Thermally resistant and flame-retardant coating

Abstract

The present disclosure is related generally to thermally resistant and flame-retardant coating compositions and related methods of use. More particularly, this disclosure relates to thermally resistant and flame-retardant coating compositions containing at least one polycation, at least one polyanion, and at least one plasticizing salt.

Description

THERMALLY RESISTANT AND FLAME-RETARDANT COATINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 514,005, filed July 17, 2023, which is incorporated by reference as if fully set forth herein.TECHNICAL FIELD

[0002] This disclosure generally relates to thermally resistant and flame-retardant coating compositions and related methods of use. More particularly, this disclosure relates to thermally resistant and flame-retardant coating compositions containing at least one polycation, at least one polyanion, and at least one plasticizing salt.BACKGROUND

[0003] Fire-related occurrences have caused widespread property damage and injuries. It is well known that a wide range of commonly used materials are flammable. To reduce the hazards from such flammable materials, flame retardants have been developed. Such flame retardants include halogenated materials. Halogenated materials typically include brominated compounds and halogen substituted compounds. Drawbacks to such halogenated materials include the potential for harm to the environment and humans. For instance, such halogenated materials may form toxins. Other drawbacks include a lack of durability that may be typical in some instances to the brominated compounds.

[0004] In order for polymeric materials to ignite, some form of degradation must occur. As polymers thermally decompose, they break down into generally volatile constituent molecules and free radicals that enter the vapor phase and combust with atmospheric oxygen if the temperature is above the ignition temperature, or a suitable ignition source is found. Combustion is an exothermic process which recycles thermal energy back into the underlying material, resulting in more material decomposition and feeding the combustion with additional fuel. The interface region between the flame and polymer is key as this allows the volatile constituent molecules and free radicals to continue to be generate the continuation of the reaction.

[0005] In order for a material to become flame retardant, the cycle must be interrupted to stop the fuel to be added to the fire. A flame starved of fuel will extinguish. Therefore, it is important to develop materials and coatings that may act as thermally resistant and flame-retardant without the use of halogenated compounds.SUMMARY

[0006] Exemplary embodiments relate to a composition comprising: at least one polycation between about 0.1 wt% and about 20 wt%; at least one polyanion between about 0.1 wt% and about 50 wt%; and at least one plasticizing salt between about 0.1% and about 35 wt%. This embodiment or another exemplary embodiment may provide for the at least one of polycation is polyvinylamine, polyallylamine hydrochloride and combinations of polyvinylamine, and polyallylamine hydrochloride. This embodiment or another exemplary embodiment may provide for the weight percentage of polyvinylamine and polyallylamine are equal. This embodiment or another exemplary embodiment may provide for the weight percentage of polyvinylamine is between about 0.1 wt% and about 20 wt%. This embodiment or another exemplary embodiment may provide for the weight percentage of poly(allylamine) is between about 0.1 wt% and about 20 wt%. This embodiment or another exemplary embodiment may provide that the at least one polyanion comprises ammonium polyphosphate. This embodiment or another exemplary embodiment may provide that the at least one plasticizing salt comprises ammonium pentaborate tetrahydrate. This embodiment or another exemplary embodiment may provide for a crosslinker between about 0.1 wt% and about 4 wt%. This embodiment or another exemplary embodiment may provide that the crosslinker comprises tetrakishydroxymethyl phosphonium chloride. This embodiment or another exemplary embodiment may provide for about 0.1 wt% to about 30 wt% boric acid. This embodiment or another exemplary embodiment may provide for about 0.1 wt% to about 3 wt% of calcium chloride. This embodiment or another exemplary embodiment may provide for at least about 0.1 wt% to about 15 wt% of a char promoter. This embodiment or another exemplary embodiment may provide that the char promoter is pentaerythritol.

[0007] Another embodiment relates to a method for manufacturing a thermally resistant and flame-retardant multilayer laminate comprising: providing a polymeric or paper facestock layer; providing a polymeric adhesive layer; providing a polymeric top coat layer; depositing on the polymeric top coat layer a thermally resistant and flame-retardant composition; wherein the composition comprises: at least one polycation between about 0.1 wt% and about 20 wt%; at leastone polyanion between about 0.1 wt% and about 50 wt%; and at least one plasticizing salt between about 0.1% and about 35 wt%; and sandwiching the facestock layer between the top coat layer and the adhesive layer. This embodiment or another exemplary embodiment may provide that the depositing comprises spray coating. This embodiment or another exemplary embodiment may provide that the at least one of polycation of the composition is polyvinylamine, polyallylamine hydrochloride, or mixtures thereof. This embodiment or another exemplary embodiment may provide that the at least one polyanion of the composition comprises ammonium polyphosphate. This embodiment or another exemplary embodiment may provide that the at least one plasticizing salt of the composition comprises ammonium pentaborate tetrahydrate. This embodiment or another exemplary embodiment may provide that the composition further comprises a crosslinker between about 0.1 wt% and about 4 wt%. This embodiment or another exemplary embodiment may provide that the composition further comprises tetrakishydroxymethyl phosphonium chloride.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 shows the structures of several exemplary polyelectrolytes.

[0009] Figure 2 is a picture of flame testing with a 2.0s flame exposure showing performance of various Examples and Comparative Examples discussed herein.Definitions

[0010] As used herein, "gsm" means grams per square meter.

[0011] As used herein, the term "multilayer" means, with respect to laminate construction, the adhesive coated face material with one or more additional layers. Non-limiting examples of such layers to make up the multilayer include protective layers, spacing layers, adhesive layers, optical component-containing layers, metallic layers, barrier layers, release liners, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like as well as combinations thereof. The resultant multilayer laminate construction described herein can be used for a variety of applications including, but not limited to, graphics applications, such as automobile and architectural wraps; reflective applications, such as road and traffic signs, trains and other commercial vehicles, etc.; and label and packaging applications for battery labels and beyond.

[0012] The term "surface treatment region" as used herein refers to a region of material having no clear boundary. The surface treatment region typically includes a coating and extends into a region of an adjacent substrate containing both coating material and substrate material, into which the coating may permeate, diffuse, or at least partially migrate into. The term "surface treatment" refers to treatment of a surface such as a substrate surface by application of a coating which results in no clear boundary between the coating and the substrate.

[0013] As used herein, the term "halogen free" or "free of halogen" is meant to include hydrochlorides, as this is merely an acid salt resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base (e.g. an amine). Converting amines into their hydrochlorides is a common way to improve their water solubility, and shelf stability which can be desirable for substances, including those discussed herein. Further, this may extend to phosphonium compounds bound with chlorides or ionic chloride salts added as an alternative to plasticizing salts.DETAILED DESCRIPTION

[0014] In general, the present specification discloses top coat or a new protective film or laminate that has at least one major surface of a substrate treated with a material to enhance the properties of the laminate while retaining a sufficient portion of the coated material's property, such as clarity, flexibility and / or extensibility. In particular, the surface treatment proposed may be a conventional top coating or top coat or one in that a substantial portion of the material applied during the surface treatment does not ultimately remain extending above or disposed on top or proud of the upper surface of the underlying film or laminate so treated. That is to say, rather than forming a largely distinct layer with a well-defined boundary on top of the underlying film or laminate, the coating material applied during the surface treatment sits on top of or may penetrate the matrix of the underlying film / laminate and / or fills valleys or depressions on the rough surface of the underlying film / laminate. The coating material used in the surface treatment generally includes a liquid coating. A coating solution is typically a clear liquid in which the coating ingredients are either totally soluble in an organic solvent or water, or their size is smaller than the visible wavelength of light and so the coating ingredients do not scatter light. A coating dispersion refers to a coating liquid that appears cloudy either because the coating ingredients are not totally soluble in or miscible with an organic solvent or water, or their size is larger than the visible wavelength of light and scatter light.

[0015] The diffusion and formation of a gradual transitioning layer of the treatment materials into the plastic film substrate contributes largely to the retention desired film or laminate properties. This is particularly the case when the treatment material is from a protective composition as illustrated by the embodiments herein. Several mechanisms can contribute to the diffusion and formation of a gradual transition. The outermost surface of the film, specifically polymeric materials, is generally rough on a nano-meter scale. Upon treatment with the coating material, the valley areas are filled with the coating materials, which also beneficially leading to a smoother surface. In any event, at least in part due to these effects, as visible under magnification, the thickness and / or amount of the coating material from the treatment which remains above or proud of the top surface of the underlying substrate material is relatively small in view of the coating weight used to apply the treatment material. In fact, in some embodiments it may even be unperceivable.

[0016] It is reasonable to assume that an ingredient of smaller size and / or having good affinity with the plastic film would diffuse faster than an ingredient that is larger and / or having poor affinity. Since a typical coating formulation contains several ingredients that are different in size and / or in affinity / compatibility with the film, the composition of the coating materials that have diffused / migrated into the film may be substantially different from the composition of the starting formulation. This in turn leads to a new composition for the coating layer that remains above the film, different from the composition of the starting coating formulation as well.Adhesives

[0017] The laminates / constructs described herein contain one or more adhesives. The adhesive(s) can be a pressure sensitive adhesive (PSA), a non-pressure sensitive adhesive, a hot-melt adhesive, or combinations thereof. In some embodiments, the adhesive is a PSA. The PSA may be any known PSA. In some embodiments, the PSA is a solvent type adhesive, an emulsion type adhesive, or non-emulsion type adhesive. In some embodiments, the PSA is an emulsion adhesive. Hot melt PSAs may also be used. The adhesive may be acrylic or any other useful adhesive which has the hardness and adhesive properties needed for the laminates and / or adhesive coated facestocks. In certain embodiments, the adhesive should have a hardness sufficient to prevent the adhesive squeezing out of the laminate or article during processing.

[0018] Exemplary PSAs may be found in (1) Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley-lnterscience Publishers (NewYork, 1988); (2) Polymer Science and Technology, Vol. 1,Interscience Publishers (New York, 1964); (3) those described in U.S. Pat. Nos. 5,164,444; 5,183,459; and 5,264,532, all issued to Bernard, and U.S. Pat. No. 5,385,965, issued to Bernard et al; and (4) combinations thereof. The PSAs may be a solvent based or may be a water-based adhesive. Conventional PSAs, including acrylic-based PSAs, rubber-based PSAs and silicone-based PSAs may be used in the laminates / constructs described herein. In one embodiment, the pressure sensitive adhesive contains an acrylic emulsion adhesive.

[0019] In some embodiments, the pressure sensitive adhesive is prepared by polymerizing alkyl acrylates, vinyl esters, diesters of dicarboxylic acids and unsaturated acids. The alkyl acrylates typically contain from about 2 to about 12, or from about 4 to about 8 carbon atoms in the alkyl group. Examples of alkyl acrylates include, but are not limited to, ethyl, n-butyl, hexyl, 2-ethylhexyl, and isooctyl acrylates, with 2-ethylhexyl acrylate preferred. In one embodiment, the alkyl acrylates are present in an amount of at least about 35%. In some embodiments, the alkyl acrylates are present in an amount from about 35% to about 60% by weight.

[0020] The vinyl esters typically have from about 2 to about 12, or from about 4 to about 8 carbon atoms in the alkyl group. Examples of vinyl esters include, but are not limited to, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate and the like, with vinyl acetate being preferred. In some embodiments, the vinyl esters are present in an amount from about 15% to about 35% or from about 20% to about 25% by weight.

[0021] The diesters of the dicarboxylic acids include alkyl esters of unsaturated diacids, such as maleic acid or anhydride and fumaric acids. The alkyl group generally contains from about 2 to about 20, or from about 4 to about 16, or from about 6 to about 12 carbon atoms. Examples of diesters of diacids include, but are not limited to, butyl, octyl fumarate; hexyl, decyl maleate; di-2-ethylhexyl maleate; di-butyl fumarate; and di-2-ethylhexyl fumarate and mixtures thereof. In some embodiments, the diesters of diacids are present in an amount from about 20% to about 35% by weight.

[0022] The unsaturated acids generally contain from about 2 to about 12, or from about 2 to about 6 carbon atoms. Examples of the unsaturated acids include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, and the like. In some embodiments, the unsaturated acids are present in an amount up to 5% or from about 1% to about 3% by weight.

[0023] In exemplary embodiments, the coat weight of adhesives may be between 2 and 100 gsm.Release Liners

[0024] In some embodiments, the laminates described herein may include one or more release liner(s). The liner may have a first side, a second side opposed to the first side, a first edge, and a second edge opposed to the second edge. The liner may be any useful liner which provides necessary support and release properties. The liner may be made of, or from, a variety of materials including, but not limited to, paper or polymer film liners. In one embodiment, the caliper of the paper is sufficient to die cut the resulting laminate or article. For example, liner calipers can range from about 18 mm to 23 mm for PET liners. In one embodiment, the liner has lay flat properties. In some embodiments, the liner has a machine glaze or finish. In some embodiments, the liner has a silicone hold out layer. The hold out layer provides adhesion between the release coating and the release liner. The silicone holdout layer also prevents the silicone release coating from soaking into the liner.

[0025] In the instance of paper liners and other absorbent liners, these liners have a moisture content. The moisture content may be varied and changed in various ways in order to promote, prevent, or optimize patterning of the liner based on this moisture content. Additional discussion will be had with respect to the methods below.

[0026] In some embodiments, the release liner includes a liner having a release coating. The release coating of the release liner provides a releasable bond with the PSA or other adhesive. The release coating may be any composition which provides a desired releasable bond strength.

[0027] In one embodiment, the release coating is a silicone release coating. The release coating can be prepared by curing silicone polymers in the presence of a control release agent. In some embodiments, the control release agent is a copolymer of a monofunctional silicone unit of the formula RsSiOi / j and tetrafunctional silicone units SiO4 / 2 wherein R is an alkyl or alkenyl group. In one embodiment, the alkyl or alkenyl groups contain from about 1 to about 12, or from about 1 to about 6 carbon atoms. Non-limiting examples of alkyl and alkenyl groups include methyl, ethyl, propyl, butyl, hexyl, ethenyl, propenyl, butenyl and hexenyl groups.

[0028] The control release agent is typically reacted with a polysiloxane. The polysiloxane may be any polysiloxane which is useful in forming a release coating. Examples of useful polysiloxanes include, but are not limited to, vinyl terminated, hydroxy terminated and epoxy terminatedpolysiloxanes. In one embodiment, the polysiloxane is a functional polydialkyl siloxane, wherein the alkyl group contains from about 1 to about 6 carbon atoms. The alkyl groups independently include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl groups or mixtures thereof. In one embodiment, the alkyl or alkenyl group contains from 1 to about 12, or from 1 to about 6 carbon atoms. The polysiloxane typically has a viscosity average molecular weight of greater than 300,000 centipoise (cps). In another embodiment, the polysiloxane has a viscosity molecular weight from about 300,000 to about 1,000,000 or more. The polysiloxane may be represented by the formula (I):RO((Si(R)2O)x)-Si)-R (I) wherein each R is independently as defined above and x is an integer.

[0029] In some embodiments, the release coating is prepared with a cross linking agent. In some embodiments, the cross linking agent is a reactive polysiloxane, such as a polydialkyl or polyhydroalkyl siloxane. The alkyl groups are the same as those described above.

[0030] The release coating may be applied in a solvent, solvent-less or emulsion form. The release coating may be cured by any known curing process, e.g. thermal, radiation, etc., to form the release coating. The curing may be catalyzed by silicone soluble complexed compounds of Group VIII transition metals, such as platinum.

[0031] Commercially available release agents include, but are not limited to, GE SS-4335, a silicone release agent in unreactive solvent. Commercially available polysiloxanes include, but are not limited to, GE SS-4331, a vinyl terminated polydimethyl siloxane. Commercially available linking agents include, but are not limited to, GE SS-4300C, a polymethyvinyl siloxane. Exemplary catalysts include, but are not limited to, SS-8010 catalyst in toluene. These materials are available commercially from General Electric Company's Silicone Products Division. Similar silicone products are available under the tradename Syl-off from Dow Corning Corporation.

[0032] It will be understood that the present subject matter is not limited to any of the noted release coatings or agents, and instead includes nearly any release coating or agent suitable for the intended end use application. Furthermore, although the present subject matter has been described in association with release liners, it will be appreciated that appropriately configured carrier films and other members could be used instead of release liners.Face Material

[0033] Suitable face materials include, but are not limited to, synthetic papers such as polyolefin type and polystyrene type; various plastic films or sheets such as polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyurethane, polymethacrylate and polycarbonate. Additional examples of suitable face materials include paper and cardboard. The face material may be, or may include, a multilayer polymeric sheet. The multi-layers may be coextruded, or the multi-layers may be laminated together. In one embodiment, the face material includes both co-extruded multi-layers and laminated multi-layers. In addition, a white opaque film may be formed by adding a white pigment to one or more of the aforementioned synthetic resins and used as the face material. In one embodiment, a foamed film is used as the face material. The foamed film may be formed by a conventional foaming operation. In another embodiment, the face material may be a laminated body formed by combining a plurality of single layered sheets composed of the above listed materials. Examples of such a laminated body may include the combination of cellulose fiber paper with synthetic paper, and a laminated body of combined cellulose fiber paper with a plastic film or sheet. In another suitable embodiment, the face material includes coated and uncoated papers, metalized papers, aluminum foil, laminated paper and paper with a polymeric material extruded onto the surface of the paper. In certain versions, the face material can be coated with a liquid absorbent material. The selected face material may be porous or semi-porous. The face material may exhibit certain visibility characteristics such as opaqueness, color, and / or brightness. The face material may include water or other liquid absorbency properties. The face material may be electrically conductive and / or include electrically conductive coatings or regions. A wide array of commercially available face materials can be used such as for example those available under the designation TESLIN.

[0034] The thickness of the face material is optionally determined with reference to application specific criteria. Such criteria may include the desired end use. In one embodiment, the sheet thickness is in a range of from about 10 pm to about 300 pm. In another embodiment, the sheet thickness is in a range of from about 20 pm to about 200 pm. In still another embodiment, the sheet thickness is in a range of from about 30 pm to about 150 pm. Optionally, a primer treatment or a corona discharging treatment or a plasma treatment may be used on the face material to increase a bonding strength between the face material and a dried topcoat composition to be formed on a surface of the face material.

[0035] In certain embodiments described herein, the face material exhibits one or more functions or functional characteristics. For example, the face material may be selected to enable orpromote an indication such as a visual indication of a liquid, outgassing such as directing or allowing flow of air or gas across a thickness of the face material, water or liquid retention within the face material, electrical discharge or conductivity of the face material, chemical delivery across a thickness of the face material, passage of sound across a thickness of the face material, and / or combinations of these functions or characteristics.Optional Layers

[0036] The adhesive coated face material and / or laminates described herein can include one or more additional layers or components. Non-limiting examples of such layers include protective layers, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like.Laminate Properties

[0037] The laminates described herein may have specific and useful properties or functionalities. In some embodiments, the techniques described herein enable formation of laminates in which transfer, propagation, and / or migration of liquid, gas, sound waves, electrical current, and / or other agents or elements can occur and is controlled across or through the laminate in a Z-direction. The reference to "Z-direction" as made herein refers to a direction across a thickness dimension of a laminate or portion thereof, and thus references to "X-direction" and / or "Y-direction" refer to directions perpendicular to the Z-direction and correspond to width and length dimensions of the laminate.

[0038] Non-limiting representative examples of laminates having certain functionalities which are provided by the present subject matter include liquid indicator laminates, outgassing laminates, water absorbent laminates, sound channeling laminates, electrically conductive laminates, and laminates having combinations of these functionalities and / or laminates having combinations of one or more of these functionalities and additional functionalities.

[0039] For example, a liquid indicator laminate can be produced such that the speed of the indicator color change is linked to the facestock selection and porous adhesive properties. A discontinuous structure, such as resulting from pores in the adhesive layer or region(s), can allow, forexample, liquid to channel through the discontinuous adhesive from one side of the adhesive to the other side and create a permanent discoloration when a dye or other agent in a functional coating in the laminate is dissolved.

[0040] In one embodiment, a liquid indicator laminate is provided. The speed or rate of the indicator color change is linked to the facestock properties such as for example absorbency of liquid, and porosity of the pattern adhesive in the Z-direction. The indication typically is irreversible and can be measured by color change or by a simple visual comparison.

[0041] The discoloration of a face or region of the laminate can be measured and quantified by optical change, such as by CIE Lab or by a simple visual comparison. The discoloration can be permanent or nonpermanent. The discoloration can also be temporary and revert to an initial state after passage of a period of time. In some embodiments, the period of time is predetermined.

[0042] This phenomenon of transport through discontinuities in an adhesive in the Z- direction can be implemented in other label applications and particularly pressure sensitive adhesive labels, such as for example, labels for outgassing substrates such as by air channeling in the Z-direction, moist substrate labeling such as by liquid channeling in the Z-direction, electrical discharge in the Z- direction, chemical delivery from one layer to another in the Z-direction, and / or sound channeling in the Z-direction. This phenomenon enables passage, transfer, and / or migration of a medium or agent from one side of an adhesive region of a laminate, to another side of the adhesive region. Although medium penetration or transport is noted as being in the Z-direction, it will be understood that the present subject matter is not limited to such and may also include penetration / transport in the X- direction and / or Y-direction.

[0043] In some embodiments, the laminates described herein include a layer or region of a secondary adhesive. The secondary adhesive is typically utilized to adhere the laminate to a substrate of interest. The secondary adhesive may contain one or more adhesives which are the same or different than the adhesive of the patterned or porous adhesive. Description of representative examples of secondary adhesives are provided herein. In such an adhesive configuration, the primary adhesive may be coated onto the facestock, the secondary adhesive may be coated onto the release liner, and the coated adhesive and release liner may be laminated together such that the primary and secondary adhesives are in direct contact with each other. Alternatively, or additionally, both the primary and secondary adhesive may be coated on the facestock or the release liner, then laminatedtogether. It is contemplated that the layering of the primary and secondary adhesive relative to the facestock and the release liner may be either facestock, primary adhesive, secondary adhesive, and release liner or facestock, secondary adhesive, primary adhesive, release liner. Regardless of the order of primary and secondary adhesive, it is contemplated that at least one of the primary and secondary adhesive is patterned, taking into consideration that the other adhesive may be continuous.

[0044] In some embodiments, an array of different arrangements of layers and components may be utilized. In some embodiments using the patterned adhesive, e.g., the layer of discontinuous adhesive, that layer is disposed between a functional facestock and a liner or functional layer. And in the liquid indicator laminates, the patterned adhesive may be disposed between the functional facestock and the layer or region of functional agent that is sensitive to liquid passing through the laminate. And, in the liquid indicator laminates, the layer or region of the functional agent may be disposed between the patterned adhesive and the carrier layer.

[0045] Utilization of the techniques and features described herein enable production of adhesive laminates and / or adhesive coated face materials with fluid / air management characteristics, controlled removability, and / or unique thermal and / or electrical conductivity. In addition, use of these techniques and features enable reductions in materials, e.g., adhesives, and thus enable cost savings. However, it will be understood that the present subject matter includes the adhesive coated face materials and laminates described herein which are formed by other methods than the methods described herein.Top Coat Formulation and Application

[0046] In exemplary embodiments discussed herein, the top coat coating is deposited on the substrate by any suitable method. In embodiments, the suitable method includes any suitable coating technology. Embodiments include depositing the coating on the substrate by any suitable liquid deposition method. Without limitation, examples of suitable methods include bath coating, spray coating, slot coating, spin coating, curtain coating, gravure coating, reverse gravure print coating, reverse roll coating, knife over roll (i.e., gap) coating, metering (Meyer) rod coating, air knife coating, or any combinations thereof. Bath coating includes immersion or dip in the aqueous solution. In an embodiment, the coating is deposited by bath in the aqueous solution. In other embodiments, the coating is deposited by spray of the aqueous solution.

[0047] This disclosure specifically relates to polyelectrolyte complex (PEC) coatings can be deposited on film substrates using an application of polyelectrolyte complex coacervate. Solutions, including this one, have used a "onepot" aqueous solution. This process produces coatings with comparable flame retardant (FR) properties to those obtained using the layer-by-layer (LbL) assembly approach while using far fewer processing steps. By controlling the electrostatic interactions between dissolved polyelectrolytes, stable polymer solutions can be deposited and cured.

[0048] To avoid the additional processing step incurred from a buffer treatment, this process can be further simplified by creating a polyelectrolyte complex coacervate to deposit all of the necessary ingredients for a flame-retardant coating in a single step. Coacervates are a condensed phase with liquid-like droplets, usually formed with oppositely charged polymeric molecules. They have been studied extensively in colloid and interface science for their remarkable material properties. The coacervation phenomenon exists through mixing two polyelectrolytes of complementary charge which typically results in a solid polyelectrolyte complex precipitated from solution, but the ionic interactions between polymers can be screened by the addition of salt. This results in three potential 'phases' for polyelectrolyte mixtures: a solid complex, viscous coacervates with high polymer concentration, and solutions where the ionic crosslinks are entirely screened by added salt. The coacervate can be applied by rod / bar coating or flexographic printing to yield a conformal flameretardant coating. This method has been shown to impart gas barrier properties on PET film. In addition, polyelectrolyte complexes deposited in two steps have been shown to impart flame retardant properties to a variety of textiles. In both cases, the resulting coatings have demonstrated properties comparable to LbL coatings with much less complexity.

[0049] It was hypothesized that coacervates comprised of polyelectrolytes utilized in flame retardant PEC / LbL coatings would be effective flame-retardant treatments for PET film. Figure 1 shows the structures of several exemplary polyelectrolytes. Initial work focused on the development of flame retardant coacervates comprised of polyamines (e.g. polyethylenimine or PEI and polyvinylamine or PVAm) and sodium polyphosphate (or poly(sodium phosphate), PSP). It was discovered that while PEI / PSP coacervates form relatively effective coatings, there is no means to convert these coacervates back into solid complexes once they were coated (which is a barrier to coating durability).

[0050] It was determined that PVAm / PSP coacervates, which can form a solid complex by altering salinity with the ability to accept several synergistic additives can be incorporated into them which made them an ideal candidate for developing a halogen-free flame-retardant treatment for PET film.Then, a combination of PVAm / APP / ammonium pentaborate (APB) with APB acting as the plasticizing salt was tested. Following several formula modifications, PAAm / APP / APB crosslinked with tetrakis(hydroxymethyl) phosphonium chloride (THPC), consistently achieves a VTM-0 rating at a weight of 22 gsm comparable to a control, known as the Control system and below as Comparative Example 2.

[0051] Exemplary polycationic materials of the present disclosure include, but may not be limited to amine and imine containing compounds. Specifically, exemplary embodiments may include PVAm, PAAm, and PEI. In exemplary embodiments, at least one polycationic material is used and the amount of polycationic materials is between about 0.1 wt% and about 20 wt%. At times, when mixtures of polycationic materials are used in exemplary embodiments, the weight percentages of each may be identical. For example, a mixture of PVAm and PAAm may each have an equal weight percentage of about 0.05 wt% and about 10 wt% to equal a total of about 0.1 wt% and about 20 wt% in the composition.

[0052] Exemplary polyanionic materials of the present disclosure include, but may not be limited to polyphosphate compounds. Specifically, exemplary embodiments may include PSP and APP. In exemplary embodiments, at least one polyanionic material is used and the amount of polyanionic materials is between about 0.1 wt% and about 50 wt%.

[0053] Exemplary plasticizing salts of the present disclosure are non-halogenated. Specifically, in an exemplary embodiment APB is used as a plasticizing salt. In exemplary embodiments, at least one plasticizing salt is used and the amount of plasticizing salt is between about 0.1 wt% and about 35% wt%.

[0054] Other additives can be optionally used in different exemplary embodiments. For example, a solvent or carrier can be added to specific embodiments. For example, in certain embodiments, water can be used in an amount between about 0.1 wt% and about 70% wt%

[0055] Further, in additional embodiments a crosslinker could be added. In exemplary embodiments the crosslinker is tetrakishydroxymethyl phosphonium chloride and added in an amount between about 0.1 wt% and 4 wt%.

[0056] In further embodiments, a crystalline inhibitor is added to the composition. In exemplary embodiments the crystalline inhibitor is boric acid and it is added in an amount between about 0.1 wt% to about 30 wt%.

[0057] In further embodiments, an ionic salt may be added. In such embodiments, sodium chloride, calcium chloride, magnesium chloride, and mixtures thereof may be added. When used, the ionic salt is in an amount between about 0.1 wt % and about 3 wt%. In other embodiments, various multivalent salts may be used as they can act as an ionic crosslinker between negatively-charged segments in the coacervate.

[0058] In further embodiments, a char promoter may be added. In such embodiments, pentaerythritol may be the added char promoter. When used, the char promoter is in an amount between about 0.1 wt% and about 15 wt%.

[0059] Percentages of the compounds discussed above can be either in the wet or dry preparation. The wet preparation includes an amount of water, solvent, or carrier soon after coating so that the mixture can be sufficiently mobile for coating applications. The dry preparation is what is left once the wet coating has been subject to drying, either through an external heater or latent drying conditions after coating. Depending on the amount of water initially included, the percentages can be derived from the water content. For example, if 50 wt% water is used in the wet preparation, the dry preparation would have double the concentration of the remaining ingredients.

[0060] All solutions were prepared using 18 MO deionized (DI) water. Polyethylenimine (Mw=25,000 g / mol), hydrochloric acid (HCI, 37%), sodium hydroxide (NaOH, 98%), APB (99%), sodium chloride (NaCI, ACS reagent), THPC (80%), glutaraldehyde (GA, 50 wt% in solution), boric acid (BioReagent, 99.5%), calcium chloride, urea (ReagentPlus, 99.5%), ammonium phosphate dibasic (98.0%), pentaerythritol (PER, 98%), and sodium metasilicate were purchased from Sigma-Aldrich (St. Louis, MO). Polyvinylamine (PVAm) was provided by Solenis (product name Xelorex-1300NA). Ammonium polyphosphate (soluble APP, trade name APP-W) was purchased from Century Multech (Flushing, NY). Poly(allylamine) hydrochloride (PAAm) was purchased from Beckmann-Kenko (Bassum, Germany). Vermiculite clay (VMT) was purchased from Specialty Vermiculite Corp. (Cambridge, MA). Montmorillonite clay (MMT) was purchased from BYK Additives Inc (Wesel, Germany). Poly(ethylene oxide) (PEO, MW=4,000,000 g / mol) was purchased from Polysciences (Warrington, PA). Divinyl sulfone (DVS, 96%) was purchased from TCI America. Polyethylene terephthalate (PET) film (25.4 pmthick) was provided as a substrate for testing by Avery Dennison (AD). A commercially available flame retardant treated PET (referred to as Control) was provided to compare against formulations contained herein.

[0061] The resultant coating may be placed on either side of a substrate desired to be protected as fire resistant. While it is referred to as a top coat, this may be a coat on either of the faces of the material. For example, in certain embodiments, the top coat will be placed on the inside of the material as the possible fire may come from the inside location. In other embodiments, it may be placed on the outside of the material as the fire risk may present itself from the outside. In another embodiment, it may be placed on both sides in order to protect from the risk of fire in both directions.Coacervate Preparation

[0062] Separate, equal mass solutions of PVAm, PAAm, or a combination of the two (15 wt%) and APP (45 wt%) were prepared and rolled to homogeneity. APB was added into the polycationic solution and dissolved as much as possible before pouring in the APP solution and agitating to homogeneity (yielding a solution of 7.5 wt% PVAm or PAAm and 22.5 wt% APP). The mixture was then placed in a 70 °C oven to anneal for ~72 hours, after which time the oven was turned off and the mixture was allowed to slowly cool and phase separate overnight. The molarity of the APB in solution is reported as moles of APB per kg of polyamine / polyphosphate mixture (i.e. a solution reported as 1 M APB is 273.1 g APB added to 1 kg of 7.5% polyamine / 22.5% polyphosphate). The dilute, polymer-poor phase of the coacervate was separated from the dense, polymer-rich phase. Additives were incorporated into the coacervate by first adding the solid additive into a scintillation vial, and then pipetting in the appropriate amount of coacervate. Mixtures were then vortexed at 3000 rpm following one hour of heating in a 70 °C oven.Coating Preparation

[0063] PET film was taped and drawn taut over a glass plate and then corona treated (BD-20C, Electro-Technic Products, Inc., Chicago, IL) prior to application of a primer layer of 1 wt% PEI with a 2- mil gap bird bar (wet thickness 25.4 pm, Gardco AP-B5358, Paul N. Gardner Company, Pompano Beach, FL). The entire plate / coated PET assembly was then dried in a 70 °C oven for 20 minutes. The coacervate mixture was then applied to the surface with the same bird bar coater, either with a 2-mil or 1-mil gap. The coating was allowed to dry for one hour before testing or application of a topcoat.Crosslinkers and other topcoats were applied via spray coating using a Yattich paint sprayer (Colorado Springs, CO) and allowed to dry before testing.

[0064] Coat weight was measured by taring a 1" diameter circle of PET (from a hammer-driven hole punch, McMaster-Carr, Elmhurst, IL). The weight of a separate 1" diameter circle of coated PET was then obtained to determine the weight of the coating in units of gram / m2 (gsm). Thickness measurements of coated PET were taken using a Mitutoyo Digimatic Indicator (Aurora, IL), but this measurement is much less reliable than the gsm values.UL-94 VTM (ASTM D4804-19) Sample Methodology

[0065] A sample was prepared in accordance with ASTM D4804-19,9 which is a standardized testing method for determining the flammability of nonrigid solid plastics. A 20 x 5 cm sample of coated PET is wrapped around a 13 mm diameter rod and the lower end of the vertically hanging sample is exposed to a 20 mm methane flame for two 3-second applications. The afterflame was recorded as the time the sample remained ignited after the removal of the flame.

[0066] Cotton balls were placed underneath the hanging sample to monitor any melt dripping of the samples. To achieve the best rating (VTM-0), a sample must have an afterflame of < 10 s, no cotton ignition, and the flame cannot travel the entire length of the sample. A VTM-1 rating can be achieved with the same ignition and consumption conditions, but the afterflame time cannot exceed 30 s. Finally, an unrated sample indicates that the entirety of the sample was consumed by the flame and the cotton ignited from flaming particles or drops.Mini Flame Test

[0067] A substantially planar sample comprising a front face and a rear face is provided. This sample is then attached at its rear face to an adhesive component. The adhesive component is then also adhered to a flammable layer with a front face and a rear face. The adhesive component touches the rear face of the sample 102 and the front face of the flammable layer. The sample, adhesive component and flammable layer are together a sample construction. The sample construction is then attached to a frame. At least a portion of the sample construction is attached to the frame and at least a portion is not attached to the frame. The sample construction is then exposed to a flame source that is perpendicular to the front face of the sample.

[0068] In one embodiment, the sample is generally a laminate structure. In another embodiment it is a label material. The sample is cut out or pressed out into a substantially circular shape and has a diameter between about 0.5 and about 1.5 inches.

[0069] In one embodiment the adhesive can be any adhesive. In other embodiments, the adhesive is a pressure sensitive adhesive. In one embodiment the flammable layer is made of filter paper. In this or another embodiment, the flammable layer is made of cellulose. In a specific example, the flammable layer 106 is a Whatman® paper filter #3 (by Cytiva Marlborough, MA, USA). The flammable layer is cut out or pressed out into a substantially circular shape and has a diameter between about 0.25 and about 1.25 inches.

[0070] In the exemplary embodiment the frame is aluminum, but may be any metal or alloy that has a melting point above 400°C. The frame includes at least one aperture, and in the exemplary embodiment the aperture is circular in nature. A diameter of the at least one aperture is less than the diameter of the sample and of the flammable layer. In the exemplary embodiment, the diameter is between about 0.25 and about 0.75 inches. Further, in the exemplary embodiment, a ratio of the diameter of at least one aperture and the diameter of the sample is between about 1:6 and about 2:3 and a ratio of the diameter of the diameter of at least one aperture and the diameter of the flammable layer is between about 1:5 and about 1:1. Each of the at least one aperture, the sample and flammable layer, all being circular are also concentric with respect to one another. In one embodiment, the flame source is a flame jet. In an exemplary embodiment, the flame source is applied to the sample between about 1 and about 3 seconds. In another embodiment, the flame source is applied to the sample at about 2 seconds.

[0071] Further, a system for testing may include a timer operatively connected to a switch and a solenoid. The switch is then operatively connected to a flame source, in this case a torch, while the solenoid is operatively connected to a gate. The timer is set to a value of seconds. This value of seconds will trigger the switch prior to the time frame beginning to begin the flame from the flame source. Then, the gate can be activated by the solenoid and expose a sample to be tested. Then, when the timer reaches its value, the switch is operative to turn off the flame source while the solenoid will move the gate back to its starting position.

[0072] An exemplary method comprises providing a substantially planar sample comprising a front face and a rear face; adhering with an adhesive the sample to a substantially planar flammable layer comprising a front face and a rear face at the front face of the flammable layer to the rear face of the sample to result in a sample construction; attaching the sample construction to a frame, where at least a portion of the sample is attached to the frame and at least a portion is not attached to the frame; exposing the sample construction to a flame source substantially perpendicular to the front face of the sample for a period of time; removing the flame source; inspecting the label material for the presence of fire damage; and inspecting the rear face of the flammable material for the presence of fire damage.

[0073] An exemplary embodiment provides for 1" diameter circle of coated PET and PSA were punched out using a hammer-driven hole punch. A %" diameter circle of filter paper (Whatman Filter #3, 387 pm, acquired from VWR) was punched out using a craft hole punch. The PSA was applied to the coated side of the PET and the release liner was removed. The PSA was then adhered to the filter paper and the system was mounted in the sample holder. The sample holder was placed into a position in which the middle of the sample circle was exposed to the tip of the flame. The flame exposure time (2.0 s) was automated by a digital timer, which was provided by Avery Dennison.Example 1 - Base Recipe PVAm / APP / APB Coacervate

[0074] A 7.5% PVAm / 22.5% APP / 0.5 M APB was made as a base recipe for a starting point for further experimentation and is expressed as Example 1. The coacervate coating alone was tacky and had a VTM-l rating in UL-94 flame testing.Example 2 - Base + TH PC

[0075] An addition of 1% TH PC as a topcoat (deposited via spray coating) resulted in a non-tacky coating and improved flame performance. The crosslinked PET coating yielded a VTM-0 rating, with an average afterflame of ~4.5 sec. Results are expressed in Table 1, below. Improvements to the base recipe were made, including a variation in topcoat and incorporation of known flame-retardant additives into the coacervate, to further attempt to improve the flame performance of the coated PET.Example 3 - VMT

[0076] It was hypothesized that incorporation of vermiculite clay (VMT) into the THPC crosslinking solution could improve flame performance. Unfortunately, this was not the case. Therefore, it was further hypothesized that the addition of the clay layer after the deposition of the crosslinker could further improve the flame performance of the coating and maintain the reduction in tackiness. Thus, Example 3 was prepared by A 1% VMT solution was subsequently sprayed onto a dried crosslinked coating. This resulted in a hazy brown coating that was not tacky. However, the addition of VMT as a topcoat resulted in a worsened flame performance (VTM-1), as seen in Table 1 below.Example 4 - GA Crosslinked

[0077] Other crosslinking agents were explored as alternatives to THPC, including glutaraldehyde (GA) and divinyl sulfone (DVS), as they have been shown to successfully crosslink other polyamines. DVS did not reduce the tackiness of the coacervate coating, even with variation in concentration and curing temperature. The goal of the crosslinking agent was to provide a reduction in tackiness, while contributing to improved flame performance. DVS was unable to reduce the tackiness of the coating, so focus shifted to GA as a crosslinking agent.

[0078] Following the application of 1% GA, there was a reduction in tackiness, but the afterflame time was over 30 s in UL-94 flame testing, which resulted in an unrated VTM rating, as shown as Example 4 in Table 1. This confirms that THPC is the ideal crosslinking agent, as it both reduces tackiness and improves the flame-retardant behavior of the coating.Example 5, 6, and 7 - Fire Resistant (FR) additives

[0079] Attempts of incorporating additional intumescent ingredients into the coacervate revealed that guanidine hydrochloride, a common FR blowing agent, did not significantly improve the flame performance of the coating and is now shown. However, other additives (carbon and / or acid sources) have the potential to contribute to the intumescent behavior of the film.

[0080] Pentaerythritol (PER, char promoter) as Example 5, ammonium phosphate dibasic (acid source) as Example 6, and urea (blowing agent) as Example 7 were each independently investigated as coacervate additives to improve the flame performance of the coacervate coating. All additives were added into the coacervate at a concentration of 5 wt% in wet coacervate (~10% dry basis). The integration of ammonium phosphate and urea resulted in transparent, tacky films and did notsignificantly improve flame performance. The addition of PER yielded an opaque, rigid coating that was slightly less tacky with an improved flame performance compared to the neat coacervate coating. At the time, the opacity of this coating eliminated PER as a viable FR additive, but it could potentially be incorporated into the current "best" coacervate system to improve char formation and flame performance.Comparative Example A and B

[0081] Comparative Example A is neat PET while Comparative Example B is a commercially available FR film from Control of unknown composition or the Control coating.Table 1 - UL-94 Test Results* Unrated due to cotton ignitionExample 8 and Example 9 - Wet-Wet vs. Wet-Dry Processing

[0082] With the addition of a topcoat improving the flame performance of the coated PET, identifying the best processing method is vital. Spray coating was determined very effective way to apply a topcoat to coated PET (compared to dip-coating). Therefore, it was prudent to determine the viability of "wet-wet" vs "wet-dry" processing.

[0083] In wet-dry processing, the primed PET is coated with the coacervate and allowed to completely dry in a 70 °C oven (~30 min) before applying the topcoat via spray coating. This is shown in Table 2 as Example 8.

[0084] In wet-wet processing, the coated PET was set in the oven for 5 min to partially dry prior to spraying to promote diffusion of the topcoat into the coacervate coating. This is shown in Table 2 as Example 9.

[0085] As shown in Table 1, the wet-wet topcoat application method does not significantly improve the flame performance of THPC-crosslinked PVAm / APP / APB. This could be due to the pressure of the liquid spray disrupting the coating, causing nonuniformity. This, along with ease of production, is why wet-dry processing was chosen as the topcoat application method.Table 2Examples 10-13 - Variations in Base Coacervate Recipe

[0086] PVAm / APP / APB crosslinked with THPC using wet-dry processing has yielded the most promising flame results compared to the Control coating, with low afterflame times and VTM-0 ratings. However, other modifications can be made to the coating system to further improve coating durability and flame performance.

[0087] Specifically, boric acid proposed and was incorporated into the base coacervate at different weight ratios in an attempt to reduce coating crystallization. Finally, coat weights and thicknesses of each coating were reported to ensure that the coating was within the given targets.

[0088] Boric acid was added to PVAm / APP / 0.5 M APB in a 4:5 wt% ratio as Example 10 and as a 1:5 wt% ratio as Example 11 (boric acid:APB) to reduce the crystallinity of the resulting coating. It was found that the 1:5 wt% had better coacervate formation and improved flame performance (VTM-0) compared to 4:5 wt% (VTM1), as shown in Table 3. However, the incorporation of boric acid into the coacervate did not lead to a significant reduction in crystallinity. Boric acid was also incorporated as a topcoat to the PVAm / APP / APB coacervate, but it did not prevent crystallization.

[0089] Poly(allylamine) hydrochloride (PAAm) was substituted for poly(vinylamine) in identical concentrations to compare polyamine identity to coacervate formation, coating crystallinity differences, and flame performance. The resulting PAAm / APP / 0.5 M APB coacervate was more viscous compared to its PVAm counterpart, which led to an extremely brittle coating. However, the PAAm / APP / APB coacervate was not tacky, did not have any crystallization issues, and had excellent flame performance, yielding a VTM-0 rating for the neat coacervate. To mediate the viscosity and brittleness, the concentration of APB was reduced to 0.25 M, which made for easier application and resulted in a non-tacky coating with equally great flame performance, shown in Table 3 as Example 12.

[0090] Since the PAAm / APP / APB recipe showed such promising results, a combination of PAAm and PVAm in different ratios (1:1, 1:2, 2:1) with a total concentration of 7.5 wt% was evaluated. Of the varying ratios, 2:1 PVAm:PAAm was the only system that displayed clear phase separation. The polymer-rich phase was less viscous relative to previously successful coacervates, indicating that there was likely less material in the solution. As shown in Table 3 as Example 13, the resultant film had a much lower coat weight and poorer flame performance than PAAm / APP / APB. Even with high coat weight, altered APB concentration, and crosslinking, the flame performance of the coating was not improved.Table 3 - UL-94 Test Results for Different Base RecipesExample 14 and Example 15 - Improved Coacervate

[0091] After evaluating the flame performance of the various modified coacervate recipes, it was determined that PAAm / APP / 0.25 M APB had the best flame performance and would be considered the "base recipe" moving forward. As a way to normalize and simultaneously reduce coat weight and thickness for these films, a 1-mil gap (Example 14) was used to apply the coacervate, as opposed to a2-mil gap (Example 15). Similar to the PVAm / APP / APB system, various topcoats and additives were assessed with the new PAAm / APP / APB recipe to optimize coating performance.Examples 16-20 - Variations of the Topcoat

[0092] It was observed with the previous base recipe (PVAm / APP / APB) that the addition of THPC crosslinker as a topcoat led to a significant improvement in the flame performance of the coating. It was expected that THPC would have the same effect on the new base recipe, PAAm / APP / APB. Although the decrease in coat weight and film thickness due to the thinner bar gap did slightly decrease the flame performance of the neat coacervate, the addition of 1% THPC as a topcoat yielded excellent flame performance with a similar coat weight and thickness to the neat coacervate coating. As shown in Table 4 below. The THPC crosslinked PAAm / APP / APB with a 1-mil gap (Example 16) had very short afterflame times (~1.5 s each), yielding a rating of VTM-0.

[0093] The same coacervate deposited using a 2-mil gap (Example 17) did have a slightly better flame performance, but the large difference in film thickness made it difficult to compare against the neat coacervate performance. The PAAm / APP / APB crosslinked with THPC is the best performing coating thus far, with afterflame times nearly identical to the Control coating, a thickness of only 13 pm, and a coat weight of 22 gsm.

[0094] Initially, NaCI and CaCI2were incorporated into the coacervate as additives. After the addition of NaCI did not improve the flame performance of the coating, and CaCI2resulted in complexation of the coacervate ingredients, the calcium salt was explored as an alternative topcoat to THPC. At an identical concentration (1 wt%), the CaCI2-topcoat coacervate did have an improved flame performance compared to the neat coacervate. Similar to the neat coacervate and THPC systems, the thinner coating of the 1-mil gap (Example 18) had a slightly worse flame performance compared to the 2-mil gap coating (Example 19). However, using a smaller gap yields a more consistent coat weight, thickness, and flame performance, which simplifies the comparison of coating performance. From this result, it is apparent that the addition of the CaCI2is contributing to the flame performance of the coating, as demonstrated by the VTM-0 rating, but the THPC-crosslinked coacervate coating still out-performed the CaCI2 topcoat with a nearly identical coat weight and film thickness.

[0095] Since THPC and CaCI2both led to an improved flame performance of the coacervate coating, it was hypothesized that the combination of the two ingredients applied as a single topcoatcould further improve the coating's flame performance. As shown as Example 20 in Table 4, the addition of a 1:1 wt% ratio of THPC+CaCL as a topcoat did not perform as well as the topcoat containing the individual ingredients. Even at different ratios (1:2, 1:10) the addition of a second ingredient in the topcoat did not result in an improved flame performance. Finally, THPC and CaCL were applied in subsequent steps, resulting in a total of 3 layers (not including the priming layer), which did not significantly improve the performance of the coating.Table 4 - UL-94 Test Results for PAAm / APP / 0.25M APB base recipe with TopcoatsExamples 21-24 - Coacervate Additives

[0096] The PAAm / APP / APB THPC-crosslinked coating has demonstrated excellent flame performance in UL-94 testing, but the coating itself is somewhat brittle and prone to minor cracks. While this does not alter the fire properties of the coating, this could lead to other difficulties with the appearance of a final product. To reduce the brittleness / shrinking of the coating, flame retardant fillers, such as poly(ethylene oxide) (PEO) (Example 21), montmorillonite clay (MMT) (Example 22), and sodium silicate (Example 23), were each independently incorporated into the base coacervate (0.25M of APB) at a concentration of 1 wt%. Both PEO and MMT integrated well into the coacervate, and all three coacervate coatings were transparent and tacky. As shown in Table 5 below, none of the additive recipes obtained a VTM-0 rating, but the addition of 1% MMT into the coacervate with had the best flame performance with a significantly lower coat weight compared to PAAm / APP / APB.

[0097] Then in Example 24, THPC was applied to this promising modified recipe (PAAm / APP / 0.25 M APB + MMT) and while this combination resulted in a VTM-0 rating, is still does not compare to the best performing recipe (i.e. THPC-crosslinked PAAm / APP / 0.25M APB, Examples 16 and 17).Table 5 - UL-94 for PAAm / APP / 0.25l\ / l APB Recipe with Various AdditivesTest Results for Best Performing Recipes

[0098] The performance of the Control coating compared to the best performing recipes thus far, was evaluated using the microtorch flame test. As seen in Figure 1, with a 2.0 s flame exposure, two of the three Comparative Example B samples (column a) burned completely through, while all the best performing coacervate recipes remain intact. Although all recipes seem to have similar performance in the microtorch test, the neat PAAm / APP / APB coacervate in Example 14, 1-mil (column b) appears to be the most successful, with the backside of the sample yielding the smallest burned area. The coacervate coatings with 1% THPC in Example 16, 1-mil (column c) and 1% CaCI2 in Example 18, 1-mil (column d) topcoats exhibit similar flame performance, with the CaCI2 topcoat having a slightly darker burned area on the back. Finally, the incorporation of MMT into the PAAm / APP / 0.25M APB coacervate, followed by a 1% THPC topcoat in Example 24 (column e), results in a similar performance compared to the 1% THPC or 1% CaCI2 topcoats. However, the char formation for this coating appears to be smoother compared to the other coacervate coatings, which is likely due to the clay additive forming a ceramic char barrier, hindering the visibility of intumescent bubbling observed in the other coacervate systems.Testing for Importance of Coacervate System

[0099] To confirm the importance of active ingredients being in the coacervate phase, the flame performance of the dried coacervate and individual coacervate ingredients were evaluated as solids suspended in a solvent. A sample of PAAm / APP / APB coacervate was placed in a 70 °C oven for 48 hours to ensure the material was completely dried. The dried coacervate was then ground into a powder and added in various concentrations (30, 50, and 60 wt%) to 20 wt% polystyrene (PS) in methyl ethyl ketone (MEK). The solution was then cast onto PET via blade coating and was dried in a 70 °C oven, forcing solvent evaporation and leaving behind only dried coacervate solids and polystyrene. PAAm, APP, and APB were added as solids in the same weight ratio (7.5 wt%, 22.5 wt%, and 0.5 M, respectively) to the same PS / M EK mixture to assess the performance of the bulk ingredients compared to the ingredients in coacervate. The coating process was identical to that of the dried coacervate system and the coatings for both systems were transparent, with small particulates evenly distributed throughout. Table 6 summarizes the UL-94 flame test results for the dried coacervate and bulk coacervate ingredients coatings. The dried coacervate coating burned the length of the sample with the first flame exposure and melt dripped, leading to cotton ignition, which deems it unrated at all concentrations. Similarly, the coating containing bulk coacervate ingredients melt dripped, resulting in an unrated VTM rating. While the coacervate phase enables molecular interactions to yield a coating that results in ideal flame behavior, the solvent system requires non-active ingredients (i.e., polystyrene) that contribute to the flammability of the material. With the coacervate system, all the ingredients present in the film are actively contributing to the flame retardancy of the substrate.Table 6 UL-94 test results for dried coacervate and coacervate ingredients in PS / MEK.

[0100] Additional improvements may be undertaken by reducing the brittleness of the PAAm / APP / APB coating, which could be accomplished by reducing the total solids in the coacervate or by using a thinner bar gap to deposit less material. To further improve coating uniformity and ease of manufacturing, alternative deposition methods for the THPC crosslinker can be explored, such asblade coating. However, THPC alone is not viscous enough to effectively blade coat, so a thickening agent, such as PEO, carboxymethyl cellulose, or glass frits, must be incorporated into the THPC solution to successfully apply the topcoat.

[0101] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0102] The articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one." The phrase "and / or," as used herein in the specification and in the claims (if at all), should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0103] As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excludingany combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and / or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0104] An embodiment is an implementation or example of the present disclosure. Reference in the specification to "an embodiment," "one embodiment," "some embodiments," "one particular embodiment," or "other embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the invention. The various appearances "an embodiment," "one embodiment," "some embodiments," "one particular embodiment," or "other embodiments," or the like, are not necessarily all referring to the same embodiments.

[0105] If this specification states a component, feature, structure, or characteristic "may", "might", or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the element. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0106] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or "approximately," even if the term does not expressly appear. The phrase "about" or "approximately" may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / -0. % of the stated value (or range of values), + / -!% of the stated value (or range of values), + / -2% of the stated value (or range of values), + / -5% of the stated value (or range of values), + / ~10% of the stated value (or range of values), etc. Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0107] Additionally, any method of performing the present disclosure may occur in a sequence different than those described herein. Accordingly, no sequence of the method should be read as a limitation unless explicitly stated. It is recognizable that performing some of the steps of the method in a different order could achieve a similar result.

[0108] In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures.

[0109] In the foregoing description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.

[0110] Moreover, the description and illustration of various embodiments of the disclosure are examples and the disclosure is not limited to the exact details shown or described.

Claims

CLAIMSWe claim:

1. A composition comprising: at least one polycation between about 0.1 wt% and about 20 wt%; at least one polyanion between about 0.1 wt% and about 50 wt%; and at least one plasticizing salt between about 0.1% and about 35 wt%.

2. The composition of claim 1, wherein the at least one of polycation is polyvinylamine, polyallylamine hydrochloride and combinations of polyvinylamine, and polyallylamine hydrochloride.

3. The composition of claim 2, wherein the weight percentage of polyvinylamine and polyallylamine are equal.

4. The composition of claim 2, wherein the weight percentage of polyvinylamine is between about 0.1 wt% and about 20 wt%.

5. The composition of claim 2, wherein the weight percentage of poly(allylamine) is between about 0.1 wt% and about 20 wt%.

6. The composition of claim 1, wherein the at least one polyanion comprises ammonium polyphosphate.

7. The composition of claim 1, wherein the at least one plasticizing salt comprises ammonium pentaborate tetrahydrate.

8. The composition of claim 1, further comprising a crosslinker between about 0.1 wt% and about 4 wt%.

9. The composition of claim 8, wherein the crosslinker comprises tetrakishydroxymethyl phosphonium chloride.

10. The composition of claim 1, further comprising about 0.1 wt% to about 30 wt% boric acid.

11. The composition of claim 1, further comprising about 0.1 wt% to about 3 wt% of calcium chloride.

12. The composition of claim 1, further comprising at least about 0.1 wt% to about 15 wt% of a char promoter.

13. The composition of claim 12, wherein the char promoter is pentaerythritol.

14. A method for manufacturing a thermally resistant and flame-retardant multilayer laminate comprising: providing a polymeric or paper facestock layer; providing a polymeric adhesive layer; providing a polymeric top coat layer; depositing on the polymeric top coat layer a thermally resistant and flame-retardant composition; wherein the composition comprises: at least one polycation between about 0.1 wt% and about 20 wt%; at least one polyanion between about 0.1 wt% and about 50 wt%; and at least one plasticizing salt between about 0.1% and about 35 wt%; and sandwiching the facestock layer between the top coat layer and the adhesive layer.

15. The method of claim 14, wherein the depositing comprises spray coating.

16. The method of claim 14, wherein the at least one of polycation of the composition is polyvinylamine, polyallylamine hydrochloride, and mixtures thereof.

17. The method of claim 14, wherein the at least one polyanion of the composition comprises ammonium polyphosphate.

18. The method of claim 14, wherein the at least one plasticizing salt of the composition comprises ammonium pentaborate tetrahydrate.

19. The method of claim 14, wherein the composition further comprises a crosslinker between about 0.1 wt% and about 4 wt%.

20. The method of claim 14, wherein the composition further comprises tetrakishydroxymethyl phosphonium chloride.

21. A method for manufacturing a thermally resistant and flame-retardant multilayer laminate comprising: depositing on a polymeric top coat layer located on a polymeric or paper facestock layer, a thermally resistant and flame-retardant composition; wherein the composition comprises: at least one polycation between about 0.1 wt% and about 20 wt%; at least one polyanion between about 0.1 wt% and about 50 wt%; and at least one plasticizing salt between about 0.1% and about 35 wt%; and sandwiching the facestock layer between the top coat layer and the adhesive layer.

Images