Stable solid particulate system for controlling humidity to a selected range

A solid particulate system for controlling humidity to a selected range comprising:

• a hydrophobic silica component;
• wherein the hydrophobic silica component comprises about 4 to 10 wt.% hydrophobic nano silica particles and from about 96 to 90 wt.% of a mixture of a saturated solution of at least one soluble solid and undissolved at least one soluble solid;
• and
• a hydrophilic silica component;
• wherein the hydrophilic silica component comprises from about 20 to 40 wt.% hydrophilic silica particles and about 80 to 60 wt.% of the mixture of the saturated solution of at least one soluble solid and undissolved at least one soluble solid;
• wherein the mixture of saturated solution of at least one soluble solid and undissolved at least one soluble solid comprises a saturated solution of at least one soluble solid dissolved in a polar solvent and a small excess of undissolved at least one soluble solid in the saturated solution;
• wherein the small excess of soluble solid is from about 0.1 to 10 wt. % excess of the at least one soluble solid dissolved into a polar liquid;
• wherein the amount of at least one soluble solid is present in the particulate in the amount of from about 20 to 90 wt. %;
• wherein the at least one soluble solid provides an equilibrium relative humidity when in a saturated solution in the polar liquid;
• wherein system is made by blending together from about 4 to 40 wt.% of the hydrophilic component with about 96 to 60 wt.% of the hydrophobic component;
• wherein the particulate system is stable and externally dry;
• and
• wherein the particulate system absorbs and releases moisture.

A relative humidity control system comprising:

• an enclosed system comprising a container;
• and
• a solid particulate system for controlling humidity to a selected range within the container comprising:
• a hydrophobic silica component;
• wherein the hydrophobic silica component comprises about 4 to 10 wt.% hydrophobic nano silica particles and from about 96 to 90 wt.% of a mixture of a saturated solution of at least one soluble solid and undissolved at least one soluble solid;
• and
• a hydrophilic silica component;
• wherein the hydrophilic silica component comprises from about 20 to 40 wt.% hydrophilic silica particles and about 80 to 60 wt.% of the mixture of saturated solution of at least one soluble solid and undissolved at least one soluble solid;
• wherein the mixture of saturated solution of at least one soluble solid and undissolved at least one soluble solid comprises a mixture of a saturated solution of at least one soluble solid dissolved in a polar solvent and a small excess of undissolved at least one soluble solid in the saturated solution;
• wherein the at least one soluble solid provides an equilibrium relative humidity when in a saturated solution with the polar liquid;
• wherein system is made by blending together from about 4 to 40 wt.% of the hydrophilic component with about 96 to 60 wt.% of the hydrophobic component;
• wherein the particulate system is stable and externally dry;
• and
• wherein the particulate system absorbs and releases moisture to control the relative humidity.