Composite fibers and methods of making the same
AssigneeSpecialty Minerals (Michigan) Inc.
InventorsJohn Hockman, Harry J. Huhn, Ari-Pekka Laakso, Zhigang Chen
Life of this patent
Estimating the term…
Abstract
A method of making a composite fiber can include admixing a calcium hydroxide slake and carbon dioxide containing gas with an aqueous slurry containing fiber, wherein the addition of the slake is controlled to maintain the conductivity below saturation to thereby produce a composite fiber with improved bulking and stiffness properties when used as a filler in papermaking.
Claims21
A filler comprising composite fibers, each composite fiber comprising mineral attached to a fiber, wherein the mineral is at least about 90 wt % based on the total weight of the composite fiber, the uncoated fiber has an average length of less than 300 μm, and the composite fiber has a Horiba d90 of at least 10 μm.
A method of making composite fibers, comprising:
- preparing a calcium hydroxide slake by diluting lime in water;
- admixing an aqueous fiber slurry with dilution water in a reactor;
- adding the calcium hydroxide slake and a CO2 containing gas into the reactor containing the aqueous fiber slurry admixed with the dilution water to precipitate calcium carbonate onto the fiber;
- and
- continuing a flow of the CO2 containing gas into the admixture after the addition of the calcium hydroxide slake has started until a pH of 7.0 is reached, wherein:
- the calcium hydroxide slake is added at a rate to maintain a target conductivity that is 50% to 80% of saturation and the target conductivity is maintained until the addition of the calcium hydroxide slake is complete,
- the fiber slurry comprises fibers having a length of 300 μm or less, and
- the fiber slurry comprises an amount of fiber such that fiber content in the composite fibers is 10 wt % or less based on the total weight of the composite fibers.
Dependencies are inferred from the claim text.