JPH04233960A - 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 a lead compound and 2-5 pts.wt. of a hydrotalcite stone group, and (E) 0.5-4 pts.wt. of an epoxy resin or epoxy 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, and flexibility.

0002

[Prior Art] Chlorinated polyethylene is a high-strength polymeric material that can be highly filled. Taking advantage of its own advantages (weather resistance, chemical resistance, etc.), chlorinated polyethylene can be used with fillers such as clay and talc. Mixed floor tiles and even metal powders such as ferrite powder are mixed into rubber magnets, etc., which have been put to practical use. However, when producing rubber magnets by adding ferrites to chlorinated polyethylene, there is a problem in that the composition itself is likely to undergo thermal deterioration due to intense heat generation during kneading. For the purpose of improving this, compositions in which stabilizers such as epoxy compounds, stearic acid metal salts, phenol compounds, etc. are added are known (Japanese Patent Publication No. 12860/1983, 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 is free from the above problems, that is, has good oil resistance, excellent thermal stability, and good heat resistance and flexibility.

[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 7 parts by weight of a lead compound and 2 to 5 parts by weight of hydrotalcite stones, (E) 0.0 to 100 parts by weight of an epoxy resin or compound. A chlorinated polyethylene composition containing 5 to 4 parts by weight, wherein the proportion of component (B) in the total amount of components (A) and (B) is 10 to 50% by weight. It is something that provides something. 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
) is preferably 40 or more and has a high molecular weight. 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) Lead compound, hydrotalcite group Also, the lead compound used in the present invention is a lead oxide,
and basic salts of lead and their coprecipitation with silica gel. A typical example of a lead compound is lead monoxide (Pb
O), 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 0.5 to 300 μm, and 0.5 to 300 μm.
5 to 200 μm is preferable, especially 1.0 to 150 μm.
Preferably, the thickness is μm.

Furthermore, the hydrotalcite stone group used in the present invention has a general formula of MgaMeb(OH)cC
O3 ・MH2 O (where Me is Al, Cr or Fe, a is 1 to 10, b is 1 to 5,
c is 10-20, M is 1-8). The average grain size of this hydrotalcite stone group is generally 0.
．． 1 to 150 μm, especially 0.5 to 100 μm
Preferably. Further, it is preferable that Me in the above general formula is Al.

(E) Epoxy resin or compound further,
The epoxy resin or compound used in the present invention has two or more reactive α-epoxy groups in one molecule, and can be cured with a curing agent. These resins are currently widely used as adhesives, coating materials, cast products, and molded products, and their molecular weights are usually 300 to 6,000 (preferably 300 to 50).
00).

Typical examples of this epoxy resin include epichlorohydrin, phenolic -OH, and carboxylic acid -OH.
Preference is given to those obtained by reaction of COOH and amines with active hydrogen compounds having active hydrogen, such as -NH2. The most common epoxy resins such as Epicote and Epon Araldite contain bisphenol A (
The epoxy resin obtained by reacting 4,4'-dioxydiphenylpropane with epichlorohydrin is most suitable. Additionally, commonly manufactured materials can also be used. Typical examples are glycidyl ethers of dihydric phenols and glycidyl ethers of bisphenols (e.g., those mainly composed of diphenolic acid, those mainly composed of bisphenol A and p-xylene dichloride condensate).
, glycidyl ethers of polyphenols, glycidyl ethers of aliphatic and other dialcohols and trial alcohols, and glycidyl ethers of amines or amides. These epoxy resins were developed by Shunsuke Murahashi, Ryohei Oda,
Edited by Minoru Imoto, “Plastic Handbook” (Asakura Shoten,
(Published in 1981), pages 272 to 277, the manufacturing method, types, etc. are described in detail.

(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 it exceeds 500 parts by weight, it will not be possible to achieve a high ferrite loading by rolling or kneading, making kneading difficult. The amount of the lead compound 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 the lead compound 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 stability will not be further improved. Regarding hydrotalcite stones, the amount is 2 to 5 parts by weight, preferably 2.5 to 5 parts by weight, particularly 3 to 5 parts by weight.
Parts by weight are preferred. If the composition ratio of the hydrotalcite group is less than 2 parts by weight, a composition with good stability cannot be obtained. On the other hand, even if it is blended in an amount exceeding 5 parts by weight, the stability will not be further improved and, in fact, it may bleed onto the surface of the molded product, which is not preferable. Further, in the case of an epoxy resin or compound, the amount is 0.5 to 4 parts by weight, preferably 1 to 4 parts by weight, and particularly preferably 1 to 3 parts by weight. If the composition ratio of the epoxy resin is less than 0.5 parts by weight, a composition with good processability, thermal stability and light stability cannot be obtained. On the other hand, even if more than 4 parts by weight is blended, although the thermal stability and light stability are slightly improved, kneading becomes difficult in terms of processability (workability).

(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. Additives such as plasticizers, oxygen, ozone, heat and light (ultraviolet) stabilizers, lubricants and tackifiers may be added depending on the intended use of the composition.

[0018] 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, or 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 used by molding it 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.

[0020]

[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

[0021] 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. Furthermore, the oil resistance test was conducted using a 2mm sheet with a width of 20mm and a length of 20mm.
After creating the oil, rubber swelling oil No. No. 1 and rubber swelling oil No. After being immersed in each oil using No. 3 at a temperature of 120°C and an aging time of 24 hours, the volume change rate (%) (hereinafter referred to as "ΔV") was determined. In addition, the physical properties and types of chlorinated polyethylene, NBR (acrylonitrile-butadiene copolymer rubber), magnetic powder, lead compound, hydrotalcite group, epoxy resin or compound, and other additives used in the Examples and Comparative Examples 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"). [(C) Magnetic powder] The magnetic powder has a major axis diameter of 1 μm,
Strontium ferrite powder (I
HC=3500 Oe) (hereinafter referred to as “Sr・F”)
). [Lead compound] As a lead compound, tribasic lead nitrate (average particle size 1 μm, manufactured by Kosei Co., Ltd., hereinafter referred to as "TS")
was used. [Hydrotalcite stone group] The hydrotalcite stone group includes hydrotalcite with an average particle size of 1 micron (manufactured by Kyowa Kagaku Co., Ltd., trade name DHT-4A, specific surface area 10
m2/g, hereinafter referred to as "DHT") was used. [Epoxy resin or compound] As the epoxy resin or compound, an epoxy resin (manufactured by Shell Chemical Co., Ltd., Epicoat #828, hereinafter referred to as "#828") was used. Examples 1 to 3, Comparative Examples 1 to 5 Chlorinated polyethylene (CPE), acrylonitrile-butadiene copolymer rubber (NBR), magnetic powder, lead compound, hydrotalcite, the amounts of which are shown in Table 1. The stones and the epoxy resin or compound were thoroughly kneaded using an open roll whose surface temperature was set in advance to 100°C. After kneading, a 2 mm sheet was created using the same roll.

Each sheet thus obtained was subjected to a bending test, a thermal stability test, a heat aging resistance test, and an oil resistance test. 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 lead compound and 2 to 5 parts by weight of hydrotalcite group, (E) 0 epoxy resin or compound A composition comprising .5 to 4 parts by weight of (A
A chlorinated polyethylene composition in which the proportion of component (B) in the total amount of component () and component (B) is 10 to 50% by weight.