Acrylate composite barrier coating process

• US 5,725,909 A
• Filed: 02/09/1996
• Issued: 03/10/1998
• Est. Priority Date: 10/04/1993
• Status: Expired due to Term

• Current Assignee: Presstek Incorporated (MAI Holdings, Inc.)
• Original Assignee: Catalina Coatings Incorporated
• Inventors: Langlois, Marc, Shaw, David G., Dawson, Eric, Cline, Daniel
• Primary Examiner(s): DUDASH, DIANA L
• Application Number:
  US08/599,596
• Time in Patent Office: 760 Days
• Field of Search: 427/316, 427/223, 427/419.5, 427/412.1, 427/404, 427/322, 427/419.2, 427/536, 427/296, 427/255.6, 427/255.7
• US Class Current: 427/412.1
• CPC Class Codes: B05D 1/60 Deposition of organic layers from vapour phase vapour phase deposition in general C23C14/00, C23C16/00
• CPC Class Codes: B05D 3/144 of polymeric substrates
• CPC Class Codes: B65D 1/0215 multilayered B65D81/3837 takes precedence
• CPC Class Codes: H01G 2/12 Protection against corrosion H01G2/10 takes precedence
• CPC Class Codes: H01G 4/20 using combinations of dielectrics from more than one of groups H01G4/02 - H01G4/06 H01G4/12 takes precedence
• CPC Class Codes: H01G 4/206 inorganic and synthetic material
• CPC Class Codes: H01G 4/32 Wound capacitors
• CPC Class Codes: Y10T 428/1334 Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• CPC Class Codes: Y10T 428/1338 Elemental metal containing
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1355 Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• CPC Class Codes: Y10T 428/1359 Three or more layers [continuous layer]
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31667 Next to addition polymer from unsaturated monomers, or aldehyde or ketone condensation product
• CPC Class Codes: Y10T 428/31699 Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31743 Next to addition polymer from unsaturated monomer[s]
• CPC Class Codes: Y10T 428/3175 Next to addition polymer from unsaturated monomer[s]
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31928 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31935 : Ester, halide or nitrile of addition polymer

Abstract

A thermoplastic container or packaging material is given low oxygen permeability by coating with a crosslinked acrylate layer and a layer of oxygen barrier material deposited over the acrylate layer. Another acrylate layer may be deposited over the oxygen barrier. The oxygen barrier is selected from the group consisting of silicon oxide, aluminum oxide and metal. The acrylate layer may be formed from a photopolymerizable polyfunctional acrylate that is sufficiently low viscosity to be sprayed on the substrate or applied by dipping. Alternatively, the acrylate layer is a polymerization product of an acrylate monomer which is evaporated in a vacuum, condensed on the substrate and polymerized by irradiation by ultraviolet or an electron beam. The surface of the thermoplastic substrate is prepared for deposition of the acrylate by either flame treating the surface of the substrate to heat it above its melting point without deforming the substrate to thereby smooth the surface, or by plasma treating the surface for enhancing adhesion of the acrylate. Chilling the substrate enhances deposition efficiency.

Claims

1. A method for forming an adherent barrier layer on a thermoplastic substrate comprising the steps of:

heating the surface of the substrate above its melting point and cooling the surface of the substrate below its melting point;

evaporating acrylate monomer having a molecular weight in the range of from 150 to 600;

depositing the evaporated acrylate on the cooled surface of the substrate;

polymerizing the acrylate for forming a cross-linked acrylate layer; and

depositing a layer of oxygen barrier material over the cross-linked acrylate layer.

2. A method as recited in claim 1 wherein the heating step comprises exposing the substrate to a flame for a sufficient time to melt the surface of the thermoplastic material without deforming the substrate.

3. A method as recited in claim 1 wherein the step of depositing a layer of an oxygen barrier material comprises depositing a material selected from the group consisting of silicon oxide, aluminum oxide and metal to the substrate.

4. A method as recited in claim 1 wherein the step of depositing a layer of an oxygen barrier material comprises depositing a material selected from the group consisting of silicon oxide and aluminum oxide.

5. A method for forming an adherent barrier layer on a thermoplastic substrate comprising the steps of:

heating the surface of the substrate above its melting point and cooling the surface of the substrate below its melting point;

evaporating a blend comprising at least one acrylate monomer having a molecular weight in the range of from 150 to 400 and a second acrylate having a molecular weight more than 600;

depositing the evaporated acrylate on the cooled surface of the substrate;

polymerizing the acrylate for forming a cross-linked acrylate layer; and

depositing an oxygen barrier material over the cross-linked acrylate layer.

6. A method for forming an adherent barrier layer on a thermoplastic substrate comprising the steps of:

evaporating at least one polyfunctional acrylate;

condensing the acrylate on the surface of the substrate;

polymerizing the acrylate for forming a cross-linked acrylate layer; and

plasma treating the cross-linked acrylate surface immediately before depositing an oxygen barrier material over the cross-linked acrylate layer.

7. A method for forming an adherent barrier layer on a thermoplastic substrate comprising the steps of:

heating the surface of the substrate above its melting point and cooling the surface of the substrate below its melting point;

chilling the substrate to a temperature below ambient temperature;

placing the chilled substrate in a vacuum chamber;

condensing at least one liquid polyfunctional acrylate monomer on the substrate while the substrate is still at a temperature below ambient temperature;

polymerizing the acrylate for forming a cross-linked acrylate layer; and

depositing an oxygen barrier material over the cross-linked acrylate layer.

8. A method for forming an adherent barrier layer on a thermoplastic substrate comprising the steps of:

heating the surface of the substrate above its melting, point and cooling the heated surface of the substrate below its melting point;

preheating a polyfunctional acrylate prepolymer to a temperature above ambient temperature and lower than a temperature where the acrylate polymerizes;

atomizing the preheated acrylate prepolymer into a heated vaporization chamber in a vacuum system;

vaporizing the acrylate prepolymer in the vaporization chamber and discharging the vaporized prepolymer into the vacuum system;

depositing the prepolymer on the substrate;

polymerizing the acrylate prepolymer for forming a cross-linked acrylate layer; and

depositing an oxygen barrier material over the cross-linked acrylate layer.

9. A method for making a container with low oxygen permeability comprising the steps of:

flame treating the outside surface of a thermoplastic container;

depositing a polyfunctional acrylate on the flame treated surface of the container;

polymerizing the acrylate to form a cross-linked acrylate layer;

depositing a layer of oxygen barrier material selected from the group of silicon oxide, aluminum oxide and metal on the outside surface of the container;

depositing a polyfunctional acrylate on the layer of oxygen barrier material; and

polymerizing the acrylate to form a cross-linked acrylate layer over the oxygen barrier material.

10. A method as recited in claim 9 wherein at least one step of depositing an acrylate comprises depositing a blend comprising at least one acrylate monomer having a molecular weight in the range of from 150 to 400 and a second acrylate having a molecular weight more than 600.

11. A method as recited in claim 9 further comprising the steps of:

chilling the container to a temperature below ambient temperature; and

placing the chilled container in a vacuum chamber; and

wherein the depositing step comprises condensing the acrylate monomer on the container while the container is still at a temperature below ambient temperature.

12. A method for forming an adherent barrier layer on a thermoplastic sheet substrate comprising the steps of:

depositing a metal layer on a thermoplastic sheet substrate;

vapor depositing a polyfunctional acrylate on the metal layer before the exposed surface of the metal layer contacts any solid surface; and

polymerizing the acrylate for forming a cross-linked acrylate layer before the exposed surface of the acrylate layer contacts any solid surface.

13. A method for forming an acrylate polymer layer comprising the steps of:

preheating a polyfunctional acrylate prepolymer to a temperature above ambient temperature and lower than a temperature where the prepolymer polymerizes;

atomizing the preheated prepolymer into a heated vaporization chamber in a vacuum system;

vaporizing the prepolymer in the vaporization chamber and discharging the vaporized prepolymer into the vacuum system;

depositing the prepolymer on a substrate; and

polymerizing the acrylate prepolymer for forming a crosslinked acrylate layer.

14. A method as recited in claim 13 comprising preheating the prepolymer to a temperature of up to 100°

C.

15. A method as recited in claim 13 comprising preheating the prepolymer to a temperature of about 100°

C.