JP2019026918A - Conjugate of metal and fluororubber, and bonding method thereof - Google Patents

Abstract

To provide a conjugate formed by bonding a metal to a fluororubber without using a primer; and to provide a bonding method thereof.SOLUTION: A bonding method of a metal to a fluorine-containing material to be used includes steps of: forming a hydroxide of a metal on the surface of the metal by immersing/contacting a metal into/with test water at 250°C or lower; and forming the fluorine-containing material on the surface of the metal. A conjugate of the fluorine-containing material and the metal to be used contains the metal, the hydroxide of the metal positioned on the surface of the metal, and the fluorine-containing material positioned on the surface of the hydroxide of the metal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a joined body of metal and fluororubber and a joining method thereof.

  Conventionally, a primer has been used as an adhesion between a metal substrate and fluororubber or perfluoroelastomer (Patent Document 1).

Japanese Unexamined Patent Publication No. Sho 63-112673

However, since the primer has low heat resistance, the adhesive strength is reduced by decomposition or alteration. Moreover, a high technique is required for uniform application. For this reason, there is a problem in the stability of quality.
Therefore, the subject of this application is providing the joining body which joined the metal and fluororubber, and its joining method, without using a primer.

In order to solve the above problems, a step of immersing or contacting a metal in test water at 250 ° C. or less to form a hydroxide of the metal on the surface of the metal, and a step of forming a fluorine material on the surface of the metal And a bonding method of a metal containing fluorine and a fluorine material.
In addition, a joined body of a fluorine material and a metal including a metal, a hydroxide of the metal located on the metal surface, and a fluorine material located on the surface of the metal hydroxide is used.

  According to the joined body and the joining method of the present invention, it is possible to provide a joined body obtained by joining a metal and fluororubber without using a primer and the joining method thereof.

Flow chart explaining the process of the embodiment (A)-(d) Sectional drawing explaining the process of embodiment SEM image of the surface of an untreated aluminum substrate and an aluminum substrate (Example 3) after being immersed in 90 ° C. test water for 5 hours EDX spectrum diagram of an untreated aluminum substrate and an aluminum substrate (Example 3) after being immersed in 90 ° C. test water for 5 hours Aluminum after exfoliating fluororubber (ternary peroxide vulcanization) and perfluoroelastomer 90 ° in an aluminum substrate (Examples 3 and 7) immersed in test water at 90 ° C. for 5 hours SEM image of substrate and EDX spectrum

Hereinafter, one embodiment will be described. It is one example and the invention is not limited to the following.
(Embodiment)
The process of the embodiment is shown in FIG. Each step will be described with reference to FIGS.

<Metal plate 10>
The metal material of the metal plate 10 is preferably as follows. Metals that fill all are preferred.

(A) The standard electrode potential is lower than the potential of the reduction reaction of dissolved oxygen (about + 0.4V), and when there is no dissolved oxygen, the potential of the reduction reaction of water (−0.83V) Be a low-potential.
(B) The surface passive film and the internal metal substance are dissolved with a weak acid having a pH of about 3 to 4 or a weak base having a pH of about 8 to 10.

(C) The dissolved metal ion is hydrolyzed to produce a hydroxide.
(D) Do not corrode uniformly near the potential of the oxygen reduction reaction at the pH-potential diagram of pH 7 or the potential of the water reduction reaction.

  Specific examples include simple metals such as aluminum, magnesium, zinc, manganese, and beryllium, and alloys mainly composed of them. Hereinafter, aluminum will be described, but the same applies to simple metals of magnesium, zinc, manganese, and beryllium or alloys mainly composed of them.

(1) Heating step (FIG. 2 (a))
The test water 12 is heated by the heater 16. As the test water 12, ultrapure water manufactured by Kanto Chemical Co., Inc. can be used.

  The test water 12 needs an electric resistance value of 10 MΩ · cm or more and 18.2 MΩ · cm or less. Distilled water and ion-exchanged water are not possible because they do not satisfy the electrical resistivity.

  When the electric resistance value of the test water 12 is low, the dissolution reaction (pitting corrosion generation) of the metal plate 10 (hereinafter referred to as aluminum) is used as an anode, and the reduction reaction of oxygen molecules that occurs at a trace impurity interface in the aluminum is used as a cathode. It is not good because no battery reaction occurs.

Further, it is not good because acid and hydroxide are not generated by hydrolysis reaction between aluminum ions and water generated by the battery reaction.

In addition, chlorine ions, nitrate ions, silicate ions, hypochlorite ions, or phosphate ions that cause pitting corrosion with an appropriate hole diameter that is considered to cause the anchor effect is water with an appropriate concentration. Also good. In addition, there is no effect in the grade of purified water with low purity.
The heating temperature is also effective from normal temperature to boiling water, and even test water 12 that has been raised to 100 ° C. or higher by an autoclave. When the temperature is normal, the immersion time increases, and when the temperature is high, the effect is shorter. There is no particular limitation on the heating method, and a hot plate, a mantle heater, or a beaker-type heater may be used.

(2) Immersion process (Fig. 2 (b))
The metal plate 10 is immersed in the heated test water 12.
The test water 12 used needs an electric resistance value of 10 MΩ · cm or more. The immersion time varies depending on the temperature of the test water 12. In the case of 20 ° C., 280 hours, in the case of 40 ° C., 50 hours, and in the case of 90 ° C., about 2 hours are required. It is preferable to stir during the immersion and keep the heating constant.

<Boehmite treatment>
In addition, there is usually a boehmite treatment with a surface treatment of aluminum. Differences from this will be described below.
The boehmite treatment is a reaction in which the aluminum surface expands by reacting with high-temperature water and forms a hydrated oxide film (AlOOH) having rough irregularities with a period of about 200 nm in the horizontal direction of the substrate.

In the case of immersion of the test water 12 of the embodiment, a local battery reaction occurs, and a nano-sized rod-shaped substance is stacked due to a reaction in which aluminum is dissolved and aluminum hydroxide (Al (OH) ₃ ) is generated. The structure has fine irregularities with a period of 10 nm to 100 nm. This structure has many gaps and is stacked from the surface to a depth of 1 μm to 5 μm.

Therefore, since the adhesive is finer and deeper than the boehmite treatment and enters many gaps, a stronger anchor effect can be expected.
The immersion is not essential. For example, the test water 12 may be continuously sprayed on the surface of the metal plate 10. Or you may keep spraying the vapor | steam of the test water 12 on the surface of the metal plate 10. FIG.

(3) Molding process (FIG. 2 (c))
The metal plate 10 and the heat-resistant film 17 are set as a set on the mold 19, the compound of the fluoro rubber 13 is placed in the lower mold heated to 180 ° C., and the upper mold heated to 180 ° C. is pressed (primary vulcanization). As a result, the fluororubber 13 is formed on the metal plate 10. As a result, the joined body 15 of the fluororubber 13 and the metal plate 10 shown in FIG. The molding conditions were press molding at 180 ° C. for 10 minutes. The heat resistant film 17 is for evaluation described below.

As the fluororubber 13, a fluororubber composition having a constitution mainly composed of a structural unit derived from vinylidene fluoride, a structural unit derived from hexafluoropropylene, and a structural unit derived from tetrafluoroethylene can also be used. It can be applied to all fluoro rubbers.
A perfluoroelastomer containing a constitutional unit mainly derived from a constitutional unit derived from tetrafluoroethylene, perfluoro (alkyl vinyl ether) or perfluoro (alkoxyalkyl vinyl ether) can also be used.

In the mold 19, the fluororubber 13 is pressed against the metal plate 10. However, the fluororubber 13 and the metal plate 10 can be bonded without pressing.
(4) Secondary vulcanization The joined body 15 is taken out from the mold 19 and subjected to secondary vulcanization with an electric furnace. The heat treatment was performed at 230 ° C. for 10 hours. Secondary vulcanization may be performed under normal conditions.

<Example>
The sample of the Example was produced below and evaluated. Table 1 shows the conditions and results. Matters that do not describe conditions are the conditions described in the above embodiment.

(1) Heating process Ultrapure water (test water 12) was added to a beaker, and the temperature was adjusted to a predetermined temperature with a hot stirrer (heater 16). Table 1 shows the temperature and time.

(2) Immersion step A 60 mm × 25 mm × 2 mm A5052 aluminum substrate (metal plate 10) fixed with a jig was immersed in the solution (test water 12) being stirred by a stir bar for a predetermined time.
(3) After dipping in the molding process, the substrate is naturally dried, and the substrate (metal plate 10) is placed in the mold 19, and a predetermined amount of ternary peroxide vulcanization or perfluoroelastomer is added as the fluoro rubber 13. Under the conditions of vulcanization temperature and vulcanization time shown in No. 1, a sample of the bonded body 15 of rubber and aluminum substrate was press-molded.

Viton (trademark of Chemers Co., Ltd.) was used as the fluororubber, and Kalrez (trademark of DuPont Co., Ltd.) was used as the perfluoroelastomer.
(4) Secondary vulcanization Secondary vulcanization was performed under the conditions shown in Table 1.
<Comparative example>
The sample of the comparative example was produced and evaluated below. Table 1 shows the conditions and results. There are a comparative example in which the same steps as in the examples were performed under different conditions, and a comparative example in which some steps were not performed.

Further, unlike the other examples, there are also Comparative Examples 3 and 6 in which primer is applied. In this method, the surface of the aluminum base material was used as a primer treatment, and a solvent-based primer was soaked into the waste cloth and rubbed onto the aluminum substrate by hand, and dried at room temperature for about 1 hour.
Primer treatment was performed with Chemlock 607. Chemlock 607 is a primer for adhesion between metals and rubbers manufactured by Road Corporation, and is a solution having a solid content concentration of 6.2 to 6.8 wt% composed of several types of silane coupling agents, alcohol, and toluene.

<Evaluation method>
After the secondary vulcanization, the heat-resistant film 17 was removed, and a gap was provided between the aluminum and the fluororubber 13 so that it could be attached to a jig of a 90 ° peel tester. 90 ° peeling between the rubber and the aluminum substrate was performed with a Tensilon (tensile tester), and the peel strength was measured. About test piece preparation and the test method, it carried out according to JISK6256-2. The Tensilon tensile tester is a tensile tester manufactured by Shimadzu Corporation (model number AGS-X).

Some of the rubber-destructed ones are those in which the rubber itself has been destroyed and the bonding is strong.
What peeled at the interface is peeled off at the interface between the rubber and aluminum, and the bond is weak.
Those having a peel strength of 0 were those which were not vulcanized and bonded during primary vulcanization (during press molding).

<Pass / fail>
A peel strength of 25 N / mm or more was accepted. This is because the numerical value is necessary for bonding the aluminum substrate and the fluorine-based rubber to which this bonding technique can be applied.

<Discussion>
(1) From the results in Table 1, the processing conditions for aluminum are 65 ° C. to 90 ° C., and the processing time is 1 hour to 5 hours.
(2) Comparative Examples 3 and 6 are primer-treated, but have significantly different peel strengths. It is necessary to optimize the relationship between the primer agent, metal and rubber. Moreover, since primer processing itself is required, it deviates from the subject of this application.

(3) In Examples 1 to 3 and Examples 4 to 7, bonding is possible without depending on the type of fluororubber.
(4) With respect to the primer treatment, the method of the embodiment allows bonding regardless of the type of rubber. In the method of the embodiment, it is not necessary to optimize the type of metal and rubber.

<Photograph observation>
FIG. 3 shows SEM images of the untreated aluminum substrate and the surface of the aluminum substrate (Example 3) after being immersed in 90 ° C. test water for 5 hours. It can be seen that rod-like (fibrous) substances having a diameter of 10 nm to 70 nm and a length of 100 nm to 300 nm are stacked on the surface of the aluminum and formed deep. From this, it can be considered that aluminum and rubber are bonded due to the anchor effect. In addition, it can be confirmed that a circular shape is present in the low-magnification SEM image after immersion of aluminum in test water 12 (part surrounded by a dotted line). The bun has a structure in which thin films are stacked, and the composition is the same as the surrounding surface, and there is about one in an area of 1500 μm ² . The size is 1 μm to 15 μm in diameter.

  FIG. 4 shows an EDX spectrum of the entire upper SEM image for an untreated aluminum substrate and an aluminum substrate (Example 3) after being immersed in 90 ° C. test water for 5 hours, and obtained from the EDX spectrum. Table 2 shows the elemental composition at a depth of 1 μm from the surface.

From the results of FIG. 4 and Table 2, it is considered that the abundance of oxygen atoms is increased and hydroxides or oxides are generated. According to the literature (Light Metals Vol. 56 No. 2 (2006) 82) It is considered to be aluminum hydroxide.

  FIG. 5 shows 90 ° peeling of fluororubber (ternary peroxide vulcanization) and perfluoroelastomer from an aluminum substrate (Examples 3 and 7) immersed in test water 12 at 90 ° C. for 5 hours. The SEM image of the aluminum substrate after separating is shown. Table 3 shows the results of elemental analysis at a depth of 1 μm from the surface by EDX over the entire SEM image.

It can be confirmed that rubber is present in a portion surrounded by a dotted line in FIG. 5 and Table 3, since a large amount of carbon and fluorine were detected, fluororubber (three-dimensional peroxide vulcanization) and perfluoroelastomer were treated with test water 12 even after 90 ° peeling. It was clarified not only from the SEM image but also by elemental analysis that it remained on the substrate.

Based on these results, the improvement of the adhesion between the metal and the fluorine-based rubber is due to the rubber entering the gap between the rod-shaped aluminum hydroxides having a diameter of 10 nm to 70 nm and a length of 100 nm to 300 nm by immersion of the test water 12. This is probably due to the anchor effect.
(as a whole)
Although described with aluminum, the same applies to simple metals such as magnesium, zinc, manganese, and beryllium or alloys mainly composed of them. Further, although there is a difference in the time required for immersing the test water 12, it is not affected by the purity of aluminum. Any metal that can form a nanosized rod-like metal hydroxide with a surface of several μm in the test water 12 can be used.

The joining method of a metal and a fluorine material and the joined body of a metal and a fluorine material of the present invention can be used for joining various metals and rubber.
Available at.

DESCRIPTION OF SYMBOLS 10 Metal plate 12 Test water 13 Fluoro rubber 15 Joined body 16 Heater 17 Heat resistant film 19 Mold

Claims (8)

Immersing or contacting a metal in test water at 250 ° C. or lower to form a hydroxide of the metal on the surface of the metal;
Forming a fluorine material on a surface of the metal, and joining the metal and the fluorine material. The method for joining a metal and a fluorine material according to claim 1, wherein the electric resistance value of the test water is 10 MΩ · cm or more and 18.2 MΩ · cm or less. The method for joining a metal and a fluorine material according to claim 1 or 2, wherein the hydroxide has a thickness of 1 µm to 5 µm. The method for joining a metal and a fluorine material according to any one of claims 1 to 3, wherein the hydroxide is a fiber having a diameter of 10 nm to 70 nm and a length of 100 nm to 300 nm. The method for joining a metal and a fluorine material according to any one of claims 1 to 4, wherein the surface of the hydroxide has a circular shape having a diameter of 1 µm to 15 µm. Metal,
A hydroxide of the metal located on the surface of the metal;
A joined body of a fluorine material and a metal including a fluorine material located on a surface of the metal hydroxide. The joined body of fluorine material and metal according to claim 6, wherein the metal hydroxide has a thickness of 1 µm or more and 5 µm or less. The joined body of a fluorine material and a metal according to claim 6 or 7, wherein the metal hydroxide is fibrous.