LONDON — The Valentine’s Day debut of “Fifty Shades of Grey” is providing a boon to an industry that rarely benefits from a big-brand film franchise: sex toys.

With the screen version of the erotic novel hitting theaters this weekend, purveyors of official merchandise are already experiencing a rush of demand in a market where only about 15 percent of products are branded.

“You have this recognizable brand for the mass of the population with the amount of publicity that ‘Fifty Shades’ has gotten,” said Marty Brochstein, senior vice-president of industry relations at the International Licensing Industry Merchandisers’ Association. “It’s a natural thing that it would attract attention and that it would bring a new element to this product category.”

Sales in Britain’s sex-toy industry are due to rise 25 percent to about $77 million in the month leading up to Feb. 14 compared with the same period a year earlier, according to Lovehoney Ltd., Britain’s biggest online retailer of erotic merchandise.

Lovehoney, the owner of global rights to “Fifty Shades” pleasure products, had a record sales day last week, up 60 percent as it handled more than 9,000 orders.