Multilayer film having at least one thin layer and continuous process for forming such a film

Patent metadata

Field	Value
Publication number	US-9914854-B2
Application number	US-201214234272-A
Country	US
Kind code	B2
Filing date	Jul 25, 2012
Priority date	Jul 29, 2011
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

The invention relates to a continuous self-metered process of forming a multilayer film comprising at least two superimposed polymer layers comprising the steps of: (i) providing a substrate ( 5 ); (ii) providing two or more coating knives ( 2, 3, 4 ) which are offset, independently from each other, from said substrate ( 5 ) and/or from an adjacent coating knife to form at least one substrate gap ( 9 ) relative to the surface of the substrate ( 5 ) and at least one outlet gap ( 10 ) relative to the surface of an adjacent coating knife; (iii) moving the substrate ( 5 ) relative to the coating knives ( 2, 3, 4 ) in a downstream direction ( 6 ), (iv) providing curable liquid precursors of the polymers (I, II, III) to the upstream side of the coating knives ( 2, 3, 4 ) thereby coating the two or more precursors (I, II, III) through the respective gaps ( 9, 10 ) as superimposed layers ( 12, 13, 14 ) onto the substrate ( 5 ); (v) optionally providing one or more solid films ( 1 1 ) and applying these essentially simultaneously with the formation of the adjacent lower polymer layer, and (vi) curing the precursor of the multilayer film thus obtained; wherein a lower layer of a curable liquid precursor (I, II, III) is covered by an adjacent upper layer of a curable liquid precursor (I, II, III) or a film ( 1 1 ), respectively, essentially without exposing said lower layer of a curable liquid precursor (I, II, III).

First claim

What is claimed is:

1. Continuous self-metered process of forming a multilayer film comprising at least two superimposed polymer layers, the method comprising:
providing a substrate;
providing two or more coating knives which are offset, independently from each other, from said substrate and/or from an adjacent coating knife to form at least one substrate gap relative to the surface of the substrate and one or more outlet gaps relative to the surface of an adjacent coating knife;
moving the substrate relative to the coating knives in a downstream direction, providing two or more curable liquid precursors of the polymers to the upstream side of the coating knives thereby coating the two or more precursors through the respective outlet gaps and the at least one substrate gap as superimposed layers onto the substrate; and
curing the precursor of the multilayer film thus obtained;
wherein a lower layer of a curable liquid precursor is covered by an adjacent upper layer of a curable liquid precursor or a film, respectively, essentially without exposing said lower layer of a curable liquid precursor, wherein the method further comprises moving at least one of the coating knives relative to each other to adjust the width of the one or more outlet gaps formed between the surfaces of adjacent coating knives to be between 50 μm and 1,500 μm,
wherein the precursor of the multilayer film comprises at least two precursor layers, and at least one exposed layer is applied via one of the outlet gaps and has a thickness between 30 μm and 200 μm, wherein the thickness of the at least one exposed layer is controlled by adjusting the width of the one of the outlet gaps, whereas a total thickness of the superimposed layers is controlled by adjusting the width of the at least one substrate gap, and
wherein the liquid precursors of the polymer material are provided in one or more coating chambers essentially abutting each other and being bordered in downstream direction by the respective coating knives.

2. Process according to claim 1 , wherein the width of the one or more outlet gaps formed between the surfaces of adjacent coating knives are between 100 μm and 1000 μm.

3. Process according to claim 1 , wherein the cross-sectional profile of at least one of the coating knives at its transversely extending bottom edge facing the substrate is essentially planar, curved, concave or convex.

4. Process according to claim 1 wherein the adjacent coating knives exhibit a skewed arrangement relative to each other thereby forming the respective outlet gap between them.

5. Process according to claim 1 wherein at least one of the outlet gaps forms a narrowed outlet of the coating chambers.

6. Process according to claim 1 wherein the top layer of the stack of superimposed precursor layers is formed by an outlet gap and optionally a substrate gap.

7. Process according to claim 1 wherein a solid film is applied through an outlet gap formed between two adjacent coating knives whereby said solid film forms the downstream coating knife of the outlet gap or is applied via the upstream surface of the downstream coating knife of such gap, respectively.

8. Process according to claim 1 wherein the liquid precursors are each applied independently from each other under ambient pressure or an over-pressure, respectively.

9. Process according to claim 1 wherein the precursor layers are cured thermally and/or by exposing them to actinic radiation after they have passed the back wall of a coating apparatus.

10. Process according to claim 9 wherein at least one of the precursors comprises at least one compound having a radiation curable ethylene group.

11. Process according to claim 1 wherein the precursors of the bottom and/or top layers are substantially free of gas cavities in the form of gas inclusions resulting from stirring in gas bubbles for from blowing agents, hollow polymeric or inorganic microspheres or expandable polymeric microspheres comprising an expandable polymer shell enclosing a gaseous atmosphere.

12. Process according to claim 1 wherein the precursors of the multilayer film comprises at least 3 layers wherein at least one intermediate layers comprises a foam material comprising gas cavities in the form of gas inclusions resulting from stirring in gas bubbles or from blowing agents, hollow polymeric or inorganic microspheres or expandable polymeric microspheres comprising an expandable polymer shell enclosing a gaseous atmosphere.

13. Process according to claim 1 wherein the precursor of the multilayer film comprises at least two precursor layers wherein at least one exposed layer is applied via an outlet gap and has a thickness between 50 to 150 μm.

14. Process according to claim 13 wherein the liquid precursor formed into the exposed layer has a Brookfield viscosity of between 1,000-20,000 mPas at 25° C.

15. Process according to claim 1 wherein the precursor of the multilayer film comprises at least three layers wherein at least the top layer is applied via an outlet gap and wherein the top and bottom layer of said film independently from each other comprise each a pressure-sensitive adhesive and exhibit a thickness between 30 to 200 μm for each layer.

16. The process according to claim 1 , further comprising providing one or more solid films and applying the one or more solid films essentially simultaneously with the formation of the adjacent lower polymer layer.

17. Process according to claim 16 wherein a release liner is attached to the exposed surface of the top layer of the precursor of the multilayer film essentially simultaneously with the formation of such top layer.

18. Process according to claim 16 wherein the substrate and/or the solid film are selected from a group of materials comprising polymeric films or webs, metal films or webs, woven or non-woven webs, glass fiber reinforced webs, carbon fiber webs, polymer fiber webs or webs comprising endless filaments of glass, polymer, metal, carbon fibers and/or natural fibers.

19. The process according to claim 1 , wherein the liquid precursors of the polymer material are provided in the one or more coating chambers essentially abutting each other and being bordered in downstream direction by at least one of a front wall, one or more intermediate walls, and a back wall which are formed by the coating knives.

20. The process according to claim 1 , wherein a volume flow rate of the curable liquid precursors is not provided by a fluid metering device upstream, and the volume flow rate is variable with a substrate speed such that there is no inverse proportionality between a coating thickness of a precursor layer and a speed of the substrate.

Assignees

• Traser Steffen
• Forster Jan D
• Kuehneweg Bernd
• 3M Innovative Properties Co

Inventors

• Traser Steffen
• Forster Jan D
• Kuehneweg Bernd

Classifications

• B05D1/36

  Successively applying liquids or other fluent materials, e.g. without intermediate treatment · CPC title

• Y10T428/269

  including synthetic resin or polymer layer or component · CPC title

• B05D3/06

  by exposure to radiation (B05D3/02 takes precedence {; plasma treatment B05D3/141}) · CPC title

• B05D7/56

  Three layers or more · CPC title

• B05D3/067

  Curing or cross-linking the coating · CPC title