JPS6050383B2 - Conductive urethane rubber composition that can be vulcanized at normal pressure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive urethane rubber composition that can be crosslinked with a peroxide, and particularly to a rubber composition that can be vulcanized at normal pressure (can be vulcanized without pressure and in a hot atmosphere). It is.

Conventionally, urethane rubber that can be crosslinked with peroxides is produced by mixing peroxides such as dialkyl or diacyl, fillers such as carbon black or silica, calcium carbonate, plasticizers, anti-aging agents, etc. in an open roll, Panbury mixer, etc. The kneaded composition is usually vulcanized at 140*C or higher under pressure.

There are two methods of pressurization: pressurization with a press, and pressurization by adding pressurized air into a vulcanization can.Press vulcanization is a method of pressurizing molded products such as rubber plates and packing O-rings in a vulcanization can. Vulcanization is used in the manufacture of hoses. This method is suitable for manufacturing molded products, but when manufacturing hoses, it is necessary to wrap the hose with cloth, rubber, etc., and the length of the hose that can be manufactured is limited to the capacity of the vulcanized can. There are disadvantages such as intermittent manufacturing processes and poor productivity. One possible way to overcome this drawback is to use a method of vulcanization in hot air at normal pressure, which is used to vulcanize silicone rubber, but if this method is applied to urethane rubber, it will result in a porous sponge. I can only get something like this.
Therefore, while researching urethane, the present inventor found that rubber compositions containing conductive carbon black were SRF), SAFN
Compared to rubber compositions containing ordinary fanes blacks such as HAF or FEF or thermal blacks such as MT)FT, there is significantly less foaming in areas that overflow from the mold during molding, that is, areas that are not pressurized. After realizing this, we carefully considered the type of conductive carbon black and the degree of foaming, and found that when conductive carbon black with a specific oil absorption and surface area is blended,
It was discovered that vulcanization can be performed at normal pressure without foaming. However, the tensile strength, elongation,
Although normal pressure vulcanization has the same hardness and good properties as breath vulcanization, when comparing the conductivity, there is a big difference between normal pressure vulcanization and breath vulcanization. Good conductivity cannot be obtained with pressure vulcanization, so it can be used as ordinary urethane rubber, but for things that require conductivity or semi-conductivity such as antistatic properties and electrical connections, atmospheric pressure vulcanization is recommended. things cannot be used. Furthermore, if an attempt is made to blend more than 40 phr of this carbon black in order to improve conductivity, the viscosity of the blend increases and roll kneading becomes impossible.

The present inventors investigated organic titanium compounds having alkoxy residues for the purpose of lowering viscosity, and surprisingly found that they significantly improved conductivity rather than having an effect of lowering viscosity.This led to the completion of the present invention. It was reached.
The purpose of this invention is to eliminate the drawbacks of the prior art described above,
The object of the present invention is to provide a novel urethane rubber composition that can be used as a vulcanized rubber that exhibits good properties without becoming porous and has conductivity in a hot atmosphere at normal pressure. The gist of the invention is that ester-based urethane rubber crosslinkable with peroxide is
A conductive urethane that can be vulcanized at normal pressure and is made by blending conductive carbon black with an oil absorption of 250 m1/100y or more according to No. 4 and a surface area of 500 m1/y or more by nitrogen adsorption method and an organic titanium compound having an alkoxy residue. In rubber compositions.

Moreover, the carbon black is preferably 5 to 35 parts by weight per 1 part by weight of the urethane rubber. Preferably, 0.05 to 5 parts by weight, preferably 0.1 to 4 parts by weight, of the organic titanium compound having an alkoxy residue is blended with 100 parts by weight of the carbon black. .
The reason why the amount of carbon black is limited to 5 to 35 parts by weight in this invention is that if it is less than 5 parts by weight, the vulcanizate becomes porous at normal pressure, and if it is more than 35 parts by weight, it will be open rolled or sealed. This is because when kneading with a type mixer such as a Panbury mixer (trade name of Farrell Birmingham Co., Ltd.), the viscosity of the compound increases, making it difficult to work. The surface area is 500r! The reason why it is set to l/y or more is because if it is smaller than this, foaming will result.

In addition, in this invention, the organic titanium compound is
The reason why it is limited to 5 parts by weight is that if it is less than 0.05 parts by weight, there is no effect of improving conductivity, and if it is more than 5 parts by weight, the effect of improving conductivity is the same as if it is less than that. This is because other characteristics of the product will be lost.

Further, in this invention, examples of organic titanium compounds having an alkoxy residue include isopropyl triisostearoyl titanate, isopropyl tri)todecylbenzene nulphonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, and tetraisopropyl bis(dioctyl phosphate). titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bifu(ditridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, Dioctylpyrophoresphate)
Ethylene titanate” etc. are used.

The conductive urethane rubber composition of the present invention, which can be vulcanized at normal pressure, will be explained in more detail below with reference to some examples.

Examples 1 to 5 As shown in the following table, a mixture of various weight parts of each compounding material was thoroughly kneaded using an open roll, and then an extruder was used to create an inner diameter of 40φ and a thickness of 7WrI! A cylindrical normal-pressure vulcanized tube is extruded and immediately heated to a temperature of 250°C. It has a structure that allows continuous vulcanization.

) to produce a vulcanized hose, cut the vulcanized hose open, and punch it out with a dumbbell-shaped No. 3 punching die to make a sample suitable for the method of JIS K63Ol (test method for vulcanized rubber). It was created. Next, the appearance of the sample was determined by visually observing the surface and cut surface for the presence or absence of foaming, and the tensile strength, elongation, and hardness were determined using the JIS K63Ol method, and the volume resistivity (Ω・C!n) was determined. Measurements were made in accordance with JEC148 (Japan Institute of Electrical Engineers of Japan regulations), and the results are shown in the following table. Comparative Example 1 As shown in the following table, in this case, samples were prepared in the same manner as in Example 1 except that the organic titanium compound was removed, and observations and measurements were conducted in the same manner as in Example. The details are shown in the table below.

Comparative Example 2 As shown in the following table, samples were prepared in the same manner as in the example except that carbon black (2) was used in this case at 4.0 parts by weight, and the same observations and measurements as in the example were carried out. The results for each are shown in the table below.

Comparative Example 3 As shown in the following table, the same formulation as in Example was used except that carbon black (2) was 40.0 parts by weight and organic titanium compound was 5 parts by weight or more. Even when kneading is performed, it does not form into a roll (
As a result, it was not possible to observe or measure the properties of the compound (the mixture did not flow together), and as a result it was not possible to prepare a sample, and as a result, it was not possible to observe or measure the properties.

The reason for not being able to roll it is thought to be due to the increased amount of carphone. Comparative Example 4 As shown in the table below, the procedure was the same as in Example 1 except that the amount of the organic titanium compound was increased by more than 5 parts by weight. Moreover, the same observations and measurements as in the example were carried out, and the respective results were Shown in the table below.

Comparative Example 5 As shown in the following table, carbon black (3) with a surface area less than 500 i/q was used instead of carbon black (2).
) and (4) and an organic titanium compound were added.

Comparative Example 6 As shown in the following table. In this case, a hose-like article was extruded using the same extrusion method as in the example using a compound having the same composition as in Comparative Example 1, the extruded hose was immediately cooled, and then the hose was cut open and
110 TmIn was placed in a 1.5 T$L mold, and pressurized to 100 k9/d with a press having a hot plate, and 16
A vulcanized sheet was produced after heating the powder at 0°C, and a sample suitable for use in the JIS K63Ol method was prepared in the same manner as described above. Observations and tests were conducted in the same manner as in the examples, and the results were are shown in the table below.

In addition, in the above table, the specific materials of the compounding materials (numbers with 0 in the compounding column) are as follows.

(1)...Urepan 640 (manufactured by West German Bayer AG) (2)...Ketchen Black EC (manufactured by Japan EC Co., Ltd.) DBP oil absorption 350m1/100
y surface area (nitrogen adsorption method) 950 i/y (3)... Seast 3 (Tokai Electrode carbon black [HAF)] DBP oil absorption 102 m1/100
y Surface area (nitrogen adsorption method) 100 d/y (4) ... Konite MT (carbon black [MT] manufactured by Konite Carbon Co., Ltd.) DBP oil absorption 350 m
1/100y Surface area (nitrogen adsorption method) 67T1/y (5)... Isopropyl triisostearoyl titanate (6)... Tetraisopropylbis (
Dioctyl phosphite) titanate (7)...
Tetraoctylbis(ditridecylphosphite) titanate (C8Hl7-0+-4T1[P-(0-) To summarize the results above, the conductivity is determined by the volume resistivity, although it depends on the amount of carbon black blended in the examples. 1σ ~ 1σ
It has properties of Ωα, and shows good properties in both tensile strength and elongation.

On the other hand, comparative example 1 has the tensile strength, elongation, and hardness of example 1.
However, the volume resistivity is as large as 10 7 Ω·d, which is insufficient as a conductive or semiconductive comb. Comparative Example 2 is a case where carbon black is small, and Comparative Example 3 is a case where carbon black is large, but good vulcanized rubber cannot be obtained in either case.
In Comparative Example 4, the amount of the organic titanium compound of Example 1 was increased to 5 parts by weight or more, but the tensile strength decreased and it could not be put to practical use.

Comparative Example 5 uses ribbon black with a smaller surface area than the claimed range, but it foams during normal pressure vulcanization, making it impossible to obtain a product with a good appearance. Comparative Example 6 was obtained by press vulcanizing the same formulation as Comparative Example 1, but in terms of volume resistivity, tensile strength, elongation, etc., the product according to the present invention is superior to normal press vulcanization even when vulcanized at normal pressure. It can be seen that simultaneous characteristics can be obtained. Therefore, according to the present invention, the equipment cost is lower than conventional press vulcanization or vulcanization in a vulcanization can, and continuous vulcanization is possible in hot air at normal pressure, which has great industrial value. There is something.

Claims (1)

[Claims] 1 Ester-based urethane rubber that can be crosslinked with peroxide,
DBP oil absorption amount according to ASTM D2414 is 250ml/
100g or more and the surface area by nitrogen adsorption method is 500m^2
/g or more of conductive carbon black per 100 parts by weight of the urethane rubber, and 0.05 to 5 parts by weight of an organic titanium compound having an alkoxy residue per 100 parts by weight of the conductive carbon black. An electrically conductive urethane rubber composition that can be vulcanized at atmospheric pressure and is characterized by being formed by blending the following.