Haze
Haze or hazyness is simply scattering of light by some medium, which results into cloudy appearance, and poorer clarity of objects when viewing through that. Medium can be anything like atmosphere, plastic film etc.
Technically haze is the percentage of light that is deflected more than 2.5 degree from the incoming light direction.
With respect to packaging films, it is very important property that helps us to evaluate film clarity. We can not measure haze value for opaque films. Normally OPP films have haze less than 3%. In case of laminating films haze value increases than OPP films.
Thin films have lower and it increases as we increase thickness of the film, keeping other factors constant. Various laminating process parameters also affect haze of the laminating films.
Glossy laminating films have less haze values and matte films have higher haze percentage. Texture of the lamination films also affects haze. If the surface is rough then it will deflect more light than a smoother one.
Companies are using commercial haze meters for testing purpose but ASTM D 1003 also allows the use of spectrophotometer provided it meets the procedure requirements accordingly.
Haze is dependent on the below factors.
Thickness of the laminating film.
Type of material.
Texture or surface finish of film.
Process parameters.