Minnesota Mining and Manufacturing Company

3m Innovative Properties Company

Other

Albert E Seaver

William Keith Leonard

Albert I Everaerts

William M Lamanna

George V Tiers

David W Leonard

Daniel R Danielson

Mieczyslaw H Mazurek

Ross M Kedl

William R Berggren

Carey J Eckhardt

Eugene E Harkins

Luther E Erickson

Lyle N Scheel

The uniformity of a wet coating on a substrate is improved by contacting the coating at a first position with the wetted surfaces of periodic pick-and-place devices, and re-contacting the coating with such wetted surfaces at positions on the substrate that are different from the first position and not periodically related to one another with respect to their distance from the first position. A coating is applied to a substrate by applying an uneven wet coating, contacting the coating at a first position with the wetted surfaces of periodic pick-and-place devices, and re-contacting the coating with such wetted surfaces at positions on the substrate that are different from the first position and not periodically related to one another with respect to their distance from the first position. These methods can provide extremely uniform coatings and extremely thin coatings, at very high rates of speed. The coatings can be applied in lanes with sharply defined edges and independently adjustable coating calipers. The pick-and-place devices facilitate drying and reduce the sensitivity of drying ovens to coating caliper surges. Equipment to carry out these methods is simple to construct, set up and operate, and can easily be adjusted to alter coating thickness and compensate for coating variation.

Wet coating improvement station

A liquid coating is formed on a substrate by electrostatically spraying drops of the liquid onto a liquid-wetted conductive transfer surface and transferring a portion of the thus-applied liquid from the transfer surface to the substrate. Optionally, one or more nip rolls force the substrate against the transfer surface, thereby decreasing the time required for the drops to spread and coalesce into the coating. Preferably, the coating is passed through an improvement station comprising two or more pick-and-place devices that improve the uniformity of the coating. The coating can be transferred from the conductive transfer surface to a second transfer surface and thence to the substrate. Insulative substrates such as plastic films can be coated without requiring substrate pre-charging or post-coating neutralization. Porous substrates such as woven and nonwoven webs can be coated without substantial penetration of the coating into or through the substrate pores.

Electrostatic spray coating apparatus and method

Method for improving the uniformity of a wet coating on a substrate using pick-and-place devices

A liquid coating is formed by spraying drops of liquid onto a substrate or a transfer surface from an electrostatic spray head that produces a mist of drops and a wet coating in response to an electrostatic field. During spraying, the electrostatic field is repeatedly altered to change the pattern deposited by the drops. The wet coating can be contacted with two or more pick-and-place devices that improve the uniformity of the coating.

Variable electrostatic spray coating apparatus and method

Compositions containing conductivity enhancers, which are capable of being coated onto a substrate by means of electrostatic assistance. The compositions comprise one or more cationically polymerizable monomer(s), one or more cationic initiator(s), and one or more non-volatile conductivity enhancer(s) having anionic and cationic portions which are soluble in the monomer(s) and which do not interfere with cationic polymerization wherein the anionic portion is a non-coordinating carbon-containing anion. The compositions may further comprise one or more dissociation enhancing agent(s), oligomer(s) or polymer(s), preferably co-reactive, free-radically curable monomer(s), free-radical generating initiator(s), leveling agents, and other additives or adjuvants to impart specific properties to the polymerized composition.

Cationically polymerizable compositions capable of being coated by

Free-radically polymerizable release coating compositions containing conductivity enhancers, which are capable of being electrosprayed onto a substrate. The compositions comprise (a) about 100 parts by weight of one or more free-radically polymerizable vinyl monomer(s), (b) from about 0.05 to about 250 parts by weight of one or more polydiorganosiloxane polymer(s) copolymerizable with the vinyl monomer(s), and (c) from about 0.10 to about 10 parts by weight, based on 100 parts by weight of (a) and (b), of one or more non-volatile conductivity enhancer(s), which are soluble in the monomer(s) and which do not interfere with polymerization, wherein the composition may be electrosprayed. The composition may further comprise from about 0.1 to about 5 parts by weight of one or more initiator(s) based on 100 parts by weight of monomer(s) and polydiorganosiloxane polymer(s). Another embodiment of the present invention further comprises at least 0.1 part by weight, based on 100 parts by weight of monomer(s) and polydiorganosiloxane polymer(s), of one or more dissociation enhancing agent(s) soluble in the monomer(s).

Electrosprayable release coating

Compositions containing conductivity enhancers, which are capable of being coated onto a substrate by means of electrostatic assistance. The compositions comprise one or more free-radically curable monomer(s), and one or more non-volatile conductivity enhancer(s), having cationic and anionic portions, which are soluble in the monomer(s) and which do not interfere with free-radical polymerization, wherein said anionic portion is a non-coordinating organophilic carbon-containing anion. The compositions may further comprise one or more initiator(s), one or more dissociation enhancing agent(s), cross-linking agent(s), cationically polymerizable monomer(s), cationic initiator(s), leveling agents, oligomer(s) or polymer(s), preferably co-reactive, and other additives or adjuvants to impart specific properties to the cured coating.

Free-radically polymerizable compositions capable of being coated by

A coating device has a first half and a second half located adjacent the first half to form a slot between the first and second halves. A porous material, having a thickness greater than the height of the slot, is disposed in the slot to compress uniformly along its width. The porous material has a porosity and a height selected in combination with each other to create a predetermined pressure drop through the slot and to maintain the pressure drop to create the desired flow rate along the slot width. The size of the pores in the porous material can be less than 25 .mu.m and the exit pressure drop through the slot can be at least one thousand times greater than could be obtained without the porous material.

Restricted flow die

An electrospray coating head system for applying thin coating to a substrate comprising a slot or blade to meter a liquid onto a shaping structure which forces the liquid to have a single continuous and substantially constant radius of curvature around the shaping structure. A voltage applied to the liquid around the shaping structure causes the liquid to produce a series of filaments which are spatially and temporally fixed, the number of filaments being defined by a simple adjustment in the applied voltage. The filaments break up into a uniform mist of charge droplets and are driven to a substrate by electric fields to produce a coating. Also a method for electrospray coating wherein liquid to be coated is dispensed from a metering portion to a lower shaping means where it achieves a single continuous and substantially constant radius of curvature, a voltage is applied to produce a series of filaments of the liquid which are spatially and temporally fixed, and the filaments break up into a uniform mist of charge droplets.

Electrospray coating apparatus and process utilizing precise control of

An electrostatic coating system for applying very thin coating to a substrate in air at atmospheric pressure comprises a plurality of spaced capillary needles positioned in at least two rows and fed with coating liquid via a manifold. The needles are disposed concentric within holes in an extractor plate, a potential is developed between the capillary needles and the extractor plate affording a reduction of the liquid to a mist of highly charged droplets drawn to the substrate by a second electrical field. Insulative layers on the extractor plate provide increased droplet control.

Growing community of inventors

Woodbury, MN, United States of America

Albert E Seaver