Chemical firm Synthomer said that despite lower demand through November and December unit margins improved due to a decline in the price of raw materials.The company cited an earlier-than-usual slowdown as the reason for sluggish demand, though it added that trading and profitability had been in line with expectations in the period following its latest update on 28 October.The FTSE 250 group reported increased demand in Asia in the fourth quarter, driven by the success of new product launches.Synthomer said it expects full-year profit for the year ended 31 December to be in the middle of the current consensus range of £80.9m to £87.3m.Synthomer shares were up 0.08% to 239.80p at 08:16 on Friday.