JPH04233961A - Chlorinated polyethylene composition - Google Patents

Abstract

PURPOSE:To provide the title composition, a magnetic rubber composition excellent in heat and oil resistance, thermal stability and flexibility, esp. suitable for small-sized motors such as for OA equipment and home electrical appliances or as a flexible magnetic material. CONSTITUTION:The objective composition can be obtained by incorporating a total of 100 pts.wt. of (A) 50-90wt.% of a chlorinated polyethylene and (B) 10-50wt.% of an acrylonitrile-butadiene copolymer rubber >=30wt.% in nitrile content with (C) 800-1500 pts.wt. of magnetic powder made up of barium ferrite and/or strontium ferrite, (D) 3-7 pts.wt. of magnesium oxide and 2-5 pts.wt. of a lead compound, and (E) 1-3 pts.wt. of a bisamide compound and 1-5 pts.wt. of a pentaerythritol compound.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic rubber composition made of chlorinated polyethylene that has excellent thermal stability, oil resistance, heat resistance, processability, and flexibility.

0002

[Prior Art] Chlorinated polyethylene is a high-strength polymeric material that can be highly filled and mixed with fillers such as clay and talc to take advantage of its own advantages such as weather resistance and chemical resistance. It is used in rubber magnets, etc., mixed with metal powder such as ferrite powder. However, when producing rubber magnets by adding ferrites to chlorinated polyethylene, there is a problem in that the composition itself is likely to be thermally deteriorated due to the intense heat generation during kneading. In order to improve this, a method of adding stabilizers such as epoxy compounds, stearic acid metal salts, phenolic compounds, etc. has been proposed (Japanese Patent Publication No. 12860/1982, Japanese Patent Application Laid-open No. 116647/1983).

In recent years, anisotropic rubber magnets with high magnetic properties have been developed, and acrylonitrile crosslinked by adding sulfur or sulfur compounds is used in fields where oil resistance is required, such as in small motors. Butadiene copolymer rubber (hereinafter referred to as NBR) is used.

0004

[Problem to be solved by the invention] However, NBR
has the disadvantage that it requires a crosslinking process, which increases costs, and it is difficult to recycle. On the other hand, chlorinated polyethylene has a problem of poor oil resistance and cannot be said to have sufficient heat resistance.

[0005] From the above, the present invention solves these drawbacks (
The object of the present invention is to obtain a chlorinated polyethylene composition which has good oil resistance, excellent heat resistance, thermal stability, flexibility, and processability.

[0006]

[Means for Solving the Problems] The present invention provides that (A) chlorinated polyethylene and (B) acrylonitrile-butadiene copolymer rubber having a nitrile content of 30% by weight or more are added to 100 parts by weight in total. C) 800 to 1500 parts by weight of magnetic powder consisting of barium ferrite and/or strontium ferrite, (D) 3 to 1500 parts by weight of magnesium oxide
7 parts by weight, 2 to 5 parts by weight of a lead compound, 1 to 3 parts by weight of (E) a bisamide compound, and 1 to 5 parts by weight of a pentaerythritol compound,
The present invention provides a chlorinated polyethylene composition in which the proportion of component (B) in the total amount of components (A) and (B) is 10 to 50% by weight. The present invention will be specifically explained below.

(A) Chlorinated polyethylene The chlorinated polyethylene used in the present invention can be obtained by chlorinating polyethylene powder or particles in an aqueous suspension or by chlorinating polyethylene dissolved in an organic solvent. (preferably by chlorination in aqueous suspension). Generally, amorphous or crystalline chlorinated polyethylene with a chlorine content of 20 to 50% by weight is used, and amorphous chlorinated polyethylene with a chlorine content of 25 to 45% by weight is particularly preferred.

The polyethylene is prepared by homopolymerizing ethylene or by combining ethylene with at most 10% by weight of α-olefin (
In general, it is obtained by copolymerizing carbon atoms (having at most 12 carbon atoms). Its density is generally
It is 0.910 to 0.970 g/cm3. Moreover, its molecular weight is 50,000 to 700,000.

(B) Acrylonitrile-butadiene copolymer rubber (NBR) NBR used in the present invention is a copolymer rubber obtained by copolymerizing acrylonitrile and butadiene, and its Mooney viscosity (ML1+4, 100°C
) preferably has a high molecular weight of 40 or more. Also,
The acrylonitrile content is at least 30% by weight, preferably at least 35%. Acrylonitrile content is 30
If it is less than % by weight, oil resistance will deteriorate, which is not preferable.

(C) Magnetic Powder Typical examples of magnetic powder used in the present invention include iron oxide (Fe2O3) and barium carbonate (BaCO3).
3) Barium ferrite (BaO.6
), iron oxide and strontium carbonate (Sr
Examples include strontium ferrite (SrO.6Fe2 O3) made from carbon dioxide (CO3) and flat ferrite made from iron hydroxide. These magnetic powders have a hexagonal crystal structure,
It is characterized by having an isotropic direction and an anisotropic direction. In the present invention, it is desirable to have these characteristics, and the true density is generally 5.0 to 5.5 g/cm.
3, and particularly preferably 5.2 to 5.3 g/cm3. Further, depending on the resistance, the magnetic powder particles preferably have a particle size of 0.8 to 3.0 microns, particularly preferably 1.8 to 2.3 microns. Furthermore, depending on the purpose of use, it may be treated with a titanate coupling agent.

(D) Magnesium oxide, lead compound and
The magnesium oxide used in the present invention has a 100 mesh pass and a specific surface area of 150 m2/g. The lead compound is also selected from oxides of lead and basic salts of lead and their co-precipitation with silica gel. Typical examples of lead compounds include lead monoxide (PbO), red lead (trilead tetroxide,
Pb3O4), etc. Further, examples of the basic salt of lead include basic lead silicate and tribasic lead sulfate. Furthermore, the proportion of silica gel in the coprecipitate of lead basic salt and silica gel is usually 10 to 60% by weight (preferably 10 to 50% by weight, preferably 20 to 50% by weight).
). The average particle size of these lead compounds is generally 0.
The thickness is 5 to 300 μm, preferably 0.5 to 200 μm, and particularly preferably 1.0 to 150 μm.

(E) Bisamide compound, pentaerythritol compound The bisamide compound used in the present invention is a compound represented by RCONH2, and has a melting point of 50
~150°C, and representative examples thereof include stearylamide, pathymicylamide, oleylamide, methylenebis-stearamide, ethylenebis-stearamide, stearamide, and erucylamide. The pentaerythritol compound has a specific gravity of 0.80 to 1.10 and a melting point of 40°C or higher. Typical examples include dipentaerythritol, dipentaerythritol ester, pentaerythritol fatty acid ester, pentaerythritol tetrafatty acid ester, and the like.

(F) Composition ratio (mixing ratio) The ratio of NBR in the total amount of chlorinated polyethylene and NBR is 1.
0 to 50% by weight, preferably 15 to 50% by weight,
Particularly suitable is 15 to 45% by weight. If the composition ratio of NBR is less than 10% by weight, oil resistance will be poor. On the other hand, if it exceeds 50% by weight, the heat resistance and flexibility of the resulting product will be poor. The blending ratios (composition ratios) of other compositional components to 100 parts by weight of the total amount of chlorinated polyethylene and NBR are as follows.

The amount of magnetic powder is 800 to 1,500 parts by weight, preferably 850 to 1,500 parts by weight, particularly 87 to 1,500 parts by weight.
0 to 1500 parts by weight is suitable. If the amount of magnetic powder is less than 800 parts by weight, a product with excellent magnetic force cannot be obtained. On the other hand 1
If more than 500 parts by weight is blended, it will not be possible to fill the ferrite to a high level in rolling operations, kneading operations, etc., making kneading operations difficult. Further, the amount of magnesium oxide is 3 to 7 parts by weight, preferably 3 to 6 parts by weight, and particularly preferably 3 to 5 parts by weight. If the composition ratio of magnesium oxide is less than 3 parts by weight, a composition with good thermal stability cannot be obtained. On the other hand, even if the amount exceeds 7 parts by weight, the thermal stability will not be further improved. Further, the lead compound is 2 to 5 parts by weight,
The amount is preferably 2.5 to 5 parts by weight, particularly preferably 3 to 5 parts by weight. If the composition ratio of the lead compound is less than 2 parts by weight, thermal stability will decrease. On the other hand, even if the amount exceeds 5 parts by weight, the thermal stability will not be further improved. The amount of the bisamide compound is 1 to 3 parts by weight, preferably 1.5 to 3 parts by weight, and particularly preferably 2 to 3 parts by weight. If the composition ratio of the bismaleimide compound is less than 1 part by weight, the surface of the obtained product cannot be cleaned and the processability is poor. On the other hand, if it is blended in an amount exceeding 3 parts by weight, it bleeds out onto the surface of the product, making it impossible to obtain a good product. Further, the amount of the pentaerythritol compound is 1 to 5 parts by weight, preferably 2 to 5 parts by weight, and particularly preferably 3 to 4 parts by weight. The composition ratio of pentaerythritol compounds is 1
If it is less than 1 part by weight, the processability to obtain a product will be poor. On the other hand 5
Even if it is blended in excess of parts by weight, it bleeds out onto the surface of the product, making it impossible to obtain a good product.

(G) Mixing method, molding method, etc. Although the composition of the present invention can be obtained by uniformly blending the above substances, fillers commonly used in the rubber industry and the resin and resin industry may also be used. , plasticizer,
stabilizers against oxygen, ozone, heat and light (ultraviolet),
Additives such as lubricants and tackifiers may be added depending on the intended use of the composition.

[0016] When producing the composition of the present invention, the blending (mixing) method thereof is to mix using a mixer such as an open roll, dry blender, Banbury mixer, and kneader commonly used in the art. Bye. Among these mixing methods, in order to obtain a more uniform composition, two or more of these mixing methods may be applied (for example, after mixing in advance with a dry blender, the mixture may be mixed using an open roll). how to). In producing the composition of the present invention, all the ingredients may be mixed at the same time, but some of the ingredients may be mixed in advance and then other ingredients may be mixed into the resulting mixture ( For example, a method in which chlorinated polyethylene and NBR are mixed in advance and then the resulting mixture is mixed with magnetic powder).

The composition of the present invention can be molded into a desired shape using a molding machine such as an extrusion molding machine, an injection molding machine, a compression molding machine, or a calendar molding machine that is commonly used in the rubber industry. be done.

[0018]

[Examples] The present invention will be explained in more detail with reference to Examples below. In addition, the bending test was conducted with a thickness of 3 mm and a width of 8 m.
m, hold a sheet with a length of 50 mm between calipers, and measure 6 mm.
The rank of cracks on the surface is shown in 3 levels when the appearance of cracks observed with the naked eye according to the following criteria is shown below. Rank Degree of surface cracks○
No cracks at all△
Slight cracks × Large cracks and breakage

In addition, the thermal stability test was conducted by preparing a sheet with a thickness of 2 mm, a width of 20 mm, and a length of 20 mm, and then leaving it in an atmosphere at a temperature of 150° C. for 30 and 60 minutes using a gear aging tester. Thereafter, the surface condition of the sheet was visually observed for the presence or absence of spots. In addition, the heat aging resistance test was performed by punching JIS #3 dumbbells from a 2 mm sheet and testing the samples at 120°C x 2 using a gear aging tester.
After aging for 4 hours, the breaking strength (hereinafter referred to as "TB") and breaking elongation (hereinafter referred to as "EB") were measured using a tensile tester.
) was measured and the rate of change (%) was investigated.

[0020]Furthermore, in the oil resistance test, after creating a 20 mm width and 20 mm length from a 2 mm sheet, JIS K
- Using a test tube aging tester according to 6301,
Regarding the oil, rubber swelling oil No. No. 1 and rubber swelling oil No. No. 3 was immersed in each oil at a temperature of 120°C and an aging time of 24 hours, and the volume change rate (
%) (hereinafter referred to as "ΔV").

Note that the chlorinated polyethylene, NBR (acrylonitrile-butadiene copolymer rubber), magnetic powder, lead compound, hydrotalcite stone group, epoxy resin or compound, and other additives used in the Examples and Comparative Examples The physical properties, types, etc. are shown below. [Chlorinated polyethylene] Ethylene-butene-1 copolymer containing 3.0% by weight of butene-1 (density 0.94
5g/cc, average molecular weight approximately 200,000) in an aqueous suspension to produce amorphous chlorinated polyethylene (chlorine content 41.5% by weight, Mooney viscosity (ML1+4) 1).
No. 20, hereinafter referred to as "CPE") was manufactured. [Acrylonitrile-butadiene copolymer rubber (NBR
)] Mooney viscosity ML1+4 (100°C) is 56, acrylonitrile content is 35% by weight, and specific gravity is 0.9
No. 8 nitrile rubber (JSR manufactured by Japan Synthetic Rubber Co., Ltd.)
N230S1) (hereinafter referred to as "NBR"). [Magnetic powder] As magnetic powder, strontium ferrite powder (IHC=
3500 Oe) (hereinafter referred to as "Sr.F"). [Magnesium oxide] As magnesium oxide, magnesium oxide [manufactured by Kyowa Chemical Industry Co., Ltd., product name Kyowa Mag #
150,100 mesh pass, specific surface area 150m2/
g, hereinafter referred to as "MgO"] was used. [Lead compound] As a lead compound, tribasic lead sulfate [manufactured by Koshosha, trade name Tribase, average particle size 1 μm, hereinafter "TS"
] was used. [Bismaleide Compound] As the bismaleide compound, stearamide [manufactured by Nippon Kasei Co., Ltd., trade name Diamit O-200, melting point 99°C, nitrogen content 4.8% or more, hereinafter referred to as "O-200"] was used. [Pentaerythritol compound] As a pentaerythritol compound, pentaerythritol fatty acid ester [manufactured by Schill, Seilacher, trade name Structol WB212, melting point 45°C, moisture 0.3
Hereinafter referred to as "WB-212"] was used.

Examples 1 to 3, Comparative Examples 1 to 5 Chlorinated polyethylene (hereinafter referred to as CPE), acrylonitrile-butadiene copolymer rubber (NBR), and magnetic powder, the amounts of which are shown in Table 1. , magnesium oxide, a lead compound, a bisamide compound, and a pentaerythritol compound were sufficiently kneaded using an open roll whose surface temperature was set in advance to 100°C. After kneading, 2m
m and 3 mm sheets were created. Using each sheet obtained in this way, a bending test, a thermal stability test, a heat resistance test, and an oil resistance test were conducted. The results are shown in Table 2.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Effects of the Invention] The chlorinated polyethylene composition obtained by the present invention not only has good ferromagnetism, but also exhibits the following effects (characteristics). (1) Excellent heat resistance, thermal stability, and mechanical strength. (2) Excellent oil resistance and dimensional stability. (3) Even if plasticizers, lubricants, etc. are added, these do not bleed. (4) Workability (for example, kneading properties) is excellent despite the large amount of magnetic powder blended. The chlorinated polyethylene composition obtained by the present invention not only has the excellent effects described above, but also has good ferromagnetism, so it can be formed into a rubber magnet and used in the following fields. be able to. (1) Gaskets for refrigerators (2) Magnets for signs (3) Magnets for teaching materials (4) Magnets for electronic equipment (5) Magnets for magnetic sorting machines (6) Magnetic paint

Claims (1)

[Claims] Claim 1: To 100 parts by weight of the total amount of (A) chlorinated polyethylene and (B) acrylonitrile-butadiene copolymer rubber having a nitrile content of 30% by weight or more,
(C) 800 to 1500 parts by weight of magnetic powder consisting of barium ferrite and/or strontium ferrite, (D) 3 to 7 parts by weight of magnesium oxide and 2 to 5 parts by weight of a lead compound, (E) 1 to 3 parts by weight of a bisamide compound. and 1 to 5 parts by weight of a pentaerythritol compound, wherein the proportion of component (B) in the total amount of components (A) and (B) is 10 to 50% by weight. Certain chlorinated polyethylene compositions.