Acrylic films including menthyl (METH)acrylate

Abstract

Films comprising a layer formed from a film composition comprising menthyl (meth)acrylate monomer. Method of making such films and articles including the same.

Description

[0001] ACRYLIC FILMS INCLUDING MENTHYL (METH)ACRYLATE

[0002] BACKGROUND

[0003] Acrylic films are versatile materials integral to many industries. Because of their unique combination of physical properties which can include, for example, optical clarity, dimensional stability, as well as chemical, weather, and impact resistance, acrylic films may lend themselves to a broad range of uses across a variety of fields and are found in many products (e.g., bullet-resistant barriers, airplane parts, high-end furniture, backings for adhesive articles).

[0004] SUMMARY

[0005] In one aspect, provided herein are acrylic films comprising a layer formed from an acrylic film composition comprising a menthyl (meth)acrylate monomer. In another aspect, methods of making such acrylic films are disclosed. In another aspect, articles including such acrylic films are disclosed.

[0006] As used herein:

[0007] "alkyl group" and the prefix "alk-" have only C-C bonds and C-H bonds and are inclusive of both straight chain and branched chain groups and of cyclic groups. In some embodiments, alkyl groups have up to 30 carbons (in some embodiments, up to 20, 15, 12, 10, 8, 7, 6, or 5 carbons) unless otherwise specified. Cyclic groups can be monocyclic or polycyclic and, in some embodiments, have from 3 to 10 ring carbon atoms and other alkyl substituents; the term “acrylic” refers to both acrylic and methacrylic polymers, oligomers, and monomers; the term “biobased” refers to materials that are at least partly derived from materials of biological origin; the term "biobased content" refers to the amount of carbon from a renewable resource in a material as a percent of the mass of the total organic carbon in the material, as determined by ASTM D6866-10, method B and described in US 2012 / 0288692 (Broyles et al.y, the term "free of' an element means a material includes less than 1.0 wt.%, less than 0.5 wt.%, less than 0.1 wt.% or 0 wt.% of that element; the term "(meth)acryl" refers to acryl (also referred to in the art as acryloyl and acrylyl) and / or methacryl (also referred to in the art as methacryloyl and methacrylyl) the term "renewable source" refers to a natural resource that can be replenished within a 100 year time frame, either naturally or through agricultural techniques such as, for example, plants, animals, fish, bacteria, fungi, and forestry products;

[0008] Terms such as "a", "an" and "the" are not intended to refer to only a singular entity but include the general class of which a specific example may be used for illustration. The terms "a", "an", and "the" are used interchangeably with the term "at least one".

[0009] The phrase "comprises at least one" followed by a list refers to comprising any one of the items in the list and any combination of two or more items in the list. The terms “cure” refers to joining polymer chains together by covalent chemical bonds, usually via crosslinking molecules or groups, to form a network polymer. Therefore, in this disclosure the terms “cured” and “crosslinked” may be used interchangeably. A cured or crosslinked polymer is generally characterized by insolubility but may be swellable in the presence of an appropriate solvent.

[0010] All numerical ranges are inclusive of their endpoints and non-integral values between the endpoints unless otherwise stated (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0011] Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

[0012] DETAILED DESCRIPTION

[0013] Isobomyl acrylate ("IBOA") and isobomyl methacrylate ("IBOMA") are commonly used (methjacrylate monomers in acrylic films. However, commercial sources of IBOA and IBOMA are typically contaminated with camphene and isobomyl alcohol. Camphene produces a distinct, unpleasant odor and can act as a chain transfer agent, thus lowering a cured material's molecular weight and resulting in a lower degree of conversion, ultimately increasing the cured material’s volatile organic content. Additionally, IBOA is an allergen and unreacted residuals of IBOA can be found in IBOA-containing products. As such, customers purchasing such aery late-comprising products are requesting IBOA-free compositions. The present disclosure provides menthyl (methjacrylate as an IBOA and IBOMA replacement.

[0014] Polymers are traditionally, predominantly sourced from crude-oil building blocks. As awareness of implications related to heavily relying on petroleum-based materials grows, there is increasing interest in using non-petroleum sourced raw materials such as, for example, biobased raw materials. Currently, there are few polymerizable, sustainably sourced raw materials that are commercially available. Furthermore, these limited sustainably sourced raw materials often utilize fatty acids or the like as a starting material, resulting in a limited set of properties obtainable when using these monomers in polymerizable resins. In contrast, menthyl (methjacrylate obtained from biobased L-menthol can yield complementary properties to the fatty acid-based (methjacrylates.

[0015] Provided in the present disclosure are acrylic films comprising a layer formed from an acrylic film composition comprising menthyl (methjacrylate monomer. In some embodiments, the acrylic film composition comprises menthyl (methjacrylate derived from L-menthol. In some preferred embodiments the menthyl (methjacrylate is derived from biobased L-menthol. In other preferred embodiments, the acrylic film composition is free of isobomyl (methjacrylate. In some embodiments the acrylic film composition comprises 0.1 to 80 wt.% menthyl (methjacrylate monomer. In some embodiments the acrylic film composition comprises a biobased content of at least 10%, or preferably at least 20% of the total carbon content originating from monomers. In some embodiments, the acrylic film composition further comprises a monomer selected from the group consisting of a low Tg (meth)acrylate monomer, a polar (meth)acrylate monomer, and combinations thereof. In some embodiments the acrylic film composition further comprises an additive selected from the group consisting of a UV absorber, a tackifier, a radical stabilizer, a corrosion inhibitor, a polymer additive, a photoinitiator, a filler, a plasticizer, a pigment, a rheological modifier, a film former, and combinations thereof.

[0016] In some embodiments the acrylic film is a monolithic film. In some embodiments the acrylic film may be a film layer of a multilayer (film) or adhesive construction.

[0017] In some embodiments, the acrylic film further comprises other (meth)acrylate monomers in 10 to 90%, photoinitiator(s) in 0.1 to 2%, UV stabilizers in 0 to 5%, fillers in 0 to 30%, pigments in 0 to 30%, rheological additives in 0 to 10%, or a film former in 0 to 15%. In some embodiments, at least some of the (meth)acrylate monomers have been at least partially polymerized in an initial curing step wherein the initial monomers are free of menthyl (meth)acrylate. In some embodiments at least some of the (meth)acrylate monomers have been at least partially polymerized in an initial curing step wherein the initial monomers comprise menthyl (meth)acrylate.

[0018] In some embodiments, the acrylic film has a thickness of 5 to 250 pm. In some embodiments the acrylic film has a tensile strength of 1 to 50 MPa. In some embodiments the acrylic film has an E-modulus of 1 to 2000 MPa. In some embodiments the acrylic film has an elongation at break of at least 150%. In some embodiments the acrylic film has an average VOC weight loss in ppm of less than 25000.

[0019] Methods of making acrylic films of the present disclosure and articles including the same are also disclosed. In some embodiments the acrylic film may be characterized as a backing for an adhesive article such as a sheet or tape.

[0020] The “Dahlquist Criterion for Tack” is widely recognized as a necessary condition of a pressure sensitive adhesives (PSA). It states that a PSA has a shear storage modulus (G') of less than 3xl06dyne / cm2(0.3 MPa) at approximately room temperature (25° C) and a frequency of 1 hertz (Pocius, Adhesion and Adhesive Technology 3rd Ed., 2012, p. 288). A shear storage modulus can be converted to a tensile storage modulus using the following equation: E' = 2G'( r + 1 ), where r is Poisson' s ratio for the relevant material. Using this equation and given that Poisson' s ratio of elastomers and PSAs is close to 0.5, the Dahlquist Criterion expressed as a tensile storage modulus (E') is less than 0.9 MPa (9xl06dyne / cm2).

[0021] The acrylic films described herein generally have a tensile storage modulus (E') at 25 °C of greater than 9xl06dynes / cm2(0.9 MPa) or IxlO7dynes / cm2(1 MPa) at 1 hertz as can be measured by dynamic mechanical analysis (as determined by the test method described in the Examples). The tensile storage modulus (E') at 25 ° C and 1 hertz is usually greater than 5x107dynes / cm2(5 MPa), and in some embodiments at least IxlO8dynes / cm2(10 MPa), or 5xl08dynes / cm2(50 MPa). In some embodiments, the tensile storage modulus (E') at 25 °C and 1 hertz is at least IxlO9dynes / cm2, 5xl09dynes / cm2, or IxlO10dynes / cm2(i.e., 1000 MPa) at 1 hertz. Thus, the acrylic film is not a pressure sensitive adhesive in accordance with the Dahlquist criterion.

[0022] The acrylic film layer comprises polymerized units of one or more (meth)acrylate ester monomer( s) derived from an alcohol (e.g., non-tertiary) containing 1 to 14 carbon atoms and preferably an average of 4 to 12 carbon atoms.

[0023] The acrylic film comprises polymerized units of one or more low Tg (meth)acrylate monomer(s), i.e. a (meth)acrylate monomer when reacted to form a homopolymer that has a Tg no greater than 0 °C. In some embodiments, the low Tg monomer has a homopolymer Tg no greater than -5 °C., or no greater than -10 °C. The Tg of these homopolymers is often greater than or equal to -80°C., greater than or equal to -70 °C., greater than or equal to -60 °C., or greater than or equal to -50 °C. The low Tg monomer may have the formula H2C=CR'C(O)OR8wherein R' is H or methyl and R8is an alkyl with 1 to 22 carbons or a heteroalkyl with 2 to 20 carbons and 1 to 6 heteroatoms selected from oxygen or sulfur. The alkyl or heteroalkyl group can be linear, branched, cyclic, or a combination thereof.

[0024] Exemplary low Tg monomers include, but are not limited to, ethyl acrylate, n-propyl acrylate, n- butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2- methylbutyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2 -pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, octadecyl acrylate, and dodecyl acrylate.

[0025] Low Tg heteroalkyl acrylate monomers include, but are not limited to, 2-methoxyethyl acrylate and 2 -ethoxyethyl acrylate.

[0026] In some embodiments, the acrylic film comprises polymerized units of at least one low Tg monomer having an alkyl group with 6 to 20 carbon atoms. In some embodiments, the low Tg monomer has an alkyl group with 7 or 8 carbon atoms. Exemplary monomers include, but are not limited to, 2- ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isodecyl (meth)acrylate, and lauryl (meth)acrylate. In some embodiments, the monomer is an ester of (meth)acrylic acid with an alcohol derived from a renewable source, such as 2-octyl (meth)acrylate.

[0027] The acrylic fdm typically comprises at least 10, 15, 20 or 25 wt.-% of polymerized units of monofunctional alkyl (meth)acrylate low Tg monomer (i.e., having a homopolymer Tg of less than 0 °C.), based on the total weight of the polymerized units (i.e., excluding inorganic filler or other additives). As used herein, wt.-% of polymerized units refers to the wt-% based on the total weight of the (meth)acrylic polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. The acrylic film typically comprises no greater than 60, 55, 50, 45, or 40 wt.-% of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0 °C., based on the total weight of the polymerized units.

[0028] In other embodiments, the acrylic film comprises less than 10 wt.-% of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0 °C based on the total weight of the polymerized units of the (meth)acrylic polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. For example, the minimum concentration of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0 °C. may be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 wt.-%.

[0029] When the acrylic film is free of unpolymerized components such as inorganic filler and additives, the wt.-% of specified polymerized units is approximately the same as the wt.-% of such polymerized units present in the acrylic film composition. However, when the acrylic film comprises unpolymerized components, such as inorganic filler or other unpolymerizable additives the total acrylic film composition can comprise substantially less polymerized units. In general, the total amount of unpolymerizable additives may range up to 25 wt.-%. Thus, in the case of the acrylic film comprising such unpolymerizable additives the concentration of specified polymerized units can be as much as 5, 10, 15, 20, 25 wt.-% less, depending on the total concentration of such additives. For example, when the acrylic film comprises 20 wt.-% inorganic filler, the concentration of low Tg monofunctional alkyl (meth) acrylate monomer may be 20% less, i.e. at least 8 wt.-%, 12 wt.-% etc.

[0030] The acrylic film generally comprises at least one (e.g. non-polar) high Tg monomer, i.e., a (meth)acrylate monomer that when reacted to form a homopolymer has a Tg greater than 0 °C. The high Tg monomer more typically has a homopolymer Tg greater than 5 °C., 10 °C., 15 °C., 20 °C., 25 °C., 30 °C., 35 °C., or 40 °C.

[0031] In every embodiment the acrylic film comprises L- or D- menthyl (meth)acrylate or combinations thereof.

[0032] In typical embodiments, the acrylic film comprises at least one high Tg monofunctional alkyl (meth)acrylate monomer including for example, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobomyl acrylate, isobomyl methacrylate, L- and / or D- menthyl (meth)acrylate, norbomyl (meth)acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl acrylate, cyclohexyl acrylate, and propyl methacrylate or combinations thereof.

[0033] In some embodiments, the acrylic film comprises at least 1, 2, or 3 wt.-% up to 35 or 40 wt-% of polymerized units of a monofunctional alkyl (meth)acrylate monomer having a Tg greater than 40 °C., 50 °C., 60 °C., 70 °C., or 80 °C. based on the total weight of the polymerized units (i.e. excluding inorganic filler or other additives). In some embodiments, the acrylic film comprises no greater than 30, 25, 20, or 10 wt.-% of polymerized units of high Tg monofunctional alkyl (meth)acrylate monomer. Further, in some embodiments, the acrylic film comprises less than 1.0, 0.5, 0.1 wt.-% polymerized units of high Tg monofunctional alkyl (meth)acrylate monomer.

[0034] In other embodiments, the acrylic film, comprises greater than 40 wt.-% of polymerized units of a monofunctional alkyl (meth)acrylate monomer having a Tg greater than 40 °C. based on the total weight of the polymerized units of the (meth)acrylic polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. For example, the maximum concentration of polymerized units of a monofunctional alkyl (meth)acrylate monomer having a Tg greater than 40 °C. may be 50, 60, 70, 80, or 90 wt.-%. In typical embodiments, the acrylic film further comprises at least 10, 15 or 20 wt.-% and no greater than 65 wt.-% of polymerized units of polar monomers. Such polar monomers generally aid in compatibilizing the film former polyvinyl acetal (e.g. butyral) polymer with the high and low Tg alkyl (meth)acrylate solvent monomers. The polar monomers typically have a Tg greater than 0 °C., yet the Tg may be less than the high Tg monofunctional alkyl (meth)acrylate monomer.

[0035] Representative polar monomers include for example acid-functional monomers, hydroxyl functional monomers, nitrogen-containing monomers, and combinations thereof.

[0036] In some embodiments, the acrylic film comprises polymerized units of an acid functional monomer (a subset of high Tg monomers), where the acid functional group may be an acid per se, such as a carboxylic acid, or a portion may be salt thereof, such as an alkali metal carboxylate. Useful acid functional monomers include, but are not limited to, those selected from ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated phosphonic acids, and mixtures thereof. Examples of such compounds include those selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, citraconic acid, maleic acid, oleic acid, 3 -carboxy ethyl (meth)acrylate, 2- sulfoethyl methacrylate, styrene sulfonic acid, 2-acrylamido-2 -methylpropanesulfonic acid, vinylphosphonic acid, and mixtures thereof.

[0037] In some embodiments, the acrylic film comprises 0.5 up to 20 or 25 wt.-% of polymerized units of acid functional monomers, such as acrylic acid. In some embodiments, the acrylic film comprises at least 1, 2, 3, 4, or 5 wt.-% of polymerized units of acid-functional monomers. In other embodiments, the acrylic film comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of acid-functional monomers.

[0038] In some embodiments, the acrylic film comprises polymerized units of a non-acid-functional polar monomer.

[0039] One class of non-acid-functional polar monomers includes nitrogen-containing monomers. Representative examples include N-vinylpyrrolidone; N-vinylcaprolactam; acrylamide; mono- or di-N- alkyl substituted acrylamide; t-butyl acrylamide; dimethylaminoethyl acrylamide; and N-octyl acrylamide.

[0040] In some embodiments, the acrylic film comprises at least 0.5, 1, 2, 3, 4, or 5 wt.-% of polymerized units of nitrogen-containing monomers and typically no greater than 25 or 30 wt.-%. In other embodiments, the acrylic film comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of nitrogencontaining monomers.

[0041] Another class of non-acid-functional polar monomers includes alkoxy -functional (meth)acrylate monomers. Representative examples 2-(2 -ethoxy ethoxy)ethyl (meth)acrylate, 2 -ethoxy ethyl (meth)acrylate, 2-hydroxyethyl (meth) acrylate, 2-(methoxyethoxy)ethyl, 2 -methoxy ethyl methacrylate, 3- hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and polyethylene glycol mono(meth)acrylates.

[0042] In some embodiments, the acrylic film comprises at least 0.5, 1, 2, 3, 4, or 5 wt.-% of polymerized units of alkoxy -functional (meth)acrylate monomers and typically no greater than 30 or 35 wt-%. In other embodiments, the acrylic film comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of alkoxy -functional (meth)acrylate monomers.

[0043] Preferred polar monomers include acrylic acid, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate; N,N-dimethyl acrylamide and N-vinylpyrrolidinone. The acrylic film generally comprises polymerized units of polar monomer in an amount of at least 10, 15 or 20 wt.-% and typically no greater than 65, 60, 55, 50 or 45 wt.-%.

[0044] The acrylic film may optionally comprise polymerized units of vinyl monomers including vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrene (e.g., alpha-methyl styrene), vinyl halide, and mixtures thereof. As used herein vinyl monomers are exclusive of polar monomers. In some embodiments, the acrylic film comprises at least 0.5, 1, 2, 3, 4, or 5 wt.-% and typically no greater than 10 wt.-% of polymerized units of vinyl monomers. In other embodiments, the acrylic film comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of vinyl monomers.

[0045] In some favored embodiments, the polymerized units of the (meth)acrylic polymer contain aliphatic groups and lack aromatic moieties.

[0046] In typical embodiments, the monomer(s) are polymerized to form a statistical (meth)acrylic copolymer.

[0047] In typical embodiments the acrylic film comprises a polyvinyl acetal polymer as film former as described in greater detail in PCT / IJS2015 / 64215, filed Dec. 7, 2015. The polyvinyl acetal polymer is typically a random copolymer. However, block copolymer and tapered block copolymer may provide similar benefits as random copolymers.

[0048] The content of polyvinyl acetal (e.g. butyral) typically ranges from 65 wt.-% up to 90 wt.-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl acetal (e.g. butyral) ranges from about 70 or 75 up to 80 or 85 wt.-%. The content of polyvinyl alcohol typically ranges from about 10 to 30 wt-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl alcohol of the polyvinyl acetal (e.g. butyral) polymer ranges from about 15 to 25 wt.-%. The content of polyvinyl acetate of the polyvinyl acetal (e.g. butyral) polymer can be zero or range from 1 to 8 wt.-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl acetate ranges from about 1 to 5 wt.-%.

[0049] In some embodiments, the alkyl residue of aldehyde comprises 1 to 7 carbon atoms. In other embodiments, the alkyl reside of the aldehyde comprises 3 to 7 carbon atoms such as in the case of butylaldehyde (Rl=3), hexylaldehyde (Rl=5), n-octylaldehyde (Rl=7). Of these butylaldehyde, also known as butanal is most commonly utilized. Polyvinyl butyral ("PVB") polymer is commercially available from Kuraray under the trade designation "MowitalTM" and Solutia under the trade designation "ButvarTM".

[0050] In some embodiments, the polyvinyl acetal (e.g. butyral) polymer has a Tg ranging from about 60 °C. up to about 75 °C. or 80 °C. In some embodiments, the Tg of the polyvinyl acetal (e.g. butyral) polymer is at least 65 or 70 °C. When other aldehydes, such as n-octyl aldehyde, are used in the preparation of the polyvinyl acetal polymer, the Tg may be less than 65 °C. or 60 °C. The Tg of the polyvinyl acetal polymer is typically at least 35, 40 or 45 °C. When the polyvinyl acetal polymer has a Tg of less than 60 °C., higher concentrations of high Tg monomers may be employed in the acrylic film composition in comparison to those utilizing polyvinyl butyral polymer. When other aldehydes, such as acetaldehyde, are used in the preparation of the polyvinyl acetal polymer, the Tg may be greater than 75 °C. or 80 °C. When the polyvinyl acetal polymer has a Tg of greater than 70 °C., higher concentrations of low Tg monomers may be employed in acrylic film composition in comparison to those utilizing polyvinyl butyral polymer.

[0051] In some embodiments, the polyvinyl acetal (e.g. PVB) polymer typically has an average molecular weight (Mw) of at least 10,000 g / mole or 15,000 g / mole and no greater than 150,000 g / mole or 100,000 g / mole. In some favored embodiments, the polyacetal (e.g. PVB) polymer has an average molecular weight (Mw) of at least 20,000 g / mole; 25,000; 30,000, 35,000 g / mole and typically no greater than 75,000 g / mole.

[0052] In some embodiments, the acrylic film comprises 5 to 30 wt-% of polyvinyl acetal polymer such as polyvinyl butyral based on the total weight of the polymerized units of the (meth)acrylate polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. In some embodiments, the acrylic film comprises at least 10, 11, 12, 13, 14, or 15 wt-% of polyvinyl acetal (e.g. PVB) polymer. In some embodiments, the acrylic film comprises no greater than 25 or 20 wt.-% of polyvinyl acetal (e.g. PVB) polymer. When the acrylic fdm comprises a polyvinyl acetal (e.g. PVB) polymer having an average molecular weight (Mw) of less than 50,000 g / mole, the acrylic film may comprise higher concentration polyvinyl acetal (e.g. PVB) polymer such as 35 or 40 wt-%. Thus, the acrylic film and composition comprises a minor amount of polyvinyl acetal (e.g. PVB) resin in combination with a major amount of (methjacrylic polymer. The amount of (methjacrylic polymer is typically at least 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 wt-% of the acrylic film.

[0053] In other embodiments, the acrylic film comprises less than 5 wt-% of polyvinyl acetal (e.g. butyral) polymer based on the total weight of the polymerized units of the (meth) acrylic polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. For example, the minimum concentration of polyvinyl acetal (e.g. butyral) polymer may be 0.5, 1, 1.5, 2, 1.5, 3, 3.5, 4, or 4.5 wt-%.

[0054] In some embodiments the acrylic film composition comprises a biobased content of at least 3, 5, 8, 10, 20, or 30% of the total carbon content originating from monomers.

[0055] In some embodiments, the acrylic film comprises polymerized crosslinker units. In some embodiments, the crosslinker is a multifunctional crosslinker capable of crosslinking polymerized units of the (methjacrylic polymer such as in the case of crosslinkers comprising functional groups selected from (methjacrylate, vinyl, and alkenyl (e.g. C3-C20 olefin groups); as well as chlorinated triazine crosslinking compounds.

[0056] Examples of useful (e.g. aliphatic) multifunctional (methjacrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as 1,6- hexanediol di(meth)acrylate, polyethylene glycol) di(meth)acrylate, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylate, and propoxylated glycerin tri(meth)acrylate, and mixtures thereof. In one embodiment, the crosslinking monomer comprises a (meth)acrylate group and an olefin group. The olefin group comprises at least one hydrocarbon unsaturation.

[0057] Dihydrocyclopentadienyl acrylate is one example of this class of crosslinking monomer. Other crosslinking monomers of this type comprising a C6-C20 olefin are described in WO2014 / 172185.

[0058] In other embodiments, the crosslinking monomer comprises at least two terminal groups selected from allyl, methallyl, or combinations thereof. An allyl group has the structural formula H2C=CH-CH2-. It consists of a methylene bridge (-CH2-) attached to a vinyl group (- CH=CH2). Similarly, a methallyl group is a substituent with the structural formula H2C=C(CH3) — CH2- — . The terminology (meth)allyl includes both allyl and methallyl groups. Crosslinking monomers of this types are described in PCT Publication WO 2015 / 157350.

[0059] In some embodiments, the acrylic film may comprise a multifunctional crosslinker comprising vinyl groups, such as in the case of 1,3-divinyl tetramethyl disiloxane.

[0060] In other embodiments, the crosslinker comprises hydroxyl-reactive groups, such as isocyanate groups, capable of crosslinking alkoxy group of the (meth)acrylic polymer (e.g. 2-hydroxyethyl acrylate (HEA)) or polyvinyl alcohol groups of the polyvinyl acetal (PVB). Examples of useful (e.g. aliphatic) multifunctional isocyanate crosslinkers include hexamethylene diisocyanate, isophorone diisocyanate, as well as derivatives and prepolymers thereof. In preferred embodiments urethane diacrylates CN965 (supplied by Sartomer) or SUA5387 (supplied by Soltech Ltd. Korea) are used. Various combinations of two or more of crosslinkers may be employed.

[0061] When present, the crosslinker is typically present in an amount of at least 0.5, 1.0, 1.5, or 2 wt.-% ranging up to 5 or 10 wt.-% based on the total weight of the polymerized units of the (meth)acrylate polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker. Thus, the acrylic film comprises such amount of polymerized crosslinker units. In some embodiments, multifunctional (meth)acrylate crosslinkers are present in an amount less than 1 wt.-%.

[0062] In other embodiments, the acrylic film comprises greater than 10 wt.-% of polymerized crosslinker units based on the total weight of the polymerized units of the (meth) acrylic polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. For example, the maximum concentration of polymerized crosslinker units may range up to 50, 55, 60, 65, 70, 75 or 80 wt.-%.

[0063] The acrylic film can be polymerized by various techniques, yet is preferably polymerized by solventless radiation polymerization, including processes using electron beam, gamma, and especially ultraviolet light radiation. In this (e.g. ultraviolet light radiation) embodiment, generally little or no methacrylate monomers are utilized. Thus, the acrylic film comprises zero or no greater than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 wt-% of polymerized units of monomer having a methacrylate group. One method of preparing the acrylic film described herein comprises dissolving the polyvinyl acetal (e.g. PVB) polymer in the unpolymerized solvent monomer(s) of the (meth)acrylic polymer forming a coatable composition of sufficient viscosity. Another method includes partially polymerizing the solvent monomer(s) to produce a syrup composition comprising a solute (meth)acrylic polymer dissolved in unpolymerized solvent monomer(s).

[0064] The viscosity of the coatable composition is typically at least 1,000 or 2,000 cps ranging up to 100,000 cps at 25 °C. In some embodiments, the viscosity is no greater than 75,000; 50,000, or 25,000 cps. The coatable composition is coated on a suitable substrate such as a release liner and polymerized by exposure to radiation.

[0065] The polymerization is preferably conducted in the absence of unpolymerizable organic solvents such as ethyl acetate, toluene and tetrahydrofuran, which are non-reactive with the functional groups of the solvent monomer and polyvinyl (e.g. PVB) acetal. Solvents influence the rate of incorporation of different monomers in the polymer chain and generally lead to lower molecular weights as the polymers gel or precipitate from solution. Thus, the acrylic film composition can be free of unpolymerizable organic solvent.

[0066] The composition may include, alone or in combination with other free-radical initiator(s), at least one photoinitiator that is activated by light, generally using an ultraviolet (UV) lamp, although other light sources such as LED lamps, Xe flashlamps, and lasers can also be used with the appropriate choice of photoinitiator.

[0067] Useful photoinitiators include those known as useful for photocuring free -radically polyfunctional (meth)acrylates. Examples of suitable photoinitiators include benzoin and its derivatives such as alphamethylbenzoin; alpha-phenylbenzoin; alpha-allylbenzoin; alpha benzylbenzoin; benzoin ethers such as benzyl dimethyl ketal (e.g., available as OMNIRAD BDK from IGM Resins USA Inc., St. Charles, Illinois), benzoin methyl ether, benzoin ethyl ether, benzoin n-butyl ether; acetophenone and its photoinitiator. Examples of suitable photoinitiators include those available under the trade designations OMNIRAD from IGM Resins (Waahvijk, The Netherlands) and include 1 -hydroxy cyclohexyl phenyl ketone (OMNIRAD 184), 2,2-dimethoxy-l,2-diphenylethan-l-one (OMNIRAD 651), bis(2,4,6- trimethylbenzoyl)phenylphosphineoxide (OMNIRAD 819), LUCIRIN TPO orLUCIRIN TPO-L, l-[4-(2- hy dro xy etho xy)phenyl] -2 -hydroxy -2 -methy 1-1 -propane- 1 -one (OMNIRAD 2959), 2-benzyl-2- dimethylamino-l-(4-morpholinophenyl)butanone (OMNIRAD 369), 2-methyl-l-[4-(methylthio)phenyl]-2- morpholinopropan-l-one (OMNIRAD 907), and 2 -hydroxy -2 -methyl- 1 -phenyl propan- 1 -one (OMNIRAD 1173), oligo[2 -hydroxy -2 -methyl-l-[4- (1 -methy lvinyl)phenyl]propanone] obtained from IGM Resins under the trade designation ESACURE KIP 150, and difunctional alpha-hydroxy ketones obtained from IGM Resins under the trade designations ESACURE ONE and ESACURE KIP 160 (2-hydroxy-l-[4-[4-(2- hydroxy-2-methylpropionyl)phenoxy]phenyl]-2-methylpropanone). A difunctional alpha-hydroxy ketone means that the photoinitiator includes two alpha-hydroxy ketone groups. A multifunctional alpha-hydroxy ketone means that the photoinitiator includes two or more alpha-hydroxy ketone groups. Additional suitable photoinitiators include benzyl dimethyl ketal, 2-methyl-2 -hydroxypropiophenone, benzoin methyl ether, benzoin isopropyl ether, anisoin methyl ether, aromatic sulfonyl chlorides, photoactive oximes, and combinations thereof. Further suitable photoinitiators include mono-ethylenically unsaturated aromatic ketones. Examples of such photoinitiators include multifunctional benzophenones (e.g., aciyloyloxybenzophenone (ABP), para-acryloyloxyethoxybenzophenone (AEBP), para-N-(methylaciyloxyethyl)- caibamoylethoxybenzophenone, 4-acryloyiox diethoxy -4-chlorobenzophenone) and acetophenones (e.g., para-acryloylox acetophenone and ortho-acrylamidoacetophenone.) Still further suitable photoinitiators include triazines such as 2,4,-bis(trichloromethyl)-6-(4-methoxyphenyl)-triazine, triazines described in U.S. 4,330,590 (Vesley), and 2,4-bis(trichloromethyl)-6-naphthenyl-s-triazine and 2,4-bis(trichloromethyl)-6-(4- methoxy)naphthenyl-s-triazine, described in U.S. 4,329,384 (Vesley)).

[0068] Such photoinitiators are typically present in an amount from 0.1 to 1.0 wt.-%. Relatively thick coatings can be achieved when the extinction coefficient of the photoinitiator is low.

[0069] The acrylic film of the present disclosure may include other components useful, for example, in sealant and adhesive compositions. For example, the composition can include at least one of toughening agents (e.g., acrylic core / shell polymers; styrene-butadiene / methacrylate core / shell polymers; acrylonitrilebutadiene mbber), plasticizers (e.g., aliphatic and aromatic hydrocarbons, alkyl esters, alkyl ethers, aryl esters, and aryl ethers), tackifiers, corrosion inhibitors, UV stabilizers, antioxidants, free radical inhibitors, flame retardants, thixotropic agents such as fumed silica, dyes, pigments (e.g., ferric oxide, brick dust, carbon black, and titanium oxide), reinforcing agents (e.g., silica, magnesium sulfate, calcium sulfate, and beryllium aluminum silicate), clays such as bentonite, other suitable filler (e.g., glass beads, talc, and calcium metasilicate), dispersing agents, wetting agents, adhesion promoters (e.g., silane coupling agents), antistatic agents, thermally and / or electrically conductive particles, foaming agents, and hollow polymeric or ceramic microspheres (e.g., glass bubbles). In some embodiments, the composition of the present disclosure includes a filler. Further examples of fillers useful for some embodiments of the composition of the present disclosure include at least one of a micro-fibrillated polyethylene, a fumed silica, a talc, a wollastonite, an aluminosilicate clay (e.g., halloysite), phlogopite mica, calcium carbonate, kaolin clay, metal oxides (e.g., barium oxide, calcium oxide, magnesium oxide, zirconium oxide, titanium oxide, zinc oxide), nanoparticle fillers (e.g., nanosilica, nanozirconia).

[0070] Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure. EXAMPLES

[0071] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. The following abbreviations are used in the Examples section: wt.%=weight percentage, mg=milligrams, g=grams, ppm=parts per million, pm=micrometers, mm=millimeters, cm=centimeters, mJ / =millijoules, MPa=megapascals, K=Kelvin, °C=degrees Celsius, Hz=hertz, N=Newtons, in=inches, h=hour(s), VOC=volatile organic compound, Tg=glass transition temperature, PSA=pressure-sensitive adhesive, DMA=dynamic mechanical analysis, DSC=differential scanning calorimetry, RPM=rounds per minute.

[0072] Materials Used in Examples

[0073] Synthesis of L-menthyl acrylate ("L-MTA"):

[0074] All quantities were calculated relative to the amount of L-menthol. To a 1 L round bottom flask was added L-menthol (500 g, 3.20 mol, 1.00 eq.), acrylic acid (277 g, 3.84 mol, 1.20 eq.), phenothiazine (1.00 g, 2000 ppm), furfural (1.00 g, 2000 ppm), p-toluenesulfonic acid (pTSA, 5.75 g, 1.15 wt%), and cyclohexane (75.0 g, 15.0 wt%). The flask was equipped with a 30 cm Vigreux column and a Dean-Stark head that was filled with cyclohexane containing 50 ppm of furfural. The separated water was collected every 30 min to Ih throughout the complete reaction. First, the mixture was heated to 120 °C and reacted for Ih, where tO is marked by the start of reflux from the Dean-Stark head. Next, the setpoint was increased to 140 °C, and the mixture was allowed to react for 5.5 h. Finally, the mixture temperature was increased to 150 °C for another 2.5 h, after which the mixture was cooled to room temperature. The conversion was determined via 1H-NMR and was found to be typically >98%.

[0075] The Dean-Stark head was replaced with a Claisen head and a distilling condenser. Vacuum was applied and the crude was heated to 80 °C for Ih. An ultimate vacuum of 5 mmHg was obtained. Next, the batch was heated from 115 °C to 135 °C to collect 545 g of the desired product (95-97°C at 5 mmHg), to which 10 mg of MEHQ (18 ppm) was added. A clear change in refractive index compared to lower boiling compounds can be observed when L-MTA is being distilled. The purity was determined to be >98 wt% via 1H-NMR.

[0076] Two batches of distilled L-MTA (545 g and 550 g) were combined and washed with 220 g of a 2% aqueous sodium hydroxide solution. The organic phase was then washed with 220 g of deionized water until the aqueous phase was neutral (three times). The obtained slightly turbid organic phase was finally filtered over a filter paper to obtain clear L-MTA (1083 g, 80.1% yield). The purity was determined to be >98 wt% via 1H-NMR and GC. 19 mg of MEHQ was added (18 ppm expected). Via standard QC tests, the presence of 19 ppm MEHQ, 0.3 ppm phenothiazine, and 0.173% water was determined. No residual furfural was detected in the sample.

[0077] Synthesis of DL-menthyl acrylate ("DL-MTA")

[0078] All quantities were calculated relative to the amount of DL-menthol. To a 1 L round bottom flask was added DL-menthol (500 g, 3.20 mol, 1.00 eq.), acrylic acid (277 g, 3.84 mol, 1.20 eq.), phenothiazine (1.00 g, 2000 ppm), furfural (1.00 g, 2000 ppm), p-toluenesulfonic acid (pTSA, 5.75 g, 1.15 wt%), and cyclohexane (75.0 g, 15.0 wt%). The flask was equipped with a 30 cm Vigreux column and a Dean-Stark head that was filled with cyclohexane containing 50 ppm of furfural. The separated water was collected every 30min to Ih throughout the complete reaction. First, the mixture was heated to 120 °C and reacted for Ih, where tO is marked by the start of reflux from the Dean-Stark head. Next, the setpoint was increased to 140 °C, and the mixture was allowed to react for 5.5 h. Finally, the temperature was increased to 150 °C for another 2.5 h, after which the mixture was cooled to room temperature. The conversion was determined via 1H-NMR and was found to be >98%.

[0079] The Dean-Stark head was replaced with a Claisen head and a distilling condenser. Vacuum was applied and the crude was heated to 80 °C for Ih. An ultimate vacuum of 5 mmHg was obtained. Next, the batch was heated from 115 °C to 135 °C to collect 5425 g of the desired product (95-97 °C at 5 mmHg), to which 10 mg of MEHQ (18 ppm) was added. A clear change in refractive index compared to lower boiling compounds can be observed when DL-MTA is being distilled. The purity was determined to be >98 wt% via 1H-NMR.

[0080] Two batches of distilled DL-MTA (both 542 g) were combined and washed with 220 g of a 2% aqueous sodium hydroxide solution. The organic phase was then washed with 220 g of deionized water until the aqueous phase was neutral (three times). The obtained slightly turbid organic phase was finally filtered over a filter paper to obtain clear DL-MTA (1076 g, 80.0% yield). The purity was determined to be 98.7 wt% via 1H-NMR. 20 mg of MEHQ was added (19 ppm expected). Via standard QC tests, the presence of 21 ppm MEHQ, 0.2 ppm phenothiazine, and 0.160% water was determined. No residual furfural was detected in the sample.

[0081] Example 1 : Acrylic Films Including Stericallv Encumbered Monomers

[0082] Acrylic Film Formulation Preparation: Formulations were prepared by combining all components listed in Table 1 into a polypropylene mixing cup (from FlackTek, Inc., Landrum, SC). The cup was closed with a polypropylene lid and the mixture was high shear mixed at ambient temperature and pressure using a SPEEDMIXER (Hauschild SpeedMixer inc., Dallas Texas) for at least 30 s at 2000 revolutions per minute (rpm).

[0083] AC475 Photocured Acrylic Film Preparation: On a glass slide was placed a release liner (release side up) and a 15-mil rubber spacer with an approximately 20 mm x 6 mm rectangular cutout. The formulation was placed in the unfilled rectangle, filling the area. A second release liner was placed over the formulation slowly so as to not create any air bubbles (release side down). A second glass slide was placed over the release liner. Two clamps were placed over the glass slides in such a way that they secure the assembly but did not block the light from irradiating the material. Subsequently, the setup was irradiated using the Omnicure AC475 (Poly Dispensing Systems, Orgeval, Ile-de-France, France) 365 nm light at 25% power from a height of two inches for 120 seconds. When the glass and release liners were removed, a cured film was provided.

[0084] Dynamic Mechanical Analysis ("DMA") Test Method Temperature Ramp (for formulations CE1-1, EXI, and CE1-2): The thickness of each acrylic film was measured. The films were mounted in the tensile grips of an DMA850 (TA Instruments, New Castle, DE, USA) with an initial grip separation of 12-16 mm. The measurement procedure was done to determine the precise grip separation with an initial / preload force of 0.1 N with a “Use Force Track” set to 150%. The samples were then tested at an oscillation of 0.2% strain and 1 Hz throughout a temperature ramp from at least -20 °C to 60 °C at a rate of 3 °C per minute. The temperatures at which the tan delta signal reached a maximum were recorded as the glass transition temperatures (Tg).

[0085] The film formulations and their respective films for DMA were prepared and evaluated according to the procedures above. Testing results are shown in Table 2.

[0086] Table 1. Acrylic Film Formulations

[0087] Table 2. Acrylic Film Characteristics As shown in Table 2, film formulations including L-MTA have similar mechanical properties to IBOA-comprising formulations. Ml 130, an alternative sterically encumbered monomer, yields material with a lower storage modulus and Tg.

[0088] Example 2, Acrylic Films

[0089] Test Methods

[0090] Test Method 1: Tensile Elongation Analysis

[0091] Tensile and elongation testing was performed at ambient temperature using a Tensile Tester (tensile tester from Zwick, Germany), with a 500 N loadcell. Specimens were cut (width: lin, length: 15cm) and were loaded into the grips at a distance of Lo=10 cm. Crosshead speed (strain rate) was 300 mm / min, loading the specimen to failure. Stress at break was recorded in units of megapascals (MPa) and elongation at break was determined. Sample size for each acrylic film was 5 (n = 5). The average of five measurements is given as result.

[0092] Test Method 2: Gravimetric Determination of VOCs

[0093] A 15cm x 15cm aluminum backing sheet was prepared and the weight was measured. Gloves were used to prevent contamination. Then, 10cm x 10cm samples of the acrylic film were cut out and applied onto the aluminum backing. A PSA hand-roller was used to prevent air bubbles. Subsequently, the liner material was removed, and the weight was measured again. The test samples were placed into an oven with recirculating air at 120 °C for 2h. Afterwards, weight was measured again after 20 min reconditioning at room temperature. The average VOC weight loss in ppm of the acrylic film was determined (sample size n = 2).

[0094] Test Method 3 : Determination of Tevia DMA

[0095] The samples were cut to a width of 5.3 - 5.5mm and a length of 10mm. Those specimens were then clamped and subsequently exposed to temperature ramps from -30 °C to 150 °C and a heating rate of 2K / min using a DMA 850 from TA Instruments, USA. At a constant frequency of 1Hz an oscillatory tensile amplitude of 10pm was applied, which corresponds to a strain of 0.1% at a target sample length of 10mm. The glass transition temperature was determined at the peak value of the obtained loss tangent maxima. Two measurements per sample were conducted and the average glass transition temperature Tg was determined (sample size n = 2).

[0096] Test Method 4: Determination of T?via DSC

[0097] The samples were cut to small specimens with approx. 5mg of weight each. Each specimen was then put into a standard alumina pan with holes in the lid. A DSC Q2000 from TA Instruments, USA with autosampler was used. The sample head was flushed with nitrogen gas. After calibration with indium, specimens were tested using the following temperature cycle:

[0098] 1) Equilibrate at 150 °C; 2) cooling down to -50 °C at 20 °C / min; 3) isothermal for 5 min; 4) Ramp to 150 °C at 5°C / min. The glass transition temperature was determined in segment 4) using the method of halfheight. Two measurements per sample were conducted and the average glass transition temperature Tg was determined (sample size n = 2).

[0099] Samples

[0100] Preparation of 50% CN965 in IBOA or L-MTA: A mixture of 50 wt.% CN965 and 50 wt.% of IBOA or L-MTA was prepared by weighing in both compounds and rolling at 35 RPM using a LABINCO LD209750 Rolling Bench jar roller (available from LABINCO, Breda, Netherlands).

[0101] Preparation of acrylic film formulations: Composition formulations are provided in Table . All components were added to ajar with 4-HBA and AA being added last. B60H may be dissolved more quickly by first dispensing in hydrophobic monomers and then dissolving in more hydrophilic monomers. Rolling (35RPM, 2 days) was performed using a LABINCO LD209750 Rolling Bench jar roller (available from LABINCO, Breda, Netherlands).

[0102] Coating of acrylic film formulations: Acrylic film formulations were coated using a notch bar setup. A closed face approach was used, coating in between two PET liners (75pm thickness each). The notch bars were set to provide acrylic films with a thickness of 90pm.

[0103] Polymerization of acrylic film formulations: The photopolymerization was carried out using 365nm from both sides and a dose of 9000 mJ / cm2.

[0104] Table 3. Acrylic Film Formulations Table 4. Characterization of Acrylic Films

[0105] As demonstrated by the data in Table 4, similar tensile properties may be achieved by replacing IBOA with L-MTA. As shown in Table 4, tensile strength and modulus with IBOA-containing formulations was slightly higher than their respective L-MTA-containing counterparts. Elongation was higher with L-MTA-containing formulations and may be attributed to differences in the glass transition temperatures of the respective homopolymers of IBOA and L-MTA, impacting glass transition temperatures of the respective acrylic films. The level of VOCs are similar in acrylic films comprising either IBOA or L-MTA.

[0106] Table 5. Acrylic Film Formulations

[0107] Table 6. Characterization of Acrylic Films

[0108] As demonstrated by the data in Table 6, identical tensile properties may be achieved by using either L-MTA or DL-MTA. Furthermore, there is no difference in the glass transition temperature if L- MTA is replaced with DL-MTA in the acrylic film. As a consequence, L-MTA or DL-MTA can be used interchangeably to replace IBOA. All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

What is claimed is:

1. An acrylic film comprising a layer formed from an acrylic film composition comprising menthyl (meth)acrylate monomer.

2. The acrylic film of claim 1, wherein the acrylic film composition comprises menthyl (meth)acrylate derived from L-menthol.

3. The acrylic film of claim 1 or claim 2, wherein the menthyl (meth)acrylate is derived from biobased L-menthol.

4. The acrylic film of any one of claims 1 to 3, wherein the acrylic film composition is free of isobomyl (meth)acrylate.

5. The acrylic film of any one of claims 1 to 4, wherein the acrylic film composition comprises 0.1 to 80 wt.% menthyl (meth)acrylate monomer.

6. The acrylic film of any one of claims 1 to 5, wherein the acrylic film composition comprises a biobased content of at least 10%, preferably at least 20% of the total carbon content originating from monomers.

7. The acrylic film of any one of claims 1 to 6, wherein the acrylic film composition further comprises a monomer selected from the group consisting of a low Tg (meth)acrylate monomer, a polar (meth)acrylate monomer, and combinations thereof.

8. The acrylic film of any one of claims 1 to 7, wherein the acrylic film composition further comprises an additive selected from the group consisting of a UV absorber, a tackifier, a radical stabilizer, a corrosion inhibitor, a polymer additive, a photoinitiator, a filler, a plasticizer, a pigment, a rheological modifier, a film former, and combinations thereof.

9. The acrylic film of any one of claims 1 to 8, wherein the acrylic film is a monolithic film.

10. The acrylic film of any one of claims 1 to 9, wherein the acrylic film is a film layer of a multilayer (film) or adhesive construction.

11. The acrylic film of any one of claims 1 to 10, wherein the acrylic film further comprises other (meth)acrylate monomers in 10 to 90%, photoinitiator(s) in 0.1 to 2%, UV stabilizers in 0 to 5%, fillers in 0 to 30%, pigments in 0 to 30%, rheological additives in 0 to 10%, a film former in 0 to 15%.

12. The acrylic film of any one of claims 1 to 11, wherein the acrylic film has a thickness of 5 to 250 pm.

13. The acrylic film of any one of claims 1 to 12, wherein the acrylic film has a tensile strength of 1 to 50 MPa.

14. The acrylic film of any one of claims 1 to 13, wherein the acrylic film has an E-modulus of 1 to 2000 MPa.

15. The acrylic film of any one of claims 1 to 14, wherein the acrylic film has an elongation at break of at least 150%.

16. The acrylic film of any one of claims 1 to 15 wherein the acrylic film has an average VOC weight loss in ppm of less than 25000.

17. The acrylic film of any one of claims 1 to 16 wherein at least some of the (meth)acrylate monomers have been at least partially polymerized in an initial curing step wherein the initial monomers are free of menthyl (meth)acrylate.

18. The acrylic film of any one of claims 1 to 17 wherein at least some of the (meth)acrylate monomers have been at least partially polymerized in an initial curing step wherein the initial monomers comprise menthyl (meth)acrylate.

19. An article comprising the acrylic film of any one of claims 1 to 18.

20. The article of claim 19, wherein the article comprises an adhesive sheet or an adhesive tape.

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