JP2000080207A - Production of clay-rubber composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for a clay-rubber composite material in which clay minerals can readily and inexpensively attain its uniform dispersion in the rubber. SOLUTION: In this production process, a clay mineral that is organized with an organic onium ion, rubber, a clay mineral dispersant a vulcanizing agent are kneaded together and vulcanized to give a clay-rubber composite material in which the clay mineral is uniformly dispersed in the rubber. The clay mineral dispersant can form radicals by its own thermal decomposition to allow the radicals to bond to the rubber molecules and acts simultaneously as a vulcanization accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a clay-rubber composite material in which clay minerals are uniformly dispersed in rubber.

[0002]

2. Description of the Related Art Conventionally, clay minerals have been added to rubber in order to improve the mechanical properties and gas barrier properties of rubber materials.
The development of a mixed clay-rubber composite is under consideration. The most important issue in the production of clay-rubber composite materials is how to uniformly disperse the clay mineral in the rubber. In this regard, it is known that it is effective to modify the rubber with maleic anhydride.

[0003]

However, the above-mentioned conventional production method using maleic acid-modified rubber has problems such as an increase in cost due to maleic acid treatment and a decrease in production efficiency due to modification treatment. Therefore, it has been desired to develop a method for easily dispersing the clay mineral in the rubber without using a maleic acid-modified rubber.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method for producing a clay-rubber composite material capable of easily and inexpensively uniformly dispersing a clay mineral in rubber. Things.

[0005]

According to the first aspect of the present invention, a clay mineral organically formed by an organic onium ion, a rubber, a clay mineral dispersant, and a vulcanizing agent are kneaded and then vulcanized. A method for producing a clay-rubber composite material in which the clay mineral is uniformly dispersed in the rubber, wherein the clay mineral dispersant generates radicals by thermal decomposition of the clay mineral dispersant itself, and generates radicals. A method for producing a clay-rubber composite material, which has a property of binding to rubber molecules and a property as a vulcanization accelerator.

The most remarkable point in the present invention is to use the above-mentioned organic clay mineral and vulcanize it by adding a clay mineral dispersant having the above properties to a kneaded product of the clay mineral and rubber. is there.

[0007] As the above-mentioned clay mineral, one that has been organically treated with an organic onium ion as described above is used. Examples of the organic onium ion include hexyl ammonium ion, octyl ammonium ion, 2-ethylhexylammonium ion, dodecyl ammonium ion, octadecyl ammonium ion, dioctyl dimethyl ammonium ion, trioctyl ammonium ion, distearyl dimethyl ammonium ion, and trimethyl octadecyl ammonium. Ion, dimethyl octadecyl ammonium ion, methyl octadecyl ammonium ion, trimethyl dodecyl ammonium ion, dimethyl dodecyl ammonium ion, methyl dodecyl ammonium ion, trimethyl hexadecyl ammonium ion, dimethyl hexadecyl ammonium ion, methyl hexadecyl ammonium ion, etc. Kill.

Further, 1-hexenyl ammonium ion, 1-dodecenyl ammonium ion, 9-octadecenyl ammonium ion (oleyl ammonium ion), 9,12-
Octadecadienylammonium ion (linoleammonium ion), 9,12,15-octadecatrienylammonium ion (linoleylammonium ion) and the like can also be used.

The clay mineral has a cation exchange capacity of 50 to 200 milliequivalents (meq) / 1 so that the interlayer of the clay mineral can be largely swollen.
It is preferably 00 g. 50 meq (meq)
If it is less than / 100 g, onium ions may not be sufficiently exchanged, and it may be difficult to swell between layers of the clay mineral. On the other hand, 200 meq (meq) / 10
If it exceeds 0 g, the bonding strength between the layers of the clay mineral becomes strong, and it may be difficult to swell between the layers of the clay mineral.

The clay minerals include, for example, smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, and nontronite, vermiculite, halloysite, and swelling mica. It may be natural or synthetic.

Next, in the rubber, the ratio of the number of unsaturated bonds to the number of carbon-carbon bonding parts in the main chain is 50%.
The following rubbers or copolymers containing the same are preferred. If it exceeds 50%, it is likely to be chemically attacked, so the vulcanization rate is high, that is, the reaction rate between the clay mineral and the radical generated by thermal decomposition of the clay mineral dispersant is higher than the vulcanization rate. Slowly, clay minerals may not disperse. Further, it is more preferably at most 30%, most preferably at most 20%.

As a specific example of the rubber, for example, EP
DM (ethylene-propylene-non-conjugated diene terpolymer), IIR (butyl rubber (isobutene-isobrene copolymer)), IR (isoprene rubber), NR (natural rubber), BR (butadiene rubber), NBR (nitrile) Rubber (acrylonitrile-butadiene copolymer)), SBR
(Styrene / butadiene rubber), H-NBR (hydrogenated nitrile rubber), FKM (fluoro rubber), ACM (acrylic rubber), silicone rubber, and the like.

Next, as described above, the clay mineral dispersant has the property of generating radicals by thermal decomposition of the clay mineral dispersant itself and binding the radicals to rubber molecules, and also has the property of being a vulcanization accelerator. Use a material with properties. Specific examples of the clay mineral dispersant include, for example, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide and tetramethylthiuram monosulfide as thiuram-based vulcanization accelerators , Tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide and the like.

Further, for example, as a dithiocarbamate-based vulcanization accelerator, pentamethylenedithiocarbamate piperidine salt, pipecolyldithiocarbamate pipecolic acid, zinc dimethyldithiocarbamate, diethyldithiocarbamate, zinc dibutyldithiocarbamate, N- Zinc ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, tellurium diethyldithiocarbamate, etc. Can also be used.

Further, for example, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene as sulfenamide vulcanization accelerators −
2-benzothiazolylsulfenamide, N, N-dicyclohexyl-2-benzothiazolylsulfenamide and the like can also be used.

Also, for example, among the thiazole vulcanization accelerators, dibenzothiazyl sulfide and 2-mercaptobenzothiazole as 2,2-benzothiazolyl sulfide vulcanization accelerators (abbreviated MBTS). Cyclohexylamine salts, 2- (4′-morpholinodithio) benzothiazole, and the like can also be used. Further, as other vulcanization accelerators, vulcanization accelerators having an SS bond or an SN bond, 4,4'-dithiodimorpholine, and the like can also be used.

Further, as the vulcanizing agent, for example, sulfur,
Use sulfur monochloride, sulfur dichloride, etc. Further, if necessary, a vulcanization aid can be further added. As the vulcanization aid, for example, fatty acids represented by stearic acid, metal oxides represented by zinc white, and the like can be used.

Next, the operation of the present invention will be described. In the present invention, a clay mineral dispersant having the above characteristics is used while the above clay mineral is organically treated with an organic onium ion. Therefore, uniform dispersion of the clay mineral in the rubber can be easily and reliably performed.

The reason is considered as follows. That is,
The clay mineral dispersant generates radicals by thermal decomposition of itself. These radicals are very chemically active and have the property of easily bonding to rubber molecules. Therefore, the thermally decomposed product of the viscous mineral dispersant bonded to the rubber molecule by the radical bonds to the organized clay mineral. At the time of vulcanization, the rubber molecules are flowing due to the high temperature, and are dragged by the flow of the rubber molecules, and are combined with the thermal decomposition product of the clay mineral dispersant to disperse the organized clay mineral.

The clay mineral dispersant has properties as a vulcanization accelerator. Therefore, when combined with the vulcanizing agent, the effect of shortening the vulcanizing time and reducing the amount of the vulcanizing agent used can be obtained. It is considered that the clay mineral can be uniformly dispersed in the rubber in the vulcanization step by the action and effect of these clay-rubber composite materials.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A method for producing a clay-rubber composite material according to an embodiment of the present invention will be described. In this example, the rubber is E
Six types of clay rubber composite materials using PDM (ethylene-propylene-non-conjugated diene terpolymer) (Example E1)
1 to E16), and their characteristics were evaluated.

The production of the clay-rubber composite material in this example is as follows.
All were carried out by kneading a clay mineral organically formed by organic onium ions, rubber, a clay mineral dispersant, and a vulcanizing agent, followed by vulcanization. The clay mineral dispersant has a property of generating a radical by thermal decomposition of the clay mineral dispersant itself and binding the radical to a rubber molecule, and also has a property as a vulcanization accelerator. Different substances were used in Examples E11 to E16 (Table 1).

Hereinafter, the above manufacturing method will be specifically described.
First, the following materials were blended and kneaded using a roll. (1) Rubber: EPDM (Sumitomo Chemical Esplen E505)
(2) Organized clay mineral: 10 parts by weight of montmorillonite (C18-Mt) organically treated with octadecylamine, (3) Clay mineral dispersant: 1.5 parts by weight of those described in Table 1. (4) Vulcanizing agent: 1.5 parts by weight of sulfur, (5) Vulcanizing aid: 1 part by weight of stearic acid and 5 parts by weight of zinc white.

Next, the kneaded raw material is heated at a temperature of 160.
The mixture was vulcanized at 30 ° C. for 30 minutes to form a sheet (0.5 mm thick and 2 mm thick) as a clay rubber composite material. In this example, for comparison, Comparative Example C in which zinc dimethyldicarbamate as a vulcanization accelerator was added to EPDM.
1 was prepared. The comparative example C1 includes the above (2)
No organic clay mineral was added. Then, vulcanization treatment was performed in the same manner as described above to produce rubber sheets having a thickness of 0.5 mm and 2 mm.

For comparison, a comparative example C2 was prepared in which 2-mercaptobenzothiazole was used as a vulcanization accelerator having no effect as a clay mineral dispersant, and the other conditions were the same as in the above example. In Comparative Example C2, rubber sheets having thicknesses of 0.5 mm and 2 mm were obtained by the same manufacturing method as described above.

Next, using the clay-rubber composite material sheets (thickness 0.5 mm) of Examples E11 to E16, the dispersion state of the clay mineral in the rubber was investigated. Specifically, X
The interlayer distance of montmorillonite (clay mineral) in the clay-rubber composite material was measured by a line diffraction method.

As a result, no peak indicating the layer of montmorillonite was observed, or the peak indicating the layer of montmorillonite was shifted to the lower angle side, and the montmorillonite was uniformly finely or uniformly dispersed in the rubber. I understood. Here, the fine dispersion refers to a state in which the montmorillonite layer is uniformly dispersed in a single layer state, and a state in which there is no montmorillonite peak in the X-ray measurement. On the other hand, the above-mentioned dispersion refers to a state in which a plurality of montmorillonite layers are uniformly dispersed in a stacked state, and a state in which the peak of montmorillonite shifts to a lower angle side in X-ray measurement.

FIGS. 1 and 2 show typical examples of the results of the X-ray diffraction.
Shown in FIG. 1 is an X-ray diffraction chart of Example E11, FIG.
Is an X-ray diffraction chart of Comparative Example C2. As can be seen from FIG. 1, in the case of Example E1, no peak of montmorillonite was observed, indicating that this was sufficiently finely dispersed. On the other hand, as is known from FIG.
In the case of (1), the peak P of montmorillonite is large, which indicates that montmorillonite is not finely dispersed or in a dispersed state.

Next, using the clay-rubber composite material sheets of Examples E11 to E16 and the rubber sheets of Comparative Examples C1 and C2, mechanical properties (using a sheet having a thickness of 2 mm) and gas barrier properties (using a sheet having a thickness of 0.5 mm) were used. Were used). First, breaking strength (MPa) and breaking elongation (%)
Was measured using a test piece dumbbell No. 3 at a tensile speed of 500 mm / min in accordance with the tensile test method in the vulcanized rubber test method of JIS-K630.

The 100% tensile stress (MPa) is expressed by J
It was measured under the same conditions as in the tensile strength and elongation tests of IS-K630. The storage modulus (MPa) is the strain ±
0.5%, frequency 10Hz, distance between chucks 30mm,
The measurement was performed under the condition of a temperature of 25 ° C. The gas permeability was measured by measuring the amount of N ₂ gas per unit time per unit time under the conditions of a measured gas permeation area of 16.2 cm ² and a temperature of 60 ° C.

Table 1 shows the results of these measurements. As can be seen from Table 1, the products of the present invention, Examples E11 to E16
Each of the clay-rubber composite materials of No. 1 exhibited significantly improved mechanical properties and gas permeability as compared with Comparative Examples C1 and C2.

[0032]

[Table 1]

Embodiment 2 In this embodiment, IIR (butyl rubber) is used as the rubber.
Types of clay-rubber composite materials (Examples E21 to E21)
26) Fabricated and evaluated its characteristics. Examples E21 to E
In Example 26, the following raw materials were used, and
Performed in the same manner as described above, with a thickness of 0.5 mm and
Was prepared.

The raw materials of Examples E21 to E26 are as follows. (1) Rubber: IIR (Japan Synthetic Rubber Buty 1268)
(2) Organized clay mineral: 10 parts by weight of montmorillonite (C18-Mt) organically treated with octadecylamine, (3) Clay mineral dispersant: 1.5 parts by weight of those described in Table 2 (4) Vulcanizing agent: 1.5 parts by weight of sulfur, (5) Vulcanizing aid: 1 part by weight of stearic acid and 5 parts by weight of zinc white.

Also in this example, for comparison,
An IIR containing no clay mineral was prepared as Comparative Example C3. In Comparative Example C3, vulcanization treatment was performed in the same manner as described above except that the organized clay mineral of (2) and the clay mineral dispersant of (3) were not added, and rubber sheets having a thickness of 0.5 mm and 2 mm were used. It was made so that it might become.

Next, using the clay-rubber composite material sheets (thickness 0.5 mm) of Examples E21 to E26, the dispersion state of the clay mineral in the rubber was investigated in the same manner as in Example 1. As a result, no peak between the layers of montmorillonite was observed, or the peak between the layers of montmorillonite was shifted to the lower angle side, indicating that the montmorillonite was uniformly finely or uniformly dispersed in the rubber. .

Next, using the clay-rubber composite material sheets of Examples E21 to E26 and the rubber sheet of Comparative Example C3, mechanical properties, gas barrier properties and the like were measured in the same manner as in Example 1. Table 2 shows the results. As can be seen from Table 2, the clay rubber composite materials of Examples E21 to E26, which are the products of the present invention, have significantly higher mechanical properties and gas permeability than Comparative Example C3 containing no clay mineral. Improved.

[0038]

[Table 2]

Embodiment 3 This embodiment is an embodiment in which the content of the organized clay mineral (montmorillonite) of Example E13 in Embodiment 1 is changed. Specifically, Example E31 had a montmorillonite content of 5% by weight, Example E32 had a montmorillonite content of 15% by weight, and the others were the same as Example E13 (Embodiment Example 1).

Then, for Examples E31 and E32,
In the same manner as in Example 1, observation of the clay dispersion state by X-ray diffraction and measurement of mechanical properties and gas barrier properties were performed. When the interlayer distance of montmorillonite in the clay-rubber composite material was measured by the X-ray diffraction method, Examples E31, E
In each of the samples No. 32, no peak indicating the interlayer of montmorillonite was observed, indicating that the montmorillonite was uniformly finely dispersed in the rubber.

Table 3 shows the measurement results of the mechanical properties and gas barrier properties. As can be seen from Table 3, Example E3
It was found that both E1 and E32 exhibited very excellent characteristics as compared with the comparative examples C1 and C2 (Embodiment 1).

[0042]

[Table 3]

Embodiment 4 This embodiment is an example in which the content of the organized clay mineral (montmorillonite) of Example E23 in Embodiment 2 is changed. Specifically, Example E41 had a montmorillonite content of 5% by weight, Example E42 had a montmorillonite content of 15% by weight, and the others were the same as Example E23 (Example 2).

Then, regarding Examples E41 and E42,
In the same manner as in Example 1, observation of the clay dispersion state by X-ray diffraction and measurement of mechanical properties and gas barrier properties were performed. When the interlayer distance of montmorillonite in the clay-rubber composite material was measured by the X-ray diffraction method, Example E41 showed that
No peak between the layers of montmorillonite was observed, and montmorillonite was uniformly finely dispersed in the rubber. In Example E42, the peak between the layers of montmorillonite was shifted to the lower angle side, and the montmorillonite was uniformly dispersed in the rubber.

Table 4 shows the measurement results of the mechanical properties and gas barrier properties. As can be seen from Table 3, Example E4
It was found that both E1 and E42 exhibited very excellent characteristics as compared with the above-mentioned Comparative Example C3 (Embodiment 2).

[0046]

[Table 4]

Embodiment 5 This embodiment is a modification of the embodiment E13 of the embodiment 1 according to the present invention.
This is an example in which the contents of a clay mineral dispersant and a vulcanizing agent are changed.
Specifically, as shown in Table 5, the content of zinc dimethyldithiocarbamate as a clay mineral dispersant was set to 0.75.
Examples E51 to E54 in which the content was changed in a range of from 4.5 to 4.5 parts by weight and the content of sulfur as a vulcanizing agent was changed in a range of from 0.75 to 4.5 parts by weight. Others were the same as Example E13 (Embodiment 1).

[0048]

[Table 5]

Then, regarding Examples E51 to E54,
In the same manner as in Example 1, observation of the clay dispersion state by X-ray diffraction and measurement of mechanical properties and gas barrier properties were performed. When the interlayer distance of montmorillonite in the clay-rubber composite material was measured by the X-ray diffraction method, Examples E51 to E
In No. 54, no peak indicating the interlayer of montmorillonite was observed, or the peak indicating the interlayer of montmorillonite was shifted to the lower angle side, and the montmorillonite was uniformly finely or uniformly dispersed in the rubber. I understood.

Table 6 shows the measurement results of the mechanical properties and gas barrier properties. As can be seen from Table 6, Example E5
It was found that each of 1 to E54 exhibited extremely excellent characteristics as compared with the above-described Comparative Examples C1 and C2 (Example 1).

[0051]

[Table 6]

Embodiment 6 This embodiment is different from Embodiment E23 of Embodiment 2 in that
This is an example in which the contents of a clay mineral dispersant and a vulcanizing agent are changed.
Specifically, as shown in Table 7, the content of zinc dimethyldithiocarbamate as a clay mineral dispersant was 0.75
Examples E61 to E64 in which the content was changed in a range of from 4.5 to 4.5 parts by weight and the content of sulfur as a vulcanizing agent was changed in a range of from 0.75 to 4.5 parts by weight. Others were the same as Example E23 (Embodiment 2).

[0053]

[Table 7]

Then, regarding Examples E61 to E64,
In the same manner as in Example 1, observation of the clay dispersion state by X-ray diffraction and measurement of mechanical properties and gas barrier properties were performed. When the interlayer distance of montmorillonite in the clay-rubber composite material was measured by the X-ray diffraction method, Examples E61 to E
No. 64 indicates that no peak between the layers of montmorillonite was observed or the peak between the layers of montmorillonite was shifted to the lower angle side, and the montmorillonite was uniformly finely or uniformly dispersed in the rubber. I understood.

Table 8 shows the measurement results of the mechanical properties and gas barrier properties. As can be seen from Table 8, Example E6
It was found that each of 1 to E64 exhibited very excellent characteristics as compared with Comparative Example C3 (Embodiment 2) described above.

[0056]

[Table 8]

[0057]

As described above, according to the present invention, it is possible to provide a method for producing a clay-rubber composite material which can easily and inexpensively disperse clay minerals in rubber.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction chart of Example E11 in Embodiment 1.

FIG. 2 is an X-ray diffraction chart of Comparative Example C2 in Embodiment Example 1.

[Explanation of symbols]

 P. . . Montmorillonite peak,

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Arimitsu Usuki 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-1 term in Toyota Central R & D Laboratories Co., Ltd. 4J002 BB151 DA048 DD008 DJ036 EV047 EV137 EV147 EV277 EV327 EV347 FB086 FD148 FD157

Claims (1)

[Claims] 1. Kneading a clay mineral, a rubber, a clay mineral dispersant, and a vulcanizing agent, organically formed by an organic onium ion, and then vulcanizing the clay mineral so that the clay mineral is uniformly dispersed in the rubber. A method for producing a clay-rubber composite material by dispersing, wherein the clay mineral dispersant has a property of generating radicals by thermal decomposition of the clay mineral dispersant itself and binding the radicals to rubber molecules, A method for producing a clay rubber composite material having properties as a vulcanization accelerator.