Foam treatment of air permeable substrates
First Claim
1. A process for the application of a treatment agent to an air permeable substrate which method comprises,(i) forming a liquid bath comprising said treatment agent,(ii) forming a foam from said liquid bath,(iii) applying said foam to a first side of said substrate,(iv) causing said foam to permeate the interstices of said substrate by the application of a pressure gradient thereacross,(v) and removing foam liquid from a second side of said substrate, characterised in thatthe foam is applied in an excess of the foam transit liquid content of the sheet material such that the amount of agent taken up by the substrate is dependent on the concentration of the agent in the foamed liquid bath and not by the volume of the liquid bath applied in foam form,whereby the amount of agent taken up by said substrate is substantially independent of the initial water content of the substrate,wherein the treatment agent is selected from the group consisting of dyes, bleaching agents and finishing agents to be incorporated in the sheet material.
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Accused Products
Abstract
This invention relates to the application of a treatment agent to an air permeable substrate by forming a foam of a liquid containing or constituting the treatment agent and applying the foam to the substrate and causing or allowing the foam to transit the substrate and to be removed from the other side thereof in which process the foam is applied in an excess defined as a ratio of the foam transit liquid content of the material in which case the amount of treatment agent taken up by the substrate will be dependent solely on the concentration of the agent within the foam and not by the volume of the foam applied and further the amount of agent taken up by the substrate is substantially independent of the initial water or liquid content of the substrate.
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Citations
15 Claims
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1. A process for the application of a treatment agent to an air permeable substrate which method comprises,
(i) forming a liquid bath comprising said treatment agent, (ii) forming a foam from said liquid bath, (iii) applying said foam to a first side of said substrate, (iv) causing said foam to permeate the interstices of said substrate by the application of a pressure gradient thereacross, (v) and removing foam liquid from a second side of said substrate, characterised in that the foam is applied in an excess of the foam transit liquid content of the sheet material such that the amount of agent taken up by the substrate is dependent on the concentration of the agent in the foamed liquid bath and not by the volume of the liquid bath applied in foam form, whereby the amount of agent taken up by said substrate is substantially independent of the initial water content of the substrate, wherein the treatment agent is selected from the group consisting of dyes, bleaching agents and finishing agents to be incorporated in the sheet material.
Specification