Method and system for making light-blocking articles

Abstract

A foamed, opacifying element having a target light blocking value (LBV T ) and a target porous substrate is prepared by determining the light blocking value (LBV S ) of the target porous substrate; calculating the LBV T-S difference; choosing a foamable aqueous composition; determining a dry coating weight for the chosen foamable aqueous composition (when foamed); and using the dry coating weight to form the single dry opacifying layer as the only layer disposed on the target porous substrate, such that the single dry opacifying layer has light blocking value that is equal to LBV T-S , ±10%. The chosen foamable aqueous composition comprises the essential components (a) through (e) described herein. The desired foamable aqueous composition can be chosen from a set of similar compositions to achieve the desired LBV T with the noted target porous substrate using suitable mathematical formula relating dry coating weight to light blocking value and a suitable data processor.

1 . A method for providing a foamed, opacifying element having a target light blocking value (LBV T ) and comprising a target porous substrate having a first supporting side and an opposing second supporting side, the method comprising:
 choosing a target porous substrate;   choosing a target light blocking value (LBV T );   determining a light blocking value (LBV S ) of the target porous substrate;   calculating LBV T-S  as a difference between LBV T  and LBV S ;   choosing a foamable aqueous composition;   using a mathematical formula to obtain a dry coating weight for a single dry opacifying layer derived from the chosen foamable aqueous composition; and   using the dry coating weight to form the single dry opacifying layer as the only layer disposed on the first supporting side of the target porous substrate, such that the single dry opacifying layer has light blocking value that is equal to LBV T-S , +10%,   wherein the chosen foamable aqueous composition has at least 35% solids and up to and including 70% solids, and comprises:   (a) at least 0.05 weight % and up to and including 15 weight % of porous particles, each porous particle comprising a continuous polymeric phase and a first set of discrete pores dispersed within the continuous polymeric phase, the porous particles having a mode particle size of at least 2 μm and up to and including 50 μm and a porosity of at least 20 volume % and up to and including 70 volume %, and the continuous polymeric phase having a glass transition temperature greater than 80° C. and comprising a polymer having a viscosity of at least 80 centipoises and up to and including 500 centipoises at a shear rate of 100 see in ethyl acetate at a concentration of 20 weight % at 25° C.,   (b) at least 20 weight % of a binder material;   (c) at least 0.0001 weight % of one or more additives comprising at least one surfactant;   (d) water; and   (e) at least 0.001 weight % of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs predetermined electromagnetic radiation,   all amounts being based on the total weight of the chosen foamable aqueous composition, and wherein the chosen foamable aqueous composition can be foamed to provide a foamed aqueous composition having a foam density of at least 0.1 g/cm 3  and up to and including 0.5 g/cm 3 .   
     
     
         2 . The method of  claim 1 , wherein the foamed, opacifying element has a luminous reflectance that is greater than 40% as measured by the Y tristimulus value. 
     
     
         3 . The method of  claim 1 , wherein the target porous substrate comprises a porous textile web, porous polymer film, porous cellulosic material, porous ceramic material, or porous glass material. 
     
     
         4 . The method of  claim 1 , wherein the chosen foamable aqueous composition comprises a tinting colorant, a flame retardant, an antimicrobial agent, or a flocking agent as a (c) additive. 
     
     
         5 . The method of  claim 1 , wherein the continuous polymeric phase comprises at least 70 weight %, based on the total polymer weight in the continuous polymeric phase, of one or more polymers derived from one or more of cellulose acetate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate. 
     
     
         6 . The method of  claim 1 , wherein the opacifying colorant is a carbon black that is present in an amount of at least 0.003 weight % and up to and including 0.2 weight %, based on the total weight of the chosen foamable aqueous composition. 
     
     
         7 . The method of  claim 1 , wherein the chosen foamable aqueous composition comprises at least 0.5 weight % and up to and including 10 weight % of the porous particles, based on the total weight of the chosen foamable aqueous composition, which porous particles have a mode particle size of at least 3 μm and up to and including 30 μm. 
     
     
         8 . The method of  claim 1 , wherein the surfactant of the one or more (c) additives is a foaming agent and the one or more (c) additives further comprise a foam stabilizing agent. 
     
     
         9 . The method of  claim 1 , wherein the one or more (c) additives further comprise an optical brightener in an amount of at least 0.01 weight % and up to and including 2 weight %, based on the total weight of the chosen foamable aqueous composition. 
     
     
         10 . The method of  claim 1 , wherein the one or more (c) additives comprise two or more materials selected from a foaming agent, a foam dispersing agent, a tinting colorant, an optical brightener, a flame retardant, an antimicrobial agent, and an inorganic filler. 
     
     
         11 . The method of  claim 1 , wherein the one or more (c) additives comprise an antimicrobial agent comprising silver metal, a silver-containing compound, copper metal, a copper-containing compound, or a mixture of any of these. 
     
     
         12 . A system for providing a foamed, opacifying element having a target light blocking value (LBV T ), comprising:
 (A) a set of foamable aqueous compositions, each of the foamable aqueous compositions independently having at least 35% solids and up to and including 70% solids, and independently comprising:
 (a) at least 0.05 weight % and up to and including 15 weight % of porous particles, each porous particle comprising a continuous polymeric phase and a first set of discrete pores dispersed within the continuous polymeric phase, the porous particles having a mode particle size of at least 2 and up to and including 50 μm and a porosity of at least 20 volume % and up to and including 70 volume %, and the continuous polymeric phase having a glass transition temperature greater than 80° C. and comprising a polymer having a viscosity of at least 80 centipoises and up to and including 500 centipoises at a shear rate of 100 see in ethyl acetate at a concentration of 20 weight % at 25° C., 
 (b) at least 20 weight % of a binder material; 
 (c) at least 0.0001 weight % of one or more additives comprising at least one surfactant; 
 (d) water; and 
 (e) at least 0.001 weight % of an opacifying colorant different from all of the one or more (c) additives, which opacifying colorant absorbs predetermined electromagnetic radiation, 
 all amounts being based on the total weight of the foamable aqueous composition, and wherein each of the foamable aqueous compositions can be foamed to provide a foamed aqueous composition having a foam density of at least 0.1 g/cm 3  and up to and including 0.5 g/cm 3 ; 
   (B) a set of mathematical formulae associated with the set of foamable aqueous compositions, wherein the set of mathematical formulae relate coating weight of the respective foamable aqueous compositions to respective light blocking values; and   (C) a data processor configured to perform a method for generating the foamed, opacifying element having the target light blocking value (LBV T ), the method comprising:
 choosing a target porous substrate having a first supporting side; 
 choosing a target light blocking value (LVB T ); 
 determining a light blocking value (LBV S ) of the target porous substrate; 
 calculating LBV T-S  as a difference between LBV T  and LBV S ; 
 choosing a foamable aqueous composition; 
 using a mathematical formula to obtain a dry coating weight for a single dry opacifying layer derived from the chosen foamable aqueous composition; and 
 using the dry coating weight to form the single dry opacifying layer as the only layer disposed on the first supporting side of the target porous substrate, such that the single dry opacifying layer has a light blocking value that is equal to LBV T-S , +10%. 
   
     
     
         13 . The system of  claim 12 , wherein choosing the target porous substrate and determining the mathematical formula for each of the foamable aqueous compositions are carried out using economic aspects or aesthetics aspects. 
     
     
         14 . The system of  claim 12 , wherein the continuous polymeric phase comprises one or more cellulose polymers. 
     
     
         15 . The system of  claim 12 , wherein the opacifying colorant is a carbon black that is present in an amount of at least 0.003 weight % and up to and including 0.2 weight %, based on the total weight of the chosen foamable aqueous composition. 
     
     
         16 . The system of  claim 12 , wherein the chosen foamable aqueous composition comprises at least 0.5 weight % and up to and including 10 weight % of the porous particles, based on the total weight of the chosen foamable aqueous composition, which porous particles have a mode particle size of at least 3 μm and up to and including 30 μm. 
     
     
         17 . The system of  claim 12 , wherein the one or more (c) additives further comprise metal flakes that are present within the porous particles. 
     
     
         18 . The system of  claim 12 , wherein the at least one surfactant of the one or more (c) additives is a foaming agent and the one or more (c) additives further comprise a foam stabilizing agent. 
     
     
         19 . The system of  claim 12 , wherein the one or more (c) additives further comprise an optical brightener in an amount of at least 0.01 weight % and up to and including 2 weight %, based on the total weight of the chosen foamable aqueous composition. 
     
     
         20 . The system of  claim 12 , wherein the one or more (c) additives comprise an antimicrobial agent comprising silver metal, a silver-containing compound, copper metal, a copper-containing compound, or a mixture of any of these.