formula () include octyldimethylamine,
Octyldiethylamine, dioctylmethylamine, trioctylamine, stearyldimethylamine, stearyldiethylamine, distearylmethylamine, distearylpropylamine, tristearylamine, behenylstearylmethylamine, behenyldimethylamine, behenyldiethylamine, dibehenylmethylamine, dibehenyl Isopropylamine, tribehenylamine, trilaurylamine, octyldihydroxyethylamine, benzyldimethylamine, benzyldibutylamine, benzylstearylmethylamine,
p-octylphenyldimethylamine, trisdimethylaminobenzene, trisdimethylaminophenol, trisdimethylaminotoluene, tris(dimethylaminomethyl)phenol, triphelamine, tritolylamine, diphenyltolylamine, (behenylbenzyl)dimethylamine,
Examples include di(behenylbenzyl)methylamine, but are not particularly limited thereto. Examples of the morpholine compound represented by the general formula () include cutylmorpholine, laurylmorpholine, cetylmorpholine, stearylmorpholine, behenylmorpholine, phenylmorpholine, p-laurylphenylmorpholine, tolylmorpholine, benzylmorpholine, p-methyl Examples include benzylmorpholine, behenylbenzylmorpholine, and the like, but are not particularly limited thereto. The dicyandiamide derivative represented by the general formula () is obtained by adding ethylene oxide or propylene oxide or both to dicyandiamide, and as such,
For example, 4 molar EO adduct of dicyandiamide, 4 molar PO adduct of dicyandiamide, 10 molar EO adduct of dicyandiamide, 10 molar PO adduct of dicyandiamide,
20 mol EO adduct, 20 mol to dicyandiamide
PO adduct, 40 molar EO adduct to dicyandiamide, 40 molar PO adduct to dicyandiamide, 60 molar EO adduct to dicyandiamide, 60 molar PO adduct to dicyandiamide, 80 molar EO adduct to dicyandiamide, dicyandiamide to
80 mol PO adduct, 4 mol to dicyandiamide
EO/7 mol PO copolymer adduct, 4 mol EO/20 mol PO copolymer adduct to dicyandiamide, 4 mol EO/40 mol PO copolymer adduct to dicyandiamide, 4 mol EO/60 mol PO to dicyandiamide
Copolymerization adduct, 4 mol to dicyandiamide
EO/70 mol P copolymer adduct, 10 mol EO/7 mol PO copolymer adduct to dicyandiamide, 10 mol EO/20 mol PO copolymer adduct to dicyandiamide, 10 mol EO/30 mol PO to dicyandiamide
Copolymer adduct (however, all four active hydrogens of dicyandiamide contain 1 mol or more of EO or PO)
is added to one active hydrogen.
The total number of added moles of EO and PO does not exceed 20 moles), but is not particularly limited to these. These epoxy resin curing accelerators may be used alone or in combination of two or more. Furthermore, in the present invention, one or more types of epoxy resin curing agents and one or more types of epoxy resin curing accelerators can be used in combination. In the composition of the present invention, the amount of the epoxy resin curable additive blended as component (D) is 0.1 to 10% by weight, preferably 0.5 to 7% by weight, based on the weight of the composition.
Selected within the range of weight %. If this amount is less than 0.1% by weight, the effect of the epoxy compound as a heat stabilizer cannot be sufficiently improved, while if it exceeds 10% by weight, the mechanical properties will be significantly reduced. The optimal blending amount of this component (D) is appropriately selected depending on the type and amount of the conductive carbon black and epoxy compound used. The polyoxymethylene resin in the composition of the present invention may be a polyoxymethylene homopolymer or a polyoxymethylene copolymer or terpolymer consisting mostly of oxymethylene chains, such as trioxane, tetraxane, etc., which are cyclic oligomers of formaldehyde or polardehyde. It is obtained by polymerizing or copolymerizing these alone or with a comonomer that can be copolymerized with them, and is stabilized against decomposition from the terminal, and usually stabilizers and antioxidants are added. things are used. The composition of the present invention can be prepared by combining each component with, for example, a kneader,
It can be prepared by melt-kneading using a known device usually used for kneading resin melts, such as a roll mill or an extruder. As a melt-kneading device, an extruder is most suitable from the viewpoints of blocking oxygen and working environment. Types of extruders include single-screw, twin-screw, vented, and non-vented extruders, and the composition of the present invention can be prepared using any of these extruders. The mixing temperature is higher than the melting point of the polyoxymethylene resin used, and extrusion is sufficiently possible at the commonly used temperature in the range of 180 to 230°C. The time required for kneading is approximately the same as the time required for extruding the polyoxymethylene resin alone. The kneading conditions for preparing the composition of the present invention have been shown above, but the kneading method and conditions are not limited to the above, and may be any known method or method used to prepare a polyoxymethylene composition. Any conditions can be used. The composition of the present invention may contain, if desired, various additives commonly used in ordinary polyoxymethylene compositions, such as pigments, fillers, lubricants, and the like. Effects of the Invention The polyoxymethylene composition of the present invention includes a polyoxymethylene resin containing an epoxy compound together with conductive carbon black, or an epoxy compound and an epoxy resin curing agent or curing accelerator together with conductive carbon black. Therefore, we have created a composition that retains the antistatic properties of conductive carbon black, greatly improves the reduction in thermal stability of polyoxymethylene resin caused by conductive carbon black, and maintains the mechanical properties of polyoxymethylene resin. It is. The epoxy resin curable additive used in the composition of the present invention has the effect of enhancing the effect of the epoxy compound added as component (C) as a heat stabilizer, and has the effect of enhancing the effect of the epoxy compound added as component (C) as a heat stabilizer. Combinations of only curing agents and curing accelerators do not exhibit much of the effect of their addition. Moreover, the effect of the present invention is that the general formulas () to ()
This effect is particularly great when a substance that accelerates the curing of the epoxy resin represented by the formula is added. Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, each characteristic of the composition was determined as follows. (1) ST value The resin composition was retained in an injection molding machine [ArburgAllrounder 100; manufactured by Western Trading Co., Ltd.] with a cylinder temperature of 230°C.
When a molded piece of ×3 × 120 mm was molded, the critical residence time (minutes) at which silver streaks appeared on 2/3 of the surface of the molded piece was defined as the ST value. (2) Ra value The weight residual rate (%) when the composition was heated in air at 230°C for 120 minutes was defined as the Ra value. (3) Surface electrical resistance The composition was molded into a molded piece of 130 x 110 x 3 mm using the injection molding machine, and measured using the molded piece and an insulation resistance measurement sample box TR-42 (manufactured by Takeda Riken). Examples 1 to 36 Polyoxymethylene copolymer [Tenatsuku-
C7510 (melt index 30g/10 minutes); Asahi Kasei
Co., Ltd. registered trademark] Pulverized product, conductive carbon black,
Epoxy compounds, epoxy resin curing additives,
After compounding using a Henschel mixer at the compounding ratios shown in Tables 1 to 9, the cylinder temperature was
The mixture was kneaded into pellets using a 30 mmφ twin-screw extruder set at 190°C and a screw rotation speed of 150 rpm. The ST value and Ra value of this pellet were measured, and test pieces were molded using a molding machine and the flexural modulus and surface electrical resistance were measured. The results are shown in Tables 1 to 9.

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[Table] Comparative Examples 1 to 9 Polyoxymethylene resin [Tenatsuku-C7510
(copolymer, melt index 30g/10 minutes),
Or Tenatsuku 7010 (homopolymer, melt index 30g/10 minutes); Asahi Kasei Corporation registered trademark] crushed product,
Conductive carbon black, stearic acid diethanolamide, low density polyethylene, epoxy compounds, and epoxy resin curing additives in Tables 10 and 11.
30 mm after mixing using a Henschel mixer at the mixing ratio shown in the table and setting the cylinder temperature to 190℃.
The mixture was kneaded into pellets using a φ twin-screw extruder at a screw rotation speed of 150 rpm. The ST value of this pellet is
The Ra value (described above) was measured, and a test piece was molded using a molding machine to measure the flexural modulus of elasticity and surface electrical resistance. The results are shown in Tables 10 and 11.

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[Table] Examples 37-48 Polyoxymethylene polymer [Tenatsuku]
7010 (melt index 30g/10 minutes); Asahi Kasei Corporation
Registered trademark: Pulverized product, conductive carbon black, epoxy compound, epoxy resin curing additive, No. 12
After mixing using a Henschel mixer at the compounding ratios shown in Table 14, the mixture was kneaded into pellets using a 30 mmφ twin-screw extruder with a cylinder temperature of 190° C. and a screw rotation speed of 150 rpm. The ST value and Ra value (described above) of this pellet were measured, and test pieces were molded using a molding machine and the flexural modulus and surface electrical resistance were measured. The results are shown in Tables 12-14.

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Claims (1)

[Claims] 1 Consisting of (A) polyoxymethylene resin, (B) conductive carbon black with an oil absorption of dibutyl phthalate of 200 ml/100 g or more, and (C) an epoxy compound, and based on the total composition weight, the components An antistatic polyoxymethylene resin composition characterized in that (B) is in the range of 0.5 to 30% by weight and component (C) is in the range of 0.05 to 10% by weight. 2 Consisting of (A) polyoxymethylene resin, (B) conductive carbon black with dibutyl phthalate oil absorption of 200 ml/100 g or more, (C) epoxy compound, and (D) epoxy resin curing additive, and total composition weight Based on
An antistatic polyoxymethylene resin composition characterized in that component (D) is in a range of 0.1 to 10% by weight. 3 The epoxy resin curing additive has the general formula (R ₁ in the formula has or does not have a substituent,
an alkyl group, an aryl group, an allyl group or a vinyl group; R ₂ , R ₃ and R ₄ are each a hydrogen atom or an alkyl group, an aryl group, an allyl group or a vinyl group with or without a substituent;
They may be the same or different from each other) Substituted imidazole compounds represented by the general formula (R ₅ in the formula has or does not have a substituent,
Alkyl group or aryl group having 8 or more carbon atoms, R ₆
and R ₇ are each an alkyl group or an aryl group with or without a substituent, and they may be the same or different. formula (R ₈ in the formula has or does not have a substituent,
a morpholine compound represented by (which is an alkyl group or aryl group having 8 or more carbon atoms), and [R ₉ , R ₁₀ , R ₁₁ and R ₁₂ in the formula are each (-C ₂ H ₄ O) _x --(-C ₃ H ₆ O) _y --H (here, x and y are x+y = 1 to 20, x = 0 to 20, y = 0 to 20) are residues of a random copolymer or block copolymer, and they may be the same The composition according to claim 2, wherein the composition is at least one curing accelerator selected from among dicyandiamide derivatives represented by the following formula.