JP2004210820A5 - - Google Patents

Description

(1)
Ethylene-propylene-polymer, by adding an additive that exhibits chlorine water resistance and vulcanizing, in a chlorine-resistant water-resistant rubber composition that has improved durability against chlorine-containing liquids,
A chlorine-resistant water-resistant rubber composition, wherein a phenol resin having a three-dimensional crosslinked structure is used as the additive.

(2)
The chlorine-resistant water-resistant rubber composition according to claim 1, wherein the phenol resin is completely cross-linked .

[0010]
[Means for Solving the Problems]
In order to overcome the above problems and achieve the intended purpose, the chlorine-resistant water-based rubber composition according to the present invention is:
Ethylene-propylene-polymer, by adding an additive that exhibits chlorine water resistance and vulcanizing, in a chlorine-resistant water-resistant rubber composition that has improved durability against chlorine-containing liquids,
A phenol resin having a three-dimensional crosslinked structure is used as the additive.

Next, an example of a manufacturing process of a chlorine-resistant water-based rubber composition according to an example using each of the above-described elements will be briefly described with reference to FIG. First, primary mixing is performed in which an appropriate amount of an EP polymer as a raw rubber composition and a cured spherical phenol resin are mixed into a rubber composition kneader and mixed. The required amount of softeners, fillers, reinforcing materials such as carbon black, cross-linking agents such as powdered sulfur and organic peroxides, cross-linking accelerators, cross-linking accelerators, antioxidants, and antiozonants (anti-aging ) And the like. Wherein the implementation of the primary and secondary mixing, 1-shaft or two-shaft extruder, kneader, pressurized kneader, co-kneader, a Banbury mixer, Henschel mixer some have preferred that B over data mixer Other kneader Used for Thereafter, the EP mixture is filled in a predetermined mold, or the like to form a molded body, while the mold is attached to a vulcanizing apparatus represented by a vulcanizer, and heated by steam or the like for a certain period of time. A vulcanized rubber composition having a required shape is obtained. Then, the rubber composition is removed from the mold and cooled to complete a chlorine-resistant water-resistant rubber composition. The vulcanization time is appropriately adjusted depending on conditions such as the size of the chlorine-resistant water-based rubber composition to be obtained and additives. In addition to the molding method using the molding die described above, any conventionally known molding method such as extrusion molding or injection molding can be used. In this case, separately and have One the obtained molded body, it is necessary to carry out heating for vulcanization, it is possible to continuously and efficiently manufactured.

The physical properties required for the packing for water supply can be generally defined by hardness, tensile strength, elongation, bulk density, compression set and the like. In addition, when the water packing is in an environment where heat is applied or exposed to the outside environment, the rubber composition may be evaluated by heat aging characteristics (100 ° C. or 70 ° C., 24 hours). However, in the present invention, in consideration of the use as the packing for water supply in an environment where a chemical load and a physical load are applied, an evaluation based on compression set is incorporated as the physical property value. That the water gasket has always been exposed to chlorine in tap water is used in a state in which force is compressed applied, physical properties which are important in order to function well as the packing, hanging on the ongoing This is because it is considered to be recoverability to a certain compression force. Therefore, the physical properties of the chlorine-resistant water-based rubber composition according to the examples were determined in accordance with actual use conditions by using compression set as an index for evaluation. As a criterion, a compression set of 30% or less, which is generally adopted for the packing for water supply, is desirable, and the rubber composition obtained by either peroxide vulcanization or sulfur vulcanization in the present invention In the product, a load is applied to the test piece at 70 ° C. according to JIS K 6353 so as to have a constant compression ratio of 25%, and after 24 hours, the load is removed and the test piece remains in the compression direction when left for a specified time. The permanent set is measured, and the compression set is set so as to be 30% or less.

[0023]
[Experimental example]
Hereinafter, experimental examples showing respective physical property values of the chlorine-resistant water-based rubber composition according to the present invention will be described. The chlorine-resistant water resistance is determined by mixing an EP polymer (here, an EPDM polymer) and various additives described below ([0025]) and additives such as a cured spherical phenol resin in a ratio shown in Table 1 below. The obtained EP mixture is molded into a required shape using a general-purpose extrusion molding machine or injection molding machine, and the molded body is processed to obtain a predetermined test piece (for mixing and chlorine resistance, the width is 20 m).
m, length 50 mm, thickness 2 mm, compression set: large (diameter 29.0 mm ± 0.5 mm, thickness 12.5 mm ± 0.3 mm) according to JIS K 6262, and then vulcanized It is obtained by processing and cooling. For each of the obtained test pieces of Examples 1 to 5 and Comparative Examples 1 to 4, mixing properties (easy to mix: 、, difficult to mix: X), compression set (%) ) And chlorine resistance were observed and measured respectively. As a comparative example,
Solid body made of base formulation only (Comparative Example 1), a phenol resin A (Comparative Example 2) shown in the conventional example, if the phenolic resin B (Comparative Example 3) was added to EP polymer with the same percentage Compare with Furthermore, a comparison is made with the case where the same amount of hydrotalcite is added as an additive for imparting chlorine water resistance.

(result)
The results are shown in Table 1 above. From Table 1, when the spherical phenol resin cured product is added in the range of 5 to 50 parts by weight with respect to 100 parts by weight of the EP polymer, while exhibiting good chlorine water resistance, the deterioration of the physical properties of the rubber composition itself is suppressed. and Rukoto obtained a salt-containing aqueous rubber composition capable of expressing a compression set of 30% or less was confirmed.