Solution-based chemical-resistant PVDF / acrylic transparent coating film and preparation method thereof

Abstract

The present disclosure relates to a solution-based polyvinylidene fluoride (PVDF) and acrylic clear coating film and its use as a weather resistant topcoat having improved chemical resistance, for example, that can meet the chemical resistance requirements of automotive interior trim parts. The present disclosure also describes methods of making the chemically resistant clear coating films and laminates comprising the clear coating films.

Description

Technical Field

[0001] This disclosure relates to a solution-based polyvinylidene fluoride (PVDF) and acrylic transparent coating film, a method for preparing the film, and its application as a topcoat with improved chemical resistance, weather resistance, formability, and good adhesion to fluoropolymers, polyurethanes, and other polymers. This disclosure also describes a method for applying the transparent coating to a glossy paint film to meet, for example, the chemical resistance requirements of automotive interior parts. Background Technology

[0002] Decorative polymer components have become standard in the automotive industry, primarily due to the flexibility, corrosion resistance, and low cost of polymers. Polymer parts also reduce vehicle weight, which improves performance, especially fuel economy. Polymer structures with metallic finishes are now widely used as alternatives to products intended to have a chrome-plated appearance, such as car grilles, door frames, dashboards, instrument consoles, logos, emblems, badges, and other exterior and interior trim pieces.

[0003] With this shift towards polymer components, decorative films and film laminates are replacing traditional on-site painting processes for automotive body or interior parts to provide decorative surface finishes. For example, instead of spraying decorative paint onto components, decorative films can be thermoformed onto components using a three-dimensional overlay method (“TOM”) or a part overlay (“FOP”) process. Decorative paint film laminates can be thermoformed and / or injection molded into components to provide gloss, color, and weather resistance to the surface of the component. Instead of directly applying metal to a molded substrate, typically via vacuum deposition, metallized film laminates can be molded onto components to provide metallized polymer finishes and can complement and even replace bright reflective metallic surface treatments, particularly chrome plating.

[0004] Clear coating films often form part of a film laminate as a topcoat or as an outer layer of the laminate. It is desirable for the clear coating film to be substantially transparent while providing weather and chemical resistance. Depending on the application, the clear coating film may need to be formed from a polymer composition selected to provide a film that does not significantly fade, peel, crack, or chalk when exposed to the environment throughout the component's expected service life. Other desired properties such as UV resistance, toughness, scratch resistance, and abrasion resistance may also need to be met. Additionally, it is ideal that the clear coating film can be molded from a two-dimensional surface to a three-dimensional surface without undesirable loss of appearance or performance.

[0005] Certain applications of membranes and membrane laminates, such as automotive interior applications, require tolerance to chemicals present in sunscreen emulsions, such as octyl methoxycinnamate, octocrylene, avobenzone, p-aminobenzoic acid, homosalate, titanium dioxide, zinc oxide, benzophenones, benzylene derivatives, salicylates, hydroxybenzophenone, phenylbenzimidazole sulfonic acid, hydroxybenzophenone and / or other known UV filters, as well as chemicals present in insect repellents, such as N,N-diethyl-m-toluamide (DEET).

[0006] Commonly used transparent coatings are formed from alloys of fluoropolymers such as polyvinylidene fluoride (PVDF) and acrylic polymers. These transparent coating films are typically cast from a dispersion of PVDF and (meth)acrylic acid mixtures.

[0007] Larger amounts of PVDF generally improve the chemical resistance of PVDF / acrylic coatings. However, coatings containing high concentrations of dispersion-based PVDF exhibit increased haze and reduced clarity and transparency. Clear coatings for highly reflective surface finishes such as chrome plating require low haze, high clarity, and transparency. While these properties can be achieved in clear coatings prepared with low PVDF content, such as 50% by weight or less, this content compromises the coating's chemical resistance. For example, such clear coatings exhibit poor resistance to chemicals such as sunscreen emulsions and insect repellents, particularly those containing N,N-diethyl-m-toluamide (DEET).

[0008] Transparent coatings derived from solution casting are also known. For example, EP 0 285 071 A2 discloses a heat-foldable laminate for automotive body exterior panels, comprising a transparent exterior coating over a colored coating. This transparent coating comprises a thermoplastic paint system containing 50-70 wt% PVDF and 30-50 wt% acrylic resin. The PVDF and acrylic resin are dissolved in a ketone mixture and then applied to a carrier using a reverse roller coater. WO 00 / 78538 A1 discloses a multilayer decorative sheet suitable for use in vehicles, comprising a transparent coating with appearance properties suitable for automotive exteriors. This transparent coating comprises a blend preferably of 50-75 wt% PVDF and 25-50 wt% acrylic resin. This PVDF and acrylic-based transparent coating can be prepared as a solution or dispersion of PVDF in an acrylic resin solution. In the examples, a mixture of a ketone and an acetate as a co-solvent is used as the solvent for the PVDF and acrylic resin.

[0009] A disadvantage of PVDF / acrylic solutions with relatively high PVDF content in ketone solvents is that these solutions must be heated to obtain a substantially clear solution. This can cause storage and shelf-life issues. US 2010 / 310880 discloses the use of lactam solvents in PVDF / acrylic systems to obtain a clear solution at room temperature. However, lactam solvents have toxicological risks and other disadvantages.

[0010] Therefore, there is a need for a transparent coating film that has significant clarity, excellent chemical resistance, weather resistance, moldability, and good adhesion to polymers such as fluoropolymers and polyurethanes, formed from a composition that can be stored at room temperature. Summary of the Invention

[0011] The inventors of this invention have discovered a solution-based PVDF / acrylic transparent coating film that has the desired clarity and transparency, formability and weather resistance, while exhibiting improved chemical resistance.

[0012] This disclosure provides, in a first aspect, a chemically resistant transparent coating film formed from a solution of a polyvinylidene fluoride (PVDF) homopolymer and a (meth)acrylate (co)polymer in a solvent system comprising dimethyl sulfoxide and a ketone, wherein the weight ratio of the PVDF homopolymer to the (meth)acrylate (co)polymer in the transparent coating film is 58:42 or greater. In some embodiments, the weight ratio of the PVDF homopolymer to the (meth)acrylate (co)polymer in the transparent coating film is 58:42-75:25. In some embodiments, the solution further comprises a crosslinking agent capable of crosslinking the (meth)acrylate (co)polymer. In some embodiments, the ketone is selected from dimethyl ketone (acetone), diethyl ketone, methyl ethyl ketone (MEK), methyl isobutyl ketone, optionally substituted or unsubstituted cyclohexanones such as trimethylcyclohexanone (TMCHONE), cyclopentanone, and mixtures thereof. In some embodiments, the transparent coating film may comprise a UV absorber and / or a hindered amine light absorber (HALS).

[0013] This transparent coating film may have a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by GM standard test method GMW14445. This transparent coating film may have a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by Ford standard test method BI 113-08.

[0014] This disclosure also provides a membrane comprising the chemically resistant transparent coating film and one or more additional film layers. The one or more additional film layers may be metallized film layers or paint film layers. In some embodiments, the chemically resistant transparent coating film is a topcoat in the membrane. This disclosure also provides an article comprising a carrier at least partially coated with the chemically resistant transparent coating film.

[0015] In another aspect, this disclosure provides a film laminate comprising a substrate and a chemically resistant transparent coating film formed from a solution of polyvinylidene fluoride (PVDF) homopolymer and a (meth)acrylic (co)polymer in a solvent system comprising dimethyl sulfoxide and a ketone, wherein the weight ratio of the PVDF homopolymer to the (meth)acrylic (co)polymer in the transparent coating film is 58:42 or greater, and wherein the transparent coating film is applied to at least a portion of the substrate. In some embodiments, the film laminate may comprise one or more film layers disposed between the substrate and the chemically resistant transparent coating film. The one or more film layers may comprise a metallized film layer. The one or more film layers may comprise a colored paint film layer.

[0016] This disclosure, in another aspect, provides a method for preparing a chemically resistant transparent coating film. The method includes the steps of: dissolving a polyvinylidene fluoride (PVDF) homopolymer and a (meth)acrylic acid (co)polymer in a solvent system comprising dimethyl sulfoxide and a ketone to form a solution, wherein the weight ratio of the PVDF homopolymer to the (meth)acrylic acid (co)polymer in the solution is 58:42 or greater; casting the solution onto a substrate; and drying the solution to form the transparent coating film. In some embodiments, the substrate is a carrier. In some embodiments, the substrate is a paint film layer. In some embodiments, the substrate may be a metallized film layer. In one embodiment, the transparent coating film has a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by GM standard test method GMW14445. In another exemplary embodiment, the transparent coating film has a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by Ford standard test method BI 113-08. Attached Figure Description

[0017] A full understanding of the invention can be obtained from the following description of certain embodiments when the invention is read in conjunction with the accompanying drawings, wherein: Figure 1 A cross-sectional view of a glossy metallized laminate having a chemically resistant transparent coating film as a topcoat, as disclosed herein.

[0018] Figure 2 This is a cross-sectional view of a paint film laminate having a chemically resistant transparent coating film as a topcoat, as disclosed in this invention.

[0019] Figure 3 This is a schematic illustration of a process for manufacturing a coating laminate as described in this disclosure. Detailed Implementation

[0020] The following description of the preferred embodiments is merely exemplary and is in no way intended to limit the invention, its application, or its uses.

[0021] The following terms used in this document have specified definitions unless the context clearly indicates otherwise.

[0022] The singular forms “an,” “a,” and “the” used herein include plural references unless the context clearly specifies otherwise. For example, although this document refers to “an” ketone, “an” (meth)acrylic acid (co)polymer, and “an” amino moiety, combinations of each of these components (multiples) may be used in this disclosure unless the context clearly specifies otherwise.

[0023] The term "multiple / items" as used in this article refers to two or more kinds / items.

[0024] The terms “comprising” and “consisting of” as used herein are synonyms with “including” or “containing”, and are inclusive or open-ended, and do not exclude additional undescribed members, elements, or method steps. If used, the expression “consisting of” is closed and excludes all additional elements. Furthermore, the expression “substantially constitutes” excludes additional substantive elements but allows the inclusion of non-substantive elements that do not significantly alter the nature of the invention.

[0025] When any numerical range is referred to, the range should be understood to include every numerical value and / or fraction between the minimum and maximum values ​​of the range. For example, a range of "1-10" is intended to include all subranges between the minimum value of 1 and the maximum value of 10 (and including both endpoints), i.e., subranges with a minimum value equal to or greater than 1 and a maximum value equal to or less than 10. When quantities, concentrations, dimensions, and other parameters are expressed in the form of ranges, preferred ranges, upper limits, lower limits, or preferred upper and lower limits, it should be understood that any range that can be obtained by combining any upper or preferred value with any lower or preferred value is also specifically disclosed, regardless of whether the resulting range is explicitly mentioned in the context.

[0026] The terms “preferred,” “preferred,” “ideally,” and “particularly,” and their synonyms, are generally used herein to refer to embodiments of the present disclosure that may provide particular benefits in certain circumstances. However, references to one or more preferred, desired, or particular embodiments do not imply that other embodiments are unavailable and are not intended to exclude those other embodiments from the scope of the present disclosure.

[0027] Molecular weights are determined as shown based on number-average or weight-average and using gel permeation chromatography with tetrahydrofuran as solvent and polystyrene standards.

[0028] The terms “acrylate” and “acrylic” are used broadly (and interchangeably) herein and include substances prepared, for example, from one or more of acrylic acid, methacrylic acid, or any acrylate or methacrylate compound. Thus, a homopolymer, for example, consisting entirely of polymerized (meth)acrylic acid, is still an “acrylate” polymer, even though no (meth)acrylate monomer is used.

[0029] As used in this article, the term "carrier" refers to a plastic base film on which a cast coating is applied. This carrier may include polyester cast films, such as polyethylene terephthalate (PET) films, or biaxially oriented polypropylene (BOPP) films, etc.

[0030] As used in this article, “curing” and similar terms refer to a process of shaping or drying materials to form a coating on a carrier, film, base layer or substrate.

[0031] As used in this article, "dispersion" refers to a finely broken solid or liquid in a continuous liquid medium. An aqueous dispersion is a dispersion in which the continuous liquid medium is water.

[0032] In this article, the term "formable" as used for a layer means that the layer can be formed, shaped, or molded from a two-dimensional surface into a three-dimensional surface without any undesirable loss of appearance or performance.

[0033] The term "homogeneous polymer" as used in this article refers to polymers formed from a single type of monomer.

[0034] As used in this article, "insect repellent" refers to a composition that can be applied to the skin to repel insects. The composition may be in the form of an emulsion, gel, or liquid and may be applied manually or via a spray or aerosol. The composition may contain N,N-diethyl-m-toluamide (DEET) in an amount of 20-30%.

[0035] When used in the context of coatings applied to a surface or substrate, the term "on" includes both coatings applied directly or indirectly to the surface or substrate. Thus, a coating applied, for example, to a primer layer covering a substrate constitutes a coating applied to the substrate.

[0036] The term "(methyl)" used in terms such as "(meth)acrylate" and "(meth)acrylic acid" is intended to indicate that hydrogen or a methyl group can be attached to the relevant carbon atom of the monomer. For example, "(meth)acrylic acid" includes acrylic acid and methacrylic acid, as well as mixtures thereof.

[0037] Unless otherwise specified, the term "polymer" includes both homopolymers and copolymers (e.g., polymers of two or more different monomers) and oligomers. Resins and polymers are used together.

[0038] The term "solution" as used in this article refers to a homogeneous mixture of two or more substances, the relative amounts of which can be continuously varied up to the solubility limit.

[0039] Unless otherwise specified, the term "substrate" as used herein refers to a substrate on which a film (single or multiple layers) is laminated. Substrates may include, for example, acrylonitrile / butadiene / styrene copolymer (ABS), polycarbonate (PC), thermoplastic polyolefin (TPO), thermoplastic polyurethane (TPU), moldable polyester, glass fiber-thermoset composites, polyvinyl chloride (PVC), stainless steel, and aluminum.

[0040] As used herein, "sunscreen lotion" refers to a composition containing compounds that absorb, reflect, or scatter radiation in the UV range and can be applied to the skin. The sunscreen lotion may be in lotion, gel, or liquid form and may be applied manually or via spray or aerosol. The sunscreen lotion may contain octyl methoxycinnamate, octocrylene, avobenzone, para-aminobenzoic acid, homosalate, titanium dioxide, zinc oxide, benzophenones, benzylene derivatives, salicylates, oxybenzone, phenylbenzimidazole sulfonic acid, oxybenzone, and / or other known UV filters. The sunscreen lotion may be waterproof. The sunscreen lotion may have an SPF of 15, 30, 45, or 50 or be commercially available.

[0041] Unless otherwise stated, the term "UV" is intended to refer to ultraviolet light.

[0042] The “total haze value” used in this article refers to the sum of internal haze and surface haze.

[0043] Unless otherwise stated, all percentages, ratios and proportions used in this article are given on a weight basis.

[0044] This disclosure relates to a solution-based clear coating film with improved chemical resistance. It has been surprisingly discovered that this clear coating film can be achieved using a solution of polyvinylidene fluoride (PVDF) homopolymer instead of a dispersion of PVDF. By dissolving the PVDF homopolymer in a solvent system containing dimethyl sulfoxide and ketones, a larger amount of PVDF can be introduced into the solution to obtain a PVDF / acrylic clear coating that exhibits chemical resistance to chemicals such as sunscreen emulsions and insect repellents while maintaining the desired clarity. Other properties, such as formability and weather resistance, can also be retained. This clear coating can be used as a film laminate, such as a topcoat on a paint film laminate or a metallized formable laminate.

[0045] Transparent coating film

[0046] According to a first aspect, a chemically resistant transparent coating film is provided, wherein the film is based on a solution of polyvinylidene fluoride (PVDF) homopolymer and (meth)acrylic acid (co)polymer in a solvent system containing dimethyl sulfoxide and ketone, wherein the weight ratio of PVDF homopolymer to (meth)acrylic acid (co)polymer in the transparent coating film is 58:42 or greater.

[0047] It has been observed that, despite the effects of certain PVDF copolymers, such as Solef purchased from Solvay, ® 21510 / 1001 PVDF copolymer and Kynar purchased from Arkema ® SL PVDF copolymers can be dissolved in common solvents to form clear coatings, but the chemical resistance of films formed from those solutions does not meet automotive specifications. It has also been observed that although dispersed PVDF homopolymers can form clear coating films with good chemical resistance, these films have a total haze value greater than 1, which is unacceptable for some automotive applications. Any haze in the clear coating compromises the visual quality of highly reflective chrome finishes.

[0048] While larger amounts of PVDF can improve the chemical resistance of films in dispersion formulations, they can also reduce film transparency and clarity. Surprisingly, it has been found that transparent coating films based on solutions of PVDF homopolymers and (meth)acrylic (co)polymers in solvent systems containing DMSO and ketones allow for the introduction of larger amounts of PVDF into these transparent coating films, resulting in improved chemical resistance while maintaining the desired level of transparency and clarity, with very low total haze values ​​(e.g., < 0.4).

[0049] The use of solvents containing DMSO and ketones to dissolve fluoropolymers is already disclosed in US 2014 / 100313. However, what is remarkable is that this solvent, when used to dissolve PVDF homopolymers and (meth)acrylic (co)polymers in a weight ratio of 58:42 or greater, produces transparent coating films that exhibit improved chemical resistance and the desired level of transparency and clarity for use in automotive interior and exterior parts.

[0050] The PVDF homopolymer used to prepare the transparent coating film of this disclosure can be selected from PVDF homopolymers known to those skilled in the art, such as those produced by Arkema using Kynar. ® 500 Plus and Kynar ® Those 500 FSF PVDF sold by Solvay under Hylar ®Those 5000S PVDF products sold, or those sold by Gujarat Fluorochemicals under the INOFLAR5125 label. This PVDF homopolymer can have a melting point of 155°C or higher, or 155-178°C.

[0051] The PVDF homopolymer may be present in the solution in an amount of up to 15% by weight.

[0052] The (meth)acrylic (co)polymer used in this transparent coating film can be a homopolymer or copolymer or a mixture thereof. The (meth)acrylic (co)polymer can be a resin having properties that can improve certain properties of the solution or the transparent coating film formed therefrom, such as adhesion promotion, viscosity control, hardness, scratch resistance, abrasion resistance, anti-blocking properties, outstanding clarity, and crosslinking functionality. Commercially available (meth)acrylic (co)polymers include Elvacite, manufactured entirely by Mitsubishi Chemical America. ® 2041, Elvacite ® 2042, Elvacite ® 2014, Elvacite ® 2552 and BR85, as well as Acryloid A11 manufactured by Dow Chemical. This (meth)acrylic (co)polymer can also be in solution form. For example, the (meth)acrylic (co)polymer can be 30-40% by weight in solvent mixtures, such as DuPont 68070 and 68080 acrylic adhesives.

[0053] The (meth)acrylic (co)polymer may be present in the solution at a maximum of 10% by weight, such as 4-7% by weight. Higher acrylic content generally provides greater scratch resistance, but at the cost of increased brittleness and poorer chemical resistance (especially to solvents). It is desirable to include acrylics in polyvinylidene fluoride (PVDF) films, especially for metallized laminates incorporating this transparent coating, as 100% PVDF films may make the metallized laminates slightly cloudy.

[0054] The ratio of PVDF homopolymer to (meth)acrylic polymer in the chemically resistant transparent coating film disclosed herein is 58:42 or greater. In some embodiments, this ratio can be 58:42-75:25. The chemical resistance of the film begins to deteriorate at ratios below 58:42. Higher ratios may reduce other preferred properties, such as gloss, hardness, and scratch resistance.

[0055] The ketone in the transparent coating composition disclosed herein can be aliphatic, alicyclic, aromatic, or a mixture of two or more of these types of ketones. The ketone can be linear or branched aliphatic and / or alicyclic ketones and can be selected from dimethyl ketone (acetone), diethyl ketone, methyl ethyl ketone (MEK), methyl isobutyl ketone, optionally substituted or unsubstituted cyclohexanones such as trimethylcyclohexanone (TMCHONE), cyclopentanone, and mixtures thereof.

[0056] In some embodiments, the weight ratio of DMSO to ketone in the transparent coating solution can be, for example, 10:90-90:10 or 70:30-30:70. In some embodiments, the total amount of solvent in the transparent coating solution can be 80-90% by weight. In some embodiments, the total amount of DMSO and ketone in the transparent coating solution can be in the range of 70-90% by weight or 73-85% by weight.

[0057] The solvent system used for the solutions of the PVDF homopolymer and (meth)acrylic acid (co)polymers described in this disclosure can be binary, i.e., composed of DMSO and a ketone. In another embodiment, the solvent system can be ternary, containing a third solvent. In other embodiments, the solvent system can have more than three solvents. These additional solvents can include 1-methoxy-2-propanol, diethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol acetate, other ethylene glycol ethers, ethyl acetate, dimethyl glutarate, dimethyl adipate, dimethyl succinate, toluene, isopropanol, and propyl acetate.

[0058] In some implementations, the total amount of DMSO plus ketone in the solvent system can be in the range of 85-100% by weight, depending on the availability of other solvents.

[0059] In another embodiment, the transparent coating film of this disclosure may contain other optional components. These optional components may be added to a solution of PVDF homopolymer and (meth)acrylic (co)polymer.

[0060] In some embodiments, the (meth)acrylic (co)polymer contains crosslinkable functional groups such as OH, carboxyl, or NH groups. In such embodiments, the solution preferably contains a crosslinking agent having crosslinkable functional groups, such as melamine, isocyanate, blocked isocyanate, and a carbodiimide functional group capable of crosslinking (meth)acrylic (co)polymers having hydroxyl, carboxyl, or NH functional groups. Crosslinking the (meth)acrylic (co)polymer can further improve the chemical resistance, scratch resistance, and abrasion resistance of the transparent coating film. It can also improve adhesion to certain substrates where the transparent coating film is in direct contact with the substrate. For example, amino plastic resins, such as melamine resins, or blocked or unblocked polyisocyanates can be used as crosslinking agents. Suitable melamine crosslinking agents include Permuthane, available from Stahl. ® XR-9116 crosslinking agent and Cymel (purchased from Allnex) ® 303LF crosslinking agent. Suitable isocyanate and blocked isocyanate crosslinking agents include Desmodur 2489, Desmodur 2580, Desmodur BL 3272 and Desmodur BL 4265SN, all from Covestro Deutschland AG. Suitable carbodiimide crosslinking agents include Permutex XR 5577 from Stahl.

[0061] In one embodiment, the (meth)acrylic (co)polymer is an OH-functional (meth)acrylic (co)polymer and the solution contains a crosslinking agent that is reactive to the OH functional groups of the (meth)acrylic (co)polymer.

[0062] In some embodiments, the solution may also include other optional components or additives that will not adversely affect the solution or the transparent coating film formed therefrom. These optional components are typically included in the transparent coating film to improve the film's aesthetic appearance, facilitate the manufacture, processing, treatment, and application of the solution or film, and further improve specific functional properties of the solution or the film obtained therefrom. Examples of these optional components include, for instance, UV absorbers, hindered amine light stabilizers, catalysts, lubricants, surfactants, preservatives, flow control agents, thixotropic agents, antioxidants, adhesion promoters, and mixtures thereof. For example, a UV absorber, such as Tinuvin manufactured by BASF, may be included. ® 928 is added to the transparent coating film to improve its weather resistance for its intended use. If present, these optional components may be present in an amount of up to 10% by weight or up to 5% by weight of the dry film.

[0063] Those skilled in the art will understand that transparent coating films can be obtained in different colors. The formable metallized laminates described herein can be prepared in different colors by introducing appropriately dyed (i.e., colored) transparent coating films. As is known to those skilled in the art, transparent coating films can be dyed, for example, using pigments, inks, or mica, and such substances can be added as needed without excessive experimentation. If dyed, the transparent coating is preferably transparent rather than opaque.

[0064] Methods for preparing membranes

[0065] In another aspect, a method for preparing a chemically resistant transparent coating film is provided, wherein the method includes the following steps: (a) Dissolving a polyvinylidene fluoride (PVDF) homopolymer and a (meth)acrylic acid (co)polymer in a solvent system containing dimethyl sulfoxide and a ketone to form a solution, wherein the weight ratio of the PVDF homopolymer to the (meth)acrylic acid (co)polymer in the solution is 58:42 or greater; (b) Apply the solution to the substrate; and (c) Dry the solution to form the transparent coating film.

[0066] This solution can be prepared by first dissolving PVDF in DMSO and ketones under heating and stirring. This dissolution step can be carried out at a temperature sufficient to dissolve PVDF, such as 30-60°C. Once the PVDF is dissolved, (meth)acrylic acid (co)polymers and other desired optional components, such as crosslinking agents or UV absorbers, can be added while maintaining heating and stirring until all components are completely dissolved.

[0067] Alternatively, the solution can be prepared by first dissolving a (meth)acrylic (co)polymer and desired additives, such as a UV absorber, in DMSO and a ketone. This dissolution step can be carried out at a temperature of 30-60°C. PVDF can then be dissolved in the DMSO / ketone / acrylic solution with agitation at the same or slightly higher temperature, for example, in the range of 40-65°C, to completely dissolve the PVDF.

[0068] As will be understood by those skilled in the art, the order in which crosslinking agents are added will depend on the type of crosslinking agent. For example, melamine and blocked isocyanate crosslinking agents can be added in any order, even though they tend to be added last. If unblocked isocyanate or carbodiimide is used as the crosslinking agent, it is added just before casting.

[0069] Once mixed, the transparent coating solution of this disclosure can be cast onto the substrate and then dried using conventional methods.

[0070] In one embodiment, the base layer can be a carrier, such as a PET film. In some embodiments, the transparent coating solution can be cast directly onto the carrier.

[0071] In alternative embodiments, the base layer can be another film already cast onto a carrier. This cast film can comprise one or more layers. Such layers can be, for example, a clear PVF base film, a metallized film, a colored base layer of a paint film, or other layers on which a clear coating is typically applied as a topcoat. U.S. Patent Nos. 6,287,672, 6,565,955, 6,858,287, and 7,854,985 include examples of different film layers that can be disposed beneath a clear coating film. These previously cast layers may be fully cured, partially cured, or they may be uncured. As is known to those skilled in the art, film layers can be cast wet-on-wet (meaning the underlying layer is not yet dry) or wet-on-dry (meaning the underlying layer is dry) depending on the application.

[0072] In some embodiments, one or more layers may exist between the transparent coating and the substrate. For example, an adhesive layer may be present between the transparent coating and the substrate to help the chemically resistant transparent coating film adhere to the substrate. Those skilled in the art will understand that, as used herein and unless otherwise stated, the concept of one layer being disposed on top of another or "between two other layers" does not necessarily mean that these layers are adjacent (i.e., in close contact). Rather, as used herein, the concept of one layer being disposed on top of another or between two other layers is intended to describe the relative positions of the layers within the film or laminate structure. Similarly, as used herein, in describing a first layer in contact with a second layer, or "opposite to a third layer," the term "opposite to..." is intended to disclose the relative positions of the first and second layers within the film or laminate structure.

[0073] As is known to those skilled in the art, a transparent coating film can be formed by casting the transparent coating solution onto the substrate via a doctor blade coating process, a reverse roller coating process, or a slot die coating process. Slot die coating is preferred. These techniques are well known in the art and will not be discussed further herein.

[0074] Depending on the application, the solution can be cast in wet thicknesses, for example, 1-500 μm. Once dried, the thickness will be 2.5-75 μm. As is known to those skilled in the art, the casting process can be adjusted to achieve the desired dry film thickness. For example, the dry film thickness may depend on the solids content and solvent density of the wet solution. If slotdie casting is used, those skilled in the art can change the pump speed to adjust the volume of solution delivered. The linear velocity can also be adjusted. The adjustment process for achieving the desired dry thickness can be different depending on the casting process used. The desired thickness depends on the application. The transparent coating film typically has a thickness of 0.1 mil (2.5 μm) to 3.0 mil (75 μm), and more typically 0.2 mil (5 μm) to 0.6 mil (15 μm).

[0075] The transparent coating film disclosed herein may be completely aligned with the substrate at its boundary, or it may be disposed on only a portion of the substrate or on multiple separate portions of the substrate.

[0076] This transparent coating film can be formed from a two-dimensional surface into a three-dimensional surface without any undesirable loss of appearance or performance.

[0077] Once the transparent coating solution is cast onto the carrier or other film layer, the solvent can be optionally flash-evaporated, for example, at room temperature for 1-5 minutes, and then the film can be dried using any conventional drying technique. For example, the solvent can be evaporated, thus making the transparent coating solution drier but not yet cured, or a fully cross-linked coating film has not yet formed. The transparent coating solution can then be cured with the substrate. Curing is preferably carried out thermally at a temperature of 60-200°C. The thermosetting solution is preferably a solution containing the aforementioned cross-linking agent.

[0078] The preferred dryer is an oven with multiple heating zones, each operating at progressively higher temperatures. For example, an oven with 4-6 heating zones in a temperature range of 200-400°F can be used.

[0079] The carrier is stable when exposed to heat, while the transparent coating film and underlying layers (if present) dry / cur. The carrier can be removed from the film before the single or multiple layers are laminated onto the substrate.

[0080] membrane laminate

[0081] In another aspect of this disclosure, a film laminate is provided, wherein a film comprising the aforementioned chemically resistant transparent coating film is hot-pressed onto a substrate to form the film laminate. The transparent coating film is an outer layer or topcoat of the laminate. The substrate may comprise polycarbonate, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), cyclic olefin copolymer (COC), polyetherimide (PEI), polystyrene, polyimide, polypropylene (PP), polyethylene (PE), polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), acrylonitrile / butadiene / styrene copolymer (ABS), or a combination of one or more of the foregoing.

[0082] In one embodiment, the membrane may comprise a chemically resistant transparent coating membrane as described above as the sole layer.

[0083] In another embodiment, the film may comprise a multilayer structure as described above, the latter comprising a chemically resistant transparent coating film of this disclosure on one or more film layers. The one or more other film layers may, for example, comprise a transparent PVF base film, an acrylic resin, a polyurethane resin, or a polyester resin, a metallization layer, a colored base layer for a paint film, or other film layers on which a transparent coating may typically be applied as a topcoat. U.S. Patent Nos. 6,287,672, 6,565,955, 6,858,287, and 7,854,985 include examples of different film layers that may be disposed beneath the transparent coating film. In this embodiment, the transparent coating film faces outwards, opposite to the substrate, and the one or more other film layers are disposed between the transparent coating film and the substrate.

[0084] In another embodiment, the film laminate may further include a release liner peelably attached to the outer transparent coating film side of the laminate. The release liner is a removable carrier sheet—it can be removed from the transparent coating film without damaging the film. The release liner may be made of materials known to those skilled in the art.

[0085] Suitable release liner materials include polyester films, such as polyethylene terephthalate (PET), or polyolefin films, such as polypropylene (PP), or other known polymer films. PET is particularly preferred as a release carrier because PET films are extremely thermally stable and remain flat even at higher temperatures during film casting and curing. An example of a suitable release carrier is REL8752, a silicone-coated release PET film from St. Gobain. This release liner can optionally be coated with an adhesive coating or a low surface energy coating. Suitable low surface energy coatings may include, for example, those formed from polyacrylic acids, polysiloxanes, and / or fluorinated compounds.

[0086] In some embodiments, an additional layer, such as a viscous polyester, may be applied to the chemical-resistant clear coating film on a surface opposite to the one or more already cast film layers. After further processing, this additional layer can serve as a release liner that can subsequently be removed to expose the clear coating film as a topcoat.

[0087] The chemical-resistant transparent coating film disclosed herein can be introduced into a membrane laminate in a manner similar to how a conventional transparent coating is introduced into a membrane laminate, provided that the chemical-resistant transparent coating film is the topcoat of the membrane laminate.

[0088] In one embodiment, the film may be a metallized film or a formable glossy film as described in U.S. Patent Nos. 6,287,672, 6,565,955 and 6,858,287, which are incorporated herein by reference, wherein the chemically resistant transparent coating film of this disclosure is a transparent topcoat.

[0089] In another embodiment, the bright metallized formable film laminate may include a formable, weather-resistant, chemical-resistant transparent coating film as described in this disclosure, a formable transparent coating leveling layer on the weather-resistant transparent coating film, and a discontinuous indium island layer deposited on the formable leveling layer in contrast to the chemical-resistant transparent coating film.

[0090] In another embodiment, discontinuous metal island layers can be deposited on the formable base layer, and a second discontinuous metal island layer can subsequently be deposited on the first discontinuous metal island layer. The presence of multiple metal layers helps maintain optical and reflective properties when the formable laminate is stretched.

[0091] Figure 1 This is a cross-sectional view of a glossy film laminate having a chemically resistant transparent coating film according to one aspect of this disclosure. The chemically resistant transparent coating film 10 is an outer coating layer and is opposite to the substrate 14. The leveling layer 11 may comprise PVF, polyurethane, or polyester resin. A metal layer 12 is vacuum deposited onto the leveling layer 11. The adhesive layer 13 may comprise polyurethane, polyester, or acrylic resin. The chemically resistant transparent coating film 10, the leveling layer 11, the metal layer 12, and the adhesive layer 13 together form a multilayer film 15. Figure 1 In this process, a multilayer film 15 has been laminated (e.g., via heat) onto a substrate 14 to form a glossy film laminate 16. The substrate 14 may contain acrylonitrile / butadiene / styrene copolymer (ABS), polycarbonate (PC), thermoplastic polyolefin (TPO), polypropylene (PP), or polyethylene terephthalate (PET), etc.

[0092] In another embodiment, the film may be a coating film comprising one or more layers, as described in U.S. Patent No. 7,854,985, which is incorporated herein by reference, wherein the chemically resistant transparent coating film of this disclosure is a transparent topcoat. Coating film laminates, methods of forming them, and manners of applying them to substrates can be found in U.S. Patent No. 7,854,985.

[0093] Figure 2 This is a cross-sectional view of a paint film laminate having the chemically resistant transparent coating film of this disclosure. The chemically resistant transparent coating film 10 is the outer paint layer. The base coating 21 may comprise a PVDF / acrylic alloy, polyurethane, polyester, or acrylic resin. The optional adhesive layer 22 may comprise polyurethane, polyester, or acrylic resin. The chemically resistant transparent coating film 10, the base coating 21, and the optional adhesive layer 22 together form a multilayer film 18. A paint film laminate 17 is formed by laminating (e.g., via heat) a substrate 14 onto the multilayer film 18. The substrate 14 may comprise acrylonitrile / butadiene / styrene copolymer (ABS), polycarbonate (PC), thermoplastic polyolefin (TPO), polypropylene (PP), or polyethylene terephthalate (PET), etc.

[0094] Figure 3 This is a schematic illustration of a general process for manufacturing a film laminate comprising a chemically resistant transparent coating film of the present disclosure. As shown, a carrier 33 is conveyed forward by a feed roller 38 through a series of process steps. The carrier 33 preferably comprises an extruded polyester film with a high-gloss surface, which can impart high gloss to the surface on which other layers, such as a primer or adhesive, are deposited. Advantageously, the carrier 33 comprises polyethylene terephthalate (PET). The carrier 33 can be 2-4 mil thick, preferably 2 mil thick.

[0095] The carrier 33 passes through a first coating station 40 where a first coating, such as the chemically resistant transparent coating film of this disclosure, can be deposited. The carrier 33, coated with the first coating, then passes through a dryer 41. Next, a second coating is deposited at coating station 42 and dried by dryer 43. Coating stations 40 and 42 can utilize any conventional coating or casting technique, such as reverse roll coating or slot die coating. Slot die coating is preferred. A third coating can then be deposited at coating station 44 and dried by dryer 46. A primer coating can then be deposited on the third coating at coating station 48 and optionally dried by dryer 49. An adhesive coating can then be deposited at coating station 50 and dried using dryer 51. Primer coating station 48 and adhesive coating station 50 can utilize any conventional coating or casting technique, such as reverse roll coating or slot die coating. Dryers 49 and 51 can utilize any conventional drying technique.

[0096] The substrate or backing sheet 30 is conveyed forward by the feed roller 52 and laminated onto the adhesive coating surface of the film on the carrier 33. The resulting film laminate is collected by the product roller 54.

[0097] Dryers 41, 43, 46, and 49 can utilize any conventional drying technique. Preferably, these dryers are ovens with multiple heating zones, where each of the successive heating zones operates at progressively higher temperatures. Alternatively, dryer 41 can be removed from the process, allowing a second coating 42, such as a primer or adhesive, to be applied to the clear coating while it is still wet using a wet-on-wet coating technique.

[0098] The carrier 33 can then be removed from the multilayer film laminate structure to expose the chemical-resistant transparent coating topcoat layer, and the film laminate can then be thermoformed and injection molded.

[0099] The following embodiments illustrate the present invention and are not intended to limit the scope of the invention in any way. In view of this disclosure, those skilled in the art will understand that many changes can be made to the specific embodiments disclosed without departing from the scope of the invention and still yield the same or similar results.

[0100] Example

[0101] Material

[0102] The following list shows some of the raw materials and ingredients used in the following embodiments. As will be understood by those skilled in the art, alternative materials or suppliers may be used.

[0103] Acrylic Black Dispersions—Glossy Black Pigment Dispersions Custom-Made for AkzoNobel

[0104] A 40% by weight solution of A-OH functionalized methacrylic acid copolymer of acrylic resin in a solvent mixture of ethylene glycol ether acetate and other esters.

[0105] Bayhydur 302—an isocyanate crosslinking agent purchased from Covestro.

[0106] BYK-346—a polysiloxane surfactant purchased from BYK Chemie.

[0107] CYCAT ® 600—A strong acid catalyst based on dodecylbenzenesulfonic acid from Allnex

[0108] Cymel ® 303LF—Methylated monomeric melamine crosslinking agent purchased from Allnex

[0109] Cymel® 385—Methylated high-iminomelamine crosslinking agent purchased from Allnex

[0110] Cymel ® XW 3106—Alkylated high-solids melamine crosslinking agent purchased from Allnex

[0111] Desmodur ® 2802—A multifunctional carbodiimide crosslinking agent purchased from Covestro

[0112] Diethylene glycol monobutyl ether acetate (DB acetate) is a solvent commercially available from Eastman Chemical.

[0113] Dipropylene glycol monomethyl ether (DPM), methyl ethyl ketone (MEK), dimethyl phthalate (DMP) — commercially available solvents

[0114] Dimethyl sulfoxide (DMSO) — a solvent purchased from Gaylord Chemical.

[0115] DuPont 68080 — Used for Tedlar ® The liquid acrylic adhesive used for laminating the PVF film onto the substrate, a 30% by weight solution of polymethyl methacrylate in a solvent mixture (toluene and isopropanol), was purchased from DuPont.

[0116] Elvacite ® 2041—A solid, non-reactive acrylic resin based on polymethyl methacrylate (PMMA), manufactured by Mitsubishi Chemical America.

[0117] Elvacite ® 2042—A solid, non-reactive acrylic resin based on polyethyl methacrylate (PEMA), manufactured by Mitsubishi Chemical America.

[0118] Elvacite ® 4412—A solid OH-functional acrylic resin based on polymethyl methacrylate (PMMA), manufactured by Mitsubishi Chemical America.

[0119] HD-2125—A polycarbonate-based polyurethane dispersion purchased from Hauthaway.

[0120] Hylar ® 5000S—PVDF resin purchased from Solvay

[0121] Kynar® 500 — PVDF resin purchased from Arkema (the examples below use Kynar) ® 500 Plus or Kynar ® PVDF grade 500 FSF (fluorinated surfactant-free). Although some examples involve specific grades of Kynar... ® 500 and others are not involved, but Kynar of this grade ® (500 is not expected to make any difference for the purposes of this disclosure.)

[0122] Permuthane ® XR-9116—Melamine crosslinking agent purchased from Stahl

[0123] Tinuvin ® 900, Tinuvin ® 928, Tinuvin ® 1130—Hydroxyphenylbenzotriazole UV absorber, purchased from BASF

[0124] Test methods

[0125] The following procedures were used to test a number of properties of the membranes and membrane laminates prepared as described herein.

[0126] Transparency / Haze / Clarity

[0127] Transmitted haze is the percentage of transmitted light that deviates from the incident beam by an average of more than 2.5 degrees. Total haze is expressed as a percentage (%). The lower the total haze value, the higher the clarity. Generally, 0% indicates complete transparency, while greater than 30% is considered diffuse or translucent. Total haze is measured by a BYK Hazegard unit according to the standard method ASTM D1003.

[0128] Adhesion

[0129] The initial cross-cut adhesion test was conducted according to ASTM D3359 Cross-Cut Tape Test Method B. This method specifies cutting the film through a cross-cut pattern with a specified spacing, applying 3M 989 Scotch tape to the cut area, and then quickly removing the tape. The crossed areas were inspected to determine if the film had loosened or peeled off, and the area was assigned a rating. Test results were reported from 0B to 5B according to this test method. 5B is the highest rating and means no film peeling.

[0130] Heat and humidity aging

[0131] The procedures for testing thermal and humidity aging are described in Tables 11 and 12. Thermal aging was performed according to method GMW16717. Thermal and humidity aging was performed according to method GMW14729.

[0132] water bath

[0133] The water bath test involves immersing the sample in a water bath at 80°C ± 2°C for 3 hours. The requirements for the water bath test are described in Tables 11 and 12.

[0134] Color fastness

[0135] The conditions and procedures for testing color fastness are described in Tables 11 and 12.

[0136] In the automotive industry, weather resistance testing of films and laminates used in automobiles is typically conducted in Florida and Arizona because colorfastness must be guaranteed when simultaneously exposed to high temperatures and sunlight. These conditions are usually simulated in a laboratory. Colorfastness after light exposure is carefully evaluated using various analytical methods, including exposing test samples to artificial light sources under controlled irradiation and humidity conditions. Colorfastness is measured according to automotive standards SAE J2412 (e.g., for automotive interior trim components) and SAE J2527 (for exterior trim), with a small color change ΔE. These testing standards involve exposing samples to xenon arc lamps, thus simulating outdoor or indoor environmental conditions depending on the testing acceleration method used. The smaller the ΔE, the better the colorfastness. A ΔE of 3 or less is generally considered acceptable for most automotive applications.

[0137] Chemical resistance

[0138] Various samples of PVDF / acrylic films were tested to evaluate their chemical resistance. Tests included General Motors Global Engineering Standard Test Procedure GMW14445 (2016), “Sunscreen and Insect Repellent Tolerance” and Ford Laboratories Test Method BI113-08 (2015), “Sunscreen Lotion and Insect Repellent Tolerance, Method A”, chemical resistance tests, and physical measurements to determine the suitability of the films when exposed to chemicals present in sunscreen lotions and insect repellents.

[0139] Table 1 explains the test sample results evaluated according to the methods and procedures specified in the GMW14445 standard.

[0140] Table 1—GMW14445 Test Evaluation and Rating

[0141] Interpret the test sample results evaluated according to Ford BI 113-08 standard method A based on Table 2.

[0142] Table 2—Ford BI 113-08 Test Evaluation and Rating AATCC refers to the American Association of Textile Chemists and Printers.

[0143] Examples 1-13: Dissolution of PVDF

[0144] PVDF powder and solvent were added in varying proportions to 2-ounce glass vials equipped with magnetic stir bar. Kynar 500 Plus, Kynar 500 FSF, and Hylar 5000S were the PVDF grades used. The vials were placed on a hot plate and agitation and heating were initiated. Under vigorous agitation, the PVDF gradually dissolved as the temperature increased. Heating and agitation were stopped at 60°C. The solution was allowed to cool to room temperature and left overnight. The results are summarized in Tables 3 and 4 (percentages shown are by weight %).

[0145] Table 3

[0146] Table 4

[0147] In all embodiments, PVDF dissolved upon heating to form a clear solution and remained a solution upon cooling. Example 7 (without MEK) gelled overnight. All other embodiments remained a solution after 24 hours under ambient conditions. The results indicate that PVDF can be dissolved in high concentrations in various solvent systems containing DMSO and MEK.

[0148] Examples 14-18: Solution-based PVDF / acrylic transparent coating films

[0149] Prepare the PVDF / acrylic membranes of Examples 14-18 with the compositions shown in Table 5 as follows. Add DMSO and MEK to a lined paint can and begin stirring and heating. Slowly add Kynar 500 while heating and stirring. Increase the stirring speed to maintain a vortex during addition and dissolution. After Kynar 500 is completely dissolved, add Tinuvin 928, acrylic resin A, and Permutex 9116 in this order. Maintain stirring and heating until 54°C to ensure all components are completely dissolved. Filter the formulation through a 100-micron bag and allow it to stand overnight to allow bubbles to rise.

[0150] Each formulation was cast onto a 2 mil PET release carrier to form a transparent coating with a dry film thickness of 0.2–0.5 mil. The coating was dried in a vented static oven at 200°F for 2 minutes, followed by drying at 350°F for 5 minutes.

[0151] Table 5

[0152] The obtained transparent film was tested for sunscreen emulsion and insect repellent according to GM's GMW14445 and Ford's BI 113-08, Method A. The test results are summarized in Table 6.

[0153] Table 6

[0154] Examples 19-23: Solution-based PVDF / acrylic transparent coating films

[0155] PVDF / acrylic membranes of Examples 19-23 with the compositions shown in Table 7 were prepared as follows. DMSO and MEK were added to a lined paint can and stirring and heating were initiated. Elvacite 2041 and Tinuvin 928 were slowly added under heating and stirring. When Elvacite 2041 was mostly dissolved at ~40°C, Kynar 500 was slowly added. Kynar 500 dissolved rapidly at 40°C. The viscosity of the mixture increased rapidly with the addition of Kynar 500. The stirring was adjusted to maintain a vortex. The mixture was further heated to 60°C to allow Elvacite 2041 and Kynar 500 to dissolve completely. The formulation was filtered through a 100-micron bag and allowed to stand overnight to allow bubbles to rise.

[0156] Each formulation was cast onto a 2 mil PET release liner to form a transparent coating with a dry film thickness of 0.2–0.5 mil. The coating was dried in a vented static oven at 200°F for 2 minutes, followed by drying at 350°F for 5 minutes.

[0157] Table 7

[0158] The obtained transparent coating film was tested for sunscreen emulsion and insect repellent according to GM's GMW14445 and Ford's BI 113-08 Method A test procedures. The test results are summarized in Table 8.

[0159] Table 8

[0160] Examples 22 and 23 were considered acceptable. No appearance changes were observed in Example 23 after testing by GM and Ford.

[0161] Examples 24 and 25: Weather resistance of PVDF / acrylic films

[0162] Prepare a PVDF / acrylic membrane with the composition shown in Table 9 as follows. Add DMSO and MEK to a 2.5-gallon stainless steel container and begin stirring and heating. Slowly add Kynar 500 Plus while heating and stirring. Increase the stirring speed during addition and dissolution to maintain a vortex. After Kynar 500 Plus has dissolved at approximately 35-40°C, add Tinuvin 928, acrylic resin A (for Example 24) or DuPont 68080 (for Example 25), and Cymel 303 in this order. Maintain stirring and heating at 50°C to ensure complete dissolution of all components. Filter the formulation through a 100-micron bag and allow it to stand overnight to allow bubbles to rise.

[0163] Each formulation was cast as a 0.2-0.5 mil film onto a 0.95 mil Tedlar PVF film (already cast on a PET carrier) using a pilot-scale coating machine equipped with a slit die coating head and a three-zone oven. The linear speed was maintained at 3 ft / min and the oven temperatures for zones 1, 2, and 3 were set to 280°F, 360°F, and 385°F, respectively.

[0164] Table 9

[0165] The obtained transparent coating film was tested for sunscreen emulsions and insect repellents according to GM's GMW14445 and Ford's BI 113-08 Method A test procedures. Test results and total haze measurements are summarized in Table 10. Test results for comparison are included with AkzoNobel 0.5mil Fluorex transparent film cast from a 72:28 PVDF homopolymer:acrylic dispersion.

[0166] The transparent coating films of Examples 24 and 25 outperformed the comparative 0.5mil Fluorex transparent film.

[0167] Table 10

[0168] The transparent coated films of Examples 24 and 25 were then subjected to standard OEM aging and lightfastness tests. Both films passed all tests. The results of the aging and lightfastness tests are summarized in Table 11 (the transparent coated film of Example 24 with a dry film thickness of 0.23 mil on a 0.95 mil TEDLAR transparent film) and Table 12 (the transparent coated film of Example 25 with a dry film thickness of 0.21 mil on a 0.95 mil TEDLAR transparent film).

[0169] Table 11

[0170] Table 12

[0171] Examples 24 and 25 demonstrate that the transparent coating film prepared according to this disclosure not only meets the chemical resistance tests of GM and Ford, but also consistently meets the weather resistance requirements.

[0172] Examples 26 and 27: Included in Tedlar ® A chemically resistant, transparent coating serves as the topcoat on a PVF substrate. Metallized film laminate

[0173] Add DMSO and MEK to a 2.5-gallon stainless steel container and begin stirring and heating. Slowly add Hylar 5000S while heating and vigorous stirring. Increase stirring speed during addition and dissolution to maintain a vortex. After dissolving Hylar 5000S at approximately 35–40°C, add Tinuvin 928, DuPont 68080 (for Example 26) or Acrylic A (for Example 27) and Cymel 303 in sequence. Continue stirring and heating to 50°C to ensure all components are completely dissolved. Filter the formulation through a 100-micron bag and allow it to stand overnight to allow bubbles to rise.

[0174] Table 13

[0175] Each formulation was cast as a 0.2-0.5 mil topcoat film onto a 0.95 mil Tedlar PVF film on a pilot-scale coating machine equipped with a slit die coating head and a three-zone oven. The linear speed was maintained at 3 ft / min and the oven temperatures were set to 280°F / 360°F / 385°F for the first, second, and third zones, respectively.

[0176] The resulting film was then metallized on the Tedlar side with indium and tin to an optical density of 1.1–1.3. This metallized side was then coated with an adhesive and laminated onto an acrylonitrile / butadiene / styrene (ABS) or polycarbonate (PC) sheet. The clear coat side was then tested for sunscreen emulsions and insect repellents according to GM's GMW14445 and Ford's BI 113-08 Method A test procedures. Both samples showed good tolerance to both GM and Ford test solutions, achieving a rating of 1 for all tests.

[0177] Examples 28-29: Metallized films comprising a chemically resistant transparent coating as a topcoat and a polyurethane base layer laminate

[0178] To prepare the base coats for Examples 28 and 29, Tinuvin 1130 was premixed with DPM. The premix was then slowly added to HD-2125 with sufficient agitation to maintain good vortexing. The mixture was allowed to soak for at least 48 hours before use. Bayhydur 302 was then added immediately before casting the coating with sufficient agitation.

[0179] Table 14

[0180] The primer and topcoat are then cast in reverse order. First, a wet chemical-resistant clear coat solution (as shown in Table 14, depending on the example, using formulations from Example 26 or Example 27) is manually cast onto a 2 mil PET 8752 release liner from Saint Gobain. This coating is then dried in an exhaust oven at 250°F for 3 minutes, followed by drying at 350°F for 3 minutes to form a chemical-resistant clear coat film with a dry film thickness of 0.2–0.5 mil. A clear primer layer with a dry film thickness of 0.6–0.7 mil is then cast onto the corresponding clear topcoat specified in Table 14. This coating is then dried in an exhaust oven at 250°F for 3 minutes, followed by drying at 350°F for 3 minutes.

[0181] The resulting two-layer transparent film was then metallized on the undercoat side with indium and tin to an optical density of 1.1-1.3. The metallized side was then coated with an adhesive and laminated onto an acrylonitrile / butadiene / styrene (ABS) or polycarbonate (PC) sheet. The release liner was then removed, and the chemical-resistant clear coat side was tested for sunscreen emulsions and insect repellents according to GM's GMW14445 and Ford's BI 113-08 Method A test procedures. Both examples passed all tests and were rated 1.

[0182] Examples 30-31: Paint films having a chemically resistant transparent coating as a topcoat and a colored basecoat

[0183] Table 15

[0184] To prepare the colored base coat, DB acetate and DMP were added to a container and stirring was initiated. Tinuvin 900 was added with vigorous stirring. After Tinuvin 900 was completely dissolved, Kynar 500 and Elvacite 2042 were added with vigorous stirring. The temperature of the mixture increased as Kynar 500 dispersed and Elvacite 2042 dissolved. The temperature was maintained at 127°F until Kynar 500 was completely dispersed. Once completely dispersed, the acrylic black dispersion was slowly added with stirring. Stirring was continued to ensure thorough mixing.

[0185] The primer and topcoat are then cast in reverse order. First, a wet chemical-resistant clear coat solution (as shown in Table 15, depending on the example, using formulations from Example 26 or 27) is manually cast onto a 2 mil PET 8752 release liner from Saint Gobain. This coating is then dried in an exhaust oven at 250°F for 3 minutes, followed by drying at 350°F for 3 minutes to form a chemical-resistant clear coat film with a dry film thickness of 0.2–0.5 mil. A colored primer with a dry film thickness of 1.5 mil is then cast onto the corresponding clear topcoat specified in Table 15. This coating is then dried in an exhaust oven at 380°F for 4 minutes.

[0186] The release liner was then removed, and the chemical-resistant clear coat side was tested for sunscreen emulsions and insect repellents according to GM's GMW14445 and Ford's BI 113-08 Method A test procedures. Both examples passed all tests and were rated 1.

[0187] Examples 32-33: Solubility of PVDF / acrylic acid in different solvents

[0188] Kynar 500 ® FSF ® Elvacite 2041 is dissolved in a mixture of two different solvents as follows. The weight percentages and solvents used are summarized in Table 16.

[0189] Add the solvent to a lined paint container equipped with a pneumatic mixer and a digital thermometer. Slowly add Kynar 500 while stirring and heating. ® FSF ® Increase the stirring speed during feeding and dissolving to maintain the vortex. (In Kynar 500) ® FSF ® After complete dissolution / dispersion, add Elvacite 2041. Heat the mixture to 60°C and maintain at 60°C with stirring for 15 minutes to ensure Kynar 500. ® FSF ® It completely dissolves with Elvacite 2041.

[0190] Table 16

[0191] In both examples, a clear PVDF / acrylic solution was formed at 60°C. The solution of Example 32 began to gel upon cooling and completely gelled upon cooling to 28°C. The solution of Example 33 remained clear and all components remained a solution after 72 hours under ambient conditions.

[0192] Examples 34-36: Films with cross-linked transparent coatings

[0193] Prepare the transparent coating as follows.

[0194] Add DMSO and MEK to a 2.5-gallon stainless steel container and begin stirring and heating. Slowly add Kynar 500 while heating and vigorous stirring. Increase stirring speed during addition and dissolution to maintain a vortex. After Kynar 500 has dissolved at approximately 35–40°C, add Tinuvin 900 and Elvacite 4412. Continue stirring and heating to 50°C to ensure all components are completely dissolved. Then filter the formulation through a 100-micron bag and let it stand overnight to allow bubbles to rise. Add the melamine crosslinking agents (Cymel 303LF and Cymel XW3106) and CYCAT 600 to the degassed mixture with low stirring for 15 minutes, and begin coating operations after 1 hour. The weight percent of all components used is shown in Table 17.

[0195] Table 17

[0196] Two different films comprising a clear coating and a base coating were prepared: one with the clear coating of Example 34 and the other with a commercially available dispersion-based PVDF / non-reactive acrylic clear coating (Fluorex clear coating, purchased from AkzoNobel). This clear coating was cast as a 0.5 mil (DFT) topcoat on a 2 mil (50 μm) PET carrier film on a pilot-scale coater equipped with a slit die coating head and a three-zone oven. The linear speed was maintained at 3 ft / min, and the oven temperatures were set to 250°F / 320°F / 380°F for the first, second, and third zones, respectively.

[0197] A base coat was applied to the transparent coating at a dry film thickness of 1 mil and dried in a three-zone oven, where the linear speed was maintained at 3 ft / min and the oven temperatures were set at 250°F / 320°F / 320°F for the first, second, and third zones, respectively. The resulting film was then laminated onto ABS. The laminate was then thermofolded at 320°F to a flat mold and cut to prepare a test panel.

[0198] The pencil hardness (according to ISO 15184), scratch resistance (Chrysler scratch resistance LP-463DD-18-02 method A), gloss retention (20° gloss retention percentage measured using a BYK miniature triangular gloss meter after abrasion resistance testing), abrasion resistance (Chrysler abrasion resistance LP-463PB-51-01; CS-10; 500g weight, 1000 cycles), and chemical resistance to brake fluid (exposure to brake fluid at 158°F for 30 minutes; GMW14701 4.3.1.3 method 3) of each board were tested. The results are shown in Table 18.

[0199] Table 18 Maximum load without causing scratches.

[0200] Ratings range from 1 (overall structural damage) to 10 (no change). Ratings of 8 (only minor surface changes) or higher are considered acceptable.

[0201] The results showed that the film with a transparent PVDF / acrylic topcoat containing OH-functional acrylic resin and crosslinking agent (Example 35) had improved chemical resistance, scratch resistance and abrasion resistance compared to the film with a commercially available PVDF / acrylic transparent coating containing non-reactive acrylic resin (Example 36).

Claims

1. A chemically resistant transparent coating film, wherein the film is formed from a solution of polyvinylidene fluoride (PVDF) homopolymer and (meth)acrylic acid (co)polymer in a solvent system containing dimethyl sulfoxide and ketone, wherein the weight ratio of PVDF homopolymer to (meth)acrylic acid (co)polymer in the transparent coating film is 58:42 or greater.

2. The transparent coated film of claim 1, wherein the film has a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by GM standard test method GMW14445.

3. The transparent coated film of claim 1 or 2, wherein the film has a total haze value of 1 or less as measured by ASTM D1003 and a chemical resistance rating of 2 or less as measured by Ford Standard Test Method BI 113-08.

4. A transparent coating film according to any one of the preceding claims, wherein the weight ratio of PVDF homopolymer to (meth)acrylic (co)polymer in the transparent coating film is in the range of 58:42-75:

25.

5. A transparent coating film according to any one of the preceding claims, wherein the solution further comprises a crosslinking agent capable of crosslinking the (meth)acrylic (co)polymer.

6. The transparent coating film according to claim 5, wherein the (meth)acrylic (co)polymer is an OH-functional (meth)acrylic (co)polymer and the crosslinking agent is reactive to the OH functional groups of the (meth)acrylic (co)polymer.

7. A transparent coating film according to any one of the preceding claims, wherein the ketone is selected from dimethyl ketone (acetone), diethyl ketone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, substituted cyclohexanone such as trimethylcyclohexanone (TMCHONE), cyclopentanone, and mixtures thereof.

8. A transparent coating film according to any one of the preceding claims, wherein the film further comprises a UV absorber and / or a hindered amine light stabilizer (HALS).

9. A membrane comprising a chemically resistant transparent coating film according to any one of the preceding claims and one or more additional film layers.

10. The membrane of claim 9, wherein the one or more additional membrane layers comprise a metallized membrane layer or a colored varnish membrane layer.

11. An article comprising a carrier at least partially coated with a transparent coating film according to any one of claims 1-8 or the film according to claim 9 or 10.

12. A membrane laminate, comprising: Substrate; and The chemical-resistant transparent coating film according to any one of claims 1-8 or the film according to claim 9 or 10, wherein the transparent coating film or the film according to claim 9 or 10 is applied to at least a portion of the substrate.

13. A method for preparing a chemically resistant transparent coating film according to any one of claims 1-8, comprising the following steps: A solution is formed by dissolving a polyvinylidene fluoride (PVDF) homopolymer and a (meth)acrylic acid (co)polymer in a solvent system containing dimethyl sulfoxide and a ketone, wherein the weight ratio of the PVDF homopolymer to the (meth)acrylic acid (co)polymer in the solution is 58:42 or greater. The solution is then applied to the substrate. as well as The solution is dried to form the transparent coating film.

14. The method of claim 13, wherein the substrate is a carrier, a metallized film layer, or a paint film layer.

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