JPS59217735A - Regeneration process for fluororubber - Google Patents

Abstract

PURPOSE:To obtain a regenerated fluororubber usable at a high temperature without causing hardening, and having excellent properties, by treating a fluororubber with an amine, and stirring and washing the treated rubber in a solvent capable of swelling the fluororubber or reacting with the amine. CONSTITUTION:Crushed waste fluororubber is treated with an amine, and stirred and washed in a solvent capable of swelling the fluororubber (preferably an organic solvent such as alcohol, ketone, ester, ether, cyclohexanone, etc., organic acid, or water) or a solvent reactive with the amine (preferably ketone or organic acid). The amount of solvent for washing the rubber is preferably 2-3pts.wt. per 1pt. of the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recycling fluororubber that can be used at high temperatures and can yield recycled rubber with excellent performance.

Fluororubber has excellent performance and is widely used, so it is desired to effectively recycle waste rubber. Although fluororubber is depolymerized by amines, amines also promote the crosslinking reaction of fluororubber at high temperatures. Therefore, the range of application of recycled rubber treated with amines is limited because it cures at high temperatures. In this way, recycled rubber that has lost the excellent performance of fluororubber has little value and has not been effectively reused as a resource.

In view of the above circumstances, the present invention aims to provide a useful fluororubber recycling method.

The gist of the present invention is a fluororubber regeneration treatment method that is characterized in that, in the fluororubber regeneration treatment using an amine, the recycled rubber after the amine treatment is stirred and washed in a fluororubber swelling or amine-reactive solvent. It is something.

According to the method of the present invention, it is possible to obtain recycled rubber that does not harden when used at high temperatures and has excellent performance, which has been difficult in the past.

The present invention will be explained in detail below.

The recycled rubber used in the present invention is recycled by depolymerizing waste fluororubber with an amine.

Various fluorocarbon waste rubber recycling methods using amines can be selected, but
An effective and safe method is to crush waste rubber and immerse it in alcohol or other fluororubber swelling medium in which a noalkyl monoamine such as laurylamine is dissolved.

In the present invention, examples of rubber swelling solvents that can be used for cleaning reclaimed rubber include alcohols, ketones, esters, ethers, cyclohexanone, organic acids, and water.

Further, examples of amine-reactive solvents include ketones and organic acids.

Among these, particularly preferred are Monoke alcohol and ketones, specifically methanol, MEK (methyl ethyl ketone), and acetone. Acetic acid is easily used as the organic acid.

In the method of the present invention, the fluororubber is swollen to loosen bonds and washed with a solvent that dissolves the amine or reacts with the amine, so almost no amine remains in the recycled rubber separated from the solvent. .

It is preferable to use the solvent for cleaning rubber in an amount 2 to 3 times the weight of the rubber. Although the cleaning effect can be seen even if the solution is left immersed, it is best to stir it appropriately. The stirring work depends on the condition of the recycled rubber, but in the case of powdered rubber, it takes 1 to 3 hours at room temperature, on average 2 hours.
Time is enough.

The reclaimed rubber treated by the method of the present invention does not show any hardening phenomenon due to amines, and can be mixed with about 50% new rubber i and vulcanized for wide use.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Waste fluorocomb comb frozen and crushed to a size of 60 mesh was immersed in a 0.1 mol laurylamine/1 methanol solution for 48 hours to obtain recycled rubber. Methanol in an amount three times the weight of the rubber is added to the recycled rubber, and the mixture is stirred and washed at room temperature for 2 hours. Next, the rubber powder is vacuum dried to obtain recycled rubber.

A rubber sheet obtained by blending this recycled rubber with new rubber at a ratio of 2:8.3 and vulcanizing it in a normal manner is
It showed excellent performance in a 7-day heat aging test at °C. That is, it is clear from FIG. 1 that the 100% modulus and elongation rate are not significantly different from the values of the new rubber, and there is no difference in performance.

Figure 2(a) shows the 25% elongation stress of an unvulcanized recycled rubber sheet, and the recycled rubber cleaned by the method of the present invention has
While it shows the stress before amine treatment even at 230 °C,
It can be seen that the unwashed recycled rubber (those subjected to only the first stage dipping treatment) increases stress as the temperature increases and hardens rapidly at 230°C. This means that while unwashed rubber has a limited range of use, recycled rubber that has been washed can withstand high-temperature use and can be reused over a wide range of areas.

Example 2 The same treatment as in Example 1 was performed except that acetone was used as the cleaning solvent. In this case as well, the recycled rubber
As shown in FIG. 2(b), the 5% stress is not much different from that before the amine treatment. This shows that useful recycled rubber can be obtained even after washing with acetone.

Example 3 Recycled rubber lK treated with amine in the same manner as Example 1
g, add 0.1 mol of acetic acid/-0 aqueous solution 11]
Stir and wash for one hour. Although the amine removal effect was observed, it was difficult to completely remove water.

[Brief explanation of drawings]

Figure 1 shows the case of washing with methanol, and Figure 1 (
a) I-i, recycled rubber blend ratio and 100% after heat aging
The relationship between modulus and heat-aged contact tension is also shown in Figure 1 (
b) shows the relationship between the recycled rubber blend ratio, the elongation rate after heat aging, and the hardness after heat aging. FIG. 2(a) shows the 25% elongation stress in the post-heat aging test of unvulcanized recycled rubber sheets washed with methanol and FIG. 2(b) with acetone. Agent Patent attorney Masaharu Yamagami pOloy ]Y4 =< -1vo[@qb 1
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Claims (3)

[Claims] (1) A fluororubber regeneration treatment method using an amine, which comprises stirring and washing the recycled rubber after the amine treatment in a fluororubber-swelling or amine-reactive solvent. (2) The fluororubber swelling solvent is alcohol,
The method for regenerating fluororubber according to claim 1, wherein organic solvents such as ketones, esters, ethers, and cyclohexanone, or organic acids, and water are used. (3) The fluororubber regeneration method according to claim 1, wherein the amine-reactive solvent is a ketone or an organic acid.