JP2006070137A - Manufacturing method of rubber product and rubber product obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a rubber product which is excellent in gas permeability resistance (gas-barrier property) and retains its rubber physical property, and the rubber product obtained thereby. <P>SOLUTION: In the method, the rubber product is formed using a rubber composition essentially comprising (A) a rubber latex, (B) an aqueous montmorillonite suspension and (C) a surfactant having a dispersion effect against montmorillonite. The rubber composition is prepared by stirring components (A), (B) and (C) at a high speed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a rubber product and a rubber product obtained by the method, and more particularly to a method for producing a rubber product such as a hose, a gasket and a packing, and a rubber product obtained thereby.

Conventionally, rubber products such as air conditioner refrigerant transport hoses, for example, contain a large amount of flaky filler such as talc in the material, and have gas permeability resistance (gas barrier property) due to the blocking action due to the overlapping of the flank. (Refer to Patent Document 1). In order to develop the above gas barrier properties, the rubber product material is mixed with a layered clay mineral such as montmorillonite which is swollen and dispersed in water, and then the moisture is removed by drying to give a rubber composition. There is also proposed a technique for preparing a rubber product, thereby producing a rubber product (see Patent Document 2). Thus, when the layered clay mineral is swollen and dispersed in advance with water, the dispersibility becomes good, and the gas barrier property of the resulting rubber product becomes high.
Japanese Patent Laid-Open No. 11-257551 JP 2003-327711 A

  However, in order to ensure a sufficient gas barrier property, the conventional method cannot be achieved unless the amount of filler such as montmorillonite is increased. As described above, when a large amount of the filler is contained, there is a concern that the rubber physical properties such as flexibility may be adversely affected.

  The present invention has been made in view of such circumstances, and its object is to provide a method for producing a rubber product having excellent gas permeation resistance (gas barrier properties) while ensuring rubber physical properties and a rubber product obtained thereby. To do.

In order to achieve the above object, the present invention provides a method for producing a rubber product formed using a rubber composition comprising the following (A) to (C) as essential components, and the preparation of the rubber composition: At that time, the manufacturing method of the rubber product in which the components (A) to (C) are stirred at high speed is the first gist, and the rubber product formed by the above manufacturing method is the second gist.
(A) Rubber latex.
(B) An aqueous suspension of montmorillonite.
(C) A surfactant having a dispersing effect on montmorillonite.

  That is, in order to solve the above problems, the present inventor opens each layer of montmorillonite, which is a layered clay mineral, improves the dispersion level of montmorillonite in rubber, and has a gas barrier property without adding a large amount of montmorillonite. The research was repeated for the purpose of ensuring. During the course of the research, the rubber latex and montmorillonite aqueous suspensions were used in the preparation of the rubber composition, rather than simply swelling and dispersing the montmorillonite with water and mixing this into the rubber composition as in the past. The idea was to mix a surfactant having a dispersion effect on montmorillonite, such as pyrophosphoric acid and alkylbenzene sulfonic acid, with the liquid. When an experiment was conducted based on this, the above-mentioned surfactant increased the dispersibility of the montmorillonite plate-like particles forming the layer and increased the distance between the plate-like particles and the plate-like particles to create a space. I found out that it would be easier for rubber to enter the space. In this state, if the fluid composed of the rubber composition is subjected to high-speed stirring, the rubber can be effectively introduced between the montmorillonite plate-like particles. It has been found that dispersion can be realized and the present invention has been reached.

  Here, “high-speed stirring” as used in the present invention can be performed by a high-speed stirrer such as a homogenizer, and the stirring blade (rotary shaft having the stirring blade) is rotated at a speed of 10,000 rotations / minute or more. Stirring. Usually, this high-speed stirring consists of a rotating shaft having 2 to 4 stirring blades and a stirring tank that accommodates the rotating shaft, and the amount of the composition in the stirring tank is determined by the composition liquid in contact with the inner wall of the stirring tank. The liquid amount is set so as to be rotated by the rotation of the stirring blade. The effect of the high-speed stirring can be obtained by setting the amount of liquid. The high-speed stirring is difficult with a general-purpose mixer such as a stirrer mixer because the stirring speed is low.

  Further, the “essential component” in the above description of “having (A) to (C) as essential components” refers to an optional component, which is a component that is necessarily contained in terms of configuration, There are no restrictions.

  As described above, in the present invention, the rubber latex, the aqueous montmorillonite suspension, and the specific surfactant are stirred at a high speed to prepare a rubber composition, thereby producing a desired rubber product. Therefore, it is possible to effectively finely disperse montmorillonite in the rubber product than before. Further, gas permeation is blocked by the dispersed montmorillonite, and since the dispersion can be nano-dispersed, good properties can be exhibited without impairing rubber physical properties such as flexibility. Therefore, in particular, it can be suitably used as a rubber product such as a refrigerant transport hose of an air conditioner, an automobile engine cooling system hose, a fuel system hose, or the like.

  In particular, when the specific surfactant is at least one selected from the group consisting of pyrophosphoric acid compounds, polyoxyethylene alkylphenyl ethers and alkylbenzene sulfonic acids, the fine dispersibility of montmorillonite particles is further improved, A rubber product exhibiting better properties can be obtained.

  Moreover, when the blending ratio of the specific surfactant is set in the range of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of montmorillonite, the gas barrier property becomes excellent.

  Next, embodiments of the present invention will be described in detail.

  In the present invention, as described above, the rubber latex (component A), the montmorillonite aqueous suspension (component B) and the specific surfactant (component C) are stirred at high speed to prepare a rubber composition. Thus, the intended rubber product is manufactured.

  The rubber latex (component A) used in the rubber composition of the present invention is not particularly limited, and examples thereof include natural rubber, styrene butadiene rubber (SBR), butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber (NBR), and butyl rubber. (IIR), hydrogenated NBR (H-NBR), fluoro rubber, urethane rubber, ethylene-propylene-diene terpolymer (EPDM), ethylene-propylene copolymer (EPM), rubber made of halogenated butyl rubber, etc. Latex. These may be used alone or in combination of two or more.

  The aqueous montmorillonite suspension (component B) used together with the rubber latex of the above component A contains 100 parts by weight (hereinafter abbreviated as “part”) of montmorillonite with water at a ratio of about 1500 to 3000 parts. , Prepared.

  The blending ratio of montmorillonite (dry weight) in component B is preferably set in the range of 1 to 20 parts, more preferably 5 to 10 parts per 100 parts of rubber latex (solid content) of component A. Part range. That is, if the montmorillonite is less than 1 part, the desired gas permeation resistance effect cannot be sufficiently obtained. Conversely, if it exceeds 20 parts, the physical properties of the rubber product such as flexibility are adversely affected. Because.

  As the specific surfactant (C component) used together with the A component and the B component, a surfactant having a dispersion effect on montmorillonite is used. Such a surfactant is not particularly limited, and preferable examples thereof include pyrophosphoric acid compounds such as pyrophosphoric acid, potassium pyrophosphate, and sodium pyrophosphate, polyoxyethylene alkylphenyl ether, and alkylbenzene sulfonic acid. . That is, since these specific compounds have the effect of further improving the fine dispersibility of the montmorillonite particles, the use thereof makes it possible to obtain better characteristics in the rubber product of the present invention. In addition, the said surfactant is used individually or in combination of 2 or more types.

  The blending ratio of the specific surfactant which is the C component is preferably set in the range of 0.1 to 5.0 parts, more preferably 100 parts of the montmorillonite (dry weight) in the B component. Is in the range of 0.3 to 3 parts. When it is set within such a range, the balance between gas barrier properties and rubber physical properties such as flexibility becomes more excellent.

  In addition to the above-mentioned components A to C which are essential components, the rubber product forming material of the present invention includes a vulcanizing agent, a vulcanization accelerator, a vulcanizing aid, and an aging as long as the physical properties are not impaired. An inhibitor, a processing aid, a softener, a reinforcing agent such as carbon black, a filler such as calcium carbonate, and the like may be blended as necessary.

  Sulfur is preferably used as the vulcanizing agent. The amount of sulfur is preferably in the range of 0.3 to 10 parts, particularly preferably in the range of 0.5 to 5 parts, with respect to 100 parts of the rubber latex (solid content) of the component A.

  The vulcanization accelerator is not particularly limited. For example, thiazole accelerator, thiuram accelerator, N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide (MBTS), 2 -Sulfenamide accelerators such as mercaptobenzothiazole (MBT) and tetramethylthiuram monosulfide (TMTM).

  The blending amount of the vulcanization accelerator is preferably in the range of 0.1 to 3 parts, particularly preferably in the range of 0.5 to 2 parts, with respect to 100 parts of the rubber latex (solid content) of the component A. It is.

  The vulcanization aid is not particularly limited, and examples thereof include zinc oxide (ZnO) and magnesium oxide. These may be used alone or in combination of two or more.

  The blending amount of the ZnO is preferably 10 parts or less with respect to 100 parts of the rubber latex (solid content) of the component A. If it is in such a range, it will be in a normal range, and there will also be no problem of the weight increase of the product accompanying the increase in ZnO.

  Examples of the antiaging agent include carbamate type antiaging agent, phenylenediamine type antiaging agent, phenol type antiaging agent, diphenylamine type antiaging agent, quinoline type antiaging agent, and waxes.

  The blending amount of this anti-aging agent is preferably in the range of 1 to 7 parts, particularly preferably in the range of 2 to 5 parts, with respect to 100 parts of the rubber latex (solid content) of the component A.

  Examples of processing aids include stearic acid, fatty acid esters, fatty acid amides, hydrocarbon resins, and the like.

  The amount of the processing aid is preferably in the range of 1 to 5 parts, particularly preferably in the range of 1 to 3 parts, with respect to 100 parts of the rubber latex (solid content) of the component A.

  The rubber product of the present invention can be produced, for example, as follows. That is, first, the above A to C component materials are prepared, and other component materials (other than the vulcanizing agent) are also prepared as necessary, and these are put into a stirring tank and stirred at high speed. In the high-speed stirring, it is necessary to stir at a speed of 10,000 revolutions / minute or more with a high-speed stirrer such as a homogenizer. Preferably, the stirring speed is in the range of 13,000 to 20000 rpm. By stirring at such a high speed, rubber can be effectively introduced into the space between the plate-like particles of montmorillonite forming the layer, and the fine dispersibility of the montmorillonite particles can be improved. Can do. Then, after stirring at high speed, the moisture in the composition is blown off by vacuum drying or the like, and further, kneaded with a kneader such as a roll or a mixer while being added to the vulcanizing agent, vulcanization accelerator, vulcanization aid. A desired rubber composition can be obtained by adding an agent, a reinforcing agent, a filler and the like. Then, after the rubber composition thus prepared is subjected to extrusion molding or the like, it is heat vulcanized or press vulcanized to form a rubber product of the present invention. Can be manufactured.

  The rubber product of the present invention thus obtained is used, for example, as a refrigerant transport hose for an air conditioner, a radiator hose used for connecting an engine and a radiator in a vehicle such as an automobile, and a connection between the engine and a heater core. Water-based hoses such as an engine cooling system hose such as a heater hose, and a fuel cell system hose in a fuel cell electric vehicle (FCEV), fuel hoses, gaskets, and various packings are preferable.

  Next, examples will be described together with comparative examples.

  150 parts of NBR latex (manufactured by Nippon Zeon, Nipol LX517A) and an aqueous suspension of montmorillonite (montmorillonite (Hojun Co., Bengel A) 5 parts suspended in 100 parts of water) and pyrophosphate (Kanto) 0.3 parts (made by Kagaku Co., Ltd.) was stirred at a high speed for 3 minutes at a rate of 13000 rpm with a homogenizer (manufactured by Nippon Seiki Seisakusho). Subsequently, it dried until the moisture content in this composition became 0.5 weight% or less by vacuum drying. Thereafter, 5 parts of zinc oxide (Mitsui Metals Co., Ltd., 2 types of zinc oxide), 1 part of stearic acid (Kao Co., Ltd., LUNAC S30), and a vulcanization accelerator (manufactured by Sanshin Chemical Co., Ltd.) A rubber composition was prepared by blending 1 part of Sunseller CZ-G) and 1 part of sulfur (manufactured by Tsurumi Chemical Industry Co., Ltd., Sulfax T10) and continuing kneading using a roll. Then, using the rubber composition prepared above, this was formed into a sheet having a thickness of 2 mm and crosslinked at 160 ° C. for 30 minutes to prepare a sample sheet (120 mm × 120 mm × thickness 2 mm).

  The amount of montmorillonite blended when preparing the aqueous montmorillonite suspension was 10 parts. Except for this, a rubber composition was prepared in the same manner as in Example 1 to prepare a sample sheet.

[Comparative Example 1]
When preparing the rubber composition, no pyrophosphate was added. Other than that was carried out similarly to Example 1, the rubber composition was prepared, and the sample sheet was produced.

[Comparative Example 2]
When preparing the rubber composition, no pyrophosphate was added. Other than that was carried out similarly to Example 2, and the rubber composition was prepared and the sample sheet was produced.

[Comparative Example 3]
Rolls containing 5 parts of montmorillonite, 5 parts of zinc oxide, 1 part of stearic acid, 1 part of vulcanization accelerator, and 1 part of sulfur with respect to 100 parts of the solid content obtained by removing water from the NBR latex A rubber composition was prepared by kneading using a, and a sample sheet was prepared using this as in Example 1.

[Comparative Example 4]
The blending amount of montmorillonite was 10 parts. Other than that prepared the rubber composition similarly to the comparative example 3, and produced the sample sheet.

  Using the sample sheets of Examples and Comparative Examples thus obtained, each characteristic was evaluated according to the following criteria. These results are shown in Table 1 below.

[Nitrogen gas permeability coefficient, gas barrier properties]
For each sample sheet, the nitrogen gas permeability coefficient was measured by a gas permeability measuring device MT-C3 (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a test temperature of 50 ° C. according to the pressure method of JIS K 7126. In the gas barrier property evaluation, if the nitrogen gas permeability coefficient is less than 3.00 × 10 ⁻¹⁰ (cm ³ cm / cm ² sec cmHg at 50 ° C.), it is evaluated as “good”, and 3.00 × 10 ^{− If it was 10} (cm ³ cm / cm ² sec cmHg at 50 ° C.) or more, it was evaluated as x.

  From the above results, it can be seen that the sample sheets (rubber products) of all Examples are excellent in gas barrier properties.

  On the other hand, the sample sheet of the comparative example was not as good in dispersibility of montmorillonite as the example product, and thus the desired gas barrier property required for the present invention was not obtained.

Claims (4)

A method for producing a rubber product formed by using a rubber composition having the following (A) to (C) as essential components, and in the preparation of the rubber composition, the components (A) to (C) are stirred at high speed. A method for producing a rubber product characterized by:
(A) Rubber latex.
(B) An aqueous suspension of montmorillonite.
(C) A surfactant having a dispersing effect on montmorillonite.   The process for producing a rubber product according to claim 1, wherein the surfactant of the component (C) is at least one selected from the group consisting of pyrophosphate compounds, polyoxyethylene alkylphenyl ethers and alkylbenzene sulfonic acids.   The rubber product according to claim 1 or 2, wherein a blending ratio of the component (C) is set in a range of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the montmorillonite in the component (B). Manufacturing method.   A rubber product formed by the manufacturing method according to any one of claims 1 to 3.