CN1352798A - Conductive or Static Dissipative Coatings - Google Patents

Abstract

Conductive or static dissipative coatings, films or laminates suitable for packaging sensitive electronic components are disclosed. The conductivity or static dissipative properties are achieved by adding an effective amount of a quaternary ammonium compound to the base resin.

Description

Conductive or Static Dissipative Coatings

Background of the Invention

1. Field of invention

The present invention relates to a film, in particular a self-sustaining film or a thin layer in a laminate or a coating of such a laminate, which is electrically conductive and/or has electrostatic dissipative properties. These materials are especially useful for packaging electronic components that may be affected or destroyed by electrostatic buildup of electronic components during shipping, handling or storage.

2. Background of the invention

Resin materials, such as polymeric materials, are known to be useful in forming coatings, self-sustaining films, thin layers in laminated structures and coatings thereon.

However, polymeric materials are generally not conductive, and in fact these materials are widely used as insulators due to their non-conductive properties.

Previous attempts to impart conductive properties to polymers have involved the addition of conductive materials, in particular such as carbon or similar materials such as graphite, as fillers for the polymeric material. Materials containing eg carbon are only effective if the conductive material is present in an amount (by weight or volume) and uniformly dispersed in the polymeric material so as to form a continuous path for the transmission of electrical energy. The problem of containing such a large amount of material and uniformly dispersing a material such as carbon greatly affects the conductive properties of the resulting composite material. The use of carbon also renders any polymeric material added in conductivity to be predominantly black due to its nature, ie its inherent colour.

Therefore, there is a need in the packaging industry for materials that are more aesthetically pleasing than black plastic films.

Brief description of the invention

To impart electrical conductivity and static dissipative properties to polymeric materials, to impart electrical conductivity or electrostatic dissipative properties to films or coatings consisting essentially of polymeric materials, it is especially useful in the form of self-sustaining films, as thin layers in laminated structures or as Coatings on paper or in laminated structures to package electronic components and/or conductive materials that are susceptible to damage from static buildup during storage, transport and handling. These polymeric materials with conductive or static dissipative properties are useful as packaging materials, especially for packaging electronic components.

Detailed description of the preferred implementation

Polymeric materials, such as acrylic-based polymers, especially methyl methacrylate-containing polymers, form coatings and films well due to their physical properties, especially their optical clarity. These properties make these materials ideal for use as processed packaging materials. However, these polymeric materials do not conduct electricity or transport electrical energy, and are generally considered "insulators," meaning they do not conduct electrical current.

The present invention discloses a novel formulation for rendering a polymeric material electrically conductive or Electrostatic dissipative performance, so that it has static dissipative performance lower than 10 ¹² Ω/sq and electrical conductivity lower than 10 ⁵ Ω/sq. Materials suitable for mixing with the polymeric material are quaternary ammonium compounds. These quaternary ammonium compounds in an alcoholic solvent/carrier, preferably an isopropanol/ethanol mixture, form a liquid mass which is readily mixed with the polymeric material. The liquid containing the quaternary ammonium preferably contains about 41% by weight alcohol, most preferably 40% isopropanol and 1% ethanol. Quaternary ammonium salts are known to be used as softening agents, especially in laundry formulations, or applied to paper or foam during drying of washed clothes. However, the use of these substances as components of films, laminates or coatings was not known prior to the present invention. A suitable material is available from ACL Inc., 1960 E. Devon Avenue, Elkgrove Village, Illinois 60007 under the designation "STATICIDE 3000G". This material is commercially available as a liquid concentrate that appears as a clear yellow substance with a pleasant odor and evaporates faster than water. The commercially available "STATICIDE 3000G" has a specific gravity of 0.97, a density (g/ml) of 0.97, a vapor pressure (mm) at 20°C of 36, and a vapor density of 2.1. The volatile percentage (by volume) is about 40%, and the pH is 7.1±1.

After mixing the quaternary ammonium-containing liquid with the polymeric material, the resulting composition can then be formed into a self-sustaining film or used as a thin layer in a laminated structure or as a coating for paper or laminated structures. When used in laminated structures, the electrically conductive or static dissipative materials of the present invention should preferably be used as the outer layer, ie on one or both sides of the film. Between the two outer layers of the film, other thin layers may include metallized or non-metallized surfaces and one or more layers of plastic film, fabric, nonwoven material or paper, each coated with a coating or uncoated. The mixture of the quaternary ammonium-containing liquid and other components can be formed into a film, applied as a coating or formed into a layer by conventional techniques known in the art for preparing other polymeric films, coatings and/or films.

Typical requirements for a self-sustaining film are a thickness of about 0.5 to about 500 mils, a tensile strength (measured by ASTM D-882) of 0 to 100 psi, and a puncture resistance (measured by FTMS 101C method 2065) of 0-150 lbs, turbidity (by ASTM D-1003 test method) is clear to opaque; optical density (by McBeth test method) is 0-4.0%, light transmission (by ASTM D-1003 test method) 0-100%. The seam strength of the film from which the package is made shall be breakable when determined by the ASTM D-882 test method.

The best mode of implementing the present invention is described by the following examples: Example 1 (all parts are by weight)

                                   

27.0 H ₂ O

2.6 NH ₄ OH 28°

336.0 Joncryl 82 ^*

74.0 Joncryl 61 ^**

29.8 Jonwax 28 ^***

15.0 Zinc oxide solution ^***

120.0 H ₂ O

3.0-60.0 Staticide 3000G

^* Aqueous solution of methyl methacrylate sold by SCJohnson & Sons, Inc., US Specialty Chemicals, 1525 Howe Street, Racine, Wisconsin

^** Methyl methacrylate in water, sold by SCJohnson & Sons, Inc., US Specialty Chemicals, 1525 Howe Street, Racine, Wisconsin

^*** Polyethylene wax emulsion containing about 35% solids, sold by SC Johnson & Sons, Inc., US Specialty Chemicals, 1525 Howe Street, Racine. Wisconsin

^**** is actually a dispersion of zinc oxide particles in water carrier Example 2

                                     

400.0 Spectra-Guard 763 ^*****

110.0 H ₂ O

4.0-20.0 3000-G Staticide Concentrate

^***** A film-forming material commercially available from Spectra-Kote Corporation, Fourth Street and East Water Street, Gettysburg, Pennsylvania, and described in US 5,393,566 and 5,531,863, the entire contents of which are incorporated herein by reference. Example 3

                                 

400.0 Spectra-Guard 763

110.0 H ₂ O

4.0-20.0 3000-G Staticide Concentrate

5.0-25.0 Joncryl 89 ^******

^***** Sold by SC Johnson & Sons, Inc., US Specialty Chemicals, 1525 Howe Street, Racine, Wisconsin.

The preceding examples demonstrate that levels of conductive material ranging from about 1 to about 10% by weight are sufficient to form coatings, self-sustaining films, and/or thin layers in laminated structures having the aforementioned surface resistance.

Chemical properties including contact corrosion by FTMS 101C Method 3005 show no visible signs after deterioration determination; ion content (Na ⁺ , F ^- , PO ₄ ^3- and SO ₄ ^2- ions) below measurable levels, Free of amines and amides.

It will be clear to those skilled in the art that the present inventors have provided a formulation which imparts electrostatic dissipative properties and/or electrical conductivity to coatings, films or laminates based primarily on polymeric materials, making the article a Aesthetic packaging material, especially for electronic components that may be damaged by static electricity during storage, transport and/or handling. However, it is obvious that other formulations and uses thereof can be adopted by those skilled in the art without departing from the spirit and scope of the present invention.

Amendments pursuant to Article 19 of the Treaty

CLAIMS 1. A self-sustaining film comprising a composition containing an acrylic resin, said composition containing 1-10% by weight of a quaternary ammonium compound based on the weight of the composition, so that the self-sustaining film has static dissipative properties and electrical conductivity.

2. The self-sustaining film of claim 1, wherein the acrylic resin is a methyl methacrylate-containing polymer.

3. The self-sustaining film according to claim 1, further comprising a zinc oxide particle dispersion.

4. The self-sustaining film of claim 1 further comprising a polyethylene wax emulsion.

5. A paper layer coated with a conductive polymer composition containing an acrylic resin, said polymer composition containing 1-10% by weight of a quaternary ammonium compound by weight of the composition, so that the paper layer has Static Dissipative and Conductive.

6. The paper layer of claim 5, wherein the acrylic resin is a methyl methacrylate-containing polymer.

7. The paper layer of claim 5, further comprising a dispersion of zinc oxide particles.

8. The paper layer of claim 5, further comprising a polyethylene wax emulsion.

9. A laminate comprising two or more thin layers coated on at least one surface of the thin layers with a conductive polymer composition comprising an acrylic resin, said polymer composition comprising a combination of 1-10% by weight of the quaternary ammonium compound based on the weight of the material, so that the laminate has static dissipative properties and electrical conductivity.

10. A packaging material comprising a conductive polymer composition layer containing an acrylic resin, said polymer composition containing 1-10% by weight of a quaternary ammonium compound by weight of the composition, so that the polymer The composition is static dissipative and conductive, and at least one material selected from the group consisting of paper, fabric, nonwoven material, and combinations thereof.

11. The packaging material of claim 10, wherein said at least one material includes a metalized surface.

12. The packaging material of claim 10, wherein said at least one material is paper.

13. The packaging material of claim 12, further comprising a dispersion of zinc oxide particles.

14. The packaging material of claim 12, further comprising a polyethylene wax emulsion.

Claims (14)

CLAIMS 1. An electrically conductive polymeric composition comprising an acrylic resin comprising from about 1 to about 10% by weight of the composition of a quaternary ammonium compound, said polymeric composition being electrostatically dissipative and electrically conductive. 2. The conductive coating composition of claim 1, wherein the acrylic resin is a methyl methacrylate-containing polymer. 3. The conductive coating according to claim 1, further comprising a zinc oxide particle dispersion. 4. The conductive coating of claim 3, further comprising a polyethylene wax emulsion. 5. A coating formed from the conductive polymeric component of claim 1. 6. A self-sustaining film formed from the conductive polymeric composition of claim 1. 7. A paper layer coated with the conductive polymeric composition of claim 1. 8. A laminate comprising two or more thin layers coated on at least one surface of the thin layers with the conductive polymeric composition of claim 1. 9. A packaging material comprising the conductive polymeric composition of claim 1 and at least one material selected from the group consisting of paper, fabric, non-woven material, plastic film, and combinations thereof. 10. The packaging material of claim 9, wherein said at least one material includes a metalized surface. 11. A method of converting an electrically insulating polymeric material into a conductive material without the use of carbon, graphite or metallic components, said method comprising adding to the polymeric material a conductively effective amount of a quaternary ammonium compound. 12. The method of claim 11, wherein said adding step includes the step of adding said quaternary ammonium compound to the polymeric material in an alcoholic solution. 13. The method of claim 12, wherein the alcoholic solution comprises a mixture of isopropanol and ethanol. 14. The method of claim 11, wherein the amount of the quaternary ammonium compound is from about 1 to about 10% by weight.