PROJECT DESCRIPTION
BACKGROUND
Flexible food packaging usually consists of two or more thin plastic films. Sometimes metal films and metallised polyester films are also used to improve the consistency. By combining these different films, specific properties of the plastic are obtained which are suitable for different applications. Laminating adhesives are used to combine the different plastic films and metal films to the required consistency. The quantity of adhesive used varies from 1 - 5 g/m2 of packaging material, depending on the type of adhesive and application of the packaging. When producing conventionally these solventless urethane adhesives, polyols react with monomeric isocyanates, requiring the use of excessive amounts of monomeric isocyanate. This results in a concentration of monomeric isocyanates of 3 up to 50 % after the chemical reaction is completed. Due to a chemical transformation processes this monomer leads to the formation of aromatic amines, which pose a public health problem. This is of particular concern when it happens in food packaging, and there is the risk of migration into the food stuff. In the run-up to this project, a procedure was identified which could avoid this problem. This is a technique hitherto not used for the industrial urethane adhesive production. Using this technique urethane adhesives could in future be produced on an industrial scale with an isocyanate monomer contents of less than 0,1 %, thus avoiding the formation of aromatic amines. The separated monomer would be collected for re-use, thereby avoiding waste and saving resources (raw material, energy). A continuous measuring process would be developed to control the purity of the product The method would be applicable to the entire adhesive industry. Using these new solventless adhesives (monomer contents < 0.1 %) could mean the avoidance of a considerable amount of monomers per year. Using these newly-developed solventless adhesives would also reduces the use of solventborne adhesives, i.e. the emission and immission of volatile organic solvents would be reduced significantly.
OBJECTIVES
The objective of the project was to develop a solventless urethane adhesives with an extremely low content of monomeric isocyanates and to set-up a pilot plant for the production of these adhesives, and to test the results of the scale-up trials on an industrial scale. The project aimed to achieve: 1.Avoidance of migration of aromatic amines from flexible packagings into food. Using the new adhesive the risk of amine migration would be reduced and thus the health hazards would be reduced to virtually non existant risks. 2.Avoidance of workplace emissions on applying adhesives for food packaging. Using the new adhesive emission in the workplace environment would be minimised during processing. 3.Avoidance of air pollution by solvents Using newly-developed solventless adhesives the use of solvent-borne adhesives would be reduced, i.e. significantly reducing the emission and immission of volatile organic solvents. 4.Saving resources By separation and re-use, the monomeric isocyanates resources are saved. This also means a saving in energy, since the production process of isocyanates requires a lot of energy. It also minimises the use of hazardous materials. Specific objectives included: 1.Development of solventless adhesives with an extremely low monomer contents for the manufacture of food packagings on a glass pilot plant. 2.Execution of scale-up trials 3.Detailed planning, installation and testing of a pilot plant to ensure the applicability on an economically industrial scale. 4.Development of a continuous measuring process to determine and control the monomer contents of the adhesive produced.
RESULTS
As a result of the project, a completely new, high quality laminating urethane adhesive has been developed and produced. Its isocyanate content of less than 0.1%. The adhesive does not contain any organic solvents used for processing. Equipment for drying, solvent retention or post combustion is thus not required any more. Moreover, residual solvents, which sometimes remain in the packed material if conventional adhesives are used, and which may alter the odour or the taste of the packed materials, are now excluded. This method allows for the production of adhesives containing less than 0.1% reactive raw materials. The formation of the toxic aromatic amines is therefore avoided. The separated residual raw material is reused, which means that no waste is produced and resources (raw material, energy) are used economically. By using the new solventless adhesives, savings in the European Union would be approximately 700 tonnes of raw material per annum. It would also lead to a reduction in the use of solvent based adhesives, leading to a significant reduction in emissions and imissions of volatile organic solvents.As a result of the project, a completely new, high quality laminating urethane adhesive has been developed and produced. Its isocyanate content of less than 0.1%. The adhesive does not contain any organic solvents used for processing. Equipment for drying, solvent retention or post combustion is thus not required any more. Moreover, residual solvents, which sometimes remain in the packed material if conventional adhesives are used, and which may alter the odour or the taste of the packed materials, are now excluded. This method allows for the production of adhesives containing less than 0.1% reactive raw materials. The formation of the toxic aromatic amines is therefore avoided. The separated residual raw material is reused, which means that no waste is produced and resources (raw material, energy) are used economically. By using the new solventless adhesives, savings in the European Union would be approximately 700 tonnes of raw material per annum. It would also lead to a reduction in the use of solvent based adhesives, leading to a significant reduction in emissions and imissions of volatile organic solvents.
