JPH02102238A - Plastic magnet composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. with excellent long-term heat stability by compounding a compsn. consisting of a polyolefin and a magnetic powder with a specified zinc salt of an org. sulfur compd. and a metal inactivating agent. CONSTITUTION:100 pts.wt. compsn. consisting of 5-20wt.% polyolefin (e.g., ethylene-propylene block copolymer) and 80-95wt.% magnetic powder (e.g., barrium ferrite) are compounded with each 0.01-5 pts.wt. one or more zinc salts of org. sulfur compd. selected from zinc alkyl sulfates (e.g., zinc methyl sulfate), zinc sulfonate (e.g., zinc methylsulfonate), zinc dithiocarbamate (e.g., zinc dinonyldithiocarbamate) and zinc mercaptobenzothiazole and a heavy metal inactivating agent (e.g., 2,4,6-triamino-1,3,5-triazine) to constitute the title compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plastic magnet composition. More specifically, the present invention relates to a plastic magnet composition from which a molded article with excellent resistance to thermal oxidative deterioration during practical use can be obtained.

[Prior Art] Sintered ferrite magnets, samarium cobalt alloy magnets, and the like have been widely used as permanent magnets in the fields of heavy electrical appliances, home appliances, electronic devices, and the like. However, these magnets are mechanically brittle and require secondary processing such as cutting and polishing, which poses a serious obstacle to expanding their use in the above-mentioned fields.

Therefore, in order to solve the above-mentioned drawbacks, a composite material, so-called plastic magnet, in which magnetic powder is blended with various synthetic resins, has been developed and is now widely put into practical use. However, when polyolefins, especially propylene-based polymers, are used as synthetic resins for plastic magnets, propylene-based polymers contain tertiary carbon, which is susceptible to oxidation, and therefore are not included in the magnetic powder. Molded products using plastic magnets are catalytically oxidized and degraded by various metal ions contained in the magnets, so molded products using plastic magnets have high thermal oxidation resistance (hereinafter referred to as long-term thermal stability) during practical use.
The disadvantage is that LAt, τ is significantly reduced.

For this reason, in order to improve the long-term thermal stability of molded products made from plastic magnets using polyolefin, we have developed compositions in which heavy metal deactivators are blended with plastic magnets, and molding machines for molding the compositions. A composition has been proposed in which a lubricant is used in combination to reduce the kneading torque or improve mold release properties during molding, and to smooth the surface of the molded product (Japanese Patent Laid-Open No. 16985/1983).
Publication No. 8).

[Problems to be Solved by the Invention] However, the above-mentioned Japanese Patent Application Laid-Open No. 1983-1999, in which a heavy metal deactivator is blended into a plastic magnet using polyolefin,
Although the plastic magnet composition proposed in Japanese Patent No. 169858 has considerably improved long-term thermal stability, it is still not fully satisfactory. Furthermore, in the above-mentioned JP-A-62-169858, there is no mention of a zinc salt of an organic sulfur compound as a lubricant used in combination, and there is no suggestion that the zinc salt improves the long-term thermal stability of the plastic magnet composition. There is no mention of it.

The inventors of the present invention have conducted extensive research in order to obtain a composition that solves the above-mentioned problems regarding plastic magnet compositions, that is, a plastic magnet composition that has improved long-term thermal stability.

As a result, a zinc salt of one or more organic sulfur compounds selected from zinc salts of alkyl sulfate, zinc sulfonate, zinc dithiocarbamate, and mercaptobenzothiazole was added to a plastic magnet made of polyolefin and magnetic powder. , is called compound A.

) and a heavy metal deactivator in specific amounts, it was discovered that a plastic magnet composition with improved long-term thermal stability could be obtained, and based on this knowledge, the present invention was completed.

As is clear from the above description, an object of the present invention is to provide a plastic magnet composition which, when formed into a molded article, has excellent long-term thermal stability.

[Means to solve the problem] The present invention has the following configuration.

5 to 20% by weight of polyolefin and 80 to 80% of magnetic powder
Zinc salts of one or more organic sulfur compounds selected from zinc salts of alkyl sulfates, zinc sulfonates, zinc dithiocarbamates, and mercaptobenzothiazoles per 100 parts by weight of a composition consisting of 95% by weight. Hereinafter, it will be referred to as compound A.

) and a heavy metal deactivator in an amount of 0.01 to 5 parts by weight, respectively.

The polyolefin used in the present invention is a crystalline homopolymer of α-olefin such as ethylene, propylene, butene-1, pentene-1,4-methyl-pentene-1, hexene-1, octene-1, or two or more of these. Polyolefins such as crystallinity, low crystallinity or non-crystalline random copolymers or crystalline block copolymers of α-olefins, amorphous ethylene-propylene-nonconjugated diene ternary copolymers, the above-mentioned α-olefins, etc. A copolymer of olefin and vinyl acetate or acrylic ester, a saponified product of the copolymer,
Copolymers of these α-olefins and unsaturated silane compounds, copolymers of these α-olefins and unsaturated carboxylic acids or their anhydrides, reaction products of these copolymers and metal ion compounds, Examples include modified polyolefins obtained by modifying polyolefins with unsaturated carboxylic acids or derivatives thereof, and silane-modified polyolefins obtained by modifying the above-mentioned polyolefins with unsaturated silane compounds.
It is also possible to use a mixture of more than one type of polyolefin. In addition to the polyolefins mentioned above, various synthetic rubbers (e.g. polybutadiene, polyisoprene, polychloroprene,
Chlorinated polyethylene, chlorinated polypropylene, fluororubber, styrene-butadiene rubber, acrylonitrile-
butadiene rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene ethylene-butylene-styrene block copolymer, styrene-propylene-butylene-styrene block copolymer, etc.) or Thermoplastic synthetic resins (e.g. polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyamide, polyethylene terephthalate,
(polybutylene terephthalate, polycarbonate, polyvinyl chloride, fluororesin, etc.) can also be used in combination. Crystalline propylene homopolymer, crystalline propylene copolymer containing 70% by weight or more of a propylene component, including crystalline ethylene-propylene random copolymer, crystalline ethylene-propylene block copolymer, crystalline propylene- Particularly preferably used are butene-1 random copolymer, crystalline ethylene-propylene-butene-13-element copolymer, crystalline propylene-hexene-butene-13-element copolymer, and mixtures of two or more thereof.

Magnetic powders used in the present invention include manganese ferrite, nickel ferrite, zinc ferrite, manganese-zinc ferrite, manganese-zinc-iron ferrite, nickel-zinc ferrite, cobalt-iron ferrite, manganese-magnesium-aluminum ferrite, strontium ferrite, Examples include ferrite-based magnetic powders such as barium ferrite, chromium ferrite, calcium ferrite, lead ferrite, and sodium-lanthanum ferrite, and rare earth cobalt-based magnetic powders such as samarium cobalt, with strontium ferrite and barium ferrite being particularly preferred. The particle size of these magnetic powders is not particularly limited, but is usually 0.5μ to 50μ
[mu], preferably 0.5[mu] to 10[mu], most preferably 1[mu] to 5[mu]. In addition, these magnetic powders can be used with known surface treatment agents such as silane coupling agents, titanate coupling agents, boron coupling agents, aluminate coupling agents, and zircoaluminate coupling agents. When used after pre-surface treatment with
The compatibility and dispersibility between the magnetic powder and the polyolefin are improved, excellent moldability is obtained, and the mechanical strength of the molded product when made from the plastic magnet composition is improved. Therefore, it is preferable to use magnetic powder whose surface has been treated with a surface treatment agent. Of course, these magnetic powders can be used alone, but two or more types of magnetic powders can also be used in combination. The blending ratio of the magnetic powder is
80-95 for a composition consisting of polyolefin and magnetic powder! ! The amount is %. When the content is 80% by weight, the moldability of the plastic magnet composition is good, but the magnetic properties are insufficient, and when the content exceeds 95% by weight, the moldability becomes difficult and the resulting molded product has poor mechanical properties. The strength also decreases, making it impractical.

Compound A used in the present invention includes zinc methyl sulfate, zinc ethyl sulfate, zinc-n-propyl sulfate, zinc-1-propyl sulfate, zinc-n-butyl sulfate, zinc-1-butyl sulfate, zinc-5-butyl sulfate,
Zinc-butyl sulfate, zinc-n-amyl sulfate, zinc-1-amyl sulfate, zinc-5-amyl sulfate, zinc-butyl sulfate, zinc hexyl sulfate, zinc-n-
Octyl sulfate, zinc-2-ethylhexyl sulfate, zinc octyl sulfate, zinc nonyl sulfate, zinc lauryl sulfate,
Zinc tridecyl sulfate, zinc myristyl sulfate, zinc quercil sulfate, zinc stearyl sulfate, zinc oleyl sulfate, zinc crinolyl sulfate, zinc crylyl sulfate, zinc behenyl sulfate, zinc quercyl sulfate, zinc lignoserinyl sulfate, zinc cellulose nyl sulfate, zinc quercyl sulfate,
Zinc alkoxypolyoxyethylene ether sulfate, zinc alkoxypolyoxypropylene ether sulfate, zinc alkylphenoxy polyoxyethylene ether sulfate, zinc alkylphenoxy polyoxypropylene ether sulfate, zinc methyl sulfonate, zinc ethyl sulfonate,
Zinc-n-propylsulfonate, zinc-1-propylsulfonate, zinc-n-butylsulfonate, zinc-1-butylsulfonate, zinc-5
-butyl sulfonate, zinc butyl sulfonate, zinc low amyl sulfonate, zinc
1-amyl sulfonate, zinc-8-amyl sulfonate, zinc-1-amyl sulfonate, zinc hexyl sulfonate, zinc-n-octyl sulfonate, zinc-2-ethylhexyl sulfonate , zinc-1-octyl sulfonate, zinc nonyl sulfonate, zinc lauryl sulfonate, zinc tridecyl sulfonate, zinc myristyl sulfonate, zinc queryl sulfonate, zinc stearyl sulfonate, zinc oleyl sulfonate Zinc crinolyl sulfonate, zinc crinolyl sulfonate, zinc behenyl sulfonate, zinc quercyl sulfonate, zinc lignoserinyl sulfonate, zinc serotinyl sulfonate, zinc quercyl sulfonate, zinc benzene sulfonate Nate,
zinc-p-)luenesulfonate, zinc-p-t
-butylbenzenesulfonate, zinc-p-dodecylbenzenesulfonate, zinc-p-phenolsulfonate, zincnaphthalene-α-sulfonate, zincnaphthalene-β-sulfonate, zinc dimethyl-dithiocarbamate, zinc diethyl-dithio Carbamate, zinc di-butyl-dithiocarbamate, zinc dinonyl-dithiocarbamate, zinc whaleuryl-dithiocarbamate, zinc methyl-phenyl-dithiocarbamate, zinc ethyl-phenyl-dithiocarbamate, zinc diphenyl-dithiocarbamate, zinc ditolyl-dithiocarbamate, zinc dibenzyl - dithiocarbamates and zinc mercaptobenzothiazole, in particular zinc stearyl sulfate, zinc stearyl sulfonate, zinc-p-dodecylbenzenesulfonate, zinc-P
-phenol sulfonate, zinc dimethyl-dithiocarbamate, zinc diethyl-dithiocarbamate,
Zinc di-n-butyl-dithiocarbamate, zinc dinonyl-dithiocarbamate, zinc ethyl-phenyl-dithiocarbamate and zinc mercaptobenzothiazole are preferred. Of course, these compounds A can be used alone, but two or more kinds of compounds A can also be used in combination. The compounding ratio of compound A is 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, per 100 parts by weight of the composition, which contains 5 to 20% by weight of polyolefin and 80 to 95% by weight of magnetic powder. Parts by weight. If the amount is less than 0.01 parts by weight, the effect of improving the long-term thermal stability of the plastic magnet composition will not be sufficiently exhibited, and if it is more than 5 parts by weight, the effect of improving the long-term thermal stability will not be sufficiently exhibited. Not only is it impractical as it cannot be expected to do so, but it is also uneconomical.

Heavy metal deactivators used in the present invention include benzotriazole, 2,4.6-triamino-1,3,5-triazine, 3,9-bis[:2-(3,5-diamino-2,4 ,6-)riazaphenyl)ethyl] -2,4
, 8,10-tetraoxaspiro[5,5]undecane, ethylenediaminetetraacetic acid, alkali metal salt of ethylenediamine-tetraacetic acid, N.

N'-disalicylidene-ethylenediamine, N, N'-disalicylidene-1,2-propylenediamine, N.

N T I-disalicylidene-N'-methyl-dipropylene triamine, 3-salicyloyl amino-1,2,4
-) Riazole, decamethylene dicarboxylin acid-bis(N'-salisilylhydrazide), nickel-bis(1-phenyl-3-methyl-4-decanoyl-5-virazolate), 2-ethoxy-2'-ethyloxa Nilide, 5-t-butyl-2-ethoxy-2'-ethyloxanilide, N,N-diethyl-N',N'-diphenyloxamide, N,N'-diethyl-N,N'-
diphenyl oxamide, oxalink acid bis(
benzylidene hydrazide), thiodiprobionic acid bis(benzylidene hydrazide), isophthalic acid bis(2-phenoxypropionyl hydrazide), bis(salicyloylhydrazine), N-salicylidene-N'-salicyloylhydrazone, N , N'bis[3-(3,5-di-butyl-4-hydroxyphenyl)probionylcohydrazine, tris[2-butyl-4-thio(2'-methyl-42-hydroxy-5
'-71butylphenyl)-5-methylphenyl coffosphite and N,N'-bis[2-(3-(3,5
Examples include -dibutyl-4-hydroxyphenyl)propionyloxy]ethyl]oxamide, in particular 2,4.6-)riamino-1,3,5-triazine,
3,9-bis[2-(3,5-diamino-2,4,6-
triazaphenyl)ethylco2.4,8.10-tetraoxaspiro[5,5oundecane.

Oxalic acid bis(benzylidene hydrazide), N,N'-bis[3-(3,5-di-butyl-4-hydroxyphenyl)propionyl]hydrazine,
Tris[2-butyl-4-thio(2'-methyl-4
'-Hydroxy-5'-t-butylphenyl)-butylphenyl]phosphite and N,N'-bis[2
-(3-(3,5-di-butyl-4-hydroxyphenyl)propionyloxy]ethyl]oxamide is preferred. It is natural to use these heavy metal deactivators alone, but it is also possible to use two or more types of heavy metal deactivators. A compounding ratio of the heavy metal deactivator is 0.01 to 5 parts by weight per 100 parts by weight of a composition consisting of 5 to 20% by weight of polyolefin and 80 to 95% by weight of magnetic powder. parts, preferably 0.05 to 2 parts by weight.If 0.01 parts by weight is added to the bottom groove, the effect of improving the long-term thermal stability of the plastic magnet composition will not be sufficiently exhibited, and even if it exceeds 5 parts by weight, Although this is acceptable, it is not only impractical as no further improvement in long-term thermal stability can be expected, but is also uneconomical.

The composition of the present invention includes various additives that are usually added to polyolefins, such as phenol-based, thioether-based, phosphorus-based antioxidants, light stabilizers, clarifying agents, etc.
Nucleating agents, lubricants, antistatic agents, antifogging agents, antiblocking agents, anti-drop agents, pigments, radical generators such as peroxides,
Dispersants or neutralizing agents for metal soaps, inorganic fillers (
For example, talc, mica, clay, wollastonite,
Zeolite, asbestos, calcium carbonate, aluminum hydroxide, magnesium hydroxide, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, zinc sulfide, barium sulfate, calcium silicate, aluminum silicate, glass fiber, potassium titanate, carbon fiber , carbon black, graphite, metal fibers, etc.) or coupling agents (such as silane-based, titanate-based, boron-based,
For the purpose of the present invention, the inorganic filler or organic filler (for example, wood flour, pulp, waste paper, synthetic fiber, natural fiber, etc.) that has been surface-treated with a surface treatment agent such as aluminate-based, zirco-aluminate-based, etc. They can be used together as long as they do not cause any damage. In particular, when a phenolic antioxidant is used in combination, the effect of preventing oxidative deterioration is exhibited synergistically, so it is preferable to use them together.

As a phenolic antioxidant, 2,6-diphenyl-
4-octadecyloxyphenol, 2,4-bis(n-
octylthio)-6-(4-hydroxy-3,5-di-butylanilino)-1,3,5-)riazine, 2
, 4.6-) Lis(3', 5ξ di-t-butyl-4'
-hydroxybenzylthio)-1,3,5-triazine, 1,1.3-)lis(5-t-butyl-4-hydroxy-2-methylphenyl)-butane, bis[3,3-
Bis(4'-hydroxy-3'-t-butylphenyl)
butyric acid] ethylene glycol ester, bis[3,3-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid]-2,2-bis(hydroxyethoxyphenyl)propane ester, bis[
3,3-bis(4'-hydroxy-3'-methyl-5'
- Sheeptylphenyl) Ptyric Acid Coz,z
-His(hydroxyethoxyphenyl)propane ester, bis[3,3-bis(4'-hydroxy-3',5
'-butylphenyl) butyric acid]
-2,2-bis(hydroxyethoxyphenyl)propane ester, bis[2-(3'-t-butyl-2'-hydroxy-51-methylbenzyl)-S-t-butyl-
4-methylphenylcoterephthalate, 3,9-bis[
l, 1-dimethyl-2-(β-(3-t-butyl-4-
hydroxy-5-methylphenyl)propionyloxy)ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 3,9-bis[1,1-dimethyl-2-(β-(3 , butyl-4-hydroxyphenyl)propionyloxy)ethyl] -2,4
, 8,10-tetraoxaspiro[5,5]undecane, 3,9-bis[1,1-dimethyl-2-(β-(3,
5-diphenyl-4-hydroxyphenyl)propionyloxy)ethyl]-2.4,8.10-tetraoxaspiro[5,5]undecane, 3,9-bis[1,1-
Dimethyl-2-(β-(3,5-dicyclohexyl-4
-hydroxyphenyl)propionyloxy)ethyl]
-2,4,8,10-tetraoxaspiro[5,5]
undecane, 1,3.5-)dimethyl-2゜4.6-
Tris(3,5-di-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-hydroxybenzyl) -butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate,
1,3,5-tris[(3,5-di-butyl-4-
hydroxyphenyl)propionyloxyethyl coin cyanurate, 2,2bis[4-(2-(3-methyl-
5-tert-butyl-4-hydroxyphenylpropionyloxy)ethoxy]phenyl]propane, 2,2-bis[4-(2-(3,5-di-butyl-4-hydroxyphenylpropionyloxy)ethoxy)phenylco propane, tetrakis[methylene-3-(3'-methyl-5'-butyl-4'-hydroxyphenyl)propionate comethane and tetrakis[methylene-3-
Examples include (3',5'-di-L-butyl-4'-hydroxyphenyl)propionate comethane, particularly 1,3,5-)dimethyl-2,4,6-tris(3
, 5-di-butyl-4-hydroxybenzyl)benzene, 1,3.5-)lis(3,5-di-butyl-4-hydroxybenzyl)isocyanurate, 3,9
-bis[1,1-dimethyl-2-(β-(3-sebutyl-4-hydroxy-5-methylphenyl)propionyloxy)ethyl]-2.4,8.10-tetraoxaspiro[5,5] undecane, 1,3.5-tris [(
3, t-butyl-4-hydroxyphenyl)propionyloxyethylcoin cyanurate, 2,2-bis[4-(2-(3,5-butyl-4-hydroxyphenylpropionyloxy)ethoxy]phenyl) Propane and tetrakis[methylene-3-(3″5
1-di-butyl-4'-hydroxyphenyl)propionate comethane is preferred.

It is natural to use these phenolic antioxidants alone, but it is also possible to use two or more types of phenolic antioxidants in combination. The blending ratio of the phenolic antioxidant is 5 to 20% by weight of polyolefin and 80 to 9% by weight of magnetic powder.
0.05 per 100 parts by weight of a composition consisting of 5% by weight
-5 parts by weight, preferably 0.05-2 parts by weight. 0
．． If the amount is less than 5 parts by weight, the synergistic effect of improving the long-term thermal stability of the plastic magnet composition will not be sufficiently exhibited, and if it is more than 5 parts by weight, the synergistic effect of improving the long-term thermal stability will not be sufficiently exhibited. Not only is it impractical as it cannot be expected to do so, but it is also uneconomical.

The composition of the present invention is prepared by mixing polyolefin with predetermined amounts of magnetic powder, Compound A, a heavy metal deactivator, and the above-mentioned various additives that are usually added to polyolefin using a conventional mixing device such as a Hensel mixer (trade name). Mix using a Super Mixer, Ribbon Blender, Pan Bali Mixer, etc., and then mix with a normal single screw extruder, twin screw extruder, Brabender or roll, etc. at a melt mixing temperature of 170℃ to 30℃.
It can be obtained by melt-kneading and pelletizing at 0°C, preferably 200°C to 270°C. In particular, it is preferable to use a twin-screw extruder because the dispersibility of the magnetic powder is improved and a uniform composition can be obtained. The obtained composition is used to produce a desired molded article by various molding methods such as injection molding, extrusion molding, and blow molding, especially injection molding. In addition, by performing magnetic field orientation in the above-mentioned various molding methods, products with excellent magnetic properties can be obtained.

[Function] In the present invention, the heavy metal deactivator is generally known to inactivate the catalytic oxidative deterioration effect of polyolefins caused by heavy metal ions.
The mechanism of action of organic sulfur compounds in the zinc range itself is not clear. However, by using Compound A in combination with a plastic magnet composition containing a heavy metal deactivator, a surprising synergistic effect that could not be expected from the combination of conventionally known compounds that have an oxidative deterioration prevention effect is exhibited. The long-term thermal stability of the plastic magnet composition was significantly improved.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples, Comparative Examples, and Production Examples, but the present invention is not limited thereto.

The evaluation method used in Examples and Comparative Examples was as follows.

1) Long-term thermal stability: Evaluated by oven life test. That is, using the obtained pellets, a test piece with a length of 50 mm, a medium size of 5011 nm, and a thickness of 2 mm was made by injection molding, and the test piece was placed in a circulating hot air oven adjusted to a temperature of 150°C to ensure that the test piece was completely sealed. Time until deterioration (
Measurement (time until tensile strength becomes 0) (JIS
Long-term thermal stability was evaluated according to K 7212).

Production Example 1 99% by weight of strontium ferrite with an average particle size of 1.1μ as a magnetic powder and 1% by weight of n-octadecyltriethoxysilane as a surface treatment agent were placed in a Hensel mixer (trade name) and mixed by stirring for 5 minutes. A surface-treated magnetic powder (1) was obtained.

Production Example 2 99% by weight of barium ferrite with an average particle size of 1.1μ as a magnetic powder and 1% by weight of isopropyl triisostearoyl titanate as a surface treatment agent were placed in a Hensel mixer (trade name) and mixed by stirring for 5 minutes. A surface-treated magnetic powder (II) was obtained.

Production Example 3 99% by weight of strontium ferrite with an average particle size of 1.1μ as magnetic powder and 1% by weight of acetalkoxyaluminum diisopropylate as a surface treatment agent were placed in a Hensel mixer (trade name) and mixed with stirring for 5 minutes. A surface-treated magnetic powder (III) was obtained.

Examples 1 to 12, Comparative Examples 1 to 8 MFR (load 2 at 230°C) as polyolefin
．． 15% by weight of unstabilized powdered crystalline ethylene-propylene block copolymer (ethylene content 8.5% by weight) and Magnetic powder (I) 85
Zinc methyl sulfate, zinc methyl sulfonate, zinc-P-dodecylbenzenesulfonate, zinc dinonyl-dithiocarbamate or zinc mercaptobenzothiazole as compound A, and as a heavy metal deactivator a total of 100 parts by weight consisting of % by weight. N,
N'-bis[2-(3-(3,5-di-7-butyl-4
-Hydroxyphenyl)propionyloxy]ethyl]
Oxamide, tris[2-t-butyl-4-thio(2'
-Methyl-42-hydroxy-5'-t-butylphenyl)-5-methylphenyl]phosphite, N, N'
-Bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, oxalic acid-bis(benzylidenehydrazide), 3.9-
Bis[2-(3,5-diamino-2,4,6-)riazaphenyl)ethyl]-2.4,8.10-tetraoxaspiro[5,5]undecane or 2,4,6-triamino-1 , 3゜Prescribed amounts of 5-triazine and other additives were placed in a Hensel mixer (trade name) at the mixing ratios listed in Table 1 below, and after stirring and mixing for 3 minutes, twin screw extrusion with a diameter of 30+ om was carried out. The mixture was melted and kneaded in a machine at 250°C to form pellets. Also, as Comparative Examples 1 to 8, M
Unstabilized powdered crystalline ethylene-propylene block copolymer (ethylene content 8.5% by weight) with FR of 30g/10min 15% by weight and magnetic powder (1% by weight)
) and 85% by weight in total, 100 parts by weight were subjected to melt mixing treatment according to Examples 1 to 12 described later to obtain pellets.

The test pieces used in the oven life test were prepared by injection molding the obtained pellets at a resin temperature of 250°C and a mold temperature of 50°C.

Using the obtained test piece, long-term thermal stability was evaluated by the test method described above. These results are shown in Table 1.

Examples 13-24, Comparative Examples 9-16 Unstabilized powdery crystalline propylene homopolymer 4 with MFR20g/10min as polyolefin
Weight%, MI (discharge amount of molten resin in 10 minutes when applying a load of 2.16 kg at 190°C) 5-0 g/
10 min unstabilized powder Ziegler-Natsuta high density ethylene homopolymer 0.5% by weight, unstabilized powder amorphous ethylene-propylene with Mooney viscosity M L 1+4 (100°C) 25 Zinc stearyl sulfate, zinc stearyl sulfonate, zinc- P-phenol sulfonate, zinc di-n-butyrodithiocarbamate or zinc whaleuryl-dithiocarbamate, N,N'-bis[2-(3
-(3,5-di-butyl-4-hydroxyphenyl)propionyloxy]ethylcoxamide, tris[
2-Butyl-4-thio(2'-methyl-4'-hydroxy-5'-7-butylphenyl)-5-methylphenylphosphite, N,N'-bis[3- (3.5
-dibutyl-4-hydroxyphenyl)propionyl]hydrazine, oxalic acid-bis(benzylidenehydrazide), 3,9-bis[2- (3.5
-diamino-2,4.6-)riazaphenyl)ethyl] -2.4,8.10-tetraoxaspiro[5,5
] Undecane or Banyo 2,4.6-triamino-1,
3.5-) Put the predetermined amounts of riazine and other additives into a Hensel mixer (trade name) at the mixing ratios listed in Table 2 below, stir and mix for 3 minutes, and then
The mixture was melt mixed at 250° C. in a 0r @ twin-screw extruder and pelletized. In addition, as Comparative Examples 9 to 16, MFR is 20
g/10 minutes stabilized unheated powdered crystalline propylene homopolymer 4% by weight, MI stabilized at 5.0 g/10 minutes Coalescence 0.5% by weight, Mooney viscosity M
Unstabilized powdery non-grade ethylene-propylene random copolymer with L 1+4 (100°C) of 25 (
To a total of 100 parts by weight consisting of 0.5% by weight (propylene content 25% by weight) and 95% by weight of magnetic powder (II), predetermined amounts of each of the additives listed in Table 2 below were blended. Pellets were obtained by melt-kneading according to Examples 13-24.

The test pieces used in the oven life test were prepared by injection molding the obtained pellets at a resin temperature of 250°C and a mold temperature of 50°C.

Using the obtained test piece, long-term thermal stability was evaluated by the test method described above. These results are shown in Table 2.

Examples 25-36, Comparative Examples 17-24 Unstabilized powdery crystalline ethylene-propylene block copolymer (ethylene content 12.0% by weight) with M F R 4.0 g7 10 min as polyolefin
18 wt%, MFR 7.0 g/10 min unstabilized powdered crystalline ethylene-propylene random coelectrolyte (ethylene content 2.4 wt%) 2 wt% and magnetic powder (m) A total of 10 consisting of 80% by weight
0! Zinc montanyl sulfate, zinc montanyl sulfonate, zinc dimethyl-dithiocarbamate, zinc diethyl-dithiocarbamate or zinc ethyl-phenyl-dithiocarbamate NJ-bis[2- (3- (3) .5-di-butyl-4-hydroxyphenyl)propionyloxy]ethylcoxamide, tris[2-7-butyl-4-thio(2'-methyl-4'-hydroxy-5'-7-butylphenyl) -5-methylphenyl]phosphite, N
, N'-bis[3-(3,5-di-butyl-4-hydroxyphenyl)propionyl]hydrazine, oxalic acid-bis(benzylidene hydrazide),
3,9-bis[2-(3.5-diamino-2,4.6
-triazaphenyl)ethyl]-2.

4,8.10-tetraoxaspiro[5.5]undecane or 2,4.6-)riamino-1.3.5-)
Hensel mixer (trade name) using the prescribed amounts of riazine and other additives at the mixing ratios listed in Table 3 below.
After stirring and mixing for 3 minutes, the mixture was melt-kneaded at 250° C. in a twin-screw extruder with a diameter of 30 to form pellets. Also, as Comparative Examples 17 to 24, MFR is 4.0g710
unstabilized powdered crystalline ethylene-propylene block copolymer (ethylene content 12.0% by weight)
) 18% by weight, 2% by weight of unstabilized powdered crystalline ethylene-propylene random copolymer (ethylene content 2.4% by weight) with MFR of 1-Og/10 minutes and magnetic powder (III ) 80% by weight in total, and predetermined amounts of each of the additives listed in Table 3 below were blended, and the mixture was subjected to melt mixing treatment according to Examples 25 to 36 to obtain pellets.

The test pieces used in the oven life test were prepared by injection molding the obtained pellets at a resin temperature of 250°C and a mold temperature of 50°C.

Using the obtained test piece, long-term thermal stability was evaluated by the test method described above. These results are shown in Table 3.

The compounds and additives related to the present invention shown in Tables 1 to 3 are as follows.

Compound A [I Coni Compound A [If] : Compound A [m Coni Compound A [IV] : Compound A [V] Nido Compound A [VI Co: To Compound A [■] : Phonate Compound A [■] Neat Compound A [IX] Neat compound A [X] Neat compound A [XI]: Bamate compound A [Xn]: Zinc methyl sulfate Zinc stearyl sulfate Zinc montanyl sulfate Zinc methyl sulfonate Zinc stearyl sulfate Tonk montanyl sulfone Zinc-P-dodecylbenzenesulzinc-p-phenolsulfonezin-dimethyl-dithiocarbamedizinc-diethyl-dithiocarbamedzin-di-n-butyl-dithiocardicin-dinonyl-dithiocarbuff compound A [XIII]: Zinc-di Lauryl-dithiocarbamate compound A [XIV]: Zinc ethyl-phenyl-dithiocarbamate compound A [XV]: Zinc mercaptobenzothiazole heavy metal deactivator [Eco: N,N'-bis[2-(3
-(3,5-di-butyl-4-hydroxyphenyl)propionyloxy]ethyl cooxamide heavy metal deactivator [■Conitris[2-L-butyl-
4thio(2ξmethyl-45-hydroxy-5'-L-butylphenyl)-5-methylphenyl]phosphite heavy metal deactivator [nI]: N,N'-bis[3-
(3,5-di-butyl-4-hydroxyphenyl)
Probionylcohydrazine Heavy metal deactivator [■] Conixalic acid bis(benzylidene hydrazide) Heavy metal deactivator [Vconi 3,9-bis[2-(3,5
-diamino-2,4,6-)riazaphenyl)ethyl]
-2゜4.8.10-Tetraoxaspiro[5,5]undecane Heavy metal deactivator [VI]: 2,4.6-
) Riamino-1,3゜5-triazine phenolic antioxidant 1: 2,8-di-L-butyl-p-cresol phenolic antioxidant 2: Tetrakis[methylene-3
-(3',5'-di-L-butyl-4'-hydroxyphenyl)propionate comethane phenolic antioxidant 3:3,9-bis[1,1-dimethyl-2-(β-(3-t -butyl-4-hydroxy-5-methylphenyl)propionyloxy)ethyl]
-2.4,8.10-Tetraoxaspiro[5,5]undecanephenolic antioxidant 4:2,2-bis[4-[2-
(3,5-di-butyl-4-hydroxyphenylpropionyloxy)ethoxy]phenyl]propanethioether antioxidant 1. Dimyristylthiodipropionate thioether antioxidant 2: distearylthiodipropionate-tetrakis ( 3-Laurylthiopropionate) Phosphorous antioxidant 1: Bis(2,4-di-t-butylphenyl)-hentaerythritol diphosphite Phosphorus antioxidant 2: Bis(2,6-di-t-butylphenyl)-hentaerythritol diphosphite Monobutyl-4-methylphenyl)-pentaerythritol-siphosphite phosphorus antioxidant 3: Tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene-diphosphonite radical generator: 1,3-bis(butylperoxyisopropyl)benzene sulfur-containing zinc compound 1: Zinc sulfide sulfur-containing zinc compound 2: Zinc sulfate sulfur-containing zinc compound 3 Nishin-2-mercaptobenzimidazole metal salt of organic sulfur compound 1: Sodium dimethyl-dithiocarbamate thioether antioxidant 3: Pentaerythritometallic salt of organic sulfur compound 2: Potassium dimethyl-dithiocarbamate metal salt of organic sulfur compound 3: Nickel di-n-butyldithiocarbamate metal salt of organic sulfur compound@ 4: Sodium Mercaptobenzothiazole Ca-8t Calcium Nistearate The Examples and Comparative Examples listed in Table 1 are cases where a crystalline ethylene-propylene block copolymer and magnetic powder (1) were used as the polyolefin. As can be seen from Table 1, Examples 1 to 12 contain a crystalline ethylene-propylene block copolymer, magnetic powder (1), and compound A.
and a heavy metal deactivator, Examples 1 to 12 and Comparative Examples 1 to 8 (Compound A was used instead of Compound A).
When compared with other sulfur-containing zinc compounds, organic sulfur compounds containing metal salts other than zinc or calcium stearate, Examples 1 to 12 had significantly superior long-term thermal stability. It can be seen that a remarkable synergistic effect is observed by blending the two. In other words, it is clear that the comparisons containing sulfur-containing zinc compounds other than Compound A of the present invention, metal salts other than zinc of organic sulfur compounds, or calcium stearate do not exhibit the effects of the present invention. There is nothing described in the above-mentioned Japanese Patent Application Laid-Open No. 169858/1983. In other words, the long-term thermal stability obtained in the present invention is due to a unique characteristic that can only be seen when Compound A is used in combination with a plastic magnet composition formed by blending a magnetic powder and a heavy metal deactivator with a polyolefin in the present invention. This can be said to be effective.

Table 2 shows the mixture of crystalline propylene homopolymer, Ziegler-Natsuta high-density ethylene homopolymer, non-grade ethylene-propylene random copolymer, and magnetic powder (II) as polyolefins; A mixture of a crystalline ethylene-propylene block copolymer and a crystalline ethylene-propylene random copolymer and magnetic powder (m) were used as the polyolefin, and the same effects as described above were confirmed for these as well.

[Effects of the Invention] Compared to conventionally known plastic magnet compositions with improved long-term thermal stability, the composition of the present invention has (1) significantly improved long-term thermal stability of the molded article when made into a molded article; Are better. (2) It has extremely excellent long-term thermal stability, so it is used for plastic magnets that require long-term thermal stability (
For example, it can be suitably used in small generators, small precision motors, rotation control devices for VTRs, tape recorders, etc.).

I”d -40=

Claims (2)

[Claims] (1) Based on 100 parts by weight of a composition consisting of 5 to 20% by weight of polyolefin and 80 to 95% by weight of magnetic powder, a zinc salt selected from zinc alkyl sulfate, zinc sulfonate, zinc dithiocarbamate, and mercaptobenzothiazole is added. A plastic magnet composition comprising 0.01 to 5 parts by weight of one or more organic sulfur compounds (hereinafter referred to as compound A) and a heavy metal deactivator. (2) Phenolic antioxidant, polyolefin 5~
2. The plastic magnet composition according to claim 1, wherein the plastic magnet composition is blended in an amount of 0.05 to 5 parts by weight per 100 parts by weight of a composition comprising 20% by weight and 80 to 95% by weight of magnetic powder.