When were the first Braille playing cards produced? Which companies were involved?

This answer is proving to be difficult to find the answer for. By playing cards I assume you mean a 52-card deck which I cannot find the answer to. However, a popular playing card game from Mattel called Uno debuted in 2019 in a Braille format. Some other websites simply state that "Braille cards have been around for some time" but don't give a historic date when they debuted. Here is the reference to the Uno Braille cards:

https://www.cbsnews.com/news/uno-card-mattel-debuts-first-official-braille-deck-of-uno-cards/

The first playing cards with Braille markings were the "Kem Cards" manufactured by Kem Plastic Playing Cards Inc., Poughkeepsie, NY in the 1960s. Each card was made of plastic and featured Braille markings below the suit symbols in both the upper left and lower right of each card.

https://healthy.uwaterloo.ca/museum/VirtualExhibits/Playing%20Cards/decks/vision/index.html