Electrostatic method for forming structures and articles

• US 3,930,061 A
• Filed: 04/08/1974
• Issued: 12/30/1975
• Est. Priority Date: 04/08/1974
• Status: Expired due to Term

• Current Assignee: James A. Scharfenberger
• Original Assignee: James A. Scharfenberger
• Inventors: Scharfenberger, James A.
• Primary Examiner(s): Newsome, J. H.
• Application Number:
  US05/459,059
• Time in Patent Office: 631 Days
• Field of Search: 117/93.4,93.41,93.42,93.43,93.44,105.5 239/3,15 264/24,257,DIG.53,309 118/315,316,621,627,629 427/27,33,426,196
• US Class Current: 427/483
• CPC Class Codes: B29C 41/006 using an electrostatic field for applying the material
• CPC Class Codes: B29C 41/365 Construction of spray-up equipment, e.g. spray-up guns spraying apparatus in general B05B

Abstract

An electrostatic method for forming structures from plural component materials includes the formation of a liquid resin into spray particles at one location, the formation of a liquid curing agent into spray particles at another location, and the establishment of an electrostatic field adjacent these locations to enhance mixing of the resin and curing agent particles and deposition of the mixture on a substrate to solidify and form a structure. The electrical conductivity of the liquid resin and liquid curing agent can be adjusted to enhance the mixing and electrostatic deposition and to provide a method of employing an electrically nonconductive substrate on which the structure can be formed.

Claims

1. A METHOD OF FORMING A STRUCTURE FROM PLURAL COMPONENT MATERIAL WITH ELECTROSTATIC DEPOSITION COMPRISING FORMING A PROMOTED RESINOUS MATERIAL INTO A SPRAY AT ONE SITE;

ESTABLISHING AN ELECTRISTATIC FIELD FROM A CHARGING ELECTRODE ADJACENT THE SITE OF FORMATION OF THE SPRAY OF RESINOUS MATERIAL OT CHARGE THE SPRAY WITH ONE POLARITY;

SIMULTANEOUSLY FORMING A CATLAYST MATERIAL FOR SAID RESINOUS MATERIAL TO CHARGE THE SPRAY WITH ONE POLARITY;

CENT THE CHARGING ELECTRODE, AND CHARGING SAID CATALYST SPRAY TO THE OPPOSITE POLARITY FROM SAID PROMOTED RESIN, THE SITE OF FORMATION OF THE SPRAY OF CATALYST MATERIAL ACTING AS A TERMINOUS OF THE ELECTROSTATIC FIELD FROM SAID CHARGING ELECTRODE;

AND PROJECTING THE SPRAYS FROM SAID SITES OF FORMATION SO THAT THEY CONVERGE AND MIX, THE VOLUME OF SAID SPRAYED RESIN BEING GREATER THAN THAT OF SAID CATALYST MATERIAL WHEREBY SAID SPRAY OF MIXED PROMOTED RESIN AND CATALYST RETAINS A NET CHARGE OF SAID ONE POLARITY, AND ARE DIRECTED FOR ELECTROSTATIC DEPOSITION ON A SURFACE MAINTAINED AT A SPRAY ATTRACTING POTENTIAL ON WHICH THE STRUCTURE IS TO BE FORMED.

2. The method of claim 1 wherein said electrostatic field adjacent the charging electrode creates a highly ionized zone of ions, and said grounded site of formation of catalyst material attracts ions from said highly ionized zone so that they collide with the spray of promoted resinous material, said ions being substantially entirely carried away by the spray of promoted resinous material.

3. The method of claim 1 including the step of forming promoted resinous material into a second spray at a second site more remote from the site of formation of the first spray than from the grounded site of formation of catalyst material and establishing an electrostatic field from a charging electrode adjacent said second site to charge the second spray of resinous material.

4. The method of claim 3 wherein said site of formation of said first spray of resinous material and said second site of formation of said second spray of resinous material have between them said grounded site of formation of catalyst material into a spray.

5. A method of forming a structure of plural component material comprising forming a spray of an amount of resin and electrostatically charging the spray to one electrical polarity adjacent one terminus of an electrostatic field;

forming a spray of an amount of catalyst material for said resin and electrostatically charging said catalyst material to the other polarity adjacent an opposite terminus of the electrostatic field;

said amount of catalyst being less than said amount of resin;

projecting the charged spray of resin material and the charged spray of catalyst material so said sprays converge and mix, retaining a net charge, and are deposited electrostatically at the site of formation of the structure;

the mixed catalyst and resin curing to form said plural component structure.

6. The method of claim 5 including the step of cutting a fibrous insulating material into lengths on the order of one inch or less, triboelectrically charging said cut fibers and projecting said charged, cut fibers into the sprays of resin and catalyst material.

7. The method of claim 5 wherein the spray of resin contains at least twenty times as much material as the spray of catalyst.

8. The method of claim 7 wherein the resin is cobalt naphthenate promoted polyester resin and the catalyst is methyl ethyl ketone peroxide.

9. A method of electrostatically depositing plural component material on a mold of electrically nonconductive material comprising adjusting the electrical conductivity of a resin material to less than 100 megohm-centimeters;

forming a spray of an amount of conductive resin and electrostatically charging the spray;

forming a spray of an amount of catalyst;

said amount of catalyst being less than said amount of resin;

projecting the charged spray of resin material and the spray of catalyst material so said sprays converge and mix to form a charged composite spray composed of conductive resin and catalyst material;

providing the mold with a ground connection; and

directing the charged composite spray of conductive resin and catalyst at said ground connection on said mold to form a conductive liquid layer of resin and catalyst and proceeding to direct said charged composite spray at the edge of said layer until the entire mold is coated.

10. A method of forming a structure from liquid material including a liquid resin and a curing agent for said resin, which, when mixed with the said resin, converts the mixture from liquid to solid phase comprising adjusting the electrical conductivity of the curing agent to an electrical resistivity of less than 100 megohm-centimeters;

delivering the liquid resin to a first site of atomization and atomizing the liquid resin to form a spray;

delivering the conductive curing agent to a second site of atomization and forming the electrically conductive liquid curing agent at said second site of atomization into a thin stream and atomizing the liquid curing agent to form a spray;

creating an electrostatic field from a site adjacent the first site of atomization of resin and maintaining the thin stream of conducting catalyst as a terminus of lines of force of the electrostatic field to charge a spray of resin material to one polarity and to form the particles at the second site of atomization with a charge of a polarity by which they are attracted to a spray of resin material and directing the spray of resin and the spray of curing agent so that the sprays mix and are deposited on a mold surface and cure thereon to form said structure.

11. The method of claim 10 wherein said resin material is atomized at a rate of at least twenty times the rate of atomization of the curing agent material.

12. The method of claim 10 wherein the electrostatic field creates a highly ionized zone of ions, and said ions acting in response to the electrostatic field, are attracted toward the thin stream of conductive liquid curing agent and traverse the spray of resin material.

13. The method as set forth in claim 10 wherein the electrical conductivity of the resin material is adjusted to an electrical resistivity of less than 100 megohm-centimeters and the sprays are directed to an electrically nonconductive mold surface which has a conductive portion maintained at ground potential, the sprays being directed to apply a liquid film at the grounded conductive portion first and then directed in such a manner that the entire mold is coated while maintaining a liquid film between the grounded conductive portion of the mold surface and the point of application of the plural component material.