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US 5,587,404 AGranted
Gels with thermotropic properties
AssigneeBASF SE
InventorsHubertus Kroner, Ekkehard Jahns, Manfred Mielke
Life of this patent
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Abstract
Gels for thermotropic layers, obtainable by irradiation of a mixture comprising a) an uncrosslinked polymer, b) monomers capable of free-radical polymerization and c) water or an organic solvent or mixtures thereof, with high-energy light.
Claims7
A gel for thermotropic layers, obtained by irradiation of a mixture comprising
- a) an uncrosslinked polymer selected from the group consisting of poly-N-vinylcaprolactam, copolymers of N-vinylcaprolactam containing at least 20% by weight of N-vinylcaprolactam and polyvinyl ethers, said uncrosslinked polymer having thermotropic properties such that a 10% by weight solution of this polymer in water or an organic solvent or mixtures thereof brings about, in a switching range covering less than 20.degree. C., a change in the transmission of light at a wavelength of 600 nm and at a path length of 10 mm such that less than 50% of the incident light is transmitted at temperatures above the switching range and at least 70% of the incident light is transmitted below the switching range,
- b) monomers capable of free-radical polymerization and
- c) water or an organic solvent or mixtures thereof, with high-energy light.
A process for preparing gels with thermotropic properties, which comprises irradiating a mixture comprising
- a) an uncrosslinked polymer selected from the group consisting of poly-N-vinylcaprolactam, copolymers of N-vinylcaprolactam containing at least 20% by weight of N-vinylcaprolactam and polyvinyl ethers, said uncrosslinked polymer having thermotropic properties such that a 10% by weight solution of this polymer in water or an organic solvent or mixtures thereof brings about, in a switching range covering less than 20.degree. C., a change in the transmission of light at a wavelength of 600 nm and at a path length of 10 mm such that less than 50% of the incident light is transmitted at temperatures above the switching range and at least 70% of the incident light is transmitted below the switching range,
- b) monomers capable of free-radical polymerization and
- c) water or an organic solvent or mixtures thereof, with high-energy light.
A gel for thermotropic layers, obtained by irradiation of a mixture comprising
- a) an uncrosslinked polymer selected from the group consisting of polyvinyl ethers, poly-N-vinylcaprolactam and copolymers of N-vinylcaprolactam containing at least 20% by weight N-vinylcaprolactam,
- b) monomers capable of free-radical polymerization and
- c) water or an organic solvent or mixtures thereof, with high-energy light.
Dependencies are inferred from the claim text.