Development and research of a label caseine adhesive for packaging the industrial and household products

Abstract

A new composition of the environmentally friendly water-based casein adhesive glue with the increased adhesion to the substrate (glass, polyethylene terephthalate, etc.) and the improved water resistance has been developed and explored. The glue is easily washed away when labeling products that are packaged in reusable containers, but, at the same time, possesses high adhesion to different surfaces. The optimal formulation for the developed glue adhesive composition based on casein has been determined with the help of the investigated properties. The effect of the amount of a modifying additive on the dynamic viscosity at different deformation rates, the stickiness of the adhesive composition, and the hydrogen ions index (pH) has been studied. Such technological properties of the glue adhesive composition were investigated as viscosity – 170 Pa∙s; pH – 7.21; the mass share of dry residue – 38.2 %; stickiness – 58.17 a.u.; working temperature – +20…+25 °С. The optimal technological parameters for using the glue have been defined: optimal viscosity, from 130 Pa∙s to 170 Pa∙s; temperature, 25 °C, and 35 °C, respectively. The adhesive strength between a paper label and glass is 4 points, polyethylene terephthalate – 3 points. The operation properties were assessed based on the resistance of the glue adhesive composition against changes in temperature and environmental conditions, humidity, and mechanical impact. The requirements for the glue adhesive have been stated that are to be taken into consideration in its operation: resistance against the condensed and icy water and the ability of the label to be removed from the surface of the container in a washing machine at a temperature of 70–80 °C. The glue adhesive composition was examined by a SAB Miller method to assess its quality during an ice water resistance test. A copy paper method was used to assess the label gluing quality. The requirements for the glue adhesive have been defined, which should be taken into consideration in its operation (the resistance against the condensed and icy water and the removal of a label in a washing machine at a temperature of 70–80 °C with the addition of NaOH or surface-active substances).