Laminates comprising ionomer interlayers with low haze and high moisture resistance
A laminate comprises an ionomeric interlayer sheet which, in turn, comprises or is prepared from a sodium/zinc mixed ionomer that comprises carboxylate groups and a combination of counterions that consists essentially of sodium cations and zinc cations. The sodium/zinc mixed ionomer is the neutralization product of a precursor acid copolymer. The precursor acid copolymer comprises copolymerized units of an α-olefin and an α,β-ethylenically unsaturated carboxylic acid, and it has a melt flow rate of about 70 to about 1000 g/10 min. In addition, the precursor acid copolymer, when neutralized to a level of about 40% to about 90%, and when comprising counterions that consist essentially of sodium ions, produces a sodium ionomer that has a freeze enthalpy that is not detectable or that is less than about 3.0 j/g, when determined by differential scanning calorimetry.
1. A laminate comprising at least one interlayer sheet that is laminated to one or more rigid sheets, to one or more other interlayer sheets, or to one or more film layers, said at least one interlayer sheet comprising a sodium/zinc mixed ionomer composition, said sodium/zinc mixed ionomer composition comprising a sodium/zinc mixed ionomer that is the neutralization product of a precursor acid copolymer;
wherein (a)(i) the precursor acid copolymer comprises copolymerized units of ethylene and about 20 to about 30 wt %, based on the total weight of the precursor acid copolymer, of copolymerized units of an α,β-ethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid;
wherein (ii) the precursor acid copolymer has a melt flow rate of about 70 to about 4000 g/10 min, as determined in accordance with ASTM D1238 at 190° C. and 2.16 kg;
wherein (iii) the precursor acid copolymer, being neutralized to a level of about 40% to about 90% based on the total number of the carboxylic acid groups present in the precursor acid copolymer, produces a sodium ionomer, said sodium ionomer comprising carboxylate groups and counterions, and said counterions consisting essentially of sodium cations,and wherein (iv) the sodium ionomer has a melt flow rate of about 0.7 to about 25 g/10 min and a freeze enthalpy that is not detectable or that is less than about 3.0 j/g, as determined by differential scanning calorimetry in accordance with ASTM D3418; and
(b) said sodium/zinc mixed ionomer comprises carboxylate groups and a combination of counterions; said combination of counterions consisting essentially of about 5 to about 95 equivalent % of sodium cations, and about 95 to 5 equivalent % of zinc cations, based on the total number of equivalents of carboxylate groups in the sodium/zinc mixed ionomer.
2. The laminate of claim 1 , wherein about 30% to about 90% of the acid moieties of the precursor acid copolymer are neutralized.
3. The laminate of claim 1 , wherein about 40% to about 70% of the acid moieties of the precursor acid copolymer are neutralized.
4. The laminate of claim 1 , wherein the sodium/zinc mixed ionomer has a melt flow rate (MFR) of about 0.7 to about 25 g/10 min, as determined in accordance with ASTM D1238 at 190° C. and 2.16 kg.
5. The laminate of claim 1 , wherein the precursor acid copolymer comprises about 20 to about 25 wt % of copolymerized units of the a,β-ethylenically unsaturated carboxylic acid.
6. The laminate of claim 1 , wherein the combination of counterions consists essentially of about 50 to about 95 equiv % of the sodium cations, and about 5 to about 50 equiv % of the zinc cations.
7. The laminate of claim 1 , wherein the interlayer sheet is in the form of a monolayer sheet and further wherein the monolayer sheet consists essentially of the sodium/zinc mixed ionomer.
8. The laminate of claim 1 , wherein the interlayer sheet is in the form of a multilayer sheet and comprises two or more sub-layers; wherein at least one of the sub-layers consists essentially of the sodium/zinc mixed ionomer and the other sub-layer(s) comprise a polymer selected from the group consisting of acid copolymers, ionomers of acid copolymers, poly(ethylene vinyl acetates), poly(vinyl acetals), polyurethanes, polyvinylchlorides, polyethylenes, polyolefin block elastomers, copolymers of an α-olefin and an α,β-ethylenically unsaturated carboxylic acid ester, silicone elastomers, epoxy resins, and combinations of two or more thereof; and wherein the other sub-layers, if two or more are present, are the same or different.
9. The laminate of claim 1 , wherein the rigid sheet comprises a material having a modulus of about 690 MPa or greater, as determined in accordance with ASTM D638, and the material is selected from the group consisting of glass, metal, ceramic, and polymers.
10. The laminate of claim 1 , wherein the film layer is a metal film or a polymeric film comprising one or more materials selected from the group consisting of polyesters, polycarbonates, polyolefins, norbornene polymers, polystyrenes, styrene-acrylate copolymers, acrylonitrile-styrene copolymers, polysulfones, polyamides, polyurethanes, acrylic polymers, cellulose acetates, cellophanes, vinyl chloride polymers and fluoropolymers.
11. The laminate of claim 1 , further comprising one or more other polymeric interlayers, wherein the one or more other polymeric interlayers comprise one or more materials selected from the group consisting of poly(vinyl acetals), poly(vinyl chlorides), polyurethanes, ethylene/vinyl acetate copolymers, acid copolymers, and ionomers; and wherein the other polymeric interlayers, if two or more are present, are the same or different.
12. The laminate of claim 1 , wherein the at least one interlayer sheet comprising the sodium/zinc mixed ionomer is laminated between two glass sheets.
13. The laminate of claim 1 , wherein the at least one interlayer sheet comprising the sodium/zinc mixed ionomer is laminated between a glass sheet and a polyester film; said polyester film having a surface that is adjacent to the interlayer sheet and a surface that is facing away from the interlayer sheet; and wherein surface that is facing away from the interlayer sheet is coated with an abrasion resistant hardcoat.
14. The laminate of claim 1 , which comprises n rigid sheet or film layers and (n−1) interlayer sheets, wherein (a) each of the adjacent pairs of the rigid sheet or film layers is interspaced by one of the interlayer sheets; (b) at least one of the interlayer sheets comprises the sodium/zinc mixed ionomer composition, and (c) n is an integer such that 2≦n≦10.
15. The laminate of claim 14 , which comprises an impact zone that faces to the impact force and an anti-spall zone that is firmly adhered to the impact zone and faces away from the impact force, wherein (A) the impact zone is formed by the n rigid sheets and the (n−1) interlayer sheets; and (B) the anti-spall zone comprises an additional polymer sheet and an additional film layer with a first surface of the additional polymer sheet adhered firmly to the impact zone and a second surface of the polymer sheet adhered firmly to the additional film layer.
16. The laminate of claim 15 , wherein (A) each of the n rigid sheets is a glass sheet; (B) each of the (n−1) polymer interlayer sheets comprises the sodium/zinc mixed ionomer composition; (C) the additional polymer sheet comprises a poly(vinyl butyral); and (D) the additional polymer film is a poly(ethylene terephthalate) film having a surface that is opposite from the impact zone and having a hardcoat adhered to at least a portion of the surface.