JPH0764965B2 - Nitrile polymer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a nitrile polymer composition. More specifically, it relates to a nitrile polymer composition in which metal powder is uniformly dispersed.

[Conventional technology]

Various polymer materials and metals are combined to make conductive resin,
Although it is being considered to be used as a metal reinforcing material, etc., polymer materials and metals generally have poor adhesive properties, so simply mixing the two together cannot achieve the reinforcing purpose, but rather reduces the strength. Since the change in physical properties (fatigue) and the like during use can be observed, the metal used is often subjected to a surface treatment before use.

[Problems to be solved by the invention]

The present inventors have studied to obtain a composition in which, when the nitrile polymer and the metal powder are compounded, the both are uniformly and stably interdispersed with each other to improve fatigue properties and the like.

Therefore, the fact that the nitrile group contained in the nitrile polymer forms a stable coordination compound with the metal [Disc
ussions Faraday Soc. 16: 210 (1954), J. Chem.
Soc. 123, 2901 (1923)], sulfur is allowed to coexist therewith to form a sulfide of a specific metal to obtain the desired composite composition for the above purpose. I found that

[Means for Solving Problems] and [Action] Accordingly, the present invention relates to a nitrile polymer composition, which is a nitrile polymer which is a homopolymer or copolymer of acrylonitrile or methacrylonitrile. Coalescing,
It consists of a mixture of metal powder having d electrons and sulfur.

As the nitrile polymer, a homopolymer of acrylonitrile or methacrylonitrile or a copolymer obtained by copolymerizing 5% by mol or more thereof is used. As the comonomer forming the copolymer, for example, butadiene, Isoprene,
At least one of chloroprene, acrylamide, styrene, vinyl ethyl ether, vinyl acetate, maleic anhydride, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate and the like can be mentioned. Further, hydrogenated rubber or the like in which unsaturated bonds are reduced by hydrogenating the double bonds of a diene-based copolymer such as acrylonitrile-butadiene copolymer can also be used as the nitrile-based polymer.

The reason why the metal powder having d-electrons is used is that it is easy to form a ligand, and specific examples thereof include powdery copper, zinc, nickel, cadmium, silver, and a copper-zinc alloy. In particular, copper powder and copper-zinc alloy powder are preferably used.

These metal powders contain about 2-90% of the essential components including sulfur.
The sulfur is used in such a proportion that it accounts for wt%, and the sulfur is used in a proportion of about 0.5 to 60 wt% with respect to the metal powder. As will be described later, the range of the metal powder content is mainly determined in relation to the application, and sulfur is added in addition to the amount necessary for forming a thin film of sulfide on the surface of the metal powder particles. When sulfurization is required, it is used in such an amount that a small amount of unreacted sulfur remains.

The composition is prepared by a solution method or a melting method.

In the case of the solution method, first the nitrile polymer is treated with its solvent, for example, in the case of polyacrylonitrile, sulfones, dimethyl sulfoxide, dimethylformamide,
Dimethylmethoxyacetamide, ethylene cyanohydrin, hydroxyacetonitrile, γ-butyrolactone, etc., and in the case of acrylonitrile-butadiene copolymer (nitrile rubber), dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, etc., Depending on the degree of polymerization of the polymer, it is generally about 5
Dissolve at a concentration of 40% by weight. If it is less than this, the productivity becomes low, while if it is more than this, the viscosity becomes high,
It becomes difficult to mix.

In the solution of the nitrile polymer thus prepared,
Metal powder and sulfur are added and mixed for a predetermined time at room temperature or below the boiling point of the solvent. The rate of complex formation is
As with normal chemical reactions, the higher the temperature, the faster it becomes. Then, as the formation of the complex progresses, the production of a black floating substance comes to be recognized.

The melting method is applied to an acrylonitrile-conjugated diene copolymer in a rubber state even at room temperature, polyacrylonitrile having a glass transition temperature of 200 ° C. or lower, or a solvent swelled to lower the softening temperature. Specifically, it is carried out by adding metal powder and sulfur to a molten nitrile polymer by using a closed kneader such as a roll, a Banbury mixer, or a kneader, and mixing by a method similar to rubber kneading. .

With the passage of mixing time, for example, in the case of copper, the color changes to black indicating the formation of copper sulfide. After performing a mixing operation for an appropriate time, when the nitrile polymer used is immersed in a solvent, a gelled product showing the formation of a complex of the polymer and the metal becomes dispersed in the liquid.

The complex is formed by such a method because a metal such as copper forms a sulfide near its surface, that is, a metal such as copper is sulfurized to form a thin film of a sulfide such as copper sulfide on the surface. It is considered that the formed sulfide is bonded to the nitrile group of the nitrile polymer by a stable coordination bond. This is supported by the fact that in the case of ethylene-propylene copolymers or polyethyl acrylates that do not contain nitrile groups, no complex can be obtained by the same treatment with copper powder and sulfur.

The structure of this bonding method is similar to the carbon gel formed between rubber and carbon black. That is, when carbon black is mixed with rubber, a part of the rubber chemically bonds to the carbon surface to form a gel. When the rubber in such a state is dissolved in the solvent, the carbon black having a large specific gravity should precipitate, but the carbon black floats in the liquid without precipitation.

In the same manner, in the present invention, a composite that can be called a kind of metal gel is formed.

〔The invention's effect〕

The nitrile polymer composition according to the present invention is provided as a composition in which metal powder is uniformly and stably dispersed by directly binding a metal to a nitrile polymer via sulfur to form a composite.

Therefore, such a nitrile polymer composition is used for the following purposes depending on the content of the metal powder contained in the composition by effectively utilizing such characteristics.

Metal powder content 2 to 30% by weight: Reinforcing property is provided and mainly used to increase elastic modulus or as a vibration absorber.

Metal powder content 10-60% by weight: Since metal powders come into partial contact with each other and conductivity is improved, antistatic paints and resins that use electrical characteristics, electromagnetic shielding materials, low noise sealing materials, Used as pressure sensitive conductive rubber.

Metal powder content 60 to 90% by weight: Contact between metal powders considerably occurs, the role of the nitrile polymer in the composition in this range becomes a binder, and the properties of the entire composition become metallic. Therefore, conductivity and thermal conductivity will be imparted to the polymer material, and mainly conductive paint (conductor), conductive adhesive, conductive sliding component material, good thermal conductive sliding component material, etc. It can be mentioned as an application.

〔Example〕

 Next, the present invention will be described with reference to examples.

Example 1 Nitrile rubber (Zetpol 2010 manufactured by Nippon Zeon Co., Ltd .; hydrogenated nitrile rubber) was wound around a roll of a roll mill, and copper powder having an average particle diameter of 10 μm was gradually added thereto at a ratio of 200 parts by weight per 100 parts by weight of rubber and kneaded. To do. When the rubber becomes copper-colored due to the mixing of copper powder, 5 parts by weight of sulfur is added, and roll kneading is continued. With the passage of the kneading time, the color of the rubber changes to black and the formation of copper sulfide becomes visible. After kneading for 30 minutes, the kneaded product was immersed in methyl ethyl ketone which is a solvent for nitrile rubber.

Copper and copper sulfide should be precipitated because their specific gravity is originally higher than the specific gravity of the solvent, but the blackened copper powder does not precipitate and floats in the solvent. This means that the polymer and copper were chemically bound, and the formed complex was dispersed in the liquid and floated due to the molecular motion of the polymer chain.

Elemental analysis of the complex thus formed was performed as follows. The complex methyl ethyl ketone dispersion was placed in a graduated cylinder with a volume of 10 ml and left for 10 hours, then the liquid level height was set to 1 and the bottom sediment position was set to 7.
Positions 2 to 6 at equal intervals are determined, 0.1 ml of the dispersion liquid is sampled from each height position with a microsyringe, and a fluorescent X-ray analyzer (manufactured by Rigaku Denki Kogyo) is used for each fraction.
IKF-3064) was used to quantify copper and sulfur in the complex. The results obtained are shown in the following table.

From this result, it is clear that the composite is a rubber containing copper and sulfur, and it is also clear that the added sulfur is almost bound to the copper surface. Formation was revealed.

Comparative Example In Example 1, when nitrile rubber in which only copper powder was dispersed without adding sulfur was immersed in methyl ethyl ketone, copper powder was deposited on the bottom and re-dispersed in a few seconds. From the weight measurement of this precipitate, 99%
It was found that the copper powder was recovered and almost no rubber was attached.

0.1 of the composites respectively obtained in Example 1 and Comparative Example
When a sample prepared by casting a% methyl ethyl ketone solution is observed by a transmission electron micrograph, rubber is bonded between the copper powder and the copper powder in Example 1 to form a chain. In the comparative example, the copper powders were present in different pieces.

Example 2 In Example 1, instead of copper powder, average diameter 15 μm, length
The same amount of 56 μm copper fiber powder was used. That is, nitrile rubber (Zetpol 2010) was wound around a 10-inch open roll, and copper fiber powder was gradually added thereto at a ratio of 200 parts by weight per 100 parts by weight of the rubber and kneaded.
Parts by weight of sulfur were added and roll kneading continued for 20 minutes. In this case, when the kneaded product was immersed in methyl ethyl ketone, it did not float in methyl ethyl ketone because the copper fiber powder was heavy, and it settled, so the result of measuring the weight of the precipitate was
From the weight increase of the copper fiber powder, it was found that 12% of the nitrile rubber was bound to the copper fiber powder.

Example 3 In Example 1, instead of copper powder, copper having an average particle size of 20 μm was used.
The same amount of zinc alloy powder was used. That is, nitrile rubber (Zetp
ol 2010) is wound around a 10 inch open roll and alloy powder is gradually added and kneaded at a ratio of 200 parts by weight per 100 parts by weight of rubber, and when the rubber becomes copper colored, 5 parts by weight of sulfur is added, Roll kneading was continued for 20 minutes. In this case,
When the kneaded product was immersed in methyl ethyl ketone, a part of it floated in the methyl ethyl ketone, but most of it precipitated. When the amount of bound rubber of this precipitate was measured in the same manner as in Example 2, it was found that 31% of the nitrile rubber was bound to the alloy powder.

Example 4 A 10 wt% methyl ethyl ketone solution of nitrile rubber (Zetpol 2010) is heated to 70 ° C., 200 g of copper powder and 5 g of sulfur are added thereto, and the mixture is stirred. After mixing, the color of the liquid gradually changes to black, and it can be seen that copper and sulfur react with each other. When stirring was stopped after stirring for 60 minutes, most of the copper powder was floating.

Example 5 Polyacrylonitrile Strand (Mitsui Toatsu Product BAREX
E) 50 g of dimethylformamide was dissolved in 450 g, and while maintaining the temperature of the solution at 90 ° C., the average particle size was 10 μm with stirring.
100 g of copper powder and 3 g of sulfur were added. After the addition, the mixture was stirred for 60 minutes, and when the stirring was stopped, blackened copper powder was precipitated. When the amount of bound rubber of this precipitate was measured in the same manner as in Example 2, it was found that 26% of polyacrylonitrile was bound to the copper powder.

Claims (1)

[Claims] 1. A mixture of a nitrile polymer which is a homopolymer or a copolymer of acrylonitrile or methacrylonitrile, a metal powder having d electrons and sulfur, wherein the metal powder accounts for 2 to 90% by weight of the mixture. A nitrile polymer composition in which sulfur is used in a proportion of 0.5 to 60% by weight with respect to the metal powder, and the balance is a nitrile polymer.