Greenock-based BPI saw volumes rise by two per cent to 154,000 tonnes in the six months ended June 30, driven by the acquisition of Flexfilm, increased capacity in Europe and recovery in the UK construction sector.
But sales at the firm, which manufactures films and packaging for the agriculture, construction and retail sectors, dipped narrowly to £281.1 million after currency movements were factored in.
The interim results came as BPI chairman Cameron McLatchie warned he sees "no upside" for the business in the event of a Yes vote in next month's referendum.
BPI said profits had improved in the UK by 25 per cent and Europe by nine per cent in local currency. The combined £2 million earnings-gain here was offset by a "small loss" of £0.6 million in North America, caused by the delay in replacing a new manufacturing line.
Chief executive John Langlands said a strong second quarter helped the firm overcome the effects of a late start to the UK agricultural season and stock carried over from last year, meaning silage volumes across the UK and Europe were broadly in line with the previous year. He said the progress has BPI on course for a "good outcome for the year as a whole".
The improvement in the firm's underlying profit performance in the UK and Europe led BPI to declare an interim dividend of 5p, up from 4.5p in 2013.
Mr Langlands said: "It is a good set of results. We have made good progress in the UK, with another strong performance in Europe.
"Our UK business improved very much on the back of better volumes, including an acquisition made the previous year, and recovery in our construction businesses, and we benefited from operational improvements including the benefits from capex. Our European business performed well, with an increase in volumes both from our silage and industrial-products base. We suffered in North America where we saw the delay in the delivery of a new line."
The update from BPI came as Mr McLatchie warned a Yes vote in the referendum would be bad for business.
Mr McLatchie and Mr Langlands were among the 130 Scottish business leaders who signed a letter this week warning about the risks and uncertainty presented by independence. It was countered by a letter signed by 200 pro-independence businesspeople including Clyde Blowers' boss Jim McColl.
Asked if he was surprised the vote has created division within the business community, Mr McLatchie said: "It depends on how you define the business community. When you look at the spread of large businesses who trade in Scotland and across the UK who have come out against it, you get a more representative view of how business feels about it. Take one large business of the 133 who signed against it and their turnover and employees would dwarf the entire assembly in favour of it.
"The only thing business sees here is uncertainty and risk, and we do not deal in uncertainty risk. There are uncertainties around currency, regulation, administrative costs and pension. There is no upside we can see for our business or those based in Scotland which trade extensively south of the Border."
Mr McLatchie said BPI has not made any provisions for a Yes vote but revealed the uncertainty is influencing its investment intentions for its plants in Scotland.
Shares in BPI closed up 27p or 4.62 per cent, at 612p.