High heat resistance hot melt pressure sensitive adhesive is most commonly needed for automotive interiors or products that can remain inside an automobile. This is so because the temperature of air and some auto parts inside an automobile may exceed 180F. At such high temperature, most Styrenic block copolymer (SBC)-based hot melt pressure sensitive adhesives start to soften and/or flow under certain shear forces. This is because the surrounding temperature is close to the softening point of the styrene domain.
How to design or develop an extremely high heat resistant HMPSA is always a major challenge for most adhesive formulators. In recent years – many UV and/or E-beam curable HMPSAs have been developed and made available for various markets requiring high heat resistant particularly for use in both automobile and electronics.
Many adhesive users request high heat resistance of a hot melt pressure sensitive adhesive when shipping products in containers. What is the actual temperature inside a container during summer time? What is the actual temperature of an adhesive within those bonded goods? A lot of people believe it might be 160F and many feel it is 180F. To practically verify the actual temperature variations inside a container, day and night, companies can use a floating thermometer inside a container and record entire temperature history.
Most results indicated that the highest temperature inside the container is about “150F” instead of 160F to 180F. Please not that 150F is simply the temperature of air inside the container, but not the temperature of adhesive within those bonded goods, which are further packed inside various cartons and boxes. It is likely that the actual temperature of those adhesives bonded on goods is lower than 130F.
To improve the high temperature resistance of HMPSAs, more percentage of high molecular weight SBC or less tackifier is needed in the formulation. As a result, formulators need to sacrifice processibility due to the high melt viscosity of formulated adhesives.
We recommend that users of hot melt pressure sensitive adhesive look closely at the actual temperatures their package or product will need and tailor the adhesive accordingly.
For more information call or email Pierce Covert,
Glue Machinery Corporation