Process for hydrosonically microaperturing

A method for forming microapertures in a film having a thickness of about 10 mils or less wherein the area of each of the formed microapertures is generally greater than about 10 square micrometers, the method comprising the steps of:

• (a) placing the film on a pattern anvil having a pattern of raised areas wherein the height of the raised areas is greater than the thickness of the film;
• (b) conveying the film, while placed on the pattern anvil, through an area where a liquid is applied to the film;
• and
• (c) subjecting the film to a sufficient amount of ultrasonic vibrations in the area where the liquid is applied to the film to microaperture the film;
• and
• whereby the film is microapertured in a pattern generally the same as the pattern of raised areas on the pattern anvil.

A method for forming microapertures in a thin sheet material having a thickness of about 10 mils or less wherein the area of each of the formed microapertures is generally greater than about 10 square micrometers, the method comprising the steps of:

• (a) placing the thin sheet material on a pattern anvil having a pattern of raised areas wherein the height of the raised areas is greater than the thickness of the thin sheet material;
• (b) conveying the thin sheet material, while placed on the pattern anvil, through an area where a liquid selected from the group consisting of one or more of water, mineral oil, a chlorinated hydrocarbon, ethylene glycol and a solution of 50 volume percent water and 50 volume percent 1 propanol is applied to the thin sheet material and
• (c) subjecting the thin sheet material to a sufficient amount of ultrasonic vibrations in the area where the liquid is applied to the thin sheet material to microaperture the thin sheet material;
• and
• whereby the thin sheet material is microapertured in a pattern generally the same as the pattern of raised areas on the pattern anvil.

A method for forming microapertures in a thin sheet material having a thickness of about 10 mils or less wherein the area of each of the formed microapertures is generally greater than about 10 square micrometers, the method comprising the steps of:

• (a) placing the thin sheet material on a pattern anvil having a pattern of raised areas wherein the height of the raised areas is greater than the thickness of the thin sheet material;
• (b) conveying the thin sheet material, while placed on the pattern anvil, through an area where a liquid chlorinated hydrocarbon selected from the group consisting of 1, 1, 1 trichloroethane and carbon tetrachloride is applied to the thin sheet material;
• and
• (c) subjecting the thin sheet material to a sufficient amount of ultrasonic vibrations in the area where the liquid is applied to the thin sheet material to microaperture the thin sheet material;
• and
• whereby the thin sheet material is microapertured in a pattern generally the same as the pattern of raised areas on the pattern anvil.

A method for forming microapertures in a thin sheet material having a thickness of about 0.5 mil to about 5 mils wherein the area of each of the formed microapertures is generally greater than about 10 square micrometers, the method comprising the steps of:

• placing the thin sheet material on a pattern anvil comprising:
• a heavy duty wire mesh screen;
• a shim plate;
• and
• a fine mesh wire mesh screen a having a pattern of
• raised knuckles wherein the height of the raised
• knuckles is greater than the thickness of the thin
• sheet material;
• conveying the thin sheet material, while placed on the fine mesh wire mesh screen, through an area where water is applied to the thin sheet material;
• and
• utilizing an ultrasonic horn to subject the thin sheet material to a sufficient amount of ultrasonic vibrations in the area where the water is applied to the thin sheet material to microaperture the thin sheet material ;
• and
• whereby the thin sheet material is microapertured with a microaperture density of at least about 100,000 microapertures per square inch in a pattern generally the same as the pattern of raised knuckles on the fine mesh wire mesh screen.

A method for forming microapertures in a thin sheet material having a thickness of about 0.25 mil to about 1 mil wherein the area of each of the formed microapertures ranges from about 10 square micrometers to about 100 square micrometers, the method comprising the steps of:

• placing the thin sheet material on a pattern anvil comprising:
• a heavy duty wire mesh screen;
• a shim plate;
• and
• a fine mesh wire mesh screen having a pattern of raised knuckles wherein the height of the raised knuckles is greater than the thickness of the thin sheet material;
• conveying the thin sheet material, while placed on the fine mesh wire mesh screen, through an area where water is applied to the thin sheet material;
• and
• utilizing an ultrasonic horn to subject the thin sheet material to a sufficient amount of ultrasonic vibrations in the area where the water is applied to the thin sheet material to microaperture the thin sheet material;
• and
• wherein the thin sheet material is microapertured with a microaperture density of at least about 100,000 microapertures per square inch in a pattern generally the same as the pattern of raised knuckles on the fine mesh wire mesh screen.