Polyvinyl alcohol membrane and preparation method thereof as well as polarizing film prepared by polyvinyl alcohol membrane
A polyvinyl alcohol-based film, polyvinyl alcohol technology, applied in optics, optical elements, polarizing elements, etc., can solve the problems of inconsistent thickness, fractured dyeing, unevenness, etc., to reduce uneven drying degree, uniform volatilization speed, Guaranteed effect of optical performance
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Embodiment 1
[0048] This implementation discloses a polyvinyl alcohol-based film. The raw materials for preparation include the following components in parts by mass: 25-33% polyvinyl alcohol, 9-18% plasticizer, 1% surfactant and antioxidant Below, the degree of polymerization of polyvinyl alcohol is 1500-3000, the degree of alcoholysis is 97-100mol%; the plasticizer is a polyhydroxy compound, preferably glycerin, the purity is ≥ 99.5%, and the antioxidant is selected as 1010 / 168 as 1:1 Compositions. This polyvinyl alcohol-based film is an initial film or an original film for producing a polarizing film.
[0049] This embodiment also provides a method for preparing a polyvinyl alcohol-based film, the steps are as follows:
[0050] Step 1, mixing, plasticizing, defoaming: After further complete alcoholysis, purification and washing of polyvinyl alcohol raw materials, put them into a twin-screw extruder for mixing and plasticizing with plasticizers, surfactants and antioxidants , defoaming...
Embodiment 2
[0058] The difference between this embodiment and embodiment 1 is that
[0059] Step 4, secondary drying: send the film peeled off in step 3 to 20 drying rollers for further dehydration and drying, and the surface temperature of the drying rollers is controlled at 85°C. From the first drying roll to the end of the last drying roll, the drying temperature of the roll surface decreases gradually, and the temperature difference between adjacent rolls is equal to 1°C. The speed of the drying roll is: the speed of the first half of the drying roll is constant; the speed of the second half of the drying roll gradually increases, and between adjacent drying rolls, the speed of the faster drying roll is equal to 105% of the speed of the slower drying roll. Since the number of drying rollers in this scheme is 20, the speed of the first 10 drying rollers is 5m / min, and the speed of the 11th drying roller is increased on the basis of 5m / min, that is, 5.25m / min, and the subsequent ones in...
Embodiment 3
[0064] Step 4, secondary drying: send the film peeled off in step 3 to a plurality of even-numbered drying rollers for further dehydration and drying, and the surface temperature of the drying rollers is controlled at 80°C. From the first drying roll to the end of the last drying roll, the drying temperature of the roll surface decreases gradually, and the temperature difference between adjacent rolls is equal to 1°C. The speed of the drying roll is: the speed of the first half of the drying roll is constant; the speed of the second half of the drying roll gradually increases, and between adjacent drying rolls, the speed of the faster drying roll is less than 105% of the speed of the slower drying roll.
[0065] Step 5, three times of drying: the film leaving the last drying roller in step 4 is sent to the air flotation drying box for suspension drying, and the drying temperature is 125 °C;
[0066] Step 6: Humidity adjustment: Before the membrane in step 5 leaves the air flot...
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Abstract
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