The gist of that is true, But neither is the CFC regulation story as simple as that.

It's not that the patents were running out, but by the 1980s third world producers, e.g. in India, were becoming proficient at making the well-known CFCs. That was going to eat into the profits of the major US/European producers. On the other hand, the replacement chemicals were considerably more difficult to manufacture and there were some patent issues, at least on mfg processes if not the chemicals themselves.

But, the ozone concern was not driven simply by protectionism. When the link between CFCs and ozone depletion first became known in the early to mid 1970s, the big chemical companies were very opposed to taking action. At that point, the third world producers were not yet a big threat, and, they didn't have the replacement HCFCs developed.

By the mid 1980s, the time of the Montreal Protocol, their market share was slipping and they saw that they'd be able to recapture it with HCFCs, and so the first-world chemical industry went from opposition to support of an international treaty restricting CFCs.

There is no question that the shifting view of the chemical corps had an impact on the negotiations. On the other hand, it clearly wasn't the fundamental reason for pushing CFC restrictions in the first place -- that had been going on for well over a decade even when Dow, ICI, etc were strongly opposed.

We often call this a "baptists and bootleggers" effect -- i.e., both supported Prohibition, but for very different reasons.

David Vogel has written extensively on this phenomenon in regulation.