Investigation of unwinding noise of different industrially used self adhesive tapes

Status:

completed 03/2023

Aims:

The noise generated as a result of unwinding adhesive tapes during the packaging and shipment of products causes noise levels that pose a risk of hearing damage at workplaces across all industries. These noises are also perceived as annoying and disruptive, meaning that they also are responsible for non auditory health effects in addition to the auditory effects. In order to determine whether different adhesive tapes – which are also available as "low-noise" versions – generate different sound pressure levels, during this project, the unwinding noise of various adhesive tapes was examined under comparable laboratory conditions. Since there are no measurement methods or specifications in the machine-specific standards or elsewhere, a measurement strategy was also developed as part of this project. The main objective of this project was to quantify the sound pressure levels that occur in working areas and the differences in the sound pressure levels when unwinding different adhesive tapes. The testing focused solely on self-adhesive, single-sided, industrial products.

Activities/Methods:

The first stage of the project consisted of performing market research on the common adhesive tapes available on the market. General background knowledge of adhesive tapes was researched using various resources, including existing standards. Noise exposure at workplaces with hand-held tape dispensers and carton sealing machines was determined by means of workplace measurements carried out at member companies of the German Social Accident Insurance Institution for the Foodstuffs and Catering Industry (BGN) along with a thorough research of the MELA database – a database for measurement data on exposure to noise at work. The Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) supported the BGN with a total of three workplace measurements. For the systematic laboratory testing of the unwinding noise, it was necessary to plan and design an adhesive tape unwinding machine. This task was jointly planned and carried out in the IFA by the "Mechanical development – central production technology" team and the "Noise" section. For the purpose of a systematic investigation, a measurement method was developed and tested. The method used a measuring microphone positioned at an axial distance of 50 cm from the unwinding tape to record exclusively the unwinding noise. Thirteen different industrial adhesive tapes were able to be examined on the unwinding machine, with five rolls of adhesive tape being used per product and speed. The unwinding noise was tested at two different speeds based on existing standards concerning unwind adhesion. Sound pressure levels, sound spectra and sound level-time curves of the unwinding noise were recorded in the hemi anechoic chamber of the IFA.

Results:

The tests found sound pressure level differences of around 15 dB between the adhesive tapes examined, independently of the unwinding speed. Therefore, a significant sound pressure level difference is identified during the unwinding of various self-adhesive, single-sided, industrial adhesive tapes. Furthermore, the information from manufacturers regarding quiet unwinding or the labelling of certain products as "low-noise adhesive tapes" was not supported by a direct comparison of the products. Without a standardised measurement method or testing standard, the manufacturers specifications are not comparable and do not enable consumers to make an objective purchasing decision. As a result of this, employers have not been able to fulfil their obligation to minimise work-related health hazards up to this point. Research of the MELA database found a sound level range of around (79 ± 5) dB for packaging areas in companies. With this finding, with an exposure time of eight hours, part of the data exceeds the lower exposure action value of 80 dB set out in the Noise and Vibrations Occupational Safety and Health Ordinance (LärmVibrationsArbSchV). With quieter adhesive tapes, the level can be brought under the exposure action value. Further studies are required to expand the data basis, in order to determine the causes for the noise generation. In order for quieter adhesive tapes to be accepted, it is also important for disadvantageous properties to be taken into account, such as low adhesive strength or backing materials (sometimes described as carrier) that are not viewed as sustainable with regard to environmental protection. In the existing measured data, there are only three tapes with backing material that is not made of polypropylene (PP). Then, after an expansion of the data basis, on the basis of an exploratory factor analysis (EFA) or other statistical methods, it may be possible to create a model for the noise prediction. This is necessary in order to create product-neutral guidance documents for the purchase of low-noise adhesive tapes that are based on technical data. In addition to this, however, further data must also be made available by the manufacturers of adhesive tapes. For example, the datasheets contain no information about the release agent/coat or the bonding agent/primer. In future tests, additional factors such as temperature (of interest for packaging areas in refrigerated areas), sound directivity, the measurement position and the current measurement method should also be considered. The measurement method developed as part of this project needs to be validated further and incorporated into standardisation.

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